A nickel-based bimetallic catalyst, its preparation method and application

Abstract

The present invention provides a preparation method of a nickel-based bimetallic catalyst, comprising the following steps: (1) Dissolve a soluble nickel salt in water, load it onto a carrier, and obtain a catalyst precursor after drying, calcination, and reduction treatments; (2) Impregnate and load a soluble promoter salt solution onto the catalyst precursor prepared in step (1), and obtain the desired nickel-based bimetallic catalyst after aging, drying, calcination, and reduction; wherein, the soluble promoter salt is selected from soluble promoter salts containing one or several components of Ag, Au, Ru, Pt, or Mo; the carrier is composed of one or several of silica, titanium dioxide, cerium dioxide, or zirconium dioxide. Using the nickel-based bimetallic catalyst prepared by the above preparation method for the reaction of catalytic hydrogenation of dimethyl oxalate to methyl glycolate can achieve high-efficiency and stable catalytic activity under conditions of a relatively high liquid hourly space velocity and a relatively low hydrogen-to-ester ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst chemistry, and particularly relates to a nickel-based bimetallic catalyst for hydrogenating oxalate to methyl glycolate, a preparation method thereof, and an application thereof. Background Art

[0002] Methyl glycolate (MG) is an important organic chemical intermediate. Since it has α-H, hydroxyl, and ester functional groups in its molecule, it has both the chemical properties of alcohols and esters and is widely used in the fields of chemicals, pharmaceuticals, fragrances, and polymer materials. As an intermediate raw material, MG can be used to prepare a series of important downstream products, such as hydrolysis to produce glycolic acid, hydrogenation to produce ethylene glycol, carbonylation to produce dimethyl malonate, ammonolysis to produce glycine, and oxidative dehydrogenation to produce methyl glyoxylate. At present, the main industrial synthesis methods of methyl glycolate are as follows: formaldehyde carbonylation method, methyl formate coupling method, chloroacetic acid esterification method, and the hydrogenation route after preparing dimethyl oxalate (DMO) from syngas. Considering the relative economy and environmental protection of the syngas route and the dominant position of coal resources in China's energy structure, the process method of hydrogenating DMO to MG has better industrial application prospects and economic benefits.

[0003] Currently, copper-based catalysts and silver-based catalysts are the main catalysts used in the DMO-to-MG system. For example, in CN114054041A, by adjusting the atomic ratio of the main active component Cu to the promoters (Pt, Pd, Au, Rh, Ag, and Ru) in the catalyst and the corresponding raw material ratio, the switching between MG and EG in the DMO hydrogenation product is achieved. After adjusting the atomic ratio of noble metals such as Rh and Ru to Cu, under the optimal conditions, the DMO conversion rate can be close to complete conversion, and the MG selectivity reaches 99%; in CN101954288A, the researchers used silica as the carrier, Cu as the main active component, and simultaneously added noble metal Ag and another metal promoter. On the 20% Cu-12% Ag-0.2% Pt / SiO2 catalyst in the optimal Example 17, a DMO conversion rate of 94.5% and an MG selectivity of 91.2% can be obtained; in CN 108499564A, the researchers adopted a two-step method to synthesize a modified Cu catalyst. First, a Cu catalyst precursor was prepared by the ammonia evaporation method. After being refluxed with a toluene solution of trichloromethylsilane or dichloromethylsilane and impregnated with an ethanol solution of ammonium fluoride, the soluble salt solution of the promoter was loaded onto the Cu catalyst precursor by the impregnation method. On the 30% Cu-3% Ni / SiO2 catalyst in the best Example 5, the DMO conversion rate was 88.3%, and the MG selectivity was 93.8%. It can be seen that on the Cu-based catalyst, it is usually necessary to add a certain amount of noble metal promoters, such as Ag, or change the catalyst preparation method to improve its selectivity for MG. However, these methods are limited in the process promotion of DMO hydrogenation to MG because their own preparation processes are numerous and complex, which will increase the catalyst preparation cost. On the other hand, due to the weak ability of Ag to activate hydrogen, silver-based catalysts often require a high Ag loading and promoters or a method to change their carrier structure to improve Ag dispersion to achieve a high DMO conversion rate. For example, in CN104492429A, the researchers used titanium dioxide, carbon carrier, or a combination of both as the carrier, and loaded an Ag / CNT catalyst (>10 wt.%) by the impregnation method to obtain an MG yield of 96.4%; CN 113368867A discloses an ultrasonic-assisted impregnation method for preparing a silver-based catalyst for DMO hydrogenation to MG. Its main active components are Ag and Mo oxides (2-35 wt.%), and the promoters are one or more of Fe, K, Na, Pd, Pt, Ru, Au, Ba, Cu, Mg,, Ni, Co, Mn, Zn, Ca, Ce, La, Zr, Al, Cr. Under the optimal conditions, a DMO conversion rate of 99.6% and an MG selectivity of 89.9% can be obtained.In CN112387306 A, the researchers first prepared mesoporous silica microspheres, and after amination, 3 wt.% of Ag was loaded by in-situ reduction method. On the optimal catalyst (Example 12), a 97.2% yield of MG could be obtained and DMO could be completely converted. However, this method has a too complex process route. The preparation of the carrier mesoporous silica microspheres and the amination process are time-consuming and use a large amount of organic solvents. Although the loading amount of Ag can be effectively reduced, its process cost is still high, which is not conducive to its application in the actual industry. CN 107442113 discloses a hierarchical porous nanoflower structure Ag catalyst for the hydrogenation of DMO to MG. By impregnating and loading Ag onto Ti-doped nanospheres KCC-1, 10Ag / Ti-KCC-1 (10 wt.%) can be obtained, achieving a 98.6% conversion rate of DMO and 94.3%. However, on the one hand, the loading amount of Ag in this method is relatively high, and on the other hand, the preparation process of the carrier Ti-KCC-1 is complex, which is not conducive to practical application. Generally speaking, the high preparation cost of Ag-based catalysts limits their application in the process of hydrogenating DMO to MG.

[0004] In recent years, Ni-based catalysts have received extensive attention due to their high mechanical strength, good catalytic activity, low price, etc. For example, in reactions such as carbon dioxide methanation, Ni-based catalysts have obvious advantages (Applied Catalysis B: Environmental 297 (2021) 120401). Some researchers have begun to introduce Ni-based catalysts into the process of hydrogenating DMO to MG. However, due to the poor activity of single Ni catalysts during the hydrogenation of DMO (Chemical Communication., 2016, 52, 2569), most of the current Ni-based catalyst research in this field focuses on the preparation of NiP amorphous alloy catalysts. For example, CN 105251521A discloses a supported NixPy catalyst prepared by an impregnation method, and the selected support is at least one of silica, titanium dioxide, zinc oxide, and activated carbon. The best performance can achieve 100% DMO conversion and 79.4 MG selectivity. However, for the catalyst prepared by this method, strict requirements are imposed on the heating rate during the temperature-programmed reduction treatment, and toxic gas PH3 will be generated during the reduction process of the catalyst, which not only leads to the P / Ni ratio in the raw materials during preparation being greater than the stoichiometric ratio but also brings certain safety hazard problems. Similarly, in CN 111921547A, the researchers used co-precipitation precipitation and secondary impregnation or temperature-programmed reduction methods to prepare catalysts containing different components of Ni and NiP. However, the NiP alloy will undergo a phase change during the reaction process, thus affecting the performance of the catalyst (ACS Appl. Mater. Interfaces 2019, 11, 37635 - 37643), so it is not conducive to the popularization of this method. In addition, CN107694584A discloses a method of first hydrothermally growing a nickel oxalate or nickel hydroxide crystal layer in situ on a skeleton substrate made of metal or silicon carbide (the selected metal is any one of nickel, stainless steel, iron-chromium-aluminum, brass, and cupronickel), and then obtaining a NiP catalyst through phosphating treatment. In the optimal Example 1, 99.1% DMO conversion and 95.6% MG selectivity can be achieved. However, this method also involves highly toxic PH3 gas during the phosphating treatment or reduction process, and the preparation process is complex and time-consuming, which is not conducive to its practical application. CN 109201059 B uses a nickel-based catalyst with a general formula of xNiO-yMO / ZT. When it is applied to the reaction of hydrogenating DMO to MG, the DMO conversion rate can reach 99%, but the selectivity of MG is only 75%. Moreover, during the preparation process, the preparation process of the nickel oxide-based catalyst precursor is complex and time-consuming, which is not conducive to its practical promotion.

[0005] In summary, in the reaction process of DMO hydrogenation to MG, there is still a need to develop a catalyst with low preparation cost, simple and safe preparation method, high DMO conversion rate, and good MG selectivity. Summary of the Invention

[0006] Aiming at the above problems and deficiencies existing in the prior art for the preparation of DMO hydrogenation to MG catalyst, the purpose of the present invention is to provide a nickel-based bimetallic catalyst for DMO hydrogenation to MG, which is green, clean, low-cost, and easy to prepare, and can obtain stable and high DMO conversion rate and MG selectivity.

[0007] The present invention provides a preparation method of a nickel-based bimetallic catalyst, and the specific technical scheme adopted includes the following steps:

[0008] (1) After dissolving the soluble nickel salt in water, it is loaded onto the carrier, and after drying, calcination, and reduction treatments, a catalyst precursor is obtained;

[0009] (2) The soluble promoter salt solution is impregnated and loaded onto the catalyst precursor prepared in step (1), and after aging, drying, calcination, and reduction, the required nickel-based bimetallic catalyst is obtained;

[0010] Among them, the soluble promoter salt is selected from soluble promoter salts containing one or several components of Ag, Au, Ru, Pt, or Mo;

[0011] The carrier is composed of one or several of silica, titanium dioxide, cerium dioxide, or zirconium dioxide.

[0012] In the preparation method of the nickel-based bimetallic catalyst of the present invention, after the prepared catalyst precursor is subjected to heat treatment of calcination and reduction, its surface has abundant interfacial sites; then, through the impregnation method, under the anchoring effect of the surface sites of the catalyst precursor, the metal ions of the promoter salt are loaded onto the catalyst precursor, and finally, a nickel-based bimetallic catalyst with a low loading amount of the promoter is prepared through further heat treatment.

[0013] The present invention is further preferably that in step (1), the calcination temperature is 350 - 650 °C, and the calcination time is 2 - 10 h.

[0014] The present invention is further preferably that in step (1), the reduction temperature is 300 - 650 °C, and the reduction time is 3 - 24 h.

[0015] The present invention is further preferably that in step (1), the soluble nickel salt is dissolved in water and loaded onto the carrier by the sol-gel method, and the preparation of the catalyst precursor includes the following steps:

[0016] (i) The soluble nickel salt is dissolved in deionized water and a certain proportion of absolute ethanol to prepare solution A;

[0017] (ii) Take an appropriate amount of the carrier precursor and mix it with deionized water to prepare solution B;

[0018] (iii) Add solution A to solution B, react at 40 - 120 °C for 4 - 48 h, after aging, drying, and calcination, reduce it at 300 - 650 °C in hydrogen for 3 - 24 h to obtain the catalyst precursor;

[0019] Among them, the carrier precursor is selected from one or more of tetraethyl orthosilicate, sodium silicate, tetrabutyl titanate, cerium nitrate, or zirconium nitrate.

[0020] The present invention is further preferably that in step (i), the molar ratio of the soluble nickel salt to absolute ethanol is 1:1 - 3.5.

[0021] The present invention is further preferably that in step (1), the soluble nickel salt is dissolved in water by the precipitation method and then loaded onto the carrier. The preparation of the catalyst precursor includes the following steps:

[0022] (i) Dissolve the soluble nickel salt and the precipitant in deionized water to prepare a homogeneous solution;

[0023] (ii) After mixing the carrier with an appropriate amount of water, mix it with the homogeneous solution prepared in step (i), react at 70 - 150 °C for 4 - 48 h, filter and wash the precipitate;

[0024] (iii) After aging, drying, and calcination treatment of the obtained colloid, reduce it at 300 - 650 °C in hydrogen for 3 - 24 h to obtain the catalyst precursor;

[0025] Among them, the precipitant is selected from one or more of ammonia water, urea, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0026] The present invention is further preferably that in step (1), after loading the soluble nickel salt onto the carrier, it is aged at 20 - 40 °C for 4 - 14 h, dried at 70 - 120 °C for 4 - 14 h, calcined at 350 - 650 °C in air for 2 - 10 h, and then subjected to reduction treatment to obtain the catalyst precursor.

[0027] The present invention is further preferably that a soluble nickel salt is dissolved in water and loaded onto a support by a precipitation method. In the corresponding preparation method of the catalyst precursor, the support in step (ii) is selected from one or more of silica sol, fumed silica, titanium dioxide, zirconium dioxide, and cerium dioxide. Further, the support is composed of fumed silica and any one of titanium dioxide, zirconium dioxide, or cerium dioxide, and the mass ratio of the fumed silica to any one of titanium dioxide, zirconium dioxide, or cerium dioxide is (0.8 - 5.0):1. Further still, the support is composed of fumed silica and zirconium dioxide, and the mass ratio of fumed silica to zirconium dioxide is (2.0 - 5.0):1.

[0028] The present invention is further preferably that in step (2), the calcination conditions are: temperature 350 - 650 °C, time 2 - 8 h; the reduction conditions are: temperature 200 - 650 °C, time 2 - 12 h.

[0029] The present invention is further preferably that in step (2), after impregnating and loading the soluble promoter salt solution onto the catalyst precursor prepared in step (1), it is aged at 20 - 40 °C for 4 - 14 h, dried at 70 - 120 °C for 4 - 14 h, calcined at 350 - 650 °C for 2 - 8 h, and reduced at 200 - 650 °C for 2 - 12 h to obtain the nickel-based bimetallic catalyst.

[0030] The soluble nickel salt described in the present invention is a common soluble nickel salt, preferably one or several of nickel nitrate, nickel acetate, and nickel chloride.

[0031] The present invention is further preferably that in the prepared nickel-based bimetallic catalyst, the content of nickel is 3.0 - 20 wt.%, the content of the promoter metal is 0.01 - 1.0 wt.%, and the rest is the support.

[0032] The present invention provides a nickel-based bimetallic catalyst prepared according to the above preparation method of the nickel-based bimetallic catalyst.

[0033] The present invention also provides an application of the above nickel-based bimetallic catalyst in the reaction of hydrogenating dimethyl oxalate to methyl glycolate.

[0034] The present invention is further preferably that the nickel-based bimetallic catalyst is loaded into a fixed-bed reactor for the reaction of hydrogenating dimethyl oxalate to methyl glycolate. The reaction conditions are: reaction temperature 170 - 280 °C, reaction pressure 1 - 3 MPa, liquid hourly space velocity of DMO 0.1 - 3.0 h -1 , and the molar ratio of hydrogen to dimethyl oxalate is 30:1 - 300:1.

[0035] To reduce the impact of the oxidation of the prepared nickel-based bimetallic catalyst in air on the subsequent hydrogenation reaction, before using the catalyst in the reaction of hydrogenating dimethyl oxalate to methyl glycolate, the catalyst is usually first subjected to in-situ hydrogen reduction in the reaction device at a reduction temperature of 200-650 °C and a reduction time of 2-12 h; then the reaction of hydrogenating dimethyl oxalate to methyl glycolate is carried out.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In the preparation method of the nickel-based bimetallic catalyst of the present invention, by preparing a precursor of nickel having a stable strong interaction with the carrier, after heat treatment of calcination in air and hydrogen reduction, its surface has abundant interfacial sites. By using the anchoring effect of the interfacial sites on the promoter salt ions, a nickel-based bimetallic catalyst with a low loading amount of promoter can be prepared, greatly reducing the preparation cost of the catalyst.

[0038] (2) When the nickel-based bimetallic catalyst prepared by the present invention is used in the reaction of hydrogenating dimethyl oxalate to methyl glycolate, it has excellent catalytic activity and selectivity for methyl glycolate, and can achieve a dimethyl oxalate conversion rate > 99% and a methyl glycolate selectivity > 99%.

[0039] (3) When the nickel-based bimetallic catalyst prepared by the present invention is used in the reaction of hydrogenating dimethyl oxalate to methyl glycolate, it can achieve high-efficiency and stable catalytic activity under conditions of a relatively high liquid hourly space velocity and a relatively low hydrogen-to-ester ratio, and still exhibits high catalytic activity and selectivity after long-term operation. Description of the Drawings

[0040] Figure 1 It is the stability test result of the nickel-based bimetallic catalyst in Example 3. Detailed Embodiments

[0041] The present invention will be further described below through examples. The following examples are only used to illustrate the present invention, but do not limit the scope of implementation of the present invention.

[0042] The present invention provides a preparation method of a nickel-based bimetallic catalyst, including the following steps:

[0043] (1) After dissolving a soluble nickel salt in water, it is loaded onto a carrier, and after drying, calcination, and reduction treatments, a catalyst precursor is obtained;

[0044] (2) A soluble promoter salt solution is impregnated and loaded onto the catalyst precursor prepared in step (1), and after aging, drying, calcination, and reduction, the required nickel-based bimetallic catalyst is obtained;

[0045] Among them, the soluble promoter salt is selected from soluble promoter salts containing one or more components of Ag, Au, Ru, Pt or Mo; the carrier is composed of one or more of silica, titanium dioxide, cerium dioxide or zirconium dioxide.

[0046] The present invention provides a nickel-based bimetallic catalyst prepared by the preparation method of the above nickel-based bimetallic catalyst.

[0047] The present invention also provides an application of the nickel-based bimetallic catalyst, applying the nickel-based bimetallic catalyst to the reaction of hydrogenating dimethyl oxalate to methyl glycolate; specifically including the following process: loading the nickel-based bimetallic catalyst into a fixed-bed reactor, and the catalyst is in-situ reduced with hydrogen in the device before use, the reduction temperature is 200-650 °C, and the reduction time is 2-12 h; then carry out the reaction of hydrogenating dimethyl oxalate to methyl glycolate, and the reaction conditions are: reaction temperature 170-280 °C, reaction pressure 1-3 MPa, liquid hourly space velocity of DMO is 0.1-3.0 h-1, and the molar ratio of hydrogen to dimethyl oxalate is 30:1-300:1.

[0048] All the raw materials used in the technical solution of the present invention are directly purchased.

[0049] The following uses specific examples to further elaborate on the present invention in detail.

[0050] Example 1

[0051] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0052] 1) Dissolve 3.0 g of nickel nitrate hexahydrate, 1.8 g of urea, and 0.5 g of sodium carbonate in 200 mL of deionized water to form a homogeneous solution. After diluting 65 g (25 wt.%) of silica sol with 100 mL of deionized water, mix it with the mixed solution of urea and nickel salt, raise the temperature to 70 °C and react for 48 h. After the reaction, filter by suction and wash with deionized water. Age the obtained colloid at 20 °C for 14 h, dry at 70 °C for 14 h, calcine in air at 350 °C for 10 h, and reduce in hydrogen at 300 °C for 24 h and then cool to room temperature to obtain the catalyst precursor NiTOx.

[0053] 2) Dissolve 0.003 g of silver nitrate in 10 mL of deionized water to form a homogeneous solution, impregnate it on the catalyst precursor obtained in step 1), age at 40 °C for 4 h, dry at 70 °C for 14 h, calcine at 350 °C for 8 h, and reduce at 200 °C for 12 h to obtain the nickel-based bimetallic catalyst.

[0054] The prepared nickel-based bimetallic catalyst is used for catalyzing the hydrogenation of DMO to MG. The specific process is as follows: After loading the nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, the reaction of hydrogenating DMO to MG is carried out. The reaction conditions are as follows: the reaction temperature is 220 °C, the reaction pressure is 2.0 MPa, and the liquid hourly space velocity of DMO is 0.75 h -1 , and the molar ratio of H2 to DMO is 60:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 99.1%, and the selectivity of MG is 99.3%.

[0055] Comparative Example 1

[0056] Compared with Example 1, the preparation process of the nickel-based bimetallic catalyst in this comparative example is different in that: the calcination temperature for preparing the catalyst precursor in step 1) is adjusted to 750 °C, and the calcination time is 4 h, and the rest of the operations are the same.

[0057] The prepared nickel-based bimetallic catalyst is used for catalyzing the hydrogenation of DMO to MG. The reaction conditions are the same as those in Example 1. The reaction products are analyzed by on-line chromatography. The conversion rate of DMO is 7%, and the selectivity of MG is 21%.

[0058] Comparative Example 2

[0059] Compared with Example 1, the preparation process of the nickel-based bimetallic catalyst in this comparative example is different in that: the reduction temperature for preparing the catalyst precursor in step 1) is adjusted to 850 °C, and the reduction time is 4 h, and the rest of the operations are the same.

[0060] The prepared nickel-based bimetallic catalyst is used for catalyzing the hydrogenation of DMO to MG. The reaction conditions are the same as those in Example 1. The reaction products are analyzed by on-line chromatography. The conversion rate of DMO is 1%, and the selectivity of MG is 6%.

[0061] Comparative Example 3

[0062] Compared with Example 1, the preparation process of the nickel-based bimetallic catalyst in this comparative example is different in that: in the process of preparing the catalyst precursor in step 1), before the reduction treatment, no high-temperature calcination treatment is carried out, and the rest of the operations are the same.

[0063] The prepared nickel-based bimetallic catalyst is used for catalyzing the hydrogenation of DMO to MG. The reaction conditions are the same as those in Example 1. The reaction products are analyzed by on-line chromatography. The conversion rate of DMO is 1%, and the selectivity of MG is 6%.

[0064] The catalyst precursors prepared in the above examples and each comparative example were characterized by synchrotron radiation X-ray atomic absorption spectroscopy (XAFS). The characterization results showed that the catalyst precursor prepared by the preparation method of the present invention contained obvious Ni-Si interface sites, while the catalyst precursor prepared in the comparative example did not contain Ni-Si interface sites, indicating that this preparation method can obtain a catalyst precursor with a rich interface site structure.

[0065] Example 2

[0066] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0067] 1) Dissolve 6.1 g of nickel acetate, 20 mL of ammonia water (20%), and 0.2 g of sodium bicarbonate in 200 mL of deionized water to form a homogeneous solution. Dilute 26.7 g of silica sol (25 wt.%) with 100 mL of deionized water, mix it with the mixed solution of ammonia water and nickel salt, heat up to 150 °C and react for 4 h. After the reaction, filter by suction and wash with deionized water. Age the obtained colloid at 40 °C for 4 h, dry at 120 °C for 4 h, calcine in air at 650 °C for 2 h, and reduce in hydrogen at 650 °C for 3 h, then cool to room temperature to obtain the catalyst precursor NiTOx.

[0068] 2) Dissolve 0.16 g of silver nitrate in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age at 20 °C for 14 h, dry at 120 °C for 4 h, calcine at 650 °C for 2 h, and reduce at 650 °C for 2 h to obtain the nickel-based bimetallic catalyst.

[0069] The nickel-based bimetallic catalyst prepared above was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows:

[0070] After the nickel-based bimetallic catalyst was loaded into a fixed-bed reactor for in-situ hydrogen activation, the reaction performance test for the hydrogenation of DMO to MG was carried out. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.0 h -1 , and the molar ratio of H2 to DMO was 40:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 99.3%, and the selectivity of MG was 99.5%.

[0071] Example 3

[0072] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0073] 1) Dissolve 4.5 g of nickel chloride in 100 mL of deionized water and 2.4 g of absolute ethanol to prepare solution A. Take 31.2 g of tetraethyl orthosilicate and mix it with 200 mL of deionized water to prepare solution B. Add solution A to solution B evenly under stirring conditions and react at 40 °C for 48 h. Filter and wash the precipitate. The obtained colloid is aged at 30 °C for 8 h, dried at 120 °C for 10 h, calcined in air at 450 °C for 6 h, and reduced in hydrogen at 450 °C for 6 h, and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0074] 2) Dissolve 0.047 g of silver nitrate in 5 mL of deionized water to form a uniform solution, impregnate it onto the catalyst precursor obtained in step 1), age at 30 °C for 10 h, dry at 100 °C for 10 h, calcine at 400 °C for 4 h, and reduce at 300 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0075] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows:

[0076] After loading the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, perform the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.5 h -1 , molar ratio of H2 to DMO is 50:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 99.8%, and the selectivity of MG is 99.5%. In this example, the stability of the prepared nickel-based bimetallic catalyst was evaluated. The evaluation results are as Figure 1 shown. When the reaction system runs for ≥780 h, it still shows excellent DMO conversion rate and MG selectivity, indicating that the catalyst prepared in this example has high stability.

[0077] Example 4

[0078] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0079] 1) Dissolve 7.4 g of nickel nitrate hexahydrate, 0.2 g of sodium hydroxide, and 4.6 g of urea in 100 mL of deionized water to form a uniform solution. After preparing a suspension of 5 g of fumed silica and 3.5 g of titanium dioxide powder in 200 mL of deionized water, mix it with the mixed solution of urea and nickel salt and heat it to 90 °C for reaction for 24 h. After the reaction, perform suction filtration and wash three times with deionized water. The obtained colloid is aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 500 °C for 4 h, and reduced in hydrogen at 450 °C for 5 h, and then cooled to room temperature to obtain the catalyst NiTOx.

[0080] 2) Dissolve 0.13 g of silver nitrate in deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age it at 35 °C for 8 h, dry it at 90 °C for 12 h, calcine it at 450 °C for 6 h, and reduce it at 350 °C for 4 h to obtain a nickel-based bimetallic catalyst.

[0081] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows: After loading the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, perform the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 0.75 h -1 , and the molar ratio of H2 to DMO is 50:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 99.8%, and the selectivity of MG is 98.4%.

[0082] Example 5

[0083] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0084] 1) Dissolve 7.4 g of nickel nitrate hexahydrate, 0.2 g of ammonium carbonate, and 4.6 g of urea in 100 mL of deionized water to form a homogeneous solution. After preparing a suspension of 6 g of fumed silica and 2.5 g of zirconia powder in 200 mL of deionized water, mix it with the mixed solution of urea and nickel salt, heat it to 100 °C and react for 18 h. After the reaction, perform suction filtration and wash three times with deionized water. The obtained colloid is aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 500 °C for 4 h, and reduced in hydrogen at 450 °C for 6 h and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0085] 2) Dissolve 0.213 g of chloroplatinic acid hexahydrate solution in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age it at 30 °C for 10 h, dry it at 110 °C for 12 h, calcine it at 400 °C for 6 h, and reduce it at 500 °C for 3 h to obtain a nickel-based bimetallic catalyst.

[0086] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows:

[0087] After loading the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, perform the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.0 h -1, the molar ratio of H2 to DMO was 40:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 99.6%, and the selectivity of MG was 95.8%.

[0088] Example 6

[0089] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0090] 1) Dissolve 7.4 g of nickel nitrate hexahydrate and 4.6 g of urea in 100 mL of deionized water to form a homogeneous solution. After preparing a suspension of 7 g of fumed silica and 1.5 g of zirconia powder in 200 mL of deionized water, mix it with the mixed solution of urea and nickel salt, heat it to 90 °C and react for 24 h. After the reaction, filter and wash the precipitate. The obtained colloid is aged at 30 °C for 8 h, dried at 110 °C for 10 h, calcined in air at 450 °C for 5 h, reduced in hydrogen at 550 °C for 6 h, and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0091] 2) Dissolve 0.17 g of ruthenium trichloride in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the nickel precursor obtained in step 1), age it at 30 °C for 10 h, dry it at 120 °C for 10 h, calcine it at 450 °C for 6 h, and reduce it at 500 °C for 2 h to obtain the nickel-based bimetallic catalyst.

[0092] The nickel-based bimetallic catalyst prepared above was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows:

[0093] After loading the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, the reaction performance test of DMO hydrogenation to MG was carried out. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, and the liquid hourly space velocity of DMO was 1.0 h -1 , the molar ratio of H2 to DMO was 40:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 99.6%, and the selectivity of MG was 94.3%.

[0094] Example 7

[0095] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0096] 1) Dissolve 5.0 g of nickel nitrate hexahydrate and 3.1 g of urea in 100 mL of deionized water to form a homogeneous solution. After preparing a suspension of 6 g of fumed silica and 3 g of zirconia powder in 200 mL of deionized water, mix it with the mixed solution of urea and nickel salt, heat up to 90 °C and react for 24 h. After the reaction, perform suction filtration and wash three times with deionized water. The obtained colloid is aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 400 °C for 4 h, and reduced in hydrogen at 600 °C for 3 h, and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0097] 2) Dissolve 0.124 g of chloroauric acid in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the nickel precursor obtained in step 1), age at 25 °C for 12 h, dry at 70 °C for 12 h, calcine at 450 °C for 4 h, and reduce at 350 °C for 3 h to obtain the nickel-based bimetallic catalyst.

[0098] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows: After loading the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, perform the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.0 h -1 , and the molar ratio of H2 to DMO is 40:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 99.4%, and the selectivity of MG is 99.8%.

[0099] Example 8

[0100] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0101] 1) Dissolve 5.0 g of nickel nitrate hexahydrate and 3.1 g of urea in 100 mL of deionized water to form a homogeneous solution. After preparing a suspension of 6 g of fumed silica and 3 g of zirconia powder in 200 mL of deionized water, mix it with the mixed solution of urea and nickel salt, heat up to 60 °C and react for 36 h. After the reaction, perform suction filtration and wash three times with deionized water. The obtained colloid is aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 500 °C for 4 h, and reduced in hydrogen at 500 °C for 3 h, and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0102] 2) Dissolve 0.06 g of ammonium molybdate in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age at 30 °C for 12 h, dry at 70 °C for 12 h, calcine at 450 °C for 4 h, and reduce at 650 °C for 3 h to obtain the nickel-based bimetallic catalyst.

[0103] The prepared nickel-based bimetallic catalyst was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows: The nickel-based bimetallic catalyst was loaded into a fixed-bed reactor and in-situ hydrogen activation was carried out, followed by the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.0 h -1 , and the molar ratio of H2 to DMO was 80:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 91.6%, and the selectivity of MG was 92.8%.

[0104] Example 9

[0105] The preparation method of the nickel-based bimetallic catalyst in this example included the following steps:

[0106] 1) 7.4 g of nickel nitrate hexahydrate and 4.6 g of urea were dissolved in 100 mL of deionized water to form a homogeneous solution. 5.5 g of fumed silica and 3.0 g of cerium dioxide powder were made into a suspension with 200 mL of deionized water, and then mixed with the mixed solution of urea and nickel salt. The temperature was raised to 80 °C and the reaction was carried out for 24 h. After the reaction, filtration was carried out, and it was washed three times with deionized water. The obtained colloid was aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 400 °C for 4 h, reduced in hydrogen at 550 °C for 3 h, and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0107] 2) 0.13 g of ammonium molybdate was dissolved in 5 mL of deionized water to form a homogeneous solution, impregnated onto the catalyst precursor obtained in step 1), aged at 25 °C for 12 h, dried at 70 °C for 12 h, calcined at 450 °C for 4 h, and reduced at 500 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0108] The prepared nickel-based bimetallic catalyst was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows: The nickel-based bimetallic catalyst was filled into a fixed-bed reactor and in-situ hydrogen activation was carried out, followed by the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 1.0 h -1 , and the molar ratio of H2 to DMO was 80:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 92.6%, and the selectivity of MG was 92.1%.

[0109] Example 10

[0110] The preparation method of the nickel-based bimetallic catalyst in this example included the following steps:

[0111] 1) Dissolve 7.4 g of nickel nitrate hexahydrate, 10 mL of ammonia water, and 2.0 g of solid sodium bicarbonate in 150 mL of deionized water to form a homogeneous solution. After diluting 4.0 g of fumed silica and 4.5 g of titanium dioxide powder with 150 mL of deionized water, mix them with the mixed solution of ammonia water, nickel salt, and sodium bicarbonate, heat up to 100 °C and react for 24 h. After the reaction, perform suction filtration and wash three times with deionized water. The obtained colloid is aged at 40 °C for 6 h, dried at 80 °C for 8 h, calcined in air at 500 °C for 4 h, and reduced in hydrogen at 550 °C for 5 h and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0112] 2) Dissolve 0.08 g of silver nitrate in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age at 25 °C for 12 h, dry at 70 °C for 12 h, calcine at 450 °C for 4 h, and reduce at 400 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0113] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows: After filling the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, perform the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 0.1 h -1 , and the molar ratio of H2 to DMO is 300:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 100%, and the selectivity of MG is 78.3%.

[0114] Example 11

[0115] The preparation method of the nickel-based bimetallic catalyst in this example includes the following steps:

[0116] 1) Dissolve 5.0 g of nickel nitrate hexahydrate in 100 mL of deionized water and 2.4 g of absolute ethanol to form solution A; mix 31.2 g of tetraethyl orthosilicate, 1.8 g of tetrabutyl titanate with 200 mL of deionized water to prepare solution B. Add solution A to solution B uniformly under stirring conditions and react at 120 °C for 4 h. Filter and wash the precipitate. The obtained colloid is dried at 120 °C for 10 h, calcined in air at 500 °C for 6 h, and reduced in hydrogen at 450 °C for 6 h and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0117] 2) Dissolve 0.095 g of silver nitrate in 5 mL of deionized water to form a homogeneous solution, impregnate it onto the catalyst precursor obtained in step 1), age at 25 °C for 12 h, dry at 70 °C for 12 h, calcine at 450 °C for 4 h, and reduce at 300 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0118] The prepared nickel-based bimetallic catalyst above was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows: After the nickel-based bimetallic catalyst above was filled into a fixed-bed reactor and in-situ hydrogen activation was carried out, the reaction performance test for the hydrogenation of DMO to MG was carried out. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 3.0 h -1 , and the molar ratio of H2 to DMO was 30:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 79.4%, and the selectivity of MG was 99.1%.

[0119] Example 12

[0120] The preparation method of the nickel-based bimetallic catalyst in this example included the following steps:

[0121] 1) 5.0 g of nickel nitrate hexahydrate was dissolved in 100 mL of deionized water and 2.4 g of absolute ethanol to form solution A; 15.0 g of sodium silicate was mixed with 200 mL of deionized water to prepare solution B. Solution A was added to solution B uniformly under stirring conditions and reacted at 120 °C for 4 h. The precipitate was filtered and washed. The obtained colloid was dried at 120 °C for 10 h, calcined in air at 500 °C for 6 h, and reduced in hydrogen at 450 °C for 6 h and then cooled to room temperature to obtain the catalyst precursor NiTOx.

[0122] 2) 0.095 g of silver nitrate was dissolved in 5 mL of deionized water to form a uniform solution, impregnated onto the catalyst precursor obtained in step 1), aged at 25 °C for 12 h, dried at 70 °C for 12 h, calcined at 450 °C for 4 h, and reduced at 300 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0123] The prepared nickel-based bimetallic catalyst above was used for the catalytic hydrogenation of DMO to MG. The specific process was as follows: After the nickel-based bimetallic catalyst above was filled into a fixed-bed reactor and in-situ hydrogen activation was carried out, the reaction performance test for the hydrogenation of DMO to MG was carried out. The reaction conditions were: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 3.0 h -1 , and the molar ratio of H2 to DMO was 30:1. The reaction products were analyzed by on-line gas chromatography. The conversion rate of DMO was 82.4%, and the selectivity of MG was 98.9%.

[0124] Example 13

[0125] The preparation method of the nickel-based bimetallic catalyst in this example included the following steps:

[0126] 1) Dissolve 5.0 g of nickel nitrate hexahydrate in 100 mL of deionized water and 2.4 g of absolute ethanol to prepare solution A; take 15.0 g of sodium silicate, 1.0 g of cerium nitrate, 1.8 g of zirconium nitrate and mix them with 200 mL of deionized water to prepare solution B. Add solution A to solution B evenly under stirring conditions, react at 120 °C for 4 h, filter and wash the precipitate, dry the obtained colloid at 120 °C for 10 h, calcine in air at 500 °C for 6 h, and reduce in hydrogen at 450 °C for 6 h, then cool to room temperature to obtain the catalyst precursor NiTOx.

[0127] 2) Dissolve 0.095 g of silver nitrate in 5 mL of deionized water to prepare a uniform solution, impregnate it on the catalyst precursor obtained in step 1), age at 25 °C for 12 h, dry at 70 °C for 12 h, calcine at 450 °C for 4 h, and reduce at 300 °C for 4 h to obtain the nickel-based bimetallic catalyst.

[0128] Use the above-prepared nickel-based bimetallic catalyst for the catalytic hydrogenation of DMO to MG. The specific process is as follows: Fill the above nickel-based bimetallic catalyst into a fixed-bed reactor for in-situ hydrogen activation, and then conduct the reaction performance test for the hydrogenation of DMO to MG. The reaction conditions are: reaction temperature 220 °C, reaction pressure 2.0 MPa, liquid hourly space velocity of DMO 3.0 h -1 [[-1]], and the molar ratio of H2 to DMO is 30:1. The reaction products are analyzed by on-line gas chromatography. The conversion rate of DMO is 77.3%, and the selectivity of MG is 99.2%.

[0129] The compositions of the nickel-based bimetallic catalysts prepared in the above examples and comparative examples, as well as the process parameters and activity evaluation results of the catalysts used for the catalytic hydrogenation of DMO to MG, are recorded in Table 1.

[0130] Table 1 Activity evaluation of catalysts in each example

[0131]

[0132]

[0133] As shown in the data of Table 1, when the catalyst prepared by the preparation method of the nickel-based bimetallic catalyst provided by the present invention is used for the catalytic hydrogenation of DMO to MG, it shows extremely excellent catalytic activity and MG selectivity. And the nickel-based bimetallic catalyst prepared by the method of the present invention can still achieve excellent catalytic activity and MG selectivity when the loading amount of the promoter metal is low. This provides a new preparation route for the production process of hydrogenating DMO to MG, which has a lower production cost, a safer process and excellent catalytic activity.

[0134] The above embodiments are merely illustrative of the present invention and do not limit the present invention. After reading this specification, those skilled in the art may make modifications to these embodiments that do not contribute creatively, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A preparation method of a nickel-based bimetallic catalyst for the hydrogenation reaction of dimethyl oxalate to methyl glycolate, characterized in that, It includes the following steps: (1) Dissolve the soluble nickel salt in water, load it onto a carrier, and obtain a catalyst precursor after drying, calcination, and reduction treatments; (2) Impregnate and load the soluble promoter salt solution onto the catalyst precursor prepared in step (1), and obtain the required nickel-based bimetallic catalyst after aging, drying, calcination, and reduction; Among them, the soluble promoter salt is selected from soluble promoter salts containing one or several components of Ag, Au, Ru, Pt, or Mo; The carrier is composed of one or several of silica, titanium dioxide, cerium dioxide, or zirconium dioxide; Among them, in step (1), the soluble nickel salt is dissolved in water and loaded onto the carrier by the sol-gel method. The preparation of the catalyst precursor includes the following steps: (i) Dissolve the soluble nickel salt in deionized water and a certain proportion of absolute ethanol to prepare solution A; (ii) Take an appropriate amount of the carrier precursor and mix it with deionized water to prepare solution B; (iii) Add solution A to solution B, react at 40-120°C for 4-48 h, age, dry, and calcine, and then reduce it in hydrogen at 300-650°C for 3-24 h to obtain the catalyst precursor; the carrier precursor is selected from one or several of tetraethyl orthosilicate, sodium silicate, tetrabutyl titanate, cerium nitrate, or zirconium nitrate; or, In step (1), the soluble nickel salt is dissolved in water and loaded onto the carrier by the precipitation method. The preparation of the catalyst precursor includes the following steps: (i) Dissolve the soluble nickel salt and the precipitating agent in deionized water to prepare a homogeneous solution; (ii) Mix the carrier precursor with an appropriate amount of water, and then mix it with the homogeneous solution prepared in step (i), react at 70-150°C for 4-48 h, filter and wash the precipitate; (iii) Age, dry, and calcine the obtained colloid, and then reduce it in hydrogen at 300-650°C for 3-24 h to obtain the catalyst precursor; the precipitating agent is selected from one or several of ammonia water, urea, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, sodium carbonate, or sodium bicarbonate; In the prepared nickel-based bimetallic catalyst, the content of nickel is 3.0-20.0 wt.%, the content of the promoter metal is 0.01-1.0 wt.%, and the rest is the carrier.

2. The preparation method according to claim 1, characterized in that, In the preparation steps of the catalyst precursor obtained by dissolving the soluble nickel salt in water and loading it onto the carrier by the sol-gel method, in step (i), the molar ratio of the soluble nickel salt to absolute ethanol is 1:1-3.

5.

3. The preparation method according to claim 1, characterized in that, In step (1), after loading the soluble nickel salt onto the carrier, age it at 20-40°C for 4-14 h, dry it at 70-120°C for 4-14 h, calcine it in air at 350-650°C for 2-10 h, and then perform reduction treatment to obtain the catalyst precursor.

4. The preparation method according to claim 1, wherein The soluble nickel salt is selected from one or several of nickel nitrate, nickel acetate, and nickel chloride.

5. The preparation method according to claim 1, wherein In step (2), the soluble auxiliary agent salt solution is impregnated and loaded onto the catalyst precursor obtained in step (1), and then aged at 20-40°C for 4-14 hours, dried at 70-120°C for 4-14 hours, calcined at 350-650°C for 2-8 hours, and reduced at 200-650°C for 2-12 hours to obtain a nickel-based bimetallic catalyst.

6. A nickel-based bimetallic catalyst prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of a nickel-based bimetallic catalyst as described in claim 6, characterized in that, Used in the reaction of hydrogenating dimethyl oxalate to produce methyl glycolate.

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