Catalyst with high specific surface area for preparing methanol from synthesis gas as well as preparation method and application of catalyst

Abstract

The invention provides a high-specific-surface-area catalyst for preparing methanol from synthesis gas as well as a preparation method and application of the catalyst. When the catalyst is applied to preparation of methanol from synthesis gas, the CO conversion rate can be remarkably increased. The preparation method comprises the following steps: (1) reacting fly ash in an acid solution to obtain an aluminum salt solution; (2) adding an alkaline solution and a template agent into the aluminum salt solution, carrying out hydrothermal reaction at 80-120 DEG C, separating out a solid-phase part, and washing with water; and (3) drying the washed solid phase part, and then roasting at the temperature of 500-1100 DEG C to obtain the alumina carrier, and (4) impregnating and loading a zinc element and a copper element on the alumina carrier by an impregnation method, drying, and roasting at 300-350 DEG C to obtain the catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of synthesizing methanol from syngas, and particularly relates to a catalyst for synthesizing methanol from syngas with a high specific surface area, a preparation method thereof, and an application thereof. Background Art

[0002] Chinese Patent Application CN 110314688 A discloses a preparation method of a methanol synthesis catalyst. The method includes: performing a coprecipitation reaction on a solution containing a precursor of an active component and a coprecipitating agent, and then successively performing filtration, washing, drying, and calcination. Among them, during the coprecipitation reaction process and / or after the coprecipitation reaction ends, an acidic gas is introduced into the reaction system.

[0003] Chinese Patent Application CN 109289855 A discloses a syngas methanol catalyst and a preparation method thereof. The syngas methanol catalyst of the present invention includes the following components in parts by mass: CuO: 55-75 parts, ZnO: 15-25 parts, Al2O3: 10-15 parts, MgO: 1-3 parts. The preparation method adopts a two-step simultaneous precipitation method, and simultaneously mixes the precipitate formed by co-precipitating Zn 2+ , Al 3+ to form a precipitate together and Cu 2+ , Zn 2+ , Al 3+ and Mg 2+ to form a precipitate together, and then through filtration, washing, drying, and calcination, the syngas methanol catalyst is prepared.

[0004] The preparation of traditional methanol catalysts mainly uses the precipitation method, and there are also the most reports on the precipitation method. In the coprecipitation method, the catalyst forms copper-zinc coprecipitates and copper-zinc-aluminum coprecipitates. The Al2O3 obtained by finally drying and calcining is amorphous, and its effect of separating the active components of the catalyst and avoiding the migration of the active components is limited. Moreover, the coprecipitation method has the disadvantages of relatively complex process, high control difficulty, and high preparation cost. Summary of the Invention

[0005] The present invention provides a catalyst for synthesizing methanol from syngas with a high specific surface area, a preparation method thereof, and an application thereof. The process provided by the present invention does not use the coprecipitation method but uses the impregnation method to prepare the catalyst for synthesizing methanol from syngas. The process is easier to control than the traditional coprecipitation method, and the process is simple. The obtained catalyst can obtain better catalyst performance with less CuO and ZnO usage, can significantly improve the CO conversion rate in the application of synthesizing methanol from syngas, and at the same time has a lower catalyst cost.

[0006] In order to achieve its purpose, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a method for preparing a methanol synthesis catalyst with a high specific surface area from syngas. The preparation method includes the following steps:

[0008] (1) React fly ash in an acidic solution to obtain an aluminum salt solution;

[0009] (2) Add an alkaline solution and a template agent to the aluminum salt solution, and carry out a hydrothermal reaction at 80 - 120 °C (such as 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, etc.). Separate the solid phase part therein and carry out water washing; for example, separate the solid phase part from the mixture obtained by the hydrothermal reaction by centrifugation; carry out water washing, for example, wash until the conductivity of the washing liquid does not exceed 50 us / cm;

[0010] (3) Dry the solid phase part after water washing, and then carry out calcination at 500 - 1100 °C (such as 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1100 °C, etc.) to obtain the alumina support;

[0011] (4) Impregnate and load zinc and copper elements on the alumina support by the impregnation method, dry and then calcine at 300 - 350 °C (such as 300 °C, 320 °C, 350 °C, etc.) to obtain the catalyst;

[0012] In the catalyst, the mass content of CuO is 30% - 56%, the mass content of ZnO is 5% - 30%, and the total mass content of CuO and ZnO is 60% - 85%.

[0013] The present invention uses fly ash as a raw material, first reacts in an acidic solution to obtain an aluminum salt solution, then carries out a hydrothermal reaction with an alkaline solution and a template agent at 80 - 120 °C. After water washing and drying, it is calcined at 500 - 1100 °C. The support obtained based on this process is impregnated with copper and zinc, and calcined at 300 - 350 °C. The obtained catalyst has a high specific surface area, and this catalyst has better catalytic performance in the application of syngas to methanol, can achieve a higher CO conversion rate, and this catalyst can obtain good catalytic performance with a relatively low dosage of active components. The present invention uses the impregnation method to load active components on the alumina support. Compared with the traditional co - precipitation method for preparing methanol synthesis catalysts from syngas, the process is easy to control and the process flow is simple; using solid waste fly ash as the aluminum source, the catalyst prepared by a specific process has a high specific surface area, and the obtained catalyst has an improved mass transfer rate of reaction gas. It can not only reduce the dosage of CuO and ZnO, but also take into account the better reaction efficiency of syngas to methanol, while reducing the catalyst cost. The catalyst provided by the present invention, compared with the existing catalysts, can achieve a higher CO conversion rate, such as up to 57.8% or higher, under the condition of a relatively low Cu content.

[0014] In the present invention, the hydrothermal reaction in step (2) is carried out at 80 - 120 °C, the calcination in step (3) is carried out at 500 - 1100 °C, and the calcination in step (4) is carried out at 300 - 350 °C. The inventor of the present invention has found that when the preparation of the catalyst of the present invention is carried out while satisfying the above temperature requirements, it is beneficial to obtain a synthesis gas to methanol catalyst with better performance.

[0015] In the present invention, in the catalyst, the mass content of CuO is 30% - 56%, such as 30%, 40%, 50%, 55%, etc.; the mass content of ZnO is 5% - 30%, such as 5%, 10%, 15%, 20%, 25%, 30%, etc.; and the total mass content of CuO and ZnO is 60% - 85%, such as 60%, 65%, 70%, 75%, 80%, 85%, etc.

[0016] In some embodiments, in step (2), the template agent is one or more of cetyltrimethylammonium bromide (CTAB), polyether F127, polyether P123, and sodium dodecylbenzenesulfonate, preferably one or more of CTAB, F127, and P123. The inventor of the present invention has found that based on the alumina support prepared by using the preferred template agent to prepare the synthesis gas to methanol catalyst of the present invention, the obtained catalyst has improved catalytic performance.

[0017] In some embodiments, in step (2), the mass ratio of the amount of the template agent to the aluminum salt solution is 8:1 - 12:1, such as 8:1, 10:1, 12:1, etc.

[0018] In some embodiments, in step (2), the time of the hydrothermal reaction is 8 - 20 h, and the hydrothermal reaction can be carried out in a polytetrafluoroethylene hydrothermal reaction kettle.

[0019] In some embodiments, in step (2), the basic reagent in the basic solution is an inorganic base, such as one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the concentration of the basic solution is, for example, 5 - 10 wt%. Preferably, the molar ratio of the amount of the basic solution calculated as OH - to Al 3+ in the aluminum salt solution is (3 - 5):1, such as 3:1, 4:1, 5:1, etc.

[0020] In some embodiments, in step (4), a two-step impregnation method is adopted. Specifically, for example, in some embodiments, the alumina support is first impregnated with a zinc salt solution, then dried, and then further impregnated with a copper salt solution, and then dried and calcined. In some embodiments, in step (4), the alumina support is first impregnated with a copper salt solution, then dried, and then further impregnated with a zinc salt solution, and then dried and calcined. In step (4), the drying in each stage is carried out at 80-120°C, and the drying time in each stage is, for example, 3-12 h.

[0021] In a preferred embodiment, in step (4), a one-step impregnation method is adopted. Specifically, the alumina support is impregnated with a mixed solution of a zinc salt and a copper salt, and then dried and calcined. The drying temperature is, for example, 80-120°C, and the drying time is, for example, 3-6 h. The inventors have found that when the alumina support is impregnated with a mixed solution of a zinc salt and a copper salt in one step, compared with impregnating the zinc salt solution and the copper salt solution separately in two steps, the obtained catalyst has more excellent catalytic performance for synthesizing methanol from syngas.

[0022] In some embodiments, the copper salt is selected from one or more of copper sulfate, copper nitrate, copper acetate, copper formate, and copper chloride;

[0023] In some embodiments, the zinc salt is selected from one or more of zinc sulfate, zinc nitrate, zinc acetate, zinc formate, and zinc chloride;

[0024] In some embodiments, in step (4), the temperature for carrying out the drying is 80-120°C;

[0025] In some embodiments, in step (4), the heating rate for carrying out the calcination is 2-5°C / min, and the calcination time is, for example, 4-8 h.

[0026] In some embodiments, in step (4), the impregnation is carried out at 23-60°C, and the impregnation time is, for example, 4-12 h.

[0027] In some embodiments, in step (1), the acidic solution is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid; the concentration of the acidic solution can be, for example, 10-20 wt%.

[0028] In some embodiments, in step (1), the molar ratio of the acidic solution in terms of H + to the alumina in the fly ash is (6-8):1, such as 6:1, 7:1, 8:1, etc.;

[0029] In some embodiments, in step (1), the reaction temperature is 100-120°C, the reaction pressure is 0-0.3 MPa, and the reaction time is, for example, 6-8 hours.

[0030] In some embodiments, in step (3), the heating rate of the calcination is 2-8 °C / min, and the calcination time is, for example, 2-8 h.

[0031] In the preparation method of the present invention, in step (3), the crystal form of the alumina support is γ-Al2O3, and the specific surface area is, for example, 240-360 m 2 / g. The alumina support with the γ-Al2O3 crystal form has a nanoscale particle size.

[0032] The second aspect of the present invention provides a methanol synthesis catalyst with a high specific surface area from syngas. The catalyst includes an alumina support and CuO and ZnO supported on the alumina support;

[0033] Based on the total mass of the catalyst, the mass content of CuO is 30%-56%, the mass content of ZnO is 5%-30%, and the total mass content of CuO and ZnO is 60%-85%;

[0034] The crystal form of the alumina support is γ-Al2O3;

[0035] Preferably, the specific surface area of the catalyst is 150-220 m 2 / g;

[0036] Preferably, the catalyst is prepared by the method described above.

[0037] The third aspect of the present invention provides the use of the catalyst prepared by the preparation method described above or the catalyst described above in the process of synthesizing methanol from syngas.

[0038] The technical solution provided by the present invention has the following beneficial effects:

[0039] The CuZnAl catalyst prepared by the present invention using fly ash as the aluminum source by the impregnation method has better catalytic activity for synthesizing methanol from syngas, and can achieve good catalytic performance with a lower dosage of active components. The preparation process of the present invention has the characteristics of simple process, easy control, and low cost compared with the traditional co-precipitation method. Description of the Drawings

[0040] Figure 1 XRD results of the alumina support obtained in step (3) of Example 1. Detailed Embodiments

[0041] To facilitate the understanding of the present invention, the present invention will be further described below in conjunction with embodiments. It should be understood that the following embodiments are only for better understanding of the present invention, and do not mean that the present invention is limited only to the following embodiments.

[0042] Where specific experimental procedures or conditions are not specified in the examples, the operations or conditions of the corresponding conventional experimental procedures in this technical field can be followed. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0043] Fly ash: Fly ash from the alumina pilot plant of Guoneng Zhungeer Energy Group;

[0044] Polyether F127: Macklin reagent P822479;

[0045] CTAB: Macklin reagent H811115;

[0046] Polyether P123: Macklin reagent P822487.

[0047] Example 1 (impregnating with copper nitrate first and then with zinc nitrate)

[0048] (1) Mix fly ash and hydrochloric acid (concentration 18 wt%), and make the molar ratio of hydrochloric acid used, calculated as HCl, to alumina in fly ash be 7:1. React and stir at 100 °C under normal pressure for 6 h to completely dissolve the alumina in the fly ash. After filtration, an aluminum salt solution is obtained.

[0049] (2) Add an aqueous NaOH solution to the aluminum salt solution obtained in step (1) according to the molar ratio of OH - in the aqueous NaOH solution to Al 3+ in the aluminum salt solution being 3.5:1. Add a template agent (F127) according to the mass ratio of the template agent to the aluminum salt solution of 10:1. Then place the mixture in a polytetrafluoroethylene hydrothermal reaction kettle and conduct a hydrothermal reaction at 100 °C for 12 h. After centrifuging the mixture, wash the solid phase part with deionized water until the conductivity of the washing liquid is not higher than 50 μS / cm.

[0050] (3) Dry the solid phase part washed in step (2) at 95 °C for 3 h, and then heat it to 900 °C at a rate of 5 °C / min and calcine for 2 h to obtain a high specific surface area alumina support with a crystal form of γ-Al2O3 (for the characterization results, see Figure 1 ), and the specific surface area is 281.3 m 2 / g.

[0051] (4) Dissolve 121.5 g of copper nitrate trihydrate in 100 g of deionized water at 45 °C. Wait for it to completely dissolve to prepare a copper nitrate solution, and impregnate the prepared 23.46 g of alumina support with the copper nitrate solution at 45 °C for 3 h; then dry it at 100 °C for 5 h to obtain Cu-Al;

[0052] Next, 80.46 g of zinc nitrate hexahydrate was dissolved in 100 g of deionized water at 45 °C. After complete dissolution, a zinc nitrate solution was prepared, and the obtained Cu-Al from the previous step was impregnated with the zinc nitrate solution at 45 °C for 3 h. Then, it was dried at 100 °C for 5 h. Subsequently, the temperature was raised to 350 °C at a rate of 5 °C / min and calcined at 350 °C for 4 h to obtain the CuZnAl catalyst.

[0053] The catalyst obtained in this example contains the following components with the following mass percentages: CuO 47%, ZnO 26%, and Al2O3 27%. The specific surface area of the prepared catalyst is 194.6 cm 2 / g.

[0054] The catalyst was tested for its activity under the conditions of a reaction temperature of 230 °C, a reaction pressure of 5 Mpa, a space velocity of 10000 h -1 and a hydrogen-carbon ratio of 5.2 (the feed gas is syngas, with a composition of H2: 80%, CO: 13%, CO2: 2%, N2: 5%, and the percentages are volume percentages). The CO conversion rate was 56.9%.

[0055] Example 2 (One-step impregnation of copper nitrate and zinc nitrate)

[0056] (1) Fly ash and hydrochloric acid (with a concentration of 20 wt%) were mixed, and the molar ratio of HCl in the hydrochloric acid used to alumina in the fly ash was 6.5:1. The mixture was reacted and stirred at 100 °C and atmospheric pressure for 6 h to completely dissolve the alumina in the fly ash. After filtration, an aluminum salt solution was obtained.

[0057] (2) An aqueous NaOH solution was added to the aluminum salt solution obtained in step (1) according to a molar ratio of OH- in the aqueous NaOH solution to Al 3+ in the aluminum salt solution of 4:1. A template agent (CTAB) was added according to a mass ratio of 10:1 to the aluminum salt solution. Then, the mixture was placed in a polytetrafluoroethylene hydrothermal reaction kettle and subjected to a hydrothermal reaction at 100 °C for 12 h. After centrifuging the mixture, the solid phase part was washed with deionized water until the conductivity of the washing liquid was not higher than 50 us / cm.

[0058] (3) The solid phase part washed in step (2) was dried at 95 °C for 3 h, and then the temperature was raised to 800 °C at a rate of 5 °C / min and calcined for 2 h to obtain a high specific surface area alumina support with a crystal form of γ-Al2O3 and a specific surface area of 327.8 m 2 / g.

[0059] (4) Dissolve 109.35 g of copper nitrate trihydrate in 100 g of deionized water at 45°C until it is completely dissolved to prepare a copper nitrate solution; dissolve 74.5 g of zinc nitrate hexahydrate in 100 g of deionized water at 45°C until it is completely dissolved to prepare a zinc nitrate solution; fully mix the two solutions prepared above to obtain a Cu-Zn solution, and impregnate it onto 30.6 g of an alumina carrier at 45°C for 3 hours; then dry it at 100°C for 5 hours, heat it to 350°C at a rate of 5°C / min, and calcine it at 350°C for 4 hours to obtain a CuZnAl catalyst.

[0060] The catalyst obtained in this example includes the following components by mass: CuO 42%, ZnO 23%, Al2O3 35%; the specific surface area of the prepared catalyst is 216.7 cm 2 / g.

[0061] The catalyst activity was tested under the same experimental conditions as in Example 1, and the CO conversion rate was 57.8%.

[0062] Example 3 (Immersing zinc nitrate first and then copper nitrate)

[0063] (1) Fly ash and hydrochloric acid (concentration of 15 wt%) are mixed, and the molar ratio of the hydrochloric acid used, calculated as HCl, to the aluminum oxide in the fly ash is 7.5:1. The reaction is stirred at 100° C. and normal pressure for 6 hours to completely dissolve the aluminum oxide in the fly ash, and an aluminum salt solution is obtained after filtering.

[0064] (2) According to the reaction between OH- in NaOH aqueous solution and Al in aluminum salt solution 3+ A NaOH aqueous solution is added to the aluminum salt solution obtained in step (1) at a molar ratio of 5:1, and a template is added according to a mass ratio of the template (P123) to the aluminum salt solution of 10:1. The mixture is then placed in a polytetrafluoroethylene hydrothermal reactor and subjected to a hydrothermal reaction at 100°C for 12 hours. The mixture is centrifuged and the solid phase is washed with deionized water until the conductivity of the washing liquid is not higher than 50us / cm.

[0065] (3) The solid phase washed in step (2) was dried at 95°C for 3 h, and then calcined at 600°C at a rate of 5°C / min for 2 h to obtain an alumina carrier with a high specific surface area, the crystal form of which was γ-Al2O3 and the specific surface area of which was 286.2 m 2 / g.

[0066] (4) dissolving 89.4 g of zinc nitrate hexahydrate in 100 g of deionized water at 45° C., and preparing a zinc nitrate solution until the zinc nitrate solution is completely dissolved, and impregnating the zinc nitrate solution onto 14.28 g of the prepared alumina support at 45° C. for 3 h; and then drying at 100° C. for 5 h to obtain Zn-Al;

[0067] Then, 136.08 g of copper nitrate trihydrate was dissolved in 100 g of deionized water at 45 °C. After complete dissolution, a copper nitrate solution was prepared, and the previously obtained Zn-Al was impregnated with the copper nitrate solution at 45 °C for 3 h. Then, it was dried at 100 °C for 5 h. Subsequently, the temperature was raised to 350 °C at a rate of 3 °C / min and calcined at 350 °C for 4 h to obtain a CuZnAl catalyst.

[0068] The catalyst obtained in this example contains the following components with the following mass percentages: CuO 54%, ZnO 29%, Al2O3 17%. The specific surface area of the prepared catalyst is 163.4 cm 2 / g.

[0069] Referring to Example 1, the catalytic activity was tested under the same experimental conditions, and the CO conversion rate was 57.3%.

[0070] Example 4 (compared with Example 3, using a different template agent)

[0071] (1) Fly ash and hydrochloric acid (with a concentration of 15 wt%) were mixed, and the molar ratio of HCl in the hydrochloric acid used to alumina in the fly ash was 7.5:1. The mixture was reacted and stirred at 100 °C under atmospheric pressure for 6 h to completely dissolve the alumina in the fly ash. After filtration, an aluminum salt solution was obtained.

[0072] (2) An aqueous NaOH solution was added to the aluminum salt solution obtained in step (1) according to a molar ratio of OH- in the aqueous NaOH solution to Al 3+ in the aluminum salt solution of 5:1. A template agent (sodium dodecylbenzenesulfonate DBS) was added according to a mass ratio of 10:1 to the aluminum salt solution. Then, the mixture was placed in a polytetrafluoroethylene hydrothermal reaction kettle and hydrothermally reacted at 100 °C for 12 h. After centrifuging the mixture, the solid phase was washed with deionized water until the conductivity of the washing liquid was not higher than 50 μS / cm.

[0073] (3) The solid phase washed in step (2) was dried at 95 °C for 3 h and then calcined at 600 °C for 2 h at a rate of 5 °C / min to obtain a high specific surface area alumina support with a crystal form of γ-Al2O3 and a specific surface area of 226.7 m 2 / g.

[0074] (4) 89.4 g of zinc nitrate hexahydrate was dissolved in 100 g of deionized water at 45 °C. After complete dissolution, a zinc nitrate solution was prepared, and the zinc nitrate solution was impregnated onto the prepared 14.28 g of alumina support at 45 °C for 3 h. Then, it was dried at 100 °C for 5 h to obtain Zn-Al.

[0075] Then, 136.08 g of copper nitrate trihydrate was dissolved in 100 g of deionized water at 45 °C. After complete dissolution, a copper nitrate solution was prepared. The copper nitrate solution was impregnated into the previously obtained Zn-Al at 45 °C for 3 h; then dried at 100 °C for 5 h; then heated to 350 °C at a rate of 3 °C / min and calcined at 350 °C for 4 h to obtain a CuZnAl catalyst;

[0076] The catalyst obtained in this example contains the following components with the following mass contents: CuO 54%, ZnO 29%, Al2O3 17%; the specific surface area of the prepared catalyst is 126.4 cm 2 / g.

[0077] Referring to Example 1, the catalyst activity was tested under the same experimental conditions, and the CO conversion rate was 53.2%

[0078] Compared with Example 3, this example did not use the preferred template agent type, and as a result, the activity of the obtained catalyst decreased significantly.

[0079] Example 5

[0080] Referring to Example 3, the catalyst was prepared, except that: in step (4), a one-step impregnation process was used. The zinc nitrate solution and the copper nitrate solution were fully mixed to obtain a mixed solution, and then the mixed solution was impregnated onto the alumina support at 45 °C for 3 h. The remaining operations and conditions were all carried out with reference to Example 3 and will not be elaborated here.

[0081] The test result of the catalyst activity was: the CO conversion rate was 59.3%.

[0082] Comparative Example 1

[0083] (1) Fly ash and hydrochloric acid (concentration 10 wt%) were mixed, and the molar ratio of the hydrochloric acid used, calculated as HCl, to alumina in the fly ash was 7:1. At 100 °C and atmospheric pressure, the mixture was reacted and stirred for 6 h to completely dissolve the alumina in the fly ash. After filtration, an aluminum salt solution was obtained.

[0084] (2) An aqueous NaOH solution was added to the aluminum salt solution obtained in step (1) according to the molar ratio of OH- in the aqueous NaOH solution to Al 3+ in the aluminum salt solution of 3.5:1. A template agent (F127) was added according to the mass ratio of the template agent to the aluminum salt solution of 10:1. Then the mixture was placed in a polytetrafluoroethylene hydrothermal reaction kettle and subjected to hydrothermal reaction at 100 °C for 12 h. After centrifuging the mixture, the solid phase part was washed with deionized water until the conductivity of the washing liquid was not higher than 50 us / cm.

[0085] (3) Dry the solid phase portion washed in step (2) at 95 °C for 3 h, then raise the temperature to 450 °C at a rate of 5 °C / min and calcine for 2 h to obtain an alumina support with a crystal form of γ-Al2O3 and a specific surface area of 93.7 m 2 / g.

[0086] (4) Dissolve 145.8 g of copper nitrate trihydrate in 100 g of deionized water at 45 °C. Wait for it to dissolve completely to prepare a copper nitrate solution. Then, impregnate the prepared 10.2 g of alumina support with the copper nitrate solution at 45 °C and impregnate for 3 h; then dry at 100 °C for 5 h to obtain Cu-Al;

[0087] Then dissolve 89.4 g of zinc nitrate hexahydrate in 100 g of deionized water at 45 °C. Wait for it to dissolve completely to prepare a zinc nitrate solution. Then, impregnate the previously obtained Cu-Al with the zinc nitrate solution at 45 °C and impregnate for 3 h. Then dry at 100 °C for 5 h; then raise the temperature to 350 °C at a rate of 6 °C / min and calcine at 350 °C for 4 h to obtain a CuZnAl catalyst;

[0088] The catalyst obtained in this example includes the following components with the following mass contents: CuO 58%, ZnO 29%, Al2O3 13%; the specific surface area of the prepared catalyst is 79.6 cm 2 / g.

[0089] Refer to Example 1 to test the catalyst activity under the same experimental conditions. The CO conversion rate is 42.7%.

[0090] Compared with Example 1 in this comparative example, the calcination temperature in step (3) did not reach 500 - 1100 °C, and as a result, the activity of the obtained catalyst decreased significantly.

[0091] Comparative Example 2

[0092] Use the precipitation method to prepare the catalyst

[0093] (1) Prepare an aqueous solution of 1 mol / L from 33.77 g of aluminum nitrate nonahydrate and an aqueous solution with a sodium ion concentration of 2.4 mol / L from 13.99 g of anhydrous sodium carbonate. Co-precipitate the two at 80 °C with equal volume and equal flow rate in parallel, and control the reaction pH at 7 - 7.5 to obtain a precipitate solution A.

[0094] (2) Prepare an aqueous solution with a total metal ion concentration of 1 mol / L from 144.96 g of copper nitrate trihydrate and 89.24 g of zinc nitrate hexahydrate; prepare a 1 mol / L sodium carbonate solution from 95.4 g of anhydrous sodium carbonate. Co-precipitate these two solutions at 80 °C with equal volume and equal flow rate in parallel, and control the reaction pH at 7 - 7.5 to obtain a precipitate solution B.

[0095] The obtained precipitate solutions A and B were mixed at a volume ratio of 1:10, aged at 80 °C for 2 h, filtered, washed, dried, and then heated to 350 °C at a rate of 3 °C / min and calcined at 350 °C for 4 h to obtain the finished catalyst. The obtained catalyst included the following components in mass percentages: CuO 63%, ZnO 32%, and Al2O3 5%. The specific surface area of the prepared catalyst was 93.2 cm 2 / g.

[0096] The catalyst activity was tested under the same experimental conditions as in Example 1, and the CO conversion rate was 51.6%.

[0097] Compared with the example, the dosages of the active components CuO and ZnO were significantly increased in this comparative example, but the activity of the catalyst was significantly lower than that of the catalyst obtained in the example.

[0098] Comparative Example 3

[0099] It was carried out with reference to Example 1, except that: the temperature of the hydrothermal reaction in step (2) was 180 °C.

[0100] Catalyst activity test result: The CO conversion rate was 52.2%.

[0101] Comparative Example 4

[0102] It was carried out with reference to Example 2, only different in that: the calcination temperature in step (3) was 400 °C.

[0103] Catalyst activity test result: The CO conversion rate was 49.5%.

[0104] Comparative Example 5

[0105] It was carried out with reference to Example 2, only different in that: the calcination temperature in step (4) was 270 °C.

[0106] Catalyst activity test result: The CO conversion rate was 48.7%.

[0107] Comparative Example 6

[0108] It was carried out with reference to Example 3, only different in that: the calcination temperature in step (4) was 450 °C.

[0109] Catalyst activity test result: The CO conversion rate was 44.3%.

[0110] Comparative Example 7

[0111] It was carried out with reference to Example 3, only different in that: by adjusting the dosages of zinc nitrate hexahydrate, copper nitrate trihydrate, and alumina support in step (4), the mass content of CuO in the prepared catalyst was 35%, the mass content of ZnO was 20%, and the rest was Al2O3.

[0112] Catalyst activity test result: The CO conversion rate is 38.2%.

[0113] From the experimental results of Comparative Example 7, it can be seen that when the total mass content of CuO and ZnO fails to reach 60 - 85%, the activity of the obtained catalyst significantly decreases. The inventor also found in the experiment that when the total mass content of CuO and ZnO is too high, exceeding 85% by adjusting the dosages of zinc nitrate hexahydrate, copper nitrate trihydrate, and alumina support in step (4), the specific surface area provided by the alumina support is limited, and at the same time, the active components are prone to aggregation and difficult to be uniformly loaded, resulting in a significant decrease in the performance of the obtained catalyst.

[0114] It is easy to understand that the above-mentioned embodiments are merely examples for clear illustration and do not mean that the present invention is limited thereto. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of a methanol synthesis catalyst from syngas with high specific surface area, characterized in that, The preparation method comprises the following steps: (1) React fly ash in an acidic solution to obtain an aluminum salt solution; (2) Add an alkaline solution and a template agent to the aluminum salt solution, carry out a hydrothermal reaction at 80 - 120 °C, separate the solid phase portion therein and perform water washing; (3) Dry the washed solid phase portion, and then carry out calcination at 500 - 1100 °C to obtain the alumina support; (4) Impregnate and load zinc element and copper element on the alumina support by an impregnation method, dry and then carry out calcination at 300 - 350 °C to obtain the catalyst; In the catalyst, the mass content of CuO is 30% - 56%, the mass content of ZnO is 5% - 30%, and the total mass content of CuO and ZnO is 60% - 85%.

2. The preparation method according to claim 1, characterized in that, In step (2), the template agent is one or more of CTAB, F127, P123, sodium dodecylbenzenesulfonate; preferably one or more of CTAB, F127, P123.

3. The preparation method according to claim 1 or 2, characterized in that, In step (2), the mass ratio of the dosage of the template agent to the mass of the aluminum salt solution is 8:1 - 12:1; And / or, in step (2), the time of the hydrothermal reaction is 8 - 20 h; And / or, in step (2), the basic reagent in the basic solution is an inorganic base, such as one or more of sodium hydroxide, potassium hydroxide, and ammonia water; preferably, the dosage of the basic solution calculated as OH - and the molar ratio of Al 3+ in the aluminum salt solution is (3-5):

1.

4. The preparation method according to any one of claims 1-3, characterized in that, In step (4), impregnate the alumina support with a mixed solution of zinc salt and copper salt, and then carry out drying and calcination; Or, in step (4), first impregnate the alumina support with a zinc salt solution, then dry, continue to impregnate with a copper salt solution, and then carry out drying and calcination; Or, in step (4), first impregnate the alumina support with a copper salt solution, then dry, continue to impregnate with a zinc salt solution, and then carry out drying and calcination.

5. The preparation method according to claim 4, characterized in that The copper salt is selected from one or more of copper sulfate, copper nitrate, copper acetate, copper formate, and copper chloride; And / or, the zinc salt is selected from one or more of zinc sulfate, zinc nitrate, zinc acetate, zinc formate, and zinc chloride; And / or, in step (4), the temperature for carrying out the drying is 80 - 120 °C; And / or, in step (4), the heating rate for carrying out the calcination is 2 - 5 °C / min, and the calcination time is, for example, 4 - 8 h; And / or, in step (4), the impregnation is carried out at 23 - 60 °C.

6. The preparation method according to any one of claims 1-5, characterized in that, In step (1), the acidic solution is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid; and / or, in step (1), the molar ratio of the acidic solution calculated in terms of H + to the alumina in the fly ash is (6-8):1; And / or, in step (1), the reaction temperature is 100 - 120 °C, the reaction pressure is 0 - 0.3 MPa, and the reaction time is, for example, 6 - 8 hours.

7. According to the preparation method described in any one of claims 1-6, characterized in that, In step (3), the heating rate for carrying out the calcination is 2 - 8 °C / min, and the calcination time is, for example, 2 - 8 h.

8. The preparation method according to any one of claims 1-7, characterized in that, In step (3), the crystal form of the alumina support is γ-Al2O3, and the specific surface area is, for example, 240-360 m 2 / g.

9. A methanol synthesis catalyst from syngas with a high specific surface area, characterized in that, The catalyst comprises an alumina support and CuO and ZnO supported on the alumina support; Based on the total mass of the catalyst, the mass content of CuO is 30% - 56%, the mass content of ZnO is 5% - 30%, and the total mass content of CuO and ZnO is 60% - 85%; The crystal form of the alumina support is γ - Al2O3; Preferably, the specific surface area of the catalyst is 150 - 220 m 2 / g; Preferably, the catalyst is prepared by the method according to any one of claims 1 - 9.

10. The catalyst prepared by the preparation method according to any one of claims 1-8 or the catalyst according to claim 9 is used in the process of synthesizing methanol from syngas.

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