A method for preparing solvent-free hydrogenated dimer acid

Abstract

The invention discloses a method for preparing a solvent-free hydrogenated dimer acid, which uses common dimer acid as a raw material, does not add any solvent, uses a catalyst to carry out catalytic hydrogenation for 1-10 hours under the conditions of a reaction temperature of 100-250°C and a reaction pressure of 0.5-5.0MPa, and obtains hydrogenated dimer acid by post-processing. Compared with the prior art, the invention has the following beneficial effects: 1. The technical scheme of the present application is that since no solvent is added, a device for removing solvent and an operating step for removing solvent are not required, so that the production process is simplified and the investment energy consumption is reduced; 2. The present application has mild operating process conditions, a green and environmentally friendly production process, excellent product quality, and good industrial application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of oil chemical finishing, and in particular to a method for preparing solvent-free hydrogenated dimer acid. Background Art

[0002] Hydrogenated dimer acid is an aliphatic saturated dimer acid composed of more than 32 carbon atoms. It contains a long-chain structure (1), a monocyclic structure (2) and a bicyclic structure (3). It is an important intermediate in the field of polymer materials. It is prepared by dimerizing oleic acid and then catalytically hydrogenating the double bonds in its molecules. The reaction equation is shown in formula (4).

[0003]

[0004]

[0005] Commonly used dimer acids are divided into ordinary dimer acids and high-purity dimer acids. The ordinary dimer acid contains about 2wt% of monoacid, about 80wt% of dimer acid, and the balance is about 18wt% of triacid. The high-purity dimer acid, wherein the content of dimer acid is> 95wt%, or even more than 98wt%. Compared with ordinary dimer acid, hydrogenated dimer acid is used to prepare resins, inks, hot melts, resin films, etc., whose thermal stability, light stability, chemical stability, color and physical and mechanical properties are significantly improved and enhanced, and its application is more extensive.

[0006] Among these materials, polyamide curing agents, polyesters, polyester polyols, ink resins, hot melt adhesives, color steel coatings, electronic materials and other fields are widely used. The application fields of other types of hydrogenated dimer acids are constantly expanding and are becoming a new hot spot for scientific research. For example, rocket propellants, drug sustained-release materials, bioremediation materials, polymer membrane materials and other aspects are playing an increasingly important role.

[0007] Foreign countries have carried out the development and research of hydrogenated dimer acid as early as the middle of the last century. my country started late, but there have been related reports in recent years.

[0008] U.S. Patent US62 / 190304 and Chinese Patent CN107725426A report that fully hydrogenated dimer acid can be used to produce transparent polyamide, which has low melt viscosity, low glass transition temperature, high heat resistance, low temperature flexibility, good adhesion, and the film produced has ultra-high tensile modulus and good UV resistance.

[0009] CN201910117760.3 discloses a continuous synthesis method of hydrogenated dimer acid, comprising the following steps: (1) dispensing the catalyst into N fixed-bed reactors connected in series; (2) preheating and vaporizing the dimer acid and solvent respectively and catalytically hydrogenating them in the gas phase, and condensing and filtering the reaction products to obtain a liquid mixture; and (3) removing the solvent from the hydride.

[0010] CN111036214A discloses a preparation method and application of a Ni-CNT catalyst for hydrogenated dimer acid production, comprising: step one: preparing a Ni-CNT catalyst for hydrogenated dimer acid production; step two: online activation of the Ni-CNT catalyst; step three: hydrogenation of dimer acid to generate hydrogenated dimer acid; step four: online separation of solvent.

[0011] CN107602371A discloses a method for preparing hydrogenated dimer acid, which comprises the following preparation steps: adding cottonseed oil dimer acid into a reaction kettle, adding a solvent and a catalyst in sequence, introducing hydrogen, adjusting the pressure and temperature, stirring until the iodine value is ≤8gI2 / 100g, completing the hydrogenation reaction, separating the catalyst, and removing the solvent to obtain hydrogenated dimer acid.

[0012] CN102618393A discloses a method for preparing hydrogenated dimer acid, which uses dimer acid or high-purity dimer acid as raw material, hydrogenates and separates the hydrogenated dimer acid in the presence of a solvent and a catalyst, or hydrogenates high-purity dimer acid, uses cyclohexane and other solvents to prepare a 40%-80% solution with the raw material dimer acid, and performs catalytic hydrogenation at 190-240°C, 3.0-6.0MPa, and a hydrogen purity of >99.9%. The hydrogenated product is subjected to two-stage distillation at normal pressure and vacuum to remove the solvent, so as to obtain the hydrogenated dimer acid.

[0013] The above patents all require the addition of solvents to hydrogenated dimer acid, which results in a long process flow, high investment and energy consumption, and relatively harsh process conditions. It is necessary to further develop new technologies to reduce investment and energy consumption and operational severity. Summary of the invention

[0014] In order to solve the problems mentioned in the above background technology, the present invention provides a solvent-free method for preparing hydrogenated dimer acid.

[0015] In order to achieve the above purpose, a solvent-free preparation method of hydrogenated dimer acid is provided, which uses ordinary dimer acid as raw material, does not add any solvent, uses a catalyst for catalytic hydrogenation for 1-10h at a reaction temperature of 100-250°C and a reaction pressure of 0.5-5.0MPa, and obtains hydrogenated dimer acid through post-treatment.

[0016] Preferably, the common dimer acid contains 1-4 wt% of monoacid, 77-83 wt% of diacid and the remainder is triacid.

[0017] Preferably, the catalyst is a palladium-carbon catalyst, containing 1-10wt% palladium and 40-60wt% water.

[0018] Preferably, the amount of the palladium-carbon catalyst used is 0.5-20wt% of the amount of ordinary dimer acid used, preferably 1.0-10wt%.

[0019] Preferably, the hydrogen used in the catalytic hydrogenation does not contain elements harmful to the palladium-carbon catalyst, including but not limited to sulfur and chlorine.

[0020] Preferably, the purity of the hydrogen is ≧90v%, preferably ≧95v%, and its source is selected from any one or more of hydrogen produced from natural gas, hydrogen produced from coal, and hydrogen produced from water electrolysis.

[0021] Preferably, the reaction temperature is preferably 120-220°C, more preferably 140-180°C; the reaction pressure is preferably 1.0-3.5MPa, more preferably 1.5-2.5MPa; the catalytic hydrogenation reaction time is preferably 2-6h, more preferably 3-4h.

[0022] Preferably, the catalyst is filtered by any one of centrifugal separation, plate filtration and membrane filtration, preferably by metal membrane filter filtration.

[0023] Preferably, the reactor used for catalytic hydrogenation is a batch stirred reactor or a continuous fixed bed reactor.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Since the technical solution of the present application does not require solvent, there is no need for a solvent removal device and solvent removal operation steps, which simplifies the production process and reduces investment and energy consumption;

[0026] 2. This application has mild operating process conditions, green and environmentally friendly production process, excellent product quality, and good industrial application prospects. DETAILED DESCRIPTION

[0027] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0028] In the present application, ordinary dimer acids 1, 2, 3, and 4 are ordinary dimer acids from different batches, and their iodine value, acid value, color, and content of monoacid, diacid, and triacid are slightly different.

[0029] At present, there are few domestic studies on hydrogenated dimer acid, mainly using solvent method. The inventors have conducted a more in-depth and detailed study on the research of hydrogenated dimer acid, and made a detailed comparison between the solvent method and the method without solvent. On the basis of the research on the 2L small reactor device, an enlarged test of the 30L reactor was carried out, and the test effect was good. The study shows that the experimental method and process conditions have a great influence on the effect of dimer acid hydrogenation, and it is very important to select appropriate process conditions.

[0030] Example 1: Test of Hydrogenated Dimer Acid without Adding Solvent

[0031] Divide into several groups, add 200g common dimer acid and 10g Pd / C catalyst (containing 5wt% palladium and 45wt% water) into a 2L hydrogenation autoclave, evacuate and replace the air with nitrogen, then fill with hydrogen with a purity greater than 90v%, maintain the reaction pressure at 1.0-2.5MPa, stir the reaction at 160-180℃ for 3h, stop stirring, cool to 60℃, filter the material out with nitrogen pressure and pass it into a filter, leaving the catalyst in the filter, and finely filter the filtrate to obtain a colorless, transparent, viscous liquid as the product.

[0032] The samples were analyzed for iodine value, acid value, color, composition, including monoacid, diacid and triacid, etc. The experimental results are shown in Tables 1 and 2.

[0033] Example 2: Catalyst application test of hydrogenated dimer acid without solvent

[0034] 200g of common dimer acid and 10g of Pd / C catalyst (containing 5wt% palladium and 45wt% water) were added to a 2L hydrogenation autoclave in multiple groups. After vacuuming and replacing the air with nitrogen, hydrogen with a purity greater than 90v% was added. The reaction pressure was maintained at 1.5-2.5MPa, and the reaction was stirred at 160-180℃ for 3h. Stirring was stopped and the temperature was cooled to 60℃. The material was filtered out by nitrogen pressure and entered the filter. The catalyst remained in the filter. The filtrate was finely filtered to obtain a colorless, transparent, viscous liquid, which was the product. Samples were taken for analysis of iodine value, acid value, chromaticity, composition, including monoacid, diacid and triacid.

[0035] The filtered hydrogenation catalyst continued to be used without adding new catalyst. It was used 12 times in total. The test results are shown in Table 3.

[0036] Example 3: Scale-up test of hydrogenated dimer acid without solvent addition

[0037] Add 25000g of common dimer acid and 1250g of Pd / C catalyst (containing 5wt% palladium and 45wt% water) into a 30L hydrogenation autoclave in multiple groups, evacuate and replace the air with nitrogen, then fill with hydrogen with a purity greater than 90v%, maintain the reaction pressure at 2.0-2.5MPa, stir and react at 160-180℃ for 3h, stop stirring, and cool to 60℃. Use nitrogen to filter out the material into the filter, and the catalyst remains in the filter. The filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product hydrogenated dimer acid.

[0038] The samples were analyzed for iodine value, acid value, color, composition, including monoacid, diacid and triacid, etc. The test results are shown in Table 4.

[0039] Example 4: Comparative test of adding solvent to hydrogenate dimer acid

[0040] Add 200g of common dimer acid, 200g of solvent cyclohexane and 10g of Pd / C catalyst (containing 5wt% palladium and 45wt% water) into a 2L hydrogenation autoclave in multiple groups, evacuate and replace the air with nitrogen, then fill with hydrogen with a purity greater than 90v%, maintain the reaction pressure at 2.0-2.5MPa, stir and react at 160-180℃ for 3h, stop stirring, and cool to 60℃. Use nitrogen to filter out the material into the filter, and the catalyst remains in the filter. The filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product.

[0041] The samples were analyzed for iodine value, acid value, color, composition, including monoacid, diacid and triacid, etc. The test results are shown in Table 5.

[0042] Comparative Example

[0043] Patent document CN102618393A Example 2: 600g of 200# solvent oil and 10g of Pd / C catalyst (wet, dry weight 6g) suspension are placed in a 2L hydrogenation autoclave, and then 900g of dimer acid is added, and vacuum, nitrogen replacement, and hydrogen replacement are performed respectively. Then, hydrogen with a purity greater than 99.9% is filled, the hydrogen pressure in the autoclave is adjusted, the reaction mixture is controlled at 215-235°C, and the reaction pressure is maintained at 4.0-5.0MPa and stirred for about 4.5h. Fresh hydrogen is continuously added during the process until the hydrogen is completely absorbed, and the iodine value is sampled and analyzed. When it is less than 10 (g / 100g), it indicates that the hydrogenation is basically completed, and stirring is stopped, and the temperature is cooled to 130°C. The material was filtered out by nitrogen pressure, and the catalyst remained in the filter. The filtrate was finely filtered, and the obtained reaction mixture was subjected to a scraper film distillation at 100°C and 1500Pa to remove most of the solvent. Then, the residual solvent was removed in a short-range molecular distiller at a vacuum of 220Pa and a temperature of 180°C to obtain a colorless, transparent, viscous liquid as the product. The iodine value of the product was analyzed to be 6.5I2 / 100g, and the color (Pt-Co) was 160.

[0044] Table 1 Experimental results of the effect of reaction temperature on hydrogenation of dimer acid without solvent (reaction pressure 1.5-2.5MPa)

[0045]

[0046] As can be seen from Table 1, the method without adding solvent was examined at a reaction pressure of 1.5-2.5 MPa and a reaction temperature of 80, 100, 120, 140, 150, 160, 180°C, 200°C, and 220°C.

[0047] The test shows that the hydrogenation reaction starts at 80℃, and the hydrogenation reaction proceeds faster at 100℃ and 150℃. When the reaction temperature exceeds 180℃, the color of hydrogenated dimer acid is adversely affected. When the reaction temperature is lower than 120℃, the hydrogenation reaction speed is slow and the hydrogenation effect is not good enough; therefore, the best reaction temperature is 140-180℃.

[0048] Table 2 Test results of the effect of reaction pressure on hydrogenation of dimer acid without solvent (reaction temperature 150-180°C)

[0049]

[0050]

[0051] As shown in Table 2, the reaction temperature is 150-180℃, and the reaction pressure is 1.0, 1.5, 2.0, 2.5, 3.0, 4.0MPa. The results show that the higher the reaction pressure, the faster the hydrogenation reaction speed and the better the hydrogenation effect; the lower the reaction pressure, the slower the hydrogenation reaction speed and the worse the hydrogenation effect; the reaction pressure is higher than 3.5MPa, and further increasing the pressure has no obvious effect on the hydrogenation effect. The best reaction pressure is 1.5-2.5MPa.

[0052] From the perspective of economic efficiency and safety of industrial production, low reaction pressure is beneficial.

[0053] Research shows that:

[0054] 1. The acid value and composition of hydrogenated dimer acid change little, which means that the two main reaction functional groups of hydrogenated dimer acid, carboxyl, still exist. Hydrogenated dimer acid has all the properties of ordinary dimer acid related to carboxyl. Hydrogenated dimer acid can also be used in the fields where ordinary dimer acid is used. Due to the special structure of hydrogenated dimer acid, most polymer materials produced by it have good flexibility, waterproofness, biocompatibility, degradability and other excellent properties.

[0055] 2. The iodine value and chromaticity of hydrogenated dimer acid change significantly. The iodine value can be reduced by about 95%, indicating that most of the double bonds in the dimer acid molecules are saturated with hydrogen, thereby significantly improving its thermal stability and light stability. The chromaticity can be increased from 7# to 3#-5#, which is very beneficial for related materials with certain color requirements, and thus provides more possibilities for the preparation of new multifunctional polymer materials.

[0056] Table 3 Test results of catalyst application for hydrogenation of dimer acid without solvent (1.5-2.5MPa / 160-180℃)

[0057]

[0058] It can be seen from Table 3 that without adding new agent, the catalyst was used continuously for 12 times. As the number of applications increased, the iodine value tended to increase. Overall, the catalyst activity was relatively stable and the hydrogenation effect was good.

[0059] Table 4 Scale-up test results of dimer acid hydrogenation without solvent (reaction pressure 2.0-2.5MPa)

[0060]

[0061] As can be seen from Table 4, the feed amount of raw materials per reactor increased from 200g to 25000g, an increase of 125 times. Under basically the same process conditions, the scale-up results reached and exceeded the small-scale test results.

[0062] Table 5 Test results of adding solvent to dimer acid hydrogenation (reaction temperature 160-180°C)

[0063]

[0064]

[0065] It can be seen from Table 5 that adding solvent can also achieve good hydrogenation effect. After adding solvent, the viscosity of the material can be significantly reduced, which is beneficial for the transportation and filtration of the material, but the total material mass increases, the equipment investment and energy consumption increase, and the operation is complicated.

[0066] In summary, both the addition of solvent and the absence of solvent can produce hydrogenated dimer acid of good quality. Hydrogenated dimer acid without solvent has the characteristics of simplified process flow, mild operating conditions, low investment and energy consumption, and good quality of hydrogenated products, and has good industrial application prospects.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a solvent-free hydrogenated dimer acid, characterized in that: Ordinary dimer acid is used as raw material without adding any solvent, and catalytic hydrogenation is performed for 2-6 hours using a catalyst at a reaction temperature of 160-180°C and a reaction pressure of 1.0-2.5MPa, followed by post-treatment to obtain hydrogenated dimer acid; The common dimer acid has a monoacid content of 1-4wt%, a diacid content of 77-83wt%, and the balance is triacid; The catalyst is a palladium-carbon catalyst, containing 1-10wt% palladium and 40-60wt% water; The amount of the palladium carbon catalyst used is 2.5-5wt% of the amount of ordinary dimer acid used.

2. The method for preparing a solvent-free hydrogenated dimer acid according to claim 1, characterized in that: The hydrogen used in the catalytic hydrogenation does not contain any elements harmful to the palladium-carbon catalyst, including but not limited to sulfur and chlorine.

3. The method for preparing a solvent-free hydrogenated dimer acid according to claim 2, characterized in that: The purity of the hydrogen is ≥ 90v%, and its source is selected from any one or more of hydrogen produced from natural gas, hydrogen produced from coal, and hydrogen produced from water electrolysis.

4. The method for preparing a solvent-free hydrogenated dimer acid according to claim 1, characterized in that: The catalyst is separated by centrifugation, plate filtration or membrane filtration.

5. The method for preparing a solvent-free hydrogenated dimer acid according to claim 4, characterized in that: The catalyst is filtered using a metal membrane filter.

6. The method for preparing a solvent-free hydrogenated dimer acid according to claim 1, characterized in that: The reactor used for catalytic hydrogenation is a batch stirred reactor or a continuous fixed bed reactor.

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