• 专利附录
  • 专利说明
  • 权利要求
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    • 专利摘要:
    Use of an organic xerogel as a desiccant. The present invention relates to the use of an organic xerogel as a desiccant of high porosity and high oxygen content. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2635562A1
    申请号:ES201630261
    申请日:2016-03-04
    公开日:2017-10-04
    发明作者:J. Ángel MENÉNDEZ DÍAZ；Ana Arenillas De La Puente；Isabel DÍAZ ALONSO-BUENAPOSADA；Esther GÓMEZ CALVO；Natalia REY-RAAP；Miguel Ángel MONTES MORÁN
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；
    IPC主号:
    专利说明:

    The present invention relates to the use as desiccant of an organic xerogel,preferably a high porosity resorcinol Jformaldehyde xerogel (xerogel RF)and high oxygen content.
    STATE OF THE TECHNIQUE
    10 Organic gels are nanoporous materials obtained by the polymerization of hydroxylated benzenes and aldehydes in the presence of a solvent (see Pekala, R. Organic aerogels from the polycondensation of resorcinol with formaldehyde. JoumaJ ofMaterials Science 1989, 24, 3221-3227).
    15 Desiccant materials are hygroscopic solids that induce or maintain a dry state of the surrounding environment. In order to be considered as a good porous desiccant material, it not only has to be a hydrophilic material but it also needs to have a high water adsorption capacity (see Ng, E.
    20 P .; Mintova, S. Nanoporous materials with enhanced hydrophilicity and high water surprise capacity. Microporous and Mesoporous MateriaJs 2008, 114, 1-26). The hydrophilic capacity refers to its affinity for water, while its adsorption capacity depends mainly on the porosity. For example, some carbon-based materials considered hydrophilic show a
    High water adsorption capacity due to its surface chemistry rich in oxygenated groups, but its adsorption rate is low because its porosity is not adequate, so they cannot be considered as desiccants.
    Generally speaking, there are two types of desiccant materials: (i) substances
    30 whose behavior as a desiccant is due to a chemical hydration reaction, such as P4 0 10, MgS04; and (ii) substances whose desiccant behavior is based on surface interactions, such as adsorption processes, such as molecular sieves, silica gels, clays and starches (see for example, Iler, R. The chemistry of silica; solubility, polymerization, colloid and surface chemistry, and
    35 biochemistry. John Wiley & Sons, New York: 1979; and Breck, D.W. Zeolite molecular sieves: Structure. Chemistry and Use, WiJey, New York 1974, 636).
    Desiccants have been used over the past decades in a wide range ofapplications, with the aim of controlling humidity in the air when necessarya moisture-free environment, to control the level of water in gas streams5 industrial, in air conditioning systems, to store and protect thegoods in transport containers against moisture damage (Mathiowitz,
    AND.; Jacob, J.S .; Jong, Y.S .; Hekal, T.M .; Spano, W .; Guemonprez, R; Klibanov, A.M .; Langer, R. Novel desiccants based on designed polymeric blends. Journal of applied polymer science 2001, 80, 317-327).
    10 A general purpose desiccant is silica gel. Its good moisture adsorption capacity is due to its porous properties and the presence of hydroxyl groups on the surface that gives these materials hydrophilic nature. Water molecules are attracted by this oxygen-rich surface chemistry and
    15 stored in the pores of the material.
    Silica gel cannot be used to remove moisture in acidic media due to its sensitive structure.
    20 Therefore, it would be desirable to have a desiccant that allows moisture to be removed quickly and, therefore, has a high moisture absorption rate in addition to a high moisture absorption capacity; that is resistant to acids that may be present in the fluids to be treated; and that are structurally modifiable to eliminate other components apart from
    25 humidity.
    DESCRIPTION OF THE INVENTION
    As mentioned above, the present invention relates to the use as
    Desiccant of an organic xerogel, preferably an RF xerogel, of high porosity and large amount of oxygenated surface groups.
    Thus, in a first aspect, the present invention relates to the use of an organic xerogel as a desiccant, where:
    The average pore size of said organic xerogel is between 2 nm and 50 nm; and -the oxygen content of said organic xerogel is at least 25% by weight.
    In another embodiment the invention relates to the use defined above, where the total porosity is comprised between 60% and 70%.
    In another embodiment the invention relates to the use defined above, whereminus 55% of said porosity is due to pores whose pore size isbetween 2 nm and 50 nm.
    In another embodiment the invention relates to the use defined above, where 58% 10 of said porosity is due to pores whose pore size is between 2 nm and 50 nm.
    In another embodiment the invention relates to the use defined above, where the total porosity is 61%.
    In another embodiment the invention relates to the use defined above, where:-the total porosity is between 60% and 90%; Y-at least 50%, preferably 58%, of said porosity is due to pores whosePore size is between 2 nm and 50 nm.
    In another embodiment the invention relates to the use defined above, where.-the total porosity is between 60% and 70%; Y-at least 55% of said porosity is due to pores whose pore size isbetween 2 nm and 50 nm.
    In another embodiment the invention relates to the use defined above, where:-the total porosity is 61%; Y-58% of said porosity is due to pores whose pore size is comprisedbetween 2 nm and 50 nm.
    In another embodiment the invention relates to the use defined above, where the organic xerogel results from the polymerization, preferably from the microwave polymerization, between an aldehyde and a hydroxylated benzene.
    In another embodiment the invention relates to the use defined above, wherein the aldehyde is selected from formaldehyde and furfural.
    In another embodiment the invention relates to the use defined above, where the hydroxylated benzene is selected from resorcinol, phenol and catechol.
    In another embodiment the invention relates to the use defined above, where:-aldehyde is selected from formaldehyde and furfural; Y-hydroxylated benzene is selected from resorcinol, phenol and catechol.
    In another embodiment the invention relates to the use defined above, wherein the organic xerogel is selected from xerogel resorcinol / formaldehyde and xerogel phenol / formaldehyde.
    In another embodiment the invention relates to the use defined above, where the organic xerogel is a resorcinol / formaldehyde xerogel.
    In another embodiment the invention relates to the use defined above, where the polymerization is carried out at a pH between 4 and 8, and preferably at a pH of 5.8.
    In another embodiment the invention relates to the use defined above, where the resorcinol / formaldehyde xerogel is obtained by a microwave polymerization step of a mixture of resorcinol (R), formaldehyde (F), water and a catalyst.
    In another embodiment the invention refers to the use defined above, where the
    Resorcinolformaldehyde xerogel is obtained by a microwave polymerization step of a mixture of resorcinol (R), formaldehyde (F), water and a catalyst of a basic nature.
    In another embodiment the invention relates to the use defined above, where the
    Resorcinolformaldehyde xerogel is obtained by a microwave polymerization step of a mixture of resorcinol (R), formaldehyde (F), water and a catalyst of a basic nature; and said catalyst of a basic nature is inorganic, and is preferably selected from Na (OH), Na2C03, NaHC03, NH4N03 and NH4CI. The other embodiment of the invention relates to the use defined above, wherein the
    Xerogel resorcinol / formaldehyde is obtained by a microwave polymerization step of a mixture of resorcinol (R), formaldehyde (F), water and a catalyst of a basic nature; and said catalyst of a basic nature is organic, and is preferably selected from urea, melamine, pyrone, pyridine, methyl amine and dimethyl amine.
    In another embodiment the invention relates to the use defined above, where the molar ratio between resorcinol (R) and formaldehyde (F) is between 0.5 and 0.7, and preferably 0.5.
    In another embodiment the invention relates to the use defined above, where the organic xerogel is obtained after post-treatment in air at a temperature between 100 oC and 300 oC, and preferably at a temperature of 100 oC.
    Throughout the present invention, the term "desiccant" refers to a substance that is used to remove moisture from the air or other gaseous medium or from some other substance.
    The term "organic gel" refers to a solid polymer of an organic nature that is obtained by a sol-gel polymerization process of one or more precursors (monomers) of an organic nature, and subsequent removal of the solvent in which it has been carried out. carry out the polymerization.
    The term "organic xerogel" refers to a type of organic gel that is obtained at atmospheric pressure and at ambient temperatures (never negative and at a maximum of about 100 OC). Examples include any xerogel resulting from the polymerization between an aldehyde and a hydroxylated benzene (a benzene ring substituted in any of its available positions with one to four hydroxyl groups). Examples of aldehyde include among others resorcinol, phenal and cocatechol. Examples of aldehyde include among others furfural and formaldehyde.
    The term "xerogel RF" or "xerogel resorcinol / formaldehyde" refers to an organic gel obtained from the polymerization of resorcinol (R) and formaldehyde (F) in which the solvent is removed by evaporation, and preferably by removing the solvent by evaporation in microwave oven.
    The xerogels to which the invention relates have a kinetics, or adsorption rate, higher than that of silica gel, so it can be considered to be a desiccant that acts quickly.
    5 The term "porosity" or "fraction of holes" refers to the size of the spacesgaps in a material, and is a fraction of the volume of gaps over the total volumeof the material, expressed as a percentage between 0% and 100%. The porosity ofXerogels of the invention is between 60% and 90%, preferably between60% and 70% Y more preferably 61%.
    10 The term "catalyst of a basic nature" refers to a substance of organic or inorganic nature whose pH in aqueous solution is greater than 7. Examples of catalyst of inorganic nature include, among others, Na (OH), Na2C03, NaHC03, NH4N03y NH4CI. Examples of catalyst of an organic nature include, among others.
    Urea, melamine, pyrone, pyridine, methyl amine and dimethyl amine.
    The term "post-treatment in air" refers to a treatment at a temperature above 100 oC and below 300 oC, atmospheric pressure and air atmosphere, which is done after the synthesis of the xerogel. This post-treatment can be carried out in
    20 a conventional stove or any other type of device capable of raising the temperature of the material to the temperature of the post-treatment.
    Throughout the description and claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or
    25 steps For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.
    30 BRIEF DESCRIPTION OF THE FIGURES
    FIG. 1 shows the water vapor adsorption isotherms obtained at 25 oC and at a relative humidity (of air) of 100%
    EXAMPLES The invention will now be illustrated by tests carried out by the inventors, which show the effectiveness of the product of the invention.
    Synthesis of organic xerogels
    5 The organic xerogels used in this study were synthesized by the polymerization of resorcinol (R) and formaldehyde (F), using deionized water as the solvent and NaOH as the reaction catalyst. First, resorcinol (Indspec, 99.6%) was dissolved in deionized water using an unsealed glass cup and magnetic stirring until completely dissolved. Then, a solution was added
    10 of formaldehyde until a homogeneous solution is obtained. A solution of NaOH (0.1 M, Titripac, Merck) was added dropwise to adjust the desired pH. The proportion of each reagent is selected such that two different porosities are obtained (Table 1). The precursor solutions were placed in a microwave oven at 85 ° C for approximately 3 hours. During this time the
    15 polymerization and curing of the xerogels. Subsequently, the polymers were dried by heating in a microwave oven until a mass loss of more than 50% was recorded, which corresponds to the total removal of the solvent, the total synthesis time being less than 5 h. As a result, two were obtained. different organic gels (Table 2). Finally the xerogeles underwent a post
    20 air treatment at a temperature of 100 oC for one hour.
    Sample characterization
    Before any characterization, the xerogels were degassed (Micromeritics
    VacPrep 0.61) at 0.1 mbar and 120 oC overnight, in order to eliminate the
    25 moisture and other adsorbed gases.
    Porous properties The porosity of the studied samples was characterized by nitrogen adsorption-desorption isotherms and mercury porosimetry.
    The nitrogen adsorption-desorption isotherms were measured at -196 oC in a Tristar 3020 (Micromeritics). The SET surface was determined from the adsorption branch of N2 and, in all cases the number of points used to apply the SET equation was greater than 5. The volume of micropores (Vmicro) was estimated by the Dubinin method -Raduskevich. This method only includes micropore surfaces. Therefore, both techniques are complementary. The adsorption isotherms of N2 desorption were only used to obtain information about microporosity (BET surface, Vmicro). Parameters such as porosity (%), pore size distribution (PSD), bulk density and mesopore and macropore volumes (Vmeso, Vmacro), were determined by mercury porosimetry, 5 with AutoPore IV 9500 (Micromeritics) , which is capable of measuring from atmospheric pressure to 228 MPa. In the case of the characterization of mesopores, the lower limit of this equipment is 5.5 nm. Similarly, in this study, Vmacro refers to porosity that ranges from 50 to 10,000 nm. The surface tension and contact angle that were taken for mercury were
    10 485 mN m · 'and 1300 respectively, and the stem filling volume was between 45-58% in all the analyzes performed. Initially, at the low pressure stage, the samples were evacuated at 6.7 Pa and the equilibrium time used was 10 seconds. Subsequently, the pressure was gradually increased to the maximum value, mercury intrusion was evaluated.
    Elemental analysis The determination of C, H and N was carried out on a LECO CHNS-932 analyzer. The oxygen content was determined using the LECO VTF-900 analyzer
    20 Water vapor adsorption experiments The procedure to measure the water vapor adsorption capacity and kinetics consisted of placing 0.6 to 0.8 g of sample inside an airtight container at 25 oC and 100% humidity relative air and record mass changes over time to constant values.
    The RF xerogel is obtained in a process that comprises two stages. The first consists in the microwave polymerization of a mixture of resorcinol, formaldehyde, water and a catalyst. The obtaining of the organic xerogel in microwave is described in ES 2354782 "Procedure for obtaining organic xerogels of 30 controlled porosity". However, the precursor mixture that is subjected to this treatment has particular characteristics (pH greater than 5.5, solvent / reagent molar ratio between 5 and 9 and resorcinol / formaldehyde molar ratio less than 0.7). Otherwise, the resulting xerogels do not have adequate porosity (greater than 60% and with average pore sizes between 2 and 50 nm, that is,
    35 mesopores) that gives them great capacity for adsorption of ambient humidity.
    These characteristics of the precursor solution have been optimized and are not, therefore, evident a priori. For example, if the treatment is carried out outside the pH, resorcinol / formaldehyde and / or dilution ranges, the resulting porosity would not be adequate and the moisture adsorption capacity would decrease markedly. 5 For example, in Figure 1 the desiccant capacities of the xerogels named A and B are presented, as well as that of the silica gel taken as a reference. These desiccant capacities are expressed as the variation of the millimoles of water adsorbed per gram of material over time; at a temperature of 25 oC and under 100% relative humidity conditions. In the aforementioned Figure 10 it can be seen that xerogel B, despite having a porosity greater than xerogel A, its water vapor adsorption capacity is slightly higher than 10 milli moles per gram (18% by weight), compared to at almost 30 millimoles per gram (54% by weight) of xerogel A; that is, the latter has practically triple the adsorption capacity. It is seen, therefore, that if the xerogel is synthesized outside the 15 conditions described above its desiccant capacity is markedly lower.
    The second stage of the process of obtaining consists in a post-treatment in air at a temperature between 100 and 300 oC; although preferably 100 oC. This treatment aims to stabilize the xerogel. Further,
    20 also contributes to generating oxygenated surface groups that increase water adsorption capacity.
    The material has a desiccant capacity (adsorption of humidity of the environment) superior to that of silica gel (material taken as commercial desiccant of
    25 reference). For example, in Figure 1 it can be seen how the organic xerogel called A has an adsorption capacity close to 30 milliols per gram (54% by weight), while the adsorption capacity of silica gel under the same conditions is of only 14 millimoles per gram (25% by weight). That is, the desiccant capacity of the organic xerogel doubles that of the reference material.
    30 The average speed at which this adsorption occurs can represent, depending on the humidity and temperature conditions, 2 times that of silica gel. Thus, for example, in Figure 1 it can be seen how the time required to adsorb 10 millimoles of water is 75 hours for xerogel A, while the
    It takes 140 hours for silica gel to absorb the same amount of water. That is, xerogel A is almost 2 times faster than silica gel.
    It is an organic material resistant to acid attack, which differentiates it from most desiccant materials that are of inorganic nature, for example silica gel.
    5 The material has a porosity greater than 60% while the porosity of the silica gel, for example, is around 30%. These data are shown in Table 2. This difference in total porosity results in a material with greater desiccant capacity in the case of type A xerogel, as shown in the example in Figure
    10 1. This porosity is mainly composed of pores whose sizes are between 2 nm and 50 nm, also called mesopores. For example, in Table 2 it is shown as in the case of xerogel A 58% of the total porosity are mesopores. A lower percentage of mesopores, although the total porosity is higher, results in a material with a desiccant capacity markedly lower than
    15 of the material described in this patent. Case, for example of xerogel B. This is illustrated in the example presented in Figure 1.
    Microporosity, even though it is a factor with some influence, is not a relevant factor for a good desiccant, since type A gel and silica gel have 20 similar micropore volume values and specific superture: 0.1 cm3g and 300 m2¡g for both materials.
    Table 1. Synthesis conditions of xerogels A and B
    Xerogel A B pH 5.6 4.6molar ratio molar ratio Solvent capacity / reagents resorcinollformaldehyde desiccant 6.4 0.5> silica gel 6.0 0.70 <silica gel
    Table 2. Porous and chemical characteristics of desiccant xerogel (A), a xerogel that is not a good desiccant (B), a reference desiccant material (silica gel)
    Material % Porosity% of pores with sizes between 2 nm and 50 nm%C% H% 0% Inorganic impurities
    TO 615664.64.930.3<0.1
    B 69OR66.34,529.2<0.1

    Silica gel I31 150 1 -I 53.3 Not applicable
    The material consists mostly of carbon, which is always in a proportion greater than 60%. It also has a significant amount of oxygenated surface groups, with an oxygen content always exceeding 25 5% by weight. This characteristic favors the adsorption of water molecules. The material also has a small hydrogen content, in amounts between 4 and 5%. It is important to mention that no type of inorganic remains have been detected, so the level of impurities of this material is less than 0.1% by weight. Table 2 shows the chemical characteristics of the xerogel
    10 called A. The chemical characteristics of the xerogel called B are similar; However, its different porous texture makes this material not a good desiccant. Therefore, for the material to have good characteristics as a desiccant, the appropriate combination of chemical and porous properties is necessary.
    15 The material has a good consistency and can be obtained in granular form or even in the form of shaped monoliths. It can also be ground and presented as a fine powder, and can thus be incorporated into inks, paints or other media that allow its application to surfaces or even be used in
    20 additive manufacturing.
    权利要求:
    Claims (13)
    [1]
    1. Use of an organic xerogel as a desiccant, where: - the average pore size of said organic xerogel is between 2 nm and 50 nm; and -the oxygen content of said organic xerogel is at least 25% in
    5 weight
    [2]
    2. The use according to claim 1, wherein: the total porosity is comprised between 60% and 90%; and -at least 50% of said porosity is due to pores whose pore size is
    10 between 2 nm and 50 nm.
    [3]
    3. The use according to any of claims 1 or 2, wherein the total porosity is comprised between 60% and 70%.
    The use according to any one of claims 1 to 3, wherein at least 55% of said porosity is due to pores whose pore size is between 2 nm and 50 nm.
    [5]
    5. The use according to claim 4, wherein 58% of said porosity is due to pores whose pore size is between 2 nm and 50 nm.
    [6]
    6. The use according to any of claims 1 to 5, wherein the total porosity is 61%.
    The use according to any one of claims 1 to 6, wherein the organic xerogel results from the polymerization between an aldehyde and a hydroxylated benzene.
    [8]
    8. The use according to claim 7, wherein the aldehyde is selected from formaldehyde
    and fury! 30
    [9]
    9. The use according to any of claims 7 or 8, wherein the hydroxylated benzene is selected from resorcinol, phenal and catechism!
    [10]
    10. The use according to any one of claims 1 to 7, wherein the organic xerogel is selected from resorcinol / formaldehyde xerogel and phenol / formaldehyde xerogel.
    [11 ]
    eleven . The use according to claim 10, wherein the organic xerogel is a resorcinollformaldehyde xerogel.
    [12]
    12. The use according to claim 7, wherein the polymerization is carried out at a pH between 4 and 8.
    [13]
    13. The use according to claim 12, wherein the polymerization is carried out at a pH of 5.8,
    The use according to any of claims 7 to 13, wherein the molar ratio between the aldehyde and the hydroxylated benzene is between 0.5 and 0.7.
    [15]
    fifteen. The use according to claim 14, wherein the molar ratio between the aldehyde and hydroxylated benzene is 0.5.
    [16]
    16. The use according to any of claims 1 to 15, wherein the organic xerogel is obtained after post-treatment in air at a temperature between 100 oC and 300 oC
    The use according to claim 16, wherein the organic xerogel is obtained after a post-treatment in air at a temperature 100 oC.
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    同族专利:
    公开号 | 公开日
    ES2635562B1|2018-07-12|
    WO2017149189A1|2017-09-08|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    ES2354782B1|2009-06-03|2012-01-31|Consejo Superior De Investigaciones Científicas |PROCEDURE FOR OBTAINING ORGANIC XEROGELS OF CONTROLLED POROSITY.|
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    PCT/ES2017/070120| WO2017149189A1|2016-03-04|2017-03-03|Use of an organic xerogel as a desiccant|
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