A method for preparing hydrogenated high-purity dimer acid

Abstract

The invention discloses a method for preparing hydrogenated high-purity dimer acid, which uses high-purity dimer acid as a raw material, does not add any solvent, performs catalytic hydrogenation at a reaction temperature of 100-250° C. and a reaction pressure of 0.5-5.0 MPa, separates and removes the catalyst, and recycles the separated catalyst to obtain hydrogenated high-purity dimer acid with light color and low iodine value. Compared with hydrogenation by adding solvent, the method has the characteristics of short process flow, low investment and energy consumption, mild operating conditions, good product quality, etc., and has high social use value and 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 hydrogenated high-purity dimer acid. Background Art

[0002] Hydrogenated high-purity dimer acid is an aliphatic saturated high-purity dimer acid composed of 32 or more 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] 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 remainder is about 18wt% of trimer acid. High-purity dimer acid refers to a dimer acid that uses advanced separation technology to remove impurities such as monoacid, trimer and polymeric acid in conventional dimer acid, so that the content of dimer in the dimer acid reaches more than 95wt%. The high-purity dimer acid, wherein the content of dimer acid is>95wt%, or even more than 98wt% (for example, the high-purity dimer acid produced by the applicant Anhui Hongtai New Materials Co., Ltd. has a content of more than 98%, and the brand is HY-13). The production method of high-purity dimer acid refers to patent CN112125796A, a method for preparing high-purity dimer acid.

[0005] Compared with unhydrogenated high-purity dimer acid, the resins, inks, hot melts, resin films, etc. prepared with high-purity hydrogenated dimer acid have significantly improved and enhanced thermal stability, light stability, chemical stability, color and physical and mechanical properties, and are more widely used.

[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 hot spot in new material research. In particular, they play an increasingly important role in rocket propellants, advanced lubricants, drug sustained-release materials, bioremediation materials, polymer membrane materials and other aspects.

[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] CN201811505003.5 discloses a continuous synthesis method of hydrogenated dimer acid, comprising the following steps: (1) dispensing the catalyst into N-stage 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 product 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, and stirring until the iodine value is ≤8gI2 / 100g, thereby preparing 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 or hydrogenates high-purity dimer acid in the presence of a solvent and a catalyst.

[0013] The method is characterized in that cyclohexane and other solvents are used to prepare a 40%-80% solution with raw material dimer acid, and catalytic hydrogenation is carried out at 190-240°C, 3.0-6.0MPa, and hydrogen purity>99.9%. The hydrogenation product must be subjected to two-stage distillation at normal pressure and vacuum to remove the solvent in order to obtain hydrogenated dimer acid.

[0014] 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

[0015] In order to solve the problems mentioned in the above background technology, a solvent-free method for hydrogenating high-purity dimer acid was developed. The method was studied in 1L, 2L and 30L high-pressure hydrogenation reactors. The catalyst, process conditions, different high-purity dimer acid raw materials, catalyst separation and filtration methods and their effects were studied and tested in detail, and good results were achieved.

[0016] In order to achieve the above object, the present invention adopts the following technical solutions:

[0017] A method for preparing hydrogenated high-purity dimer acid, which uses high-purity dimer acid as a raw material, does not add any solvent, adds a catalyst for catalytic hydrogenation at a reaction temperature of 100-250°C and a reaction pressure of 0.5-5.0MPa, separates and removes the catalyst, and recycles the separated catalyst to obtain a hydrogenated high-purity dimer acid product with light color, low iodine value and high added value.

[0018] Preferably, the raw material high-purity dimer acid is one or more of tall oil high-purity dimer acid, cottonseed oil high-purity dimer acid, soybean oil high-purity dimer acid, corn oil high-purity dimer acid, sunflower seed high-purity dimer acid, rapeseed oil high-purity dimer acid, rice bran oil high-purity dimer acid, palm oil high-purity dimer acid, etc.

[0019] Preferably, the hydrogen does not contain sulfur, chlorine or other elements harmful to the activity of the catalyst, and the hydrogen purity is preferably ≧90v%, more preferably ≧95v%. The hydrogen source can be obtained by common methods such as hydrogen production from natural gas, coal, and hydrogen production from water electrolysis.

[0020] Preferably, the active components of the catalyst are composed of platinum, palladium, ruthenium, nickel, copper, etc., and the content of the active components is 0.1wt%-15wt% of the catalyst, preferably 1.0wt%-10wt%. The amount of the catalyst is 0.5wt%-20wt% of the raw material, preferably 1.0wt%-10wt%. The catalyst filtered out of the hydrogenation reaction can be recycled, and the metal components in the catalyst discharged can be recycled.

[0021] Preferably, the hydrogenation reactor used in the catalytic hydrogenation is a batch-type stirred reactor or a continuous fixed-bed hydrogenation reactor.

[0022] Preferably, the catalytic hydrogenation process conditions are: reaction temperature 100-250°C, preferably 120-220°C, more preferably 140-180°C; reaction pressure 0.5-5.0MPa, preferably 1.0-3.5MPa, more preferably 1.5-2.5MPa; hydrogenation reaction time 1-10h, preferably 2-6, more preferably 3-4h.

[0023] Preferably, the hydrogenated high-purity dimer acid product is separated and the catalyst is removed by conventional methods, such as centrifugal separation, plate filtration, membrane filtration, etc. Since the viscosity of hydrogenated dimer acid at room temperature and pressure is very high, 5000-7000mpa.s / 25°C, if the catalyst particles are 5-50 microns, or even less than 0.5 microns, it is preferably carried out using a metal membrane filter at a temperature higher than room temperature and pressure. The filtration can be a single-stage filtration or a two-stage filtration, i.e., a coarse filtration + a fine filtration.

[0024] The specific steps are:

[0025] Using intermittent stirred tank reactor:

[0026] Add high-purity dimer acid and catalyst as raw materials into a high-pressure hydrogenation kettle, replace the air in the kettle with nitrogen, repeat this process 3 times, or remove the air in the kettle by vacuuming, and detect that the oxygen content in the hydrogenation kettle is <0.2V% for safety, then replace the nitrogen with hydrogen for more than 2 times, add hydrogen to the hydrogenation kettle, and slowly increase the temperature at a rate of 2-5°C / min, and start stirring at a rate of 50-800rpm.

[0027] As the reaction temperature rises, the hydrogenation reaction speed changes from slow to fast, and the hydrogen consumption gradually increases. It is necessary to evenly and stably add hydrogen to the reactor to keep the temperature and pressure of the reactor in an appropriate range. For example, the preferred reaction temperature is 140-180°C; the reaction pressure is 1.5-2.5MPa; and the hydrogenation reaction time is 2-4h. When the hydrogenation reaction is completed, the hydrogen consumption stops, and it continues to be stable for about 1h, and the hydrogenation reaction is completed.

[0028] After the hydrogenation reaction is completed, the reaction system begins to cool down and reduce pressure, the temperature drops to <80°C, and the pressure drops to <1.0MPa, and the hydrogenation product is filtered. The filtering method can be carried out by a known method. The filtering can be a single-stage filtering or a two-stage filtering, that is, a coarse filtration + fine filtration method. Both can achieve good results.

[0029] The liquid obtained by filtration is the hydrogenated high-purity dimer acid, and the filtered solid is the catalyst, which can be recycled and reused. The catalyst after use can be recovered and utilized.

[0030] Using a continuous fixed bed hydrogenation reactor:

[0031] The hydrogenation process is greatly simplified. First, no solvent is needed, thus eliminating the solvent separation process. Second, the catalyst separation step can be omitted, thereby further simplifying the production process. Fixed bed catalytic hydrogenation is a classic and mature process technology, which will not be described in detail here. Please refer to patent CN201811505003.5.

[0032] First, install the catalyst in the reactor, replace the air with nitrogen, and purge the system until the oxygen content in the system is <0.2v%, and the purge is completed.

[0033] The second step is catalyst activation treatment. After the purge is completed, the system is kept filled with nitrogen at a pressure of 0.5-1.0MPa, the temperature is gradually increased, the nitrogen is replaced by hydrogen, and the catalyst is activated at 100-400°C;

[0034] The third step is catalytic hydrogenation. After the catalyst is activated, the temperature is lowered to about 100°C, and the reaction temperature and pressure are adjusted to carry out the catalytic hydrogenation reaction of high-purity dimer acid.

[0035] The hydrogenation process conditions are as follows: reaction temperature 100-250°C, preferably 120-220°C, more preferably 140-180°C; reaction pressure 0.5-5.0MPa, preferably 1.0-3.5MPa, more preferably 1.5-2.5MPa; feed space velocity 0.5-5.0h-1, preferably 1.0-3.0h-1; the reaction product is cooled, gas-liquid separated, and gas and light components are removed to obtain hydrogenated high-purity dimer acid.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. During the hydrogenation process of the high-purity dimer acid raw material, no solvent is added, which simplifies the process flow, reduces investment and energy consumption, and obtains high-quality hydrogenated high-purity dimer acid products.

[0038] 2. The high-purity dimer acid is hydrogenated without solvent, which 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. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0041] At present, the research on hydrogenated high-purity dimer acid in China mainly adopts solvent method. The inventors have conducted in-depth and detailed research on the method of hydrogenating high-purity dimer acid and developed a method for preparing hydrogenated high-purity dimer acid. The method was tested in 1L, 2L and 30L high-pressure hydrogenation reactors respectively. A detailed comparison was made between the solvent method and the method without solvent. The study showed that the experimental method and process conditions have a great influence on the effect of dimer acid hydrogenation, and it is very important to choose appropriate process conditions.

[0042] In the examples, different batches of high-purity dimer acid products produced by Anhui Hongtai New Materials Co., Ltd. were used as raw materials for the test, with a content of more than 98% and a brand name of HY-13. The properties of raw materials 1, 2, and 3 used in the hydrogenation test and the hydrogenated high-purity dimer acid are listed in Tables 1 and 2, respectively.

[0043] Example 1

[0044] Test of hydrogenation of high purity dimer acid without solvent:

[0045] Raw material 1, add 200g high-purity dimer acid and 10g Pd / C catalyst (wetting agent, water content 45wt%) into 1L hydrogenation autoclave, evacuate and replace air with nitrogen, then fill with hydrogen with purity greater than 90v%, control reaction temperature 80-180℃, maintain reaction pressure 1.0-2.5MPa, stir reaction at 160-180℃ for about 3h, stop stirring, cool to 60℃. Use nitrogen to filter out the material into the filter, the catalyst remains in the filter, and the filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product of hydrogenated high-purity dimer acid. Take samples and analyze iodine value, acid value, chromaticity, viscosity, composition, including monoacid, diacid and triacid.

[0046] Example 2

[0047] Test of hydrogenation of high purity dimer acid without solvent:

[0048] Raw material 1, add 200g high-purity dimer acid and 10g Pd / C catalyst (wetting agent, water content 45wt%) into a 2L hydrogenation autoclave, evacuate or replace air with nitrogen, then fill with hydrogen with a purity greater than 90v%, control the reaction temperature to 80-180℃, maintain the reaction pressure at 1.0-2.5MPa, stir and react at 160-180℃ for about 3h, stop stirring, and cool to 60℃. Use nitrogen to filter out the material into the filter, the catalyst remains in the filter, and the filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product of hydrogenated high-purity dimer acid. Take samples and analyze the iodine value, acid value, chromaticity, viscosity, composition, including monoacid, diacid and triacid.

[0049] Example 3

[0050] Comparative test of adding solvent to hydrogenate high purity dimer acid:

[0051] Raw material 1, add 200g high-purity dimer acid, 200g solvent cyclohexane and 10g Pd / C catalyst (wetting agent, water content 45wt%) into a 2L hydrogenation autoclave, evacuate and replace air with nitrogen, then fill with hydrogen with a purity greater than 90v%, control the reaction temperature at 100-180℃, maintain the reaction pressure at 1.5-3.5MPa, stir the reaction at 160-180℃ for about 3h, stop stirring, and cool to 60℃. Use nitrogen to filter out the material into the filter, the catalyst remains in the filter, and the filtrate is finely filtered to obtain a colorless, transparent, viscous liquid as the product. Take samples and analyze the iodine value, acid value, chromaticity, viscosity, composition, including monoacid, diacid and triacid.

[0052] Example 4

[0053] Test of hydrogenation of high purity dimer acid without solvent:

[0054] Raw material 2, add 200g high-purity dimer acid and 5g Pd / C catalyst (wetting agent, water content 45wt%) into 1L hydrogenation autoclave, evacuate and replace air with nitrogen, then fill with hydrogen with purity greater than 90v%, control reaction temperature 80-180℃, maintain reaction pressure 1.0-2.5MPa, stir reaction at 160-180℃ for about 3h, stop stirring, cool to 60℃. Use nitrogen to filter out the material into the filter, the catalyst remains in the filter, and the filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product of hydrogenated high-purity dimer acid. Take samples for analysis of iodine value, acid value, chromaticity, viscosity, composition, including monoacid, diacid and triacid.

[0055] The test results of Examples 1-4 are shown in Table 1.

[0056] Table 1 High-purity dimer acid hydrogenation test results (reaction pressure 1.5-2.5MPa, temperature 150-180°C)

[0057]

[0058]

[0059] Color analysis method:

[0060] 1. Colorimetric method, such as 4#, etc.

[0061] 2. Spectrophotometry: the instrument is imported LICO620, such as G0.2, etc.

[0062] Example 5: Scale-up test

[0063] Raw material 3, add 25000g dimer acid and 1250g Pd / C catalyst (wetting agent, water content 45wt%) into a 30L hydrogenation autoclave, evacuate and replace air with nitrogen, then fill with hydrogen with purity greater than 90v%, control the reaction temperature to 80-180℃, maintain the reaction pressure at 1.5-2.5MPa, stir the reaction at 150-165℃ for about 3h, stop stirring, and cool to 60℃. Use nitrogen to filter out the material into the filter, the catalyst remains in the filter, and the filtrate is finely filtered to obtain a colorless, transparent, viscous liquid, which is the product of hydrogenated high-purity dimer acid. Sampling and analysis of iodine value, acid value, chromaticity, viscosity, composition, including monoacid, diacid and triacid, etc.

[0064] The results of the scale-up test are shown in Table 2.

[0065] Table 2 High-purity dimer acid hydrogenation scale-up test results (reaction pressure 1.5-2.5MPa, temperature 150-165°C)

[0066]

[0067] It can be seen from Table 1 and Table 2 that good results can be obtained by using the method of adding solvent or not adding solvent under the conditions of reaction pressure of 1.5-2.5 MPa and reaction temperature of 150-180°C.

[0068] 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 better reaction temperature is 150-180℃.

[0069] As shown in Table 2, the feed amount of raw materials per reactor increased from 200g to 25000g, which is 125 times larger. Under the same reaction pressure and reaction temperature about 15℃ lower, the enlarged result reached and was better than the small test result. The iodine value dropped from 134 to 2.2I2 / 100g, corresponding to a double bond hydrogenation saturation rate of 98.5%. The color increased from G3.4 to G0.0. The high-purity dimer acid before hydrogenation was light yellow, and the high-purity dimer acid after hydrogenation was colorless and transparent.

[0070] Compared with the raw material, the acid value and composition of hydrogenated high-purity dimer acid change very little, indicating that the two original main reaction functional groups of hydrogenated high-purity dimer acid, carboxyl, still exist. All the properties of high-purity dimer acid related to carboxyl, hydrogenated high-purity dimer acid have. Hydrogenated high-purity dimer acid can also be used in the fields where high-purity dimer acid is used. U.S. Patent US62 / 190304 and Chinese Patent CN107725426A report that transparent polyamide prepared with fully hydrogenated dimer acid has high heat resistance, low-temperature flexibility, good adhesion, and the film prepared has ultra-high tensile modulus and good UV resistance.

[0071] The iodine value and chromaticity of hydrogenated high-purity 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 improved from light yellow to colorless and transparent, which is very beneficial for related materials with certain color requirements, and thus provides more possibilities for the preparation of new multifunctional polymer materials.

[0072] Due to the special structure of high-purity hydrogenated dimer acid, most of the polymer materials produced by it have excellent properties such as good flexibility, waterproofness, biocompatibility, and degradability.

[0073] In summary: Although good hydrogenation effects can be obtained with or without solvent addition, the total material mass increases after solvent addition, and subsequent processes need to remove the solvent, which significantly increases equipment investment and energy consumption, and complicates the operation.

[0074] The high-purity dimer acid is hydrogenated without solvent, which has the characteristics of simplified process flow, mild operating conditions, low investment and energy consumption, good quality of hydrogenated products, etc., and has good industrial application prospects.

[0075] 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 hydrogenated high-purity dimer acid, characterized in that: Using high-purity dimer acid as raw material, without adding any solvent, under the conditions of reaction temperature of 100-180°C, reaction pressure of 1.0-3.5MPa, hydrogenation reaction time of 1-10h, adding catalyst for catalytic hydrogenation, separating and removing the catalyst, and recycling the separated catalyst to obtain a hydrogenated high-purity dimer acid product with light color, low iodine value and high added value; The catalyst, whose active components include platinum, palladium, ruthenium, nickel and copper, has an active component content of 0.1wt%-15wt% of the catalyst; The amount of catalyst used is 0.5wt%-5wt% of the raw material; The diacid content in the high-purity dimer acid raw material is 98.9-99.5wt%.

2. The method for preparing a hydrogenated high-purity dimer acid according to claim 1, characterized in that: The dosage of the catalyst is 2.5wt%-5wt% of the raw material. The catalyst filtered out from the hydrogenation reaction is recycled, and the metal components in the catalyst discharged can be recovered.

3. The method for preparing a hydrogenated high-purity dimer acid according to claim 1, characterized in that: The hydrogen used in the catalytic hydrogenation is required to be free of elements harmful to the activity of the catalyst, including but not limited to sulfur and chlorine.

4. The method for preparing a hydrogenated high-purity dimer acid according to claim 1, characterized in that: The catalyst in the hydrogenation product is filtered and removed by any one of centrifugal separation, plate filtration and membrane filtration.

5. The method for preparing a hydrogenated high-purity dimer acid according to claim 1, characterized in that: The hydrogenation reactor used in the catalytic hydrogenation is a batch-type stirred reactor or a continuous fixed-bed hydrogenation reactor.

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