A catalyst for the synthesis of methanol and a process for its preparation

Abstract

The application discloses a catalyst for synthesizing methanol, and a preparation method of the catalyst, which comprises the following steps: (1) adding gamma-Al2O3 powder into a salt solution corresponding to an alkaline earth metal, then adding triethanolamine, uniformly mixing, and placing in a muffle furnace for calcination to obtain a pretreated gamma-Al2O3 carrier; (2) firstly, immersing the pretreated gamma-Al2O3 carrier in a calcium nitrate solution, and drying the catalyst precursor after immersion; (3) dissolving copper nitrate, cesium nitrate and ammonium metavanadate in deionized water to obtain a mixed solution, immersing the catalyst precursor obtained in the step (2) in the mixed solution, slowly adding an acid solution to control pH after immersion for a period of time, until precipitation is generated, and then filtering, washing, drying and calcining to obtain the catalyst. The catalyst prepared by the method has high methanol selectivity and can maintain high stability in the case of being exposed to air for a long time.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology for methanol preparation processes, specifically to a catalyst for synthesizing methanol and its preparation method. Background Technology

[0002] Fossil fuels are non-renewable, and their excessive combustion causes excessive emissions of greenhouse gases, especially carbon dioxide, posing a significant threat to ecosystems. Therefore, recycling and utilizing carbon dioxide in an environmentally friendly manner not only alleviates the environmental pressure caused by the greenhouse effect but also provides a new approach to energy utilization. Methanol is an important chemical raw material, commonly used in the manufacture of olefins, biodiesel, and fuel additives.

[0003] Currently, copper-based catalysts are commonly used in the catalytic reduction reaction of methanol production via carbon dioxide hydrogenation. Patent CN202211556947.1 discloses a catalyst for methanol production via carbon dioxide hydrogenation, its preparation method, and its application. The catalyst uses SPP molecular sieves as a support and CuO and ZnO as active components, with CuO accounting for 9.6-41.5 wt.% and ZnO accounting for 4.5-18.0 wt.%. The method involves impregnating the SPP molecular sieves in a mixed aqueous solution of Cu and Zn salts, followed by drying and calcination to obtain the catalyst. This patented catalyst exhibits highly dispersed CuO and ZnO particles, and its preparation process is simple. However, the catalytic activity of this catalyst needs improvement; the best carbon dioxide conversion data disclosed in this patent shows a conversion rate of less than 35%.

[0004] Patent CN201610826535.3 discloses a high-temperature resistant catalyst for the hydrogenation of carbon dioxide to methanol, its preparation, and its application. The catalyst is composed of two metal oxides, denoted as AOxBOy, where A is Zn, Cd, or In, and B is Zr or Cr. The preparation method involves co-precipitation of the metal salt with a precipitant. Compared to the currently mainstream CuZnO-based catalysts, the metal oxide catalyst of this invention can effectively improve methanol selectivity. Under conditions of 5 MPa, 330℃, and 24000 mL / (g / h), the methanol selectivity on the ZnO and ZrO2 catalysts can reach 80%. However, this catalyst contains In, a metal that can cause pneumonia or even lung cancer if inhaled, posing a certain risk during catalyst preparation.

[0005] Currently available catalysts, and their application in the methanol production process via carbon dioxide hydrogenation, both of which require high temperatures and pressures for catalytic reaction, resulting in high energy consumption, increased investment costs, and environmental disadvantages. Furthermore, the activity of most catalysts is affected by their storage environment; prolonged exposure to air can lead to catalyst deactivation. Therefore, developing a more stable catalyst is also crucial. Summary of the Invention

[0006] To address the problems of harsh reaction conditions and poor catalyst stability in current catalytic reactions for the hydrogenation of carbon dioxide to methanol, this paper provides a catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A catalyst for synthesizing methanol, the preparation method of the catalyst comprising the following steps:

[0009] (1) Add γ-Al2O3 powder to the salt solution corresponding to the alkaline earth metal, then add triethanolamine, mix well and calcine in a muffle furnace to obtain the pretreated γ-Al2O3 support.

[0010] (2) First, the pretreated γ-Al2O3 support was impregnated in calcium nitrate solution, and then dried to obtain the catalyst precursor.

[0011] (3) Dissolve copper nitrate, cesium nitrate and ammonium metavanadate in deionized water to obtain a mixed solution. Place the catalyst precursor obtained in step (2) into the mixed solution for immersion. After immersion for a period of time, slowly add acidic solution to control the pH until a precipitate is formed. Then filter, wash, dry and calcine to obtain the catalyst.

[0012] Furthermore, in step (1), the alkaline earth metal is magnesium, and the salt solution corresponding to the alkaline earth metal is a nitrate solution.

[0013] Furthermore, the magnesium nitrate constitutes 10%-35% of the mass of the γ-Al₂O₃ powder.

[0014] Furthermore, in step (1), the addition of triethanolamine controls the pH to be between 8 and 8.5, and the calcination conditions are calcination at 650°C for 5-7 hours.

[0015] Furthermore, in step (2), the soaking time is 4-6 hours and the soaking temperature is 30-40℃; the calcium nitrate solution concentration is 30-55 g / L.

[0016] Furthermore, the filter cake filtered in step (2) is washed with deionized water and dried in a vacuum drying oven at 120°C for 6-8 hours.

[0017] Furthermore, in step (3), the molar ratio of metallic copper, cesium and vanadium in copper nitrate, cesium nitrate and ammonium metavanadate is 10:1.5-5:1-3, and the temperature during the preparation of the mixed solution is 30-40℃.

[0018] Furthermore, in step (3), the immersion time is 5 to 10 hours, and the immersion is an equal volume immersion.

[0019] Furthermore, the acidic solution added in step (3) consists of methanol and formic acid in a volume ratio of 1:2. The temperature is maintained at 55-60°C during the addition process, and the pH is controlled at 7-8 during the addition process.

[0020] Furthermore, in step (3), the filtered cake is washed with deionized water and methanol solution, and the heating rate to 700℃ during the calcination process is 1.5℃ / min, and the calcination time is 6-9h.

[0021] The present invention has the following beneficial effects:

[0022] 1. The present invention provides a catalyst for the synthesis of methanol, which is prepared by treating alkaline earth metals and alumina to obtain a catalyst precursor. Through impregnation, the maximum amount of metal salts containing calcium, copper, cesium and vanadium are loaded onto the support. Compared with existing catalysts for the preparation of methanol, this catalyst can efficiently catalyze the conversion of carbon dioxide into methanol under mild conditions.

[0023] 2. The catalyst for methanol synthesis provided by this invention is treated with alkaline earth metals and triethanolamine during the preparation of the support, which enables the catalyst to withstand different environmental conditions and improves its stability.

[0024] 3. The catalyst for synthesizing propanol provided by the present invention has high catalytic activity due to the addition of vanadium oxide in the active component. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments.

[0026] Example 1

[0027] Catalyst preparation:

[0028] (1) Add γ-Al2O3 powder (purchased from Shandong Bairui Chemical Co., Ltd., 98%) to magnesium nitrate solution. The amount of magnesium nitrate weighed is 20% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90℃ for 5 hours. Then, place it in a calcining furnace and calcinate it at 650℃. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0029] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0030] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3:2, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was methanol and formic acid in a volume ratio of 1:2. The purity of methanol was 98% and the concentration of formic acid was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dry solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0031] Example 2

[0032] Catalyst preparation:

[0033] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0034] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0035] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3:2, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a 1:2 volume ratio. The methanol purity was 98% and the formic acid concentration was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0036] Example 3

[0037] Catalyst preparation:

[0038] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8.5. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0039] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0040] (3) Based on the molar ratio of copper, cesium and vanadium of 10:1:3, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a 1:2 volume ratio. The methanol purity was 98% and the formic acid concentration was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0041] Example 4

[0042] Catalyst preparation:

[0043] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0044] (2) Prepare a calcium nitrate solution with a concentration of 55 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0045] (3) Based on the molar ratio of copper, cesium and vanadium of 10:5:1, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a volume ratio of 1:2. The purity of methanol was 98% and the concentration of formic acid was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0046] Example 5

[0047] Catalyst preparation:

[0048] (1) Add γ-Al2O3 powder to deionized water, weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder, then add triethanolamine while stirring to control the pH of the solution system to 8, filter and place the filter cake in an oven to dry at 90℃ for 5h, then place it in a calcination furnace to calcinate at 650℃, and introduce steam into the calcination furnace during the calcination process for 6h. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0049] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0050] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3: / , a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a 1:2 volume ratio. The methanol purity was 98% and the formic acid concentration was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0051] Example 6

[0052] Catalyst preparation:

[0053] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0054] (2) Prepare a calcium nitrate solution with a concentration of 20 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0055] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3:2, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a 1:2 volume ratio. The methanol purity was 98% and the formic acid concentration was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0056] Example 7

[0057] Catalyst preparation:

[0058] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0059] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0060] (3) Based on the molar ratio of copper, cesium and vanadium of 5∶6∶0.5, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a volume ratio of 1:2. The purity of methanol was 98% and the concentration of formic acid was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0061] Example 8

[0062] Catalyst preparation:

[0063] (1) Add γ-Al2O3 powder to magnesium nitrate solution, and weigh magnesium nitrate to be 30% of the mass of γ-Al2O3 powder. Then, while stirring, add triethanolamine to control the pH of the solution system to 8. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then, place it in a calcining furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcining furnace for treatment. The treatment time is 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0064] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0065] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3:2, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was 5% methanol and formic acid in a 1:2 volume ratio. The methanol purity was 98% and the formic acid concentration was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 6. Then the filter cake was dried, and the resulting dried solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0066] Example 9

[0067] Catalyst preparation:

[0068] (1) Add γ-Al2O3 powder to deionized water, and then add triethanolamine while stirring to control the pH of the solution system to 9. After filtration, place the filter cake in an oven and dry it at 90°C for 5 hours. Then place it in a calcination furnace and calcinate it at 650°C. During the calcination process, steam is introduced into the calcination furnace for treatment for 6 hours. After calcination, the pretreated γ-Al2O3 carrier is obtained.

[0069] (2) Prepare a calcium nitrate solution with a concentration of 45 g / L, and then immerse the pretreated γ-Al2O3 support in the calcium nitrate solution for 5 h. During the immersion process, maintain the temperature at 35 °C. After immersion, filter and wash, and then dry in a vacuum drying oven at 120 °C for 6-8 h.

[0070] (3) Based on the molar ratio of copper, cesium and vanadium of 10:3:2, a mixed solution of copper nitrate, cesium nitrate and ammonium metavanadate was prepared. The solvent was deionized water. During the preparation of the mixed solution, the system temperature was maintained at 30-40℃. The catalyst precursor was immersed in the mixed solution. After immersion for 7 hours, an acidic solution was slowly added dropwise. The acidic solution was methanol and formic acid in a volume ratio of 1:2. The purity of methanol was 98% and the concentration of formic acid was 1.5 mol / L. During the dropwise addition, the temperature was maintained at 55-60℃, and nitrogen gas was purged at the same time until a precipitate was formed. After filtration, the filter cake was washed with deionized water and methanol solution until the pH of the washing liquid was 7-8. Then the filter cake was dried, and the resulting dry solid was calcined at 700℃ for 7 hours. The heating rate to 700℃ during the calcination process was 1.5℃ / min. The catalyst was then obtained.

[0071] Catalyst activity determination method

[0072] The reaction was carried out in a fixed-bed tubular reactor with an inner diameter of 25 mm and a length of 1500 mm. The catalyst was packed in the isothermal zone of the reactor with a loading volume of 35 ml. The reaction pressure was 1.2 MPa, the reaction temperature was 180 °C, and the gas hourly space velocity (GHSV) was 100 h⁻¹. -1 The reaction feedstock contained 15% carbon dioxide by volume, 8% hydrogen by volume, and the remainder nitrogen. The methanol selectivity was analyzed after the reaction was completed.

[0073] The methanol selectivity of the catalysts prepared in Examples 1-8 was determined according to the above-described activity determination method. The results of the methanol selectivity test are summarized in Table 1 below.

[0074] Table 1

[0075]

[0076] Based on the methanol selectivity results of the catalysts prepared in Table 1 above, changing the proportion of active metal or not adding active components containing vanadium metal will reduce the methanol selectivity.

[0077] Similarly, in Example 8, the pH of the final wash after metal loading onto the carrier also affects the selectivity of methanol.

[0078] In the catalyst support preparation process, as in Example 9, no alkaline earth metals were added, and the pH was adjusted to 9 with triethanolamine. The final catalyst was exposed to air for 30 days, just like the catalyst prepared in Example 1. After 30 days, the methanol selectivity of the catalyst was tested. It was found that the methanol selectivity of the catalyst prepared in Example 1 was 90.5%, while the methanol selectivity of the catalyst prepared with the support without alkaline earth metal treatment was 75.9%.

[0079] As can be seen from the above, the stability of the catalyst will be significantly reduced when the support has not been treated with alkaline earth metals and the pH range is changed by triethanolamine.

Claims

1. A catalyst for synthesizing methanol, characterized in that, The preparation method of the catalyst includes the following steps: (1) Add γ-Al2O3 powder to the salt solution corresponding to the alkaline earth metal, then add triethanolamine, mix well and calcine in a muffle furnace to obtain the pretreated γ-Al2O3 support. (2) First, the pretreated γ-Al2O3 support is immersed in calcium nitrate solution and then dried to obtain the catalyst precursor; (3) Dissolve copper nitrate, cesium nitrate and ammonium metavanadate in deionized water to obtain a mixed solution. Place the catalyst precursor obtained in step (2) into the mixed solution for immersion. After immersion for a period of time, slowly add acidic solution to control the pH until a precipitate is formed. Then filter, wash, dry and calcine to obtain the catalyst. In step (1), the alkaline earth metal is magnesium, the corresponding salt solution for the alkaline earth metal is a nitrate solution, and the magnesium nitrate is 10%-35% of the mass of the γ-Al2O3 powder; In step (3), the molar ratio of metallic copper, cesium and vanadium in copper nitrate, cesium nitrate and ammonium metavanadate is 10:1.5-5:1-3, and the temperature during the preparation of the mixed solution is 30-40℃. In step (3), the acidic solution added consists of methanol and formic acid in a 1:2 volume ratio. The temperature is maintained at 55-60℃ during the addition process, and the pH is controlled at 7-8.

2. The catalyst according to claim 1, characterized in that, In step (1), the addition of triethanolamine keeps the pH between 8 and 8.5, and the calcination conditions are calcination at 650°C for 5-7 hours.

3. The catalyst according to claim 1, characterized in that, In step (2), the soaking time is 4-6 hours and the soaking temperature is 30-40℃; the concentration of the calcium nitrate solution is 30-55 g / L.

4. The catalyst according to claim 1, characterized in that, The filter cake after filtration in step (2) is washed with deionized water and dried in a vacuum drying oven at 120℃ for 6-8 hours.

5. The catalyst according to claim 1, characterized in that, In step (3), the soaking time is 5 to 10 hours, and the soaking is an equal volume soaking.

6. The catalyst according to claim 1, characterized in that, The filter cake after filtration in step (3) is washed with deionized water and methanol solution. During the calcination process, the heating rate to 700℃ is 1.5℃ / min, and the calcination time is 6-9h.

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