Liquid sunlight methanol synthesis catalyst, its preparation method and application

Abstract

The application relates to a liquid sunlight methanol synthesis catalyst and a preparation method and application thereof. The catalyst comprises a metal oxide solid solution; the metal oxide comprises cadmium oxide, zinc oxide and zirconium oxide; the ratio of the molar amount of cadmium elements to the total molar amount of zinc elements and zirconium elements in the catalyst is 1:100-10:100; the ratio of the molar amount of zinc elements to the molar amount of zirconium elements in the catalyst is 1:9-9:1; the catalyst is mainly used for liquid sunlight methanol synthesis. After the zinc-zirconium solid solution catalyst is doped with a third component Cd, the carbon dioxide conversion rate and the methanol space-time yield of the catalyst are improved compared with those of the original zinc-zirconium solid solution catalyst.

Description

Technical Field

[0001] This application belongs to the field of catalysts, specifically relating to a liquid solar-powered methanol synthesis catalyst, its preparation method, and its application. Background Technology

[0002] my country's total carbon dioxide emissions reach approximately 10 billion tons per year, accounting for 32% of global carbon dioxide emissions. The carbon dioxide emissions per 10,000 yuan of GDP are 1.02 tons, nearly 80% higher than the global average. Therefore, my country is heavily reliant on a high-carbon development path, and in order to achieve its carbon peaking and carbon neutrality goals, it is urgent to explore effective carbon dioxide emission reduction pathways.

[0003] Methanol is one of the most important industrial raw materials and also a good fuel. The synthesis of methanol from CO2 via hydrogenation is the most efficient strategy for achieving this route. Copper-based catalysts have been extensively studied for the hydrogenation of CO2 to methanol. However, copper-based catalysts exhibit low selectivity and poor stability due to the competitive reverse water-gas shift reaction and the sintering of the active phase. Therefore, there is an urgent need to explore efficient catalysts for the hydrogenation of CO2 to methanol.

[0004] Although zinc-zirconium solid solution catalysts have shown excellent catalytic performance, their activity needs to be further improved. Summary of the Invention

[0005] This application incorporates a third component into a zinc-zirconium oxide solid solution catalyst, which significantly promotes the hydrogenation of carbon dioxide to methanol. The doping of the third component, Cd, maintains high selectivity for methanol while improving carbon dioxide conversion, thereby increasing the space-time yield of methanol. Furthermore, this CdZnZr catalyst exhibits good heat resistance, anti-sintering properties, and high stability.

[0006] According to one aspect of this application, a liquid solar-powered methanol synthesis catalyst is provided for the hydrogenation of carbon dioxide to methanol;

[0007] The catalyst comprises a metal oxide solid solution;

[0008] The metal oxides include cadmium oxide, zinc oxide, and zirconium oxide;

[0009] The molar ratio of zinc to zirconium in the catalyst is 1:9 to 9:1.

[0010] The molar ratio of cadmium to the total molar ratio of zinc and zirconium in the catalyst is 1:100 to 10:100.

[0011] The catalyst has a specific surface area of ​​40–50 m². 2 / g; pore volume is 0.05~0.10cm³ 3 / g; average pore size is 3-5nm;

[0012] According to another aspect of this application, a method for preparing the above-mentioned catalyst for the hydrogenation of carbon dioxide to methanol is provided, comprising at least a precipitation method or an impregnation method.

[0013] The precipitation method includes at least the following steps:

[0014] An aqueous solution containing cadmium, zinc and zirconium sources is mixed with an aqueous solution containing a precipitant to obtain mixed solution I, reaction I, calcination I, to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0015] The impregnation method includes at least the following steps:

[0016] (1) Mix the aqueous solution of the raw materials containing zinc source and zirconium source with the aqueous solution containing precipitant to obtain mixed solution II, reaction II, calcination II, to obtain zinc zirconium solid solution;

[0017] (2) The raw material containing cadmium source is mixed with the zinc zirconium solid solution obtained in (1) and water to obtain mixed solution III, reaction III, calcination III, to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0018] The cadmium source is selected from at least one of cadmium nitrate, acetate, halide or sulfate.

[0019] The zinc source is selected from at least one of zinc nitrates, acetates, halides, or sulfates.

[0020] The zirconium source is selected from at least one of zirconium nitrate, acetate, halide or sulfate;

[0021] The precipitant is selected from at least one of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, or potassium hydroxide.

[0022] In the precipitation method

[0023] The total molar concentration of cadmium, zinc and zirconium in the mixed solution I is 0.4 to 0.6 mol / L; the molar ratio of zinc to zirconium is 1:9 to 9:1; and the molar ratio of cadmium to the total molar ratio of zinc and zirconium is 1:100 to 10:100.

[0024] The molar concentration of the precipitant in the mixed solution I is 0.05–1 mol / L;

[0025] The total molar ratio of cadmium, zinc, and zirconium in the mixed solution I to the molar ratio of the precipitant is 1:1.2 to 1:1.5.

[0026] The temperature of reaction I is 50–80°C;

[0027] The reaction time for reaction I is 0.2–1 hour;

[0028] The temperature of the calcination I is 450–500°C;

[0029] The roasting time for step I is 2–6 hours;

[0030] Before roasting I, the process also involves drying I, with the temperature of drying I being 40–120°C and the drying time being 6–12 hours.

[0031] In the impregnation method

[0032] In (1), the pH value of the mixed solution II is 6 to 10;

[0033] The total molar concentration of zinc and zirconium in the mixed solution II is 0.01–2 mol / L; the molar ratio of zinc to zirconium is 1:9 to 9:1.

[0034] The ratio of the total molar amount of zinc and zirconium in the mixed solution II to the molar concentration of the precipitant is 1:1.2 to 1:1.5;

[0035] The temperature of reaction II is 20–90°C;

[0036] The reaction time for reaction II is 0.2–1 h;

[0037] The temperature of the second calcination is 400–800°C;

[0038] The roasting time for II is 2–6 hours;

[0039] Before roasting II, the process also includes drying II; the temperature of drying II is 60–130°C; and the drying time is 6–12 hours.

[0040] The molar ratio of cadmium to the total molar ratio of zinc and zirconium in the mixed solution III is 1:100 to 10:100.

[0041] The amount of zinc-zirconium solid solution obtained in (1) is 1-5g.

[0042] Reaction III is a stirred evaporation process;

[0043] The temperature of reaction III is 100–130°C;

[0044] The reaction time for reaction III is 2–6 hours;

[0045] The temperature of calcination III is 400–800°C;

[0046] The roasting time for III is 2–6 hours;

[0047] The mixed solution III is subjected to ultrasound; the ultrasound time is 10 to 30 minutes.

[0048] According to another aspect of this application, a method for hydrogenating carbon dioxide to methanol is provided, comprising at least the following steps:

[0049] A raw material containing carbon dioxide and hydrogen is brought into contact with a catalyst, and reaction IV is carried out to obtain a product containing methanol.

[0050] The catalyst is selected from the above-described catalysts for the hydrogenation of carbon dioxide to methanol or the catalysts for the hydrogenation of carbon dioxide to methanol prepared by the above-described preparation method.

[0051] The catalyst has undergone pretreatment;

[0052] The preprocessing procedure includes at least the following steps:

[0053] Treat in an activating atmosphere at a temperature of 200–400°C for 0.5–12 hours;

[0054] The activation atmosphere is selected from at least one of hydrogen, nitrogen, or argon.

[0055] The gas pressure of the raw material is 1-10 MPa;

[0056] The feed space velocity of the raw material is 3000-40000 h⁻¹. –1 ;

[0057] The molar ratio of hydrogen to carbon dioxide in the raw material is 1 to 8;

[0058] The temperature of reaction IV is 240–400°C;

[0059] The method is carried out in a fixed-bed reactor.

[0060] The beneficial effects of this application are as follows:

[0061] The catalyst described in this application can effectively improve the selectivity of methanol production from carbon dioxide hydrogenation, and its optimal operating temperature is 280–320℃ at 5 MPa, 300℃, for 24000 h⁻¹. –1 Under the same operating conditions, the catalyst described in this application can effectively improve CO2 conversion and methanol yield. It can achieve a single-pass carbon dioxide conversion of 7.3%, a methanol selectivity of over 84.9%, and a methanol space-time yield of 510 mg / (gh) under the same operating conditions. Attached Figure Description

[0062] Figure 1 The image shows the XRD pattern of the sample obtained in Example 1. Detailed Implementation

[0063] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0064] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0065] The detection method is as follows: The reaction tail gas is discharged to atmospheric pressure through a back pressure valve, and sampled through a 10-port gas chromatograph at 150℃. The sample is then analyzed online using a thermal conductivity detector (TCD) and a flame ionization detector (FID) of an Agilent GC-7890B gas chromatograph. The TCD column is a 3m long column coupled with a Propark Q 5A molecular sieve, using H2 as the carrier gas, operating at 85℃, and is used to separate and detect CO2, Ar, and CO. The FID column is a TG-BOND Q capillary column (Thermo Fisher Scientific), with dimensions of 30m × 0.32mm × 10μm, using N2 as the carrier gas, and is used for the separation and detection of CO2, Ar, and CO.

[0066] Low-carbon hydrocarbons and alcohols.

[0067] Calculation method:

[0068] The formula for calculating the CO2 conversion rate is as follows:

[0069]

[0070] The molecule represents the total amount of each product in the gaseous state after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3, and C4 products.

[0071] The denominator represents the total amount of carbon-containing substances in the gas after the reaction, including unreacted CO2 and the products CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3 and C4 compounds.

[0072] The formula for calculating methanol selectivity is:

[0073]

[0074] Where the molecule represents the amount of CH3OH product in the gas after the reaction.

[0075] The denominator represents the total amount of each product in the gaseous mixture after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3, and C4 products.

[0076] The formula for calculating CO selectivity is:

[0077]

[0078] Where the molecule represents the amount of CO product in the gas after the reaction.

[0079] The denominator represents the total amount of each product in the gaseous mixture after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3, and C4 products.

[0080] The formula for calculating methanol yield is:

[0081]

[0082] Where GHSV represents the mass hourly space velocity of the reaction, with units of mL / (g·h), V%(CO2) represents the volume fraction of CO2 in the reaction gas, and X CO2 S represents the CO2 conversion rate. CH3OH This represents the selectivity of methanol.

[0083] Example 1

[0084] 0.5 mmol Cd(NO3)2·9H2O, 4 mmol Zn(NO3)2·6H2O, and 16 mmol Zr(NO3)4·5H2O were weighed to prepare a 100 mL metal salt solution; 50 mmol Na2CO3 was weighed to prepare a 100 mL Na2CO3 aqueous solution and placed in a 500 mL three-necked beaker; the metal salt solution and the Na2CO3 aqueous solution were added dropwise to 100 mL of water at 70 °C; the stirring speed was 600 r / min, the precipitation rate was 3.3 mL / min, and the reaction was carried out at 70 °C for 2 h, followed by aging at stillness for 2 h, and then filtered. The filter cake was washed with 5 L of deionized water until no sodium ions were found in the filtrate; the filter cake was dried at 60 °C and calcined in air at 500 °C for 3 h to obtain a 2.5% CdZnZr-pre catalyst.

[0085] The 2.5% CdZnZr-pre catalyst was sequentially compressed, crushed, and screened to a mesh size of 40–80 under 30 MPa for evaluation. 0.1 g of the screened 2.5% CdZnZr-pre catalyst was weighed and loaded into a reaction tube with an inner diameter of 6 mm. Reduction was carried out at 320 °C for 2 h under normal pressure and pure H2 at a flow rate of 40 mL / min. Then, a feed gas with an n(H2):n(CO2) ratio of 3 was introduced, and the reaction was carried out at 5 MPa, 320 °C, and GHSV = 24000 h. –1 The catalyst was tested under the following conditions. The single-pass conversion rate of carbon dioxide reached 7.3%, the methanol selectivity exceeded 84.9%, and the methanol space-time yield reached 510 mg / (g·h). Detailed results of the catalyst evaluation are shown in Table 1.

[0086] The physical parameters of the sample are as follows:

[0087] sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Average pore size (nm) 2.5% CdZnZr-pre 44.23 0.068 3.82

[0088] Figure 1 The image shows the XRD pattern of the sample obtained in Example 1. The image indicates that the sample composition is 2.5% CdZnZr.

[0089] Example 2

[0090] Weigh 1.1 mmol Cd(NO3)2·9H2O, 4 mmol Zn(NO3)2·6H2O, and 16 mmol Zr(NO3)4·5H2O to prepare a 100 mL metal salt solution. The other steps are the same as in Example 1 to obtain a 5% CdZnZr-pre catalyst. The catalyst has a carbon dioxide conversion rate of 7.3% and a methanol selectivity of 84.5%.

[0091] Example 3

[0092] Weigh 1.6 mmol Cd(NO3)2·9H2O, 4 mmol Zn(NO3)2·6H2O, and 16 mmol Zr(NO3)4·5H2O to prepare a 100 mL aqueous solution. The other steps are the same as in Example 1 to obtain a 7.5% CdZnZr-pre catalyst. The catalyst has a carbon dioxide conversion rate of 5.9% and a methanol selectivity of 85.3%.

[0093] Example 4

[0094] Weigh 4 mmol Zn(NO3)2·6H2O and 16 mmol Zr(NO3)4·5H2O to prepare a 100 mL metal salt solution; weigh 50 mmol Na2CO3 to prepare a 100 mL Na2CO3 aqueous solution and place it in a 500 mL three-necked beaker; add the metal salt solution and the Na2CO3 aqueous solution dropwise to 100 mL of water at 70 °C; stir at 600 r / min, with a precipitation rate of 3.3 mL / min, react at 70 °C for 2 h, then let stand for 2 h for aging, filter, and wash with 5 L of deionized water until no sodium ions are present in the filtrate; dry the filter cake at 60 °C and calcine it in air at 500 °C for 3 h to obtain the catalyst oxidized precursor, i.e., the zinc-zirconium solid solution catalyst support.

[0095] 0.035 g of Cd(NO3)2·9H2O was dissolved in 20 mL of deionized water. 2.00 g of the above zinc-zirconium solid solution catalyst support was added to the Cd(NO3)2 aqueous solution and sonicated for 10–30 minutes. The resulting suspension was stirred and evaporated at 110 °C and calcined at 500 °C for 3 h to obtain a 2.5% CdZnZr-imp catalyst.

[0096] The 2.5% CdZnZr-imp catalyst was sequentially compressed, crushed, and screened to a mesh size of 40–80 under 30 MPa for evaluation. 0.1 g of the screened 2.5% CdZnZr-imp catalyst was weighed and loaded into a reaction tube with an inner diameter of 6 mm. Reduction was carried out at 320 °C for 2 h under normal pressure and pure H2 at a flow rate of 40 mL / min. Then, a feed gas with n(H2):n(CO2) = 3 was introduced, and the reaction was carried out at 5 MPa, 320 °C, and GHSV = 24000 h. –1 The reaction was carried out under the specified conditions. The catalyst achieved a carbon dioxide conversion rate of 6.9% and a methanol selectivity of 84%. Detailed results of the catalyst evaluation are shown in Table 1.

[0097] Example 5

[0098] Prepare a 100 mL metal salt solution by taking 4 mmol Zn(NO3)2·6H2O and 16 mmol Zr(NO3)4·5H2O; weigh 50 mmol Na2CO3 to prepare a 100 mL Na2CO3 aqueous solution and place it in a 500 mL three-necked beaker; add the metal salt solution and Na2CO3 aqueous solution dropwise to 100 mL of water at 70 °C; stir at 600 r / min, with a precipitation rate of 3.3 mL / min, react at 70 °C for 2 h, then let stand for 2 h and filter, wash with 5 L of deionized water until no sodium ions are present in the filtrate; dry the filter cake at 60 °C and calcine it in air at 500 °C for 3 h to obtain the catalyst oxidized precursor, thus obtaining the zinc-zirconium solid solution catalyst support.

[0099] 0.07 g of Cd(NO3)2·9H2O was dissolved in 20 mL of deionized water. 2.00 g of the above zinc-zirconium solid solution catalyst support was weighed and added to the Cd(NO3)2 aqueous solution. The mixture was sonicated for 10–30 minutes. The resulting suspension was evaporated by stirring at 110 °C and calcined at 500 °C for 3 h. The other steps were the same as in Example 4, yielding a 5% CdZnZr-imp catalyst. The catalyst had a carbon dioxide conversion rate of 6.8% and a methanol selectivity of 84.9%.

[0100] Example 6

[0101] Prepare a 100 mL metal salt solution by taking 4 mmol Zn(NO3)2·6H2O and 16 mmol Zr(NO3)4·5H2O; weigh 50 mmol Na2CO3 to prepare a 100 mL Na2CO3 aqueous solution and place it in a 500 mL three-necked beaker; add the metal salt solution and Na2CO3 aqueous solution dropwise to 100 mL of water at 70 °C; stir at 600 r / min, with a precipitation rate of 3.3 mL / min, react at 70 °C for 2 h, then let stand for 2 h for aging, filter, and wash with 5 L of deionized water until no sodium ions are present in the filtrate; dry the filter cake at 60 °C and calcine it in air at 500 °C for 3 h to obtain the catalyst oxidized precursor, thus obtaining the zinc-zirconium solid solution catalyst support.

[0102] 0.105 g of Cd(NO3)2·9H2O was weighed and dissolved in 20 mL of deionized water. 2.00 g of the above zinc-zirconium solid solution catalyst support was weighed and added to the Cd(NO3)2 aqueous solution. The mixture was sonicated for 10–30 minutes. The resulting suspension was evaporated by stirring at 110 °C and calcined at 500 °C for 3 h. Other steps were the same as in Example 4, yielding a 7.5% CdZnZr-imp catalyst. The catalyst had a carbon dioxide conversion rate of 6% and a methanol selectivity of 85.1%.

[0103] Comparative Example 1

[0104] Prepare a 100 mL metal salt solution by taking 4 mmol Zn(NO3)2·6H2O and 16 mmol Zr(NO3)4·5H2O; weigh 50 mmol Na2CO3 to prepare a 100 mL Na2CO3 aqueous solution and place it in a 500 mL three-necked beaker; add the metal salt solution and Na2CO3 aqueous solution dropwise to 100 mL of water at 70 °C; stir at 600 r / min, with a precipitation rate of 3.3 mL / min, react at 70 °C for 2 h, then let stand for 2 h and filter, wash with 5 L of deionized water until no sodium ions are present in the filtrate; dry the filter cake at 60 °C and calcine it in air at 500 °C for 3 h to obtain the catalyst oxidized precursor. The other steps are the same as in Example 4 to obtain a zinc-zirconium solid solution catalyst. The carbon dioxide conversion rate of this catalyst is 5.6%, and the methanol selectivity is 88%.

[0105] Table 1. Catalytic performance evaluation results of the examples and comparative examples.

[0106]

[0107] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A liquid solar-powered methanol synthesis catalyst, characterized in that, Used for hydrogenating carbon dioxide to methanol; The catalyst comprises a metal oxide solid solution; The metal oxide solid solution is a cadmium-doped zinc zirconium oxide solid solution; The molar ratio of zinc to zirconium in the catalyst is 1:4; The molar ratio of cadmium to the total molar ratio of zinc and zirconium in the catalyst is 2.5:

100. The catalyst has a specific surface area of ​​44.23 m². 2 / g; pore volume is 0.068cm³ 3 / g; average pore size is 3.82nm.

2. A method for preparing the liquid solar-powered methanol synthesis catalyst according to claim 1, characterized in that... Includes the following steps: 0.5 mmol Cd(NO3)2·9H2O, 4 mmol Zn(NO3)2·6H2O, and 16 mmol Zr(NO3)4·5H2O were weighed to prepare a 100 mL metal salt solution; 50 mmol Na2CO3 was weighed to prepare a 100 mL Na2CO3 aqueous solution; the metal salt solution and the Na2CO3 aqueous solution were added dropwise to 100 mL of water at 70 °C; after reacting at 70 °C for 2 h, the mixture was allowed to stand for 2 h for aging, washed with deionized water, dried at 60 °C, and calcined in air at 500 °C for 3 h to obtain the liquid solar methanol synthesis catalyst.

3. A method for hydrogenating carbon dioxide to methanol, characterized in that, At least the following steps are included: A raw material containing carbon dioxide and hydrogen reacts with a catalyst to produce a product containing methanol. The catalyst is the liquid sunlight methanol synthesis catalyst according to claim 1 or the liquid sunlight methanol synthesis catalyst prepared according to the method of claim 2.

4. The method according to claim 3, characterized in that, The catalyst has undergone pretreatment; The preprocessing procedure includes at least the following steps: Treat in a reducing atmosphere at a temperature of 200~400℃ for 0.5~12h; The reducing atmosphere is selected from at least one of hydrogen, nitrogen, or argon.

5. The method according to claim 3, characterized in that, The gas pressure of the raw material is 1~10MPa; The feed space velocity of the raw material is 3000-40000 h⁻¹. –1 ; The molar ratio of hydrogen to carbon dioxide in the raw material is 1 to 8; The reaction temperature is 240~400℃; The method is carried out in a fixed-bed reactor.

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