Method for microwave-assisted preparation of Ru-Sn-Mg hydrogenation catalyst, and catalyst and application thereof

Abstract

The application discloses a microwave-assisted preparation method of a Ru-Sn-Mg hydrogenation catalyst, and the catalyst and application, and belongs to the technical field of catalytic material preparation. The application is directed to the problems of uneven dispersion of active components, long reduction time and poor catalytic performance of the same catalyst prepared by traditional water bath heating reduction, and introduces a microwave-assisted hydrogen reduction technology on the basis of a precipitation-aging process. The precursor solution is placed in a 4-6 MPa hydrogen atmosphere, and reduction is completed in only 1-2 hours at a microwave power of 300-500 W and a reduction temperature of 120-160 DEG C, so that the preparation period is greatly shortened. The catalyst prepared by the method has an active component particle size of 5-10 nm and excellent dispersity, is used in a DMCD hydrogenation reaction to CHDM, and has a DMCD conversion rate of no less than 100% and a CHDM selectivity of no less than 92%, and the performance is significantly better than that of a traditional process. The application simultaneously protects the preparation method, the obtained catalyst and the application, and the process is high in efficiency and energy saving, strong in controllability, suitable for industrial production, and high in economic value and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation technology, specifically relating to a microwave-assisted method for preparing a Ru-Sn-Mg catalyst for the hydrogenation of dimethyl 1,4-cyclohexanedicarboxylate, the hydrogenation catalyst prepared by this method, and the application of this catalyst in the hydrogenation of dimethyl 1,4-cyclohexanedicarboxylate (DMCD) to 1,4-cyclohexanediethanol (CHDM), which is particularly suitable for the innovation of high-efficiency catalyst preparation processes in the field of fine chemical hydrogenation catalysis. Background Technology

[0002] 1,4-Cyclohexanediethanol (CHDM) is an important fine chemical intermediate widely used in polyester resins, coatings, and plastic additives. It possesses excellent heat resistance, mechanical strength, and optical properties, and market demand continues to rise. Currently, the industrial production of CHDM primarily utilizes the catalytic hydrogenation process of dimethyl 1,4-cyclohexanedicarboxylate (DMCD). The key lies in the development of highly efficient hydrogenation catalysts, among which Ru-Sn-Mg-based supported hydrogenation catalysts exhibit superior catalytic performance.

[0003] Existing Ru-Sn-Mg hydrogenation catalysts are mostly prepared using a precipitation-aging-conventional water bath heating reduction process. This process has several technical drawbacks: First, conventional water bath heating is an external conduction heating method, which has a slow heating rate and poor heating uniformity. This leads to the agglomeration of active components Ru and Sn during the reduction of the catalyst precursor, resulting in uneven particle size distribution and poor dispersibility, directly affecting the hydrogenation activity and target product selectivity of the catalyst. Second, the conventional water bath reduction temperature rises slowly, and the reduction reaction takes a long time, usually requiring 4-5 hours to complete the reduction. This results in a long preparation cycle, high energy consumption, and is not conducive to continuous industrial production. Third, the active component of the catalyst prepared by the traditional process has a relatively large particle size, resulting in insufficient exposure of catalytic active sites. This makes it difficult to further improve the DMCD hydrogenation conversion rate and CHDM selectivity, limiting product yield and production efficiency.

[0004] In view of the shortcomings of the existing technologies, developing a novel preparation process for Ru-Sn-Mg hydrogenation catalysts with short preparation cycle, uniform dispersion of active components and excellent catalytic performance has become a technical problem that urgently needs to be solved by those skilled in the art. It is also the key to breaking through the performance bottleneck of existing catalysts and realizing efficient industrial production. Summary of the Invention

[0005] Purpose of the invention:

[0006] To address the shortcomings of conventional water bath heating reduction methods for preparing Ru-Sn-Mg hydrogenation catalysts, such as uneven dispersion of active components, long reduction time, and high energy consumption, this invention provides a microwave-assisted method for preparing Ru-Sn-Mg hydrogenation catalysts. By introducing microwave-assisted reduction technology and utilizing the core characteristics of rapid and uniform microwave heating, the reduction process parameters are optimized, the preparation cycle is shortened, and the dispersion of active components is improved, thereby enhancing the hydrogenation catalytic performance of the catalyst. Furthermore, this invention provides the catalyst prepared by this method and its application in the hydrogenation of DMCD to CHDM, broadening the industrial application scenarios of the catalyst.

[0007] Technical solution:

[0008] This invention specifically relates to a microwave-assisted preparation method for Ru-Sn-Mg hydrogenation catalyst. This method adds a microwave-assisted hydrogen reduction step to the traditional precipitation-aging process. The specific process steps are as follows: First, soluble ruthenium salt, tin salt, and magnesium salt are dissolved in deionized water to prepare a mixed solution. A precipitant is added dropwise to carry out a precipitation reaction, resulting in a precipitate suspension. Second, the precipitate suspension is aged, filtered, and washed to obtain a catalyst precursor filter cake. Subsequently, the precursor filter cake is dispersed into a precursor solution, placed in a microwave reactor, and hydrogen is introduced to replace the air. The pressure is increased to 4-6 MPa in a hydrogen atmosphere, and microwave-assisted reduction is initiated. The microwave power is 300-500 W, the reduction temperature is 120-160℃, and the reduction time is 1-2 h. After reduction, the catalyst is cooled, filtered, washed, and dried to obtain the Ru-Sn-Mg hydrogenation catalyst.

[0009] Furthermore, the pH value of the precipitation reaction control system is 8-10, and the stirring temperature is 25-60℃.

[0010] Furthermore, the aging temperature of the suspension is from room temperature to 60°C, and the aging time is 2-4 hours.

[0011] Furthermore, the hydrogen replacement is performed 3-5 times to ensure that no air remains in the reactor.

[0012] Furthermore, the particle size of the active component of the prepared catalyst is 5-10 nm, and the dispersion is ≥95%.

[0013] Furthermore, the Ru-Sn-Mg hydrogenation catalyst is used for the hydrogenation of dimethyl 1,4-cyclohexanedicarboxylate to prepare 1,4-cyclohexanediethanol, characterized in that the DMCD conversion rate is ≥100% and the CHDM selectivity is ≥92% in the catalytic reaction. Beneficial effects

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] Microwave-assisted heating enables rapid heating and uniform heat distribution, reducing reduction time by more than 60%, significantly shortening the catalyst preparation cycle, reducing energy consumption and production costs, and making it suitable for large-scale industrial production. The active components have smaller particle sizes and more uniform dispersion, and the number of active sites is greatly increased, effectively improving the hydrogenation activity and selectivity of the catalyst and solving the technical problem of active component agglomeration in traditional processes. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are all within the scope of protection of the present invention.

[0017] Example 1: Microwave-assisted (500W) preparation of Ru-Sn-Mg catalyst for DMCD hydrogenation

[0018] First, the Ru-Sn-Mg catalyst was prepared: Ruthenium trichloride, stannous chloride, and magnesium chloride were weighed and dissolved in deionized water at a Ru:Sn:Mg molar ratio of 1:2:8 to prepare a 0.5 mol / L mixed solution; sodium carbonate solution was slowly added dropwise as a precipitant, the stirring temperature was 40℃, the pH value of the system was controlled to 9, and the mixture was stirred for 1 h until complete precipitation was obtained, resulting in a precipitate suspension; the suspension was aged at 40℃ for 3 h, filtered, and washed with deionized water until the filtrate was free of chloride ions, resulting in a precursor filter cake; the filter cake was dispersed in deionized water, transferred to a microwave reactor, and purged with hydrogen gas 4 times, pressurized to 5 MPa, set the microwave power to 400 W, heated to 140℃, and reduced at a constant temperature for 1.5 h; after cooling, the mixture was filtered, washed, vacuum dried at 60℃ for 6 h, and ground to obtain the Ru-Sn-Mg catalyst.

[0019] The hydrogenation reaction was then carried out: 8.6 g of methyl 1,4-cyclohexanedicarboxylate, 40 mL of isopropanol, and 0.3 g of the Ru-Sn-Mg catalyst prepared in the above process were added to a 100 mL high-pressure reactor. Hydrogen gas was introduced to replace the air in the reactor 5 times. The hydrogen pressure was adjusted to 3 MPa, the temperature was raised to 150 °C, the stirring rate was 700 r / min, and the reaction was carried out for 6 h. After the reaction was completed, the mixture was cooled to room temperature, the catalyst was separated by filtration, and the filtrate was analyzed by gas chromatography.

[0020] The active component has a particle size of 7 nm and a dispersibility of 96%; it is used in the hydrogenation reaction of DMCD, achieving a DMCD conversion rate of 100% and a CHDM selectivity of 93.2%.

[0021] Comparative Example 1: Hydrogenation of DMCD catalyzed by Ru-Sn-Mg catalyst prepared in a water bath

[0022] The catalyst underwent the same precipitation and aging process as in Example 1. Precursor reduction was performed using conventional water bath heating at a hydrogen pressure of 5 MPa, a water bath temperature of 140°C, and a reduction time of 4.5 h. The remaining steps were consistent with Example 1, resulting in a comparative catalyst. The catalyst was added according to the reaction process described in Example 1, following the mass ratio specified in Example 1, and its performance was tested.

[0023] The active component has a particle size of 18 nm and a dispersion of 78%; the DMCD conversion rate is 96.5% and the CHDM selectivity is 87.1%.

[0024] Example 2: Microwave-assisted (300W) preparation of Ru-Sn-Mg catalyst for DMCD hydrogenation

[0025] The microwave power was adjusted to 300W, the reduction temperature to 120℃, the reduction time to 2h, and the hydrogen pressure to 4MPa. The remaining steps were the same as in Example 1. Catalyst preparation and catalytic performance testing were then carried out.

[0026] The active component has a particle size of 6 nm, a dispersibility of 95.5%, a DMCD conversion rate of 100%, and a CHDM selectivity of 92.4%.

[0027] Example 3 Microwave-assisted (160) o C) Preparation of Ru-Sn-Mg catalyst for catalytic hydrogenation of DMCD

[0028] The catalyst was prepared using an adjusted microwave power of 500W and a reduction temperature of 160°C. o C, reduction time 1h, hydrogen pressure 6MPa, the remaining steps are the same as in Example 1, catalyst preparation and performance testing are carried out.

[0029] The active component has a particle size of 9 nm, a dispersion of 95%, a DMCD conversion rate of 100%, and a CHDM selectivity of 92.8%.

[0030] The comparison of the above experimental results shows that the microwave-assisted preparation method for Ru-Sn-Mg hydrogenation catalyst protected by this invention has significant advantages. The active component of the catalyst prepared by this method has a small particle size and high dispersion. When applied to the DMCD hydrogenation to CHDM reaction, it can achieve 100% DMCD conversion and CHDM selectivity ≥92%. At the same time, the method has a short reduction time, improved preparation efficiency, reduced energy consumption, precise and controllable process parameters, and high batch stability of the catalyst, making it more suitable for large-scale industrial production.

Claims

1. A method for microwave-assisted preparation of Ru-Sn-Mg hydrogenation catalyst, characterized in that, The process includes the following steps: First, soluble ruthenium salt, tin salt, and magnesium salt are dissolved in deionized water to prepare a mixed solution, and a precipitating agent is added dropwise to carry out a precipitation reaction to obtain a precipitate suspension; second, the precipitate suspension is aged, filtered, and washed to obtain a catalyst precursor filter cake. Subsequently, the precursor filter cake was dispersed into a precursor solution and placed in a microwave reactor. After replacing the air with hydrogen, the pressure was increased to 4-6 MPa hydrogen atmosphere, and microwave-assisted reduction was started. The microwave power was 300-500 W, the reduction temperature was 120-160℃, and the reduction time was 1-2 h. After the reduction was completed, the catalyst was cooled, filtered, washed, and dried to obtain the Ru-Sn-Mg hydrogenation catalyst.

2. The method according to claim 1, characterized in that, In step (1), the pH value of the precipitation reaction system is controlled at 8-10, and the stirring temperature is 25-60℃.

3. The method according to claim 1, characterized in that, In step (2), the aging temperature is from room temperature to 60°C, and the aging time is 2-4 hours.

4. The method according to claim 1, characterized in that, The hydrogen replacement is performed 3-5 times to ensure that no air remains in the reactor.

5. A Ru-Sn-Mg hydrogenation catalyst, characterized in that, The catalyst active component was prepared by any one of the microwave-assisted preparation methods described in claims 1-4, and the particle size was 5-10 nm with a dispersion of ≥95%.

6. The application of the Ru-Sn-Mg hydrogenation catalyst according to claim 5 in the hydrogenation of dimethyl 1,4-cyclohexanedicarboxylate to prepare 1,4-cyclohexanediethanol, characterized in that, The DMCD conversion rate in the catalytic reaction is ≥100%, and the CHDM selectivity is ≥92%.