Catalyst for co-production of methanol and ethylene glycol from ethylene carbonate based on additive manufacturing, and preparation method and application thereof

Abstract

The invention relates to a catalyst for preparing methanol and co-producing ethylene glycol from ethylene carbonate based on additive manufacturing, a preparation method and application, the catalyst comprises 10-70 wt.% of Cu, 0.5-11 wt.% of boron oxide as an auxiliary agent and the balance of the carrier, and the Cu accounts for 10-70 wt.% of the total amount of the catalyst, and the boron oxide as the auxiliary agent accounts for 0.5-11 wt.% of the total amount of the catalyst. According to the invention, non-noble metal Cu is used as a catalyst active component, non-metal oxide boron oxide is used as an auxiliary agent, silicon dioxide is used as a carrier, and based on an additive manufacturing selective sintering technology, the interaction among the three components is optimal. Therefore, the conversion rate of ethylene carbonate and the selectivity of the product can be improved under relatively mild conditions, and meanwhile, excellent stability is shown in a hydrogenation reaction. The preparation raw materials are easy to obtain, the cost is low, the process is simple and controllable, the structure is stable, the operability is high, and the industrial application prospect is good.

Description

Technical Field

[0001] The present invention designs a preparation method of a catalyst for producing methanol and co-producing ethylene glycol from ethylene carbonate based on additive manufacturing, belonging to the technical field of catalytic hydrogenation under mild conditions. Specifically, it is a preparation method and application of a supported Cu-based catalyst modified with B 2 O 3 as an auxiliary agent. Background Art

[0002] Carbon dioxide (CO 2 ) is a greenhouse gas, and the increase in its concentration is one of the main driving forces of global warming, posing a threat to the ecological balance and human survival. However, CO 2 is also a cheap and easily available carbon resource. Its rational utilization can not only alleviate the greenhouse effect, but also solve the problem of resource shortage and has great economic value. Converting CO 2 into methanol (MeOH) and ethylene glycol (EG), as an important way of resource utilization, shows significant potential.

[0003] Methanol (MeOH) is an important basic chemical in the global chemical industry, with a huge demand. It occupies an important position in the chemical field and is commonly used as a solvent, intermediate, fuel additive, etc. The global annual demand is estimated to exceed 80 million tons. Currently, the main sources of methanol include steam reforming and partial oxidation of natural gas, coal or heavy oil, and gasifying biomass (such as straw, wood chips, municipal solid waste, etc.) to produce syngas (the main components are CO and H 2 ), and then converting the syngas into methanol. The methods of steam reforming and partial oxidation of natural gas, coal or heavy oil rely on fossil fuels and will produce a large amount of CO 2 emissions, exacerbating the greenhouse effect. The method of using biomass requires relatively harsh reaction conditions and high pretreatment costs. Biomass gasification requires a high temperature (about 700 - 900 °C), while the methanol synthesis stage requires a temperature (about 200 - 300 °C) and pressure (about 5 - 10 Mpa).

[0004] Ethylene glycol (EG) is another chemical product with extremely high demand. The global annual consumption of ethylene glycol is estimated to exceed 30 million tons. It is mainly used to produce unsaturated polyesters and is also a raw material for the production of surfactants, plasticizers, emulsifiers, demulsifiers, etc. In addition, it is widely used as a humectant, antifreeze, lubricant, mildew-proof agent, and solvent in industries such as medicine, building insulation materials, food, and cosmetics. Ethylene glycol is mainly prepared through the hydration reaction of the petroleum derivative ethylene oxide. Ethylene oxide is usually produced by the oxidation of ethylene. Its production process highly depends on petroleum and also faces problems of limited resources and environmental pollution. In addition, harmful substances such as acetaldehyde are released during the production process of ethylene oxide, posing a threat to the health of production personnel and environmental safety. The preparation and production of both of them need to develop new clean, efficient, and mild paths.

[0005] Traditional paths for preparing methanol require high-temperature and high-pressure reaction conditions or rely on fossil raw materials. Traditional methods for preparing ethylene glycol are prone to releasing toxic substances and rely on petroleum. Ethylene oxide (EO) and carbon dioxide (CO 2 ) to prepare ethylene carbonate have formed a mature industrial system. Using carbon dioxide as the raw material and ethylene carbonate as the intermediate, catalytic hydrogenation of ethylene carbonate to prepare methanol and ethylene glycol can design a new set of highly efficient and environmentally friendly paths for the conversion and utilization of carbon dioxide. Copper-based catalysts are widely used in the ester hydrogenation system due to their good C-O / C=O bond selective hydrogenation ability. However, copper-based supported catalysts prepared by the traditional impregnation method (IM) have low methanol selectivity and poor stability during the catalytic process. On the other hand, in the high-temperature and high-pressure hydrogenation system, copper-based catalysts generally have problems such as easy sintering and aggregation of copper and easy deactivation of the catalyst after long-term use. In addition, there are problems of high energy consumption and safe production under the harsh reaction conditions of high temperature and high pressure. Therefore, for the green and new high-economy path with an atomic utilization rate of 100% for catalytic hydrogenation of ethylene carbonate to prepare methanol and ethylene glycol using carbon dioxide as the raw material and ethylene carbonate as the intermediate, developing a catalyst with high activity, high stability, and high selectivity for the catalytic hydrogenation of ethylene carbonate under relatively mild reaction conditions is the key to the successful realization of this path and the efficient conversion and utilization of carbon dioxide.

[0006] Additive manufacturing technology (AM), also known as 3D printing, is a new manufacturing technology that uses a computer to build a digital model and stacks special new materials layer by layer to manufacture physical objects. It stands in sharp contrast to traditional subtractive manufacturing (such as turning, milling, and drilling). This technology can manufacture complex geometric shapes that are difficult to achieve by traditional methods, such as porous structures, internal channels, and lightweight structures. Additive manufacturing technology has been applied in multiple industries such as biomedicine, aerospace, architecture, and art design, bringing relatively high technological progress to existing technologies. With its digital design and intelligent production process, additive manufacturing technology is driving the innovation of modern manufacturing. Its green manufacturing characteristics contribute to the vision of sustainable development. This technology subverts the limitations of traditional manufacturing, realizes the precise forming of complex shaped components from micro to macro, significantly improves production efficiency and product performance. Relying on three-dimensional modeling and materials science, additive manufacturing simplifies the manufacturing process, accelerates the iteration from idea to physical object, and stimulates innovative design and functional breakthroughs. At the same time, the local production strategy strengthens the resilience of the supply chain and improves the response speed, laying a foundation for the agile transformation and green future of the manufacturing industry. The industrial practicability of Cu-based supported catalysts is defined by their stability, reusability, and catalytic activity. Additive manufacturing technology enables precise structural regulation. The macroscopic structure improves the microscale material recycling efficiency and recycling potential, which is crucial for innovating the Cu-based supported catalyst system and enhancing its industrial competitiveness. Summary of the Invention

[0007] The present invention aims to overcome the deficiencies of the prior art. Aiming at the problems in the existing technology of catalytic hydrogenation of ethylene carbonate to methanol and ethylene glycol, such as easy sintering and aggregation of catalyst Cu particles, unstable catalyst, low reusability, and low methanol selectivity, a preparation method of a supported Cu-based catalyst modified with B based on additive manufacturing is proposed to solve the problems in the above background technology. 2 0 3 The above problems in the background technology are solved.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A catalyst for the production of methanol and ethylene glycol by the reaction of ethylene carbonate based on additive manufacturing. The catalyst is characterized in that: the additive manufacturing powder of the catalyst is prepared by the precipitation gel method, and a catalyst with a highly selective geometry is manufactured by selective laser sintering technology (SLS). The structural general formula of the catalyst is Cu-M / X-PG, where M is the promoter boron oxide, X is the carrier silica, and PG is the preparation method of the precipitation gel method. The mass percentage content of metallic Cu in the catalyst is 5-75%, the mass percentage content of the promoter M is 0.1-16%, and the rest is the carrier. A preferred scheme is: the percentage content of metallic Cu is preferably 10-70%, more preferably 50-70%, the percentage content of boron oxide as the promoter is preferably 0.5-11%, and the rest is the carrier.

[0010] Further: the metal Cu particle size in the catalyst additive manufacturing powder is 8 - 10 nm, the surface area of metal Cu in the catalyst additive manufacturing powder is 65.5 - 79.8 m 2 / g, the specific surface area of the catalyst is 168 - 223 m 2 / g, the dispersion degree of Cu in the catalyst is 11.1 - 13.4%, the surface area of zero-valent copper Cu 0 in the catalyst is 72.1 - 86.9 m2 / g, and the average size of Cu particles in the catalyst is 7.5 - 9.0 nm.

[0011] The present invention also provides a preparation method of a catalyst for producing ethylene glycol and co-producing methanol from ethylene carbonate based on additive manufacturing, which specifically includes the following steps:

[0012] (1) Stir and mix a copper precursor salt with pure water to obtain a copper precursor salt solution;

[0013] (2) Drop an alkaline agent into the copper precursor salt solution obtained in (1) at a constant speed and stir vigorously until the pH value is greater than 10 to form a copper precursor salt suspension;

[0014] (3) Add a silicon source to the copper precursor salt suspension obtained in step (2) to disperse and stabilize the precipitate colloids in the copper precursor salt suspension to form a gel-like mixture;

[0015] (4) Age, filter the gel-like mixture obtained in step (3), wash it thoroughly with hot water, dry it thoroughly, and then calcine it in an air atmosphere to obtain a catalyst precursor;

[0016] (5) Immerse the catalyst precursor obtained in step (4) after pre-calcination in an aqueous solution of boric acid (H 3 BO 3 ), and then grind and screen it to obtain a catalyst powder;

[0017] (6) Put the catalyst powder obtained in step (5) into the powder cylinder of a selective sintering 3D printer, and uniformly spread the catalyst powder on the printing build platform for preheating;

[0018] (7) Selectively sinter and cool the catalyst powder in step (6) according to a three-dimensional model established by modeling software;

[0019] (8) Take out the finished catalyst product in step (7), and carry out powder removal, surface cleaning, grinding treatment and quality inspection.

[0020] Further, the copper precursor salt in step (1) is any one of copper acetate, copper nitrate, copper chloride, and copper sulfate.

[0021] Further, the alkaline agent in step (2) is any one of ammonia water, ammonium carbonate or sodium hydroxide.

[0022] Further, the silicon source in step (3) is any one of sodium silicate and silica sol.

[0023] Further, the preferred temperature for the aging in step (4) is 100 °C, the aging time is 3 h, the preferred temperature for calcination is 550 °C, and the calcination time is 3 hours.

[0024] Further, the geometric structure of the additive manufacturing in step (7) is a porous structure.

[0025] The present invention also provides an application of the catalyst for producing methanol and co-producing ethylene glycol by catalytic hydrogenation of ethylene carbonate based on additive manufacturing. The reaction liquid concentration of ethylene carbonate is 10-100%, tetrahydrofuran (THF) is used as the solvent for the catalytic hydrogenation reaction liquid of ethylene carbonate, and the reaction conditions are as follows: the reaction temperature is 140-200 °C, the hydrogen pressure is 2-4 MPa, the reaction time is 4-8 h, the catalyst dosage is 3-3.5 g, preferably 3.2 g.

[0026] The catalyst of the present invention needs to be activated before use: it is reduced in a hydrogen atmosphere with a flow rate of 20-60 ml / min at 277-447 °C for 3-5 h to obtain an active catalyst.

[0027] Advantages of the present invention:

[0028] 1. The present invention uses non-precious metal Cu as the active component of the catalyst, non-metal oxide boron oxide as the promoter, and silica as the carrier, and makes the three interact optimally based on the selective sintering technology of additive manufacturing. The preparation raw materials are easy to obtain, the cost is low, the process is simple and controllable, the structure is stable, the operability is strong, and it has good industrial application prospects.

[0029] 2. The supported Cu-based catalyst prepared by the precipitation gel method of the present invention shows excellent selectivity and stability under the reaction conditions of catalytic hydrogenation of ethylene carbonate to prepare methanol and ethylene glycol under relatively mild conditions (the conversion rate of ethylene carbonate is as high as 100%, the selectivity of methanol is as high as 99%, and the selectivity of ethylene glycol is as high as 96-99%). The catalyst can be recycled many times after filtration and separation. Description of the drawings

[0030] Figure 1 is a process flow chart of the preparation of the catalyst for producing methanol and co-producing ethylene glycol by catalytic hydrogenation of ethylene carbonate based on additive manufacturing of the present invention.

[0031] Figure 2 is a diagram showing the relationship between the reaction TOF and the product yield under different surface structures (average particle size of Cu particles, Cu 0 surface area) in Examples 8 to 15 of the present invention.

[0032] Figure 3 It is a comparison graph of the change in the diameter of Cu particles under TEM observation after multiple cycles of use of Example 11 and Example 16 of the present invention.

[0033] Figure 4 It is a graph of the stability evaluation results of the catalyst prepared in Example 25 of the present invention during the long-term use in the catalytic hydrogenation of ethylene carbonate to prepare methanol and ethylene glycol.

[0034] Figure 5 It is an introduction to the porous structure model and basic reaction principle of the supported catalyst of the present invention. The reactants are ethylene carbonate and hydrogen. The reactants pass through the pores of the catalyst and react with the surface active component-loaded Cu to obtain methanol and ethylene glycol. Detailed implementation manners

[0035] The present invention will be further described in detail below in conjunction with the drawings and examples. The purpose is to deepen the understanding rather than limit the protection scope. Parameters such as mass, reaction conditions, process parameters, etc. are only examples. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention. The experimental methods without specific conditions in the examples are usually carried out according to the conventional conditions and the conditions described in the manuals. The general equipment, materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0036] Example 1

[0037] Weigh 10.56 g of copper nitrate trihydrate and dissolve it in 125 ml of distilled water in a beaker to obtain a copper nitrate solution. Immerse the SiO 2 support in an aqueous solution containing a calculated amount of copper nitrate at room temperature, and carry out impregnation on a magnetic stirrer for 2 - 3 h. Place the impregnated catalyst sample in an oven and dry it at 120 °C for 12 hours, then calcine it in a muffle furnace at 500 °C in a nitrogen stream for 3 h, and grind and sieve it (60 - 180 mesh). Reduce and activate the sieved calcined sample in a hydrogen atmosphere at 400 °C for 3 h to obtain the active catalyst 1 provided by the present invention.

[0038] Example 2

[0039] The operation is the same as that in Example 1, except that 31.65 g of copper nitrate trihydrate is used instead of 10.56 g of copper nitrate trihydrate, to obtain the active catalyst 2 provided by the present invention.

[0040] Example 3

[0041] The operation is the same as that in Example 1, except that 52.75 g of copper nitrate trihydrate is used instead of 10.56 g of copper nitrate trihydrate, to obtain the active catalyst 3 provided by the present invention.

[0042] Example 4

[0043] The operation was the same as that in Example 1, except that 73.86 g of copper nitrate trihydrate was used instead of 10.56 g of copper nitrate trihydrate, to obtain the active catalyst 4 provided by the present invention.

[0044] Example 5

[0045] Weigh 20.00 g of copper nitrate trihydrate and dissolve it in 125 ml of distilled water in a beaker with stirring to obtain a copper nitrate solution. Slowly add 15 wt% NaOH solution dropwise with stirring until pH > 10. After obtaining a suspension, add 29.20 g of 30% silica sol by mass to disperse and stabilize the precipitate particles. Heat up to 80 °C and cure for 3 h. Dry at 120 °C for 12 h, calcine in a muffle furnace at 500 °C in a nitrogen stream for 3 h, grind and sieve to obtain a powder (60 - 80 mesh). Reduce and activate the obtained powder in a hydrogen atmosphere at 400 °C for 3 h, to obtain the active catalyst 5 provided by the present invention.

[0046] Example 6

[0047] Weigh 20.00 g of copper nitrate trihydrate and dissolve it in 125 ml of distilled water in a beaker with stirring to obtain a copper nitrate solution. Slowly add 15 wt% NaOH solution dropwise with stirring until pH > 10. After obtaining a suspension, add 28.40 g of 20% silica sol by mass to disperse and stabilize the precipitate particles. Heat up to 80 °C and cure for 3 h. Dry at 120 °C for 12 h, calcine in a muffle furnace at 500 °C in a nitrogen stream for 3 h, grind and sieve to obtain a powder (60 - 80 mesh). Reduce and activate the sieved powder in a hydrogen atmosphere at 400 °C for 3 h, to obtain the active catalyst 6 provided by the present invention.

[0048] Example 7

[0049] Weigh 15.00 g of copper nitrate trihydrate and dissolve it in 125 ml of distilled water in a beaker with stirring to obtain a copper nitrate solution. Slowly add 15 wt% NaOH solution dropwise with stirring until pH > 10. After obtaining a suspension, add 16.80 g of 25% silica sol by mass to disperse and stabilize the precipitate particles. Heat up to 80 °C and cure for 3 h. Dry at 120 °C for 12 h, calcine in a muffle furnace at 500 °C in a nitrogen stream for 3 h, grind and sieve (60 - 80 mesh). Reduce and activate the sieved calcined sample in a hydrogen atmosphere at 400 °C for 3 h, to obtain the active catalyst 7 provided by the present invention.

[0050] Example 8

[0051] Weigh 15.00 g of copper nitrate trihydrate and dissolve it by stirring in 125 ml of distilled water in a beaker to obtain a copper nitrate solution. Slowly add 15 wt% NaOH solution dropwise while stirring until the pH > 10. After obtaining a suspension, add 12.40 g of 20% silica sol by mass to disperse and stabilize the precipitate particles, and then heat to 80 °C for 3 h of aging. Dry at 120 °C for 12 h, and calcine in a muffle furnace at 500 °C for 3 h in a nitrogen stream, then grind and sieve (60 - 80 mesh). Reduce and activate the sieved calcined sample in a hydrogen atmosphere at 400 °C for 3 h to obtain the active catalyst 8 provided by the present invention.

[0052] In-situ reduction of the catalyst and evaluation of catalytic performance:

[0053] In the present invention, the hydrogenation reaction of ethylene carbonate is carried out in a vertical fixed-bed reactor.

[0054] Load 3.2 g of catalyst powder with a particle size of (60 - 80) mesh (i.e., active catalysts 1 - 8, hereinafter referred to as catalysts 1 - 8) into a stainless-steel tubular reactor, insert a thermocouple into the catalyst bed to ensure uniform heating, add a tetrahydrofuran solution of 25% ethylene carbonate by mass and hydrogen in a molar ratio of 30:1, and pressurize to 3 MPa. React at 160 °C, and set the weight hourly space velocity (WHSV) of ethylene carbonate to 0.2 h -1 , During the reaction, maintain the reaction pressure by supplementing H 2 , The reaction time is 6 h, and after the reaction, cool in an ice bath. Qualitative and quantitative analysis of the experimental products is carried out by gas chromatography-mass spectrometry.

[0055] Table 1: Performance evaluation of catalyst powders prepared by different methods

[0056]

[0057] It can be seen from Table 1 that by comparing Examples 1 - 4 with 5 - 8, it can be seen that the catalyst powder prepared by the precipitation gel method (PG) has a higher conversion rate (up to 99%) and product selectivity (93% for methanol and 95% for ethylene glycol) compared to the impregnation method (IM). The catalyst prepared by the precipitation gel method has better dispersion and stability. When the Cu loading is 50 - 70%, the catalyst shows better catalytic activity.

[0058] Example 9

[0059] The operation is the same as in Example 8, except that the calcination temperature in the muffle furnace is 350 °C instead of 500 °C in the muffle furnace, to obtain the active catalyst 9 provided by the present invention.

[0060] Example 10

[0061] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 450 °C instead of 500 °C in the muffle furnace, and the active catalyst 10 provided by the present invention is obtained.

[0062] Example 11

[0063] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 550 °C instead of 500 °C in the muffle furnace, and the active catalyst 11 provided by the present invention is obtained.

[0064] Example 12

[0065] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 600 °C instead of 500 °C in the muffle furnace, and the active catalyst 12 provided by the present invention is obtained.

[0066] Example 13

[0067] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 650 °C instead of 500 °C in the muffle furnace, and the active catalyst 13 provided by the present invention is obtained.

[0068] Example 14

[0069] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 750 °C instead of 500 °C in the muffle furnace, and the active catalyst 14 provided by the present invention is obtained.

[0070] Example 15

[0071] The operation is the same as that in Example 8, except that the calcination temperature in the muffle furnace is 850 °C instead of 500 °C in the muffle furnace, and the active catalyst 15 provided by the present invention is obtained.

[0072] The catalyst evaluation method is the same as above, and the performance evaluation results of the catalyst are shown in Table 2.

[0073] Table 2: Performance evaluation of catalyst powders prepared at different calcination temperatures

[0074]

[0075] Determine the average particle size of different Cu particles and the yields of various products participating in the reaction of the present invention under the Cu 0 surface area. The test conditions are the same as those for catalyst evaluation. Using N 2 O decomposition adsorption method to determine the average particle size of Cu particles and the Cu 0 surface area. Under UHV conditions, using argon as the protective gas, gradually introduce N 2 O gas into the reaction chamber, control its partial pressure, monitor the adsorption of N 2 O, and the consumption of N 2 O can be tracked by a mass spectrometer, and observe N 2The adsorption behavior of O on the copper surface was recorded, and the change in the adsorption amount over time was monitored. By using the coverage data and combining with TEM images, the number of active sites on the copper surface was estimated, and the average particle size of Cu particles and the surface area of Cu were calculated. The test results are as follows 0 shown in Figure 2 . It can be seen from Figure 2 that when the surface area of the zero-valent copper Cu 0 in the catalyst is 75 - 95 m2 / g and the average size of the catalyst's Cu particles is 7 - 10 nm, both the reaction yield and TOF are relatively high, indicating a good catalytic reaction state.

[0076] It can be seen from Table 2 that different calcination temperatures have an impact on the structure of the catalyst (specific surface area, pore size distribution, copper dispersion, copper particle size, etc.). At a calcination temperature of 450 - 600 °C, the catalyst exhibits a relatively high conversion rate and selectivity. Combining with Figure 2 the test results, at 550 °C, the size of the metallic Cu particles is 8 - 10 nm, the surface area of metallic Cu is 65.5 - 79.8 m2 / g, the specific surface area of the catalyst is 168 - 223 m2 / g, the dispersion of Cu in the catalyst is 11.1 - 13.4%, the surface area of the zero-valent copper Cu 0 in the catalyst is 75.1 - 86.9 m2 / g, and the average size of the catalyst's Cu particles is 7.5 - 9.0 nm.

[0077] Example 16

[0078] Using the calcined precursor of Example 11 as the parent body, it was impregnated with a B 2 O 3 auxiliary agent with a mass fraction of 2.5% as follows: 0.18 g of boric acid was weighed and dissolved in a certain amount of distilled water to form a solution. The 4.30 g of the calcined sample screened out in Example 11 was impregnated by equal volume, dried at 120 °C for 12 h, and then reduced and activated at 400 °C for 3 h in a hydrogen atmosphere to obtain the active catalyst 16 provided by the present invention.

[0079] Example 17

[0080] Using the calcined precursor of Example 11 as the parent body, it was impregnated with a BaO auxiliary agent with a mass fraction of 2.5%. The catalyst was prepared in the same manner as in Example 16, except that 0.18 g of barium nitrate was used instead of 0.18 g of boric acid to obtain the active catalyst 17.

[0081] Example 18

[0082] Using the calcined precursor of Example 11 as the parent body, it was impregnated with a La 2 O 3 auxiliary agent with a mass fraction of 2.5%. The catalyst was prepared in the same manner as in Example 16, except that 0.31 g of lanthanum nitrate hexahydrate was used instead of 0.18 g of boric acid to obtain the active catalyst 18.

[0083] Example 19

[0084] Using the calcined precursor of Example 11 as the matrix, impregnate with MnO with a mass fraction of 2.5% 2 as the promoter. The catalyst was prepared in the same manner as in Example 10, except that 0.20 g of manganese acetate was used instead of 0.18 g of boric acid, to obtain the active catalyst 19.

[0085] The catalyst evaluation process and operation are the same as above. The catalyst was evaluated after being recycled 8 times. The performance evaluation results of the catalyst are shown in Table 3.

[0086] Table 3: Performance evaluation of catalyst powders prepared with different promoters

[0087]

[0088] It can be seen from Table 3 that in the catalyst powder with the promoter, the Cu particles can effectively avoid sintering and aggregation and always remain between 7 and 10 nm. After 8 cycles of use, it still maintains high selectivity and high conversion rate, demonstrating the stability of the catalyst( Figure 3 ). The catalyst powder with boron oxide as the promoter has the best stability and catalytic evaluation effect.

[0089] The active catalysts obtained in Example 11 and Example 16 were respectively subjected to comparative tests in the stainless steel tubular reactor of the fixed bed reactor. The test conditions were the same as those for catalyst evaluation. After multiple cycles of reaction, the particle size of the Cu particles was measured by the method of N 2 O decomposition adsorption. Under UHV conditions, argon was used as the protective gas and N 2 O gas was gradually introduced into the reaction chamber to control its partial pressure and monitor the adsorption of N 2 O. The consumption of N 2 O could be tracked by a mass spectrometer, and the adsorption behavior of N 2 O on the copper surface was observed, and the change of the adsorption amount with time was recorded. The number of active sites on the copper surface was calculated using the coverage data and combined with the TEM image, and the particle size of the Cu particles was calculated. The change of the particle size of the Cu particles in Example 11 and Example 16 under multiple cycles of reaction is as shown in Figure 3 . It can be seen that the change in the particle size of the Cu particles with the boron oxide promoter is smaller and the catalyst is more stable.

[0090] Example 20

[0091] Based on the catalyst of Example 16 as the base powder, additive manufacturing was carried out by selective sintering technology. A three-dimensional model was established using modeling software, and a grid-like grid structure catalyst (30 mm long, 30 mm wide, 6.5 mm high) (the nine-square grid is a square with a side length of 5 mm) was printed. After cooling, surface powder treatment was carried out, and the surface was cleaned and polished to obtain catalyst 20.

[0092] Example 21

[0093] The operation is the same as that in Example 20, except that a truss structure ((30 mm in length, 30 mm in width, 6.5 mm in height)) is used to replace the grid structure to obtain Catalyst 21.

[0094] Example 22

[0095] The operation is the same as that in Example 20, except that a sphere with a radius of 15 mm is used to replace the grid structure to obtain Catalyst 22.

[0096] Example 23

[0097] The operation is the same as that in Example 20, except that a porous cube (side length of 30 cm, porosity of 65%, average pore diameter of 3.5 cm) is used to replace the grid structure to obtain Catalyst 23.

[0098] The catalyst evaluation process and operation are the same as above. The catalyst is evaluated after being recycled 8 times. The performance evaluation results of the catalyst are shown in Table 4.

[0099] Table 4: Performance evaluation of catalysts with different additive manufacturing geometries

[0100]

[0101] It can be seen from Table 4 that the catalyst with a porous structure prepared by selective sintering printing of basic powder has the highest conversion rate and product selectivity. The porous structure is very beneficial for the separation and recycling of the catalyst, which is convenient for industrial production.

[0102] Example 24

[0103] Weigh 15.00 g of copper nitrate trihydrate and stir it in 125 ml of distilled water in a beaker to obtain a copper nitrate solution. Slowly add 15 wt% NaOH solution dropwise and stir until pH > 10. After obtaining a suspension, add 16.80 g of 25% silica sol by mass to disperse and stabilize the precipitate particles, and heat to 80 °C for 3 h of aging. Dry at 120 °C for 12 h, calcine in a muffle furnace at 550 °C in a nitrogen stream for 3 h, grind and sieve (60 - 80 mesh) to obtain a calcined sample.

[0104] Weigh 0.18 g of boric acid, add a certain amount of distilled water to make a solution, impregnate 4.30 g of the sieved calcined sample with equal volume, dry at 120 °C for 12 h, and reduce and activate in a hydrogen atmosphere at 400 °C for 3 h to obtain a basic powder; use selective sintering technology for additive manufacturing, establish a three-dimensional model with modeling software, and after the porous cube (side length of 30 cm, porosity of 65%, average pore diameter of 3.5 cm) is cooled, perform surface powder treatment and surface cleaning to obtain Catalyst 24.

[0105] Example 25

[0106] Weigh 15.00 g of copper nitrate trihydrate and stir it in 125 ml of distilled water in a beaker to dissolve, obtaining a copper nitrate solution. Slowly add 15 wt% NaOH solution drop by drop and stir until the pH > 10. After obtaining a suspension, add 12.40 g of 20% silica sol by mass to disperse and stabilize the precipitate particles, and heat to 80 °C for aging for 3 h. Dry at 120 °C for 12 h, and calcine in a muffle furnace at 550 °C in a nitrogen stream for 3 h, then grind and sieve (60 - 80 mesh). Obtain the calcined sample.

[0107] Weigh 0.18 g of boric acid, add a certain amount of distilled water to make a solution, impregnate 4.30 g of the sieved calcined sample with equal volume, dry at 120 °C for 12 h, reduce and activate in a hydrogen atmosphere at 400 °C for 3 h to obtain the basic powder. Conduct additive manufacturing with selective sintering technology, establish a three-dimensional model with modeling software. After cooling the porous cube (side length 30 cm, porosity 65%, average pore diameter 3.5 cm), conduct surface powder treatment and surface cleaning to obtain Catalyst 25.

[0108] Conduct stability measurement of Catalyst 25 in the long-term catalytic hydrogenation reaction of ethylene carbonate. The measurement conditions are the same as those for the catalyst evaluation reaction. Conduct a long-term reaction by the method of supplementing ethylene carbonate and hydrogen with the separated products. This catalyst shows high selectivity, high conversion rate, and high stability. The test results are as Figure 4 . In the long-term reaction of the catalyst prepared in Example 25, the conversion rate of the raw material ethylene carbonate and the selectivity of the products methanol and ethylene glycol both remain above 93%, and the catalyst has high stability.

Claims

1. A catalyst for producing methanol and ethylene glycol from ethylene carbonate based on additive manufacturing, characterized in that: The catalyst is prepared by a precipitation gel method to prepare a catalyst additive manufacturing powder and a catalyst with a highly selective geometric shape is manufactured by a selective laser sintering technology. The general structural formula of the catalyst is Cu-M / X-PG, M is an auxiliary agent boron oxide, X is a carrier silica, PG is a preparation method of the precipitation gel method, the mass percentage of metal Cu in the catalyst is 5-75%, the mass percentage of the auxiliary agent M is 0.1-16%, and the rest is the carrier.

2. The catalyst for producing methanol and ethylene glycol from ethylene carbonate based on additive manufacturing according to claim 1, characterized in that: The particle size of metal Cu in catalyst additive manufacturing powder is 8~10nm, the surface area of ​​metal Cu in catalyst additive manufacturing powder is 65.5~79.8m² / g, the specific surface area of ​​Cu in catalyst is 168~223 m² / g, the dispersion of Cu in catalyst is 11.1~13.4%, and the zero-valent copper Cu in catalyst is 1.3~1.5%. 0 The surface area is 72.1~86.9m² / g.

3. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate to methanol based on additive manufacturing according to claim 1 or 2, characterized in that: The specific steps include: (1) stirring and mixing a copper precursor salt and pure water to obtain a copper precursor salt solution; (2) adding an alkaline agent dropwise to the copper precursor salt solution obtained in (1) at a constant rate and vigorously stirring until the pH value is greater than 10 to form a copper precursor salt suspension; (3) adding a silicon source to the copper precursor salt suspension obtained in step (2) to disperse and stabilize the precipitated colloidal particles in the copper precursor salt suspension to form a gel-like mixture; (4) aging and filtering the gelatinous mixture obtained in step (3), washing it with hot water, and then calcining it in an air atmosphere after being fully dried to obtain a catalyst precursor; (5) Pre-calcining the catalyst precursor obtained in step (4) and immersing it in an aqueous solution of boric acid (H3BO3), and then grinding and sieving to obtain a catalyst powder; (6) placing the catalyst powder obtained in step (5) into a powder cylinder of a selective sintering 3D printer, and evenly spreading the catalyst powder on a printer build platform for preheating; (7) selectively sintering and cooling the catalyst powder of step (6) by establishing a three-dimensional model according to a modeling software; (8) Take out the finished catalyst product obtained in step (7), remove the powder, clean the surface, polish it, and inspect its quality.

4. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate by producing methanol based on additive manufacturing according to claim 3, characterized in that: The copper precursor salt in step (1) is any one of copper acetate, copper nitrate, copper chloride and copper sulfate.

5. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate by producing methanol based on additive manufacturing according to claim 3, characterized in that: The alkaline agent in step (2) is any one of ammonia water, ammonium carbonate or sodium hydroxide.

6. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate by producing methanol based on additive manufacturing according to claim 3, characterized in that: The silicon source in step (3) is any one of sodium silicate and silica sol.

7. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate by producing methanol based on additive manufacturing according to claim 3, characterized in that: The preferred aging temperature of step (4) is 100°C and the aging time is 3 hours. The preferred calcination temperature is 550°C and the calcination time is 3 hours.

8. The method for preparing a catalyst for producing ethylene glycol from ethylene carbonate by producing methanol based on additive manufacturing according to claim 3, characterized in that: The geometric structure of additive manufacturing in step (7) is a porous structure.

9. According to the use of the catalyst for producing methanol and ethylene glycol from ethylene carbonate based on additive manufacturing as claimed in claim 1 or 2, the concentration of the reaction liquid of ethylene carbonate is 10-100%, tetrahydrofuran (THF) is used as the solvent of the catalytic hydrogenation reaction liquid of ethylene carbonate, the reaction conditions are reaction temperature of 140-200°C, hydrogen pressure of 2-4 MPa, reaction time of 4-8h, and the amount of catalyst used is 3-3.5g.

10. The use according to claim 9, characterized in that: The catalyst needs to be activated before use: reduction at 277-447° C. in a hydrogen atmosphere with a flow rate of 20-60 ml / min for 3-5 hours to obtain an active catalyst.

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