Catalyst for synthesizing cyclohexanedimethanol through catalytic hydrogenation of crude terephthalic acid and preparation method thereof

Abstract

The invention belongs to the field of chemical synthesis, and particularly relates to a catalyst for synthesizing cyclohexanedimethanol through catalytic hydrogenation of crude terephthalic acid and a preparation method. According to the catalyst, activated carbon is used as a carrier, and supported molybdenum nitride (MoN-AC) with a high specific surface area is prepared. And loading a metal active component on the surface of the MoN-AC catalyst, and activating to obtain the M / MoN-AC catalyst. Crude PTA containing p-carboxybenzaldehyde is used as a raw material, the prepared M / MoN-AC is used as a catalyst, a hydrogenation reaction is carried out in a proper solvent by controlling proper temperature and hydrogen pressure, and CHDM is efficiently synthesized. According to the CuRu / MoN-AC catalyst prepared by the invention, CuRu and MoN have a synergistic catalysis effect, and the N element in MoN has dispersion and stabilization effects on the CuRu active component, so that the catalyst disclosed by the invention has a high catalytic effect and better stability, and is very beneficial to industrial application.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, specifically relating to a catalyst and its preparation method for the catalytic hydrogenation of crude terephthalic acid to synthesize cyclohexanediol. Background Technology

[0002] 1,4-Cyclohexanediethanol (CHDM) is an important chemical raw material and a key monomer for the production of high-melting-point, high-quality, and high-impact polyester products. It is also an intermediate for coatings, inks, adhesives, insulating materials, and some special-purpose unsaturated polyesters. Therefore, CHDM has a huge market demand.

[0003] The main methods for preparing CHDM are:

[0004] 1. Catalytic hydrogenation of terephthalate: CN116444343 proposes a two-stage catalytic hydrogenation technology. In the first stage, Ru / TiO2 is used to catalyze the hydrogenation of PET to produce ethylene glycol cyclohexanedicarboxylate. In the second stage, Cu / Mn3O4-Al2O3 is used to catalyze the hydrogenation to further produce CHDM, with a yield of 100%. CN120571586 proposes a one-step catalytic hydrogenation method using NiCu / SiO2 to synthesize CHDM from dimethyl terephthalate, with a yield of 93%.

[0005] 2. Catalytic hydrogenation of commercial terephthalic acid (PTA): CN117816154 proposes a method using a RuPd / C and CuZn / C composite catalyst to convert commercial PTA to CHDM in two stages at 2.5 MPa H2 and 170℃, and 230℃ and 8.0 MPa H2, respectively, with a yield of 93.2%. WO 2015156582 further proposes a method using a Pd / C and RuSnPt / C catalyst to catalyze the hydrogenation of commercial PTA to CHDM at 230℃ and 8.0 MPa H2, with a yield of 85%.

[0006] 3. Catalytic hydrogenation of terephthalic acid: CN103878003 proposes using PdPt / NiMoP as a catalyst to hydrogenate terephthalic acid under relatively mild conditions of 100℃ and 1.5 MPa H2 to obtain CHDM with a yield of 96.1%.

[0007] 4. Catalytic hydrogenation of terephthalaldehyde: EP1099475 proposes using Raney Ni as a catalyst to catalyze the hydrogenation of terephthalaldehyde to CHDM at 60℃ and 4.0MPa H2, with a yield of 89%.

[0008] CHDM is a bulk chemical with a market demand of millions of tons, making it highly sensitive to raw material costs. Methods 1, 3, and 4 mentioned above all have high raw material costs, resulting in high product costs and a lack of competitiveness. Method 2 uses commercial PTA as raw material, which has relatively lower costs, but it requires high-quality catalysts, relies on precious metal catalysis, and operates under demanding conditions.

[0009] The mainstream production technology for commercial PTA is as follows: using p-xylene as raw material, Co-Mn-Br as catalyst, and air or oxygen as oxidant, an oxidation reaction is carried out in an acetic acid medium. The oxidation product is centrifuged to obtain solid crude PTA. The crude PTA is then purified by Pd / C hydrogenation, followed by 5-stage crystallization and water washing to obtain refined PTA. The purity of crude PTA is approximately 99.5%, with the main impurity being p-carboxybenzaldehyde (4-CBA). To remove approximately 0.3-0.4% of 4-CBA, in practice, the crude PTA is dissolved in pure water at 286℃ and 7.6 MPa, and then hydrogenated using Pd / C catalysis to convert 4-CBA into p-methylbenzoic acid (see Formula 1). This is then removed by 5-stage crystallization, pressure filtration, and water washing to obtain refined PTA (commercial product) with a purity of 99.98%. As can be seen from the above refining process, the crude PTA refining process is a complex, energy-intensive process that generates a large amount of wastewater and consumes precious metal catalysts, resulting in high operating costs.

[0010]

[0011] Formula 1. Summary of the Invention

[0012] The purpose of this invention is to provide a novel catalytic technology that directly uses crude PTA containing 4-CBA as a raw material, and through catalytic hydrogenation, converts it entirely into the target product CHDM, thereby achieving low-cost production of CHDM. The reaction process is shown in Equation 2.

[0013]

[0014] Formula 2

[0015] To achieve the above objectives, the technical solution adopted in this invention is as follows: High specific surface area supported molybdenum nitride (MoN-AC) is prepared using coconut shell activated carbon (AC) as a carrier. A metal active component (M) is then loaded onto its surface and activated to obtain an M / MoN-AC catalyst. Then, using crude PTA containing 4-CBA as raw material, and the prepared M / MoN-AC as a catalyst, a hydrogenation reaction is carried out in a suitable solvent at a controlled temperature and hydrogen pressure, thereby achieving high-efficiency synthesis of CHDM.

[0016] The method for preparing high specific surface area supported molybdenum nitride (MoN-AC) is as follows: ammonium molybdate [(NH4)6Mo7O] 24[·4H2O] is dissolved in hot water to obtain an ammonium molybdate aqueous solution, which is used to impregnate AC. After impregnation at the hot water temperature for 8-12 h, it is dried at 120℃ for 12 h to obtain the precursor. Subsequently, the precursor is placed in a high-temperature furnace and treated at a certain heating rate in an NH3 atmosphere for a certain time to obtain MoN-AC with a high specific surface area.

[0017] In the preparation of MoN-AC, the amount of ammonium molybdate used is such that the Mo element:AC ratio in MoN-AC is 15~30:100 (by weight), preferably 20~25:100 (by weight); the weight ratio of water to AC is 3~5:1; the dissolution temperature of ammonium molybdate in water is the same as the impregnation temperature, which is 60~90 ℃.

[0018] The programmed heating rate of the precursor in a high-temperature furnace and NH3 atmosphere is 1~5℃ / min, and the preferred programmed heating rate is 1.5~2.5℃ / min; the high-temperature treatment in NH3 atmosphere for a certain period of time refers to the programmed heating to 650~750℃ and maintaining it for 3~6 h.

[0019] The preparation method of M / MoN-AC catalyst is as follows: MoN-AC is impregnated with an aqueous solution of Cu and Ru nitrate or acetate at room temperature for 6-12 h, then dried at 120℃ for 12 h, and activated to obtain catalyst CuRu / MoN-AC.

[0020] The weight ratio of water to AC is 2-4:1, the weight ratio of Cu and Ru to AC is 10-16:100, and the weight ratio of Cu to AC in the Cu-Ru composition is Cu:Ru = 1.0-2.0:1.0, preferably Cu:Ru = 1.25-1.5:1.0 (weight ratio).

[0021] The catalyst activation method involves high-temperature reduction with hydrogen to obtain CuRu / MoN-AC. The hydrogen high-temperature reduction activation method uses a mixture of H2 and N2 in a volume ratio of H2:N2 = 1~4:10. The temperature is increased at a rate of 2~5℃ / min to a suitable high-temperature reduction time. A suitable high-temperature reduction time refers to 250~400℃ for 2~5 hours.

[0022] Suitable solvents for the hydrogenation of crude PTA catalyzed by CuRu / MoN-AC can be methanol, ethanol, isopropanol, etc., or ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol dimethyl ether, etc. A suitable solvent ratio is: solvent: crude PTA = 4~8:1 (by weight).

[0023] The suitable dosage of the hydrogenation catalyst CuRu / MoN-AC is: catalyst: crude PTA = 5~15:100 (weight ratio). The suitable conditions for the hydrogenation of crude PTA catalyzed by CuRu / MoN-AC are: 220~260 ℃, 6.0~10.0 MPa H2, preferably 230~250 ℃, 7~8 MPa H2. The hydrogenation reaction time is determined based on the sampling analysis during the reaction process; the suitable reaction time is when the CHDM content in the sample is the highest. Quantitative analysis is performed using high performance liquid chromatography (HPLC).

[0024] Effects of the present invention

[0025] (1) In this invention, crude PTA is used instead of commercial PTA, and CHDM is synthesized by hydrogenation under CuRu / MoN-AC catalysis. This avoids the cost of converting impurity 4-CBA into useless p-methylbenzoic acid in the traditional process, and has a significant cost advantage.

[0026] (2) High specific surface area AC is readily prepared by impregnating ammonium molybdate with AC. Since MoN has good tolerance to halogens (such as Cl and Br), sulfur and nitrogen compounds, the CuRu / MoN-AC catalyst prepared based on MoN in this invention can be applied to the catalytic hydrogenation of crude PTA containing trace amounts of bromine compounds.

[0027] (3) By loading CuRu active components with MoN-AC with high specific surface area, the catalyst CuRu / MoN-AC prepared in this invention has the advantages of simplified operation process and low cost.

[0028] (4) The presence of N element in the MoN-AC carrier of the present invention makes the catalyst have strong adsorption of crude PTA and weak adsorption of product CHDM, thus facilitating the high-selectivity generation of CHDM.

[0029] (5) The CuRu / MoN-AC catalyst prepared by the present invention has a synergistic catalytic effect between CuRu and MoN. In addition, the N element in MoN has a dispersing and stabilizing effect on the CuRu active component, which makes the catalyst proposed by the present invention have high catalytic effect and better stability, which is very beneficial to industrial application. Attached Figure Description

[0030] Figure 1 The liquid nitrogen adsorption-desorption analysis curve is shown for the catalyst prepared in Example 1.

[0031] Figure 2 The liquid nitrogen adsorption-desorption analysis curve is shown for the catalyst prepared in Example 5.

[0032] Figure 3Scanning electron microscope (SEM) image of the surface microstructure and surface elemental distribution (EDS) of the catalyst prepared in Example 5. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments.

[0034] Example 1

[0035] Catalyst preparation: 27.6 g of ammonium molybdate (containing 54.3% Mo) and 300 g of water were dissolved by heating to 60 °C. Then, 100 g of coconut shell activated carbon [commercial coconut shell activated carbon (AC) has a specific surface area of ​​1080 m² / g, a pore volume of 1.18 mL / g, and an average pore size of 4.4 nm] was added. The mixture was impregnated at 60 °C for 8 h, then dried at 120 °C for 12 h. The dried material was placed in a high-temperature furnace, ammonia gas was introduced, and the temperature was increased to 650 °C at a rate of 5 °C / min, and maintained at this temperature for 6 h. Subsequently, it was cooled to room temperature in an ammonia atmosphere and removed to obtain MoN-AC. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​974 m² / g, a pore volume of 0.88 mL / g, and an average pore size of 3.6 nm.

[0036] 15.7 g of copper acetate (containing 31.8% Cu) and 13.8 g of ruthenium acetate (containing 36.3% Ru) were dissolved in 200 g of water to obtain an active component impregnation solution. The prepared MoN-AC was added to this solution and impregnated at room temperature for 6 h, followed by drying at 120 °C for 12 h. Subsequently, it was placed in a tube furnace and heated to 250 °C at a heating rate of 2 °C / min in a mixed atmosphere of H2:N2 = 1:10 (volume ratio), and maintained at this temperature for 5 h. It was then cooled to room temperature in this atmosphere, removed, and stored in tetrahydrofuran for later use. This yielded CuRu / MoN-AC, named C-1#. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​783 m² / g, a pore volume of 0.63 mL / g, and an average pore size of 3.2 nm (see [link to liquid nitrogen adsorption-desorption analysis]). Figure 1 ).

[0037] Crude PTA catalytic hydrogenation to CHDM:

[0038] 200g methanol, 2.5g C-1#, and 25g crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical, obtained by centrifugation, washing with water, and drying; its weight composition was 99.63% PTA, 0.32% 4-CBA, with the remainder being trace impurities introduced from the oxidation reaction system) were added to a 500mL stainless steel autoclave. The reaction was carried out at 220℃ and 10MPa H2 for 16 h, resulting in complete conversion of the raw materials and a CHDM yield of 90.5%.

[0039] Example 2

[0040] Catalyst preparation: 36.8 g of ammonium molybdate (containing 54.3% Mo) and 400 g of water were dissolved by heating to 70 °C. Then, 100 g of coconut shell activated carbon (commercial coconut shell activated carbon (AC) with a specific surface area of ​​1080 m² / g, pore volume of 1.18 mL / g, and average pore size of 4.4 nm) was added. The mixture was impregnated at 70 °C for 10 h, then dried at 120 °C for 12 h. The dried material was placed in a high-temperature furnace, ammonia gas was introduced, and the temperature was increased to 700 °C at a rate of 3.5 °C / min, and maintained at this temperature for 5 h. Subsequently, it was cooled to room temperature in an ammonia atmosphere and removed to obtain MoN-AC. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​958 m² / g, a pore volume of 0.79 mL / g, and an average pore size of 2.0 nm.

[0041] 21.0 g of copper acetate (containing 31.8% Cu) and 14.7 g of ruthenium acetate (containing 36.3% Ru) were dissolved in 300 g of water to obtain an active component impregnation solution. The prepared MoN-AC was added to this solution and impregnated at room temperature for 8 h, followed by drying at 120 °C for 12 h. Subsequently, it was placed in a tube furnace and heated to 350 °C at a heating rate of 3 °C / min in a mixed atmosphere of H2:N2 = 1:5 (volume ratio), and maintained at this temperature for 4 h. It was then cooled to room temperature in this atmosphere, removed, and stored in tetrahydrofuran for later use, thus obtaining CuRu / MoN-AC, named C-2#. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​752 m² / g, a pore volume of 0.58 mL / g, and an average pore size of 3.1 nm.

[0042] Crude PTA catalytic hydrogenation to CHDM:

[0043] 150 g of ethanol, 3.75 g of C-2#, and 25 g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical, obtained by centrifugation, washing with water, and drying; its weight composition was 99.63% PTA, 0.32% 4-CBA, and the remainder being trace impurities introduced from the oxidation reaction system) were added to a 500 mL stainless steel autoclave. The reaction was carried out at 230 °C and 6.0 MPa H2 for 16 h, resulting in complete conversion of the feedstock and a CHDM yield of 93.8%.

[0044] Example 3

[0045] Catalyst preparation: 46.0 g of ammonium molybdate (containing 54.3% Mo) and 500 g of water were dissolved by heating to 80 °C. Then, 100 g of coconut shell activated carbon (commercial coconut shell activated carbon (AC) with a specific surface area of ​​1080 m² / g, pore volume of 1.18 mL / g, and average pore size of 4.4 nm) was added. The mixture was impregnated at 80 °C for 12 h, then dried at 120 °C for 12 h. The dried material was placed in a high-temperature furnace, ammonia gas was introduced, and the temperature was increased to 750 °C at a rate of 2.5 °C / min, and maintained at this temperature for 4 h. Subsequently, it was cooled to room temperature in an ammonia atmosphere and removed to obtain MoN-AC. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​916 m² / g, a pore volume of 0.71 mL / g, and an average pore size of 3.1 nm.

[0046] 26.4 g of copper acetate (containing 31.8% Cu) and 15.4 g of ruthenium acetate (containing 36.3% Ru) were dissolved in 400 g of water to obtain an active component impregnation solution. The prepared MoN-AC was added to this solution and impregnated at room temperature for 10 h, followed by drying at 120 °C for 12 h. The solution was then placed in a tube furnace and heated to 400 °C at a rate of 5 °C / min in a mixed atmosphere of H2:N2 = 3:10 (volume ratio), and maintained at this temperature for 2 h. The solution was then cooled to room temperature in this atmosphere, removed, and stored in tetrahydrofuran for later use, thus obtaining CuRu / MoN-AC, named C-3#. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​704 m² / g, a pore volume of 0.53 mL / g, and an average pore size of 3.0 nm.

[0047] Crude PTA catalytic hydrogenation to CHDM:

[0048] 150g of ethylene glycol methyl ether, 3.0g of C-3#, and 30g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical by centrifugation and washing with water, with a weight composition of 99.63% PTA and 0.32% 4-CBA) were added to a 500mL stainless steel autoclave. The reaction was carried out at 240℃ and 8.0 MPa H2 for 14h, and the raw materials were completely converted, with a CHDM yield of 95.6%.

[0049] Example 4

[0050] Catalyst preparation: 55.3 g of ammonium molybdate (containing 54.3% Mo) and 500 g of water were dissolved by heating to 90 °C. Then, 100 g of coconut shell activated carbon (commercial coconut shell activated carbon (AC) with a specific surface area of ​​1080 m² / g, pore volume of 1.18 mL / g, and average pore size of 4.4 nm) was added. The mixture was impregnated at 90 °C for 12 h, then dried at 120 °C for 12 h. The dried material was placed in a high-temperature furnace, ammonia gas was introduced, and the temperature was increased to 750 °C at a rate of 1.5 °C / min, and maintained at this temperature for 3 h. Subsequently, it was cooled to room temperature in an ammonia atmosphere and removed to obtain MoN-AC. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​836 m² / g, a pore volume of 0.59 mL / g, and an average pore size of 2.8 nm.

[0051] 40.7 g of copper nitrate (containing 26.2% Cu) and 16.8 g of ruthenium nitrate (containing 31.8% Ru) were dissolved in 400 g of water to obtain an active component impregnation solution. The prepared MoN-AC was added to this solution and impregnated at room temperature for 12 h. Then, it was dried at 120 °C for 12 h, and subsequently placed in a tube furnace. The temperature was increased to 250 °C at a rate of 2 °C / min in a mixed atmosphere of H2:N2 = 2:5 (volume ratio), and maintained at this temperature for 5 h. It was then cooled to room temperature in this atmosphere, removed, and stored in tetrahydrofuran for later use, thus obtaining CuRu / MoN-AC, named C-4#. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​688 m² / g, a pore volume of 0.45 mL / g, and an average pore size of 2.6 nm.

[0052] Crude PTA catalytic hydrogenation to CHDM:

[0053] 100g of ethylene glycol dimethyl ether, 1.25g of C-4#, and 25g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical by centrifugation and washing with water, with a weight composition of 99.63% PTA and 0.32% 4-CBA) were added to a 500mL stainless steel autoclave. The reaction was carried out at 250℃ and 7.0 MPa H2 for 18h, and the raw materials were completely converted, with a CHDM yield of 94.4%.

[0054] Example 5

[0055] Catalyst preparation: 46.0 g of ammonium molybdate (containing 54.3% Mo) and 300 g of water were dissolved by heating to 90 °C, and then 100 g of coconut shell activated carbon (commercial coconut shell activated carbon (AC) with a specific surface area of ​​1080 m² / g and a pore volume of 1.18 mL / g) was added. The mixture was impregnated at 90 °C for 12 h, and then dried at 120 °C for 12 h. The dried material was placed in a high-temperature furnace, ammonia gas was introduced, and the temperature was increased to 700 °C at a rate of 1.0 °C / min, and maintained at this temperature for 4 h. Subsequently, it was cooled to room temperature in an ammonia atmosphere and removed to obtain MoN-AC. Liquid nitrogen adsorption-desorption analysis showed that its specific surface area was 819 m² / g, pore volume was 0.66 mL / g, and average pore size was 3.2 nm.

[0056] 36.7 g of copper nitrate (containing 26.2% Cu) and 20.2 g of ruthenium nitrate (containing 31.8% Ru) were dissolved in 300 g of water to obtain an active component impregnation solution. The prepared MoN-AC was added to this solution and impregnated at room temperature for 12 h, followed by drying at 120 °C for 12 h. Subsequently, it was placed in a tube furnace and heated to 250 °C at a heating rate of 2 °C / min in a mixed atmosphere of H2:N2 = 1:5 (volume ratio), and maintained at this temperature for 4 h. It was then cooled to room temperature in this atmosphere, removed, and stored in tetrahydrofuran for later use. This yielded CuRu / MoN-AC, named C-5#. Liquid nitrogen adsorption-desorption analysis showed a specific surface area of ​​710 m² / g, a pore volume of 0.57 mL / g, and an average pore size of 3.2 nm (see [link to liquid nitrogen adsorption-desorption analysis]). Figure 2 ).

[0057] Scanning electron microscopy (SEM) images of the catalyst surface morphology and elemental distribution (EDS) are shown below. Figure 3 .

[0058] Crude PTA catalytic hydrogenation to CHDM:

[0059] 200g of ethylene glycol ethyl ether, 4.0g of C-5#, and 25g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical, obtained by centrifugation, washing with water, and drying; its weight composition was 99.63% PTA, 0.32% 4-CBA, and the remainder being trace impurities introduced from the oxidation reaction system) were added to a 500mL stainless steel autoclave. The reaction was carried out at 260℃ and 8.0MPa H2 for 13 h, and the feedstock was completely converted, with a CHDM yield of 95.6%.

[0060] Example 6

[0061] The conditions for the catalytic hydrogenation of crude PTA to CHDM were modified using catalyst C-5#.

[0062] 200g of ethylene glycol ethyl ether, 3.75g of C-5#, and 25g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical, centrifuged and washed with water to obtain crude PTA, with a weight composition of 99.63% PTA and 0.32% 4-CBA) were added to a 500mL stainless steel autoclave. The reaction was carried out at 250℃ and 8.0 MPa H2 for 11.5h, and the raw materials were completely converted, with a CHDM yield of 98.4%.

[0063] Example 7

[0064] Evaluation of the recycling effect of C-5# catalyst.

[0065] Crude PTA catalytic hydrogenation to CHDM:

[0066] 500g of ethylene glycol ethyl ether, 10.0g of C-5#, and 100g of crude PTA (obtained from the reaction liquid in the PTA unit of Yangzi Petrochemical by centrifugation and washing with water, with a weight composition of 99.63% PTA and 0.32% 4-CBA) were added to a 1000mL stainless steel autoclave. The reaction was carried out at 250℃ and 8.0MPa H2 for 13h, and the raw materials were completely converted, with a CHDM yield of 98.7%.

[0067] After the reaction was completed, the reactor was cooled to 80°C, depressurized, and discharged. The solid catalyst was recovered by hot filtration and used directly in the next reaction. The filtrate was distilled at 100–140°C to remove the solvent and volatiles. Residual solids were sampled and their composition was analyzed by high-performance liquid chromatography (HPLC) to calculate the CHDM yield. The catalyst usage results are listed in Table 1.

[0068] Table 1. Results of recycling of C-5# catalyst for the hydrogenation of crude PTA to CHDM

[0069] Number of times used 1 2 3 4 5 6 7 8 9 10 Reaction time, h 13 13 12.5 13.5 14 14 14 14.5 15 15.5 CHDM yield, % 98.7 98.2 97.8 97.4 98.1 95.9 96.7 96.5 95.6 95.1

[0070] Compare with Example 1

[0071] Following the method in Example 1 of Chinese Invention Patent CN117816154A, 0.5%Pd-5%Ru / C and 10%Cu-1%Zn / C were prepared.

[0072] 500g of ethylene glycol ethyl ether, 100g of crude PTA, 3.0g of Pd-Ru / C, and 9.0g of Cu-Zn / C catalyst were added to a 1000mL stainless steel autoclave. The reaction was carried out at 170℃ and 2.5MPa H2 for 3 hours, followed by a further reaction at 230℃ and 8MPa H2 for 14 hours. The crude PTA was completely converted, and the CHDM yield was 88.9% (total reaction time is marked as 3+14). (Note that in CN117816154, no solvent was added to the reaction system. According to professional knowledge, PTA is solid at 230℃, and the catalyst is also solid, so hydrogenation is impossible).

[0073] After the reaction, the reactor was cooled to 80°C, depressurized, and discharged. The solid catalyst was recovered by hot filtration and used directly in the next reaction. The filtrate was distilled at 100–140°C to remove the solvent and volatiles. Residual solids were sampled and their composition analyzed by high-performance liquid chromatography (HPLC) to calculate the CHDM yield. The catalyst usage results are listed in Table 2.

[0074] Table 2 Results of CHDM recycling via hydrogenation of crude PTA catalyzed by 0.5%Pd-5%Ru / C and 10%Cu-1%Zn / C.

[0075] Number of times used 1 2 3 4 5 6 7 8 9 10 Reaction time, h 3+14 3+15 3+15 4+15 4+15 4+16 5+16 5+16 5+17 5+17 CHDM yield, % 97.5 94.8 94.1 93.2 92.6 91.9 91.1 90.5 88.6 82.1

Claims

1. A method for preparing an M / MoN-AC catalyst, characterized in that, The preparation method is as follows: using activated carbon as a support, a supported molybdenum nitride (MoN-AC) with high specific surface area is prepared, and then the metal active component is loaded onto its surface and activated to obtain the M / MoN-AC catalyst.

2. The method for preparing the M / MoN-AC catalyst according to claim 1, characterized in that, The preparation method of supported molybdenum nitride MoN-AC is as follows: ammonium molybdate [(NH4)6Mo7O] is used. 24 [·4H2O] is dissolved in hot water to obtain an aqueous solution of ammonium molybdate. After impregnation of AC with this solution, it is dried at 120℃ for 12 h to obtain a precursor. Subsequently, the precursor is placed in a high-temperature furnace and treated at high temperature in an NH3 atmosphere to obtain MoN-AC with a high specific surface area.

3. The method for preparing the M / MoN-AC catalyst according to claim 2, characterized in that, The amount of ammonium molybdate used is such that the mass ratio of elemental Mo to AC in MoN-AC is 15~30:100; the weight ratio of water to AC is 3~5:1; the dissolution temperature and impregnation temperature of ammonium molybdate in water are both 60~90 ℃, and the impregnation time is 8~12 h.

4. The method for preparing the M / MoN-AC catalyst according to claim 2, characterized in that, The precursor was placed in a high-temperature furnace and subjected to high-temperature treatment in an NH3 atmosphere, with the temperature increased to 650-750°C at a rate of 1-5°C / minute, for 3-6 hours.

5. The method for preparing the M / MoN-AC catalyst according to claim 1, characterized in that, The method for obtaining the M / MoN-AC catalyst is as follows: MoN-AC is impregnated with an aqueous solution of Cu and Ru nitrates or acetates, then dried at 120℃ for 12 h, and activated by high-temperature reduction with hydrogen to obtain the catalyst CuRu / MoN-AC.

6. The method for preparing the M / MoN-AC catalyst according to claim 5, characterized in that, The mass ratio of water to AC used for impregnating MoN-AC is 2~4:1, the total weight ratio of Cu and Ru to AC is 10~16:100, and the weight ratio of Cu to Ru is 1.0~2.0:1.

0.

7. The method for preparing the M / MoN-AC catalyst according to claim 5, characterized in that, Impregnation is performed at room temperature for 6-12 hours; the method of high-temperature reduction and activation with hydrogen is to use a mixture of H2 and N2 with a volume ratio of 1-4:10, and heat to 250-400℃ at a rate of 2-5℃ / minute, and reduce for 2-5 hours.

8. An M / MoN-AC catalyst prepared by the method according to any one of claims 1-7.

9. An application of an M / MoN-AC catalyst prepared according to any one of claims 1-7, characterized in that, The M / MoN-AC catalyst is used for the catalytic hydrogenation of crude terephthalic acid to synthesize cyclohexanediol in a solvent.

10. The application of the M / MoN-AC catalyst according to claim 9, characterized in that, The solvent is methanol, ethanol, isopropanol, or ethylene glycol methyl ether, ethylene glycol ethyl ether, or ethylene glycol dimethyl ether; the mass ratio of solvent to crude PTA is 4~8:1; the mass ratio of catalyst CuRu / MoN-AC to crude PTA is 5~15:100; the hydrogenation conditions are 220~260 ℃, 6.0~10.0 MPa H2.

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