Sn-Zn / CeCu catalyst for Rochw-Muller reaction as well as preparation method and application of Sn-Zn / CeCu catalyst

Abstract

The invention relates to a Sn-Zn / CeCu catalyst for a Rochw-Muller reaction as well as a preparation method and application of the Sn-Zn / CeCu catalyst. The invention relates to a preparation method of a Sn-Zn / CeCu catalyst for Rochw-Muller reaction. The preparation method comprises the following steps: (1) preparing a nanorod-shaped CeCu catalyst; (2) carrying out zinc loading by taking the CeCu catalyst as a substrate to obtain a Zn / CeCu catalyst; and (3) carrying out tin loading by taking the Zn / CeCu catalyst as a substrate, so as to obtain the Sn-Zn / CeCu catalyst. According to the Sn-Zn / CeCu catalyst for the Rochw-Muller reaction as well as the preparation method and the application of the Sn-Zn / CeCu catalyst, the prepared catalyst can effectively improve the yield and the conversion rate of dimethyldichlorosilane, the preparation method is simple, no excessive waste water difficult to treat exists, the Sn-Zn / CeCu catalyst is suitable for industrial production, good economic benefits can be generated, and the Sn-Zn / CeCu catalyst is suitable for industrial production. And moreover, the used raw materials are low in cost and less in dosage, and are suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of organosilicon monomer synthesis, and particularly relates to an Sn-Zn / CeCu catalyst for the Rochow-Müller reaction, a preparation method thereof, and an application thereof. Background Art

[0002] Organosilicon is a class of high-performance new materials composed of alternating silicon-oxygen main chains and side chains attached to aliphatic or aromatic groups. It combines the excellent properties of inorganic and organic compounds, has basic properties such as a small viscosity coefficient, low surface tension, high gas osmotic pressure, and high compressibility, and also has excellent properties such as radiation resistance, high and low temperature resistance, corrosion resistance, electrical insulation, hydrophobicity, flame retardancy, and emission safety. Therefore, it is widely used in the fields of electronics, electrical appliances, aerospace, construction, medicine, etc.

[0003] The organosilicon industrial chain can be divided into raw materials, organosilicon monomers, organosilicon intermediates, and deep-processed products. Its production process can be divided into the following parts: monomer preparation, monomer hydrolysis and polycondensation to form oligomers, and processing of oligomers into different types of organosilicon products, etc. Methylchlorosilane is the organosilicon monomer with the highest consumption in the preparation of organosilicon products and is the pillar of the entire organosilicon industrial chain. In polysiloxanes, introducing fluorosilane, vinyl, phenyl, etc. can derive various organic polymers with excellent properties, and most organosilicon materials contain polysiloxanes made from dimethyldichlorosilane (M2). Therefore, among methylchlorosilanes, M2 accounts for an absolute majority, accounting for 90% of the monomer production, and is the key to the organosilicon production chain.

[0004] The synthesis of M2 is obtained by the reaction of metallic silicon and chloromethane, called the Rochow-Müller reaction. In addition to generating M2, other by-products will also be generated, such as methyltrichlorosilane (M1), trimethylchlorosilane (M3), low boilers, high boilers, etc.

[0005] CuO is an important catalyst for the Rochow-Müller reaction in industry. It has the characteristics of low price, high specific surface area and porosity, small particle size, appropriately exposed crystal planes, and is easy to prepare and store. However, with the increasing demand for organosilicon, its catalytic performance is no longer sufficient to meet the market demand. Therefore, improving the selectivity and yield of M2 is the key.

[0006] The performance of the catalyst is mainly changed through three aspects: morphology, valence state, and electronic effect. Size and morphology are of great significance in determining the performance of nanomaterials. Different morphologies of CuO nanomaterials have important effects on specific surface area, surface charge distribution, oxygen vacancies, etc. Valence state is also one of the reasons affecting catalytic performance. Compared with single CuO, after being loaded with different metals, more Cu will appear on the surface of CuO+ , while Cu + is the key to determining the performance of the catalyst; the electronic effect also plays an important role in the catalytic performance of the catalyst. Abundant oxygen vacancies can enhance the interaction between O 2 and the oxide surface, promote electron transfer to produce abundant reactive oxygen species, and improve the catalytic performance.

[0007] Currently, ternary copper is often used as a catalyst in industry and is used in combination with various additives to form a catalyst. However, the cost of ternary copper is significantly higher than that of CuO, and simple mechanical mixing will result in insufficient use of the additives, thereby increasing the cost. However, a single CuO catalyst is no longer sufficient to meet the current industrial needs.

[0008] In view of this, the present invention proposes a catalyst for the Rochow-Müller reaction to synthesize dimethyldichlorosilane and a preparation method thereof. The constructed Sn-Zn / CeCu composite catalyst improves the formation of oxygen vacancies, promotes the generation of active sites, and ultimately promotes the improvement of the reaction conversion rate and selectivity in the Rochow-Müller reaction. Summary of the Invention

[0009] The object of the present invention is to provide a preparation method of an Sn-Zn / CeCu catalyst for the Rochow-Müller reaction, and this preparation method is simple and easy to implement.

[0010] In order to achieve the above object, the technical solution adopted is as follows:

[0011] A preparation method of an Sn-Zn / CeCu catalyst for the Rochow-Müller reaction, comprising the following steps:

[0012] (1) Prepare a nanorod-shaped CeCu catalyst;

[0013] (2) Using the CeCu catalyst as a substrate, perform zinc loading to obtain a Zn / CeCu catalyst;

[0014] (3) Using the Zn / CeCu catalyst as a substrate, perform tin loading to obtain the Sn-Zn / CeCu catalyst.

[0015] Further, in the step (1), the steps for preparing the CeCu catalyst are as follows: Dissolve Cu(NO 3 ) 2 ·3H 2 O, Ce(NO 3 ) 3 ·6H 2After O is completely dissolved in ethanol, add NaOH solution, mix evenly and then carry out hydrothermal reaction. After the reaction is completed, cool, filter, wash, dry and calcine.

[0016] Furthermore, the mass-volume ratio of Cu(NO 3 ) 2 ·3H 2 O, Ce(NO 3 ) 3 ·6H 2 O and ethanol is 1 - 1.5 g : 0.1 - 0.3 g : 10 - 15 mL;

[0017] The hydrothermal reaction is at 150 - 200 °C and the reaction time is 18 - 24 h;

[0018] The drying temperature is 50 - 70 °C and the drying time is 8 - 12 h;

[0019] The calcination temperature is 400 - 600 °C and the calcination time is 6 - 8 h.

[0020] Furthermore, the step of zinc loading in step (2) is: evenly disperse the CeCu catalyst into an ethanol aqueous solution, then add Zn(NO 3 ) 2 ·6H 2 O solution, stir for 1 - 3 h, filter, wash, dry and calcine.

[0021] Furthermore, the mass ratio of the CeCu catalyst to Zn(NO 3 ) 2 ·6H 2 O is 1.0 - 1.5 : 0.1 - 0.2;

[0022] The volume ratio of water to ethanol in the ethanol aqueous solution is 1 - 2 : 1 - 2;

[0023] The drying temperature is 30 - 70 °C and the drying time is 8 - 12 h;

[0024] The calcination temperature is 400 - 600 °C and the calcination time is 2 - 6 h.

[0025] Furthermore, the step of tin loading in step (3) is: evenly disperse the Zn / CeCu catalyst into an ethanol aqueous solution, then add SnCl 4 ·5H 2 O solution, stir for 1 - 2 h, filter, wash and dry.

[0026] Furthermore, the mass ratio of the Zn / CeCu catalyst to SnCl 4 ·5H2 The mass ratio of O is 1.0 - 1.5: 0.0001 - 0.0003;

[0027] The volume ratio of water to ethanol in the aqueous ethanol solution is 1 - 2: 1 - 2;

[0028] The drying temperature is 60 - 80 °C, and the drying time is 8 - 12 h.

[0029] Another object of the present invention is to provide an Sn-Zn / CeCu catalyst for the Rochow-Müller reaction, which is prepared by the above preparation method. This catalyst has higher catalytic performance and good stability, and is a Rochow-Müller reaction catalyst that can achieve high conversion rate and high selectivity.

[0030] Another object of the present invention is to provide the application of the above-mentioned Sn-Zn / CeCu catalyst for the Rochow-Müller reaction in the Rochow-Müller reaction.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] In view of the problems of insufficient activity and easy carbon deposition and deactivation existing in traditional Rochow-Müller reaction catalysts, the present invention constructs a quaternary composite metal oxide catalytic system. By constructing a dynamic electron pair (Cu + / Ce 4+ and Cu 2+ / Ce 3+ ) in the Cu-Ce bimetallic oxide, the electronic structure limitation of traditional single-metal catalysts is broken through. This electron pair system not only significantly increases the concentration of Cu + active sites, but also forms gradient oxygen vacancies through the oxygen storage characteristics of CeO 2 , promotes the activation of lattice oxygen, and improves the generation efficiency of the active intermediate Cu X Si.

[0033] The present invention uses the synergistic effect of Zn-Sn bifunctional additives to solve the problem of carbon deposition. ZnO reduces carbon deposition by regulating the chloromethane methylation path; while SnO 2 depolymerizes the Cu X Si active phase through the intergranular diffusion mechanism, dynamically reconstructs the catalyst surface, and realizes the stable operation of the catalyst for 48 consecutive hours.

[0034] The present invention has developed an industrial-grade synthesis process with a low metal loading (total metal content < 5 wt%). Through the in-situ composite technology of metal precursors, the nano-scale uniform dispersion of quaternary components is realized. This process does not require special equipment, the three wastes discharge is basically zero, and the production cost of the catalyst is reduced compared with the traditional process. Description of the Drawings

[0035] Figure 1 Scanning electron microscope images of CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0036] Figure 2 Transmission electron microscope spectra of CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0037] Figure 3 XRD spectra of CuO, CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0038] Figure 4 XPS spectra of CuO, CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0039] Figure 5 H 2 -TPR spectra of CuO, CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0040] Figure 6 Reaction performance spectra of CuO, CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention;

[0041] Figure 7 Catalyst stability spectra of CuO, CuCe, Zn / CuCe, and Sn-Zn / CuCe prepared in Example 1 of the present invention. Detailed Description of the Invention

[0042] In order to further illustrate a Sn-Zn / CeCu catalyst for the Rochow-Müller reaction and its preparation method and application according to the present invention to achieve the expected invention purpose, the following combines preferred embodiments to detail the specific implementation manner, structure, characteristics, and effects of a Sn-Zn / CeCu catalyst for the Rochow-Müller reaction and its preparation method and application proposed according to the present invention. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0043] The following will further introduce in detail a Sn-Zn / CeCu catalyst for the Rochow-Müller reaction and its preparation method and application according to the present invention in combination with specific embodiments:

[0044] The Rochow-Müller reaction is a complex "gas-solid-solid" reaction. Besides the target product M2, there are other products, such as M1, M3, H1M, H2M, etc. Among them, the active intermediate site is Cu X The quantity of Si and its survival time determine the selectivity of M2 and the conversion rate of silicon powder. The copper-cerium material can provide more oxygen vacancies and active sites, thus generating more active intermediates. The incorporation of zinc can more easily activate methyl chloride molecules, making it easier to generate M2. By utilizing the characteristics of cerium and the role of zinc in the Rochow-Müller reaction, the present invention prepares a zinc-loaded copper-cerium catalyst to increase the generation and survival time of active intermediates, achieving a high improvement in selectivity and conversion rate.

[0045] The present invention prepares a rod-shaped copper-cerium catalyst by regulating the ratio of reactant raw materials and the hydrothermal temperature. Using this as a substrate, zinc is loaded to prepare a zinc-loaded rod-shaped copper-cerium catalyst. This catalyst has a simple synthesis method, can provide more active sites, more easily activate methyl chloride molecules, generate the reaction active intermediate Cu X Si, and the survival time of the reaction active intermediate is longer, thereby improving the selectivity and conversion rate of the reaction.

[0046] The technical solution of the present invention is as follows:

[0047] A preparation method of an Sn-Zn / CeCu catalyst for the Rochow-Müller reaction, comprising the following steps:

[0048] (1) Prepare a nanorod-shaped CeCu catalyst;

[0049] (2) Using the CeCu catalyst as a substrate, perform zinc loading to obtain a Zn / CeCu catalyst;

[0050] (3) Using the Zn / CeCu catalyst as a substrate, perform tin loading to obtain the Sn-Zn / CeCu catalyst.

[0051] In the above technical solution, a quaternary composite metal oxide catalytic system is constructed by combining SnO 2 , ZnO, CeO 2 and CuO to construct a Rochow-Müller reaction catalyst with more Cu + active sites, better performance in activating methyl chloride, and higher catalytic performance.

[0052] During the oxidation process of Ce, different phases can be formed at different pressures and temperatures. According to the valence state and possible oxidation states, its oxides are generally Ce 2 O 3 and CeO 2 , CeO2 Generally, it has a face-centered cubic structure. There are eight equivalent anions (O) around the cation (Ce), and each anion is coordinated by four cations to form a tetrahedron. Abnormal-valence CeO 2 -y can be formed during the reduction of Ce(IV) to Ce(III), and oxygen vacancies in the crystal structure are formed concomitantly.

[0053] Zn and its oxides are important cocatalysts for the Rochow-Müller reaction. Zn can act as a methylation group to enhance the adsorption of methyl chloride and accelerate the formation of Si-CH 3 . When Zn is introduced into the catalyst, the selectivity of dimethyldichlorosilane, the conversion rate of silicon powder, and the activity of the catalyst are all greatly improved.

[0054] Sn and its oxides are also important cocatalysts. Alone, Sn has low performance as an additive, but when used together with Zn, it has a synergistic effect. By increasing the depolymerization of Cu X Si and increasing the consumption of Cu X Si, more active sites are generated.

[0055] Preferably, in the step (1), the steps for preparing the CeCu catalyst are as follows: Completely dissolve Cu(NO 3 ) 2 ·3H 2 O and Ce(NO 3 ) 3 ·6H 2 O in ethanol, then add the NaOH solution, mix evenly and carry out a hydrothermal reaction. After the reaction ends, cool, filter, wash, dry, and calcine.

[0056] More preferably, the mass-volume ratio of Cu(NO 3 ) 2 ·3H 2 O, Ce(NO 3 ) 3 ·6H 2 O to ethanol is 1 - 1.5 g : 0.1 - 0.3 g : 10 - 15 mL;

[0057] The hydrothermal reaction is carried out at 150 - 200 °C for 18 - 24 h;

[0058] The drying temperature is 50 - 70 °C and the drying time is 8 - 12 h;

[0059] The calcination temperature is 400 - 600 °C and the calcination time is 2 - 6 h.

[0060] In the above technical solution, the Cu(NO3 ) 2 ·3H 2 O, Ce(NO 3 ) 3 ·6H 2 O and the mass-volume ratio of ethanol, because the content of absolute ethanol will affect the formation of CeCu nanorods, too much or too little absolute ethanol will make the CeCu nanorods not formed.

[0061] Preferably, the step of zinc loading in the step (2) is: uniformly disperse the CeCu catalyst into an ethanol aqueous solution, and then add Zn(NO 3 ) 2 ·6H 2 O solution, stir for 1 - 3 h, filter, wash, dry, and calcine.

[0062] More preferably, the mass ratio of the CeCu catalyst to Zn(NO 3 ) 2 ·6H 2 O is 1.0 - 1.5:0.1 - 0.2;

[0063] The volume ratio of water to ethanol in the ethanol aqueous solution is 1 - 2:1 - 2;

[0064] The drying temperature is 30 - 70 °C, and the drying time is 8 - 12 h;

[0065] The calcination temperature is 400 - 600 °C, and the calcination time is 2 - 6 h.

[0066] Preferably, the step of tin loading in the step (3) is: uniformly disperse the Zn / CeCu catalyst into an ethanol aqueous solution, and then add SnCl 4 ·5H 2 O solution, stir for 1 - 2 h, filter, wash, and dry.

[0067] More preferably, the mass ratio of the Zn / CeCu catalyst to SnCl 4 ·5H 2 O is 1.0 - 1.5:0.0001 - 0.0003;

[0068] The volume ratio of water to ethanol in the ethanol aqueous solution is 1 - 2:1 - 2;

[0069] The drying temperature is 60 - 80 °C, and the drying time is 8 - 12 h.

[0070] In the above technical solution, the present invention constructs Cu + / Ce 4+ , Cu 2+ / Ce3+ electron pairs and reduce carbon deposition. Incorporate SnO 2 , ZnO, CeO 2 and CuO to construct a Rochow-Müller reaction catalyst with more Cu + active sites, better performance in activating chloromethane, and higher catalytic performance. CuO is a commonly used industrial catalyst, which has a large specific surface area, small particle size, appropriately exposed crystal planes, and is easy to prepare and store. However, the conversion rate and selectivity of a single CuO catalyst are poor; ZnO is a commonly used promoter in the Rochow-Müller reaction, which can improve the methylation of chloromethane and prevent carbon deposition of chloromethane at a certain temperature; SnO 2 and its oxides are also commonly used as co-catalysts in the Rochow-Müller process. Incorporating Sn into the CuO lattice has been proven to be an effective strategy to improve catalytic activity. Sn can diffuse to the active catalyst interface through grain boundaries to accelerate the depolymerization of the Cu X Si active phase, increase the consumption of Cu X Si to generate more active center numbers, and thus improve the selectivity of M2. CeO 2 has good oxygen vacancies and excellent oxygen storage performance, which can enable the CuO catalyst to generate more Cu + , and activate the lattice oxygen to form more oxygen vacancies, promoting the generation of active intermediates. Incorporate SnO 2 , ZnO, CeO 2 and CuO to successfully increase the content of Cu + . The methylation of chloromethane is easier to carry out, avoiding the problems of insufficient activity of a single Cu catalyst and carbon deposition of chloromethane. The combination of Ce and Cu enables the formation of Cu + / Ce 4+ , Cu 2+ / Ce 3+ electron pairs, which can promote the formation of Cu + active centers. Through the formation of active centers, active intermediate Cu X Si is formed more effectively, greatly improving the performance of the Rochow-Müller reaction. Finally, this Sn-Zn / CuCe catalytic system realizes the simple synthesis of materials, has low cost, simple operation, and has the characteristics of high conversion rate, high selectivity, and good stability.

[0071] Example 1.

[0072] The specific operation steps are as follows:

[0073] (1) Prepare nanorod-shaped copper-cerium catalyst (CuCe)

[0074] Dissolve 1.208 g of Cu(NO3 ) 2 ·3H 2 O and 0.2523 g Ce(NO 3 ) 3 ·6H 2 O were dissolved in 10 mL of absolute ethanol, and stirred at 500 r / min magnetically until completely dissolved. Subsequently, 100 mL of NaOH (1.0 M) was added, stirred for 10 min, transferred to a 200 mL Teflon-lined hydrothermal autoclave for hydrothermal reaction, heated at 150 °C for 24 h; after the reaction cooled, filtered, washed with ultrapure water and absolute ethanol, dried at 50 °C for 10 h, and calcined in a muffle furnace at 500 °C for 6 h to obtain the CuCe composite material, namely the CuCe catalyst.

[0075] (2) Preparation of zinc-loaded nanorod-shaped copper-cerium catalyst (Zn / CuCe)

[0076] 1.0 g of the CuCe composite material was dispersed into 100 mL of an ethanol aqueous solution (ethanol v: water v = 1:1), and 0.1462 g of Zn(NO 3 ) 2 ·6H 2 O was dissolved in 20 mL of ultrapure water, slowly dropped into the above solution, stirred for 3 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 50 °C for 10 h, and calcined in a muffle furnace at 500 °C for 6 h to obtain the Zn / CuCe catalyst.

[0077] (3) Preparation of tin- and zinc-loaded nanorod-shaped copper-cerium catalyst (Sn-Zn / CuCe)

[0078] 1 g of the Zn / CuCe composite material was dispersed into 100 mL of an ethanol aqueous solution (ethanol v: water v = 1:1), and 0.0001 g of SnCl 4 ·5H 2 O was dissolved in 20 mL of ultrapure water, slowly dropped into the above solution, stirred for 2 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 60 °C for 8 h to obtain the Sn-Zn / CuCe catalyst.

[0079] Example 2.

[0080] The specific operation steps are as follows:

[0081] (1) Preparation of nanorod-shaped copper-cerium catalyst (CuCe)

[0082] 1.208 g of Cu(NO 3 ) 2 ·3H 2 O and 0.1262 g of Ce(NO 3 ) 3 ·6H2 O was dissolved in 10 mL of absolute ethanol and stirred magnetically at 500 r / min until completely dissolved. Subsequently, 100 mL of NaOH (1.0 M) was added and stirred for 10 min. Then it was transferred to a 200 mL polytetrafluoroethylene-lined hydrothermal autoclave for hydrothermal reaction at a hydrothermal temperature of 150 °C for 24 h. After the reaction cooled, it was filtered, washed with ultrapure water and absolute ethanol, dried at 60 °C for 8 h, and calcined in a muffle furnace at 400 °C for 8 h to obtain a CuCe composite material, namely the CuCe catalyst.

[0083] (2) Preparation of zinc-loaded nanorod-shaped copper-cerium catalyst (Zn / CuCe)

[0084] 1 g of the CuCe composite material was dispersed in 100 mL of an ethanol-water solution (ethanol v: water v = 1:1). 0.1827 g of Zn(NO 3 ) 2 ·6H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution, stirred for 2 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 60 °C for 8 h, and calcined in a muffle furnace at 400 °C for 4 h to obtain the Zn / CuCe catalyst.

[0085] (3) Preparation of tin- and zinc-loaded nanorod-shaped copper-cerium catalyst (Sn-Zn / CuCe)

[0086] 1 g of the Zn / CuCe composite material was dispersed in 100 mL of an ethanol-water solution (ethanol v: water v = 1:1). 0.0003 g of SnCl 4 ·5H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution, stirred for 2 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 60 °C for 8 h to obtain the Sn-Zn / CuCe catalyst.

[0087] Example 3.

[0088] The specific operation steps are as follows:

[0089] (1) Preparation of nanorod-shaped copper-cerium catalyst (CuCe)

[0090] 1.0 g of Cu(NO 3 ) 2 ·3H 2 O and 0.10 g of Ce(NO 3 ) 3 ·6H 2O was dissolved in 11 mL of absolute ethanol and stirred magnetically at 500 r / min until completely dissolved. Subsequently, 100 mL of NaOH (1.0 M) was added and stirred for 10 min. Then it was transferred to a 200 mL Teflon-lined hydrothermal reactor for hydrothermal reaction at a hydrothermal temperature of 200 °C for 18 h. After the reaction cooled, it was filtered, washed with ultrapure water and absolute ethanol, dried at 60 °C for 10 h, and calcined in a muffle furnace at 500 °C for 6 h to obtain the CuCe composite material, namely the CuCe catalyst.

[0091] (2) Preparation of zinc-loaded nanorod-shaped copper-cerium catalyst (Zn / CuCe)

[0092] 1.1 g of the CuCe composite material was dispersed in 100 mL of an ethanol-water solution (ethanol v: water v = 2:1.5). 0.10 g of Zn(NO 3 ) 2 ·6H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution, stirred for 1 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 30 °C for 12 h, and calcined in a muffle furnace at 600 °C for 2 h to obtain the Zn / CuCe catalyst.

[0093] (3) Preparation of tin- and zinc-loaded nanorod-shaped copper-cerium catalyst (Sn-Zn / CuCe)

[0094] 1.1 g of the Zn / CuCe composite material was dispersed in 100 mL of an ethanol-water solution (ethanol v: water v = 2:1.5). 0.0002 g of SnCl 4 ·5H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution, stirred for 1 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 30 °C for 12 h to obtain the Sn-Zn / CuCe catalyst.

[0095] Example 4.

[0096] The specific operation steps are as follows:

[0097] (1) Preparation of nanorod-shaped copper-cerium catalyst (CuCe)

[0098] 1.5 g of Cu(NO 3 ) 2 ·3H 2 O and 0.3 g of Ce(NO 3 ) 3 ·6H 2O was dissolved in 15 mL of absolute ethanol and stirred magnetically at 500 r / min until completely dissolved. Subsequently, 100 mL of NaOH (1.0 M) was added, and the mixture was stirred for 10 min. Then it was transferred to a 200 mL hydrothermal autoclave with a polytetrafluoroethylene inner lining for hydrothermal reaction. The hydrothermal temperature was 180 °C, and it was heated for 20 h. After the reaction cooled down, it was filtered, washed with ultrapure water and absolute ethanol, dried at 70 °C for 12 h, and calcined in a muffle furnace at 600 °C for 7 h to obtain the CuCe composite material, namely the CuCe catalyst.

[0099] (2) Preparation of zinc-loaded nanorod-shaped copper-cerium catalyst (Zn / CuCe)

[0100] 1.5 g of the CuCe composite material was dispersed in 100 mL of an ethanol aqueous solution (ethanol v: water v = 1.5:2). 0.2 g of Zn(NO 3 ) 2 ·6H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution. The mixture was stirred for 2 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 70 °C for 10 h, and calcined in a muffle furnace at 400 °C for 6 h to obtain the Zn / CuCe catalyst.

[0101] (3) Preparation of tin- and zinc-loaded nanorod-shaped copper-cerium catalyst (Sn-Zn / CuCe)

[0102] 1.5 g of the Zn / CuCe composite material was dispersed in 100 mL of an ethanol aqueous solution (ethanol v: water v = 1.5:2). 0.0003 g of SnCl 4 ·5H 2 O was dissolved in 20 mL of ultrapure water and slowly dropped into the above solution. The mixture was stirred for 1.5 h, filtered, washed with ultrapure water and absolute ethanol, dried in an oven at 70 °C for 10 h to obtain the Sn-Zn / CuCe catalyst.

[0103] Example 5.

[0104] Method: The morphologies of the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1 were characterized by scanning electron microscopy. The nanoparticles of the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst in Example 1 were dispersed in ethanol on a clean copper mesh, dried, and then tested by scanning electron microscopy.

[0105] Result: As Figure 1 shown, the left figure is the scanning electron micrograph of the CuCe catalyst in step (1) of Example 1. It can be seen that there are tiny granular objects on its surface, proving that cerium is loaded onto the surface of copper.

[0106] The middle figure is the scanning electron microscope of the Zn / CuCe catalyst in Example 1, proving that the loading of zinc does not significantly change the morphology of the catalyst.

[0107] The right figure is the Sn-Zn / CuCe figure in Example 1. It can be clearly seen that the overall material is rod-shaped with a small amount of particles on the surface, proving that Ce is successfully loaded onto the surface of CuO, and the loading of Zn and Sn also does not significantly change the morphology of the catalyst, which is beneficial to improving the activity of the catalyst.

[0108] Example 6.

[0109] Method: The morphologies of the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1 were characterized by transmission electron microscopy. The CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe nanoparticles in Example 1 were dispersed in ethanol on a clean copper grid and dried before high-resolution transmission.

[0110] Result: As Figure 2 shown, the left figure is the lattice fringe of the CuCe catalyst. It can be seen that the lattice fringe of the nanorod-shaped copper-cerium catalyst is 0.27 nm, exposing the (110) crystal plane of Cu. The middle is the TEM and lattice fringe of the Zn / CuCe catalyst. It can be seen that the lattice fringe is still 0.27 nm, exposing the (110) crystal plane of CuO. The incorporation of Zn does not change the crystal plane of the catalyst. The right figure is the TEM and lattice fringe of the Sn-Zn / CuCe catalyst. It can be seen that the lattice fringe is still 0.27 nm after the incorporation of Sn, and the exposed is still the (110) crystal plane of CuO. The incorporation of Sn also does not affect the change of the crystal plane.

[0111] Example 7.

[0112] Method: The CuO catalyst and the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1 were characterized by XRD.

[0113] Result: As Figure 3As shown, the peak values of the diffraction peaks exhibited by the copper-cerium catalyst at 32.5°, 35.5°, 38.7°, 48.7°, 61.5°, 66.2°, and 68.1° respectively belong to (110), (11-1), (111), (20-2), (020), (202), (11-3), (31-1), (220), (311), (22-2), corresponding to the PDF 48-1548 standard card. The diffraction peaks of the zinc-loaded copper-cerium catalyst are the same as those of the copper-cerium diffraction peaks, and no diffraction peaks of other species appear, which proves that Zn is relatively uniformly dispersed and has a lower diffraction peak intensity compared to the copper-cerium catalyst, indicating that the introduction of zinc leads to a decrease in the crystallinity of CuO. Zinc may enter the CuO lattice in the form of atoms, thus being more conducive to the formation of Cu + active sites.

[0114] Example 8.

[0115] Method: XPS characterization was performed on the CuO catalyst and the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1.

[0116] Results: As Figure 4 shown, the main peak and shoulder peak of Cu 2p of Cu appear near 934.6 eV and 932.5 eV respectively, belonging to Cu 3 / 2 and Cu 2+ / Cu 0 / Cu + , and the appearance of two satellite peaks accompanying the Cu 2p peak means the coexistence of -2 valence and +1 / 0 valence in the catalyst, and the copper in the +2 valence form is the main body. Compared with pure CuO, CuCe contains more Cu+, and compared with CuCe, the content of Cu+ is more in the Zn / CuCe catalyst. After loading Sn, the content of Cu+ further increases. In order to maintain charge conservation, more defects will be formed, increasing the electron density on Cu and improving the catalytic performance. Therefore, it can be proved that the incorporation of Ce, Zn, and Sn can improve the surface active sites.

[0117] Example 9.

[0118] Method: H 2 -TPR characterization was performed on the CuO catalyst and the CuCe catalyst, Zn / CuCe catalyst, and Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1.

[0119] Results: As Figure 5 shown, the H 2The reduction temperature of TPR is 265.91 °C. After loading zinc, the reduction temperature decreases to 202.37 °C. After incorporating zinc, the reduction temperature decreases, and the required temperature for reduction is lower, making it easier to participate in redox reactions. After incorporating tin, the reduction temperature decreases to 202.02 °C, and the reduction temperature further decreases, making it easier to undergo redox reactions to generate reactive intermediates.

[0120] Example 10.

[0121] Method: Perform performance tests on CuO catalysts, the CuCe catalyst prepared in Example 1, Zn / CuCe catalysts, and Sn-Zn / CuCe catalyst nanoparticles.

[0122] Catalytic evaluation operation process: Put 10.0 g of silicon powder and 0.5 g of catalyst into an agate mortar, stir and mix well to form a catalyst body, and then load it into a fixed-bed reaction tube. First, install a layer of quartz wool at the bottom to fix the catalyst body. After pouring in the catalyst body, install another layer of quartz wool to fix the reaction catalyst body. Then pour in a layer of quartz sand to prevent the gas flow from blowing the catalyst body away. Install the fixed-bed reaction tube into the fixed bed. First, pass N 2 (25 mL / min) to purge the reaction system for 30 min. Then, under an N 2 atmosphere, raise the temperature to 325 °C within 1 h. Subsequently, close N 2 , and pass MeCl (25 mL / min) and react for 24 h; the reaction product is cooled to a liquid phase by a condenser, and the cooling temperature is -5 °C; the cooled liquid is collected with toluene and quantitatively analyzed by gas chromatography. The products mainly include M1, M2, M3, H1M, H2M, LBR, and HBR.

[0123] Calculate the selectivity of each product using the area percentage method. The calculation methods for the selectivity of M2 and the conversion rate of Si are as follows:

[0124] Selectivity of M2:

[0125] Conversion rate of Si:

[0126] Among them: m in the formula for the selectivity of M2 represents the mass of different products, and m Si，反应前 and m Si反应后 in formula (2) represent the mass of the catalyst body before and after the reaction.

[0127] Results: As Figure 6As shown, the experimental results show that the left figure is the M2 selectivity of the catalyst, the middle figure is the conversion rate of Si powder, and the right figure is the yield of M2. It can be seen that Ce, Zn, and Sn all have a certain impact on the improvement of the performance of the copper-based catalyst. The zinc-loaded copper-cerium catalyst has a relatively good conversion rate of Si powder, with a conversion rate of Si powder of 36.6%, an M2 selectivity of 85.3%, and an M2 yield reaching 31.2%. This means that the doping of Ce and the loading of Zn can improve the reaction activity of CuO. After further loading Sn, although the M2 selectivity does not increase significantly, the conversion rate of Si powder further increases to 42.2%, the selectivity of M2 also increases to 86.9%, and the yield of M2 also increases from 19.7% at the beginning to 36.7%, more effectively activating methyl chloride gas and generating active intermediates, thereby generating more M2 products.

[0128] Example 11.

[0129] Method: The M2 selectivity of the CuO catalyst, the CuCe catalyst, the Zn / CuCe catalyst, and the Sn-Zn / CuCe catalyst nanoparticles prepared in Example 1 was tested during the preparation process.

[0130] Results: As Figure 7 shown, the experimental results show that as the reaction proceeds, the zinc-loaded copper-cerium catalyst has better stability. The initial M2 selectivity of the copper oxide catalyst is 77.0%, and the M2 selectivity continuously decreases during the reaction, decreasing to 35.5% after 48 h. After doping with cerium, the selectivity after 48 h increases to 44.7%, and after loading zinc, the M2 selectivity after 48 h of reaction is 67.4%. After further doping with tin, the stability of the selectivity is further improved, and the M2 selectivity after 48 h also increases from 35.5% of the CuO catalyst to 71.4%. This shows that the addition of cerium, zinc, and tin can improve the stability of the catalyst.

[0131] In the present invention, the entire reaction process has a simple flow, a small amount of added metal, high economic efficiency, strong universality, is easy to be scaled up for industrial production, and good stability is also one of the advantages of the present invention. First, by regulating the reactant ratio and reaction conditions, nanorod-shaped copper-cerium catalysts are successfully prepared. Compared with copper oxide, there are more active sites on the surface and more oxygen vacancies are generated. At the same time, using this as a substrate, zinc is loaded to prepare a zinc-loaded copper-cerium catalyst, which has a lower reduction active site temperature and more active sites.

[0132] The present invention innovatively adopts a three-step synthesis strategy and successfully develops a high-performance nanorod-shaped Rochow-Müller reaction catalyst. The nanorod-shaped copper-cerium catalyst is synthesized by a hydrothermal method, introducing cerium element to form Cu + / Ce4+ , Cu 2+ / Ce 3+ electron pairs not only promote the generation of active sites but also significantly enhance the oxygen activation ability, thus greatly improving the catalytic activity of the catalyst. Zinc is loaded on the surface of the nanorod-shaped copper-cerium catalyst by the impregnation method. The addition of zinc can significantly improve the activation efficiency of methyl chloride, promote the generation of methyl radicals, and enhance the reaction with reactive intermediates, thereby increasing the production rate of M2. At the same time, zinc can also prolong the survival time of reactive intermediates, enabling more silicon powder to participate in the reaction and improving the conversion rate of silicon powder. The impregnation method is used again to load a small amount of tin onto the catalyst surface, further improving the performance of the catalyst. The presence of tin promotes the depolymerization of the Cu 3 -Si active phase, increases the consumption of the active phase, thus generating more active centers and further improving the selectivity of M2.

[0133] Through a simple synthesis method, low cost, and doping with a small amount of metal, the present invention successfully synthesizes a new type of copper-based catalyst. This catalyst not only has excellent catalytic performance but also achieves high conversion and high selectivity for the Rochow-Müller reaction, while improving the reaction stability and ensuring good M2 selectivity of the catalyst over a long period. These innovations give the present invention significant advantages and broad application prospects in the field of catalysts.

[0134] The above description is only a preferred embodiment of the embodiments of the present invention and does not impose any form of limitation on the embodiments of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the embodiments of the present invention still fall within the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a Sn-Zn / CeCu catalyst for Rochow-Müller reaction, characterized in that: The following steps are involved: (1) Preparation of nanorod-shaped CeCu catalysts; (2) using the CeCu catalyst as a substrate to load zinc to obtain a Zn / CeCu catalyst; (3) Using the Zn / CeCu catalyst as a substrate, tin is loaded to obtain the Sn-Zn / CeCu catalyst.

2. The preparation method according to claim 1, characterized in that: In the step (1), the step of preparing the CeCu catalyst is: after completely dissolving Cu(NO3)2·3H2O and Ce(NO3)3·6H2O in ethanol, adding NaOH solution, mixing evenly and then conducting a hydrothermal reaction, after the reaction is completed, cooling, filtering, washing, drying and roasting.

3. The preparation method according to claim 2, characterized in that: The mass volume ratio of Cu(NO3)2·3H2O, Ce(NO3)3·6H2O and ethanol is 1-1.5g:0.1-0.3g:10-15mL; The hydrothermal reaction is at 150-200°C and the reaction time is 18-24h; The drying temperature is 50-70°C and the drying time is 8-12h; The calcination time is 400-600°C and the calcination time is 6-8h.

4. The preparation method according to claim 1, characterized in that: The zinc loading step in step (2) is as follows: uniformly dispersing the CeCu catalyst into an ethanol aqueous solution, adding a Zn(NO3)2·6H2O solution, stirring for 1-3 hours, filtering, washing, drying, and calcining.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the CeCu catalyst to Zn(NO3)2·6H2O is 1.0-1.5:0.1-0.2; The volume ratio of water to ethanol in the ethanol aqueous solution is 1-2:1-2; The drying temperature is 30-70°C and the drying time is 8-12h; The calcination time is 400-600°C and the calcination time is 2-6h.

6. The preparation method according to claim 1, characterized in that: The tin loading step in step (3) is as follows: the Zn / CeCu catalyst is uniformly dispersed in an ethanol aqueous solution, and then a SnCl4·5H2O solution is added, stirred for 1-2 hours, filtered, washed, and dried.

7. The preparation method according to claim 6, characterized in that: The mass ratio of the Zn / CeCu catalyst to SnCl4·5H2O is 1.0-1.5:0.0001-0.0003; The volume ratio of water to ethanol in the ethanol aqueous solution is 1-2:1-2; The drying temperature is 30-70°C and the drying time is 8-12h.

8. A Sn-Zn / CeCu catalyst for Rochow-Müller reaction, characterized in that: The method is prepared by any one of claims 1 to 7.

9. Use of the Sn-Zn / CeCu catalyst according to claim 8 in Rochow-Müller reaction.

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