Method for preparing methanol through CO2 hydrogenation by taking isopropanol as hydrogen source

Abstract

The invention discloses a method for preparing methanol through CO2 hydrogenation by taking isopropanol as a hydrogen source, which comprises the following steps: adding a catalyst and isopropanol into a reaction kettle, filling CO2 until the pressure is 0.1-3 MPa after inert gas replacement, and reacting for 1-7 hours at the temperature of 180-300 DEG C while stirring to obtain a product methanol, wherein the catalyst is a supported metal catalyst and comprises an active metal and a carrier; and the active metal is any one or an alloy form of Pt, Pd, Ru and Rh. According to the method, isopropanol is taken as a hydrogen source, and CO2 is subjected to hydrogenation conversion into methanol by adopting a supported noble metal catalyst; hydrogen is replaced with isopropanol, potential safety hazards caused by hydrogen can be solved from the source, meanwhile, reaction conditions are mild, the catalyst preparation process is simple, and the method has the advantages of being good in safety and easy to operate.

Description

Technical Field

[0001] The present invention relates to a CO 2 Method for preparing methanol by hydrogenation, especially a method for preparing methanol by hydrogenation using isopropanol as hydrogen source 2 A method for preparing methanol by hydrogenation. Background Art

[0002] The extensive use of fossil energy has led to CO 2 Emissions continue to increase, and the greenhouse effect and environmental degradation problems are exacerbated. Methanol is a clean, high-energy-density fuel with an energy density of 15.6 MJ / L. It has the advantages of being easy to store, non-toxic, and highly compatible with internal combustion engines. At the same time, it is widely used as a chemical raw material in the production of fine chemicals. 2 Using catalytic technology to convert CO into methanol is an effective means to reduce carbon emissions and achieve sustainable growth in green energy supply. 2 The technology of preparing methanol by hydrogenation has great application prospects.

[0003] However, CO 2 The conversion to methanol needs to be carried out in a hydrogen atmosphere, but hydrogen has a low density and is flammable and explosive, which poses a huge safety hazard during storage and transportation. Isopropyl alcohol, as a hydrogen source, is cheap, safe and non-toxic, and can solve the safety hazards caused by direct use of hydrogen from the source. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a safe CO 2 A method for preparing methanol by hydrogenation.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention comprises the following steps: adding a catalyst and isopropanol into a reaction kettle, replacing the inert gas with CO 2 The pressure is raised to 1-3 MPa, and the reaction is carried out at 180-300°C with stirring for 1-7 hours to obtain the product methanol; Wherein, the catalyst is a supported metal catalyst, which comprises an active metal and a carrier; the active metal is any one of Pt, Pd, Ru and Rh or an alloy thereof.

[0006] Furthermore, the active metal loading in the supported metal catalyst is 1 to 5 wt %.

[0007] Furthermore, the amount of isopropanol used is 10-30 ml; the amount of catalyst added is 0.05-0.3 g.

[0008] Furthermore, the carrier is CeO 2 、SiO 2 、Al2 O 3 and TiO 2 Any one of .

[0009] Furthermore, the supported metal catalyst is prepared by an equal volume impregnation method.

[0010] The beneficial effects of the above technical solution are as follows: the present invention uses isopropanol as a hydrogen source and adopts a supported precious metal catalyst to hydrogenate CO2 into methanol; using isopropanol instead of hydrogen can solve the safety hazards caused by the use of hydrogen from the source, and at the same time, the reaction conditions are mild, the catalyst preparation process is simple, and it has the characteristics of good safety and easy operation. DETAILED DESCRIPTION

[0011] The present invention is further described in detail below in conjunction with specific implementation modes.

[0012] The isopropanol is used as the hydrogen source for CO 2 The method for preparing methanol by hydrogenation comprises the following steps: adding a catalyst and isopropanol into a reaction kettle, replacing the inert gas with CO 2 The pressure is 1-3 MPa, nitrogen is preferably used as the inert gas, and the reaction is carried out at 180-300° C. with stirring for 1-7 hours to obtain crude methanol; the crude methanol is centrifuged, and the supernatant is filtered through a membrane to obtain refined methanol; the amount of isopropanol used is 10-30 ml; the amount of catalyst added is 0.05-0.3 g.

[0013] The catalyst is a supported metal catalyst, which comprises an active metal and a carrier; the active metal is any one of Pt, Pd, Ru and Rh or an alloy thereof, and the active metal loading is 1 to 5 wt%; the carrier is CeO 2 、SiO 2 、Al 2 O 3 and TiO 2 Any one of .

[0014] The supported metal catalyst is prepared by an equal volume impregnation method, and the preparation process is as follows: an active metal precursor aqueous solution and a carrier are impregnated in equal volumes according to a required ratio, and allowed to stand for 12 to 24 hours; then dried at 110 to 120° C. for 10 to 12 hours; then calcined in a muffle furnace at a calcination heating rate of 5 to 10° C. / min, calcined at 500 to 550° C. for 3 to 5 hours, taken out and allowed to stand and cool; finally, reduced at a heating rate of 5 to 10° C. / min in an atmosphere of hydrogen at 50 to 100 mL / min and nitrogen at 50 to 100 mL / min, and reduced at 300° C. for 1 to 2 hours; the active metal component precursor is a hydrochloride or nitrate of the active metal.

[0015] 5%Pt / CeO 2 Take the isovolumetric impregnation method as an example to illustrate the specific steps for preparing supported metal catalysts: (1) Measurement of carrier CeO 2 Saturated water absorption: Accurately weigh 1g of CeO 2 On the watch glass, add pure water drop by drop until the carrier is completely soaked and slightly flowing. The volume of pure water used is recorded as the saturated water absorption of the carrier.

[0016] (2) Preparation of supported metal catalyst by impregnation method: Accurately weigh CeO 2 1 g of carrier was placed in a crucible, and Pt(NO 3 ) 2 0.28g of the solution was added with pure water until the saturated water absorption of the carrier measured in step (1) was reached, and the mixture was uniformly mixed to form a platinum solution. The platinum solution was added dropwise onto the carrier until the carrier was completely soaked and slightly flowing; after standing for 12 hours, it was dried in a drying oven at 110°C for 12 hours; finally, the catalyst was calcined in a muffle furnace at 500°C for 3 hours, with a heating rate of 10°C / min.

[0017] (3) Reducing the catalyst: Before use, the catalyst was placed in a tubular resistance furnace for reduction. In a mixed atmosphere of hydrogen 80 mL / min and nitrogen 80 mL / min, the temperature was maintained at 300 °C for 2 h with a heating rate of 5 °C / min. The final theoretical loading of the catalyst was 5% for metal Pt.

[0018] Example 1: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0019] 0.2 g 5% Pt / CeO 2 Catalyst, 10 ml of isopropanol was added to the reaction kettle, and the reaction kettle was sealed and N 2 Replace the air in the kettle 6 times; fill with CO 2 To 1.5Mpa, set the reaction temperature to 200℃ and start heating, set the stirring speed to 700rpm, and cool to room temperature in a cold water bath after 7h of reaction. Centrifuge the reaction solution in a centrifuge tube at a speed of 4000r / min for 5min, and then further filter the supernatant with a 0.22μm pore size organic filter membrane. Finally, gas chromatography was used for qualitative and quantitative analysis to determine that the methanol yield was 10.4% and the other product was acetone.

[0020] Example 2: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0021] The other steps are the same as in Example 1, except that the catalyst added is 5% Pt / γ-Al2 O 3 , the methanol yield was 5.5%.

[0022] Example 3: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0023] The other steps are the same as in Example 1, except that the catalyst added is 5% Pt / TiO 2 , the methanol yield was 4.3%.

[0024] Example 4: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0025] The other steps are the same as in Example 1, except that the catalyst added is 5% Pd / CeO 2 , the methanol yield was 3.6%.

[0026] Example 5: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0027] The other steps are the same as in Example 1, except that the catalyst added is 5% Ru / CeO 2 , the methanol yield was 6.7%.

[0028] Example 6: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0029] The other steps are the same as in Example 1, except that the catalyst added is 5% Rh / CeO 2 , the methanol yield was 6.4%.

[0030] Example 7: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0031] The other steps are the same as in Example 1, except that the catalyst added is 1% Pt / CeO 2 , the methanol yield was 2.4%.

[0032] Example 8: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0033] The other steps were the same as in Example 1, except that the reaction time was 4 h and the methanol yield was 3.4%.

[0034] Example 9: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0035] The other steps were the same as in Example 1, except that the reaction time was 6 h and the methanol yield was 8.5%.

[0036] Example 10: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0037] The other steps were the same as in Example 1, except that the amount of isopropanol added was 20 ml, and the methanol yield was 10.3%.

[0038] Example 11: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0039] The other steps were the same as in Example 1, except that the amount of isopropanol added was 30 ml and the methanol yield was 10.6%.

[0040] Example 12: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0041] The other steps were the same as in Example 1, except that the amount of catalyst added was 0.05 g and the methanol yield was 1.96%.

[0042] Example 13: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0043] The other steps were the same as in Example 1, except that the amount of catalyst added was 0.1 g and the methanol yield was 4.6%.

[0044] Example 14: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0045] The other steps were the same as in Example 1, except that the amount of catalyst added was 0.3 g and the methanol yield was 15.6%.

[0046] Example 15: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0047] The other steps were the same as those in Example 13, except that the reaction temperature was 250° C. and the methanol yield was 16.6%.

[0048] Example 16: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0049] The other steps were the same as those in Example 13, except that the reaction temperature was 300° C. and the methanol yield was 19.9%.

[0050] Example 17: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0051] The other steps were the same as in Example 16, except that CO 2 The pressure was 1MPa and the methanol yield was 15.9%.

[0052] Example 18: CO with isopropanol as hydrogen source 2 The method for preparing methanol by hydrogenation is specifically described as follows.

[0053] The other steps were the same as in Example 16, except that CO 2 The pressure was 3MPa and the methanol yield was 21.4%.

Claims

1. A method for preparing methanol by hydrogenating CO2 using isopropanol as a hydrogen source, characterized in that: The method comprises the following steps: adding a catalyst and isopropanol into a reaction kettle, replacing the inert gas with CO2 to a pressure of 1 to 3 MPa, reacting at 180 to 300° C. with stirring for 1 to 7 hours to obtain a product, methanol; Wherein, the catalyst is a supported metal catalyst, which comprises an active metal and a carrier; the active metal is any one of Pt, Pd, Ru and Rh or an alloy thereof.

2. The method for preparing methanol by hydrogenating CO2 using isopropanol as a hydrogen source according to claim 1, characterized in that: The active metal loading in the supported metal catalyst is 1 to 5 wt %.

3. The method for preparing methanol by hydrogenating CO2 using isopropanol as a hydrogen source according to claim 1, characterized in that: The amount of isopropanol used is 10-30 ml; the amount of catalyst added is 0.05-0.3 g.

4. The method for preparing methanol by hydrogenating CO2 using isopropanol as a hydrogen source according to claim 1, characterized in that: The carrier is any one of CeO2, SiO2, Al2O3 and TiO2.

5. A method for preparing methanol by hydrogenating CO2 using isopropanol as a hydrogen source according to any one of claims 1 to 4, characterized in that: The supported metal catalyst is prepared by an equal volume impregnation method.