Composite catalyst and method for preparing dimethyl 1, 4-cyclohexane dicarboxylate through dimethyl terephthalate hydrogenation

Abstract

The invention provides a composite catalyst and a method for preparing dimethyl 1, 4-cyclohexanedicarboxylate through dimethyl terephthalate hydrogenation by using the composite catalyst, and the composite catalyst adopts a composite carrier to load Ru and Zn active metals, the composite carrier is obtained by carrying out crystallization reaction on a hydrochloric acid solution of P123 and tetraethoxysilane, and then mixing with an aluminum source and a USY molecular sieve to carry out hydrothermal reaction. The metal Ru and Zn introduced in the preparation process of the catalyst easily form a Ru-Zn alloy, the formation of the alloy changes the electronic structure on the surface of the catalyst, so that the catalyst can be more effectively coordinated with reactants, the catalytic activity is improved, and the metal Al active sites and many specific functional groups on the composite carrier serve as L acid sites, so that the catalytic activity of the catalyst is improved. The deep hydrogenation is promoted to obtain the effective product 1, 4-cyclohexanedimethanol, and the next ester hydrogenation reaction is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of catalysts and benzene hydrogenation technology, specifically relating to a method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation of dimethyl terephthalate, and the composite catalyst involved. Background Technology

[0002] Dimethyl 1,4-cyclohexanedicarboxylate is an intermediate in the preparation of 1,4-cyclohexanediethanol. Saturated polyesters synthesized from 1,4-cyclohexanediethanol exhibit several superior properties when used in glazes, coatings, and paints. Firstly, the high symmetry of 1,4-cyclohexanediethanol results in a tightly packed polymer chain. This symmetry and tight arrangement facilitates the formation of hydrogen bonds between polymer chains, thereby restricting polymer movement and increasing polymer hardness. Simultaneously, the "chair-like" or "cage-like" structure of the para-substituted cyclohexane ring provides flexibility to the coating. Furthermore, the high symmetry of 1,4-cyclohexanediethanol also enhances the crystallinity of the polyester resin, improving the stability and sintering resistance of powder coatings.

[0003] 1,4-Cyclohexanediethanol can be processed into polyesters such as PETG and PCTG, possessing advantages such as high transparency, good gloss, high strength, high toughness, chemical resistance, and excellent processability. It is widely used in medical devices, electrical appliances, baby products, and high-end decorative materials, and has strong irreplaceable properties. 1,4-Cyclohexanediethanol can also be used to produce high-quality laminating and injection molding resins, widely used in the production of resins for electronic products and insulating wires, exhibiting high electrical resistance and good corrosion resistance. The most important application of 1,4-Cyclohexanediethanol is in the preparation of linear polyester fibers. Due to the relatively low density, high melting point, and good electrical properties of fibers made from this raw material, it is particularly suitable for manufacturing electrical equipment.

[0004] As an intermediate in the preparation of 1,4-cyclohexanedimethyl methanol, dimethyl 1,4-cyclohexanedicarboxylate is prepared from dimethyl terephthalate (DMT) via selective hydrogenation of the benzene ring. The main catalysts used include rhodium, nickel, palladium, and ruthenium, with the addition of auxiliaries such as barium, platinum, and calcium. The reaction temperature is 120–250°C, and the reaction pressure is 1–41 MPa, but generally, higher pressures are required to achieve relatively good reaction results. CN1099744A discloses a process for producing the corresponding dialkyl cyclohexanedicarboxylic acid ester from dialkyl phthalate via low-pressure catalytic hydrogenation, in which the generation and accumulation of carbon monoxide are suppressed to maintain the activity of the noble metal catalyst. However, the pressure in the examples of this patent is still as high as 12.5 MPa. CN1291783C discloses a catalyst for producing dimethyl 1,4-cyclohexanedicarboxylate. Its main active component is palladium, the support is alumina, and the promoter is a combination of two types: the first promoter is silicon dioxide, and the second promoter is Ru, a group VIII sub-element. Palladium accounts for 0.5-2% (by weight) of the total catalyst weight, silicon dioxide accounts for 0.01-0.5% (by weight), and Ru accounts for 0.01-0.5% (by weight). This catalyst features low hydrogenation reaction pressure and high catalytic activity, achieving a dimethyl phthalate conversion rate of 95-99% and a dimethyl 1,4-cyclohexanedicarboxylate selectivity of 94-98%. However, this catalyst requires ethyl acetate as a solvent for hydrogenation, the product contains byproducts from the hydrogenation of ethyl acetate, and the process increases the need for solvent separation, resulting in higher energy consumption.

[0005] Therefore, existing methods are limited by catalysts and hydrogenation processes, have harsh hydrogenation conditions, and the conversion and yield of the reaction are not as expected. Summary of the Invention

[0006] To address the above shortcomings, this invention provides a composite catalyst and a method for catalyzing the hydrogenation of dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate using the catalyst. This invention provides a catalyst with a noble metal supported on a composite support and its preparation method, exhibiting high hydrogenation activity and good stability. The catalyst of this invention can also partially activate the ester carbonyl group, especially during the hydrogenation of dimethyl terephthalate, enabling simultaneous hydrogenation of the ester group on the product dimethyl 1,4-cyclohexanedicarboxylate. The product is the effective product 1,4-cyclohexanediethanol, thus achieving co-production of the final product 1,4-cyclohexanediethanol during the preparation of intermediate products.

[0007] To achieve the above technical objectives, the technical solution of the present invention is as follows:

[0008] The technical objective of the first aspect of this invention is to provide a method for preparing a composite catalyst, comprising:

[0009] (1) Tetraethyl orthosilicate was added to a mixed solution of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and hydrochloric acid, stirred to dissolve, allowed to stand, and allowed to crystallize. The resulting mixture was cooled, filtered, and washed. It was then added to an aluminum source solution, and the pH was adjusted to 1.5-3.0, preferably 2.0-2.5. USY molecular sieve was added while stirring. The mixture was transferred to a reactor for hydrothermal reaction. The product was dried and calcined to obtain Al-SBA-15 / USY composite support.

[0010] (2) A soluble salt containing Ru and Zn was prepared into a precursor solution containing both Ru and Zn metals. The solution was slowly dropped onto the Al-SBA-15 / USY composite support, mixed evenly, impregnated, and then dried and calcined to obtain the RuZn / Al-SBA-15 / USY catalyst.

[0011] Furthermore, in step (1), P123 is first mixed and dissolved in hydrochloric acid solution under water bath, ultrasonic and stirring conditions. The water bath temperature is 30-50℃, preferably 35-40℃; the mass fraction of hydrochloric acid used is 5%-10%, preferably 6%-10%; after adding P123 and dissolving, the mass fraction is 4%-8%, preferably 4%-6%.

[0012] Furthermore, the weight ratio of tetraethyl orthosilicate to P123 added in step (1) is 1.8:1-3:1, preferably 2:1-2.5:1.

[0013] Furthermore, the temperature of the crystallization reaction is 90-110℃, preferably 90-100℃, and the reaction time is 12-24h, preferably 12-20h.

[0014] Furthermore, the aluminum source in step (1) is selected from at least one of aluminum nitrate, aluminum sulfate and aluminum chloride, the mass fraction of aluminum source in the solution is 10%-20%, and the weight ratio of aluminum source solution to the above-mentioned washed mixture is 0.3:1-1:1, preferably 0.4:1-0.6:1.

[0015] Furthermore, the washing process uses distilled water and involves repeated washing until the system is neutral.

[0016] Furthermore, the pH adjustment is performed using ammonia water, with an ammonia water mass fraction of 10%-25%, preferably 15%-20%.

[0017] Furthermore, the weight ratio of USY to P123 added in step (1) is 1.5:1-2.5:1, preferably 1.5:1-2:1.

[0018] Furthermore, the temperature of the hydrothermal reaction in step (1) is 140-180℃, preferably 150-160℃, and the reaction time is 18-36h, preferably 24-36h.

[0019] Furthermore, the product after the hydrothermal reaction in step (1) is first washed repeatedly with ethanol and / or distilled water until the system is neutral. The drying temperature is 80-130℃, preferably 90-120℃, and the drying time is 12-24h, preferably 18-24h; the calcination temperature is 550-650℃, preferably 500-600℃, and the calcination time is 4-12h, preferably 4-8h.

[0020] Furthermore, in step (2), the soluble salt of Ru is selected from at least one of ruthenium chloride, ruthenium acetate and ruthenium nitrite, preferably ruthenium chloride; the soluble salt of Zn is selected from at least one of zinc chloride and zinc nitrate, preferably zinc nitrate.

[0021] Furthermore, the volume of the precursor solution containing Ru and Zn is the same as that of the composite carrier, and an equal-volume impregnation is performed for 12-48 hours, preferably 24-48 hours.

[0022] Furthermore, after impregnation, the system is washed and filtered with ethanol and / or distilled water until it is neutral.

[0023] Furthermore, the drying temperature in step (2) is 60-100℃, preferably 65-90℃, and the drying time is 12-24h, preferably 18-24h; the calcination temperature is 550-650℃, preferably 500-600℃, and the calcination time is 4-12h, preferably 6-8h.

[0024] Furthermore, based on the total weight of the catalyst, the mass fraction of metallic Ru in the catalyst is 0.3wt%-5.0wt%, preferably 1.5wt%-3.0wt%, and the mass fraction of metallic Zn in the catalyst is 5.0wt%-20.0wt%, preferably 10.0wt%-20.0wt%.

[0025] The technical objective of the second aspect of this invention is to provide a composite catalyst prepared by the above method.

[0026] The technical objective of the third aspect of this invention is to provide a method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation of dimethyl terephthalate, wherein dimethyl terephthalate is contacted with the composite catalyst to undergo a hydrogenation reaction.

[0027] Furthermore, the composite catalyst is first reduced with hydrogen before catalyzing the above reaction.

[0028] Furthermore, the reduction is carried out using a method well known to those skilled in the art, specifically using hydrogen as a reducing agent, a reduction temperature of 400-600℃, preferably 450-500℃, and a reduction time of 3-12h, preferably 4-8h.

[0029] Furthermore, the reaction conditions for the hydrogenation reaction are as follows: reaction temperature of 100-260℃, preferably 120-200℃, reaction pressure of 1-9MPa, preferably 1-6MPa, and liquid feed space velocity of 0.05-5h. -1 Preferred time: 0.1-3h -1 The hydrogen-liquid molar ratio is 50:1-500:1, preferably 50:1-300:1.

[0030] Furthermore, the specific process of the hydrogenation reaction is as follows: using dimethyl terephthalate as raw material, a fixed-bed reactor is used, the reactor is filled with the composite catalyst, hydrogen gas is first introduced for purging, and then the raw material feed stream is introduced, so that dimethyl terephthalate undergoes a hydrogenation reaction on the catalyst surface to obtain dimethyl 1,4-cyclohexanedicarboxylate.

[0031] Furthermore, the raw material dimethyl terephthalate is pre-dissolved in an organic solvent, which is selected from at least one of methanol, ethanol, butanol, n-propanol and isopropanol, preferably isopropanol; the mass fraction of dimethyl terephthalate in the formed solution is 1.5%-25%, preferably 5%-15%.

[0032] More specifically, the fixed-bed reactor, pumps, pipelines, etc., used in the above reaction are all equipped with insulation devices. During the reaction, the insulation of the fixed-bed pipelines, pumps, tanks, etc., is first turned on, and the system temperature and pressure are adjusted to the reaction temperature and pressure. Then, the H2 flow rate is adjusted to the reaction conditions to ensure a certain hydrogen-liquid molar ratio. The feed pump of the raw material tank is then turned on to ensure a certain liquid hourly space velocity (LHSV) for feeding, and the device begins the one-step hydrogenation reaction. Samples are taken from the product receiving tank at the end of the reaction at regular intervals for product analysis.

[0033] The above catalyst was used to catalyze the hydrogenation of dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate. The conversion rate of dimethyl terephthalate was ≥78%, the selectivity of the prepared dimethyl 1,4-cyclohexanedicarboxylate was ≥80%, and the mass concentration of the effective product 1,4-cyclohexanediethanol was ≥20wt%.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The catalyst of the present invention introduces metal Ru and Zn during the preparation process to easily form Ru-Zn alloy. The formation of this alloy changes the electronic structure of the catalyst surface, which enables the catalyst to coordinate with the reactants more effectively, improves the catalytic activity, promotes the activation of the benzene ring on dimethyl terephthalate by the catalyst, makes the cyclohydrogenation reaction easier to occur, the catalyst reaction temperature is low, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate is high.

[0036] (2) The RuZn / Al-SBA-15 / USY catalyst prepared by the impregnation method in this invention has modified metals uniformly dispersed on the composite support, which reduces the agglomeration of active metals and is conducive to enhancing the adsorption of dimethyl terephthalate molecules by the catalyst, thereby improving catalytic activity and catalyst stability. In addition, the active sites of metal Al and many specific functional groups on the composite support Al-SBA-15 / USY, as L acid sites, can attract electron-rich groups such as C=O on the reactants and synergistically promote the activation of some ester carbonyl groups on dimethyl terephthalate, so that the ester groups on the product 1,4-cyclohexanedimethyl terephthalate are hydrogenated simultaneously. The product is the effective product 1,4-cyclohexanediethanol, which is beneficial to the next step of ester hydrogenation reaction.

[0037] (3) The catalyst support Al-SBA-15 / USY of the present invention has a suitable pore diameter and has a cavity size effect, which can change the diffusion kinetics of 1,4-cyclohexanedicarboxylate in the cavity, so that the catalyst has a certain selectivity for 1,4-cyclohexanediethanol and can increase the concentration of 1,4-cyclohexanediethanol in the product.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0039] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0040] The method and effects of the present invention will be further described in detail below with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples can be purchased from biochemical reagent stores.

[0042] This invention uses an inductively coupled plasma optical emission spectrometer (ICP-OES) with SPECTRO ARCOSⅡ to quantitatively analyze the actual element loading in the catalyst.

[0043] The conversion rate of dimethyl terephthalate, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate, and the concentration of 1,4-cyclohexanediethanol in the product were determined by gas chromatography-quantitative analysis. Gas chromatography conditions: SHIMADZU GC-2030 gas chromatograph with FID detector; SE-54 capillary column, 30m × 0.25mm × 0.25μm; injection port temperature 280℃; injection volume 1μL; split injection, split ratio 50:1; column initial temperature 160℃, increased to 270℃ at a rate of 8℃ / min, held for 5 min; then increased to 300℃ at a rate of 15℃ / min, held for 5 min; detector temperature 280℃.

[0044] (1) Dimethyl terephthalate conversion rate:

[0045] X = (A0 - A1) / A0 × 100%

[0046] In the formula: X—conversion rate of dimethyl terephthalate; A0—percentage of peak area of ​​dimethyl terephthalate in the raw material, %; A1—percentage of peak area of ​​dimethyl terephthalate in the product, %.

[0047] (2) Selectivity of dimethyl 1,4-cyclohexanedicarboxylate:

[0048] Y = (B DMCD / 200) / ((A0-A1) / 194)×100%

[0049] In the formula: Y—dimethyl 1,4-cyclohexanedicarboxylate is selective; B DMCD —Percentage of peak area of ​​dimethyl 1,4-cyclohexanedicarboxylate in the product, %.

[0050] (3) Concentration of 1,4-cyclohexanediethanol in the product:

[0051] W CHDM =C CHDM

[0052] In the formula: W CHDM —Concentration of 1,4-cyclohexanediethanol in the product, %;

[0053] C CHDM —Percentage of 1,4-cyclohexanediethanol peak area in the product, %.

[0054] Example 1

[0055] Catalyst preparation process:

[0056] (1) Preparation of composite carrier: Under ultrasonic, stirring, and 38℃ water bath conditions, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) was dissolved in 8% hydrochloric acid solution to make the mass fraction of P123 5%; tetraethyl orthosilicate was added dropwise, with a weight ratio of m(tetraethyl orthosilicate):m(P123) = 2:1, and stirring was continued to dissolve. Then, the mixture was allowed to stand and crystallize at 95℃ for 20h. The resulting mixture was cooled to room temperature, filtered, and washed until the system was neutral; then, it was added to 15% aluminum nitrate solution, with a weight ratio of aluminum nitrate solution to the washed mixture of the above mixture of 0.6:1; the pH was adjusted to 2.40 using 20% ​​ammonia water; USY was added with stirring to make the ratio of m(USY):m(P123) = 1.5:1. The mixture was transferred to a hydrothermal reactor and reacted at 150℃ for 24h, and repeatedly washed with ethanol and distilled water until the system was neutral. The product was dried in an oven at 120°C for 24 hours, and then calcined in a muffle furnace at 600°C for 4 hours to obtain the Al-SBA-15 / USY composite carrier.

[0057] (2) Impregnation modification: A precursor solution containing both Ru and Zn metals was prepared using ruthenium chloride and zinc nitrate precursor salts. An equal volume was slowly added dropwise to the Al-SBA-15 / USY composite support, and impregnated at room temperature for 24 h. The solution was washed with ethanol and distilled water, and filtered until the system was neutral. It was then dried at 90 °C for 24 h and calcined at 600 °C for 8 h to prepare RuZn / Al-SBA-15 / USY catalyst A. ICP-OES analysis showed that the mass fraction of Ru metal in the catalyst was 2.02 wt%, and the mass fraction of Zn metal was 20.11 wt%.

[0058] The hydrogenation reaction process for the preparation of dimethyl 1,4-cyclohexanedicarboxylate from dimethyl terephthalate: 10 mL of catalyst A was loaded into a fixed-bed reactor and first reduced with H2 at 500℃ for 8 h. Isopropanol was used as the solvent and mixed with the feedstock dimethyl terephthalate (10% by mass). The feedstock was fed at 80℃ while maintaining the temperature. Simultaneously, the insulation of the fixed-bed pipelines, pumps, tanks, etc., was turned on, and the reaction temperature was adjusted to 160℃, the pressure to 4 MPa, and the liquid hourly space velocity to 1 h⁻¹. -1 The hydrogen-liquid molar ratio was 200:1, catalyzing the reaction of dimethyl terephthalate. Samples were taken periodically from the product receiving tank at the tail end of the reaction for analysis. The conversion rate of dimethyl terephthalate was determined to be 85.1%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 86.7%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 23.9 wt%.

[0059] Example 2

[0060] The same catalyst as in Example 1 was used, with the same loading amount.

[0061] The hydrogenation reaction process for the preparation of dimethyl 1,4-cyclohexanedicarboxylate from dimethyl terephthalate: Catalyst A is packed into a fixed-bed reactor and first reduced with H2 at 500℃ for 8 hours. Isopropanol is used as a solvent and mixed with the feedstock dimethyl terephthalate (10% by mass). The feedstock is fed at 80℃ while maintaining the temperature. Simultaneously, the insulation of the fixed-bed pipelines, pumps, tanks, etc., is turned on, and the reaction temperature is adjusted to 120℃, the pressure to 4 MPa, and the liquid hourly space velocity to 1 h⁻¹. -1 The hydrogen-liquid molar ratio was 50:1, catalyzing the reaction of dimethyl terephthalate. Samples were taken periodically from the product receiving tank at the tail end of the reaction for analysis. The conversion rate of dimethyl terephthalate was determined to be 78.0%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 88.1%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 24.0 wt%.

[0062] Example 3

[0063] The same catalyst as in Example 1 was used, with the same loading amount.

[0064] The hydrogenation reaction process for the preparation of dimethyl 1,4-cyclohexanedicarboxylate from dimethyl terephthalate: Catalyst A is loaded into a fixed-bed reactor and first reduced with H2 at 500℃ for 8 hours. Isopropanol is used as a solvent and mixed with the feedstock dimethyl terephthalate (10% by mass). The feedstock is fed at 80℃ while maintaining the temperature. Simultaneously, the insulation of the fixed-bed pipelines, pumps, tanks, etc., is turned on, and the reaction temperature is adjusted to 200℃, the pressure to 6 MPa, and the liquid hourly space velocity to 1 h⁻¹. -1 The hydrogen-liquid molar ratio was 200:1, catalyzing the reaction of dimethyl terephthalate. Samples were taken periodically from the product receiving tank at the tail end of the reaction for analysis. The conversion rate of dimethyl terephthalate was determined to be 86.5%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 86.9%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 23.4 wt%.

[0065] Example 4

[0066] The same catalyst as in Example 1 was used, with the same loading amount.

[0067] The hydrogenation reaction process for the preparation of dimethyl 1,4-cyclohexanedicarboxylate from dimethyl terephthalate: Catalyst A was loaded into a fixed-bed reactor and first reduced with H2 at 500℃ for 8 hours. Isopropanol was used as a solvent and mixed with the feedstock dimethyl terephthalate (10% by mass). The feedstock was fed at 80℃ while maintaining the temperature. Simultaneously, the insulation of the fixed-bed pipelines, pumps, tanks, etc., was turned on, and the reaction temperature was adjusted to 160℃, the pressure to 1 MPa, and the liquid hourly space velocity to 0.1 h⁻¹. -1 The hydrogen-liquid molar ratio was 200:1, catalyzing the reaction of dimethyl terephthalate. Samples were taken periodically from the product receiving tank at the tail end of the reaction for analysis. The conversion rate of dimethyl terephthalate was determined to be 82.1%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 83.2%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 22.1 wt%.

[0068] Example 5

[0069] The same catalyst as in Example 1 was used, with the same loading amount.

[0070] The hydrogenation reaction process for the preparation of dimethyl 1,4-cyclohexanedicarboxylate from dimethyl terephthalate: Catalyst A is packed into a fixed-bed reactor and first reduced with H2 at 500℃ for 8 hours. Isopropanol is used as a solvent and mixed with the feedstock dimethyl terephthalate (10% by mass). The feedstock is fed at 80℃ while maintaining the temperature. Simultaneously, the insulation of the fixed-bed pipelines, pumps, tanks, etc., is turned on, and the reaction temperature is adjusted to 160℃, the pressure to 4 MPa, and the liquid hourly space velocity to 3 h⁻¹. -1 The hydrogen-liquid molar ratio was 300:1, catalyzing the reaction of dimethyl terephthalate. Samples were taken periodically from the product receiving tank at the tail end of the reaction for analysis. The conversion rate of dimethyl terephthalate was determined to be 83.4%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 86.8%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 23.3 wt%.

[0071] Example 6

[0072] The RuZn / Al-SBA-15 / USY catalyst B was prepared using the same method as in Example 1, except that the concentration of the Ru-containing precursor solution was different during the metal impregnation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.91 wt%, the mass fraction of metallic Zn was 19.53 wt%, the catalyst loading was 15 mL, and other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 85.3%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 84.1%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 21.1 wt%.

[0073] Example 7

[0074] The RuZn / Al-SBA-15 / USY catalyst C was prepared using the same method as in Example 1, except that the concentration of the Ru-containing precursor solution was different during the metal impregnation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 1.50 wt%, the mass fraction of metallic Zn was 19.98 wt%, the catalyst loading was 20 mL, and other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 81.3%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 82.5%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 22.3 wt%.

[0075] Example 8

[0076] The RuZn / Al-SBA-15 / USY catalyst D was prepared using the same method as in Example 1, except that the concentration of the Zn-containing precursor solution was different during the metal impregnation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.10 wt%, the mass fraction of metallic Zn was 10.11 wt%, and the catalyst loading was 10 mL. Other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 84.7%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 81.5%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 20.4 wt%.

[0077] Example 9

[0078] The RuZn / Al-SBA-15 / USY catalyst E was prepared using the same method as in Example 1, except that the concentration of the Zn-containing precursor solution was different during the metal impregnation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.03 wt%, the mass fraction of metallic Zn was 15.12 wt%, the catalyst loading was 20 mL, and other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 84.8%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 82.2%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 20.5 wt%.

[0079] Example 10

[0080] The RuZn / Al-SBA-15 / USY catalyst F was prepared using the same method as in Example 1. The difference was that during the preparation of the support, the weight ratio of aluminum nitrate solution to the washed mixture was 0.4:1. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.05 wt%, the mass fraction of metallic Zn was 19.14 wt%, the catalyst loading was 10 mL, and other reaction conditions were the same as in Example 1. After the reaction, the product was sampled and analyzed. The conversion rate of dimethyl terephthalate was 84.9%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 86.5%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 21.4 wt%.

[0081] Example 11

[0082] The RuZn / Al-SBA-15 / USY catalyst G was prepared using the same method as in Example 1, except that the ratio of m(USY):m(P123) was 2:1 during the support preparation process. ICP-OES analysis showed that the mass fraction of Ru in the catalyst was 2.02 wt%, the mass fraction of Zn was 19.24 wt%, and the catalyst loading was 10 mL. Other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 84.6%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 80.7%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 20.0 wt%.

[0083] Example 12

[0084] The RuZn / Al-SBA-15 / USY catalyst H was prepared using the same method as in Example 1, except that the mass fraction of P123 was 6% during the support preparation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.05 wt%, the mass fraction of metallic Zn was 19.65 wt%, and the catalyst loading was 10 mL. Other reaction conditions were the same as in Example 1. After the reaction, a sample of the product was taken for compositional analysis. The conversion rate of dimethyl terephthalate was 84.5%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 80.4%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 20.3 wt%.

[0085] Example 13

[0086] The RuZn / Al-SBA-15 / USY catalyst I was prepared using the same method as in Example 1. The difference was that during the preparation of the support, 20% ammonia was used to adjust the pH to 2.1. ICP-OES analysis showed that the mass fraction of Ru in the catalyst was 2.07 wt%, the mass fraction of Zn was 19.61 wt%, the catalyst loading was 10 mL, and other reaction conditions were the same as in Example 1. After the reaction, the product was sampled and analyzed. The conversion rate of dimethyl terephthalate was 84.0%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 80.0%, and the mass concentration of 1,4-cyclohexanediethanol in the product was 21.2 wt%.

[0087] Comparative Example 1

[0088] The single-metal Ru / Al-SBA-15 / USY catalyst was prepared using the same method as in Example 1, except that only a precursor solution containing Ru was used during the impregnation process. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.17 wt%, the catalyst loading was 10 mL, and other reaction conditions were the same as in Example 1. After the reaction, the product was sampled and analyzed. The conversion rate of dimethyl terephthalate was 50.1%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 15.6%, and 1,4-cyclohexanediethanol was not detected in the product.

[0089] Comparative Example 2

[0090] The composite bimetallic catalyst was prepared using the same method as in Example 1, except that a precursor solution of metallic Ca was used instead of Zn during the impregnation process to prepare RuCa / Al-SBA-15 / USY. ICP-OES analysis showed that the mass fraction of metallic Ru in the catalyst was 2.14 wt%, the mass fraction of Ca was 20.06 wt%, and the catalyst loading was 10 mL. Other reaction conditions were the same as in Example 1. After the reaction, product samples were taken for compositional analysis. The conversion rate of dimethyl terephthalate was 33.1%, the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 18.4%, and 1,4-cyclohexanediethanol was not detected in the product.

[0091] Comparative Example 3

[0092] The composite bimetallic catalyst was prepared using the same method as in Example 1, except that a simple Al-SBA-15 support was used to prepare RuZn / Al-SBA-15. ICP-OES analysis showed that the mass fraction of Ru in the catalyst was 2.11 wt% and the mass fraction of Zn was 20.12 wt%. The catalyst loading was 10 mL, and other reaction conditions were the same as in Example 1. After the reaction, samples of the product were taken for compositional analysis. The conversion rate of dimethyl terephthalate was 40.5%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 14.6%, and 1,4-cyclohexanediethanol was not detected in the product.

[0093] Comparative Example 4

[0094] The composite bimetallic catalyst was prepared using the same method as in Example 1, except that a simple USY support was used, resulting in a RuZn / USY catalyst. ICP-OES analysis showed that the mass fraction of Ru in the catalyst was 2.16 wt%, the mass fraction of Zn was 20.10 wt%, and the catalyst loading was 10 mL. Other reaction conditions were the same as in Example 1. After the reaction, samples of the product were taken for compositional analysis. The conversion rate of dimethyl terephthalate was 30.4%, the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 9.3%, and 1,4-cyclohexanediethanol was not detected in the product.

Claims

1. A method for preparing a composite catalyst, comprising: (1) adding tetraethyl orthosilicate to a mixed solution of P123 and hydrochloric acid, stirring to dissolve, standing, and performing a crystallization reaction, cooling, filtering, and washing the mixture obtained from the reaction; adding the mixture to an aluminum source solution, adjusting the pH to 1.5-3.0, continuing to stir while adding USY molecular sieve, transferring to a reaction kettle, and performing a hydrothermal reaction, drying the product, and calcining to obtain an Al-SBA-15 / USY composite carrier; (2) preparing a precursor solution containing Ru and Zn by dissolving soluble salts of Ru and Zn, slowly dropping the solution onto the Al-SBA-15 / USY composite carrier, mixing uniformly, impregnating, and then drying and calcining to obtain a RuZn / Al-SBA-15 / USY catalyst.

2. The production method according to claim 1, characterized by, In step (1), P123 is first mixed and dissolved in a hydrochloric acid solution under conditions of water bath, ultrasonic, and stirring, the water bath temperature is 30-50°C, the mass fraction of hydrochloric acid used is 5%-10%, and the mass fraction of P123 is 4%-8%.

3. The production method according to claim 1, characterized by, In step (1), the weight ratio of tetraethyl orthosilicate added to P123 is 1.8:1-3:

1.

4. The method of claim 1, wherein, The crystallization reaction temperature is 90-110°C, and the reaction time is 12-24h.

5. The preparation method according to claim 1, characterized in that, In step (1), the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, and aluminum chloride, the mass fraction of the aluminum source in the solution is 10%-20%, and the weight ratio of the aluminum source solution to the mixture after washing is 0.3:1-1:

1.

6. The method of claim 1, wherein, The pH is adjusted using ammonia water, and the mass fraction of the ammonia water is 10%-25%.

7. The preparation method according to claim 1, characterized in that, Further, in step (1), the weight ratio of USY added to P123 is 1.5:1-2.5:

1.

8. The method of claim 1, wherein, In step (1), the hydrothermal reaction temperature is 140-180°C, and the reaction time is 18-36h.

9. The method of claim 1, wherein, In step (1), the product after the hydrothermal reaction is first repeatedly washed with ethanol and / or distilled water until the system is neutral; the drying temperature is 80-130°C, the drying time is 12-24h; and the calcination temperature is 550-650°C, and the calcination time is 4-12h.

10. The method of claim 1, wherein, In step (2), the soluble salt of Ru is selected from at least one of ruthenium chloride, ruthenium acetate, and ruthenium nitrosylate, and the soluble salt of Zn is selected from at least one of zinc chloride and zinc nitrate.

11. The method of claim 1, wherein, The volume of the precursor solution containing Ru and Zn is the same as that of the composite carrier, and equal-volume impregnation is used, with an impregnation time of 12-48h.

12. The method of claim 1, wherein, In step (2), the drying temperature is 60-100°C, the drying time is 12-24h, the calcination temperature is 550-650°C, and the calcination time is 4-12h.

13. The method of claim 1, wherein, The mass fraction of metal Ru in the catalyst is 0.3wt%-5.0wt% based on the total weight of the catalyst, and the mass fraction of metal Zn in the catalyst is 5.0wt%-20.0wt%.

14. The composite catalyst prepared by the method of any one of claims 1-13.

15. Process for the hydrogenation of dimethyl terephthalate to dimethyl 1,4-cyclohexanedicarboxylate, characterized in that, Hydrogenation is performed by contacting dimethyl terephthalate with the composite catalyst of claim 14.

16. The method of claim 15, wherein, The composite catalyst is reduced by hydrogen before catalyzing the reaction.

17. The method of claim 15, wherein, The reaction conditions of the hydrogenation reaction are as follows: the reaction temperature is 100-260℃, the reaction pressure is 1-9 MPa, the liquid feed air speed is 0.05-5h -1 , and the hydrogen liquid mole ratio is 50:1-500:

1.

18. The method of claim 15, wherein, The specific process of the hydrogenation reaction is as follows: taking dimethyl terephthalate as the raw material, using a fixed bed reaction device, filling the composite catalyst in the reaction device, first blowing in hydrogen, then feeding the raw material, and making dimethyl terephthalate on the surface of the catalyst to have a hydrogenation reaction to obtain dimethyl 1,4-cyclohexane dicarboxylate; wherein the raw material dimethyl terephthalate is previously dissolved in an organic solvent, the organic solvent is selected from at least one of methanol, ethanol, butanol, n-propanol and isopropanol, and the mass fraction of dimethyl terephthalate in the formed solution is 1.5%-25%.