Cu-mn-al-y composite catalyst and preparation method and application thereof

Abstract

This invention discloses a Cu-Mn-Al-Y composite catalyst, its preparation method, and its applications. The catalyst includes a composite oxide support and Cu elemental particles supported on the composite oxide support. The composite oxide support comprises a complex formed by Al oxide and Mn oxide, with Y element doped into the complex. In this Cu-Mn-Al-Y composite catalyst, the Cu elemental particles effectively lower the activation energy of the nitrogen dioxide hydrogenation to methanol reaction. By adsorbing and activating carbon dioxide, the Cu particles weaken the carbon-oxygen double bond in carbon dioxide, making it more susceptible to accepting active hydrogen (H) from hydrogen gas, thus promoting the hydrogenation of carbon dioxide to methanol. Y doping induces lattice distortion, increasing the oxygen vacancy concentration. The introduction of Mn and Y elements increases the number of moderately alkaline sites, promoting the adsorption and activation of carbon dioxide, which helps convert the adsorbed carbon dioxide into methanol, thereby improving the methanol conversion rate.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide hydrogenation technology, and in particular to Cu-Mn-Al-Y composite catalysts, their preparation methods, and applications. Background Technology

[0002] Carbon dioxide capture, conversion, and utilization is a method to mitigate climate change and achieve carbon neutrality. It can not only address the climate security crisis caused by excessive carbon dioxide concentrations but also convert carbon dioxide into other high-value-added energy materials, such as methanol. Cu-based catalysts have the advantages of high catalytic activity, high selectivity, and low cost, and are often used in the reaction of nitrogen dioxide hydrogenation to methanol.

[0003] The reverse water-gas shift reaction also uses carbon dioxide and hydrogen as raw materials to produce carbon monoxide and water. Traditional copper-based catalysts also exhibit high catalytic activity for the reverse water-gas shift reaction. Therefore, the reverse water-gas shift reaction and the nitrogen dioxide hydrogenation to methanol reaction occur in parallel on the surface of traditional copper-based catalysts, and the two reactions compete for active sites on the catalyst surface, resulting in low selectivity for methanol. Summary of the Invention

[0004] Therefore, it is necessary to provide a Cu-Mn-Al-Y composite catalyst, its preparation method and application, with the aim of improving the selectivity of Cu-based catalysts for the hydrogenation of nitrogen dioxide to methanol.

[0005] In one aspect, the present invention provides a Cu-Mn-Al-Y composite catalyst, comprising a composite oxide support and Cu elemental particles supported on the composite oxide support, wherein the composite oxide support comprises a composite formed by oxides of Al and oxides of Mn, and the composite is doped with element Y.

[0006] The aforementioned Cu-Mn-Al-Y composite catalyst exhibits several advantages. Firstly, the active sites on the surface of Cu elemental particles effectively reduce the activation energy of the nitrogen dioxide hydrogenation to methanol reaction. By adsorbing and activating carbon dioxide, it weakens the carbon-oxygen double bond in carbon dioxide, making it more readily accepting active hydrogen (H) from hydrogen gas, thus promoting the hydrogenation of carbon dioxide to methanol. Secondly, the atomic radius of Y is much larger than that of Mn and Al. When Y is doped into the lattice of Al oxides and / or Mn oxides, it can induce local lattice distortion, increasing the oxygen vacancy concentration. The presence of oxygen vacancies enhances the conversion of carbon dioxide and reaction intermediates, promoting methanol formation. Simultaneously, the introduction of Mn and Y elements increases the number of moderately alkaline sites on the composite oxide support, promoting the adsorption and activation of carbon dioxide. Furthermore, these moderately alkaline sites facilitate the conversion of adsorbed carbon dioxide into methanol, improving the methanol conversion rate.

[0007] In one embodiment, the molar ratio of Cu, Mn, Al and Y elements in the Cu-Mn-Al-Y composite catalyst is (40~55):(1~18):(30~55):(0.3~2.5).

[0008] In one embodiment, the valence state of Mn in the oxide of Mn includes one or more of Mn(II), Mn(III) and Mn(IV).

[0009] In one embodiment, the Cu-Mn-Al-Y composite catalyst has oxygen vacancy defects.

[0010] In one embodiment, the composite oxide support further includes an oxide of Cu, wherein the valence state of Cu in the Cu oxide includes Cu(I).

[0011] In another aspect, the present invention provides a method for preparing a Cu-Mn-Al-Y composite catalyst, comprising the following steps:

[0012] A suspension containing the precursor is obtained by mixing water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, water-soluble yttrium salt, alkaline substance and solvent;

[0013] Solid-liquid separation yields the precursor;

[0014] The precursor was subjected to calcination and reduction treatments in sequence to obtain Cu-Mn-Al-Y composite catalyst.

[0015] The above-mentioned method for preparing the Cu-Mn-Al-Y composite catalyst employs a "co-precipitation + calcination + hydrogen reduction" approach to prepare a Cu-Mn-Al-Y composite catalyst comprising a composite oxide support and Cu elemental particles supported on the composite oxide support. During co-precipitation, Cu, Mn, Al, and Y ions achieve atomic-level uniform distribution, avoiding the segregation and agglomeration phenomena caused by traditional mechanical mixing methods, thus laying the foundation for subsequent calcination to form a uniform composite oxide support. The reduction treatment enables in-situ reduction of Cu elemental particles on the surface of the composite oxide support, and the Cu elemental particles are relatively uniformly dispersed. The interaction between the Cu elemental particles and the composite oxide support is strong, preventing the migration and agglomeration of Cu elemental particles and improving the catalytic activity and stability of the Cu-Mn-Al-Y composite catalyst.

[0016] In one embodiment, the molar ratio of the water-soluble copper salt, the water-soluble manganese salt, the water-soluble aluminum salt, and the water-soluble yttrium salt is (40~55):(1~18):(30~55):(0.3~2.5).

[0017] In one embodiment, the calcination treatment satisfies one or more of the following conditions:

[0018] (1) The calcination temperature is 250℃~650℃;

[0019] (2) The calcination treatment time is 0.5h~6.5h;

[0020] (3) The atmosphere for the calcination treatment is air.

[0021] In one embodiment, the reduction process satisfies one or more of the following conditions:

[0022] (1) The temperature of the reduction treatment is 175℃~425℃;

[0023] (2) The reduction treatment time is 0.5h~6.5h;

[0024] (3) The atmosphere of the reduction treatment is a mixture of hydrogen and inert gas, and the volume ratio of hydrogen to inert gas is (1~3):(7~9);

[0025] (4) The flow rate of the mixed gas in the reduction process is 10 mL / min to 80 mL / min.

[0026] Another aspect of the present invention provides a method for preparing methanol, comprising the following steps:

[0027] Methanol is prepared by reducing carbon dioxide and hydrogen under the conditions of the Cu-Mn-Al-Y composite catalyst.

[0028] The Cu-Mn-Al-Y composite catalyst includes the Cu-Mn-Al-Y composite catalyst described above or the Cu-Mn-Al-Y composite catalyst prepared by the preparation method described above.

[0029] In the above method for preparing methanol, the reverse water-gas shift reaction is suppressed, the carbon dioxide hydrogenation reaction proceeds along the path of methanol production, and the selectivity of methanol is >70%. Detailed Implementation

[0030] To facilitate understanding of the present invention, a more complete description will be given below with reference to relevant embodiments. Preferred embodiments of the invention are shown below. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the disclosure of the invention will be achieved.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] One embodiment of this application provides a Cu-Mn-Al-Y composite catalyst, comprising a composite oxide support and Cu elemental particles supported on the composite oxide support. The composite oxide support comprises a composite oxide of Al and Mn elements, wherein the Al and / or Mn elements are doped with Y.

[0033] The aforementioned Cu-Mn-Al-Y composite catalyst exhibits several advantages. Firstly, the active sites on the surface of Cu elemental particles effectively reduce the activation energy of the nitrogen dioxide hydrogenation to methanol reaction. By adsorbing and activating carbon dioxide, it weakens the carbon-oxygen double bond in carbon dioxide, making it more readily accepting active hydrogen (H) from hydrogen gas, thus promoting the hydrogenation of carbon dioxide to methanol. Secondly, the atomic radius of Y is much larger than that of Mn and Al. When Y is doped into the lattice of Al oxides and / or Mn oxides, it can induce local lattice distortion, increasing the oxygen vacancy concentration. The presence of oxygen vacancies enhances the conversion of carbon dioxide and reaction intermediates, promoting methanol formation. Simultaneously, the introduction of Mn and Y elements increases the number of moderately alkaline sites on the composite oxide support, promoting the adsorption and activation of carbon dioxide. Furthermore, these moderately alkaline sites facilitate the conversion of adsorbed carbon dioxide into methanol, improving the methanol conversion rate.

[0034] In one embodiment, the molar ratio of Cu, Mn, Al and Y elements in the Cu-Mn-Al-Y composite catalyst is (40~55):(1~18):(30~55):(0.3~2.5).

[0035] Furthermore, in the Cu-Mn-Al-Y composite catalyst, based on the total molar amount of Cu, Mn, Al and Y elements, the respective molar percentages of Cu, Mn, Al and Y elements are 40%~55%, 1%~18%, 30%~55% and 0.3%~2.5%, respectively.

[0036] The specific molar percentages of Cu, Mn, Al, and Y elements in the aforementioned Cu-Mn-Al-Y composite catalyst contribute to the formation of oxygen vacancy defects and moderately basic sites.

[0037] As an example, in the Cu-Mn-Al-Y composite catalyst, based on the total molar amount of Cu, Mn, Al and Y elements, the molar percentage of Cu can be 40%, 43%, 49%, 50%, 55% or any two of the above values, for example, 43% to 50%.

[0038] As an example, in the Cu-Mn-Al-Y composite catalyst, based on the total molar amount of Cu, Mn, Al and Y elements, the molar percentage of Mn can be 1%, 2%, 5%, 6%, 8%, 10%, 12%, 15%, 18% or any two of the above values, for example, 2% to 15%.

[0039] As an example, in the Cu-Mn-Al-Y composite catalyst, based on the total molar amount of Cu, Mn, Al and Y elements, the molar percentage of Al element can be 30%, 35%, 40%, 41%, 44.5%, 45%, 50%, 55% or any two of the above values, for example, 35%~50%.

[0040] As an example, in the Cu-Mn-Al-Y composite catalyst, based on the total molar amount of Cu, Mn, Al and Y elements, the molar percentage of Y element can be 0.3%, 0.5%, 1%, 2%, 3%, 4%, 5% or any two of the above values, for example, 0.5% to 5%.

[0041] In one embodiment, the valence state of Mn in the Mn oxide includes one or more of Mn(II), Mn(III), and Mn(IV).

[0042] In the aforementioned Cu-Mn-Al-Y composite catalyst, the Mn element in the composite oxide support has multiple valence states such as Mn(II), Mn(III), and Mn(IV), which can regulate the electronic state of Cu elemental particles. This allows the adsorption and desorption strength of the active sites on the Cu elemental particles for the intermediates of the carbon dioxide hydrogenation reaction to be moderate, avoiding poisoning of active sites due to excessive adsorption or reduction of catalytic activity due to insufficient adsorption.

[0043] In one embodiment, the Cu-Mn-Al-Y composite catalyst has oxygen vacancy defects.

[0044] In the aforementioned Cu-Mn-Al-Y composite catalyst, the presence of oxygen vacancies promotes the activation of carbon dioxide into the *HCOO intermediate and significantly reduces the energy barrier for the conversion of the *HCOO intermediate to *H2CO, thereby improving the selectivity of carbon dioxide hydrogenation to methanol. Simultaneously, oxygen vacancies stabilize Cu particles, enhancing the interaction between the composite oxide support and the Cu particles, reducing the migration and aggregation tendency of Cu particles, thus ensuring the stability of the Cu-Mn-Al-Y composite catalyst.

[0045] Furthermore, the composite oxide support includes a composite oxide formed from oxides of Al, oxides of Mn, and oxides of Cu, i.e., the composite oxide includes oxides of Cu.

[0046] In one embodiment, the composite oxide support further includes an oxide of Cu, wherein the valence state of Cu in the oxide of Cu includes Cu(I).

[0047] In the aforementioned Cu-Mn-Al-Y composite catalyst, the Cu(Ⅰ) site can stabilize the *CO intermediate and promote the gradual hydrogenation of the *CO intermediate into methanol. The Cu(Ⅰ) site can work synergistically with the active site of elemental Cu to improve the selectivity of methanol.

[0048] Another embodiment of this application provides a method for preparing a Cu-Mn-Al-Y composite catalyst, comprising the following steps:

[0049] A suspension containing the precursor is obtained by mixing water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, water-soluble yttrium salt, alkaline substance and solvent;

[0050] Solid-liquid separation yields the precursor;

[0051] The precursor was subjected to calcination and reduction treatments in sequence to obtain Cu-Mn-Al-Y composite catalyst.

[0052] The above-mentioned method for preparing the Cu-Mn-Al-Y composite catalyst employs a "co-precipitation + calcination + hydrogen reduction" approach to prepare a Cu-Mn-Al-Y composite catalyst comprising a composite oxide support and Cu elemental particles supported on the composite oxide support. During co-precipitation, Cu, Mn, Al, and Y ions achieve atomic-level uniform distribution, avoiding the segregation and agglomeration phenomena caused by mechanical mixing methods, thus laying the foundation for subsequent calcination to form a uniform composite oxide support. The reduction treatment enables in-situ reduction of Cu elemental particles on the surface of the composite oxide support, and the Cu elemental particles are relatively uniformly dispersed. The interaction between the Cu elemental particles and the composite oxide support is strong, thereby preventing the migration and agglomeration of Cu elemental particles and improving the catalytic activity and stability of the Cu-Mn-Al-Y composite catalyst.

[0053] In one embodiment, the molar ratio of water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, and water-soluble yttrium salt is (40~55):(1~18):(30~55):(0.3~5).

[0054] Furthermore, based on the total molar amount of copper in water-soluble copper salts, manganese in water-soluble manganese salts, aluminum in water-soluble aluminum salts, and yttrium in water-soluble yttrium salts, the respective molar amounts of copper, manganese, aluminum, and yttrium are 40%~55%, 1%~18%, 30%~55%, and 0.3%~2.5%, respectively.

[0055] In one embodiment, based on the total molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt, the molar amount of copper in the water-soluble copper salt is 40% to 55%. As an example, the molar amount of copper in the water-soluble copper salt can be 40%, 43%, 49%, 50%, 55%, or any two of the above values, for example, 43% to 50%.

[0056] In one embodiment, based on the total molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt, the molar amount of manganese in the water-soluble manganese salt is 1% to 18%. As an example, the molar amount of manganese in the water-soluble manganese salt can be 1%, 2%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, or any two of the above values, for example, 2% to 15%.

[0057] In one embodiment, based on the total molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt, the molar amount of copper in the water-soluble copper salt is 30% to 55%. As an example, the molar amount of aluminum in the water-soluble aluminum salt can be 30%, 35%, 40%, 41%, 44.5%, 45%, 50%, 55%, or any two of the above values, for example, 35% to 50%.

[0058] In one embodiment, based on the total molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt, the molar amount of manganese in the water-soluble manganese salt is 0.3% to 5%. As an example, the molar amount of yttrium in the water-soluble yttrium salt can be 0.3%, 0.5%, 1%, 2%, 3%, 4%, 5%, or any two of the above values, for example, 0.5% to 5%.

[0059] In one embodiment, the water-soluble copper salt includes one or more of copper nitrate, copper chloride, and copper sulfate.

[0060] In one embodiment, the water-soluble manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese sulfate.

[0061] In one embodiment, the water-soluble aluminum salt includes one or more of aluminum nitrate and aluminum chloride.

[0062] In one embodiment, the water-soluble yttrium salt includes one or more of yttrium nitrate and yttrium chloride.

[0063] In one embodiment, the solvent includes one or more of methanol, ethanol, isopropanol, and water.

[0064] In one embodiment, the calcination temperature is 250°C to 650°C. As an example, the calcination temperature may be 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, or any two of the above values, for example, 300°C to 600°C.

[0065] In one embodiment, the calcination time is 0.5h to 6.5h. As an example, the calcination time can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, or any two of the above values, for example, 1h to 6h.

[0066] In one embodiment, the calcination atmosphere is air.

[0067] In one embodiment, the reduction treatment temperature is 175°C to 425°C. As an example, the reduction treatment temperature may be 175°C, 200°C, 250°C, 300°C, 350°C, 400°C, 425°C, or any two of the above values, such as 200°C to 400°C.

[0068] In one embodiment, the restoration process takes 0.5h to 6.5h. As an example, the restoration process can take 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, or any two of the above values, for example, 1h to 6h.

[0069] In one embodiment, the atmosphere for the reduction process is a mixture of hydrogen and an inert gas, with a volume ratio of hydrogen to inert gas of (1~3):(7~9). As an example, the volume ratio of hydrogen to inert gas can be 3:7, 2:8, 1:9, or any two of the above values.

[0070] In one embodiment, the flow rate of the mixed gas in the reduction process is 10 mL / min to 80 mL / min. As an example, the flow rate of the mixed gas in the reduction process may be 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, or any two of the above values.

[0071] In one embodiment, mixing a water-soluble copper salt, a water-soluble manganese salt, a water-soluble aluminum salt, a water-soluble yttrium salt, an alkaline substance, and a solvent includes the following steps:

[0072] A mixed salt solution is obtained by mixing water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, and water-soluble yttrium salt with a solvent.

[0073] An alkaline solution is obtained by mixing an alkaline substance with a solvent.

[0074] The mixed salt solution and the alkaline solution are slowly mixed to obtain a suspension with a pH of 9-13.

[0075] In one embodiment, the mixed salt solution and the alkaline solution are slowly mixed at a temperature of 200°C to 400°C.

[0076] In one embodiment, the total molar concentration of the water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, and water-soluble yttrium salt in the mixed salt solution is 0.5 mol / L to 3 mol / L. As an example, the total molar concentration of the water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, and water-soluble yttrium salt can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, or any two of the above values ​​within a range.

[0077] In one embodiment, the molar concentration of the alkaline substance in the alkaline solution is 0.5 mol / L to 3 mol / L. As an example, the molar concentration of the alkaline substance can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, or any two of the above values.

[0078] In one embodiment, the mixed salt solution and the alkaline solution are mixed in a volume ratio of 1:1 to 1:1.3.

[0079] In one embodiment, the alkaline substance includes one or more of sodium carbonate, sodium bicarbonate, ammonium carbonate, sodium hydroxide, gaseous ammonia, and ammonium bicarbonate.

[0080] Optionally, the alkaline substance includes sodium carbonate and sodium bicarbonate; the molar ratio of sodium carbonate to sodium bicarbonate is 1:(0.5~2).

[0081] Optionally, the alkaline substance includes sodium carbonate and sodium hydroxide; the molar ratio of sodium carbonate to sodium hydroxide is 1:(0.3~0.5).

[0082] Optionally, alkaline substances include gaseous ammonia.

[0083] Optionally, the alkaline substances include sodium hydroxide and ammonium bicarbonate; the molar ratio of sodium hydroxide to ammonium bicarbonate is 1:(1~3).

[0084] Optionally, alkaline substances include sodium carbonate.

[0085] Another embodiment of this application provides a method for preparing methanol, comprising the following steps:

[0086] Methanol is prepared by reducing carbon dioxide and hydrogen under the conditions of Cu-Mn-Al-Y composite catalyst.

[0087] Cu-Mn-Al-Y composite catalysts include the above-mentioned Cu-Mn-Al-Y composite catalysts or Cu-Mn-Al-Y composite catalysts prepared by the above-mentioned preparation method.

[0088] In the above method for preparing methanol, the reverse water-gas shift reaction is suppressed, the carbon dioxide hydrogenation reaction proceeds along the path of methanol production, and the selectivity of methanol is >70%.

[0089] In one embodiment, the molar ratio of carbon dioxide to hydrogen is (2~4):1. As an example, the molar ratio of carbon dioxide to hydrogen can be 2:1, 3:1, 4:1, or any two of the above values.

[0090] In one embodiment, the pressure of the reduction reaction is 3 MPa to 6.5 MPa. As an example, the pressure of the reduction reaction may be 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, or any two of the above values, for example, 3.5 MPa to 6 MPa.

[0091] In one embodiment, the reduction reaction temperature is 230°C to 300°C. As an example, the reduction reaction temperature may be 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or any two of the above values, for example, 240°C to 290°C.

[0092] In one embodiment, the space velocity of the reduction reaction is 3000 h⁻¹. -1 ~15000h-1 As an example, the space velocity for a reduction reaction can be 3000 h⁻¹. -1 4000h -1 5000h -1 6000h -1 7000h -1 8000h -1 9000h -1 10000h -1 11000h -1 12000h -1 13000h -1 14000h -1 15000h -1 Or within the range formed by any two of the above values.

[0093] In one embodiment, the reduction reaction is carried out in a fixed-bed reactor.

[0094] In one embodiment, the fixed-bed reactor includes a reactor and a stainless steel tube inside the reactor. The stainless steel tube is filled with a Cu-Mn-Al-Y composite catalyst. Carbon dioxide and hydrogen are introduced into the stainless steel tube, and the reactor heats the Cu-Mn-Al-Y composite catalyst, carbon dioxide, and hydrogen inside the stainless steel tube.

[0095] The following are specific examples.

[0096] Example 1

[0097] S1. Coprecipitation. Weigh water-soluble copper nitrate, 50 wt% manganese nitrate solution, water-soluble aluminum nitrate, and water-soluble yttrium nitrate in a Cu:Mn:44.5:0.5 molar ratio of Cu:10:44.5:0.5, and dissolve them in 500 mL of deionized water to obtain a mixed salt solution. Weigh 106 g of sodium carbonate and 126 g of sodium bicarbonate in a 1:1.5 molar ratio, and dissolve them in 500 mL of deionized water to obtain an alkaline solution. At 70 °C, mix the mixed salt solution and the alkaline solution in a 1:1 volume ratio to form a suspension containing the precursor, and let it stand at 70 °C for 12 h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 70 °C for 12 h.

[0098] S2. Calcination treatment. The dried precursor was calcined at 350℃ for 6 hours in air atmosphere, with a heating rate of 5℃ / min.

[0099] S3. Reduction treatment. The calcined precursor was kept at 300℃ for 5h in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen gas integral of 20% and a heating rate of 5℃ / min, to obtain the Cu-Mn-Al-Y composite catalyst.

[0100] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube is filled with quartz sand. 1g of Cu-Mn-Al-Y composite catalyst is added to the stainless steel tube. The other end of the stainless steel tube is also filled with quartz sand to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas is introduced into the stainless steel tube at a pressure of 5MPa, a temperature of 250℃, and a gas hourly space velocity of 4000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0101] Example 2

[0102] The preparation method of Example 2 is basically the same as that of Example 1, except that the molar ratio of each element in the Cu-Mn-Al-Y composite catalyst, the type and proportion of alkaline substances, the process parameters of co-precipitation, the process parameters of calcination treatment, the process parameters of reduction treatment, and the process parameters of carbon dioxide hydrogenation reaction are not exactly the same.

[0103] Right now:

[0104] S1. Coprecipitation. Weigh water-soluble copper chloride, 50wt% manganese nitrate solution, water-soluble aluminum sulfate, and water-soluble yttrium chloride in a Cu:Mn:Al:35:5 molar ratio, and dissolve them in 500mL of deionized water to obtain a mixed salt solution. Weigh 106g of sodium carbonate and 20g of sodium hydroxide in a 1:0.5 molar ratio, and dissolve them in 500mL of deionized water to obtain an alkaline solution. At 30℃, mix the mixed salt solution and the alkaline solution in a 1:1.2 volume ratio to form a suspension containing the precursor, and let it stand at 60℃ for 18h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 80℃ for 12h.

[0105] S2. Calcination treatment. The dried precursor is calcined at 600℃ for 1 hour in air atmosphere.

[0106] S3. Reduction treatment. The calcined precursor was kept at 400℃ for 1 hour in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen gas integral of 30%, to obtain the Cu-Mn-Al-Y composite catalyst.

[0107] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube was filled with quartz sand. 1.2g of Cu-Mn-Al-Y composite catalyst was added to the stainless steel tube, and the other end of the tube was also filled with quartz sand to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas was introduced into the stainless steel tube at a pressure of 4MPa, a temperature of 240℃, and a gas hourly space velocity of 8000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0108] Example 3

[0109] The preparation method of Example 3 is basically the same as that of Example 1, except that the molar ratio of each element in the Cu-Mn-Al-Y composite catalyst, the type and proportion of alkaline substances, the process parameters of co-precipitation, the process parameters of calcination treatment, the process parameters of reduction treatment, and the process parameters of carbon dioxide hydrogenation reaction are not exactly the same.

[0110] Right now:

[0111] S1. Coprecipitation. Weigh water-soluble copper sulfate, 50% manganese nitrate solution, water-soluble aluminum chloride, and water-soluble yttrium nitrate in a Cu:Mn:Al:Y molar ratio of 49:8:41:2, and dissolve them in 500 mL of deionized water to obtain a mixed salt solution. At 50°C, mix the mixed salt solution with 25 wt% ammonia water at a volume ratio of 1:1.5 to form a suspension containing the precursor, and let it stand at 40°C for 11 h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 80°C for 12 h.

[0112] S2. Calcination treatment. The dried precursor is calcined at 450℃ for 3 hours in air atmosphere.

[0113] S3. Reduction treatment. The calcined precursor was kept at 300℃ for 6 hours in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen gas integral of 10%, to obtain the Cu-Mn-Al-Y composite catalyst.

[0114] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube was filled with quartz sand. 1.5g of Cu-Mn-Al-Y composite catalyst was added to the stainless steel tube, and the other end was also filled with quartz sand to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas was introduced into the stainless steel tube at a pressure of 6MPa, a temperature of 260℃, and a gas hourly space velocity of 10000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0115] Example 4

[0116] The preparation method of Example 4 is basically the same as that of Example 1, except that the molar ratio of each element in the Cu-Mn-Al-Y composite catalyst, the type and proportion of alkaline substances, the process parameters of co-precipitation, the process parameters of calcination treatment, the process parameters of reduction treatment, and the process parameters of carbon dioxide hydrogenation reaction are not exactly the same.

[0117] Right now:

[0118] S1. Coprecipitation. Weigh water-soluble copper chloride (Cu, Mn, Al, Y) and 50 wt% manganese nitrate solution, water-soluble aluminum nitrate (Aluminum nitrate), and water-soluble yttrium chloride (Yttrium) in a Cu:10:35:5 molar ratio, and dissolve them in 1000 mL of deionized water to obtain a mixed salt solution. Weigh 106 g of sodium hydroxide and 158 g of ammonium bicarbonate in a 1:2 molar ratio, and dissolve them in 800 mL of deionized water to obtain an alkaline solution. At 65 °C, mix the mixed salt solution and the alkaline solution in a 1:1.25 volume ratio to form a suspension containing the precursor, and let it stand at 55 °C for 10 h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 80 °C for 12 h.

[0119] S2. Calcination treatment. The dried precursor is calcined at 500℃ for 5 hours in air atmosphere.

[0120] S3. Reduction treatment. The calcined precursor was kept at 200℃ for 6 hours in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen integral of 30%, to obtain the Cu-Mn-Al-Y composite catalyst.

[0121] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube was filled with quartz sand. 1.25g of Cu-Mn-Al-Y composite catalyst was added to the stainless steel tube, and the other end of the tube was also filled with quartz sand to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas was introduced into the stainless steel tube at a pressure of 3.5MPa, a temperature of 290℃, and a gas hourly space velocity of 15000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0122] Example 5

[0123] The preparation method of Example 5 is basically the same as that of Example 1, except that the molar ratio of each element in the Cu-Mn-Al-Y composite catalyst, the type and proportion of alkaline substances, the process parameters of co-precipitation, the process parameters of calcination treatment, the process parameters of reduction treatment, and the process parameters of carbon dioxide hydrogenation reaction are not exactly the same.

[0124] Right now:

[0125] S1. Coprecipitation. Weigh water-soluble copper chloride, 50 wt% manganese nitrate solution, water-soluble aluminum sulfate, and water-soluble yttrium nitrate in a Cu:Mn:Al:Y molar ratio of 43:5:50:1, and dissolve them in 700 mL of deionized water to obtain a mixed salt solution. Weigh 106 g of sodium carbonate and 42 g of sodium bicarbonate in a 1:0.5 molar ratio, and dissolve them in 400 mL of deionized water to obtain an alkaline solution. At 40 °C, mix the mixed salt solution and the alkaline solution in a volume ratio of 1.25:1 to form a suspension containing the precursor, and let it stand at 60 °C for 5 h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 80 °C for 12 h.

[0126] S2. Calcination treatment. The dried precursor is calcined at 400℃ for 2 hours in air atmosphere.

[0127] S3. Reduction treatment. The calcined precursor was kept at 350℃ for 4 hours in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen integral of 30%, to obtain the Cu-Mn-Al-Y composite catalyst.

[0128] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube was filled with quartz sand. 1.5g of Cu-Mn-Al-Y composite catalyst was added to the stainless steel tube, and the other end of the tube was also filled with quartz sand to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas was introduced into the stainless steel tube at a pressure of 5.5MPa, a temperature of 270℃, and a gas hourly space velocity of 5000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0129] Example 6

[0130] The preparation method of Example 6 is basically the same as that of Example 1, except that the molar ratio of each element in the Cu-Mn-Al-Y composite catalyst, the type and proportion of alkaline substances, the process parameters of co-precipitation, the process parameters of calcination treatment, the process parameters of reduction treatment, and the process parameters of carbon dioxide hydrogenation reaction are not exactly the same.

[0131] Right now:

[0132] S1. Coprecipitation. Weigh water-soluble copper sulfate, 50wt% manganese nitrate solution, water-soluble aluminum nitrate, and water-soluble yttrium nitrate in a Cu:Mn:Al:Y molar ratio of 49:2:45:4, and dissolve them in 600 mL of deionized water to obtain a mixed salt solution. Weigh 53 g of sodium carbonate and dissolve it in 1000 mL of deionized water to obtain an alkaline solution. At 55 °C, mix the mixed salt solution and the alkaline solution in a volume ratio of 1:1.3 to form a suspension containing the precursor, and let it stand at 65 °C for 2 h. Separate the solid and liquid phases to obtain the precursor. Wash the precursor with deionized water until the washings are neutral, and then dry it at 80 °C for 12 h.

[0133] S2. Calcination treatment. The dried precursor is calcined at 300℃ for 6 hours in air atmosphere.

[0134] S3. Reduction treatment. The calcined precursor was kept at 275℃ for 4.5h in a mixed atmosphere of hydrogen and nitrogen, with a hydrogen gas integral of 20%, to obtain the Cu-Mn-Al-Y composite catalyst.

[0135] S4. Carbon dioxide hydrogenation reaction. One end of a stainless steel tube is filled with quartz sand. 1g of Cu-Mn-Al-Y composite catalyst is added into the stainless steel tube. The other end of the stainless steel tube is also filled with quartz wool to fix the Cu-Mn-Al-Y composite catalyst. A mixture of carbon dioxide and hydrogen gas is introduced into the stainless steel tube at a pressure of 5.5MPa, a temperature of 280℃, and a gas hourly space velocity of 6000h⁻¹. -1 The molar ratio of hydrogen to carbon dioxide is 3:1.

[0136] Comparative Example 1

[0137] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the Y element is omitted in the Cu-Mn-Al-Y composite catalyst, that is, the prepared catalyst is a Cu-Mn-Al composite catalyst, wherein the molar ratio of Cu, Mn and Al is 45.2:10.1:44.7.

[0138] Comparative Example 2

[0139] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the reduction treatment step is omitted. That is, the Cu-Mn-Al-Y composite catalyst is a composite oxide, which is a composite oxide of Cu, Mn, Al and Y elements. There are no Cu elemental particles obtained by reduction treatment on the composite oxide. All Cu elements in the Cu-Mn-Al-Y composite catalyst exist in the state of oxide.

[0140] The proportions of water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, and water-soluble yttrium salt used in the preparation methods of each embodiment and comparative example are shown in Table 1. In Table 1, Cu (mol%) refers to the percentage of the molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt, based on the total molar amount of copper in the water-soluble copper salt, manganese in the water-soluble manganese salt, aluminum in the water-soluble aluminum salt, and yttrium in the water-soluble yttrium salt. The others are similar.

[0141] Table 1

[0142] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Cu (mol%) 45 45 49 50 43 49 45.2 45 Mn (mol%) 10 15 8 10 6 2 10.1 10 Al (mol%) 44.5 35 41 35 50 45 44.7 44.5 Y(mol%) 0.5 5 2 5 1 5 / 0.5

[0143] The products obtained in each embodiment and comparative example were analyzed by chromatography, and the conversion rate of carbon dioxide was calculated. ), selectivity of methanol ) and the selectivity of carbon monoxide ( ), and the specific catalytic performance is shown in Table 2;

[0144] in, The calculation formula is , The calculation formula is , The calculation formula is ;

[0145] In the formula, This indicates the amount of carbon dioxide at the inlet of the stainless steel pipe. , and These represent the amounts of carbon dioxide, methanol, and carbon monoxide at the outlet of the stainless steel pipe, respectively.

[0146] Table 2

[0147] (%) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 20.9 18.7 15.9 11.8 22.6 23.6 13.8 9.4 72.1 78.1 83.6 80.5 82.8 86.3 60.5 56.2 27.9 21.9 16.4 19.5 17.2 16.7 39.5 43.8

[0148] As can be seen from Examples 1 to 6 and Tables 1 to 2, the carbon dioxide conversion rate of Examples 1 to 6 is all >10%, the selectivity of methanol is all >70%, and the selectivity of carbon monoxide is all <28%, indicating that the catalyst system of Cu-Mn-Al-Y composite catalyst has high selectivity for methanol and can suppress the generation of carbon monoxide.

[0149] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A Cu-Mn-Al-Y composite catalyst, characterized in that, It includes a composite oxide support and Cu elemental particles supported on the composite oxide support. The composite oxide support comprises a composite formed by oxides of Al and oxides of Mn, and the composite is doped with Y element.

2. The Cu-Mn-Al-Y composite catalyst as described in claim 1, characterized in that, In the Cu-Mn-Al-Y composite catalyst, the molar ratio of Cu, Mn, Al and Y is (40~55):(1~18):(30~55):(0.3~2.5).

3. The Cu-Mn-Al-Y composite catalyst as described in claim 1, characterized in that, The oxidation states of Mn in the oxides of Mn include one or more of Mn(II), Mn(III), and Mn(IV).

4. The Cu-Mn-Al-Y composite catalyst as described in claim 1, characterized in that, The Cu-Mn-Al-Y composite catalyst has oxygen vacancy defects.

5. The Cu-Mn-Al-Y composite catalyst according to any one of claims 1 to 4, characterized in that, The composite oxide support also includes Cu oxide, wherein the Cu element in the Cu oxide has a valence state including Cu(Ⅰ).

6. A method for preparing a Cu-Mn-Al-Y composite catalyst, characterized in that, Includes the following steps: A suspension containing the precursor is obtained by mixing water-soluble copper salt, water-soluble manganese salt, water-soluble aluminum salt, water-soluble yttrium salt, alkaline substance and solvent; Solid-liquid separation yields the precursor; The precursor was subjected to calcination and reduction treatments in sequence to obtain the Cu-Mn-Al-Y composite catalyst.

7. The preparation method of the Cu-Mn-Al-Y composite catalyst as described in claim 6, characterized in that, The molar ratio of Cu in the water-soluble copper salt, Mn in the water-soluble manganese salt, Al in the water-soluble aluminum salt, and Y in the water-soluble yttrium salt is (40~55):(1~18):(30~55):(0.3~5).

8. The preparation method of the Cu-Mn-Al-Y composite catalyst as described in claim 6, characterized in that, The calcination treatment satisfies one or more of the following conditions: (1) The calcination temperature is 250℃~650℃; (2) The calcination treatment time is 0.5h~6.5h; (3) The atmosphere for the calcination treatment is air.

9. The preparation method of the Cu-Mn-Al-Y composite catalyst as described in claim 6, characterized in that, The reduction process satisfies one or more of the following conditions: (1) The temperature of the reduction treatment is 175℃~425℃; (2) The reduction treatment time is 0.5h~6.5h; (3) The atmosphere of the reduction treatment is a mixture of hydrogen and inert gas, and the volume ratio of hydrogen to inert gas is (1~3):(7~9); (4) The flow rate of the mixed gas in the reduction process is 10 mL / min to 80 mL / min.

10. A method for preparing methanol, characterized in that, Includes the following steps: Methanol is prepared by reducing carbon dioxide and hydrogen under the conditions of the Cu-Mn-Al-Y composite catalyst. The Cu-Mn-Al-Y composite catalyst includes the Cu-Mn-Al-Y composite catalyst as described in any one of claims 1 to 5 or the Cu-Mn-Al-Y composite catalyst prepared by the preparation method described in any one of claims 6 to 8.