CN-121988411-A - Copper-silicon catalyst treated by plasma and preparation method and application thereof

Abstract

The invention discloses a copper-silicon catalyst treated by plasma, a preparation method and application thereof. The method replaces the traditional high-temperature roasting and reduction process by performing dielectric barrier discharge plasma treatment on the copper-silicon catalyst precursor prepared by the traditional ammonia distillation method in the atmosphere of H 2 /Ar and the like. The method can realize high-efficiency reduction and high dispersion of copper at room temperature, regulate and control the proportion of Cu + /Cu 0 and strengthen the strong interaction between metal and carrier. The catalyst is used in the reaction of preparing glycol by hydrogenating dimethyl oxalate, and has activity, selectivity and stability higher than those of traditional heat treatment catalyst, dimethyl oxalate converting rate up to 100%, glycol selectivity >97% and stability over 1000 hr. The invention has simple process, low energy consumption and environment protection, and has wide industrial application prospect.

Inventors

• DU JIAQI
• ZHANG XINBO
• LI WENLONG
• WANG JIAJIE
• SONG YUANJIANG
• WANG XIAOLI
• WANG XINYAN
• HU ZHIBIAO
• LI YANG
• ZHAO ANMIN

Assignees

• 西南化工研究设计院有限公司

Dates

Publication Date

20260508

Application Date

20260204

Claims (10)

1. 1. A method for preparing a copper silicon catalyst by plasma treatment, which is characterized by comprising the following steps: (1) The preparation of the catalyst precursor comprises the steps of dissolving a certain amount of copper salt by using deionized water, adding ammonia water into the solution, and stirring to obtain a copper ammonia solution; (2) And (3) plasma treatment, namely placing the catalyst precursor obtained in the step (1) in a dielectric barrier plasma discharge area, and performing plasma treatment for a certain time in a specific atmosphere to obtain the required copper-silicon catalyst.
2. 2. The preparation method of claim 1, wherein in the step (1), the copper salt is selected from any one of copper nitrate, copper acetate and copper chloride, and the copper loading is 10-30 wt% based on the total weight of the catalyst.
3. 3. The method according to claim 1, wherein in the step (1), the silicon source is selected from one of silica sol and fumed silica.
4. 4. The preparation method of the water-based polyurethane foam is characterized in that in the step (1), ammonia water is added, stirring is carried out for 15+/-5 min, aging is carried out, the temperature is increased to 90+/-5 ℃ for ammonia evaporation, ammonia evaporation is finished when the pH value is=6-7, the drying temperature is 80-120 ℃, and the drying time is 4-12 hours.
5. 5. The method according to claim 1, wherein in the step (2), the specific atmosphere is a reducing gas H 2 or a mixed atmosphere of H 2 and Ar, and when a mixed atmosphere of H 2 and Ar is used, the volume fraction of H 2 is 5% -10%.
6. 6. The method of claim 1, wherein in the step (2), the power of the plasma treatment is 50-300W, and the treatment time is 5-60 min.
7. 7. A copper silicon catalyst prepared according to the method of any one of claims 1-6.
8. 8. The copper-silicon catalyst according to claim 7, wherein the catalyst contains copper nanoparticles, the average particle diameter of the copper nanoparticles is less than 5nm, and the active species copper exists in the forms of Cu 0 and Cu + .
9. 9. The use of the copper-silicon catalyst according to claim 7 in the reaction of preparing ethylene glycol by hydrogenating dimethyl oxalate.
10. 10. The method of claim 9, wherein in the reaction for preparing glycol by hydrogenating dimethyl oxalate, the reaction temperature is 180-220 ℃, the reaction pressure is 2.0-4.0 MPa, the molar ratio of hydrogen to dimethyl oxalate is 50-100:1, and the mass space velocity of dimethyl oxalate is 0.5-1.5 h -1 .

Description

Copper-silicon catalyst treated by plasma and preparation method and application thereof Technical Field The invention belongs to the technical field of catalyst preparation, relates to a copper-silicon catalyst which is treated by adopting a plasma technology and does not need high-temperature hydrogen reduction, and a preparation method thereof, and in particular relates to a copper-silicon catalyst treated by adopting a plasma, and a preparation method and application thereof. Background Ethylene glycol is an important chemical basic raw material and is mainly used for producing polyester fibers, antifreezing agents, unsaturated polyester resins and the like. In recent years, the continuous development of the polyester industry has driven a steady increase in ethylene glycol demand. At present, the ethylene glycol is mainly produced by using a petroleum route through ethylene oxide hydration in industry, and along with the increasing shortage of petroleum resources, the development of a non-petroleum route synthetic ethylene glycol technology using coal or natural gas as a raw material has important significance. The process route for preparing the ethylene glycol from the coal-made synthetic gas through the selective hydrogenation of the dimethyl oxalate has the characteristics of high atomic economy, low carbon, environmental protection and the like, and becomes an important route for producing the ethylene glycol by replacing a petroleum route. The preparation of ethylene glycol by hydrogenation of dimethyl oxalate is a key step in the process of preparing ethylene glycol from coal, and the dimethyl oxalate is firstly hydrogenated into an intermediate methyl glycolate, and then the methyl glycolate is further hydrogenated into the target product ethylene glycol. Copper-silicon catalysts are widely used in ester hydrogenation reactions due to their good hydrogenation activity and high selectivity to ethylene glycol. The catalytic performance is mainly dependent on the dispersity, valence distribution and interaction between copper and the carrier. Conventional preparation methods such as impregnation, deposition-precipitation, and the like typically require high temperature calcination and high temperature reduction with hydrogen to activate the catalyst. However, the high temperature process tends to cause sintering and growth of copper particles, reduce the number of effective active sites, and may impair the interaction between the metal and the support, resulting in reduced catalyst activity, selectivity and stability. Meanwhile, the high-temperature treatment also increases the energy consumption cost of the catalyst preparation process. Therefore, a method for preparing a catalyst under mild conditions is needed to realize effective regulation and control of copper dispersity and valence state and strengthen the interface effect of copper and a silicon dioxide carrier. The method is important to further improve the performance of the copper-silicon catalyst in the reaction of preparing ethylene glycol by hydrogenating dimethyl oxalate and optimize the whole technology of preparing ethylene glycol by coal. Plasma treatment has been introduced as a simple and scalable technique for selectively activating catalysts because it can rapidly change the surface chemical state of the catalyst at room temperature to increase catalytic activity. Patent CN 106268808A discloses a copper-based ester hydrogenation catalyst prepared by a hydrogen plasma method, and the carrier is a carbon material. The catalyst is applied to the reaction of preparing glycol by hydrogenating dimethyl oxalate, improves the conversion rate of dimethyl oxalate and the selectivity of glycol under higher reaction temperature and pressure, but does not fully relate to the problem of long-period stability of the catalyst. CN 103480374A discloses a copper-silicon catalyst treated by low temperature plasma, which is used for the reaction of preparing ethanol by hydrogenation of acetate, and the stability of the catalyst is better than that of a conventional catalyst which is not treated by plasma within 150 hours. Although the prior art has attempted to improve the performance of copper catalysts using plasma technology, these methods generally fail to significantly enhance the catalytic effect and, in most cases, fail to completely avoid the high temperature reduction process or fail to adequately address the adverse effects of high temperature reduction on the structural stability of the catalyst, such as sintering and migration of active components. Therefore, a new method capable of thoroughly avoiding the high-temperature reduction step and synchronously optimizing the activity, the selectivity and the stability of the catalyst by regulating and controlling the plasma treatment condition is developed, and the method has important technical value and practical requirements. Disclosure of Invention The invention aims to overcome the de