PROCESS TO PRODUCE ACID ACID, METHOD FOR INHIBITING CORROSION OF A CARBONILATION REACTOR IN AN ACETI

专利摘要:
a process for producing acetic acid, a method for inhibiting corrosion of a carbonylation reactor in an acetic acid production process, and an acetic acid process or method is produced while simultaneously inhibiting an increase in hydrogen iodide concentration or production in a carbonylation reactor, or corrosion of the carbonylation reactor. ; An acetic acid production process comprises a reaction step to allow methanol to dry; continuously with carbon monoxide in the presence of a catalyst system comprising a metal catalyst (e.g. rhodium catalyst), an ionic iodide (e.g. lithium iodide), and methyl iodide in a carbonylation reactor; (i) the concentration of the metal catalyst is maintained at no less than 860 ppm, based on weight, the water concentration is maintained at 0) 8 to 15% by weight, the concentration of methyl iodide is maintained. not more than 13.9% by weight, and the concentration of 20 methyl acetat6 is maintained at not less than 0.1% by weight in an integral liquid phase in the reactor, and / or (ii) the concentration of metal catalyst is maintained at no less than 660 jppm based on weight, water concentration is maintained at 0 [8 to 3.9 wt%, ionic iodide concentration is maintained at 25 no more than 13 wt%, methyl iodide concentration is maintained at no more than 13.9% by weight, and methyl acetate is maintained at not less than 0,1% an integral liquid phase in the reactor.
公开号:BR112013014801B1
申请号:R112013014801-2
申请日:2011-12-01
公开日:2019-04-02
发明作者:Masahiko Shimizu；Ryuji Saito；Hiroyuki Miura
申请人:Daicel Corporation；
IPC主号:

专利说明:

The present invention relates to a process for producing acetic acid, while inhibiting the production (or an increase in concentration) of hydrogen iodide in a carbonyl reaction of methanol with carbon monoxide (or a carbonylation reactor by a reaction of methanol with carbon monoxide), or corrosion of the carbonylation reactor.
Prior Art
Various industrial processes for producing acetic acid are known. Among others, an industrially excellent process includes a process, which comprises continuously allowing methanol to react with carbon monoxide, using a metal catalyst (such as a rhodium catalyst), an ionic iodide (for example, lithium iodide ), and methyl iodide in the presence of water, in a carbonylation reactor, to provide acetic acid. In this process, generally, acetic acid is produced as follows: a reaction mixture of methanol and carbon monoxide, containing acetic acid, is subjected to a distillation (an instant distillation) in a vaporizer (an instant evaporator), and a component vaporized by distillation is subjected to further distillation to separate (purify) a component containing acetic acid.
The reaction mixture contains hydrogen iodide, in addition to the acetic acid product, ionic iodide, and methyl iodide. An increase in the concentration of hydrogen iodide inside the carbonylation reactor can precipitate corrosion of the carbonylation reactor. In addition, when the reaction mixture containing hydrogen iodide is subjected to a vaporizer or other distillation column to separate acetic acid, or when a residue (liquid residue or lower fraction) after separation of the vaporized component is recycled to the reactor, the reaction system may be adversely affected and, in addition, corrosion of the peripheral device (s) may be precipitated.
Therefore, in the acetic acid production process, it is preferable that the increase in concentration: of hydrogen iodide in the carbonylation reactor (or in the reaction mixture) is prevented. Although a technique for inhibiting the condensation of hydrogen iodide in a distillation column, such as plate column, fill column, is already known, a technique closely focused on hydrogen iodide in a carbonylation reactor is not known.
For example, Published Japanese Patent Application No. 2006-160645 (JP-2006-160645A, Patent Document · 1) describes a process for distilling a mixture containing hydrogen iodide and water, which comprises distilling the mixture with a water content of not more than 5% by weight, in a distillation system, to prevent condensation of hydrogen iodide in the distillation system. In the Examples in this document, a process solution (specifically, a volatile component separated by an instant distillation of a reaction mixture) free of an ionic iodide (such as lithium iodide) is examined for the effect of water concentration on condensation of hydrogen iodide. In this context, the document describes a wide range of compositions (or formulations) of the mixture (for example, the water concentration is about 0.1 to 14% by weight, the proportion of a carbonylation catalyst is about 50 at 5000 ppm, the content of the iodide salt is about 0.1 to 40% by weight, the concentration of an alkyl iodide is about 1 to 25% by weight, the concentration of a carboxylate ester is about 0.1 to 20% by weight) However, the document is silent on any relationship between the composition of these components and hydrogen iodide in the carbonylation reactor.
As described above, the goal of conventional art is to condense hydrogen iodide in distillation, and the reduction of hydrogen iodide in a carbonylation reactor has not been examined.
Summary of the Invention
Problems to be solved by the invention
It is, therefore, an object of the present invention to provide a process for producing acetic acid, while effectively inhibiting (or preventing) the increase in a concentration of hydrogen iodide in a carbonylation reactor (or in a reaction mixture), or corrosion of the carbonylation reactor.
It is another object of the present invention to provide a process for producing acetic acid, the process preventing the production of hydrogen iodide in a carbonylation reactor (or a reaction mixture), or corrosion of the carbonylation reactor, while maintaining production highly efficient of acetic acid.
It is yet another object of the present invention to provide a process for producing acetic acid, the process preventing the production of hydrogen iodide in a carbonylation reactor, or corrosion of the carbonylation reactor, while promoting energy savings.
It is yet another object of the present invention to provide a process for producing acetic acid, the process preventing corrosion of a carbonylation reactor, or subsequent process (s) or apparatus (for example, an instant evaporator and a distillation column).
Means for solving problems
The production of hydrogen iodide in a carbonylation reactor, theoretically, depends on the reaction conditions, such as a reaction temperature, a pressure, and a composition (or formulation) of each component. The inventors of the present invention have examined a method for inhibiting an increase in the concentration of hydrogen iodide in a carbonylation reaction, based on information from: such equilibrium theory. However, the temperature or pressure can be set arbitrarily, and its reaction. In addition, there are a variety of reactions involved in hydrogen iodide and these reactions are complicated.
Therefore, it was really difficult to inhibit hydrogen and the increase in hydrogen iodide concentration, while maintaining sufficiently efficient production of acetic acid, based on a simple equilibrium theory. In addition, the corrosion of the carbonylation reactor appears to be influenced, not only by the concentration of hydrogen iodide in the carbonylation reactor, but also by other conditions. Thus, a simple decrease in the concentration of hydrogen iodide has sometimes failed to efficiently inhibit the corrosion of the carbonylation reactor.
The inventors of the present invention carried out intense studies to reach the above objects and, finally, found that the production or the increase of the hydrogen iodide concentration in the reaction mixture, or in the carbonylation reactor, is inhibited, while ensuring sufficiently efficient production. of acetic acid, through the carbonylation reaction with the composition of each component rigorously controlled or selected; that inhibiting the increase in hydrogen iodide concentration prevents corrosion of the carbonylation reactor and, furthermore, reduces adverse effects (eg corrosion) caused by hydrogen iodide in step (s) or apparatus to be established after the reactor carbonylation [for example, an instant evaporator; a distillation column for subjecting a volatile component to further distillation, or its accessory installations (or apparatus) (for example, a heat exchanger, such as a circulation pump, a condenser, or a cooler); accessory installations (or apparatus) for recycling a mixture of liquid catalyst to a reactor (for example, a heat exchanger and a circulation pump); and power lines for this instant evaporator, distillation column and accessory facilities]. The present invention was carried out based on: the above conclusions.
That is, the process of the present invention includes a process for producing acetic acid, which will comprise a reaction step, to allow methanol to continuously react with carbon monoxide in the presence of a catalyst system, comprising a metal catalyst (for example, a metal catalyst). rhodium catalyst), an ionic iodide (an alkali metal iodide, such as lithium iodide), and methyl iodide in a carbonylation reactor (specifically, a reaction step to allow methanol to react with carbon monoxide to produce acetic acid ), in which, in the reaction step, (i) the concentration of the metal catalyst is maintained at not less than 860 ppm, based on weight, the water concentration is maintained from 0.8 to 15% by weight, the concentration of methyl iodide is maintained at not more than 13.9% by weight, and the concentration of methyl acetate is maintained at not less than 0.1% by weight, in an integral liquid phase in the reactor, and / or (ii ) catal concentration metal isator is maintained at not less than 660 ppm based on weight, the water concentration is maintained from 0.8 to 3.9% by weight, the ionic iodide concentration is maintained at no more than 13% by weight, the concentration of methyl iodide is maintained at not more than 13.9% by weight, and the concentration of methyl acetate is maintained at not less than 0.1% by weight; in an integral liquid phase in the reactor.
process (i) (sometimes referred to as a first process, a first embodiment, or others) and / or process (ii) (sometimes referred to as a second process, a second embodiment, or others) inhibits ( or prevents) the efficient production of hydrogen iodide in the carbonylation reactor. According to the process of the present invention, highly efficient production of acetic acid is ensured, despite inhibition of production or an increase in the concentration of hydrogen iodide. For example, in process (i), the production rate (or formation rate) of acetic acid (reaction rate, production rate of acetic acid in the reaction step) can be about no less than 10 mol / L · H (particularly, about no less than 19 mol / L · h) or, in process (ii), the acetic acid production rate can be about no less than 5 mol / L · h. In addition, process (ii) also achieves energy savings by regulating the water concentration to no more than 0.8 to 3.9% by weight.
For the first process, in the liquid phase in the reactor, the concentration of the metal catalyst can be maintained from about 860 to 5000 ppm, based on weight, the water concentration can be maintained from about 0.8 to 15% by weight , the ionic iodide concentration can be maintained at about no more than 25% by weight, and the methyl iodide concentration can be maintained from about 2 to 13.9% by weight.
For a representative example of the first process, the rate of acetic acid production can be about 10 to 45 mol / L · h (for example, about 12 to 35 mol / L · h and, preferably, about 19 at 35 mol / L h) and, in the liquid phase in the reactor, the concentration of the metal catalyst can be maintained from about 880 to 3000 ppm (for example, from about 900 to 1500 ppm) based on weight, the concentration of water can be maintained from about 1 to 10% by weight (for example, from about 1.5 to 9% by weight), the concentration of ionic iodide can be maintained from about 0.5 to 25% by weight ( for example, from about 2 to 20% by weight), the concentration of methyl iodide can be maintained from about 4 to 13.5% by weight (for example, from about 5 to 13% by weight and, preferably, from about 6 to 13% by weight), and the concentration of methyl acetate can be maintained at about not less than 0.5% by weight (for example, not less than about 1% by weight).
For the second process, in the liquid phase in the reactor, the concentration of the metal catalyst can be maintained from about 660 to 5000 ppm based on weight, the water concentration can be maintained from about 1 to 3.5% by weight, the concentration of ionic iodide can be maintained from about 0.5 to 13% by weight, and the concentration of methyl iodide can be maintained from about 2 to 13.9% by weight.
For the representative example of the second process, the acetic acid production rate can be about 5 to 45 mol / L · h (for example, about 7 to 35 mol / L · h) and, in the liquid phase in the reactor, the concentration of the metal catalyst can be maintained from about 700 to 3000 ppm, (for example, from about 800 to 1500 ppm) based on weight, the water concentration can be maintained from about 1.5 to 3 % by weight (for example, from about 2 to 2.8% by weight), the ionic iodide concentration can be maintained from about 1 to 12% by weight (for example, from about 2 to 11% by weight ), the concentration of methyl iodide can be maintained from about 3 to 12% by weight (for example, from about 4 to 11% by weight), and the concentration of methyl acetate can be maintained at about no less than 0.5% by weight (for example, not less than about 1% by weight).
In addition, according to the process of the present invention, the reaction can be carried out, while maintaining a carbon monoxide pressure (partial pressure) of not less than 900 kPa and a hydrogen pressure (partial pressure) of not less than 4 kPa in the reactor.
Indeed, it is sufficient that the process of the present invention to produce acetic acid comprises, at least, the aforementioned reaction step. Typically, the process comprises an instant distillation step for continuous supply of a vaporizer with a reactor reaction mixture to evaporate a volatile component by instant distillation, the volatile component containing at least the acetic acid product, methyl acetate, and iodide. methyl; and an acetic acid collection step to separate a stream containing acetic acid from the volatile component and collect acetic acid. According to the present invention, since the concentration of hydrogen iodide in the reaction mixture can be reduced, the production or increase in the concentration of hydrogen iodide can be inhibited (or prevented) in these steps to be established after the reaction. For example, in the instant distillation step, the reaction mixture can be separated into the volatile component and a mixture of liquid catalyst (background fraction) containing at least the metal catalyst and ionic iodide, and the concentration of hydrogen iodide. can be kept no more than; 1% by weight, based on the weight of the liquid catalyst mixture.
For the process comprising such an instant distillation step, in the instant distillation step, the volatile component can be separated from the reaction mixture, and the instant distillation can be carried out, provided that the concentration of methyl acetate is not less than 0.6¾ in the liquid catalyst mixture containing at least the metal catalyst and the ionic iodide. Instant distillation under such a condition furthermore advantageously inhibits the increase of the hydrogen iodide concentration in the instant evaporator.
The concentration of methyl acetate in the liquid catalyst mixture can be not less than 1.5% by weight (in particular, not less than 2% by weight). In addition, the water concentration in the liquid catalyst mixture can be not more than 15% by weight, the concentration of the metal catalyst in the liquid catalyst mixture can be not less than 300 ppm, based on weight. In addition, in the liquid catalyst mixture, the concentration of acetic acid can be not less than 40% by weight.
Representatively, with regard to the concentration of each component in the liquid catalyst mixture, the ionic iodide concentration may not be greater than 50% by weight, the concentration of methyl iodide may not be greater than 5% by weight, the concentration of acetic acid can be about 45 to 90% by weight, and the water concentration can be no more than 10% by weight. In particular, with regard to the concentration of each component in the liquid catalyst mixture, the concentration of ionic iodide can be not more than 40% by weight, the concentration of methyl iodide can be about 0.01 to 4% by weight, the concentration of acetic acid can be about 50 to 85% by weight, the concentration of methyl acetate can be about 0.7 to 5% by weight, and the concentration of water can be about from 0.8 to 8% by weight.
In the instant distillation step, instant distillation can be carried out at an absolute pressure of 0.1 to 0.5 MPa, and the temperature (or instant distillation temperature) in the liquid catalyst mixture can be about 100 to 170 °. Ç.
In the process of the present invention, the concentration of each component in the flash evaporator can be adjusted by adding each component or component (s) to produce each component. For example, the concentration of methyl acetate in the liquid catalyst mixture can be adjusted (for example, adjusted to not less than 0.6% by weight), by adding or mixing methyl acetate and / or a production component of methyl acetate to the reaction mixture and / or to the instant evaporator.
According to the present invention, as described above, strict control of each component concentration in the carbonylation reactor can prevent (or inhibit) the production or increase of the hydrogen iodide concentration in the carbonylation reactor (moreover, ai ( s) next step (s), such as the instant distillation step) and then can efficiently prevent (or inhibit) corrosion of the carbonylation reactor, or step (s) or apparatus ( s) to be established after the carbonylation reactor.
Thus, the present invention also includes a method for inhibiting the corrosion of a carbonylation reactor in an acetic acid production process, the production process comprising a reaction step to allow methanol to continuously react with carbon monoxide in the presence of a catalyst system comprising a metal catalyst, an ionic iodide, and methyl iodide in the carbonylation reactor, characterized in that, in the reaction step, (i) the concentration of the metal catalyst is maintained at not less than 8 60 ppm, based by weight, the concentration of water is maintained from 0.8 to 15% by weight, the concentration of methyl iodide is maintained at not more than 13.9% by weight, and the concentration of methyl acetate is maintained at not less 0.1% by weight, in an integral liquid phase in the reactor, and / or (ii) the concentration of the metal catalyst is maintained at not less than 660 ppm, based on weight, the concentration of water is maintained at 0.8 3.9% in feet o, the concentration of ionic iodide be maintained at not more than 13% by weight, the concentration of methyl iodide be maintained at not more than 13.9% by weight, and the concentration of methyl acetate be maintained at not less than 0.1% by weight, in an integral liquid phase in the reactor.
Such a method not only prevents production or increase; the concentration of hydrogen iodide, or the corrosion of the carbonylation reactor, but it also achieves a highly efficient production of acetic acid. For example, ; in process (i), the production rate of acetic acid can be about no less than 10 mol / L · h, and in process (ü), the production rate of acetic acid can be about no less than 5 mol / L · h.
In the process or method of the present invention, the carbonylation reactor material (in addition, the vaporizer) can comprise an alloy (e.g., a nickel-based alloy). The present invention achieves corrosion inhibition, and even a carbonylation reactor made of such a relatively corrosive material can preferably be used.
Throughout the description, the total proportion (s) of any / any component (s) existing in the same mixing system (such as the liquid phase in the carbonylation reactor, or the liquid catalyst mixture) does not is more than 100% by weight; and the proportions of all components are 100% by weight in total.
Effects of the Invention
According to the process of the present invention, acetic acid can be produced efficiently, while inhibiting (or preventing) the increase in the concentration of hydrogen iodide in the carbonylation reactor (or in the reaction mixture), or the corrosion of the reactor carbonylation. In particular, according to the process, the production of acetic acid does not decrease, and the production of hydrogen iodide in the carbonylation reactor or the corrosion of the carbonylation reactor can be avoided, while maintaining highly efficient production. In addition, according to the process of the present invention, the production of hydrogen iodide in the carbonylation reactor, or corrosion of the carbonylation reactor, can be avoided, while promoting energy savings. In addition, according to the process of the present invention, as described above, in connection with preventing the production of hydrogen iodide, corrosion of the carbonylation reactor or subsequent process (es) or apparatus (s) (for example, an instant evaporator, and a distillation column) can be prevented. Therefore, acetic acid can be efficiently produced without forming the carbonylation reactor or subsequent process (es) or apparatus (s) with a high quality material having a high resistance to corrosion. Thus, the present invention allows the use of a cheap or low quality material, so that the cost of the acetic acid production process can be reduced efficiently.
Brief Description of Drawings
Fig. 1 is a diagram for explaining a production process (or production apparatus) for acetic acid, according to an embodiment of the present invention.
Description of Forms of Realization
Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a diagram (a flowchart, a schematic process drawing, or a plan layout drawing) for explaining a production process (or production apparatus) for acetic acid, according to an embodiment of the present invention.
The embodiment of Fig. 1 shows a continuous process (or apparatus) for producing acetic acid (CH3COOH), from a liquid reaction medium (or reaction mixture), generated by a continuous methanol carbonyl reaction (MeOH ) presence of a carbon monoxide (CO) system in the catalyst, comprising; a rhodium catalyst as a metal catalyst and a cocatalyst [lithium iodide as an ionic iodide (or iodide salt) and methyl iodide], as well as acetic acid, methyl acetate, and a finite amount of water.
The process (or production apparatus) comprises; a reactor (reaction system) 1 to carry out the reaction: methanol carbonylation mentioned above; a vaporizer i or evaporator (instant evaporator) 2 to separate i a volatile component or a stream of acetic acid (a fraction with a lower boiling point) containing at least the product acetic acid, methyl acetate, and methyl iodide, and a mixture of liquid catalyst (a low volatility component or a higher boiling fraction) containing essentially a catalyst component (a higher boiling component) (eg a rhodium and lithium iodide catalyst) from a liquid reaction medium (or a reaction mixture, or a reaction solution), which is introduced from reactor 1, through a feed line 14, and contains acetic acid generated by the reaction; a first distillation column (dividing column) 3 to separate or extract at least part of a lower boiling fraction containing a lower boiling component (eg, methyl iodide, methyl acetate, and acetaldehyde) out of the volatile component introduced from vaporizer 2, through a supply line 15, as a supernatant from the top of its column, and extract a stream containing acetic acid (a stream of acetic acid) in the form of a side stream by side cut; a second distillation column 4 to extract at least part of a lower boiling fraction containing a lower boiling component as a supernatant from an upper part of its column, out of the acetic acid stream introduced from the first distillation column 3, through a feed line 23, by lateral cut, separate at least part of a component with a higher boiling point (impurities with a higher boiling point) (containing, for example, water and propionic acid),
from a bottom part of column, and get an current Acetic Acid through of a line in food 29, as a chain side per cut side.Beyond addition, this process is endowed with one
condenser or a heat exchanger to condense a component introduced through each line. Specifically, the reactor 1 is equipped with a condenser 5 to condense a condensable component in a flue gas (vapor) discharged through a discharge line 11; a recycling line 12 for recycling a liquid component condensed by the condenser 5 to the reactor 1; and a discharge line 13 for discharging a gaseous component, which is a non-condensing component in the condenser 5.
In addition, in this process, the vaporizer 2 is equipped with a heat exchanger 6 to cool a liquid catalyst mixture (or lower fraction) separated by the vaporizer 2 and discharged from the bottom of the vaporizer 2, through a discharge line 18; a recycling line 19 for recycling the liquid catalyst mixture cooled by the heat exchanger 6 to reactor 1; a heat exchanger 7 for condensing a condensable component in part of the volatile component (or volatile phase) discharged as a supernatant from the vaporizer 2 and introduced through a supply line 15a; a discharge line 16 for discharging a gaseous component, which is a non-condensable component in the heat exchanger 7; and a line _; recycling method 17 to recycle a liquid component (or liquefied) containing acetic acid condensed by heat exchanger 7 to reactor 1.
In addition, in the present process, the first distillation column 3 is equipped with a condenser 8 to condense a condensable component in the fraction with the lowest boiling point, or supernatant discharged through a discharge line 20; a recirculation line 22 for recycling a liquid component condensed by the condenser 8 to the reactor 1; a recycling line 22a for recycling (or refluxing) part of the liquid component condensed by the condenser 8 to the first distillation column 3; a discharge line 21 for discharging a gaseous component, which is a non-condensable component in the condenser 8; and a line 24 for discharging a fraction with the highest boiling point í into the first distillation column 3 and recycling the fraction with the highest boiling point into reactor 1. In this context, the liquid component recycled to the first column: distillation 3 is used to reflux the first distillation column 3.
In addition, in this process, the second distillation column 4 is equipped with a condenser 9 to condense a condensable component in the fraction with the lowest boiling point, or supernatant discharged through a discharge line 25; a recycling line 27 to recycle (or reflux into) a liquid component or lower 'boiling point condensed by the condenser 9 to the second distillation column 4, a discharge line (recycling line) 26 to separate a part or all of the liquid component or fraction with a lower boiling point condensed by condenser 9, starting from line 27, and recycling the fraction or separate component to reactor 1; and a line 28 for feeding a separate gas in the condenser to a washer 10 through a line 13.
This process shown in FIG. 1 further comprises a purifying or washing system 10 for recovering gaseous components (or non-condensing components) or others discharged by condenser 5, the heat exchanger
heat 7, and capacitor 8, and abandon the components and / or recycle the components for the system in reaction (per example, O reactor 1). In this context, an line for recycle O gaseous component, or others, of system of
wash 10 for the reaction system (for example, reactor 1) is omitted in FIG. 1.
Hereinafter, the process shown in FIG. 1 will be explained in more detail.
Methanol as a liquid component and carbon monoxide as a gaseous reagent can be continuously fed to reactor 1 at a predetermined rate, and a catalyst mixture (a liquid catalyst mixture) containing a carbonylation catalyst system [a catalyst system comprising a main catalyst component (for example, a rhodium catalyst) and a co-catalyst (for example, lithium iodide and methyl iodide)] and water can be continuously fed to reactor 1. In addition, fraction (s) ( for example, in the form of a liquid) containing the lowest boiling point fraction (s) and / or the highest boiling point fraction (s), starting from the next step (s) (for example, example, the vaporizer 2, the first and second distillation columns 3 and 4, the heat exchanger 7, and the washing system 10) can also be fed to the reactor 1.
The internal pressure of reactor 1 (for example, the reaction pressure, partial pressure of carbon monoxide, partial pressure of hydrogen, partial pressure of methane, and partial pressure of nitrogen) can be maintained by extracting steam from the top of the column and introducing the extracted steam into condenser 5. The extracted steam is cooled by condenser 5, to provide a liquid component (containing acetic acid, methyl acetate, methyl iodide, acetaldehyde, water, and others) and a gaseous component (containing monoxide carbon, hydrogen, and others). The resulting liquid component is recycled to reactor 1, and the resulting gaseous component (waste gases) is discharged to the washing system 10 and, if necessary, recycled to reactor 1. In particular, the reaction system is a exothermic reaction, which accompanies the generation of heat, and part of the amount of heat generated in the reactor can be removed by cooling part of the reaction heat transferred from the steam reaction solution with the condenser 5.
Since the reaction system is an exothermic reaction system, which accompanies heat generation, the reactor 1 can be equipped with a heat removal (or heat extraction) or cooling unit (for example, a jacket), to control a reaction temperature. In this context, as described later, the process of Fig. 1 is equipped with a heat exchanger 7, to extract heat from part of a volatile component of the instantaneous evaporator 2. Thus, even when the reactor is not equipped with the removal unit heat or cooling, heat can be removed.
Components contained in the reaction mixture (crude reaction solution) generated in reactor 1 may include acetic acid, hydrogen iodide, a component with a lower boiling point or impurity with a lower boiling point having a lower boiling point than that of acetic acid (for example, methyl iodide as a co-catalyst, methyl acetate as a reaction product of acetic acid with methanol and acetaldehyde, crotonaldehyde, 2-ethylcrotonaldehyde, and a higher iodide (such as hexyl iodide or decyl iodide) , in the form of by-products), and a component with a higher boiling point or impurity with a higher boiling point having a higher boiling point than that of acetic acid [a metal catalyst component (a rhodium catalyst, and lithium iodide as a co-catalyst), propionic acid, and water]. In the embodiment of Fig. 1, the concentration of each component in at least one composition (liquid phase) in reactor 1 is strictly adjusted, as described later, and the production (or increase in concentration) of hydrogen iodide in the reactor (or reaction mixture) is significantly inhibited.
In order to essentially separate the highest boiling point component (such as the metal catalyst component) from the reaction mixture, the reaction mixture; (or part of the reaction mixture) is continuously extracted from reactor 1 and introduced or fed to the vaporizer (instant evaporator) 2. In vaporizer 2, a volatile component or a fraction of a lower boiling point (containing essentially acetic acid, which is a product and also works as a reaction solvent, methyl acetate, methyl iodide , water, hydrogen iodide, and others) is evaporated by instant distillation, to separate a mixture of liquid catalyst or a higher boiling fraction (essentially containing a metal catalyst component, for example, a rhodium catalyst, iodide lithium, and others) of the reaction mixture. In this context, in the liquid catalyst mixture, the metal catalyst component and, in addition, the remaining components without evaporation (for example, acetic acid, methyl iodide, water, and methyl acetate) are also contained.
Within vaporizer 2, instant distillation is carried out, so that at least methyl acetate in the liquid catalyst mixture can be maintained at a predetermined concentration (for example, not less than 0.1% by weight, in particular, not less than 0,6% by weight).
Such conditions and the adjustment of the composition in the reactor are combined to avoid increasing the concentration of hydrogen iodide in the instant evaporator. Thus, corrosion of the evaporator can be markedly prevented. In this context, the concentration of methyl acetate can be adjusted by increasing the concentration of methanol in the
mix of reaction, and allows the reaction in methanol with Acetic Acid occur predominantly, and others. If required, The concentration of acetate in methyl at the evaporator snapshot also Can be adjusted per mixing in acetate of methyl and / or a component in
production of methyl acetate (for example, methanol and dimethyl ether), through a line 30, which joins line 14, with the reaction mixture of reactor 1.
The liquid catalyst mixture is continuously discharged from the bottom of the column. The discharged liquid catalyst mixture can be directly recycled to reactor 1. In the embodiment shown in the figure, the discharged liquid catalyst mixture has its heat removed (it is cooled) in heat exchanger 6 and then recycled to the reactor 1.
On the other hand, the volatile component, or fraction with the lowest boiling point (acetic acid stream), is extracted from the top of the column or top of the vaporizer 2 and fed or introduced into the first distillation column 3, and part of the component volatile is introduced into the heat exchanger 7, to be condensed. The volatile component cooled by the heat exchanger 7 produces a liquid component (containing acetic acid, methanol, methyl iodide, methyl acetate, water, propionic acid, acetaldehyde, and others) and a gaseous component (containing carbon monoxide, hydrogen, and others). The resulting liquid component is recycled to reactor 1. The resulting gaseous component (waste gases) is fed to the washing system 10 and, if necessary, carbon monoxide is obtained without purifying the gaseous component, or with its purification by the method of PSA (Pressure Swing Adsorption), and recycled to reactor 1. The lowest boiling point fraction is extracted from the vaporizer for introduction into the heat exchanger, and part of the reaction heat transferred from the instant steam reaction solution is cooled by the exchanger. of heat. Thus, the heat can be removed efficiently. Thus, since the subsequent distillation column or condenser can be reduced (or miniaturized), even for a large plant, acetic acid can be produced with high purity and high performance in a resource and energy saving equipment. In addition, heat can be removed without installing a refrigeration unit with external circulation in the reactor, which leads to preventing the loss of carbon monoxide and improving the reaction efficiency, or reducing the cost of the equipment.
In the first distillation column 3, usually the fraction with the lowest boiling point (or supernatant) containing the component with the lowest boiling point (containing methyl iodide, methyl acetate, acetaldehyde, water, etc.) is separated by the top or upper part of the column and fed to condenser 8, and a fraction of the highest boiling point containing the component with the highest boiling point (for example, propionic acid, a entrained catalyst, and lithium iodide), is separated by the bottom or bottom of the column, through a bottom line 24, and recycled to reactor 1. The fraction with the highest boiling point (first fraction with the highest boiling point) contains the component with the highest boiling point, as well as the lowest boiling point, which remains, without evaporation, acetic acid, and others. Part of the fraction with the highest boiling point discharged through line 24 can be recycled to vaporizer 2, via line 24a, if necessary. A side stream (acetic acid stream or crude acetic acid stream) containing essentially acetic acid is extracted from the first distillation column 3 by side cutting and is fed or introduced into the second distillation column 4.
The fraction with the lowest boiling point (supernatant, or first supernatant, or the first fraction with the lowest boiling point) extracted from the top or top of the first distillation column 3 contains acetic acid and others, and is fed to the condenser 8. The fraction with the lowest boiling point extracted from the first to cool the reaction solution through the instantaneous vapor with the condenser 8 and thus part of the reaction heat can be removed. In the condenser
8, the lowest boiling point fraction is condensed to separate a gaseous component containing essentially carbon monoxide, hydrogen and others, and a liquid component containing methyl iodide, methyl acetate, acetic acid, acetaldehyde and others. The gaseous component separated from the condenser 8 is fed to the L0 washing system, if necessary, carbon monoxide is obtained without purifying the gaseous component, or with its purification by the PSA (Pressure Swing Adsorption) method, and recycled to the system reaction (for example, reactor 1) (not shown). The liquid component separated in the capacitor 8 can; be recycled to the first distillation column 3, through line 22a. In this context, the liquid component can either be a uniform solution or a separate solution (for example, a biphasic solution). For example, for the liquid component containing a predetermined amount of water, the liquid component can be separated into two compound phases
water) and an oil phase (organic phase or organic layer), where the aqueous phase contains acetic acid, acetaldehyde, and others, and the oil phase contains methyl iodide and others. In addition, the oil phase can be recycled to reactor 1 and / or the first distillation column 3, and the water phase (water phase) can be recycled to reactor 1 and / or the first distillation column 3.
In the acetic acid stream, which is obtained by cutting
for distillation second column one 4, component is fed
lowest boiling point (eg water),
remains
chain

acetic,
further separated in the second distillation column 4, and a stream of higher purity acetic acid (purified stream of jacetic acid) is extracted as a side stream. In the second distillation icon 4, a fraction with the lowest boiling point (supernatant, or second supernatant, or the second fraction with the lowest boiling point) containing the component with the lowest boiling point; it is fed from the top or top of the column to condenser 9, and a side chain (acetic acid stream), rich in acetic acid, is distilled by lateral cut. If necessary, the lowest boiling point fraction discharged from the top or top of the column can be recycled to the second distillation column 4 and / or reaction system 1. Water can be separated as a component of
4, or it can be separated, essentially, in
3, and further separated on the second distillation column 4 for purification. In this context, a higher boiling point (one with a higher boiling point), as a component with a higher propionic point) can be discharged from the bottom or bottom of the column and, if necessary, can be recycled to reactor 1, or can be downloaded from the system (not shown).
The fraction with the lowest boiling point extracted by the top or top of the second distillation column 4 contains methyl iodide, methyl acetate, water, acetaldehyde and others, and is condensed by condenser 9. Then the fraction of the lowest point boiling condensate in condenser 9 can be recycled to reactor 1, via line 26, or recycled to the second distillation column 4, via line 27. In addition, to the liquid component containing a predetermined amount of water, of the same As in the first distillation column, the liquid component can be separated into an aqueous phase and an oil phase, and these phases can be recycled. The fraction with the lowest boiling point extracted from the second distillation column 4 is condensed by the condenser 9, to cool part of the heat transferred from the reaction solution to the fraction with the lowest boiling point, through the instantaneous vapor with the condenser 9.
[Reaction step]
In the reaction stage (carbonylation reaction stage), methanol is carbonylated with carbon monoxide in the presence of the catalyst system. In this context, fresh methanol can be fed to the reaction system directly or indirectly, or methanol and / or its derivative removed by several distillation steps can be recycled and fed to the reaction system.
Inside the carbonylation reactor, a system
reaction in phase liquid containing the reagent and O component in bigger point of boiling [for example, O component catalyst metal (e.g., one
rhodium catalyst), and ionic iodide (eg, lithium iodide)] is in equilibrium with a vapor phase system containing carbon monoxide, by-products by reaction (hydrogen, methane, carbon dioxide), and a component of lower vaporized boiling point (eg methyl iodide, acetic acid as a product, and methyl acetate), and a methanol carbonylation reaction occurs under agitation by a stirrer or other means.
The catalyst system can normally comprise a metal catalyst, a co-catalyst and an accelerator. Examples of the metal catalyst may include a transition metal catalyst, in particular a metal catalyst containing group 8 metal from the Periodic Table (e.g., a cobalt catalyst, a rhodium catalyst, and an iridium catalyst). The catalyst can be a metal, as a simple substance, or it can be used in the form of an oxide (including a complex metal oxide), a hydroxide, a halide (for example, a chloride, a bromide, and an iodide) , a carboxylate (for example, an acetate), a salt of an inorganic acid (for example, a sulfate, a nitrate, and a phosphate), a complex, and others. These metal catalysts can be used alone or in combination. The preferred metal catalyst includes a rhodium catalyst and an iridium catalyst (in particular, a rhodium catalyst).
In addition, it is preferable to use the metal catalyst in the form dissolved in a reaction solution. In this context, since rhodium generally exists as a complex in the reaction solution, the shape of the rhodium catalyst is not particularly limited to a specific type, since the catalyst can change to a complex in the reaction solution, and can be used in various ways. As such, a rhodium catalyst, a rhodium iodide complex [eg, RHI ₃ , [RHI ₂ (C0) ₄ ] ', and [Rh (CO) ₂ I2], w rhodium carbonyl complex, or the like, it is particularly preferred. In addition, the catalyst can be stabilized in the reaction solution by adding an ionic iodide (for example, an iodide salt) and / or water.
As the co-catalyst or accelerator contained in the catalyst system, an ionic iodide (an iodide salt) is used. The iodide salt is added in order to stabilize the rhodium catalyst and inhibit side reactions, in particular, in a low water content. The iodide salt; de is not particularly limited to a specific type, as the iodide salt produces an iodide ion in the reaction solution. The iodide salt can include, for example, a metal halide (e.g., a metal iodide, such as an alkali metal iodide (e.g., lithium iodide, sodium iodide, potassium iodide, rubidium iodide, cesium iodide), an alkaline earth metal iodide (for example, beryllium iodide, magnesium iodide, and calcium iodide), or a group 3B metal iodide in the Periodic Table (for example, boron iodide and aluminum iodide )], an organic halide [for example, an organic iodide, such as a salt of iodide: phosphonium (phosphonium iodide) (for example, a salt with triphenylphosphine and tributylphosphine), or an ammonium salt of an iodide (iodide ammonium) (for example, a tertiary amine salt, a pyridine compound, a compound; imidazole, an imide compound, or the like, with) an iodide), a bromide corresponding to the iodide, and a chloride corresponding to the iodide ]. In this context, alkali metal iodide (for example, lithium iodide) also functions as a stabilizer for the carbonylation catalyst (for example, a rhodium catalyst). These iodide salts can be used alone or in combination. Among these iodide salts, an alkali metal iodide (such as lithium iodide) is preferred.
For accelerator contained in the catalyst system, an alkyl iodide (e.g. a Cl - ₄ alkyl iodide such as methyl iodide, ethyl iodide or propyl iodide), in particular methyl iodide, is used . Thus, the accelerator may contain at least methyl iodide.
In the carbonylation reaction, acetic acid is produced, and the esterification of the acetic acid product with methanol is accompanied by the generation of methyl acetate, water and others. Acetic acid can also be used as a reaction solvent. In addition, since the reaction is a consecutive reaction, such a component always exists in the carbonylation reactor. In addition, such a component also exists as a recycled component from the following steps.
Thus, inside the carbonylation reactor there are several components, such as the components produced and the recycled components, in addition to the catalyst components. According to the current production of hydrogen iodide, regulation) of the concentrations of these components. From now on, for each of the first and second processes, the concentration of each component will be explained in detail separately.
(First process)
It is sufficient that the concentration of the metal catalyst (for example, the concentration of the rhodium catalyst) in the entire liquid phase in the reactor is not less than 860 ppm (for example, from 860 to 5000 ppm) based on weight. For example, the concentration of the metal catalyst can be from about 870 to 4000 ppm, preferably from about 880 to 3000 ppm and, more preferably, from about 90 0 to 1/5 00 ppm.
In addition, it is sufficient that the water concentration in the entire liquid phase in the reactor is not less than 0.8% by weight (for example, from 0.8 to 20% by weight). For example, the water concentration can be about 0.8 to 15% in
weight preferably of fence from 1 to 10% by weight (per example, of fence 1.5 to 9% in Weight), more preferably, about 1.7 to 8% by weight (per example, about 1.8 at 7% in weight), and usually, in
about 1 to 6% by weight (for example, about 1.5 to 5% by weight).
In addition, it is sufficient that the concentration of methyl iodide in the entire liquid phase in the reactor does not exceed 13.9% by weight (for example, from 1 to 13.9% by weight). For example, the concentration of methyl iodide can be from about 2 to 13.9% by weight (for example, from about 3 to 13.5% by weight), preferably from about 4 to 13% by weight weight (for example, from about 5 to 12% by weight), more preferably, from about 6 to 11% by weight, and usually from about 4 to 13.5% by weight (for example, from about 6 to 13% by weight).
Incidentally, the concentration of ionic iodide (eg, lithium iodide) is not particularly limited to a specific value. For example, the concentration of ionic iodide in the entire liquid phase in the reactor can be no more than 30% by weight (for example, from about 0.3 to 30% by weight), preferably not more than 25% by weight. weight (for example, from about 0.5 to 25% by weight) and, more preferably, not more than 20% by weight (for example, from about 2 to 20% by weight).
In addition, the concentration of methyl acetate by hand is particularly limited to a specific value, and the concentration of methyl acetate in the entire liquid phase in the reactor can be selected from the range of not less than 0.1% by weight ( for example, from 0.2 to 25% by weight). For example, the concentration of methyl acetate can be not less than 0.3% by weight (for example, from about 0.4 to 20% by weight), preferably less than 0.5% by weight ( for example, from about 0.6 to 18% by weight), more preferably, not less than 1% by weight (for example, from about 1.2 to 15% by weight) and, in particular, not less than 1.5% by weight (for example, from about 1.8 to 10% by weight).
By the way, the concentration of acetic acid in the entire liquid phase in the reactor can be, for example, not less than 30% by weight (for example, from about 30 to 90% by weight), preferably not less than 35 % by weight, (for example, from about 35 to 85% by weight) and, more preferably, not less than 40% by weight (for example, from about 45 to 80% by weight).
The reaction under such conditions allows reduced reactor corrosion and improved acetic acid production.
(Second process)
It is sufficient that the concentration of the metal catalyst (for example, the concentration of the rhodium catalyst) in the entire liquid phase in the reactor is not less than 660 ppm (for example, from 660 to 5000 ppm) based on weight. For example, the concentration of the metal catalyst can be from about 700 to 3000 ppm, preferably from about 750 to 2,000 ppm and, more preferably, from about 800 to 1500 ppm.
In fact, it is sufficient that the water concentration in the entire liquid phase in the reactor is from 0.8 to 3.9% by weight. For example, the water concentration can be from about 1 to 3.5% by weight (for example, from about 1.2 to 3.3% by weight), preferably from about 1.5 to 3 % by weight (per
example of fence from 1.7 to 2.9% by weight) and, more in preferably, about 1.8 to 2.8% by weight. Beyond of this, it is enough that the concentration of ionic iodide (for example, lithium iodide) be no superior than 13% in Weight. Per example, concentration of ionic iodide can be about 0.5 to 13% in Weight, in preferably, of about 1 to 12% by weight and more
preferably, from about 2 to 11% by weight.
In addition, it is sufficient that the concentration of methyl iodide in the entire liquid phase in the reactor is not more than 13.9% by weight (for example, from 1 to 13.9% by weight). For example, the concentration of methyl iodide can be from about 2 to 13.5% by weight (for example, from about 3 to 13.5% by weight), preferably from about 4 to 13% by weight weight (for example, from about 5 to 12% by weight), more preferably, from about 6 to 11% by weight and, usually, from about 2 to 13.9% by weight.
In addition, the concentration of methyl acetate is no longer particularly limited to a specific value, and the concentration of methyl acetate in the entire liquid phase in the reactor can be selected from the range of not less than 0.1% by weight ( for example, from 0.3 to 25% by weight). For example, the concentration of methyl acetate can be not less than 0.3% by weight (for example, from about 0.4 to 20% by weight), preferably not less than 0.5% by weight ( for example, from about 0.6 to; 18% by weight), more preferably, not less than 1% by weight (for example, from about 1.2 to 15% by weight) and, in particular, not less to 1.5% by weight (for example, from about 1.8 to 10% by weight).
By the way, the concentration of acetic acid in the entire liquid phase in the reactor can be, for example, less than 30% by weight (for example, from about 30 to 90% by weight), preferably not less than 35% by weight (for example, from about 35 to 85% by weight) and, more preferably, not less than 40% by weight (for example, from about 45 to 80% by weight).
The reaction under such conditions allows reduced reactor corrosion and improved acetic acid production.
In the first and second processes, the concentration of each component can be regulated, through an appropriate adjustment of the quantity of each component to be fed to the reaction system, or the quantity of each component to be recycled to the reaction system, the temperature reaction, reaction pressure, and others; additional energy savings can be made.
carbon monoxide to be fed to the reaction system can be used as a pure gas, or it can be used as a gas diluted with an inactive gas (eg nitrogen, helium and carbon dioxide). In addition, discharged gas component (s) containing carbon monoxide obtained from the next step (s) can be recycled to the reaction system. In addition, in the carbonylation reaction, hydrogen is formed (or generated) by a displacement reaction between carbon monoxide and water. In order to increase the activity of the catalyst, if necessary, hydrogen can be fed into the reaction system. Hydrogen can be fed as a gas mixture of carbon monoxide as a raw material for the reaction system. In addition, hydrogen can be fed to the reaction system by recycling gaseous component (s) (including hydrogen,
carbon, and others) discharged i in step (s) in distillation following (s) (column distillation), if required, after in debug properly o (s)
gaseous component (s).
The pressure of carbon monoxide (partial pressure) in the reactor can be, for example, not less than 300 kPa (for example, from about 500 to 5000 kPa), preferably not less than 600 kPa (for example, of about 800 to 4000 kPa) and, more preferably, not less than 900 kPa (for example, from about 1000 to 3000 kPa).
In addition, the partial pressure of hydrogen in the reactor can be, for example, not less than 1 kPa (for example, from about 2 to 200 kPa), preferably not less than 2 kPa (for example, about 3 at 150 kPa) and, more preferably, not less than 4 kPa (for example, from about 5 to 100 kPa). When carrying out the reaction, while maintaining such partial pressure of carbon monoxide 'or hydrogen, the production of hydrogen iodide can be inhibited, while more efficiently ensuring the production of acetic acid.
The partial pressure of carbon monoxide or the partial pressure of hydrogen in the reaction system can be adjusted, for example, through an appropriate adjustment of the amount of carbon monoxide and hydrogen fed and / or recycled to the reaction system, the amount raw materials (eg methanol) fed to the reaction system, temperature: from
In the case of may be, for example, about 150
250: ° C, preferably about
160 to 230 ° C and, more preferably, from about 180 to 220 ° C.
In addition, that of the reactor) can be, for example, from about 15 to 40 atmospheres.
aldehydes can be reduced or inhibited by extracting the aldehyde in the reaction stream, for example, by reducing the proportion of the catalyst, such as an alkyl iodide, and / or the partial pressure of hydrogen. In addition, hydrogen generation in the reaction system can be reduced or inhibited by adjusting the water concentration and / or the methyl acetate concentration.
The present invention achieves not only an inhibited production of hydrogen iodide, but also the highly efficient production of acetic acid.
For example, in the first process, the rate of (reaction rate, space / time yield) of acetic acid can be selected from the interval h (hour) (for example, from 10 to 45 mol / L. · H) , and can be, for example, not less than 12 mol / L · h (for example, from about 12 to 35 mol / L · h) and, in particular, not less than 19 mol / L · h (for example , from about 19 to 35 mol / L · h, preferably from about 20 to 33 mol / L · h, more preferably, from about 22 to 30 mol / L · h).
In the second process, the acetic acid production rate can be selected from the range not less than 5 mol / L · h (for example, from 5 to 4.5 mol / L · h), and can be, for example, not less than 7 mol / L · h (for example, about 7 to 35 mol / L · h) and preferably not less than 9 mol / L · h (for example, about 10 to 30 mol / L) · H).
The concentration of hydrogen iodide in the entire liquid phase in the reactor (or the reaction mixture) can, for example, be regulated (or adjusted) to no more than 1% by weight (for example, from about 0 or the limit of detection at 0.8% by weight), preferably not more than 0.6% by weight (for example, from about 0.001 to 0.5% by weight), more preferably, not more than 0.3% by weight weight (for example, from about 0.01 to 0.2% by weight) and usually not more than 0.1% by weight (for example, from about 0 or 0.09% detection limit in weight preferably about 0 or 0.07 wt% detection limit and most preferably about 0.05 wt% detection limit).
The hydrogen iodide concentration can be measured directly, or measured (or calculated) indirectly. For example, the concentration of the iodide ion derived from the iodide salt [for example, an iodide derived from the cocatalyst, such as Lil, and a metal iodide (for example, a corroded metal iodide (such as Fe, Ni , Cr, Mo or Zn), produced in the acetic acid production process)], can be subtracted from the total concentration of iodide ions (I), to determine (or calculate) the concentration of hydrogen iodide.
The vapor component extracted from the top of the reactor, for the purposes of reactor pressure control, or others, is preferably cooled with a condenser, a heat exchanger, or other means to remove part of the reaction heat. It is preferable that the cooled vapor component is separated into a liquid component (containing acetic acid, methyl acetate, methyl iodide, acetaldehyde, water, and others) and a gaseous component (containing carbon monoxide, hydrogen, and others) o liquid component is recycled to the reactor, and the gaseous component is introduced into the washing system.
The material of (or to form) the carbonylation reactor is not particularly limited to a specific type, and can be a metal, ceramic, glass, or the like. In a practical way, a carbonylation reactor made of a metal is used. In particular, according to the present invention, in connection with the significant impediment of elevation of the hydrogen iodide concentration inside the reactor, and others, corrosion of the carbonylation reactor can be inhibited. Thus, for a carbonylation reactor (reaction vessel) in the present invention, it can be used, not only in a reactor made of an expensive material having a high resistance to corrosion (such as zirconium), but also a reactor made of a relatively cheap material having a not high resistance to corrosion, for example, a metal as a simple substance (for example, titanium or aluminum) and an alloy [for example, a transition metal-based alloy, such as an iron-based alloy ( or an iron-containing alloy as a major component, for example, a stainless steel (including a stainless steel containing chromium, nickel, molybdenum and others), a nickel-based alloy (or a nickel-containing alloy as a major component, for example , HASTELLOY (trade name) and INCONEL (trade name)), a cobalt based alloy (or a cobalt containing alloy as the main component), or a titanium alloy; and an aluminum alloy].
The reaction system (or the reaction mixture) also contains methanol (unreacted methanol). Such methanol can be adjusted, in association with the concentration of methyl acetate, as described later. Ά methanol concentration in the reaction system can be, for example, not more than 1% by weight (for example, from about 0 to 0.8% by weight), preferably not more than 0.5% by weight (for example, from about 0 to 0.3% by weight), more preferably, not more than 0.3% by weight (for example, from about 0 to 0.2% by weight) and usually not above the detection limit (eg 0.1% by weight).
[Instant distillation step or catalyst separation step]
In the instant distillation step (vaporizer), from the reaction mixture fed by the reaction step or the reactor to the vaporizer (instant evaporator or instant distillation column), a low volatility component or liquid catalyst mixture (a fraction of higher boiling point) containing at least one higher boiling point catalyst component (a metal catalyst component, for example, a rhodium catalyst and an ionic iodide salt) is separated as a liquid (component) , and a volatile component or volatile phase (a fraction of a lower boiling point) containing acetic acid is separated as a vapor (component).
In the instant distillation step (instant evaporation step), the reaction mixture can be separated into the vapor component (or vaporized stream) and the liquid component (or liquid stream) with or; without heating. For example, in adiabatic vaporization, the reaction mixture can be separated into the vapor component and the liquid component, without heating and under reduced pressure, and in thermostatic vaporization, the reaction mixture can be separated into the vapor component and the liquid component. with heating (and reduced pressure). The reaction mixture can be separated into the vapor component and the liquid component, combining these vaporization conditions.
In instant distillation, the distillation temperature (or the reaction temperature) can, for example, be about 100 to 260 ° C (for example, about 110 to 250 ° C), preferably about 120 at 240 ° C (for example, from about 140 to 230 ° C), more preferably) from about 150 to 220 ° C (for example, from about 160 to 210 ° C) and, particularly, from about 170 at 200 ° C. In addition, in instant distillation, the temperature of the liquid catalyst mixture (or the liquid temperature of the reaction mixture) can be, for example, about 80 to 200 ° C (for example, about 90 to 180 ° C) preferably; from about 100 to 170 ° C (for example, from about 120 to 160 ° C) and, more preferably, from about 130 to 160 ° C. In addition, in instant distillation, the absolute pressure can be about 0.03 to 1 MPa (for example, about 0.05 to 1 MPa), preferably about 0.07 to 0.7 MPa and, more preferably, from about 0.1 to 0.5 MPa (for example, from about 0.15 to 0.4 MPa). Hydrogen iodide can be easily produced (or the concentration of hydrogen iodide tends to increase) under such a condition of relatively high temperature (and high pressure). According to the present invention, however, even under such a condition, since the production of hydrogen iodide in the carbonylation reaction is inhibited, the production or increase of the hydrogen iodide concentration in the instant evaporator can be efficiently inhibited.
The temperature and / or internal pressure in the vaporizer can be reduced, in comparison with those of the reactor, so that an additional production of by-products or reduced catalyst activity can be inhibited.
The separation (instantaneous distillation) of the metal catalyst component can generally be carried out using a distillation column (an instantaneous evaporator). In addition, the metal catalyst component can be separated by instant distillation in
combination with a method of mist collection, or by one method of collecting solids, which is widely used in applications industrial. The material of (or for form the) vaporizer not if
is particularly limited to a specific type ', and may include the same material as that of the carbonylation reactor. According to the present invention, due to the significant impediment of the elevation of the hydrogen iodide concentration inside the instantaneous evaporator, the corrosion of the instantaneous evaporator can also be inhibited to a high degree. Therefore, according to the present invention, for the instantaneous evaporator, an instantaneous evaporator made of the same material can also be used, which is a relatively inexpensive material having a not very high resistance to corrosion, such as that of the carbonylation reactor.
The step of separating the liquid catalyst mixture may consist of a single step, or it may be composed of a plurality of steps in combination. The mixture of liquid catalyst or catalyst component with the highest boiling point (metal catalyst component), separated by this step (s), can normally be recycled to the reaction system, as illustrated in the figure embodiment . In addition, the liquid catalyst mixture can be cooled (or removed from heat) by the heat exchanger and recirculated to the reactor, as shown in the example in the figure. Cooling can improve the efficiency of extracting heat from the entire system.
The separate liquid catalyst mixture! (Or low volatility component, or higher boiling fraction) contains the metal catalyst (for example, a rhodium catalyst), the ionic iodide (for example, an alkali metal iodide, such as lithium iodide) and, in addition, the remaining components without evaporation (for example, acetic acid, methyl iodide, water, methyl acetate, and hydrogen iodide).
In instant distillation (or instant evaporator), the ratio (weight ratio) of the volatile component to be separated in relation to the mixture of liquid catalyst (or low volatility component) can be about 10/90 to 50/50, preferably , from about 15/85 to 40/60
and, more preferably, about 20/80 at 35/65, in a proportion of the previous / later. According to the gift invention, among the components in the mix of catalyst liquid, The
The concentration of at least methyl acetate can be adjusted (or regulated). According to the present invention, the concentration adjustment and the inhibitory action against the production of hydrogen iodide in the carbonylation reaction are combined, so that the production or increase: of the hydrogen iodide concentration in the instant evaporator can be more efficiently inhibited in a wide range of instant reaction conditions. Multiple factors are involved in the reason why an increase in the concentration of hydrogen iodide is avoided by adjusting the concentration of methyl acetate, and one of the factors includes the consumption of hydrogen iodide by the next equilibrium reaction. By the way, the same equilibrium reaction is equally applicable to hydrogen iodide in the reaction mixture.
CH ₃ I + CH ₃ COOH <=> CH3COOCH3 + HI
The concentration of methyl acetate in the liquid catalyst mixture can be selected from the range of not less than 0.05% by weight (for example, from 0.1 to 20% by weight), which can, for example, be no less to 0.2% by weight (for example, from about 0.3 to 15% by weight), preferably not less than 0.5% by weight (for example, from about 0.6 to 10% by weight) weight) and, normally, from about 0.8 to 5% by weight (for example, from 1 to 4% by weight). In particular, the concentration of methyl acetate in the liquid catalyst mixture can be not less than 0.6% by weight (for example, from about 0.6 to 20% by weight), preferably not less than 0, 7% by weight (for example, from about 0.7 to 15% by weight), more preferably; not less than 0.8% by weight (for example, from about 0.8 to 10% by weight) and, normally, from 0.7 to 5% by weight (for example, from about 0.7 to 3% by weight, preferably from about 0.8 to 2% by weight and, more preferably, from about 0.9 to 1.5% by weight). The concentration of methyl acetate is adjusted for the range, so that the production or increase in the concentration of hydrogen iodide can be even more efficiently inhibited.
The water concentration in the liquid catalyst mixture can be, for example, selected from the range not exceeding 15% by weight (for example, from 0.1 to 12% by weight), and can be, for example, not exceeding to 10% by weight (for example, from about 0.5 to 10% by weight), preferably not more than 8% by weight (for example, from about 0.8 to 8% by weight) and, more preferably, no
more than 5% by weight (for example, in fence < from 1 to 4% in Weight).In addition concentration in acid acetic at catalyst mixture liquid can to be , per example, no less than 30% by weight (for example, in fence from 35 to 95%
by weight), preferably not less than 40% by weight (for example, from about 45 to 90% by weight) and, more preferably, not less than 50% by weight (for example, from about 50 to 85% by weight), and can generally be from about 60 to 90% by weight (e.g., from about 70 to 90% by weight and preferably from about 75 to 85% by weight).
In addition, the concentration of methyl iodide in the liquid catalyst mixture can be selected from the range of not more than 10% by weight (for example, from 0.001 to 8% by weight), and can be, for example, not more than 7% by weight (for example, from about 0.005 to 6% by weight), preferably not more than 5% by weight (for example, from about 0.01 to 4% by weight), more preferably, not more than 3% by weight (for example, from about 0.05 to 2.5% by weight), especially not more than 2% by weight (for example, from about 0.1 to 1.8% by weight) ), and can generally be from about 0.1 to 3% by weight (for example, from about 0.3 to 2.5% by weight, preferably from about 0.5 to 2% by weight) weight and, more preferably, from about 1 to 1.5% by weight).
In addition concentration ionic iodide ) at mix of catalyst liquid can be, for example, :no superior than 60% by weight (for example, of fence from 1 to 55 % in weight), preferably, not more than 50% by weight (per example, of fence 2 to 4 5% in Weight), more preferably not more than 40% by weight (for example,
from about 3 to 37% by weight) and especially not more than 36% by weight (for example, from about 5 to 35% by weight). Multiple factors are also involved in the reason why increasing the concentration of hydrogen iodide is avoided by adjusting the concentration of ionic iodide, and one of the factors includes the consumption of hydrogen iodide by the next equilibrium reaction. By the way, the same equilibrium reaction is equally applicable to hydrogen iodide in the reaction mixture.
MI + CH3COOH <=> CH3COOM + HI [In the formula, the symbol M represents a residue of an ionic iodide (or cationic group, for example, an alkali metal, such as lithium)]
By the way, the concentration of the metal catalyst in the liquid catalyst mixture can be, for example, not less than 70 0 ppm (for example, about 75 0 and 10000 ppm), preferably not less than 800 ppm ( for example, from about 850 to 5000 ppm) and, more preferably, not less than 900 ppm (for example, from about 950 to 3000 ppm) based on weight.
In addition, the concentration of methanol in the liquid catalyst mixture can be, for example, not more than 1% by weight (for example, from about 0 to 0.8% by weight), preferably not more than 0, 5% by weight (for example, from about 0 to 0.3% by weight) and, more preferably, not more than 0.3% by weight (for example, from about 0 to 0.2% by weight) ). As described later, when the concentration of methanol is higher, the concentration of methyl acetate in the liquid catalyst mixture is easily and efficiently increased.
The adjustment of the concentrations of the components in the liquid catalyst mixture (increase or decrease in concentration) is not particularly limited to a specific value, and the concentrations can be adjusted by the condition of instant distillation, the amount of the process solution to be recycled from next reaction (step (s)), and others. If necessary, in order to adjust the concentration of each component, a component to increase or decrease the concentration of each component [eg an ester (eg an ethyl ester), i an alcohol, and an ether] can be added to the reaction mixture and / or the instant evaporator. Such a component can be a component (basic component) reactive to hydrogen iodide.
For example, the concentration of methyl acetate in the liquid catalyst mixture can be efficiently increased by increasing the concentration of methanol in the reaction mixture (or in the liquid catalyst mixture). That is, as represented by the following general formula, methanol is allowed to react with acetic acid to produce methyl acetate (equilibrium reaction). Thus, the reaction of methyl acetate production occurs easily, when the concentration of methanol increases. As a result, the concentration of methyl acetate in the liquid catalyst mixture can be increased. By the way, the same equilibrium reaction is equally applicable to hydrogen iodide in the reaction mixture.
CH ₃ OH + CH3COOH <=> CH3COOCH3 + H ₂ 0
In the interval, in which the efficiency of acetic acid production is sufficiently guaranteed, the concentration of methanol can be increased by increasing the concentration of methanol to be fed in the reaction, or by decreasing the reaction rate to inhibit methanol consumption. The reaction speed can be adjusted by appropriately selecting the reaction temperature, the concentration of the catalyst (for example, the concentration of methyl iodide and the concentration of the metal catalyst), the concentration of carbon monoxide (or the partial pressure of carbon monoxide), and others. The methanol concentration can be adjusted, by directly adding methanol, as described later.
In addition, the concentration of methyl acetate in the liquid catalyst mixture can be adjusted by adding methyl acetate and / or a component to produce methyl acetate (for example, methanol and dimethyl ether). In this context, as described above, methanol is allowed to react with acetic acid to produce methyl acetate; and dimethyl ether is allowed to react with hydrogen iodide, or the like, to provide methanol, which is allowed to react with acetic acid to produce methyl acetate. If necessary, a component to increase or decrease the concentration of each component can be added or mixed in the form of a mixture containing a solvent.
When the elevator or reducer component is added to the reaction mixture, the position (or time) of addition is not particularly limited to a specific value, provided that the elevator or reducer component is added before the reaction mixture is fed to the instant evaporator. . The elevator or reducer component can be fed to the reactor. In terms of process efficiency, the elevator or reducer component can be fed to the reaction mixture, after the reaction mixture is discharged from the reactor, and before the reaction mixture is fed to the instant evaporator (for example, as shown in the figure, the elevator or reducer component can
be fed to a line to power the evaporator snapshot with the mixture in reaction discharged of reactor).Per other hand when the elevator component or
Reducer is added to the instant evaporator (or the elevator or reducer component is mixed with the reaction mixture in the instant evaporator), the position (height level j) of addition is not particularly limited to a specific value. The elevator or reducing component can be added to the liquid phase portion or to the gas phase portion in the flash evaporator, or to both. The elevator or reducer component can be added to the process solution to be recycled from the next step (s) to the instant evaporator.
The volatile component (acetic acid stream) separated in the vaporizer contains the acetic acid product, in addition to methyl iodide, an ester of the acetic acid product with methanol (eg methyl acetate), water, a small amount of by-product (s ) (for example, acetaldehyde and propionic acid) and others. The volatile component can be distilled in the first distillation column and the second distillation column, to produce purified acetic acid.
According to the present invention, the production or increase of the hydrogen iodide concentration in the vaporizer can be inhibited. Thus, the concentration of hydrogen iodide in the gas phase or volatile component inside the vaporizer can, for example, be set to no more than 1% by weight (for example, about Oi or detection limit at 8000 ppm), preferably at no more than 5000 ppm (for example, from about 1 to 4000 ppm) and preferably at no more than 3000 ppm (for example, from about 10 to 2,000 ppm) based on weight. In addition, the hydrogen iodide concentration in the liquid catalyst mixture can be, for example, regulated to no more than
1% by weight (for example, from about 0 to 8000 ppm), preferably not more than 5000 ppm (for example, from about 1 to
4000 ppm) and, more preferably, not more than 3000 ppm (for example, from about 10 to 2,000 ppm).
Part of the separate volatile component (acetic acid stream) can be introduced into a condenser or heat exchanger for cooling or extracting heat, just like the embodiment illustrated in the figure. Since the reaction heat transferred from the instant steam reaction solution can be partially cooled by heat extraction, the efficiency of heat extraction can be improved, and acetic acid with a high degree of purity can be produced without the installation of a refrigeration unit with external circulation in the reactor. In addition, the cooled volatile component can be recycled to the reaction system, just like the embodiment illustrated in the figure. On the other hand, the gaseous component in the cooled volatile component can be introduced into the washing system.
[Acetic acid collection step]
In the acetic acid collection step (distillation step), acetic acid is collected by separating a stream containing acetic acid from the volatile component. The method of separation is not particularly limited to a specific type. Typically, the separated volatile component is fed to the distillation column (dividing column), and separated into a lower boiling fraction (supernatant) containing a lower boiling component (eg, methyl iodide, acetic acid, acetate) methyl, and acetaldehyde by-product) and a stream containing acetic acid (acetic acid stream), by distillation. The acetic acid collection step, which is not necessarily the embodiment shown in the figure, and can be a step, in which a treatment to remove the component with the lowest boiling point and a treatment to extract water are carried out in a single distillation column (for example, a step using a distillation column described in Japanese Patent Publication No. 3616400), or a step, in which a treatment to remove the lowest boiling component and a treatment to extract water on a first distillation column it is followed by an additional purification step on a second distillation column. Considering the efficiency of the purification and others, a preferably usable step includes a distillation step, in which the treatment to extract the component with the lowest boiling point is carried out, essentially, in the first distillation column, and the treatment to extract water is essentially carried out on the second distillation column.
(First distillation column)
Part of the acetic acid stream (fraction of lowest boiling point) fed from the vaporizer is introduced into the heat exchanger, and the remaining (residual) acetic acid stream is fed to the first distillation column. In this context, the total quantity can be fed to the first distillation column without being introduced into the heat exchanger. In the first distillation column, a lower-boiling fraction (or first-lower-boiling fraction or first supernatant) containing at least part of a lower-boiling component (e.g. methyl iodide, methyl acetate, and acetaldehyde) and a higher boiling fraction (or bottom fraction) containing at least part of a higher boiling component (eg, propionic acid and water) are separated from the acetic acid stream, and a stream containing at least acetic acid is extracted. In the embodiment of Fig. 1, the chain containing acetic acid is extracted as a side chain by side cutting. The current containing acetic acid can be extracted from the bottom of the column.
As described above, the acetic acid stream fed to the first distillation column is not limited to an acetic acid stream obtained by extracting the rhodium catalyst component from the reaction mixture from the reaction system. The acetic acid stream can contain at least acetic acid, the component with the lowest boiling point, the component with the highest boiling point, and others; or it may simply be a mixture of these components.
For the first column used, for example, a conventional column, for example, a column like a plate column, or a filling column. The material of (or to form the) first distillation column can include the same material as that of the carbonylation reactor. According to the present invention, the production or increase of the hydrogen iodide concentration in the carbonylation reaction step, or in the instant distillation step, can be inhibited. Thus, for the first distillation column, a distillation column made of the same material, which is a relatively cheap material (for example, an alloy), such as that of the carbonylation reactor or the instant evaporator, can be used.
The distillation temperature and pressure in the first distillation column can be appropriately selected, depending on the condition, such as the species of the distillation column, or the main object (target) for extraction, selected from the lowest boiling point component and the component with the highest boiling point. For example, for the plate column, the internal pressure of the column (in general, the pressure at the top of the column) can be about 0.01 to 1 MPa, preferably about 0.01 to 0, 7 MPa and, more preferably, from about 0.05 to 0.5 MPa, in terms of gauge pressure.
In addition, in the first distillation column, the internal temperature of the column (in general, the temperature at the top of the column) can be adjusted by adjusting the internal pressure of the column, and can be, for example, from about 20 to 180 ° C, preferably, from about 50 to 150 ° C, and more preferably, from about 100 to 140 ° C.
In addition, for the plate column, the theoretical number of plates is not particularly limited to a specific value and, depending on the species of the component to be separated, is about 5 to 50, preferably about 7 to 3 5 and, more preferably, from about 8 to 30. In addition, in order to separate highly acetaldehyde (or with a high precision) in the first distillation column, the theoretical number of plates can be about 10 to 80, from preferably, from about 12 to 60, and more preferably, from about 15 to 40.
In the first distillation column, the reflux ratio can be selected, for example, from about 0.5 to 3000 and, preferably, from about 0.8 to 2000, depending on the theoretical number of plates mentioned above, or it can be reduced, increasing the theoretical number of plates. In this context, in the first distillation column, distillation can be carried out without reflux.
Since the lower boiling point fraction separated from the first distillation column contains a useful component (for example, methyl iodide and methyl acetate), the lower boiling point fraction can be directly recycled to the reaction (or reactor) and / or the first distillation column, or it can be liquefied by extracting heat from part of the reaction heat in the reaction system (for example, the reactor) with a condenser, a heat exchanger, or other medium and then recycled to the reactor and / or the first distillation column. For example, the fraction with the lowest boiling point extracted from the first distillation column does not need to be recycled to the first distillation column, after condensation by the condenser, as the embodiment of Fig. 1. The fraction of the lowest The extracted boiling point can be recycled directly, or simply cooled to remove a flue gas component (eg, carbon monoxide and hydrogen) and then the remaining (residual) liquid component can be recycled. In addition, among the components with the lowest boiling point in the fraction with the lowest boiling point, acetaldehyde deteriorates the quality of acetic acid as a final product. Thus, if necessary, after the extraction of acetaldehyde (for example, after the extraction of acetaldehyde, submitting the fraction containing the lowest boiling impurities to the acetaldehyde separation step mentioned below (acetaldehyde separation column)), remainder of the component (s) can be recycled to the reaction system and / or the first distillation column. In this context, the flue gas component can be introduced into the washing system.
The fraction with the highest boiling point (lower fraction or first fraction with the highest boiling point) separated in the first distillation column contains water, acetic acid, a dragged rhodium catalyst, lithium iodide, plus remaining acetic acid without being evaporated , the lowest boiling point impurities>
others. Thus, if necessary, the fraction of the highest point to be recycled to the reaction system (reactor) and / or the vaporizer. By the way, before recycling, propionic acid, which deteriorates the quality of acetic acid as a final product, can be removed.
In the second hydrogen column, a smaller component a higher point component from which it remains undivided, in the first distillation column, a column for example, a plate column, a filling column can be used. , and other columns. The material of (or forming the) second column of can include the same material as that of the first distillation column. According to the present invention, as for the second distillation column, a distillation column made of the same material, which is a relatively cheap material (for example, an alloy), such as that of the carbonylation reactor or evaporator, can be used. instant. In addition, the internal column temperature, the internal column pressure, the theoretical number of plates, and the reflux rate in the second distillation column can be selected, depending on the species of the distillation column, for example, can be selected at from the same range as that in the first column above.
Since the smaller supernatant) separated into the contains a useful component, such as methyl iodide or a lower boiling point, it can be directly recycled to the reaction system (for example, the reactor) and / or the second distillation column. In order to remove part of the reaction heat, in the same way as the lowest boiling point fraction extracted from the first distillation column, the lowest boiling point fraction can be liquefied by a condenser, a heat exchanger, or another medium and then recycled. In addition, since the lowest boiling point fraction sometimes contains acetaldehyde, the lowest boiling point fraction can be recycled, for example, after extraction of acetaldehyde with the aldehyde separation column, referred to below , if necessary. In this context, the flue gas component can be introduced into the washing system.
In addition, the fraction with the highest boiling point (second fraction with the highest boiling point) can be discharged from the bottom or bottom of the column. Since the fraction with the highest boiling point separated in the second distillation column contains propionic acid, and others, the fraction with the highest boiling point can be discarded directly (or removed). In addition, since the highest boiling fraction sometimes still contains acetic acid, if necessary, the highest boiling fraction, from which propionic acid is removed and / or recovered, can be recycled into the system. reaction (for example, the reactor).
In the second distillation column, the purified acetic acid stream is extracted by side cutting in the embodiment of Fig. 1. The position of the side stream opening can generally be a middle or bottom part of the distillation column, or the stream of acetic acid can be extracted from the bottom of the column. By the way, by extracting the acetic acid stream from the side current opening in a position higher than the bottom opening to extract the fraction with the highest boiling point, the side current and the fraction with the highest boiling point can be efficiently separated.
[Iodide extraction step]
The purified and recovered acetic acid is generally introduced into a column for the acetic acid product and obtained as the acetic acid product. Before or after introduction into the column for the acetic acid product, the purified acetic acid can be further subjected to an iodide extraction step to remove; an iodide (for example, a C1-15 alkyl iodide, such as hexyl iodide or decyl iodide).
In the iodide extraction step (or iodide removal step), the acetic acid stream can be contacted with a remover (material or removing agent) having an iodide removing or adsorbing capacity (for example, a zeolite, an activated carbon and a resin of the current iodide (in particular resin capacity, obtained, acetic acid, which is continuously a system
continuous), an resin of ion exchange with remover or adsorbent of iodide, in a column in extraction of endowed iodide gives ion exchange at the its inside it is advantageously
used.
generally ion exchange resin to an ion exchange resin to be used is (usually, a cation exchange), in which at least part of such as a sulfone group, a carboxyl group, a phenolic hydroxyl group, or a phosphone group) is replaced; or exchanged for a metal. The metal can include, for example, at least one element selected from the group consisting of silver (Ag), mercury (Hg) and copper (Cu). The cation exchange resin as a base (substrate) can be any one of strong acid cation exchange resin and weak (light) acid cation exchange resin, and the preferred one includes a strong acid cation exchange resin, for example, a resin macroreticular ion exchange, and the like.
In the ion exchange resin, the proportion of the active region exchanged with the metal (or replaced by the metal) can be, for example, about 10 to 80 mol%, preferably about 25 to 75% mol and , more preferably, from about 30 to 70 mol%.
At least the contact of the acetic acid stream from the second distillation column with the ion exchange resin (preferably, passage of the acetic acid stream through the ion exchange resin) performs the extraction of the iodide. During contact with (or passing through) the ion exchange resin, if necessary, the temperature of the acetic acid stream can be increased (or raised) gradually. The temperature rise in stages ensures the inhibition of spillage or flow of the metal from the ion exchange resin, as well as the removal of the iodide, efficiently.
Examples of the iodide extraction column may include a filling column containing at least the ion exchange resin that is exchanged with a metal, a column provided with a bed of an ion exchange resin (for example, a bed comprising a particulate resin) (a protective bed) and the like. The iodide extraction column can be provided with ion exchange resin, exchanged with metal and, in addition, another ion exchange resin (for example, a cation exchange resin, an anion exchange resin, and a non-exchange resin ionic) inside. Even when the metal is emanated from the ion exchange resin, exchanged for metal, the arrangement of the cation exchange resin on the downstream side of the ion exchange resin, exchanged for metal (for example, arrangement of the cation exchange resin by filling, or arrangement of the cation exchange resin as a resin bed) allows the effluent metal to be captured with the cation exchange resin and removed from the carboxylic acid stream.
The temperature of the iodide extraction column can be, for example, from about 18 to 100 ° C, preferably from about 30 to 70 ° C and, more preferably, from about 40 to 60 ° C.
The flow of the acetic acid stream to be passed is not limited to a specific value, and can be, for example, in an iodide extraction column using a protection bed, for example, from about 3 to 15 BV / h (bed volume per hour), preferably from about 5 to 12 BV / h, more preferably from about 6 to 10 BV / h.
In the iodide extraction step, the acetic acid stream can be contacted with the ion exchange resin, exchanged for metal. For example, the iodide extraction column may comprise a column with ion exchange resin, exchanged for metal, and a column with another ion exchange resin. For example, the iodide extraction column may comprise an anion exchange resin column, and an ion exchange resin column, exchanged for metal, on the downstream side of the anion exchange resin column, or it may comprise an ion exchange resin, exchanged for metal, and a column of cation exchange resin on the downstream side of the ion exchange resin column, exchanged for metal. The details of the previous example can be found in international patent W002 / 062740, and others.
[Acetaldehyde separation step]
When the fraction containing acetaldehyde generated by the reaction is recycled and distributed to the reaction system, the amount of by-product (s), such as propionic acid, an unsaturated aldehyde, or an alkyl iodide, increases. Thus, it is preferred to remove acetaldehyde in the solution to be recycled. In particular, extraction of acetaldehyde is preferred, as it is unnecessary to separate and remove propionic acid, which makes the acetic acid sub-standard in the second distillation column. The method for separating acetaldehyde may comprise feeding a recycling solution (a solution to be recycled) to the acetaldehyde separation column i, to separate a lower boiling fraction containing acetaldehyde, and a higher boiling fraction containing methyl iodide, methyl acetate, water, and others and then separate acetaldehyde from the top or top of the aldehyde separation column i, with the flue gas component (for example, carbon monoxide and hydrogen) . In addition, the flue gas component can be removed beforehand with a condenser or a cooling unit, prior to the separation of acetaldehyde. In addition, since the fraction with the highest boiling point obtained by extracting acetaldehyde as the fraction with the lowest boiling point contains methyl iodide, water, methyl acetate, acetic acid, and the like, the fraction with the highest boiling point can be recycled to the reaction system.
For the aldehyde separation column, for example, a conventional distillation column can be used, for example, a plate column, a filling column, an instant evaporator, and others.
The temperature (the temperature at the top of the column) and the pressure (the pressure at the top of the column)) in the acetaldehyde separation column can be selected, depending on the type of the distillation column and others, and are not particularly limited to values specific insofar as at least acetaldehyde is separable as a lower boiling point fraction from the recycling solution [e.g., the lower boiling point fraction (s) obtained in ( s) first and / or second distillation column (s)], using difference between acetaldehyde and other components (in particular, methyl iodide) at the boiling point. For example, for the plate column, the pressure can be from about 0.01 to 1 MPa, preferably from about 0.01 to 0.7 MPa and, more preferably, from about 0.05 to 0 , 5 MPa, as a gauge pressure. The internal temperature of the column is, for example, from about 10 to 150 ° C, preferably from about 20 to 130 ° C and, more preferably, from about 40 to 120 ° C. The theoretical number of plates can be, for example, from about 5 to 150, preferably from about 8 to 120 and, more preferably, from about 10 to 100.
In the acetaldehyde separation column, the reflux ratio can be selected from about 1 to 1000, preferably from about 10 to 800 and, preferably, from about 50 to 600 (for example, about 70 to 400), depending on the theoretical number of plates mentioned above.
EXAMPLES
The following examples are intended to describe the present invention in greater detail, and should in no way be construed as defining the scope of the invention.
Comparative Examples 1 to 8 and Examples 1 to 9
As shown in FIG. 1, an acetic acid production process was carried out continuously. The details of the process will be described below.
CO and methanol were fed to reactor 1, the process was started at a reaction temperature of 185 ° C and a reaction pressure of 2.8 MPa, and each composition of methyl iodide, water, methyl acetate, acid acetic, lithium iodide, and rhodium was adjusted to that shown in Table 1 (the methanol content was not higher than the detection limit). Then, the specimens of various materials shown in Table 1 were added to reactor 1. After standing for 100 hours, each specimen was examined by a corrosion test.
Corrosion test was evaluated based on the following criteria in Comparative Examples 1 to 4 and Examples 1 to 3, and evaluated about the observed amount of corrosion in Comparative Examples 5 to 8 and in Examples
THE : specimen not corroded at all. B : specimen severely corroded. Ç : slightly corroded specimen. D: significantly corroded specimen
The detail of the liquid composition and the results are shown in Tables 1 and 2. In Tables 1 and 2, ppm represents a concentration of Rh (rhodium) based on weight,% by weight means% by weight, STY represents a production rate of acetic acid, Ac represents acetic acid, MA represents methyl acetate, MeOH means methanol, Honey represents methyl iodide, Zr represents zirconium, HB2 represents a nickel-based alloy (HASTELLOY B2 manufactured by Oda Koki Co., Ltd.), HC represents a nickel-based alloy (HASTELLOY C manufactured by Oda Koki Co. Ltd.), the unit mol / L · h means the molar quantity (mol) of acetic acid produced in 1 L of the reaction solution per hour, and the unit mm / Y means the corrosion rate of the specimen per year (the decreased thickness (mm) of the specimen per year). In addition, in Table 2, it means that the amount of corrosion could not be measured, due to significant corrosion. As a Rh catalyst, Rhl ₃ was used. The iodide ion concentration derived from the iodide salt was subtracted from the total iodide ion concentration (I ') to calculate the hydrogen iodide concentration.
Corrosion test compositions and conditions Corrosion test results
CN (ti ι — I
d) X) (ti H
As evidenced from the tables, the corrosion of the specimens was avoided, adjusting the composition of the liquid in the carbonylation reactor to specific components and specific proportions. In particular, the corrosion of the specimens, made of a corrosive metal (such as HB2), has been significantly inhibited. In addition, in the instant distillation step, the hydrogen iodide concentration in the liquid catalyst mixture was maintained at less than 1% by weight: 0.4% by weight for Example 1, 0.4% by weight for Example 2, 0.1% by weight for Example 3, 0.4% by weight for Example 4, 0.4% by weight for
Example 5, 0.4% by weight for Example 6, 0.1% by weight for Example 7, 0.1% by weight for Example 8, and 0.15% by weight for Example 9.
Industrial Applicability
The production process of the present invention is extremely useful as a process for producing acetic acid, while at the same time efficiently inhibiting the production or increased concentration of hydrogen iodide in the carbonylation reactor.
Description of Reference Numbers · · · Reactor · · · Vaporizer (evaporator) · First distillation column · · · Second distillation column
5, 6, 7, 8, 9 ··· Condenser or heat exchanger · · · Washing system

权利要求:
Claims (13)
[1]
1. PROCESS TO PRODUCE ACETIC ACID, characterized by the fact that it comprises a reaction step, to allow methanol to continuously react with carbon monoxide in the presence of a catalyst system, comprising a metal catalyst, an ionic iodide, and methyl iodide, in a carbonylation reactor, in which, in the reaction step, the concentration of the metal catalyst is maintained from 880 to 3000 ppm, based on weight, the water concentration is maintained from 0.8 to 15% by weight, the concentration of Methyl iodide is maintained at no more than 13.9% by weight, and the concentration of methyl acetate is maintained from 0.6 to 4.1% by weight, in an integral liquid phase in the reactor.
[2]
2. PROCESS, according to claim 1, characterized by the fact that the production rate of acetic acid is not less than 10 mol / L · h.
[3]
3. PROCESS, according to claim 1, characterized by the fact that the production rate of acetic acid is not less than 19 mol / L · h.
[4]
4. PROCESS according to any one of claims 1 to 3, characterized in that, in the liquid phase in the reactor, the concentration of the metal catalyst is maintained from 900 to 3000 ppm based on weight.
[5]
5. PROCESS, according to any one of claims 1 to 4, characterized by the fact that, in the
Petition 870190002623, of 01/09/2019, p. 5/10 liquid in the reactor, the concentration of methyl acetate be maintained from 0.6 to 3.9% by weight.
[6]
6. PROCESS according to any one of claims 1 to 5, characterized in that, in the liquid phase in the reactor, the concentration of the metal catalyst is maintained from 900 to 3000 ppm based on weight, and the concentration of methyl acetate maintained from 0.6 to 3.9% by weight.
[7]
7. PROCESS, according to claims 1 to 6, characterized by the fact that, in the liquid phase in the reactor, the concentration of the metal catalyst is maintained from 900 to 3000 ppm based on weight, the water concentration is maintained from 0, 8 to 15% by weight, the ionic iodide concentration will be maintained at no more than 25% by weight, and the methyl iodide concentration will be maintained at 2 to 13.9% by weight.
[8]
8. PROCESS, according to any one of claims 1 to 7, characterized by the fact that the production rate of acetic acid is 10 to 45 mol / L · h and, in the liquid phase in the reactor, the concentration of the metal catalyst is maintained from 900 to 3000 ppm based on weight, the water concentration is maintained from 1 to 10% by weight, the ionic iodide concentration is maintained from 0.5 to 25% by weight, the methyl iodide concentration is maintained from 4 to 13.5% by weight, and the concentration of methyl acetate will be maintained from 1.8 to 3.9% by weight.
Petition 870190002623, of 01/09/2019, p. 6/10
[9]
9. PROCESS, according to any one of claims 1 to 8, characterized by the fact that the production rate of acetic acid is 19 to 35 mol / L · h and, in the liquid phase in the reactor, the concentration of the metal catalyst is maintained from 900 to 1500 ppm based on weight, the water concentration will be maintained from 1.5 to 9% by weight, the ionic iodide concentration will be maintained from 2 to 20% by weight, the methyl iodide concentration will be kept from 6 to 13% by weight, and the concentration of methyl acetate will be maintained from 1.8 to 3.9% by weight.
[10]
10. PROCESS, according to any one of claims 1 to 9, characterized by the fact that the reaction is carried out, maintaining a carbon monoxide pressure of at least 900 kPa and a hydrogen pressure of at least 4 kPa in the reactor.
[11]
11. PROCESS, according to any one of claims 1 to 10, characterized by the fact that it also comprises an instant distillation step for continuous supply of a vaporizer with a reaction mixture from the reactor, to evaporate a volatile component by instant distillation, the component volatile containing at least the
product acid acetic, acetate in methyl and iodide methyl, and stage acid collection acetic for separate one chain containing acetic acid of component volatile, and
Petition 870190002623, of 01/09/2019, p. 7/10 collect acetic acid, in which, in the instant distillation step, the reaction mixture is separated into the volatile component and a mixture of liquid catalyst containing at least the metal catalyst and ionic iodide, and the concentration of hydrogen iodide is maintained at not more than 1% by weight in the liquid catalyst mixture.
[12]
12. PROCESS according to any one of claims 1 to 11, characterized in that the material of the carbonylation reactor comprises a nickel-based alloy
[13]
13. METHOD FOR INHIBITING CORROSION OF A CARBONILATION REACTOR IN AN ACETIC ACID PRODUCTION PROCESS, characterized by the fact that the production process comprises a reaction step, to allow methanol to continuously react with carbon monoxide in the presence of a catalyst system , comprising a metal catalyst,
an ionic iodide, and iodide of methyl in the reactor carbonylation, where in step of reaction, the concentration of metal catalyst is maintained 880 to 3000 ppm, based on
by weight, the water concentration is maintained from 0.8 to 15% by weight, the methyl iodide concentration is maintained at no more than 13.9% by weight, and the methyl acetate concentration is maintained at 0, 6 to 4.1% by weight, in an integral liquid phase in the reactor.

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法律状态:
2018-10-30| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|

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2019-03-06| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2019-04-02| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 01/12/2011, OBSERVADAS AS CONDICOES LEGAIS. (CO) 20 (VINTE) ANOS CONTADOS A PARTIR DE 01/12/2011, OBSERVADAS AS CONDICOES LEGAIS |

优先权:

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申请号 | 申请日 | 专利标题

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JP2010-279797|2010-12-15|

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JP2010279797|2010-12-15|

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PCT/JP2011/077844|WO2012081416A1|2010-12-15|2011-12-01|Acetic acid production method|

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