Method for preparing 1, 4-cyclohexanedimethanol through continuous hydrogenation of 1, 4-cyclohexanedicarboxylic acid

Abstract

The invention provides a method for preparing 1, 4-cyclohexanedimethanol through continuous hydrogenation of 1, 4-cyclohexanedicarboxylic acid. According to the method, under a specific catalyst and preset reaction conditions, a 1, 4-cyclohexanedicarboxylic acid aqueous solution reacts with hydrogen to generate a hydrogenation solution containing 1, 4-cyclohexanedimethanol, the preset reaction conditions are as follows: the reaction temperature is 210-230 DEG C, the reaction pressure is 6-12 MPa, the catalyst comprises a first metal Ru, a second metal Sn, a first auxiliary metal M1, a second auxiliary metal M2 and a carrier, and the first auxiliary metal M1 and the second auxiliary metal M2 are used as raw materials. The metal M1 is selected from one of Pd, Pt and Rh, and the metal M2 is selected from one of Co, Mn and W. According to the catalyst provided by the invention, by adding the second aid M2, the particle size of the RuSn alloy can be reduced, the activity of the catalyst is improved (the CHDA conversion rate reaches 99.5% or above, and the CHDM selectivity reaches 98.5% or above), meanwhile, the toxic action of Ni, Fe and other metals introduced by corrosion of a reactor on the catalyst can be delayed, and the stability of the catalyst is improved (the one-way operation life of the catalyst is 3000 h or above).

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and specifically relates to a method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid. Background Art

[0002] 1,4-cyclohexanedimethanol (CHDM) is an important raw material for polyester production. The polyethylene terephthalate (PET) resin modified by CHDM copolymerization has a slow crystallization rate and good processing and physical properties. In particular, the polyester modified by trans-CHDM has a high glass transition temperature and softening temperature, good chemical resistance and environmental adaptability, and a wide range of applications. At present, the main process for industrial production of CHDM uses dimethyl terephthalate as raw material. First, the benzene ring is hydrogenated to produce 1,4-cyclohexanedicarboxylic acid dimethyl ester, and 1,4-cyclohexanedicarboxylic acid dimethyl ester is further hydrogenated to prepare CHDM. In comparison, the cost of terephthalic acid (PTA) is lower than that of dimethyl terephthalate raw material, and the raw material source is more abundant. Therefore, the preparation of CHDM by two-step hydrogenation using PTA as raw material has become a research trend in recent years.

[0003] The preparation of CHDM by hydrogenation of terephthalic acid (PTA) mostly adopts a two-step process, firstly, the PTA benzene skeleton is hydrogenated to produce CHDA under the action of a catalyst, and the generated CHDA is further subjected to carboxyl hydrogenation under the action of a catalyst to produce CHDM. The reaction of hydrogenating PTA to produce CHDA generally adopts Pd / C as a catalyst, and the CHDA yield is generally higher than 95%. For the second step of CHDA hydrogenation to CHDM reaction, higher requirements are placed on the catalyst. The classic catalyst used for the preparation of corresponding alcohol compounds by hydrogenation of carboxylic acids is a Ru-Sn bimetallic catalyst. For example, the document (Appl. Catal. A: Gen. 302 (2006) 208-214) prepared a Ru-Sn / Al2O3 catalyst for CHDA hydrogenation to produce CHDM in a reactor, with a raw material CHDA conversion rate of 99.2% and a product CHDM yield of 97.9%. However, when applied to the fifth reactor, the CHDM yield dropped sharply to 84.2%. Further studies have shown that the introduction of Pt into the Ru-Sn bimetallic system can significantly inhibit the loss of Sn on the catalyst, thereby improving the catalyst performance (Appl. Catal. A: Gen. 239 (2003) 181-195). In addition, the reaction temperature of CHDA hydrogenation to CHDM is generally high (230-240°C), and the raw material CHDA has strong acidity at high temperatures (especially with water as a solvent), which corrodes various stainless steel reactors to a certain extent. Various metal ions, such as Ni and Fe, dissolve in the reaction solution and are eventually adsorbed on the catalyst, causing the catalyst performance to deteriorate (Yoshiaki T., et al. US 5430184, 1995.). Summary of the invention

[0004] The purpose of the present invention is to improve a method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid using a novel catalyst Ru-Sn-M1-M2 / C. The catalyst can maintain high activity for a long time during use and has good stability.

[0005] In order to achieve the above object, the present invention provides a method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid. Under a specific catalyst and preset reaction conditions, an aqueous solution of 1,4-cyclohexanedicarboxylic acid reacts with hydrogen to generate a hydrogenated liquid including 1,4-cyclohexanedimethanol. The preset reaction conditions include: a reaction temperature of 210 to 230° C., a reaction pressure of 6 MPa to 12 MPa, and the catalyst includes:

[0006] The first metal Ru, based on the total weight of the catalyst as 100%, the theoretical loading amount of the first metal Ru is 1 to 9 wt%;

[0007] The second metal Sn, based on the total weight of the catalyst as 100%, the theoretical loading amount of the second metal Sn is 1 to 10 wt%;

[0008] A first auxiliary metal M1, wherein the metal M1 is selected from one of Pd, Pt and Rh, and the theoretical loading amount of the metal M1 is 0.1-3.0 wt% based on the total weight of the catalyst as 100%;

[0009] A second promoter metal M2, wherein the metal M2 is selected from one of Co, Mn and W, and the theoretical loading amount of the metal M2 is 0.05-5.0 wt% based on the total weight of the catalyst as 100%;

[0010] Carrier C is pretreated activated carbon, and the total weight of the first metal Ru, the second metal Sn, the first auxiliary metal M1, the second auxiliary metal M2 and the carrier is 100%.

[0011] In a specific embodiment, the catalyst is one of Ru-Sn-Pt-Co / C, Ru-Sn-Pt-Mn / C and Ru-Sn-Pt-W / C.

[0012] In a specific embodiment, the catalyst is one of Ru-Sn-Pd-Co / C, Ru-Sn-Pd-Mn / C and Ru-Sn-Pd-W / C.

[0013] In a specific embodiment, the catalyst is one of Ru-Sn-Rh-Co / C, Ru-Sn-Rh-Mn / C and Ru-Sn-Rh-W / C.

[0014] In a specific embodiment, based on the total weight of the catalyst as 100%, the total loading amount of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 in the catalyst is 10wt~15wt%, and the mass ratio of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 is: 6: (4~5): 1.5: (0.5~1.5).

[0015] In a specific embodiment, the pretreatment of the activated carbon carrier is: placing the activated carbon in a nitric acid solution for acid treatment to introduce oxygen-containing groups including carboxyl groups on the surface of the activated carbon, and the acid treatment conditions include: treatment temperature of 60 to 95°C, treatment time of 0.5 to 8h, preferably, the treatment temperature is 90 to 95°C.

[0016] In a specific embodiment, the mass ratio of the activated carbon to the nitric acid solution is 1:(2-10), and the mass percentage concentration of the nitric acid solution is 10-20%, preferably, the mass percentage concentration of the nitric acid solution is 15%.

[0017] In a specific embodiment, the preparation method of the catalyst comprises: first preparing a catalyst precursor by an equal volume impregnation method, and then reducing the catalyst precursor with a reducing agent to obtain the catalyst, wherein the reducing agent is hydrogen, and the reduction treatment conditions include: 150-500°C, preferably 300-400°C; hydrogen volume space velocity 50-500h -1 , preferably 100 to 200 hours -1 .

[0018] In a specific embodiment, the preset reaction conditions also include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.05 to 2.0 h -1 The molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 5.0 to 80.0; preferably, the preset reaction conditions include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.8 to 1.2 h -1 , the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 10-30, the reaction temperature is 220°C, and the reaction pressure is 8MPa-9MPa.

[0019] In a specific embodiment, during the hydrogenation reaction, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be adjusted by controlling the reaction temperature, the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid, and the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid.

[0020] The beneficial effects of the present invention include at least:

[0021] 1. In view of the technical problem that the catalyst RuSn / C in the hydrogenation reaction of 1,4-cyclohexanedicarboxylic acid has low catalytic activity and poor stability, the present invention provides a novel catalyst Ru-Sn-M1-M2 / C for catalyzing the continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid to prepare 1,4-cyclohexanedimethanol. The activity and stability of the catalyst are improved by introducing a first auxiliary metal M1 and a second metal auxiliary M2. Specifically, the metal M1 is one of Pd, Pt, and Rh, and the main purpose is to stabilize the metal Sn and inhibit the loss of Sn during the reaction; the metal M2 is one of Co, Mn, and W, which can reduce the particle size of the RuSn alloy and improve the hydrogenation activity of the catalyst on the one hand, and on the other hand, serve as an electronic auxiliary to stabilize the RuSn alloy and avoid reaction with Ni, Fe and other ions in the solution to cause changes in the active center of the catalyst.

[0022] 2. In the preparation of the catalyst of the present invention, the activated carbon carrier is treated with nitric acid to enhance the hydrophilicity of the carrier, and oxygen-containing groups are introduced on its surface to enhance the adsorption of the metal precursor on the activated carbon carrier.

[0023] 3. The Ru-Sn-M1-M2 / C catalyst prepared by the present invention not only has a small metal particle size and a stable structure, but also has the ability to resist poisoning by Ni, Fe and other ions in the reaction solution. When it is applied to the hydrogenation reaction of 1,4-cyclohexanedicarboxylic acid to prepare 1,4-cyclohexanedimethanol, the conversion rate of 1,4-cyclohexanedicarboxylic acid reaches more than 99.5%, and the selectivity of the product 1,4-cyclohexanedimethanol reaches more than 98.5%. The catalyst performance is stable and can operate stably for more than 3000 hours.

[0024] 4. Trans-1,4-cyclohexanedimethanol has important applications as a polyester resin monomer. The present invention finds that, based on the catalyst provided by the present invention, the reaction temperature and the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid are positively correlated with the proportion of trans-1,4-cyclohexanedicarboxylic acid in the hydrogenated liquid, and are negatively correlated with the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid. That is to say, by controlling the increase in the reaction temperature and the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid, or controlling the decrease in the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be increased; in this way, the proportion of trans-1,4-cyclohexanedimethanol in the reaction product can be controlled, and the application value of the reaction product of the present invention can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The life evaluation test results of catalyst Cat.-4 prepared in Catalyst Example A4 and catalyst Cat.-20 prepared in Example A20. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and embodiments, but the present invention can be implemented in many different ways as limited and covered by the claims.

[0027] The invention provides a method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid. Under a specific catalyst and preset reaction conditions, an aqueous solution of 1,4-cyclohexanedicarboxylic acid reacts with hydrogen to generate a hydrogenated liquid including 1,4-cyclohexanedimethanol.

[0028] Specifically, raw materials CHDA and purified water are first put into an autoclave, and CHDA is dissolved at a high temperature (140-220°C); then the materials are transported to a fixed bed reactor by a high-temperature pump, and the 1,4-cyclohexanedicarboxylic acid aqueous solution undergoes a hydrogenation reaction under the action of a catalyst to generate a hydrogenated liquid including 1,4-cyclohexanedimethanol; after the hydrogenated liquid is separated from gas and liquid, it is cooled to obtain a CHDM hydrogenated liquid.

[0029] In the present invention, the fixed bed reactor is a gas-liquid-solid three-phase trickle bed reactor.

[0030] Preferably, the mass percentage of the 1,4-cyclohexanedicarboxylic acid solution is 0.5-40%.

[0031] In the present invention, the catalyst includes: a first metal Ru, the theoretical loading amount of the first metal Ru is 1 to 9 wt% based on the total weight of the catalyst being 100%; a second metal Sn, the theoretical loading amount of the second metal Sn is 1 to 10 wt% based on the total weight of the catalyst being 100%; a first auxiliary metal M1, the metal M1 is selected from one of Pd, Pt and Rh, and the theoretical loading amount of the metal M1 is 0.1 to 3.0 wt% based on the total weight of the catalyst being 100%; a second auxiliary metal M2, the metal M2 is selected from one of Co, Mn and W, and the theoretical loading amount of the metal M2 is 0.05 to 5.0 wt% based on the total weight of the catalyst being 100%; and a carrier C, which is pretreated activated carbon, the total weight of the first metal Ru, the second metal Sn, the first auxiliary metal M1, the second auxiliary metal M2 and the carrier being 100%.

[0032] Preferably, based on the total weight of the catalyst as 100%, the total loading amount of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 in the catalyst is 10wt~15wt%, and the mass ratio of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 is: 6:(4~5):1.5:(0.5~1.5).

[0033] When the total loading of the four metals in the catalyst is within 10wt% to 15wt% and the mass is in the above ratio, the catalytic activity of the catalyst is the best.

[0034] Preferably, the catalyst may be one of Ru—Sn—Pt—Co / C, Ru—Sn—Pt—Mn / C and Ru—Sn—Pt—W / C.

[0035] Preferably, the catalyst may be one of Ru—Sn—Pd—Co / C, Ru—Sn—Pd—Mn / C and Ru—Sn—Pd—W / C.

[0036] Preferably, the catalyst may be one of Ru—Sn—Rh—Co / C, Ru—Sn—Rh—Mn / C and Ru—Sn—Rh—W / C.

[0037] Preferably, the method for preparing the catalyst comprises: firstly preparing a catalyst precursor by an equal volume impregnation method, and then reducing the catalyst precursor with a reducing agent to obtain the catalyst.

[0038] The equal volume impregnation method is specifically as follows: the precursors of metals Ru, Sn, M1, and M2 are prepared into an aqueous solution, adsorbed on an activated carbon carrier, left to stand for 24 to 36 hours, and dried to obtain a catalyst precursor.

[0039] In the present invention, the drying conditions are: drying temperature 60-120° C., and drying time 2-8 hours.

[0040] In the present invention, the precursor of metal Ru is one of ruthenium trichloride, ruthenium nitrate, and ruthenium acetate; the precursor of metal Sn is one of tin tetrachloride, stannous chloride, and stannous oxalate; the precursor of metal Pd is one of palladium chloride, palladium nitrate, and palladium acetate; the precursor of metal Pt is one of chloroplatinic acid, platinum nitrate, and platinum acetate; the precursor of metal Rh is one of rhodium chloride, rhodium nitrate, and rhodium acetylacetonate; the precursor of metal Co is one of cobalt chloride, cobalt acetate, and cobalt nitrate; the precursor of metal Mn is one of manganese chloride, manganese nitrate, and manganese acetate; the precursor of metal W is one of tungstic acid and ammonium tungstate.

[0041] Preferably, the reducing agent is hydrogen, and the reduction treatment conditions include: 150-500°C, preferably 300-400°C; hydrogen volume space velocity 50-500h -1 , preferably 100 to 200 hours -1 .

[0042] Preferably, the pretreatment of the activated carbon carrier is: placing the activated carbon in a nitric acid solution for acid treatment to introduce oxygen-containing groups including carboxyl groups on the surface of the activated carbon, and the acid treatment conditions include: treatment temperature of 60 to 95°C and treatment time of 0.5 to 8h. Preferably, the treatment temperature is 90 to 95°C.

[0043] Preferably, the mass ratio of the activated carbon to the nitric acid solution is 1:(2-10), and the mass percentage concentration of the nitric acid solution is 10-20%, preferably, the mass percentage concentration of the nitric acid solution is 15%.

[0044] Preferably, the preset reaction conditions include: reaction temperature of 210-230°C, reaction pressure of 6MPa-12MPa, feed mass space velocity of 1,4-cyclohexanedicarboxylic acid of 0.05-2.0h -1 , the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 5.0 to 80.0.

[0045] More preferably, the preset reaction conditions include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.8 to 1.2 h -1 , the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 10-30, the reaction temperature is 220°C, and the reaction pressure is 8MPa-9MPa.

[0046] More preferably, the preset reaction conditions include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.8 to 1.0 h -1 , the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 20, the reaction temperature is 220°C, and the reaction pressure is 8 MPa.

[0047] Preferably, during the hydrogenation reaction, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be adjusted by controlling the reaction temperature, the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid, and the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid.

[0048] More preferably, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be increased by controlling the reaction temperature or increasing the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid.

[0049] That is, in the present invention, the reaction temperature or the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is positively correlated with the ratio of trans-1,4-cyclohexanedimethanol.

[0050] More preferably, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be increased by reducing the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid.

[0051] That is, in the present invention, the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is negatively correlated with trans-1,4-cyclohexanedimethanol.

[0052] In the present invention, the yield of trans-1,4-cyclohexanedimethanol can be controlled by adjusting the hydrogenation reaction conditions, thereby increasing the application value of the reaction product 1,4-cyclohexanedimethanol.

[0053] In the present invention, the method further comprises a post-treatment step, wherein the hydrogenated liquid is subjected to gas-liquid separation to obtain 1,4-cyclohexanedimethanol hydrogenated liquid.

[0054] 1. Preparation of catalyst

[0055] 1.1 Preparation of dimetallic catalyst (without addition of first and second additives)

[0056] Example A1

[0057] Carrier: Untreated activated carbon flakes (Carbon-0) were used as carrier.

[0058] Preparation of catalyst:

[0059] The catalyst was prepared by an equal volume impregnation method. Ruthenium chloride and tin tetrachloride solutions were prepared according to the theoretical loading amount and impregnated on the untreated activated carbon support for 24 h. After drying at 110 ° C for 6 h and hydrogen reduction, the catalyst was obtained, which was recorded as Cat.-1. The conditions for hydrogen reduction were: hydrogen volume space velocity 200 h -1 , reduction temperature is 400°C; the theoretical loading amount of Ru is 6.0wt%, and the theoretical loading amount of Sn is 5.0wt%.

[0060] Example A2

[0061] Preparation of the carrier: The flaky activated carbon carrier (Carbon-0) was pretreated with a nitric acid solution, the concentration of the nitric acid solution was 15.0wt%, the mass ratio of the activated carbon carrier to the nitric acid solution was 1:4, the nitric acid treatment temperature was 90°C, and the nitric acid treatment time was 3h; after the nitric acid pretreatment, the activated carbon carrier was washed with purified water until the filtrate was neutral, and dried at 110°C for 6h. The obtained activated carbon sample was recorded as Carbon-1.

[0062] Preparation of catalyst:

[0063] The catalyst was prepared by an equal volume impregnation method. Ruthenium chloride and tin tetrachloride solutions were prepared according to the theoretical loading amount and impregnated on the activated carbon carrier Carbon-1 treated with nitric acid for 24 hours. After drying at 110°C for 6 hours and hydrogen reduction, a catalyst was obtained, which was recorded as Cat.-2. The conditions for hydrogen reduction were: hydrogen volume space velocity 200 h -1 , reduction temperature is 400°C; the theoretical loading amount of Ru is 6.0wt%, and the theoretical loading amount of Sn is 5.0wt%.

[0064] 1.2 Preparation of trimetallic catalyst (without adding second auxiliary agent)

[0065] Example A3

[0066] Carrier: Untreated activated carbon flakes (Carbon-0) were used as carrier.

[0067] Preparation of catalyst:

[0068] The catalyst was prepared by an equal volume impregnation method. Ruthenium chloride, tin tetrachloride and chloroplatinic acid solutions were prepared according to the theoretical loading amount and impregnated on the above untreated activated carbon carrier for 24 hours. After drying at 110°C for 6 hours and hydrogen reduction, the catalyst was obtained, which was recorded as Cat.-3. The conditions for hydrogen reduction were: hydrogen volume space velocity 200 h -1, reduction temperature 400°C; the theoretical loading amount of Ru is 6.0wt%, the theoretical loading amount of Sn is 5.0wt%, and the theoretical loading amount of Pt is 1.5wt%.

[0069] Example A4

[0070] Preparation of the carrier: The flaky activated carbon carrier (Carbon-0) was pretreated with a nitric acid solution, the concentration of the nitric acid solution was 15.0wt%, the mass ratio of the activated carbon carrier to the nitric acid solution was 1:4, the nitric acid treatment temperature was 90°C, and the nitric acid treatment time was 3h; after the nitric acid pretreatment, the activated carbon carrier was washed with purified water until the filtrate was neutral, and dried at 110°C for 6h. The obtained modified activated carbon sample was recorded as Carbon-1.

[0071] The preparation of this vector is the same as that of the vector in Example A2, so the vector numbers are the same.

[0072] Preparation of catalyst:

[0073] The catalyst was prepared by an equal volume impregnation method. Ruthenium chloride, tin tetrachloride and chloroplatinic acid solutions were prepared according to the theoretical loading amount and impregnated on the activated carbon carrier Carbon-1 treated with nitric acid for 24 hours. After drying at 110°C for 6 hours and reducing with hydrogen, a catalyst was obtained, which was recorded as Cat.-4. The conditions for hydrogen reduction were: hydrogen volume space velocity 200 h -1 , reduction temperature 400°C; the theoretical loading amount of Ru is 6.0wt%, the theoretical loading amount of Sn is 5.0wt%, and the theoretical loading amount of Pt is 1.5wt%.

[0074] Example A5

[0075] Example A5 is the same as Example A4, the only difference being that the concentration of the nitric acid solution when preparing the carrier is 10wt%, and the activated carbon sample obtained is recorded as Carbon-2; the carrier used in the catalyst preparation step is Carbon-2, and the obtained catalyst is recorded as Cat.-5.

[0076] Example A6

[0077] Example A5 is the same as Example A4, the only difference being that the concentration of the nitric acid solution when preparing the carrier is 20wt%, and the activated carbon sample obtained is recorded as Carbon-3; the carrier used in the catalyst preparation step is Carbon-3, and the obtained catalyst is recorded as Cat.-6.

[0078] Example A7

[0079] Example A7 is the same as Example A4, the only difference being that the nitric acid treatment temperature is 80°C when preparing the carrier, and the activated carbon sample obtained is recorded as Carbon-4; the carrier used in the catalyst preparation step is Carbon-4, and the obtained catalyst is recorded as Cat.-7.

[0080] Example A8

[0081] Example A8 is the same as Example A4, the only difference being that the nitric acid treatment temperature is 98°C when preparing the carrier, and the activated carbon sample obtained is recorded as Carbon-5; the carrier used in the catalyst preparation step is Carbon-5, and the obtained catalyst is recorded as Cat.-8.

[0082] Embodiment A9

[0083] Example A9 is the same as Example A4, the only difference being that the activated carbon used in preparing the carrier is columnar activated carbon, and the obtained activated carbon sample is recorded as Carbon-6; the carrier used in the catalyst preparation step is Carbon-6, and the obtained catalyst is recorded as Cat.-9.

[0084] Embodiment A10

[0085] Example A10 is the same as Example A4, except that the carrier used in the catalyst preparation step is Carbon-1, and the difference is that the first auxiliary agent added is changed from platinum to palladium, and the obtained catalyst is recorded as Cat.-10.

[0086] Embodiment A11

[0087] Example A11 is the same as Example A4, except that the carrier used in the catalyst preparation step is Carbon-1, and the difference is that the first auxiliary agent added is changed from platinum to rhodium, and the obtained catalyst is recorded as Cat.-11.

[0088] Example A12

[0089] Example A12 is the same as Example A4, and the carrier adopted in the catalyst preparation step is Carbon-1. The difference is that the theoretical loading amounts of the added first metal Ru, the second metal Sn and the first auxiliary metal Pt are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A12: the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 4.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%.

[0090] The catalyst prepared in Example A12 is denoted as Cat.-12.

[0091] Embodiment A13

[0092] Example A13 is the same as Example A4, and the carrier adopted in the catalyst preparation step is Carbon-1. The difference is that the theoretical loading amounts of the first metal Ru, the second metal Sn and the first auxiliary metal Pt added are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A13: the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 6.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%.

[0093] The catalyst prepared in Example A13 is denoted as Cat.-13.

[0094] Embodiment A14

[0095] Example A14 is the same as Example A4, and the carrier adopted in the catalyst preparation step is Carbon-1, the difference being that the theoretical loading amounts of the added first metal Ru, the second metal Sn and the first auxiliary metal Pt are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A14: the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 2.0wt%.

[0096] The catalyst prepared in Example A14 is denoted as Cat.-14.

[0097] Embodiment A15

[0098] Example A14 is the same as Example A4, and the carrier adopted in the catalyst preparation step is Carbon-1, the difference being that the theoretical loading amounts of the added first metal Ru, the second metal Sn and the first auxiliary metal Pt are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A14: the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.0wt%.

[0099] The catalyst prepared in Example A15 is denoted as Cat.-15.

[0100] Embodiment A16

[0101] Example A14 is the same as Example A4, except that the carrier adopted in the catalyst preparation step is Carbon-1, and the difference is that the theoretical loading amounts of the added first metal Ru, the second metal Sn and the first auxiliary metal Pt are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A14: the theoretical loading amount of the first metal Ru is 3.0wt%, the theoretical loading amount of the second metal Sn is 2.5wt% and the theoretical loading amount of the first auxiliary metal Pt is 0.75wt%.

[0102] The catalyst prepared in Example A16 is denoted as Cat.-16.

[0103] Embodiment A17

[0104] Example A17 is the same as Example A4, and the carrier adopted in the catalyst preparation step is Carbon-1. The difference is that the theoretical loading amounts of the added first metal Ru, the second metal Sn and the first auxiliary metal Pt are different. In Example A4, the theoretical loading amount of the first metal Ru is 6.0wt%, the theoretical loading amount of the second metal Sn is 5.0wt% and the theoretical loading amount of the first auxiliary metal Pt is 1.5wt%; in Example A14: the theoretical loading amount of the first metal Ru is 1.5wt%, the theoretical loading amount of the second metal Sn is 1.25wt% and the theoretical loading amount of the first auxiliary metal Pt is 0.375wt%.

[0105] The catalyst prepared in Example A17 is denoted as Cat.-17.

[0106] Table 1 Sequence number and composition of dimetallic catalyst and trimetallic catalyst

[0107]

[0108]

[0109] Note: Carbon-6 is columnar activated carbon

[0110] It should be noted that Cat.-1 and Cat.-2 in Table 1 are bimetallic catalysts without additives, and Cat.-3 to Cat.-17 are trimetallic catalysts with the first additive added. Among them, the theoretical metal loading amounts of the first metal, the second metal and the first additive Pt added to Cat.-3 to Cat.-8 are exactly the same, the difference lies in the concentration of nitric acid or the nitric acid treatment temperature when the carrier is treated with nitric acid; the carriers added to catalysts Cat.-4, Cat.-10 and Cat.-11 are exactly the same, the difference mainly lies in the first additive; the carriers added to catalysts Cat.-4, Cat.-12 to Cat.-17 are exactly the same, the difference lies in the theoretical metal loading amounts of the first metal, the second metal and the first additive Pt added are different.

[0111] 1.3 Preparation of tetrametallic catalysts

[0112] Embodiment A18

[0113] Preparation of the carrier: The flaky activated carbon carrier (Carbon-0) was pretreated with a nitric acid solution, the concentration of the nitric acid solution was 15.0wt%, the mass ratio of the activated carbon carrier to the nitric acid solution was 1:4, the nitric acid treatment temperature was 90°C, and the nitric acid treatment time was 3h; after the nitric acid pretreatment, the activated carbon carrier was washed with purified water until the filtrate was neutral, and dried at 110°C for 6h. The obtained modified activated carbon sample was recorded as Carbon-1.

[0114] The preparation of this vector is the same as that of the vector in Example A2, so the vector numbers are the same.

[0115] Preparation of catalyst:

[0116] The catalyst was prepared by an equal volume impregnation method. Ruthenium chloride, tin tetrachloride, chloroplatinic acid solution and manganese acetate were prepared according to the theoretical loading amount and impregnated on the activated carbon carrier Carbon-1 treated with nitric acid for 24 hours. After drying at 110°C for 6 hours and hydrogen reduction, the catalyst was obtained, which was recorded as Cat.-18. The conditions for hydrogen reduction were: hydrogen volume space velocity 200 h -1 , reduction temperature 400°C; the theoretical loading amount of Ru is 6.0wt%, the theoretical loading amount of Sn is 5.0wt%, the theoretical loading amount of Pt is 1.5wt%, and the theoretical loading amount of Mn is 1.0wt%.

[0117] Embodiment A19

[0118] Example A19 is the same as Example A18, except that the carrier used in the catalyst preparation step is Carbon-1, and the difference is that the second auxiliary agent added is changed from manganese to tungsten, and the obtained catalyst is recorded as Cat.-19.

[0119] It should be noted that the precursor of tungsten is ammonium tungstate.

[0120] Example A20

[0121] Example A20 is the same as Example A18, except that the carrier used in the catalyst preparation step is Carbon-1, and the difference is that the second auxiliary agent added is changed from manganese to cobalt, and the obtained catalyst is recorded as Cat.-20.

[0122] It should be noted that the cobalt precursor is cobalt acetate.

[0123] Example A21

[0124] Example A21 is the same as Example A20, and the carrier used in the catalyst preparation step is Carbon-1. The difference is that the theoretical loading amount of the second auxiliary metal cobalt added is different. In Example A20, the theoretical loading amount of Co is 1.0wt%, and in Example A21, the theoretical loading amount of Co is 0.5wt%.

[0125] The catalyst prepared in Example A21 is denoted as Cat.-21.

[0126] Example A22

[0127] Example A22 is the same as Example A20, and the carrier used in the catalyst preparation step is Carbon-1. The difference is that the theoretical loading amount of the second auxiliary metal cobalt added is different. In Example A20, the theoretical loading amount of Co is 1.0wt%, and in Example A22, the theoretical loading amount of Co is 1.5wt%.

[0128] The catalyst prepared in Example A22 is denoted as Cat.-22.

[0129] Example A23

[0130] Example A23 is the same as Example A20, and the carrier used in the catalyst preparation step is Carbon-1. The difference is that when the catalyst precursor is reduced, the reduction temperature is different. In Example A20, the reduction temperature is 400°C, and in Example A23, the reduction temperature is 300°C.

[0131] The catalyst prepared in Example A23 is recorded as Cat.-23.

[0132] Example A24

[0133] Example A24 is the same as Example A20, and the carrier used in the catalyst preparation step is Carbon-1. The difference is that when the catalyst precursor is reduced, the reduction temperature is different. In Example A20, the reduction temperature is 400°C, and in Example A24, the reduction temperature is 500°C.

[0134] The catalyst prepared in Example A24 is denoted as Cat.-24.

[0135] Table 2 Sequence number and composition of four metal catalysts

[0136]

[0137]

[0138] 2. Catalyst evaluation

[0139] 2.1 Investigating the effects of nitric acid treatment concentration and treatment temperature on catalyst activity

[0140] In the present invention, the CHDA hydrogenation reaction to CHDM is carried out according to the following steps: raw material CHDA and purified water are added to an autoclave, and CHDA is dissolved at high temperature. Then, the material is transported to a fixed bed reactor by a high temperature pump, and the material undergoes a hydrogenation reaction on a catalyst. After the hydrogenated liquid is separated by gas and liquid, it is cooled to obtain a CHDM hydrogenated liquid. Gas chromatography is used for quantitative analysis to calculate the CHDA conversion rate and the CHDM yield.

[0141] Specifically: The catalyst evaluation was carried out in a fixed bed reactor, and 10.0 g of catalyst was loaded into a reaction tube with an inner diameter of 20 mm. CHDA was dissolved in an autoclave to obtain a 30 wt % CHDA aqueous solution, which was pumped into the fixed bed by a high temperature pump. Catalyst evaluation conditions: reaction temperature 220°C, reaction pressure 8.0 MPa, CHDA feed mass space velocity 1.0 h -1 , the molar ratio of hydrogen to CHDA is 20.0.

[0142] The catalytic activity evaluation results of catalysts Cat.-3 to Cat.-8 are shown in Table 3.

[0143] Table 3 Catalytic activity of catalysts Cat.-3 to Cat.-8 in CHDA hydrogenation to CHDM

[0144]

[0145] Note: trans = trans isomer / (cis isomer + trans isomer)*100%

[0146] It can be seen from the data in Table 3 that after the activated carbon carrier is treated with nitric acid, the CHDA conversion rate and the product CHDM selectivity are significantly improved. When the percentage concentration of nitric acid treatment is 15%, the catalyst performance is better, the CHDA conversion rate reaches 90.6%, and the CHDM yield is 94.5%; when the percentage concentration of nitric acid treatment is 10%, the CHDA conversion rate is only 86.5%, and the CHDM yield is 92.5%; when the percentage concentration of nitric acid treatment reaches 20%, the CHDA conversion rate is slightly increased compared with 15%, reaching 91.2%, but the CHDM yield drops to 93.5%. Therefore, the more preferred percentage concentration of nitric acid treatment is 15.0%. Comparing the catalytic activities of catalysts Cat.-4, Cat.-7 and Cat.-8, it can be seen that the catalyst performance is best when the nitric acid treatment temperature is 90°C.

[0147] 2.2 Investigating the effect of the first metal promoter M1 on catalyst activity

[0148] The evaluation method of the catalyst is the same as 2.1, the difference is that different catalysts are used, see Table 4 for details.

[0149] Table 4 Catalytic activity of catalysts with different first metal promoters for CHDA hydrogenation to CHDM

[0150]

[0151] Note: The carrier is Carbon-1, the metal Ru loading is 6.0wt%, the metal Sn loading is 5.0wt%, and the metal M1 loading is 1.5wt%

[0152] It can be seen from the data in Table 4 that the addition of the first metal additive M1 can improve the CHDA conversion rate and CHDM selectivity of the catalyst, especially Pt and Rh. Considering that Rh is expensive, Pt is preferably used as the first additive in practical applications to reduce production costs.

[0153] 2.3 Investigating the effect of metal loading on catalyst activity

[0154] The evaluation method of the catalyst is the same as 2.1, the difference is that different catalysts are used, see Table 5 for details.

[0155] Table 5 Catalytic activity of catalysts with different metal loadings in CHDA hydrogenation to CHDM

[0156]

[0157]

[0158] It should be noted that: the carrier used by Cat.-9 is columnar activated carbon, and the others are flake activated carbon; Cat.-1 uses untreated flake activated carbon carrier; the loading amount of catalyst Cat.-14 is 20.0g, and the loading amount of catalyst Cat.-15 is 40.0g, that is, the total metal loading is ensured to be the same; trans = trans isomer / (cis isomer + trans isomer)*100%.

[0159] Comparing the catalytic activities of catalysts Cat.-1 and Cat.-2 in Table 5, it can be seen that after the carrier activated carbon is pretreated with nitric acid, the CHDA conversion rate and CHDM selectivity can be improved. Comparing the catalytic activities of catalysts Cat.-4 and Cat.-9, it can be seen that the catalyst performance is equivalent after the columnar activated carbon or the sheet activated carbon is treated with nitric acid. Comparing the catalytic activities of catalysts Cat.-2, Cat.-4, Cat.-14 and Cat.-15, it can be seen that the addition of the auxiliary agent Pt can improve the CHDA conversion rate and CHDM selectivity. When the theoretical loading amount of Ru metal is 6.0wt% and the theoretical loading amount of Sn is 4.0~5wt%, the catalyst performance is optimal when the addition amount of the auxiliary agent Pt is 1.5wt%. Comparison of the catalytic activities of the catalysts Cat.-4, Cat.-12 and Cat.-13 shows that when the second metal Sn content is 4.0wt%, the CHDA conversion rate is high, but the CHDM yield is relatively low. When the second metal Sn content reaches 6.0wt%, although the CHDM yield is increased to 95.8%, the CHDA conversion rate drops to 86.9%. The theoretical loading of the second metal Sn is preferably 5wt%. Comparison of the catalytic activities of the catalysts Cat.-4, Cat.-16 and Cat.-17 shows that when the total metal loading decreases, the CHDA conversion rate and CHDM selectivity decrease instead. The main reason is that the generated product CHDM, intermediates and raw material CHDA will undergo esterification reaction. After the loading is reduced, the raw material CHDA cannot be converted into the product CHDM in time, and esterification side reactions are more likely to occur.

[0160] 2.4 Investigating the effects of the second metal promoter and reduction temperature on catalyst activity

[0161] The evaluation method of the catalyst is the same as 2.1, the difference is that different catalysts are used, see Table 6 for details.

[0162] Table 6 investigates the effects of the second additive metal and reduction temperature

[0163]

[0164]

[0165] Note: trans = trans isomer / (cis isomer + trans isomer)*100%

[0166] Comparing the catalytic activity data of catalysts Cat.-4 and Cat.-8 to Cat.-20, it can be seen that the addition of the second auxiliary metal Mn, W, and Co can improve the conversion rate of CHDA and the selectivity of the product CHDM. The possible reason is that the addition of the second auxiliary metal reduces the size of the metal particles.

[0167] Examples B20-B22 investigated the loading amount of the auxiliary agent Co. When the loading amount of Co was 1wt%, the catalyst performance was the best. Comparing the catalytic activity data of Examples B20, B23 and B24, it can be seen that the catalyst reduction temperature is best at 400°C, and the catalyst reaction performance is slightly worse at a reduction temperature of 300°C. When the reduction temperature is 500°C, the CHDA conversion rate drops to 95.4%, which may be due to the fact that the catalyst agglomerates during high-temperature reduction.

[0168] 3. Optimization of reaction conditions

[0169] The reaction process conditions were optimized in a fixed bed reactor, and 10.0 g of the catalyst Cat.-20 was loaded in a reaction tube with an inner diameter of 20 mm. CHDA was dissolved in a high-pressure dissolving kettle to obtain a 30 wt% CHDA aqueous solution, and the CHDA solution was pumped into the fixed bed by a high-temperature pump, and hydrogen was introduced for reaction. Among them, the hydrogenation reaction conditions corresponding to Example C1 were: reaction pressure 8.0 MPa, CHDA feed mass space velocity 1.0 h-1, hydrogen to CHDA molar ratio of 20.0, reaction temperature 220°C; Examples C2 to C9 changed the corresponding hydrogenation reaction conditions, and the results are shown in Table 7.

[0170] Table 7 Effect of reaction conditions on the hydrogenation performance of 1,4-cyclohexanedicarboxylic acid

[0171]

[0172]

[0173] Note: trans = trans isomer / (cis isomer + trans isomer)*100%

[0174] Comparing the experimental data of Examples C1 to C3 in Table 7, it can be seen that the CHDA feed space velocity is ≤1.0h -1 When the CHDA feed space velocity reaches 1.2h -1, the CHDA conversion rate dropped to 97.9%. Comparing the data of Examples C1, C4 and C5, it can be seen that the reaction temperature of the catalyst hydrogenation is 220°C, and the reaction effect is better. When the reaction temperature is as low as 210°C, some CHDA and intermediates are not completely converted, and the reaction is not thorough, so the hydrogenation effect is poor; and when the reaction temperature is increased to 230°C, the by-product ester content begins to increase. Comparing the experimental data of Examples C1, C6 and C7, it can be seen that the hydrogenation pressure is 8.0MPa, the hydrogenation effect is better, the CHDA conversion rate is 99.8%, and the CHDM yield is 98.9%. Comparing Examples C1, C8 and C9, it can be seen that the H2 / CHDA molar ratio is preferably 20.

[0175] Comparison of the experimental data of Examples C1, C4 and C5 shows that, under the same CHDA feed space velocity, H2 / CHDA molar ratio and reaction pressure, as the reaction temperature increases, the trans isomer ratio in the hydrogenated liquid increases (from 69.5% to 76.5%); Comparison of the experimental data of Examples C1, C2 and C3 shows that, under the same H2 / CHDA molar ratio, reaction pressure and reaction temperature, the trans isomer ratio decreases as the CHDA feed space velocity increases; Comparison of the experimental data of Examples C1, C6 and C7 shows that, under the same CHDA feed space velocity, H2 / CHDA molar ratio and reaction temperature, the trans isomer ratio increases as the reaction pressure increases, but the increase is not obvious; Comparison of the experimental data of Examples C1, C8 and C9 shows that, under the same CHDA feed space velocity, reaction temperature and reaction pressure, the trans isomer ratio increases as the H2 / CHDA molar ratio increases.

[0176] That is, in the present invention, trans-1,4-cyclohexanedimethanol in the hydrogenated liquid is positively correlated with the reaction temperature, H2 / CHDA molar ratio and reaction pressure, and is negatively correlated with the PTA feed space velocity. In the reaction of preparing 1,4-cyclohexanedimethanol by hydrogenating 1,4-cyclohexanedicarboxylic acid under the catalyst provided by the present invention, the yield of trans-1,4-cyclohexanedimethanol can be adjusted by controlling the preset hydrogenation reaction conditions.

[0177] 4. Catalyst life evaluation

[0178] According to the hydrogenation reaction conditions of Example C1, the life of the catalysts Cat.-4 and Cat.-20 was evaluated. The results are shown in Figure 1 .

[0179] Depend on Figure 1The data show that the initial CHDA conversion rate of catalyst Cat.-4 is 90.6%, and the CHDM selectivity is 94.5%. In the first 500 hours of evaluation, the CHDA conversion rate and CHDM selectivity remain basically stable. After 500 hours, the CHDA conversion rate and CHDM selectivity gradually decrease. By 1000 hours, the CHDA conversion rate dropped to ~80%, and the CHDM selectivity dropped to ~90%. Catalyst Cat.-20 has good stability. After 3000 hours, the CHDA conversion rate is still maintained at 99.5%, and the CHDM selectivity is as high as 98.5%. The catalyst has good industrial application prospects for CHDA hydrogenation to CHDM. The above experimental results show that the introduction of the second auxiliary agent Co not only improves the activity of the catalyst, but also makes the obtained metal alloy particles more stable, and it is possible to inhibit the adhesion of Ni, Fe ions (stainless steel reactor corrosion) on the surface of the metal alloy, so that the catalyst stability is greatly improved.

[0180] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid, characterized in that: Under specific catalysts and preset reaction conditions, 1,4-cyclohexanedicarboxylic acid aqueous solution reacts with hydrogen to generate hydrogenated liquid including 1,4-cyclohexanedimethanol, wherein the preset reaction conditions include: a reaction temperature of 210 to 230° C., a reaction pressure of 6 MPa to 12 MPa, and the catalyst includes: The first metal Ru, based on the total weight of the catalyst as 100%, the theoretical loading amount of the first metal Ru is 1 to 9 wt%; The second metal Sn, based on the total weight of the catalyst as 100%, the theoretical loading amount of the second metal Sn is 1 to 10 wt%; A first auxiliary metal M1, wherein the metal M1 is selected from one of Pd, Pt and Rh, and the theoretical loading amount of the metal M1 is 0.1-3.0 wt% based on the total weight of the catalyst as 100%; A second promoter metal M2, wherein the metal M2 is selected from one of Co, Mn and W, and the theoretical loading amount of the metal M2 is 0.05-5.0 wt% based on the total weight of the catalyst as 100%; Carrier C is pretreated activated carbon, and the total weight of the first metal Ru, the second metal Sn, the first auxiliary metal M1, the second auxiliary metal M2 and the carrier is 100%.

2. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to claim 1, characterized in that: The catalyst is one of Ru-Sn-Pt-Co / C, Ru-Sn-Pt-Mn / C and Ru-Sn-Pt-W / C.

3. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to claim 1, characterized in that: The catalyst is one of Ru-Sn-Pd-Co / C, Ru-Sn-Pd-Mn / C and Ru-Sn-Pd-W / C.

4. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to claim 1, characterized in that: The catalyst is one of Ru-Sn-Rh-Co / C, Ru-Sn-Rh-Mn / C and Ru-Sn-Rh-W / C.

5. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to any one of claims 1 to 4, characterized in that: Taking the total weight of the catalyst as 100%, the total loading amount of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 in the catalyst is 10wt~15wt%, and the mass ratio of the first metal Ru, the second metal Sn, the first auxiliary metal M1 and the second auxiliary metal M2 is: 6:(4~5):1.5:(0.5~1.5).

6. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to any one of claims 1 to 4, characterized in that: The pretreatment of the activated carbon is: placing the activated carbon in a nitric acid solution for acid treatment to introduce oxygen-containing groups including carboxyl groups on the surface of the activated carbon, and the acid treatment conditions include: a treatment temperature of 60 to 95° C. and a treatment time of 0.5 to 8 hours. Preferably, the treatment temperature is 90 to 95° C.

7. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to claim 6, characterized in that: The mass ratio of the activated carbon to the nitric acid solution is 1:(2-10), and the mass percentage concentration of the nitric acid solution is 10-20%. Preferably, the mass percentage concentration of the nitric acid solution is 15%.

8. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to any one of claims 1 to 4, characterized in that: The preparation method of the catalyst comprises: firstly preparing a catalyst precursor by an equal volume impregnation method, and then reducing the catalyst precursor with a reducing agent to obtain the catalyst, wherein the reducing agent is hydrogen, and the conditions of the reduction treatment include: 150-500°C, preferably 300-400°C; hydrogen volume space velocity 50-500h -1 , preferably 100 to 200 hours -1 .

9. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to any one of claims 1 to 4, characterized in that: The preset reaction conditions also include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.05 to 2.0 h -1 The molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 5.0 to 80.0; preferably, the preset reaction conditions include: the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid is 0.8 to 1.2 h -1 , the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid is 10-30, the reaction temperature is 220°C, and the reaction pressure is 8MPa-9MPa.

10. The method for preparing 1,4-cyclohexanedimethanol by continuous hydrogenation of 1,4-cyclohexanedicarboxylic acid according to claim 9, characterized in that: During the hydrogenation reaction, the yield of trans-1,4-cyclohexanedimethanol in the hydrogenated liquid can be adjusted by controlling the reaction temperature, the molar ratio of hydrogen to 1,4-cyclohexanedicarboxylic acid, and the feed mass space velocity of 1,4-cyclohexanedicarboxylic acid.

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