A method for preparing long carbon chain dicarboxylic acid

Abstract

The invention provides a method for preparing a long-chain dicarboxylic acid, wherein a dihydroxy macrocyclic olefin and a hydrogenation catalyst are heated in a hydrogen-containing gas atmosphere until the reaction is complete to obtain a hydrogenated product; the hydrogenated product, an oxidation catalyst, an oxidation aid, and an oxidant are mixed until the reaction is complete to obtain the desired long-chain dicarboxylic acid. The invention has the following beneficial effects: The method for preparing a long-chain dicarboxylic acid according to the invention adopts a series hydrogenation-oxidation process to achieve the preparation of the long-chain dicarboxylic acid, and the process is green and environmentally friendly, the reaction process conditions are mild, the reaction risk is safe and controllable, and a large amount of nitrogen oxides NO in the nitric acid oxidation process is avoided. x The emergence of this is in line with the general trend of chemical industry development under the “dual carbon” policy.

Description

Technical Field

[0001] The invention belongs to the field of fine chemical synthesis, and in particular relates to a method for preparing a long carbon chain dicarboxylic acid. Background Art

[0002] Long-chain dicarboxylic acids are straight-chain dicarboxylic acids with more than 8 carbon atoms in the carbon chain, and are an important class of fine chemical products. Among them, dodecanedioic acid is the largest long-chain dicarboxylic acid in the market. Using dodecanedioic acid as an intermediate, different long-chain special nylons can be synthesized according to different amines, such as nylon 612, nylon 1012, nylon 1212 and nylon 12T. Long-chain nylon has significant specificity compared to general-purpose nylon 6 and nylon 66. It has a low amide group concentration and a long carbon chain. Therefore, in addition to most of the versatility of ordinary nylon, it also has excellent wear resistance, low moisture absorption rate, excellent hydrolysis resistance, excellent impact strength at low temperatures, dimensional stability, weather resistance, chemical resistance, excellent barrier properties, stress cracking resistance, fatigue resistance, and good NVH performance. Therefore, it is widely used in many fields such as automobile manufacturing, submarine cables, and industrial brushes. In addition, a variety of high-grade fragrances can be prepared using dodecanedioic acid as an intermediate, such as cyclopentadecanolide, musk ketone, 5-cyclohexadecenone, cyclopentadecanone, 12-methyl-14-carbonylbicyclo[9,3,1]pentadecane, etc.

[0003] The synthesis process of dodecanedioic acid includes the following:

[0004] 1. Biological fermentation of normal alkanes

[0005] The biological fermentation method mainly uses C11-C18 normal alkanes as raw materials, and converts the monoalkanes into a variety of long-chain dibasic acid mixtures through Candida fermentation, including sebacic acid, undecanoic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, hexadecanedioic acid and octadecanedioic acid. Then, through multiple steps such as dissolution, decolorization, acidification, crystallization, filtration, and drying, a variety of long-chain dibasic acid crystalline products are obtained. The reaction conditions of the biological fermentation method are relatively mild, but the monoacid purity of the produced dodecanedioic acid is only 97-98.5%, the color is poor, the crystal size is uneven, and the residual bacterial protein is difficult to remove. The product quality is lower than that of the chemical synthesis method (monoacid purity is more than 99.0%). At the same time, the fermentation method requires a large amount of sodium sulfate as a by-product, the overall equipment investment is large, the wastewater volume is large, the production cost is high, and the environmental problems are prominent.

[0006] 2. Cyclohexanone Oxidative Ring Opening-Dimerization Process

[0007] US2601223 discloses a method for preparing dodecanedioic acid by ring-opening-dimerization of cyclohexanone via hydrogen peroxide oxidation, specifically using methanol as solvent, Fe 2+Salt is used as a catalyst, hydrogen peroxide oxidizes cyclohexanone to make it open-ring polymerized and then esterified to obtain dodecanedioic acid, which is then saponified and acidified with NaOH to obtain dodecanedioic acid. US3917687 and US3907883 removed the methanol solvent and used Fe 2+ Salt is used as a catalyst to catalyze this reaction, and dodecanedioic acid can also be obtained. CN104610040A discloses that no Fe is added 2+ Salt catalyst, under light irradiation, ring-opening polymerization of hydrogen peroxide and cyclohexanone. According to the currently published patent reports, the yield of dodecanedioic acid obtained by the above-mentioned process is low, only 40-60%. At the same time, the catalyst Fe 2+ The amount of salt and hydrogen peroxide used is large, 30-50 times and 8-10 times the molar mass of cyclohexanone, respectively. On the one hand, the iron content is difficult to completely remove through subsequent purification, which seriously affects the molecular weight control and polymer product performance of the subsequent polymerization reaction. On the other hand, excessive hydrogen peroxide post-treatment is very likely to cause decomposition at high temperatures, posing a major safety hazard. Therefore, this process does not have technical and cost advantages for industrial production.

[0008] 3. Macrocyclic alcohol ketone oxidation ring-opening reaction process

[0009] CN101970392A discloses that cyclododecanone / alcohol mixture with 30-70% cyclododecanone content is used as raw material, and 12-carbon diacid is obtained by oxidation with excessive nitric acid under the action of copper and vanadium catalysts, with a yield of 88%. CN108017533A reports that a reaction crystallization method is used to control the particle size distribution of the product 12-carbon diacid to carry out oxidation reaction of cyclododecanone and excess nitric acid to prepare 12-carbon diacid. The reaction uses 65-90wt% concentrated nitric acid as an oxidant, and its nitric acid / raw material molar ratio is as high as (10-15): 1. This type of process uses a process similar to adipic acid, but due to the difference in molecular structure, its nitric acid needs to be greatly excessive, and its nitric acid / raw material molar ratio is much higher than the adipic acid process, ① such a large amount of nitric acid will decompose and produce a large amount of nitrogen oxides NO x , which seriously pollutes the environment and is not in line with the country's "dual carbon" policy; ② The total reaction volume increases and the energy consumption of nitric acid concentration recycling increases greatly; ③ The nitric acid oxidation reaction releases a huge amount of heat, and a large amount of cooling water and safety interlock devices are required to remove the reaction heat in time, which poses a huge safety risk; ④ The reaction mechanism of nitric acid oxidation of cyclododecanone / alcohol is very complicated, and the main and side reactions are tandem reactions. A certain amount of nitrated dibasic acid by-products will be generated during the reaction, which cannot be completely removed by cooling and crystallization, seriously affecting the purity and quality of the product, and indirectly causing adverse effects on the performance of polymers with dodecanedioic acid as a monomer. Therefore, this process still has great technical defects.

[0010] 4. Macrocyclic olefin oxidative ring-opening process

[0011] EP0438143B1 discloses the use of RuO4-Ce(SO3CH3)4-methanesulfonic acid as a catalyst system to achieve heterogeneous oxidation of cyclododecene to prepare dodecanedioic acid. The lipophilic RuO4 oxidizes cyclododecene to dodecanedioic acid in the organic phase; the reduced ruthenium has limited solubility in the organic phase and is easily precipitated and extracted or dissolved in the aqueous phase by Ce 4+ The ion is oxidized to RuO4, which dissolves again in the organic phase and reacts with additional cyclododecene, completing the catalytic cycle. 3+ The ions are then electrolytically oxidized to convert Ce 3+ Ions converted to Ce 4+ ions. The loss of Ru can be minimized by using oil-water two-phase, the conversion rate of cyclododecene is 95%, and the selectivity of dodecanedioic acid is 87-88%. From the public information, this process requires a high content of Ce 4+ ions, the molar addition amount of which is 4 to 12 times that of cyclododecene, to ensure sufficient oxidation of Ru; and the catalytic cycle of Ce requires electrolytic oxidation, which further increases the equipment investment. In addition, the patent does not disclose the catalytic results of the catalytic system after multiple cycles. This is very critical to reducing the cost of precious metal catalysts.

[0012] US3461160A reported the preparation of dodecanediolacid by the oxidation reaction of cyclododecene and nitric acid catalyzed by OsO4 and V2O5. The reaction requires a mass ratio of Os to cyclododecene of 1.5-4.0 to obtain a yield of about 70%. The amount of catalyst used is huge, and the Os element is a precious metal element, the catalyst cost is extremely high, and the patent does not mention the issue of recycling the catalytic system, which is crucial for cost control of industrial production. In addition, the process involves the use of nitric acid as an oxidant, which is bound to produce a large amount of NO during the reaction. x Nitrogen oxides put enormous pressure on the environmental protection.

[0013] Compared with low-carbon dicarboxylic acids such as adipic acid, long-chain dicarboxylic acids with high carbon numbers, such as dodecanedioic acid, have the following technical difficulties in their synthesis process: ① Complexity of the reaction: The reaction mechanism of cyclohexanol nitric acid oxidation to produce adipic acid is to undergo a 6-oxime-6-nitrohexanoic acid intermediate process, which is directly converted into by-products glutaric acid and succinic acid. The main and side reactions are parallel reactions, and the addition of catalysts and temperature control are conducive to increasing the proportion of the main reaction. When the macrocyclic precursor of dodecanedioic acid is oxidized and opened, taking nitric acid as an oxidant, it is necessary to undergo the diacid molecule carboxyl α-nitro or nitroso diacid intermediate, and then the intermediate is further oxidized to a shorter carbon chain dicarboxylic acid through decarboxylation. The decarboxylation reaction is carried out in series, so its by-products will include C11, C10, C9, C8, C7, C6 and below dicarboxylic acids. How to avoid the occurrence of such cascade side reactions, so that the oxidation reaction only stays at C12 or a small amount to C11, and prevents it from further decarboxylation and oxidation to generate dibasic acids with lower carbon numbers, and develop new reaction processes are technical difficulties. ② Difficulty of separation of reactions: Compared with the two by-products of glutaric acid and succinic acid in the synthesis of adipic acid, the solubility curves of the main and by-products in water are significantly different, and high-purity adipic acid can be purified by cooling and crystallization; high-carbon number dodecanedioic acid will have C11, C10, C9, C8, C7, C6 and below dicarboxylic acids in the synthesis. These dibasic acids, especially long-chain dibasic acids, have very similar structures, and the solubility difference in solvents is not large, which makes crystallization separation very difficult. Therefore, it is necessary to develop a green oxidation process that is not based on nitric acid to achieve the preparation of long-chain dicarboxylic acids represented by dodecanedioic acid.

[0014] In order to overcome the limitations of the existing technology and the technical difficulties in the preparation of the above-mentioned long-chain dicarboxylic acids, it is necessary to focus on solving the following problems: ① Develop a green oxidation process, use a green oxygen source as a catalyst, realize the preparation and production of long-chain dicarboxylic acids, and avoid further cascade decarboxylation of the products to form low-carbon dicarboxylic acid by-products through the control of reaction process conditions; ② Reduce the difficulty of separating the reaction products, especially reduce the generation of low-carbon dicarboxylic acids and other high-boiling point by-products, and improve the reaction selectivity; ③ Reduce the reaction cost, including the catalyst cost and the cost of using other raw materials; ④ Improve production efficiency and maximize the technical competitiveness. Invention content

[0015] In view of this, the present invention aims to propose a method for preparing a long-chain dicarboxylic acid to avoid the emission of nitrogen oxides, reduce production costs, increase product yields, and reduce separation difficulty.

[0016] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0017] A method for preparing a long carbon chain dicarboxylic acid comprises the following steps:

[0018] (1) Hydrogenation process: using dihydroxy macrocyclic olefin as raw material, adding a hydrogenation catalyst, and carrying out a hydrogenation reaction in a hydrogen-containing gas atmosphere.

[0019] (2) Oxidation step: The product obtained from the hydrogenation reaction reacts with an oxidant under the action of an oxidation catalyst and an oxidation aid to prepare a long-chain dicarboxylic acid.

[0020] Furthermore, the raw material dihydroxy macrocyclic olefin in the hydrogenation step is a cyclic olefin containing 8-12 carbon atoms and having at least one carbon-carbon unsaturated double bond and the dihydroxyl group is in the ortho position.

[0021] Further, the dihydroxy macrocyclic olefin is one or more selected from 1,2-dihydroxy-5-cyclooctene, 1,2-dihydroxy-3-cyclooctene, 1,2-dihydroxy-5-cyclodecene, 1,2-dihydroxy-5,9-cyclododecene, preferably one or more of 1,2-dihydroxy-5-cyclooctene, 1,2-dihydroxy-5-cyclodecene or 1,2-dihydroxy-5,9-cyclododecene; particularly preferably 1,2-dihydroxy-5,9-cyclododecene.

[0022] Furthermore, the raw material dihydroxy macrocyclic olefin in the hydrogenation process can be obtained by hydration reaction of a macrocyclic epoxide containing 8-12 carbon atoms and at least one carbon-carbon unsaturated double bond under the action of a catalyst such as an acid, a base, a solid acid or an ion exchange resin; it can also be obtained as a by-product when a macrocyclic epoxide containing 8-12 carbon atoms and at least one carbon-carbon unsaturated double bond is prepared by any epoxidation reaction of a macrocyclic olefin containing 8-12 carbon atoms and at least one carbon-carbon unsaturated double bond; preferably, the macrocyclic olefin is obtained as a by-product of the epoxidation reaction to prepare an epoxy macrocyclic olefin.

[0023] Furthermore, the macrocyclic epoxide containing 8 to 12 carbon atoms and having at least one carbon-carbon unsaturated double bond is selected from one or more of 1,2-epoxy-5-cyclooctene, 1,2-epoxy-3-cyclooctene, 1,2-epoxy-5-cyclodecene, and 1,2-epoxy-5,9-cyclododecadiene, preferably one or more of 1,2-epoxy-5-cyclooctene, 1,2-epoxy-5-cyclodecene or 1,2-epoxy-5,9-cyclododecadiene, and particularly preferably Selected is 1,2-epoxy-5,9-cyclododecadiene; the macrocyclic olefin containing 8-12 carbon atoms and having at least one carbon-carbon unsaturated double bond is one or more selected from 1,5-cyclooctadiene, 1,3-cyclooctadiene, 1,5-cyclodecadiene, 1,5,9-cyclododecatriene, preferably one or more of 1,5-cyclooctadiene, 1,5-cyclodecadiene or 1,5,9-cyclododecatriene, and particularly preferably 1,5,9-cyclododecatriene. Preferably, 1,2-dihydroxy-5,9-cyclododecadiene is obtained by a hydration reaction between 1,2-epoxy-5,9-cyclododecadiene and water in the presence of a catalyst. Particularly preferably, 1,5,9-cyclododecatriene is subjected to an epoxidation reaction with any alkyl or aryl hydroperoxide or hydrogen peroxide of any concentration, and 1,2-dihydroxy-5,9-cyclododecadiene is obtained after separation as a by-product of 1,2-epoxy-5,9-cyclododecadiene.

[0024] Preferably, the dihydroxy macrocyclic olefin raw material of the hydrogenation process described in the present invention is obtained after separation as a by-product when a macrocyclic olefin is prepared into an epoxy macrocyclic olefin through an epoxidation reaction. On the one hand, this part of the by-product can be used to synthesize a long carbon chain dicarboxylic acid through a hydrogenation-oxidation tandem process, so as to fully develop the economic value of this part of the by-product, reduce the production cost, and maximize its economic benefit; on the other hand, it avoids the problem of low yield of preparing dodecanedioic acid by direct oxidation and ring opening of epoxy macrocyclic olefin (US3657335).

[0025] Furthermore, in the hydrogenation step, the main metal of the hydrogenation catalyst is one of nickel-based metals and platinum-group metals, preferably nickel-based metals; the hydrogenation catalyst carrier is one of alumina, activated carbon, silica, titanium dioxide, zirconium dioxide, molecular sieves, hydrotalcite, and diatomaceous earth, and the preferred carrier is one of silica or zirconium dioxide; silica is particularly preferred.

[0026] Furthermore, in the hydrogenation step, the amount of hydrogenation catalyst used is 0.01-5% of the mass of the dihydroxy macrocyclic olefin raw material, preferably 0.1-3%, and particularly preferably 0.5-2%.

[0027] Furthermore, the reaction temperature of the hydrogenation process is 50-250°C, preferably 100-230°C, and particularly preferably 150-220°C; the reaction pressure of the hydrogenation process is 0.1-5MPa, preferably 0.1-2MPa, and particularly preferably 0.1-1MPa. The reaction time of the hydrogenation process is 0.1-5h, preferably 0.5-3h, and particularly preferably 1-2h.

[0028] Furthermore, the products obtained in the hydrogenation process include macrocycloalkanones containing 8-12 carbon atoms and a hydroxyl group at the ortho position, macrocycloalkanones containing 8-12 carbon atoms and a carbonyl group at the ortho position, a small amount of macrocycloalkanes containing 8-12 carbon atoms and a dihydroxyl group at the ortho position, and a very small amount of high-boiling-point products.

[0029] Further, the macrocyclic alkanone containing 8-12 carbon atoms and having a hydroxyl group at the ortho position is selected from one or more of 1-hydroxycyclooctanone, 1-hydroxycyclodecanone, and 1-hydroxycyclododecanone, preferably one or more of 1-hydroxycyclooctanone and 1-hydroxycyclododecanone, and particularly preferably 1-hydroxycyclododecanone. The macrocyclic alkanone containing 8-12 carbon atoms and having a carbonyl group at the ortho position is selected from one or more of 1-carbonylcyclooctanone, 1-carbonylcyclodecanone, and 1-carbonylcyclododecanone, preferably one or more of 1-carbonylcyclooctanone and 1-carbonylcyclododecanone, and particularly preferably 1-carbonylcyclododecanone. The macrocyclic alkanes containing 8-12 carbon atoms and having a dihydroxyl group at the ortho position are selected from one or more of 1,2-dihydroxycyclooctane, 1,2-dihydroxycyclodecane, and 1,2-dihydroxycyclododecane, preferably one or more of 1,2-dihydroxycyclooctane and 1,2-dihydroxycyclododecane, and particularly preferably 1,2-dihydroxycyclododecane.

[0030] The present invention has found through research that among the products obtained in the hydrogenation process, the products containing unsaturated carbonyl groups, such as macrocycloalkanones with hydroxyl groups at the ortho position and macrocycloalkanones with carbonyl groups at the ortho position, can bring unexpected effects to the subsequent oxidation reaction to prepare long carbon chain dicarboxylic acids: the products containing unsaturated carbonyl groups are more advantageous than macrocycloalkanes with dihydroxyl groups at the ortho position for improving the selectivity of the products and reducing the occurrence of cascade side reactions. Therefore, the hydrogenation process adopted by the present invention is to control the catalyst and the reaction process so that the hydrogenation product of the raw material dihydroxy macrocycloolefin is mainly macrocycloalkanones or macrocycloalkanols containing unsaturated carbonyl groups, and the proportion of saturated dihydroxy macrocycloalkanes is reduced, which is obviously advantageous for the subsequent oxidation reaction.

[0031] Furthermore, the hydrogenation process of the present invention is carried out under a hydrogen-containing gas atmosphere, and the hydrogen-containing gas can be a pure hydrogen atmosphere or a hydrogen atmosphere containing a certain volume of nitrogen, wherein the ratio of hydrogen to nitrogen is 1:(0.1-10), preferably 1:(1-8), and particularly preferably 1:(3-5).

[0032] The catalyst has higher catalytic activity under pure hydrogen atmosphere. If the hydrogen flow rate is too high, on the one hand, it will cause the residence time of dihydroxy macrocyclic olefin raw material in the catalyst bed to be too short and cannot be fully converted. On the other hand, it will make the catalyst adsorb and dissociate hydrogen too strong, resulting in too fast hydrogenation reaction rate, accelerated reaction speed of dihydroxy macrocyclic alkane of saturated hydrogenation, decreased reaction selectivity, and unfavorable for the subsequent oxidation process. If the hydrogen flow rate is too low, the activity of the catalyst is relatively low, which has an adverse effect on reaction conversion rate and selectivity. Therefore, in a preferred embodiment of the present invention, the hydrogenation activity of the catalyst is controlled by adjusting the ratio of nitrogen to hydrogen to avoid the hydrogenolysis side reaction caused by the catalyst with higher activity, and then the raw material can be effectively suppressed after hydrogenation to generate macrocyclic alkanone or macrocyclic alkanol containing unsaturated carbonyl, and further excessive hydrogenation to obtain the occurrence of saturated dihydroxy macrocyclic alkane by-products.

[0033] Furthermore, the hydrogenation process can be carried out in the presence or absence of an external solvent, preferably without adding an external solvent. When carried out in the presence of an external solvent, it is preferably a solvent that is inert under the hydrogenation reaction conditions.

[0034] Furthermore, the reactor of the hydrogenation process is one of a loop reactor, a fixed bed reactor, a reactor, and a fluidized bed reactor, preferably a loop reactor or a fixed bed reactor, and particularly preferably a loop reactor.

[0035] Further, the crude product obtained in the hydrogenation step is subjected to purification measures, including distillation, chromatography, crystallization or a combination of measures. The distillation device used for purification includes an optionally equipped distillation column, a bubble column, a plate column or an evaporator, such as a thin film evaporator, a falling film evaporator, a forced circulation evaporator, a wiped film evaporator and a combination thereof.

[0036] Furthermore, in the oxidation process of the present invention, the oxidant is a hydrogen peroxide solution with a concentration of 10-75wt%, preferably 30-70wt%, and particularly preferably 50-60%. The molar ratio of the hydrogenation product to hydrogen peroxide is 1:(1-10), preferably 1:(1-5), and particularly preferably 1:(2-3).

[0037] Furthermore, the oxidation aid in the oxidation step has an ionization constant of 1×10 -6 ≤pKa≤5×10 -3The organic acid is selected from one or more of formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid, isovaleric acid, pivalic acid, chloroacetic acid, dichloroacetic acid, phthalic acid, and m-chlorobenzoic acid. The molar ratio of the amount of the oxidation aid added to the hydrogenation product is (1-20):1, preferably (2-10):1, and particularly preferably (3-5):1.

[0038] Furthermore, the catalyst in the oxidation process is an inorganic acid, a solid superacid, a strong acid resin, etc., and the catalyst is selected from sulfuric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, SO4 2- / M x O y Type solid superacid, Keggin structure (H 8-n X n M 12 O 40 ) one or more of heteropoly acid, macroporous strong acid styrene cation exchange resin, perfluorosulfonic acid resin, preferably sulfuric acid, p-toluenesulfonic acid, phosphotungstic acid, macroporous strong acid styrene cation exchange resin. The oxidation catalyst is added in an amount of 0.1-10wt% of the hydrogenation product, preferably in an amount of 0.5-6%, and particularly preferably in an amount of 1-3%.

[0039] Furthermore, the reaction temperature of the oxidation process is 50-120°C, preferably 60-100°C, and particularly preferably 60-80°C; the reaction time of the oxidation process is 0.5-5h, preferably 1-3h.

[0040] Furthermore, the reactor of the oxidation step is one of a loop reactor, a reactor, and a microchannel reactor, preferably a loop reactor or a microchannel reactor, and most preferably a loop reactor.

[0041] Furthermore, the crude product obtained in the oxidation step is subjected to purification measures, including distillation, chromatography, crystallization or a combination of measures.

[0042] In some embodiments of the present invention, during the oxidation process, the product, such as dodecanedioic acid, can be precipitated from the reaction system in a solid form in a timely manner due to its limited solubility in the aqueous reaction system, which can effectively reduce the occurrence of a series of side reactions of decarboxylation in the reaction system. In addition, the oxidation reaction system of the present invention has a smaller heat release, a milder reaction, and easier temperature control than the nitric acid oxidation system, so the selectivity of the reaction is higher than that of the nitric acid oxidation process.

[0043] In some embodiments of the present invention, the organic acid auxiliary used in the oxidation process undergoes an oxidation reaction with hydrogen peroxide to generate a peroxy organic acid intermediate, which then reacts with the raw material of the oxidation process to finally generate an organic acid auxiliary, which can be recycled and reused, and the recovery process is simple, requiring only simple distillation. In the production process of long-chain dicarboxylic acids, only a small amount of organic acid needs to be added after a period of time, further reducing production costs and equipment investment.

[0044] The long carbon chain dicarboxylic acid prepared by the present invention can be used to produce long carbon chain special nylons, such as nylon 612, nylon 1012, and nylon 1212; advanced synthetic fragrances, such as cyclopentadecanolide, musk ketone, 5-cyclohexadecenone, cyclopentadecanone, 12-methyl-14-carbonylbicyclo[9,3,1]pentadecane, etc.; high-end aviation lubricants, industrial cutting fluids, etc., which are applied to automobile manufacturing, submarine cables, industrial brushes, aviation manufacturing, and other fields.

[0045] Compared with the prior art, the method for preparing the long carbon chain dicarboxylic acid created by the present invention has the following advantages:

[0046] (1) The preparation method of the long carbon chain dicarboxylic acid created by the present invention adopts a series of hydrogenation-oxidation steps to achieve the preparation of the long carbon chain dicarboxylic acid. The process is green and environmentally friendly, the reaction process conditions are mild, the reaction risk is safe and controllable, and the large amount of nitrogen oxides NO in the nitric acid oxidation process is avoided. x The emergence of is in line with the general trend of chemical industry development under the "dual carbon" policy;

[0047] (2) The preparation method of the long-chain dicarboxylic acid created by the present invention regulates the hydrogenation activity of the catalyst by adjusting the hydrogen / nitrogen ratio in the hydrogenation process, and prepares a hydrogenation product mainly containing a macrocyclic alkanone or macrocyclic alkanol containing an unsaturated carbonyl group, which is beneficial to improve the selectivity of the long-chain dicarboxylic acid in the oxidation process. In addition, the reaction process used in the oxidation process is relatively mild, the reaction exotherm is small, and the temperature control is relatively easy. The product is precipitated in the aqueous system in a timely manner, which reduces the possibility of further decarboxylation to generate a dicarboxylic acid with a lower carbon number. Multiple control measures promote the oxidation reaction to have a higher reaction selectivity and yield. The yield of dodecanedioic acid can reach 90-93%, and its by-products are mainly undecanediol and sebacic acid, and the content of dicarboxylic acids with a lower carbon number is extremely low. In this way, the separation difficulty of the reaction is greatly reduced, and a dodecanedioic acid product with a purity of more than 99.0% can be obtained by cooling and crystallizing in an appropriate solvent. In addition, the preparation method of the present invention does not involve Fe 2+ ions or nitrogen-containing materials, etc., so its products will not contain Fe 2+ or nitrogen impurities, which has obvious advantages for the high quality requirements of long carbon chain dicarboxylic acids;

[0048] (3) The raw material dihydroxy macrocyclic olefin used in the preparation method of the long-chain dicarboxylic acid created by the present invention is preferably obtained by separation as a by-product when macrocyclic olefin is used to prepare epoxy macrocyclic olefin through epoxidation reaction. The existing by-products are used as raw materials to transform into long-chain dicarboxylic acids with high economic value, thereby improving atom economy, turning waste into treasure, reducing production costs, maximizing economic benefits, and enhancing the competitiveness of the entire long-chain product industry chain; the hydrogenation catalyst used in the hydrogenation process of the present invention can achieve long-term continuous operation, and the catalyst manufacturing cost and use cost are low, which also reduces the production cost of long-chain dicarboxylic acids; the oxidizing agent used in the oxidation process of the present invention can be recycled, and the recovery process is simple. In the production process of long-chain dicarboxylic acids, it is only necessary to supplement a small amount of organic acid after a period of time, which further reduces production costs and equipment investment;

[0049] (4) The method for preparing the long-chain dicarboxylic acid created by the present invention can realize continuous reaction, has obvious advantages in energy consumption required for the reaction, has high production efficiency, and is suitable for industrial production. In addition, the method described in the present invention is suitable for the preparation of long-chain dicarboxylic acids having 8-12 carbon atoms, and has strong applicability. DETAILED DESCRIPTION

[0050] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0051] The present invention will be described in detail below with reference to the embodiments.

[0052] In the following examples, the main and by-products of the hydrogenation process were analyzed by gas chromatography for each component in the reaction system, and the calibration and normalization method was used to quantify the components. On this basis, the conversion rate of the reactants, the selectivity and yield of the products were calculated. The main and by-products of the dicarboxylic acid in the oxidation process were subjected to esterification and derivatization treatment and then analyzed by gas chromatography, and the contents of the main and by-products were quantified by the calibration and normalization method.

[0053] The esterification derivatization method is as follows:

[0054] Weigh about 1.0g of solid sample into a flask, add 10g of anhydrous methanol, 10g of cyclohexane, and 2-3 drops of concentrated sulfuric acid, and heat at 60-65°C for esterification reaction, while using a water separator to remove water in time. After reacting for 1h, cool to room temperature and perform gas chromatography GC detection.

[0055] The gas chromatography analysis conditions are as follows:

[0056] Chromatographic column: Agilent DB-Wax (specifications: 30m×0.32mm×0.25mm); inlet temperature: 300℃; split ratio: 30:1; column flow rate: 1.5mL / min; column temperature: 100℃0.5min; heating program: 15℃ / min to 300℃, hold for 8min; detector temperature: 300℃, hydrogen flow rate: 35mL / min, air flow rate: 350mL / min.

[0057] Example 1

[0058] Hydrogenation process: 100g of the raw material 1,2-dihydroxy-5-cyclooctene (obtained by separation after hydration reaction of 1,2-epoxy-5-cyclooctene) is added to a 500mL high-pressure reactor, 1.0g of 40% Ni-SiO2 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:1. The reaction temperature is 150°C, the reaction pressure is 0.5MPa, and the reaction time is 1h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 100%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclooctanone accounts for 80.3%, 1-carbonylcyclooctanone accounts for 17.6%, 1,2-dihydroxycyclooctane accounts for 1.9%, and others account for 0.2%.

[0059] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 1L reactor, and add 100g formic acid and 1g phosphoric acid. Slowly add 240g of 30% hydrogen peroxide at 80°C for 0.5h, and then continue to stir and react for 1h. During the reaction, the product suberic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate and suberic acid yield of the reaction are determined by esterification derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 99.8%, and the proportion of solid products is distributed as follows: suberic acid accounts for 92.5%, pimelic acid accounts for 6.9%, 1 hexanedioic acid accounts for 0.5%, and others account for 0.1%. The actual yield of suberic acid is 91.1%.

[0060] Example 2

[0061] Hydrogenation process: 100g of the raw material 1,2-dihydroxy-5-cyclooctene (obtained by separation after hydration reaction of 1,2-epoxy-5-cyclooctene) is added to a 500mL high-pressure reactor, 2.5g of 20% Ni-Al2O3 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:4. The reaction temperature is 180°C, the reaction pressure is 0.2MPa, and the reaction time is 1.5h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 99.8%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclooctanone accounts for 82.5%, 1-carbonylcyclooctanone accounts for 16.6%, 1,2-dihydroxycyclooctane accounts for 0.5%, and others account for 0.4%.

[0062] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 1L reactor, and add 210g of acetic acid and 0.5g of concentrated sulfuric acid. Slowly add 240g of 50% hydrogen peroxide at 95°C for 1h, and then continue to stir and react for 2h. During the reaction, the product suberic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate and suberic acid yield of the reaction are determined by esterification derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 99.9%, and the proportion of solid products is distributed as follows: suberic acid accounts for 93.8%, pimelic acid accounts for 5.9%, 1-hexanodioic acid accounts for 0.3%, and others account for <0.1%. The actual yield of suberic acid is 92.4%.

[0063] Example 3

[0064] Hydrogenation process: 100g of the raw material 1,2-dihydroxy-5-cyclooctene (obtained by separation after hydration reaction of 1,2-epoxy-5-cyclooctene) is added to a 500mL high-pressure reactor, 0.6g of 10% Ni-ZrO2 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:10. The reaction temperature is 220°C, the reaction pressure is 0.95MPa, and the reaction time is 5h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 100%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclooctanone accounts for 85.6%, 1-carbonylcyclooctanone accounts for 13.3%, 1,2-dihydroxycyclooctane accounts for 0.9%, and others account for 0.2%.

[0065] Oxidation process: The hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated is placed in a 2L reactor, and 907g of dichloroacetic acid and 2.5g of p-toluenesulfonic acid are added. 92g of 60% hydrogen peroxide is slowly added dropwise at 110°C for 0.5h, and then the reaction is continued with stirring for 0.5h. During the reaction, the product suberic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate and suberic acid yield of the reaction are determined by esterification derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 100%, and the proportion of solid products is distributed as follows: suberic acid accounts for 93.1%, pimelic acid accounts for 6.2%, adipic acid accounts for 0.9%, and others account for <0.1%. The actual yield of suberic acid is 91.9%.

[0066] Table 1 Preparation of suberic acid using 1,2-dihydroxy-5-cyclooctene as raw material through tandem hydrogenation-oxidation steps

[0067]

[0068]

[0069] Example 4

[0070] Hydrogenation process: 100g of the raw material 1,2-dihydroxy-3-cyclooctene (obtained by separation after hydration reaction of 1,2-epoxy-3-cyclooctene) is added to a 500mL high-pressure reactor, 3.0g of 25% Ni-molecular sieve hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:6. The reaction temperature is 195°C, the reaction pressure is 0.3MPa, and the reaction time is 2.5h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 100%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclooctanone accounts for 96.8%, 1-carbonylcyclooctanone accounts for 0.6%, 1,2-dihydroxycyclooctane accounts for 2.3%, and others account for 0.3%.

[0071] Oxidation process: The hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated is placed in a 1L reactor, and 416g of propionic acid and 3g of heteropoly acid are added. 348g of 27.5% hydrogen peroxide is slowly added dropwise at 65°C for 1.5h, and then the reaction is continued with stirring for 0.5h. During the reaction, the product suberic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate and suberic acid yield of the reaction are determined by esterification derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 99.6%, and the proportion of solid products is distributed as follows: suberic acid accounts for 90.8%, pimelic acid accounts for 8.1%, 1 hexanedioic acid accounts for 0.9%, and the others account for less than 0.1%. The actual yield of suberic acid is 88.3%.

[0072] Example 5

[0073] Hydrogenation process: 200g of the raw material 1,2-dihydroxy-5,9-cyclododecadiene (obtained by separating 1,2-epoxy-5,9-cyclododecadiene after hydration reaction) is added to a 1L high-pressure reactor, 3.0g of 30% Ni-SiO2 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:3. The reaction temperature is 160°C, the reaction pressure is 0.6MPa, and the reaction time is 2h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 99.9%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclododecanone accounts for 86.7%, 1-carbonylcyclododecanone accounts for 12.5%, 1,2-dihydroxycyclododecane accounts for 0.7%, and the others account for less than 0.1%.

[0074] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 1L reactor, and add 244g of acetic acid and 3g of methanesulfonic acid. Slowly add 207.8g of 50% hydrogen peroxide at 85°C for 1h, and then continue to stir and react for 0.5h. During the reaction, the product dodecanedioic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate of the reaction and the yield of dodecanedioic acid are determined by esterification and derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 1006%, and the proportion of solid products is distributed as follows: dodecanedioic acid accounts for 94.3%, undecanediol accounts for 5.1%, sebacic acid accounts for 0.5%, and the others account for less than 0.1%. The actual yield of dodecanedioic acid is 93.1%.

[0075] Example 6

[0076] Hydrogenation process: 200g of the raw material 1,2-dihydroxy-5,9-cyclododecadiene (obtained by separating 1,2-epoxy-5,9-cyclododecadiene after hydration reaction) is added to a 1L high-pressure reactor, 3.0g of 60% Ni-Al2O3 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:2. The reaction temperature is 200°C, the reaction pressure is 0.8MPa, and the reaction time is 1.5h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 100%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclododecanone accounts for 84.9%, 1-carbonylcyclododecanone accounts for 14.1%, 1,2-dihydroxycyclododecane accounts for 0.8%, and others account for 0.2%.

[0077] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 1L reactor, and add 539g of butyric acid and 10g of benzenesulfonic acid. Slowly add 126g of 55% hydrogen peroxide at 100°C for 1h, and then continue to stir and react for 1h. During the reaction, the product dodecanedioic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate of the reaction and the yield of dodecanedioic acid are determined by esterification and derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 99.9%, and the proportion of solid products is distributed as follows: dodecanedioic acid accounts for 93.5%, undecanediol accounts for 5.7%, sebacic acid accounts for 0.7%, and the others account for less than 0.1%. The actual yield of dodecanedioic acid is 91.9%.

[0078] Example 7

[0079] Hydrogenation process: 200g of the raw material 1,2-dihydroxy-5,9-cyclododecadiene (obtained by separating 1,2-epoxy-5,9-cyclododecadiene after hydration reaction) is added to a 1L high-pressure reactor, 5.0g of 40% Ni-SiO2 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then a mixture of hydrogen and nitrogen is introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture is 1:5. The reaction temperature is 190°C, the reaction pressure is 0.1MPa, and the reaction time is 3h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 100%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclododecanone accounts for 87.2%, 1-carbonylcyclododecanone accounts for 12.3%, 1,2-dihydroxycyclododecane accounts for 0.4%, and the others account for less than 0.1%.

[0080] Oxidation process: The hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated is placed in a 1L reactor, and 226.2g of propionic acid and 2g of macroporous strong acid styrene cation exchange resin are added. 297g of 70% hydrogen peroxide is slowly added dropwise at 90°C for 2h, and then the reaction is continued under stirring for 1h. During the reaction, the product dodecanedioic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate of the reaction and the yield of dodecanedioic acid are determined by esterification and derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 100%, and the proportion of solid products is distributed as follows: dodecanedioic acid accounts for 93.0%, undecanediol accounts for 6.2%, sebacic acid accounts for 0.7%, and the others account for less than 0.1%. The actual yield of dodecanedioic acid is 90.8%.

[0081] Table 2 Preparation of dodecanedioic acid using 1,2-dihydroxy-5,9-cyclododecadiene as raw material through tandem hydrogenation-oxidation steps

[0082]

[0083]

[0084]

[0085] Comparative Example 1 Macrocyclic alcohol / ketone nitric acid oxidation method

[0086] 266g of 65wt% nitric acid was added to a 500mL round-bottomed flask, copper nitrate and ammonium vanadate were added to make the contents of Cu and V 0.5wt% and 0.2wt% respectively, the system was heated to a reaction temperature of 75°C by oil bath, the cyclododecanol / ketone mixture was continuously added to the flask in a molten state, the stirring state was maintained, and the reaction temperature was kept constant by controlling the oil bath temperature, 50.5g of cyclododecanol / ketone mixture (molar ratio of nitric acid / cyclododecanol ketone = 10:1) was added after 60min, crystals were precipitated, and the reaction was stopped. The obtained reaction solution was cooled to room temperature, and then the solid product was filtered out, the filter cake was washed with deionized water 2-3 times, the obtained solid was dried in a vacuum drying oven at 80°C for 8-12h, and the obtained solid mixture was finally dried and subjected to chromatographic analysis after esterification and derivatization to determine the reaction selectivity.

[0087] The reaction product ratio distribution is shown in Table 3 below:

[0088] Table 3 Comparison of reaction results between Example 5 and Comparative Example 1

[0089]

[0090]

[0091] As shown in Table 3, the traditional nitric acid oxidation process needs to undergo a diacid molecule carboxyl α-nitro or nitroso diacid intermediate, and then the intermediate is further oxidized to a dicarboxylic acid of a shorter carbon chain by decarboxylation, so that the decarboxylation reaction is carried out in series, so its by-products will include C11, C10, C9, C8, C7, C6 and the following dicarboxylic acids. At the same time, the nitric acid oxidation method has a huge heat release, and the local temperature of the reaction will be too high, which will also promote the further occurrence of side reactions. Therefore, its by-products are more, and the actual yield is only about 84-88%. The non-nitric acid green oxidation process used in the present invention, its oxidant is hydrogen peroxide, the reaction conditions are relatively mild, the reaction heat is small, and the temperature control is relatively easy, and the product is timely precipitated in the aqueous system, reducing the possibility of further decarboxylation to generate a lower carbon number dicarboxylic acid, so the selectivity of dodecanedioic acid in its product is higher than that of the nitric acid oxidation process, and has certain technical advantages.

[0092] Comparative Example 2

[0093] In the hydrogenation process, pure hydrogen gas is used instead of the hydrogen-nitrogen mixed gas, and the rest is the same as in Example 5.

[0094] Hydrogenation process: 200g of the raw material 1,2-dihydroxy-5,9-cyclododecadiene (obtained by separation after hydration reaction of 1,2-epoxy-5,9-cyclododecadiene) is added to a 1L high-pressure reactor, 3.0g of 30% Ni-SiO2 hydrogenation catalyst is added, and the air in the reactor is purged with nitrogen. Then pure hydrogen gas is introduced into the reactor. The reaction temperature is 160°C, the reaction pressure is 0.6MPa, and the reaction time is 2h. After the reaction is completed, the hydrogenation catalyst is removed by filtration or centrifugation, and the material in the reactor is directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction is 99.9%, and the product ratio distribution in the hydrogenation reaction liquid system is: 1-hydroxycyclododecanone accounts for 20.6%, 1-carbonylcyclododecanone accounts for 4.7%, 1,2-dihydroxycyclododecane accounts for 74.6%, and the others account for less than 0.1%.

[0095] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 1L reactor, and add 244g of acetic acid and 3g of methanesulfonic acid. Slowly add 207.8g of 50% hydrogen peroxide at 85°C for 1h, and then continue to stir and react for 0.5h. During the reaction, the product dodecanedioic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate of the reaction and the yield of dodecanedioic acid are determined by esterification and derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 100%, and the proportion of solid products is distributed as follows: dodecanedioic acid accounts for 83.5%, undecanediol accounts for 9.2%, sebacic acid accounts for 2.5%, and others account for 4.8%. The actual yield of dodecanedioic acid is 81.2%.

[0096] Table 4 Comparison of reaction results between Example 5 and Comparative Example 2

[0097]

[0098]

[0099] As shown in Table 4, the catalytic activity of the hydrogenation catalyst is high under a pure hydrogen environment, which makes the catalyst too strong in adsorption and dissociation of hydrogen, resulting in an excessively fast hydrogenation reaction rate, and the saturated hydrogenation product dihydroxy macrocycloalkanes account for the main component. However, this component is not conducive to the improvement of the reaction selectivity during the subsequent oxidation reaction. Therefore, it is necessary to control the hydrogenation activity of the catalyst by adjusting the ratio of nitrogen to hydrogen in the hydrogenation process stage to avoid the hydrogenolysis side reaction caused by the catalyst with higher activity, and then effectively suppress the raw material from being further excessively hydrogenated to obtain the saturated dihydroxy macrocycloalkanes byproduct after hydrogenation to generate macrocycloalkanones or macrocycloalkanols containing unsaturated carbonyl groups, thereby ensuring the high selectivity of the subsequent oxidation process and avoiding the occurrence of side reactions.

[0100] Example 8

[0101] 1,5,9-cyclododecatriene is epoxidized with 70wt% hydrogen peroxide in the presence of sodium tungstate and phosphoric acid catalyst to generate 1,2-epoxy-5,9-cyclododecadiene (selectivity is 88-92%) and 1,2-dihydroxy-5,9-cyclododecadiene (selectivity is 8-10%) and a small amount of high boiling point products. After distillation and purification, 1,2-dihydroxy-5,9-cyclododecadiene can be obtained for the preparation of dodecanedioic acid.

[0102] Hydrogenation process: 500g of the above-obtained 1,2-dihydroxy-5,9-cyclododecadiene was added to a 1L high-pressure reactor, 10g of a 30% Ni-SiO2 hydrogenation catalyst was added, and the air in the reactor was purged with nitrogen. Then a mixture of hydrogen and nitrogen was introduced into the reactor, and the ratio of hydrogen to nitrogen in the mixture was 1:5. The reaction temperature was 180°C, the reaction pressure was 0.3MPa, and the reaction time was 2h. After the reaction was completed, the hydrogenation catalyst was removed by filtration or centrifugation, and the material in the reactor was directly used in the oxidation process. According to gas chromatography analysis, the raw material conversion rate of the hydrogenation reaction was 99.9%, and the product ratio distribution in the hydrogenation reaction liquid system was: 1-hydroxycyclododecanone accounted for 87.7%, 1-carbonylcyclododecanone accounted for 11.2%, 1,2-dihydroxycyclododecane accounted for 0.9%, and the others accounted for 0.2%.

[0103] Oxidation process: Place the hydrogenation process reaction liquid from which the hydrogenation catalyst has been separated in a 3L reactor, and add 943g of propionic acid and 5g of concentrated sulfuric acid. Slowly add 520g of 50% hydrogen peroxide at 85°C for 1h, and then continue to stir and react for 1h. During the reaction, the product dodecanedioic acid gradually precipitates. After the reaction is completed, the reaction liquid is cooled to room temperature, the crystalline solid is filtered out, and the conversion rate of the reaction and the yield of dodecanedioic acid are determined by esterification and derivatization. According to gas chromatography analysis, the raw material conversion rate of the oxidation reaction is 100%, and the proportion of solid products is distributed as follows: dodecanedioic acid accounts for 94.1%, undecanediol accounts for 5.3%, sebacic acid accounts for 0.5%, and the others account for less than 0.1%. The actual yield of dodecanedioic acid is 92.6%. By simply cooling and crystallizing the obtained solid in an appropriate solvent such as methanol or acetic acid, a high-quality dodecanedioic acid product can be obtained, with a monoacid purity of 99.6%, a moisture content of 0.032%, a total nitrogen content of 12 ppm, an Fe ion content of 0.1 ppm, and an ash content of 18 ppm.

[0104] Polymerization process: Take 500g of the above-mentioned refined dodecanedioic acid and dissolve it in 4-8 times the mass weight of anhydrous ethanol, heat it to 80°C, and dissolve the dodecanedioic acid completely. Add 70% hexamethylenediamine-ethanol solution under stirring to form salt (hexamethylenediamine and dodecanedioic acid are in equal molar proportions). During the salt-forming process, the temperature is maintained at about 80°C, and the pH value at the end point is 7.4. Cool to room temperature, filter, and dry to obtain 750g of white crystalline nylon 612 salt. Add the above nylon 612 salt, 130g of water, 2g of molecular regulator and 0.6g of antioxidant into the polymerization reactor, start heating to 200°C after nitrogen replacement, and the pressure in the reactor rises to 1.5MPa, and maintain the reaction for 2-3h. Then reduce the pressure to atmospheric pressure, and at the same time, the temperature rises to 250°C, and vent at normal pressure for 2h. Finally, after the venting is completed, vacuumize for 20-60min, and the vacuum degree is 0.5-0.6MPa. After the reaction is completed, the molten polymer is extruded, cooled and pelletized to obtain nylon 612 resin. The product properties are shown in Table 5.

[0105] Table 5 Performance comparison of nylon 612 prepared by polymerization in Example 8 and commercially available nylon 612 products

[0106] Test items Commercially available nylon 612 Example 8 Preparation of Nylon 612 <![CDATA[Density (g / cm 3 )]]> 1.07 1.069 Melting point(℃) 218 217.2 Tensile strength(MPa) 74 62.3 Elastic modulus (MPa) 1900 2154 Elongation at break 23℃(%) ≥200 267 Bending strength(MPa) 82 79.4 Flexural modulus (MPa) 2900 2965 Notched impact strength (J / m) 75 76.2 Heat deformation temperature 0.46MPa(℃) 180 183.8 Rockwell hardness (R) 114 112 Water absorption (23℃, in water, 24h) (%) 0.25 0.32

[0107] As can be seen from Example 8, when the raw material is obtained by separation as a byproduct when preparing epoxy macrocyclic olefins through epoxidation reaction with macrocyclic olefins, the tandem hydrogenation-oxidation process described in the present invention can also obtain good selectivity and yield of long carbon chain dicarboxylic acids, and is better than the nitric acid oxidation process. The existing byproducts are used as raw materials to transform into long carbon chain dicarboxylic acids with high economic value, which improves atom economy, realizes the transformation of waste into treasure, reduces production costs, maximizes its economic benefits, and enhances the competitiveness of the entire long carbon chain product industry chain. In addition, polymerization-grade long carbon chain dicarboxylic acid products can be obtained by simple crystallization, and the various product performance parameters of the obtained nylon 612 resin are consistent with the performance parameters of currently commercially available products through melt polymerization with hexamethylenediamine.

Claims

1. A method for preparing a long carbon chain dicarboxylic acid, characterized in that: The following steps are involved: S1: heating a dihydroxy macrocyclic olefin and a hydrogenation catalyst in a hydrogen-containing gas atmosphere until the reaction is complete to obtain a hydrogenation product; the hydrogen-containing gas is a mixture of hydrogen and nitrogen; the volume ratio of hydrogen to nitrogen in the mixture is 1:3-5; the main metal of the hydrogenation catalyst is a nickel-based metal, and the carrier is silicon dioxide; S2: mixing the hydrogenation product, oxidation catalyst, oxidation aid, and oxidant until the reaction is complete to obtain the desired long carbon chain dicarboxylic acid; The dihydroxy macrocyclic olefin is a cyclic olefin containing 8 to 12 carbon atoms and having at least one carbon-carbon unsaturated double bond with the dihydroxyl group being in the ortho position; The oxidant is a hydrogen peroxide solution; The oxidation aid is one or more of formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid, isovaleric acid, pivalic acid, chloroacetic acid, and dichloroacetic acid; The oxidation catalyst is sulfuric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, SO4 2- / M x O y One or more of a type solid superacid, a Keggin structure heteropolyacid, a macroporous strong acid styrene-based cation exchange resin, and a perfluorosulfonic acid resin.

2. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The mass of the hydrogenation catalyst is 0.01-5% of the mass of the dihydroxy macrocyclic olefin.

3. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The mass of the hydrogenation catalyst is 0.1-3% of the mass of the dihydroxy macrocyclic olefin.

4. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The mass of the hydrogenation catalyst is 0.5-2% of the mass of the dihydroxy macrocyclic olefin.

5. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S1 is 50-250° C., the reaction pressure is 0.1-5 MPa, and the reaction time is 0.1-5 h.

6. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S1 is 100-230° C., the reaction pressure is 0.1-2 MPa, and the reaction time is 0.5-3 h.

7. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S1 is 150-220° C., the reaction pressure is 0.1-1 MPa, and the reaction time is 1-2 h.

8. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The concentration of the oxidant is 10-75%, and the molar ratio of the hydrogenation product to hydrogen peroxide is 1:1-10.

9. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The concentration of the hydrogen peroxide solution is 30-70%, and the molar ratio of the hydrogenation product to the hydrogen peroxide is 1:1-5.

10. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The concentration of the hydrogen peroxide solution is 50-60%, and the molar ratio of the hydrogenation product to the hydrogen peroxide is 1:2-3.

11. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The molar ratio of the oxidation aid to the hydrogenation product is (1-20):

1.

12. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The molar ratio of the oxidation aid to the hydrogenation product is (2-10):

1.

13. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The molar ratio of the oxidation aid to the hydrogenation product is (3-5):

1.

14. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The amount of the oxidation catalyst added is 0.1-10 wt % of the hydrogenation product.

15. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The amount of oxidation catalyst added is 0.5-6 wt % of the hydrogenation product.

16. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The oxidation catalyst is one or more of sulfuric acid, p-toluenesulfonic acid, phosphotungstic acid, and macroporous strong acid styrene cation exchange resin, and the added amount of the oxidation catalyst is 1-3wt% of the hydrogenation product.

17. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S2 is 50-120° C., and the reaction time is 0.5-5 h.

18. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S2 is 60-100° C., and the reaction time is 1-3 h.

19. The method for preparing a long carbon chain dicarboxylic acid according to claim 1, characterized in that: The reaction temperature of step S2 is 70-90°C.

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