A kind of preparation process of 12-hydroxystearic acid

Abstract

The present invention provides a preparation process of 12-hydroxystearic acid, and the preparation process of the 12-hydroxystearic acid comprises the following steps: S1, refining of castor oil; S2, hydrogenation of refined castor oil; S3, saponification; S4, acidification; S5, post-treatment. The preparation process of 12-hydroxystearic acid provided by the present invention has the characteristics of low cost, high safety, high yield, high purity and high quality, can be widely used in the technical field of stearic acid preparation process, and has good commercial application value.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical intermediate preparation technology, specifically to the technical field of stearic acid preparation technology, and particularly to a preparation technology of 12-hydroxystearic acid. Background Art

[0002] 12-Hydroxystearic acid, also known as dodecylhydroxystearic acid or 12-hydroxy-octadecanoic acid, is an important organic synthesis intermediate. Its main use is in the production of calcium-based and lithium-based lubricants. With the anti-war movement in the domestic lubricant industry, the demand for 12-hydroxystearic acid has increased year by year, and higher requirements have been placed on its quality.

[0003] At present, 12-hydroxystearic acid is generally produced using castor oil as raw material. Castor oil is the only natural oil containing a large amount of branched acid, and its main component is ricinoleic acid. Castor oil can be selectively hydrogenated to obtain hydrogenated castor oil. 12-hydroxystearic acid can be obtained by controlling the hydroxyl group and undergoing saponification and acidolysis. The preparation process is relatively simple and mature. However, the preparation process of 12-hydroxystearic acid still has some defects. For example, the active ingredient used to prepare 12-hydroxystearic acid in the raw material castor oil is ricinoleic acid, which accounts for about 90% of the castor oil, and there are about 10% of free fatty acids and gum and other components, which makes the purity of the prepared 12-hydroxystearic acid low. In addition, the color of castor oil itself is dark, which will greatly reduce the quality of the obtained 12-hydroxystearic acid. In addition, high-purity H2 is often required as a hydrogen donor and heavy metal substances as catalysts in the hydrogenation process of castor oil, which greatly increases the preparation cost of 12-hydroxystearic acid, and high-purity H2 will also have certain safety hazards.

[0004] Patent CN 103288627A discloses a method for preparing 12-hydroxystearic acid using hydrogenated castor oil as a raw material. The application uses hydrogenated castor oil as a raw material, and obtains 12-hydroxystearic acid through saponification, acid washing, water washing, dehydration, slicing and other steps. Compared with the traditional method, the application adds a decolorization step after water washing, thereby improving the product quality, but does not solve the problems of low purity of castor oil and high cost and potential safety hazards caused by the use of H2 and metal catalysts; Patent CN 1473199A discloses a method for preparing 12-hydroxystearic acid. The application uses one or more enzymes to catalyze and hydrolyze natural fats or oils to form ricinoleic acid, and then performs catalytic hydrogenation and other operations to prepare 12-hydroxystearic acid. The application uses enzymatic hydrolysis to solve the problem of low purity of castor oil, but still does not solve the problems of high cost and potential safety hazards caused by the use of H2 and metal catalysts.

[0005] Therefore, there is an urgent need on the market for a preparation process for 12-hydroxystearic acid with low cost, high safety, high yield, high purity and high quality. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention selects castor oil as raw material, optimizes the synthesis steps and reaction conditions based on the processes of hydrogenation, saponification and acidification, and solves the problems of low purity, low quality, high cost and potential safety hazards in the existing preparation process of 12-hydroxystearic acid.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In one aspect, the present invention provides a process for preparing 12-hydroxystearic acid, comprising the following steps:

[0009] S1, refining of castor oil: refining crude castor oil by alkali, washing, decolorizing with solid decolorizing agent, deodorizing and dehydrating to obtain refined castor oil for standby use, wherein the solid decolorizing agent is prepared from cigarette ash and coal tar;

[0010] S2, hydrogenation of refined castor oil: add citric acid, a catalyst and an organic solvent to the refined castor oil obtained in step S1, carry out hydrogenation reaction at 175-180° C. and normal pressure to obtain hydrogenated castor oil for standby use;

[0011] S3, saponification: add alkali solution to the hydrogenated castor oil obtained in step S2, adjust the pH to 12-14, stir for 10-20 minutes, and obtain saponified product for use.

[0012] Wherein, the alkali solution is sodium hydroxide solution;

[0013] S4, acidification: add dilute sulfuric acid to the saponified product obtained in step S3, adjust the pH to 1-2, stir for 10-20 minutes, and obtain an acidified product for use;

[0014] S5, post-processing: washing, dehydrating and slicing the acidified product obtained in step S4 to obtain 12-hydroxystearic acid.

[0015] In some embodiments of the present invention, the specific method of refining castor oil in step S1 comprises the following steps:

[0016] (1) Alkali refining: heat crude castor oil to 55-65°C, add 10-20wt% sodium hydroxide solution, stir for 15-20min, raise the temperature to 75-85°C when the oil soap begins to separate, add salt water, raise the temperature to 90-100°C, let stand for precipitation for 40-50min, discharge the waste water to obtain product 1 for standby use,

[0017] The concentration of the saline solution is 1-2 wt %, and the mass ratio of the crude castor oil to the saline solution is 1:(0.2-0.4);

[0018] (2) Washing: The product 1 obtained in step (1) is washed with deionized water until the pH value is 6.5-7.5, and then subjected to rotary evaporation for 10-20 min to obtain the product 2 for later use;

[0019] (3) Decolorization with a solid decolorizing agent: Add a solid decolorizing agent to the product 2 obtained in step (2), stir at 90-100° C. for 20-40 min, filter while hot, and obtain a product 3 for later use;

[0020] (4) Deodorization: Steam is introduced into the product 3 obtained in step (3), and vacuum deodorization is performed at 170-190° C. for 2-3 h, and the product 4 is obtained after cooling to 85-90° C., releasing the vacuum, and filtering to obtain the product 4 for later use;

[0021] (5) Dehydration: The product 4 obtained in step (4) is subjected to rotary evaporation for 10-20 min to obtain refined castor oil.

[0022] In some embodiments of the present invention, the mass ratio of the crude castor oil to the sodium hydroxide solution in step (1) is 1:(0.6-0.8); the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent in step (3) is 1:(0.05-0.09).

[0023] Preferably, the mass ratio of the crude castor oil to the sodium hydroxide solution in step (1) is 1:0.7; and the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent in step (3) is 1:0.07.

[0024] In some embodiments of the present invention, the method for preparing the solid decolorizing agent in step (3) comprises the following steps:

[0025] The fly ash and coal tar pitch are mixed and placed in a reaction container, ground for 10-15 minutes, and calcined at 800-900° C. for 2-3 hours to obtain a solid decolorizing agent, wherein the mass ratio of the fly ash to the coal tar pitch is 1:(15-20).

[0026] Preferably, the method for preparing the solid decolorizing agent in step (3) comprises the following steps:

[0027] The fly ash and coal tar pitch were mixed and placed in a reaction container, ground for 13 minutes, and calcined at 850° C. for 2.5 hours to obtain a solid decolorizing agent, wherein the mass ratio of the fly ash to the coal tar pitch was 1:18.

[0028] In some embodiments of the present invention, the mass ratio of the refined castor oil obtained in step S1, citric acid and catalyst in step S2 is 1:(4-6):(0.6-1.0).

[0029] Preferably, in step S2, the mass ratio of the refined castor oil obtained in step S1, citric acid and catalyst is 1:5:0.8.

[0030] Chroma, as the main performance index of lubricating oil, determines the quality of lubricating oil. The pigment components in castor oil mainly contain impurities such as phospholipids, mucus and protein, which not only affect the stability of castor oil, but also affect the subsequent processing of 12-hydroxystearic acid. Traditional decolorization methods mainly include chemical oxidation and physical adsorption. Among them, the decolorizers commonly used in physical adsorption are activated carbon, diatomaceous earth, etc. Such decolorizers are expensive and have low adsorption when used in large quantities. The applicant selected almost cost-free ash as a solid decolorizer and realized the reuse of solid waste. On the one hand, the adsorption effect of the activated carbon component in the ash makes it have a good decolorization effect; on the other hand The potassium carbonate contained in the ash makes it weakly alkaline, so it can deacidify the free oleic acid in ricinoleic acid while decolorizing. Furthermore, the applicant mixes coal tar, which also has a good adsorption effect, with the ash. While improving the adsorption performance and decolorization, the quinoline insoluble matter in the coal tar interacts with the functional groups on the surface of the activated carbon component in the ash that has an adsorption effect, which can increase the number of micropores and surface area of ​​the activated carbon, and synergistically improve the adsorption performance and durability of the solid decolorizer. The quinoline insoluble matter can also serve as a carrier of activated carbon, thereby improving the adsorption performance and mechanical strength of the solid decolorizer, thereby making the 12-hydroxystearic acid have higher quality and purity.

[0031] In some embodiments of the present invention, the method for preparing the catalyst in step S2 comprises the following steps:

[0032] 1) stirring the NH4H2PO4 aqueous solution and the ZrOCl2·8H2O aqueous solution at 25-35° C. for 22-26 h, filtering, washing, and drying at 100-110° C. to obtain a reaction product for later use;

[0033] 2) Add the reaction product obtained in step 1) to anhydrous ethanol, stir, add PdCl2, Fe(NO3)2 and deionized water, stir at 25-35°C for 2.5-3.5h, dry at 100-110°C, and calcine to obtain the catalyst.

[0034] In some embodiments of the present invention, in step 1), the molar ratio of the NH4H2PO4 aqueous solution to the ZrOCl2·8H2O aqueous solution is 1:(1-2); in step 2), the mass ratio of the reaction product obtained in step 1), PdCl2 and Fe(NO3)2 is 1:(0.06-0.12):(0.5-0.7).

[0035] Preferably, in step 1), the molar ratio of the NH4H2PO4 aqueous solution to the ZrOCl2·8H2O aqueous solution is 1:1.5; in step 2), the mass ratio of the reaction product obtained in step 1), PdCl2 and Fe(NO3)2 is 1:0.09:0.6.

[0036] Zirconium oxide has the characteristics of high thermal stability, high specific surface area and low cost, and is a good choice as a hydrogenation reaction catalyst. On the one hand, the applicant uses NH4H2PO4 and ZrOCl2·8H2O to react to generate irregular granular product 1, and the phosphate and zirconium particles are coordinated to make product 1 have active sites, and by controlling the reaction ratio of the two, product 1 has excellent ion exchange capacity and a large number of active sites, so that it has good performance in supporting metal components; on the other hand, the applicant loads Pd and Fe bimetallic loading on product 1, so that the catalyst has both metal active sites and Lewis acid centers, which is beneficial to increase the activity of the catalyst, and the introduction of bimetallic increases the specific surface area and pore size of the catalyst, so that the catalyst can better enter the hydrogen donor and ricinoleic acid to initiate the hydrogenation reaction; further, the zirconium ion and the citrate in the hydrogen donor can be chelated, which can improve the stability of the catalyst; further, the divalent iron ion selected by the applicant has good reducibility, which can prevent oxidation during the hydrogenation process and improve the yield of the reaction.

[0037] In some embodiments of the present invention, the organic solvent in step S2 is at least one of ethanol, isopropanol, dioxane and tetrahydrofuran.

[0038] In some embodiments of the present invention, the diameter of the slice in step S5 is 2-5 mm.

[0039] Preferably, the diameter of the slice in step S5 is 3 mm.

[0040] In some embodiments of the present invention, the purity of 12-hydroxystearic acid prepared by the preparation process described in the above technical solution is not less than 99%, and the yield is not less than 97.5%.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention provides a preparation process of 12-hydroxystearic acid, which optimizes the synthesis steps and reaction conditions based on the processes of hydrogenation, saponification and acidification, so that the preparation process of 12-hydroxystearic acid is low-cost, high-safety, high-yield, high-purity and high-quality.

[0043] (2) In the solid decolorizing step of the castor oil refining of the present invention, the solid decolorizing agent is prepared from soot and coal tar, which not only achieves good decolorization but also has a deacidification effect. The synergistic effect between the soot and the coal tar makes the solid decolorizing agent have higher adsorption performance, durability and mechanical strength, thereby making the 12-hydroxystearic acid have higher quality and purity.

[0044] (3) The present invention introduces a catalyst based on zirconium oxide in the hydrogenation step of refined castor oil. Through the coordination reaction between phosphate and zirconium particles and the bimetallic loading of Pd and Fe, the catalyst has higher reaction activity, which is beneficial to improving the yield of 12-hydroxystearic acid.

[0045] (4) The purity of 12-hydroxystearic acid obtained by the preparation process of the present invention is not less than 99%, and the yield is not less than 97.5%. DETAILED DESCRIPTION

[0046] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0047] In the following examples, except for the solid decolorizing agent and the catalyst, the other compound monomers and related reagents used can be purchased from the market, among which crude castor oil was purchased from Shanghai Minyu New Material Technology Co., Ltd.; cigarette ash was collected from smoking rooms; and coal tar was purchased from Hebei Tanjiu Energy Technology Co., Ltd.

[0048] Preparation Example 1

[0049] The synthesis method of solid decolorizing agent A comprises the following steps:

[0050] 2 g of fly ash and 36 g of coal tar pitch were mixed and placed in a reaction container, ground for 13 min, and calcined at 850° C. for 2.5 h to obtain solid decolorizing agent A.

[0051] Preparation Example 2

[0052] Solid decolorizing agent B, the specific implementation method is the same as solid decolorizing agent A, the difference is: the mass of coal tar is replaced by 26g.

[0053] Preparation Example 3

[0054] Solid decolorizing agent C, the specific implementation method is the same as solid decolorizing agent A, except that: the mass of coal tar is replaced by 44g.

[0055] Preparation Example 4

[0056] The synthesis method of catalyst A comprises the following steps:

[0057] 1) Stir 0.05 mol 0.5 mol / L NH4H2PO4 aqueous solution and 0.075 mol 0.5 mol / L ZrOCl2·8H2O aqueous solution at 30°C for 24 h, filter, wash with deionized water 3 times, and dry at 105°C for 12 h to obtain a reaction product for use;

[0058] 2) Add 2 g of the reaction product obtained in step 1) to 80 ml of anhydrous ethanol, stir, add 0.18 g of PdCl2, 1.2 g of Fe(NO3)2 and 100 ml of deionized water, stir at 30°C for 3 h, dry at 105°C, and calcine at 500°C for 4 h to obtain catalyst A.

[0059] Preparation Example 5

[0060] Catalyst B, the specific implementation method is the same as that of catalyst A, except that: in step 1), the molar number of the ZrOCl2·8H2O aqueous solution is replaced by 0.04 mol.

[0061] Preparation Example 6

[0062] Catalyst C, the specific implementation method is the same as that of Catalyst A, except that: in step 2), the masses of PdCl2 and Fe(NO3)2 are replaced by 0.1g and 0.8g.

[0063] Example 1

[0064] A preparation process of 12-hydroxystearic acid comprises the following steps:

[0065] S1. Refining of castor oil:

[0066] (1) Alkali refining: 20 g crude castor oil was heated to 60° C., 14 g 15 wt % sodium hydroxide solution was added, and the mixture was stirred for 17 min. When the oil soap began to separate, the mixture was heated to 80° C., 6 g 1.5 wt % salt water was added, the mixture was heated to 100° C., and the mixture was allowed to stand for precipitation for 45 min. The waste water was discharged to obtain product 1 for later use.

[0067] (2) Washing: The product 1 obtained in step (1) was washed with deionized water until the pH value was 7.0, and then rotary evaporated for 15 min to obtain the product 2 for later use;

[0068] (3) Decolorization with solid decolorizing agent: Add solid decolorizing agent A to the product 2 obtained in step (2), stir at 95° C. for 30 min, filter while hot, and obtain product 3 for standby use.

[0069] Wherein, the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent A is 1:0.07;

[0070] (4) Deodorization: Steam is introduced into the product 3 obtained in step (3), and vacuum deodorization is performed at 180° C. for 2.5 h, cooled to 87° C., the vacuum is released, and filtered to obtain the product 4 for later use;

[0071] (5) Dehydration: The product 4 obtained in step (4) is subjected to rotary evaporation for 15 min to obtain refined castor oil for later use;

[0072] S2, hydrogenation of refined castor oil: add citric acid, catalyst A and 30 ml of isopropanol to the refined castor oil obtained in step S1, carry out hydrogenation reaction at 178° C. and normal pressure to obtain hydrogenated castor oil for standby use.

[0073] Wherein, the mass ratio of the refined castor oil, citric acid and catalyst obtained in step S1 is 1:5:0.8;

[0074] S3, saponification: add 30wt% sodium hydroxide solution to the hydrogenated castor oil obtained in step S2, adjust the pH to 13, stir for 15min, and obtain a saponified product for use;

[0075] S4, acidification: add 15wt% dilute sulfuric acid to the saponified product obtained in step S3, adjust the pH to 1.5, stir for 15min, and obtain an acidified product for use;

[0076] S5. Post-treatment: The acidified product obtained in step S4 is washed with water until pH=7, vacuum-dehydrated for 20 min, and sliced ​​to a diameter of 3 mm to obtain 12-hydroxystearic acid.

[0077] Example 2

[0078] A preparation process of 12-hydroxystearic acid comprises the following steps:

[0079] S1. Refining of castor oil:

[0080] (1) Alkali refining: 20 g crude castor oil was heated to 60° C., 12 g 15 wt % sodium hydroxide solution was added, and the mixture was stirred for 15 min. When the oil soap began to separate, the mixture was heated to 75° C., 4 g 1 wt % salt water was added, the mixture was heated to 90° C., and the mixture was allowed to stand for precipitation for 40 min. The waste water was discharged to obtain product 1 for later use.

[0081] (2) Washing: The product 1 obtained in step (1) was washed with deionized water until the pH value was 6.5, and then rotary evaporated for 10 min to obtain the product 2 for later use;

[0082] (3) Decolorization with solid decolorizing agent: Add solid decolorizing agent A to the product 2 obtained in step (2), stir at 95° C. for 30 min, filter while hot, and obtain product 3 for standby use.

[0083] Wherein, the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent A is 1:0.05;

[0084] (4) Deodorization: Steam is introduced into the product 3 obtained in step (3), and vacuum deodorization is performed at 170° C. for 2 h, cooled to 85° C., the vacuum is released, and filtered to obtain the product 4 for later use;

[0085] (5) Dehydration: The product 4 obtained in step (4) is subjected to rotary evaporation for 10 min to obtain refined castor oil for later use;

[0086] S2, hydrogenation of refined castor oil: add citric acid, catalyst A and 30 ml of isopropanol to the refined castor oil obtained in step S1, carry out hydrogenation reaction at 178° C. and normal pressure to obtain hydrogenated castor oil for standby use.

[0087] Wherein, the mass ratio of refined castor oil, citric acid and catalyst A obtained in step S1 is 1:4:0.6;

[0088] S3, saponification: add 30wt% sodium hydroxide solution to the hydrogenated castor oil obtained in step S2, adjust the pH to 12, stir for 10min, and obtain a saponified product for use;

[0089] S4, acidification: add 15wt% dilute sulfuric acid to the saponified product obtained in step S3, adjust the pH to 1, stir for 10 minutes, and obtain an acidified product for use;

[0090] S5. Post-treatment: The acidified product obtained in step S4 is washed with water until pH=7, vacuum-dehydrated for 20 min, and sliced ​​to a diameter of 2 mm to obtain 12-hydroxystearic acid.

[0091] Example 3

[0092] A preparation process of 12-hydroxystearic acid comprises the following steps:

[0093] S1. Refining of castor oil:

[0094] (1) Alkali refining: 20 g crude castor oil was heated to 60° C., 16 g 15 wt % sodium hydroxide solution was added, and the mixture was stirred for 20 min. When the oil soap began to separate, the mixture was heated to 85° C., 8 g 2 wt % salt water was added, the mixture was heated to 100° C., and the mixture was allowed to stand for precipitation for 50 min. The waste water was discharged to obtain product 1 for later use.

[0095] (2) Washing: The product 1 obtained in step (1) is washed with deionized water until the pH value is 7.5, and then rotary evaporated for 20 min to obtain the product 2 for later use;

[0096] (3) Decolorization with solid decolorizing agent: Add solid decolorizing agent A to the product 2 obtained in step (2), stir at 100° C. for 40 min, filter while hot, and obtain product 3 for later use.

[0097] Wherein, the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent A is 1:0.09;

[0098] (4) Deodorization: Steam is introduced into the product 3 obtained in step (3), and vacuum deodorization is performed at 190° C. for 3 h, then cooled to 90° C., the vacuum is released, and the product 4 is filtered to be used for later use;

[0099] (5) Dehydration: The product 4 obtained in step (4) is subjected to rotary evaporation for 20 min to obtain refined castor oil for later use;

[0100] S2, hydrogenation of refined castor oil: add citric acid, catalyst A and 30 ml of isopropanol to the refined castor oil obtained in step S1, carry out hydrogenation reaction at 178° C. and normal pressure to obtain hydrogenated castor oil for standby use.

[0101] Wherein, the mass ratio of the refined castor oil, citric acid and catalyst A obtained in step S1 is 1:6:1;

[0102] S3, saponification: add 30wt% sodium hydroxide solution to the hydrogenated castor oil obtained in step S2, adjust the pH to 14, stir for 20min, and obtain a saponified product for later use;

[0103] S4, acidification: add 15wt% dilute sulfuric acid to the saponified product obtained in step S3, adjust the pH to 2, stir for 20min, and obtain an acidified product for use;

[0104] S5. Post-treatment: The acidified product obtained in step S4 is washed with water until pH=7, vacuum-dehydrated for 20 min, and sliced ​​to a diameter of 5 mm to obtain 12-hydroxystearic acid.

[0105] Example 4

[0106] The present invention provides a preparation process of 12-hydroxystearic acid. The specific implementation method is the same as that of Example 1, except that the solid decolorizing agent A is replaced by the solid decolorizing agent B in equal amounts.

[0107] Example 5

[0108] The present invention provides a preparation process of 12-hydroxystearic acid. The specific implementation method is the same as that of Example 1, except that the solid decolorizing agent A is replaced by the solid decolorizing agent C in equal amounts.

[0109] Example 6

[0110] The present invention provides a preparation process of 12-hydroxystearic acid, and the specific implementation manner is the same as that of Example 1, except that catalyst A is replaced by catalyst B in equal amounts.

[0111] Example 7

[0112] The present invention provides a preparation process of 12-hydroxystearic acid, and the specific implementation manner is the same as that of Example 1, except that catalyst A is replaced by catalyst C in equal amounts.

[0113] Comparative Example 1

[0114] The present invention provides a preparation process of 12-hydroxystearic acid, and the specific implementation method is the same as that of Example 1, except that the solid decolorizing agent A is replaced by activated carbon.

[0115] Activated carbon was purchased from Suzhou Like Environmental Protection Technology Co., Ltd.

[0116] Comparative Example 2

[0117] The present invention provides a preparation process of 12-hydroxystearic acid, and the specific implementation method is the same as that of Example 1, except that the preparation steps of hydrogenation of refined castor oil in step S2 are as follows:

[0118] Under Ni catalysis, in a reactor, refined castor oil and H2 are subjected to hydrogenation reduction reaction in isopropanol to obtain a reaction liquid with a pressure of 0.10 MPa.

[0119] Performance Testing

[0120] The 12-hydroxystearic acid obtained in the above Examples 1-7 and Comparative Examples 1-2 was tested for purity and yield. The test results are shown in Table 1.

[0121] (1) The purity of 12-hydroxystearic acid was measured by gas chromatography;

[0122] (2) The yield is the ratio of the mass of 12-hydroxystearic acid finally obtained in step S5 to the mass of refined castor oil obtained in step S1.

[0123] Table 1

[0124] Group purity% Yield % Example 1 99.8％ 99％ Example 2 99.6％ 98.3％ Example 3 99.3％ 97.9％ Example 4 85.2％ 91.2％ Example 5 86.6％ 90.8％ Example 6 93.5％ 86.3％ Example 7 91.6％ 85.2％ Comparative Example 1 80.9％ 82.3％ Comparative Example 2 82.7％ 80.9％

[0125] As can be seen from the data in Table 1, the 12-hydroxystearic acid in Examples 1-3 of the present invention has the characteristics of high purity and high yield as a whole. Among them, Examples 4-5 change the proportion of the solid decolorant in the decolorization step of the solid decolorant in step S1, reduce the synergistic effect between the soot and the coal tar, and reduce the adsorption, durability and mechanical strength of the solid decolorant, thereby reducing the purity and yield of 12-hydroxystearic acid; Examples 6-7 change the main components of the catalyst in the hydrogenation process in step S2. The molar ratio of zirconium and phosphorus atoms and the loading amount of Pd and Fe bimetallics reduce the reaction activity of the catalyst, thereby causing the yield of 12-hydroxystearic acid to decrease significantly, and the influence on purity is relatively small; Comparative Examples 1-2 are respectively the solid decolorant decolorant of the refining of castor oil in step S1, and the solid decolorant A is replaced by activated carbon, and the hydrogenation of castor oil in step S2 is replaced by the traditional castor oil hydrogenation method, and the purity and yield of the prepared 12-hydroxystearic acid are found to be lower.

[0126] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing 12-hydroxystearic acid, characterized in that: The following steps are involved: S1, refining of castor oil: refining crude castor oil by alkali, washing, decolorizing with solid decolorizing agent, deodorizing and dehydrating to obtain refined castor oil for standby use, wherein the solid decolorizing agent is prepared from cigarette ash and coal tar; S2, hydrogenation of refined castor oil: add citric acid, a catalyst and an organic solvent to the refined castor oil obtained in step S1, carry out hydrogenation reaction at 175-180° C. and normal pressure to obtain hydrogenated castor oil for standby use; S3, saponification: add alkali solution to the hydrogenated castor oil obtained in step S2, adjust the pH to 12-14, stir for 10-20 minutes, and obtain a saponified product for use; S4, acidification: add dilute sulfuric acid to the saponified product obtained in step S3, adjust the pH to 1-2, stir for 10-20 minutes, and obtain an acidified product for use; S5, post-processing: washing, dehydrating and slicing the acidified product obtained in step S4 to obtain 12-hydroxystearic acid; The specific method of refining castor oil in step S1 comprises the following steps: (1) Alkali refining: heat the crude castor oil to 55-65°C, add 10-20wt% sodium hydroxide solution, stir for 15-20min, raise the temperature to 75-85°C when the oil soap begins to separate, add salt water, raise the temperature to 90-100°C, let stand for precipitation for 40-50min, discharge the waste water to obtain product 1 for standby use; (2) Washing: The product 1 obtained in step (1) is washed with deionized water until the pH value is 6.5-7.5, and then subjected to rotary evaporation for 10-20 min to obtain the product 2 for later use; (3) Decolorization with a solid decolorizing agent: Add a solid decolorizing agent to the product 2 obtained in step (2), stir at 90-100° C. for 20-40 min, filter while hot, and obtain a product 3 for later use; (4) Deodorization: Steam is introduced into the product 3 obtained in step (3), and vacuum deodorization is performed at 170-190°C for 2-3h, cooled to 85-90°C, the vacuum is released, and filtered to obtain the product 4 for standby use; (5) Dehydration: subjecting the product 4 obtained in step (4) to rotary evaporation for 10-20 min to obtain refined castor oil; The method for preparing the solid decolorizing agent in step (3) comprises the following steps: Mix the soot and coal tar pitch and place them in a reaction container, grind them for 10-15 minutes, and calcine them at 800-900°C for 2-3 hours to obtain a solid decolorizing agent, wherein the mass ratio of soot to coal tar pitch is 1:(15-20); The method for preparing the catalyst in step S2 comprises the following steps: 1) Stirring the NH4H2PO4 aqueous solution and the ZrOCl2·8H2O aqueous solution at 25-35°C for 22-26h, filtering, washing, and drying at 100-110°C to obtain a reaction product for use; 2) Add the reaction product obtained in step 1) into anhydrous ethanol, stir, add PdCl2, Fe(NO3)2 and deionized water, stir at 25-35°C for 2.5-3.5h, dry at 100-110°C, and calcine to obtain the catalyst.

2. The process for preparing 12-hydroxystearic acid according to claim 1, characterized in that: The mass ratio of the crude castor oil to the sodium hydroxide solution in step (1) is 1:(0.6-0.8); the mass ratio of the product 2 obtained in step (2) to the solid decolorizing agent in step (3) is 1:(0.05-0.09).

3. The preparation process of 12-hydroxystearic acid according to claim 1, characterized in that: In step S2, the mass ratio of the refined castor oil obtained in step S1, citric acid and catalyst is 1:(4-6):(0.6-1.0).

4. The preparation process of 12-hydroxystearic acid according to claim 1, characterized in that: In the step 1), the molar ratio of the NH4H2PO4 aqueous solution to the ZrOCl2·8H2O aqueous solution is 1:(1-2); in the step 2), the mass ratio of the reaction product obtained in the step 1), PdCl2 and Fe(NO3)2 is 1:(0.06-0.12):(0.5-0.7).

5. The process for preparing 12-hydroxystearic acid according to claim 1, characterized in that: The organic solvent in step S2 is at least one of ethanol, isopropanol, dioxane and tetrahydrofuran.

6. The process for preparing 12-hydroxystearic acid according to claim 1, characterized in that: The diameter of the slice in step S5 is 2-5 mm.

7. The preparation process according to any one of claims 1 to 6, characterized in that: The purity of the prepared 12-hydroxystearic acid is not less than 99%, and the yield is not less than 97.5%.