• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention refers to the use of carbon (unactivated) synthesized from the husks of the energetic cultivar of Pongamia pinnata as an adsorbent to reduce the content of free fatty acids present in the oils, serving as a stage prior to the transesterification reaction for the biodiesel production. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2857448A1
    申请号:ES202000041
    申请日:2020-03-11
    公开日:2021-09-28
    发明作者:Rodriguez Laura Diaz；Alayon Andrea Brito
    申请人:Universidad de La Laguna；
    IPC主号:
    专利说明:

    [0002] Energy farming coal for biodiesel production
    [0004] Technical sector
    [0006] The invention is within the field of Chemical Engineering, specifically it is related to adsorption processes.
    [0008] Background of the invention
    [0010] In recent decades, the need to generate biofuels as an alternative to fuels from fossil origin has favored the development of biodiesel production. It is a liquid biofuel capable of replacing diesel from a non-renewable source such as oil. However, efforts have focused on finding cheap raw materials (oils or fats) that do not compete with human food. The use of edible oils for the production of biodiesel, such as sunflower, soybean, olive oil, etc., are suitable since they have good physicochemical properties to be used in the transesterification reaction for the production of said biofuel. Specifically, they have a moderate viscosity and low acidity, that is, a low content of free fatty acids; however, the use of edible oils in the production of a fuel has been criticized.
    [0011] The use of non-edible raw materials, such as residual oils from food frying, or oils from energy crops are an alternative. The former have the advantage of their low cost as they are waste; the seconds are
    [0012] They are characterized by their toxicity, so they cannot be used for food. However, one of the main drawbacks of the production of biodiesel from inedible oils is the high content of free fatty acids that these oils present, since they prevent the transesterification reaction from being carried out adequately for the obtaining biofuel. This is due to the formation of soaps during the reaction, because the free fatty acids react with the basic catalyst (KOH or NaOH) conventionally used in industry in said reaction. As a consequence, a step prior to the transesterification reaction is required. This stage is based on an esterification reaction in which an acid is used as a catalyst, usually H2SO4, and the acidity of the oil is considerably reduced. However, homogeneous acid catalysts give serious contamination problems, since at the end of the reaction the catalyst has to separate, causing the cost of biodiesel production to increase. In addition, acids normally used as catalysts cause corrosion of equipment.
    [0014] There are multiple works that propose the esterification reaction as a solution to reducing the acidity of the oil before being subjected to the transesterification reaction for the production of biodiesel. However, there are very few who use the adsorption process as a solution to the problem of reducing high acidity in oils.
    [0015] Those who use the adsorption process prior to the transesterification reaction in the production of biodiesel generally use ion exchange resins. There are also works where an adsorbent is used to reduce the acidity of the oil, but not from the point of view of biodiesel production, only from the point of view of food.
    [0016] Other works use adsorption to purify the biodiesel obtained after the transesterification reaction.
    [0017] The document "FFA adsorption from waste oils or non-edible oils onto an anion exchange resin as alternative method to esterification reaction prior to transesterification reaction for biodiesel production" [1] uses a commercial anion exchange resin (Dowex 550A) to adsorb the acids Free fats present in oils, prior to the transesterification reaction for the production of biodiesel.
    [0019] The document “Adsorptive removal of saturated and unsaturated fatty acids using ion-exchange resins” [2] also uses different ionic resins (Indion 810, Indion 850 and Indion 860) for the adsorption of free fatty acids present in oils, in order to obtain an appropriate raw material for the production of biodiesel.
    [0021] The document "Adsorption of oleic acid from sunflower oil on Amberlyst A26 (OH)" [3] uses the exchange resin Amberlite A26 to remove oleic acid from sunflower oil by adsorption.
    [0023] The document "Adsorption of FFA in crude catfish oil onto chitosan, activated carbon, and activated earth: A kinetics study" [4] uses, among others, activated carbon with CO2 from walnut shell to adsorb free fatty acids from fish oil to turn it into an edible oil.
    [0025] The document “Deacidification effects of rice hull adsorbents as affected by thermal and acid treatment” [5] uses carbon obtained from the rice husk activated by an acid treatment to deacidify edible oils.
    [0027] Document US5597600 [6] discloses the use of magnesium silicate and an alkaline material to reduce the content of free fatty acids and to be able to reuse the oil for cooking.
    [0029] The document "Complete Utilization of Pongamia Pinnata: Preparation of Activated Carbon, Biodiesel and its purification" [7] synthesizes an adsorbent (activated carbon) from the cake obtained after the extraction of Pongamia pinnata oil from the seeds to purify the biodiesel obtained after the transesterification reaction. The document [7] studies parameters such as the density, viscosity and acid number of biodiesel. An improvement is observed in the density and viscosity values, since a reduction of the same is achieved; However, said activated carbon is not capable of reducing the acid number values of the biodiesel obtained, indeed, it increases it.
    [0031] References cited:
    [0032] [1] Díaz, L .; Brito, A (2014). FFA adsorption from waste oils or non-edible oils onto an anion exchange resin as an alternative method to esterification reaction prior to transesterification reaction for biodiesel production. Journal of Advanced Chemical Engineering 4: 2.
    [0033] [2] Maddikeri, G .; Pandit, A.B, Gogate, P.R (2012) Adsorptive removal of saturated and unsaturated fatty acids using ion-exchange resins. Industrial and Engineering Research 51: 6869-6876.
    [0034] [3] llgen, O. (2014) Adsorption of oleic acid from sunflower oil on Amberlyst A26 (OH). Fuel Processing Technology 118: 69-74.
    [0035] [4] S. Sathivel, W. Prinyawiwatkul. Adsorption of FFA in crude catfish oil onto chitosan, activated carbon, and activated earth: A kinetics study, J Am Oil Chem Soc, 81 (2004), pp. 493 496.
    [0036] [5] Yoon SH, Kim M, Gil B (2011) Deacidification effects of rice hull adsorbents as affected by thermal and acid treatment. Food Science and Technology 44: 1572-1576.
    [0037] [6] United States Patent 5597600 Treatment of cooking oils and fats with magnesium silicate and alkali materials.
    [0038] [7] Chaudhari, M .; Dhobale, A. (2014) Complete Utilization of Pongamia Pinnata: Preparation of Activated Carbon, Biodiesel and its purification, Int. J. ChemTech Res. 6 (7), 3672-3676.
    [0040] Throughout the description and the claims, the word "comprises" and its variants are not intended to exclude other technical characteristics. For the person skilled in the art, other aspects, advantages and characteristics of the invention will emerge in part from the description and in part of the practice of the invention.
    [0042] Explanation of the invention
    [0044] The present invention refers to the use of carbon (unactivated) synthesized from the husks of the energy culture of Pongamia pinnata as an adsorbent to reduce the content of 10 free fatty acids present in the oils, serving as a stage prior to the transesterification reaction to the production of biodiesel.
    [0046] The adsorption of free fatty acids on carbon from the husks of energy crops makes it possible to replace the esterification stage (a reaction that uses a strong acid as a catalyst, usually sulfuric acid) that is carried out prior to the transesterification reaction to produce biodiesel, with the Advantage that this entails: working at room temperature instead of 60-70 ° C or not using strong acids that corrode the equipment. Another advantage of free fatty acid adsorption on this type of carbon is that the oil obtained after adsorption does not have to be treated, it is used directly as raw material in the transesterification reaction to obtain biodiesel. In the case of esterification, the alcohol that has not reacted must be removed, as well as the remains of the acid catalyst.
    [0048] The choice of the husks of the energy crop as a base for the synthesis of carbon (which is used as an adsorbent) compared to other materials used as adsorbents in the elimination of free fatty acids is very advantageous, since it is residual biomass and allows to apply circular economy, giving value to a waste generated within the process itself and reducing biodiesel production costs considerably.
    [0050] Brief description of the drawings
    [0052] Figure 1. Infrared spectrum of charcoal obtained from Pongamia pinnata husks. The Y axis represents the transmittance in arbitrary units and the X axis represents the wave number in cm-1.
    [0054] Figure 2. Thermogravimetric analysis. TGA curve (in air) of the shells of Pongamia pinnata (dashed line) and of the charcoal (solid line) obtained from it. The X axis represents the temperature to which the sample is subjected (° C) and the Y axis represents the% loss of mass.
    [0056] Figure 3. X-ray diffraction pattern of carbon synthesized from Pongamia pinnata shells. The Y axis represents intensity in arbitrary units and the X axis represents angle 20 (°).
    [0057] Figure 4. Values of the BET surface and the mean pore diameter of the unactivated and activated carbons, obtained from the shells of Pongamia pinnata.
    [0058] Figure 5. Comparison of the free fatty acid adsorption capacity of the unactivated carbon object of the invention (solid line) and activated carbon (broken line), both obtained from the shells of Pongamia pinnata. The oil used in this comparison is a Jatropha curcas oil with an acid number of 3.4 mg KOH / g oil. The Y-axis represents the percentage of free fatty acid removal (%) and the adsorption time (minutes) on the X-axis.
    [0059] Figure 6. Reduction of the content of free fatty acids using two oils with high acidity: the solid line corresponds to an oil of Jatropha curcas with an acid number of 3.4 mg KOH / g oil), the broken line corresponds to an oil of Pongamia pinnata with an acid number of 9.2 mg KOH / g oil. The Y-axis represents the percentage of free fatty acid removal (%) and the X-axis the weight of adsorbent (carbon object of the invention) used with respect to the weight of the oil.
    [0060] Implementation of the invention
    [0061] The following example is provided by way of illustration, and is not intended to be limiting of the present invention.
    [0062] In a first embodiment of the invention, the unactivated carbon obtained from Pongamia pinnata husks and its synthesis procedure are described.
    [0063] Coal is obtained according to a procedure consisting of the following stages:
    [0064] 1) Crushing the shells of the seeds until obtaining a powdery material.
    [0065] 2) Calcination of the powdery material in a muffle at a temperature of at least 500 ° C. 3) Sieving the coal obtained to achieve a particle size of less than 0.250 mm. At no time is the activation of the carbon obtained carried out, neither by chemical nor physical treatment.
    [0066] The main physicochemical and structural characteristics of the synthesized unactivated carbon, object of the present invention, for the adsorption of free fatty acids as a stage prior to the transesterification reaction of oils for the production of biodiesel are shown in Figures 1-3.
    [0067] Figure 1 shows the infrared spectrum of the coal object of the invention. Strong bands can be distinguished in the wave number range 1600-400 cnr1. Most of them are attributed to characteristic functional groups of lignin. The peak that appears at 1375 cnr1 can be attributed to oxygen functionalities such as vibrations of C-0 and C = 0, the peak at 1058 cnr1 can be associated with vibrations of narrowing of C-0 present in alcohols, phenols, ethers and Asters, the IR band that appears at 618 cnr1 can be assigned to the deformation of the rings in the plane and the peak at 873 crrr1 can also be assigned to different vibration modes of CO.
    [0068] In the TGA curve (figure 2) a greater thermal stability of the coal is observed with respect to the uncarred shells, since it experiences a smaller loss of mass. The TGA curve for the shells of Pongamia pinnata reveals three distinct zones: the first between 30 180 ° C, corresponding to mass losses due to water evaporation, the second between 180-310 ° C, corresponds to the first carbonization from the degradation of hemicellulose and the third that occurs between 310-520 ° C and indicates the decomposition of cellulose and part of the lignin. The TGA curve of the coal object of the invention only experiences a loss of mass at a temperature above 400 ° C, which can be attributed to lignin that has not been decomposed at lower temperatures.
    [0070] The diffractogram (figure 3) shows the great crystallinity exhibited by the carbon object of the present invention. The appearance of peaks at 20 = 28 ° and 43 ° indicate the presence of carbonaceous crystalline structures such as graphite.
    [0072] The unactivated carbon synthesized from the shells of Pongamia pinnata is in the form of powder with a particle size of less than 0.250 mm and is characterized by presenting a low BET surface (figure 4) (as it is not subjected to any treatment of activation), crystalline phases of graphite and be composed of lignin (Figure 1-3).
    [0074] In another embodiment of the invention, the synthesized carbon is used in the adsorption process of oil-free fatty acids ( Pongamia pinnata oil, Jatropha curcas oil, etc.) at a temperature of 25 ° C, in a glass container. with magnetic stirring and compared to an activated carbon.
    [0076] To produce activated carbon, the seed shells were washed with water and dried at 110 ° C for 48 hours. The dried shells were ground in a ball mill and then calcined at 500 ° C for 1 hour. The material obtained was impregnated with a 1M NaOH solution at 70 ° C for 24 hours. Subsequently, the material obtained is dried at 110 ° C for 24 hours and subsequently activated at 600 ° C for 2 hours. Once the material cools, it is washed with a 1 M HCl solution and distilled water until a neutral pH is achieved. The washed powder was dried at 110 ° C for 24 hours and subjected to sieving, selecting a particle size less than 0.250 mm. Activated carbon shows a BET surface area of 312.84 m2g'1 and a pore diameter of 1.97 nm (Figure 4). The BET surface area is relatively low compared to other activated carbons, this is because the carbon was activated with a base rather than an acid.
    [0078] In the adsorption process, the oil to be deacidified, that is, reduce its acidity or free fatty acid content, is introduced into the glass container. When the oil is at a temperature of 25 ° C, the adsorbent (unactivated / activated carbon) is introduced and stirred for a certain time.
    [0079] At the end of the established time, the adsorbent is separated from the oil and its acid number is measured. This value is compared with the initial acid number of the oil, that is, before being subjected to the adsorption process. Unactivated carbon has a higher adsorption capacity compared to the same activated carbon when used as an adsorbent; With it, it is possible to obtain high percentages of reduction of free fatty acids and even reduce it to zero in certain oils (figure 5).
    [0080] It is observed that the unactivated carbon is capable of reducing 70% of the content of free fatty acids present in the oil after 120 minutes; for the same time, the activated carbon is only capable of reducing 4% of the free fatty acids present.
    [0081] This is due to the fact that the unactivated carbon is mesoporous (mean pore diameter 6.07 nm, figure 4), so free fatty acid molecules (mean size of the molecule is greater than 2nm) can freely access the interior. of the pores. Active carbons have a larger BET surface area and, therefore, pore diameters always less than 2 nm, which is why they are not suitable for the adsorption of this type of molecules. Therefore, the use of coal does not Activated is advantageous, as it has better adsorbent properties for this type of molecules and only requires calcination without any other physical or chemical treatment, typical of activated carbons. The elimination of the activation stage also saves money and time.
    [0083] In another embodiment of the invention, the use of the proposed coal is proposed as an alternative stage to the esterification reaction to obtain biodiesel by reducing the content of free fatty acids using two high-acid oils.
    [0085] The high percentages of reduction of free fatty acids obtained through the adsorption process with this carbon, using various oils and working at room temperature indicate the effectiveness of the new synthesized adsorbent (figure 6).
    [0086] It is observed that with 0.09 grams of carbon per gram of Jatropha curcas oil, a 100% reduction in the content of free fatty acids is achieved. With Pongamia pinnata oil, for the same adsorbent dose a reduction of the free fatty acid content of 77% is achieved. This reduction in acidity is sufficient to subsequently carry out the transesterification reaction with said oil to obtain biodiesel without generating soaps. The time used in the adsorption is 150 minutes.
    [0087] This adsorption process serves as a stage prior to the transesterification reaction to produce biodiesel, very advantageously replacing the currently used process, the esterification reaction. It is characterized by being a simple and cheap process, since the adsorbent is obtained from a residue, the shells of a seed. In addition, the carbon synthesis process (adsorbent) is also simple and does not require any chemical or physical activation. Furthermore, this process avoids the use of homogeneous acid catalysts, such as sulfuric acid, currently used to carry out the esterification reaction prior to the transesterification reaction.
    权利要求:
    Claims (4)
    [1]
    1. Unactivated carbon from Pongamia pinnata seeds with a particle size of less than 0.250 mm, a BET surface area of between 2 and 50 m2 g1 and a mean pore diameter in the mesopore range (2-50 nm).
    [2]
    2. Process for obtaining coal according to claim 1, which consists of the stages of crushing Pongamia pinnata shells, calcining at a temperature of at least 500 ° C and subsequent sieving, reaching a particle size of less than 0.250 mm.
    [3]
    3. Use of carbon according to claims 1-2 as an adsorbent to reduce free fatty acids present in oils.
    [4]
    4. Free fatty acid adsorption process comprising the use of carbon according to claims 1-3 as an alternative step to the esterification reaction to obtain biodiesel.
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