Alkaline-earth metal modified copper-based catalyst, preparation method thereof and application of alkaline-earth metal modified copper-based catalyst in preparation of methanol by hydrogenation of carbon dioxide

Abstract

The invention discloses an alkaline earth metal modified copper-based catalyst and a preparation method and application thereof in preparation of methanol by hydrogenation of carbon dioxide, and relates to the technical field of catalysts, the preparation method of the catalyst comprises the following steps: fully grinding and mixing strontium acetate, cupric acetate monohydrate, zinc acetate dihydrate, zirconium acetate and anhydrous oxalic acid, and drying at high temperature to obtain the alkaline earth metal modified copper-based catalyst. And carrying out high-temperature calcination for a period of time, and naturally cooling to obtain the product. And tabletting and granulating the product to obtain the alkaline earth metal modified copper-based catalyst. The alkaline earth metal modified copper-based catalyst provided by the invention has the advantages of good catalytic activity, high selectivity and the like in a reaction for preparing methanol through carbon dioxide hydrogenation; in a carbon dioxide hydrogenation process, the alkaline earth metal modified copper-based catalyst can obtain 6.2% of CO2 conversion rate and 93% of methanol selectivity at a low temperature of 160 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an alkaline earth metal-modified copper-based catalyst, a preparation method thereof, and application thereof in producing methanol by hydrogenating carbon dioxide. Background Art

[0002] Methanol, as a basic organic chemical raw material, can be used to prepare a variety of organic chemical products, including formic acid, methyl formate, and acetic acid. With rapid economic development and increasing energy scarcity, the application of methanol in automotive fuel and fuel cells has enormous potential and promising development prospects.

[0003] The commonly used catalyst for CO2 hydrogenation to methanol is Cu-ZnO-Al2O3, in which Cu and ZnO are active phases and Al2O3 is a structural additive. However, this catalyst is unstable during use and easily loses activity through sintering or loss, resulting in a short service life and poor stability. Summary of the Invention

[0004] In view of this, the present invention provides an alkaline earth metal-modified copper-based catalyst, a preparation method thereof, and an application thereof in the hydrogenation of carbon dioxide to methanol, which has the advantages of good catalytic activity and high selectivity in the reaction of hydrogenating carbon dioxide to methanol.

[0005] The invention provides an alkaline earth metal-modified copper-based catalyst. The raw materials for preparing the copper-based catalyst include: strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate and anhydrous oxalic acid, and the ratio is (0.1-0.2) g: (5-15) mmol: (2-5): mmol: (2-5) mmol: (40-100) mmol.

[0006] At the same time, the present invention also provides a method for preparing the catalyst, which specifically comprises the following steps:

[0007] Thoroughly grinding and mixing strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate, and anhydrous oxalic acid at room temperature, uniformly heating to the first temperature, and then maintaining the temperature for a period of time to obtain a second mixture;

[0008] uniformly heating the second mixture to a second temperature and keeping the temperature for a period of time, and then naturally cooling the mixture to obtain an alkaline earth metal-modified copper-based catalyst;

[0009] Wherein, the first temperature is 100-140°C, and the second temperature is 350-450°C.

[0010] Preferably, the heating rate for uniform heating to the first temperature is 5°C / min to 15°C / min, and the heating rate for uniform heating to the second temperature is 5°C / min to 15°C / min.

[0011] Preferably, the holding time for heating to the first temperature is 10 hours to 14 hours, and the holding time for heating to the second temperature is 2 hours to 4 hours.

[0012] The present invention also provides an application method of the catalyst. The copper-based catalyst is used in the reaction of preparing methanol by hydrogenating CO2.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The alkaline earth metal-modified copper-based catalyst provided by the present invention has the advantages of good catalytic activity and high selectivity in the reaction of preparing methanol by hydrogenation of carbon dioxide, and has industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the XRD pattern of the copper-based catalyst of Example 1 of the present invention;

[0016] Figure 2 1 is a catalytic performance diagram of the copper-based catalyst of Example 1 of the present invention;

[0017] Figure 3 The XRD pattern of the copper-based catalyst of Example 2 of the present invention;

[0018] Figure 4 Graph showing the catalytic performance of the copper-based catalyst of Example 2 of the present invention;

[0019] Figure 5 The XRD pattern of the copper-based catalyst of Example 3 of the present invention;

[0020] Figure 6 : is a catalytic performance diagram of the copper-based catalyst of Example 3 of the present invention;

[0021] Figure 7 The XRD pattern of the copper-based catalyst of Comparative Example 1 of the present invention;

[0022] Figure 8 This is a catalytic performance diagram of the copper-based catalyst of Comparative Example 1 of the present invention;

[0023] Figure 9 The XRD pattern of the copper-based catalyst of Comparative Example 2 of the present invention;

[0024] Figure 10 This is a catalytic performance diagram of the copper-based catalyst of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. However, the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present invention thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity, and like reference numerals denote like elements throughout.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0027] The invention provides an alkaline earth metal-modified copper-based catalyst. The raw materials for preparing the copper-based catalyst include: strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate and anhydrous oxalic acid, with a ratio of (0.1-0.2) g: (5-15) mmol: (2-5) mmol: (2-5) mmol: (40-100) mmol.

[0028] At the same time, the present invention also provides a method for preparing the catalyst, which specifically comprises the following steps:

[0029] Thoroughly grinding and mixing strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate, and anhydrous oxalic acid at room temperature, uniformly heating to the first temperature, and then maintaining the temperature for a period of time to obtain a second mixture;

[0030] uniformly heating the second mixture to a second temperature and keeping the temperature for a period of time, and then naturally cooling the mixture to obtain an alkaline earth metal-modified copper-based catalyst;

[0031] Wherein, the first temperature is 100-140°C, and the second temperature is 350-450°C.

[0032] Preferably, the heating rate for uniform heating to the first temperature is 5°C / min to 15°C / min, and the heating rate for uniform heating to the second temperature is 5°C / min to 15°C / min.

[0033] Preferably, the holding time for heating to the first temperature is 10 hours to 14 hours, and the holding time for heating to the second temperature is 2 hours to 4 hours.

[0034] The present invention also provides an application method of the catalyst. The copper-based catalyst is used in the reaction of preparing methanol by hydrogenating CO2.

[0035] The following test methods are provided for the catalyst to verify its performance.

[0036] Specifically, the CO2 hydrogenation to methanol reaction was carried out in a fixed-bed reactor at 50 bar pressure and 160°C. The catalyst was loaded into a fixed-bed reactor with an inner diameter of 9 mm. Subsequently, 50 bar of reaction gas (72 vol% H2, 24 vol% CO2, and 4 vol% Ar, with Ar as an internal standard) was introduced as feed gas at a flow rate of 40 mL min-1.

[0037] The present invention uses two gas chromatographs to monitor products and reactants online. H₂, CO, CO₂, CH₄, and Ar₂ are analyzed using a carbon molecular sieve column (TDX-1) with a thermal conductivity detector (TCD). CH₄ and CH₃OH are analyzed using a PLOT-Q column with a flame ionization detector (FID), with CH₄ serving as a reference bridge between the TCD and FID. The CO₂ conversion rate is calculated using the internal standard method, assuming the amount of Ar₂ remains constant after the reaction.

[0038] The CO2 conversion rate is calculated based on carbon atoms using the following formula:

[0039] CO2 conversion rate = (CO2inlet-CO2outlet) / CO2inlet×100%;

[0040] Among them, CO2inlet and CO2outlet are the molar numbers of CO2 at the inlet and outlet respectively.

[0041] The following schematically illustrates the preparation method of the designed alkaline earth metal-modified copper-based catalyst and its application in the CO2 hydrogenation reaction to produce methanol. It should be noted that this example is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention.

[0042] Example 1

[0043] The preparation method of the alkaline earth metal modified copper-based catalyst is as follows:

[0044] First, 0.1 g of strontium acetate, 5 mmol of copper acetate monohydrate, 2 mmol of zinc acetate dihydrate, 2 mmol of zirconium acetate and 40 mmol of anhydrous oxalic acid were mixed at room temperature, and the mixture was fully ground and mixed at room temperature. Then, the mixture was heated to 120°C in an oven at a heating rate of 10°C / min, kept warm and dried for 12 hours, and the obtained product was further heated to 400°C in a muffle furnace at a heating rate of 5°C / min and maintained for 3 hours. After naturally cooling to room temperature, the product was obtained.

[0045] The prepared alkaline earth metal-modified copper-based catalyst was tested for carbon dioxide hydrogenation performance:

[0046] 2g of the prepared alkaline earth metal-modified copper-based catalyst was loaded into a fixed bed and fed with a mixture of carbon dioxide and hydrogen. The mixture contained 4% by volume of argon as an internal standard for calculating conversion and selectivity. The volume ratio of carbon dioxide to hydrogen in the mixture was 1:3. The reaction was carried out continuously at 160°C, 50 bar, and 40 mL / min. The reaction exhaust passed through a fully insulated needle valve and heated pipe before entering a gas chromatograph for online analysis. After 5 hours of reaction, the carbon dioxide conversion reached 6.2%, while the methanol selectivity reached 93%.

[0047] Figure 1 1 is the XRD pattern of the copper-based catalyst according to Example 1 of the present invention.

[0048] Figure 2 Graph showing the catalytic performance of the copper-based catalyst according to Example 1 of the present invention.

[0049] Example 2

[0050] The difference from Example 1 is that the catalyst raw material ratio is adjusted to a mixture of 0.2 g strontium acetate, 15 mmol copper acetate monohydrate, 5 mmol zinc acetate dihydrate, 5 mmol zirconium acetate and 100 mmol anhydrous oxalic acid.

[0051] The prepared alkaline earth metal-modified copper-based catalyst was tested for carbon dioxide hydrogenation performance:

[0052] 2g of the prepared alkaline earth metal-modified copper-based catalyst was loaded into a fixed bed and fed with a mixture of carbon dioxide and hydrogen. The mixture contained 4% by volume of argon as an internal standard for calculating conversion and selectivity. The volume ratio of carbon dioxide to hydrogen in the mixture was 1:3. The reaction was carried out continuously at 160°C, 50 bar, and 40 mL / min. The reaction exhaust passed through a fully insulated needle valve and heated pipe before entering a gas chromatograph for online analysis. After 5 hours of reaction, the carbon dioxide conversion reached 5.5%, while the methanol selectivity reached 91%.

[0053] Figure 3 1 is the XRD pattern of the copper-based catalyst according to Example 2 of the present invention.

[0054] Figure 4 Graph showing the catalytic performance of the copper-based catalyst according to Example 2 of the present invention.

[0055] Example 3

[0056] The difference from Example 1 is that the catalyst raw material ratio is adjusted to a mixture of 0.2 g strontium acetate, 10 mmol copper acetate monohydrate, 5 mmol zinc acetate dihydrate, 5 mmol zirconium acetate and 80 mmol anhydrous oxalic acid.

[0057] The prepared alkaline earth metal-modified copper-based catalyst was tested for carbon dioxide hydrogenation performance:

[0058] 2g of the prepared alkaline earth metal-modified copper-based catalyst was loaded into a fixed bed and fed with a mixture of carbon dioxide and hydrogen. The mixture contained 4% by volume of argon as an internal standard for calculating conversion and selectivity. The volume ratio of carbon dioxide to hydrogen in the mixture was 1:3. The reaction was carried out continuously at 160°C, 50 bar, and 40 mL / min. The reaction exhaust passed through a fully insulated needle valve and heated pipe before entering a gas chromatograph for online analysis. After 5 hours of reaction, the carbon dioxide conversion reached 5.9%, while the methanol selectivity reached 92%.

[0059] Figure 5 3 is the XRD pattern of the copper-based catalyst according to Example 3 of the present invention.

[0060] Figure 6 Graph showing the catalytic performance of the copper-based catalyst according to Example 3 of the present invention.

[0061] Comparative Example 1

[0062] Preparation of copper-based catalyst without alkaline earth metal modification, the preparation method is as follows:

[0063] First, 10 mmol of copper acetate monohydrate, 4 mmol of zinc acetate dihydrate, 4 mmol of zirconium acetate and 80 mmol of anhydrous oxalic acid were mixed at room temperature, and then the mixture was fully ground and mixed at room temperature. Then, the mixture was heated to 120°C in an oven at a heating rate of 10°C / min, kept warm and dried for 12 hours, and the obtained product was further heated to 400°C in a muffle furnace at a heating rate of 5°C / min and maintained for 3 hours. After naturally cooling to room temperature, the product was obtained.

[0064] 2g of the prepared copper-based catalyst, free of alkaline earth metal modification, was loaded into a fixed bed and fed with a mixture of carbon dioxide and hydrogen. The mixture contained 4% by volume of argon as an internal standard for calculating conversion and selectivity. The volume ratio of carbon dioxide to hydrogen in the mixture was 1:3. The reaction was carried out continuously at 160°C, 50 bar, and 40 mL / min. The exhaust gas passed through a fully insulated needle valve and heated pipe before entering a gas chromatograph for online analysis. After 5 hours of reaction, the carbon dioxide conversion reached 4.5%, while the methanol selectivity reached 85%.

[0065] Figure 7 1 is the XRD pattern of the copper-based catalyst according to Comparative Example 1 of the present invention.

[0066] Figure 8Graph showing the catalytic performance of the copper-based catalyst according to Comparative Example 1 of the present invention.

[0067] Comparative Example 2

[0068] The conventional co-precipitated CuZnZr catalyst was prepared as follows:

[0069] First, 10 mmol of copper acetate monohydrate, 4 mmol of zinc acetate dihydrate, and 4 mmol of zirconium acetate were dissolved in 50 mL of deionized water. 80 mmol of anhydrous oxalic acid was dissolved in 50 mL of deionized water. Both solutions were then added dropwise to 50 mL of deionized water at 65°C, maintaining a pH of 7. The resulting suspension was then aged for 2 hours, filtered, and rinsed with deionized water. The product was dried in a 110°C oven for 12 hours and then calcined in a muffle furnace at 350°C for 4 hours at a heating rate of 5°C / min. The product was then naturally cooled to obtain the product.

[0070] 2g of the prepared co-precipitated CuZnZr catalyst was loaded into a fixed bed and fed with a mixture of carbon dioxide and hydrogen. Argon (4% by volume) was used as an internal standard for calculating conversion and selectivity. The volume ratio of carbon dioxide to hydrogen in the mixture was 1:3. The reaction was carried out continuously at 160°C, 50 bar, and 40 mL / min. The exhaust gas passed through a fully insulated needle valve and heated pipe before entering a gas chromatograph for online analysis. After 5 hours of reaction, the carbon dioxide conversion reached 3%, while the methanol selectivity reached 85%.

[0071] Figure 9 2 is the XRD pattern of the copper-based catalyst according to Comparative Example 2 of the present invention.

[0072] Figure 10 Graph showing the catalytic performance of the copper-based catalyst according to Comparative Example 2 of the present invention.

[0073] The catalyst provided by the above embodiment of the present invention is applied to the production of methanol by hydrogenation of carbon dioxide, has excellent performance, good catalytic activity, high selectivity for the target product, and has prospects for industrial application.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An alkaline earth metal-modified copper-based catalyst, characterized in that: The raw materials for preparing the copper-based catalyst include strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate, and anhydrous oxalic acid in a ratio of (0.1-0.2) g: (5-15) mmol: (2-5) mmol: (2-5) mmol: (40-100) mmol.

2. A method for preparing the alkaline earth metal-modified copper-based catalyst according to claim 1, characterized in that: The following steps are involved: Thoroughly grinding and mixing strontium acetate, copper acetate monohydrate, zinc acetate dihydrate, zirconium acetate, and anhydrous oxalic acid at room temperature, uniformly heating to the first temperature, and then maintaining the temperature for a period of time to obtain a second mixture; uniformly heating the second mixture to a second temperature and keeping the temperature for a period of time, and then naturally cooling the mixture to obtain an alkaline earth metal-modified copper-based catalyst; Wherein, the first temperature is 100-140°C, and the second temperature is 350-450°C.

3. The method for preparing the alkaline earth metal-modified copper-based catalyst according to claim 2, wherein: The heating rate for uniform heating to the first temperature is 5°C / min~15°C / min, and the heating rate for uniform heating to the second temperature is 5°C / min~15°C / min.

4. The method for preparing the alkaline earth metal-modified copper-based catalyst according to claim 3, wherein: The holding time for heating to the first temperature is 10 hours to 14 hours, and the holding time for heating to the second temperature is 2 hours to 4 hours.

5. Use of the alkaline earth metal-modified copper-based catalyst according to claim 1, characterized in that: The copper-based catalyst is used in the CO2 hydrogenation reaction to produce methanol.

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