Methanol synthesis catalyst capable of adsorbing CO with high selectivity and preparation method of methanol synthesis catalyst

Abstract

The invention relates to the field of methanol synthesis catalysts, and particularly discloses a methanol synthesis catalyst capable of adsorbing CO with high selectivity and a preparation method of the methanol synthesis catalyst. The preparation method of the methanol synthesis catalyst capable of highly selectively adsorbing CO comprises the following steps: dropwise adding pyridine into a copper salt-zinc salt-nicotinic acid mixed aqueous solution at 10-40 DEG C, and reacting for 30-90 minutes to obtain a copper-zinc metal organic framework suspension; in the copper salt-zinc salt-nicotinic acid mixed aqueous solution, the molar ratio of the total amount of copper salt-zinc salt to nicotinic acid is 1: (1-3); reacting aluminum salt with alkali to obtain alumina gel; alumina gel and the copper-zinc metal organic framework turbid liquid are mixed, pulped and roasted, and the methanol synthesis catalyst capable of adsorbing CO with high selectivity is obtained. The preparation method of the methanol synthesis catalyst for highly selectively adsorbing CO has the advantages that the dispersibility and the thermal stability of the active components in the methanol synthesis catalyst are improved, and the CO adsorption performance and the conversion rate are further improved.

Description

Technical Field

[0001] This application relates to the field of catalysts, and more specifically, to a methanol synthesis catalyst with high selectivity for CO adsorption and a method for its preparation. Background Technology

[0002] In the synthesis of methanol via the reaction of hydrogen with carbon monoxide and / or carbon dioxide, the amount and rate of CO adsorption on the catalyst surface from the feed gas are among the key steps affecting methanol synthesis. Currently, the most mature methanol synthesis catalysts are copper-based catalysts, represented by the copper-zinc-aluminum system. These catalysts exhibit excellent CO adsorption performance, but industrially they are mostly prepared using co-precipitation methods. Although co-precipitation is simple and easy to implement, the resulting catalyst product has uneven dispersion of the active components, with CO adsorption selectivity typically around 50%. Furthermore, the active sites in the catalyst product are prone to aggregation and migration at high temperatures, significantly impacting adsorption efficiency and exhibiting poor stability.

[0003] Therefore, improving the dispersion of methanol synthesis catalysts and limiting the migration and aggregation of active substances under high-temperature conditions while preparing them in a simple and easy manner in industry is an urgent problem to be solved. Summary of the Invention

[0004] In order to obtain a methanol synthesis catalyst with high dispersibility and high thermal stability, this application provides a methanol synthesis catalyst with high selective adsorption of CO and a method for preparing the same.

[0005] In a first aspect, this application provides a method for preparing a methanol synthesis catalyst with high selective CO adsorption, employing the following technical solution:

[0006] A method for preparing a methanol synthesis catalyst with high selective CO adsorption includes the following steps:

[0007] Under stirring conditions, pyridine was added dropwise to a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 30-90 min to obtain a copper-zinc metal-organic framework suspension; the molar ratio of the total amount of copper salt and zinc salt to nicotinic acid in the mixed aqueous solution of copper salt, zinc salt, and nicotinic acid was 1:(1-3);

[0008] Aluminum salts are reacted with alkali to obtain aluminum gel; the aluminum gel is mixed with a copper-zinc metal-organic framework suspension and slurried, and then calcined to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0009] By adopting the above technical solution, the metal-organic framework material has the characteristics of uniform and regular dispersion of metal nodes. In this application, a metal-organic framework was prepared by using nicotinic acid as an organic ligand and pyridine-assisted synthesis. The catalytic active component copper and the co-catalytic active component zinc were doped into the metal-organic framework to form a copper-zinc metal-organic framework precursor with single-atom metal nodes doped with copper-zinc active centers. After the copper-zinc metal-organic framework precursor was combined with aluminum glue and calcined, the copper-zinc metal-organic framework precursor could form highly dispersed copper-zinc oxides in situ on the alumina support, thus obtaining a Cu-ZnO-Al2O3 methanol synthesis catalyst with atomically dispersed copper-zinc active components.

[0010] This application creatively grows copper and zinc together in the same metal-organic framework structure, resulting in a novel metal-organic framework structure with single-atom nodes of both copper and zinc. In this structure, the individual copper and zinc metal atoms are regularly separated by the organic ligand nicotinic acid, and are in a highly dispersed state. This helps to improve the accessibility of active sites, enhance the adsorption capacity of methanol synthesis catalyst for CO, and further improve the conversion rate and selectivity of the catalyst. Furthermore, the metal ions are arranged relatively closely, which can form strong intermetallic interactions, limit the migration and aggregation of active centers, and effectively reduce the possibility of excessive growth of copper particles before and after the reaction, thus effectively improving the selectivity and thermal stability of methanol synthesis catalyst.

[0011] This application controls the molar ratio of the total amount of copper-zinc salt to nicotinic acid to achieve a suitable distribution of active sites in the copper-zinc metal-organic framework precursor. This avoids the situation where the molar ratio of the total amount of copper-zinc salt to nicotinic acid is too large, resulting in an overly dense distribution of active sites per unit amount of copper-zinc metal-organic framework precursor and poor dispersion of active sites. This reduces the possibility of the methanol synthesis catalyst produced in this way having an overly vigorous catalytic reaction, catalyst sintering, and excessive by-products. At the same time, it avoids the situation where the molar ratio of the total amount of copper-zinc salt to nicotinic acid is too small, resulting in an excessively high nicotinic acid content and an insufficient content of copper and zinc active sites per unit amount of copper-zinc metal-organic framework precursor. This reduces the possibility of insufficient catalytic activity, poor CO adsorption effect, and poor conversion rate in the methanol synthesis catalyst produced in this way.

[0012] Preferably, in the copper-zinc-nicotinic acid mixed aqueous solution, the molar ratio of copper ions to zinc ions is (3-1):1.

[0013] By adopting the above technical solution and adjusting the molar ratio of copper to zinc, the main catalyst copper and the co-catalyst zinc have a better synergistic relationship, ensuring that the methanol synthesis catalyst has better catalytic activity and selectivity.

[0014] Preferably, the molar ratio of nicotinic acid to pyridine is (10-50):1.

[0015] Preferably, in the copper-zinc-nicotinic acid mixed aqueous solution, the concentration of copper salt is 0.1-3 mol / L, the concentration of zinc salt is 0.1-1 mol / L, and the concentration of nicotinic acid is 0.1-3 mol / L.

[0016] Preferably, the anions of the copper and zinc salts are selected from nitrate ions, acetate ions, and oxalate ions.

[0017] Preferably, the anion of the aluminum salt is selected from nitrate ions, acetate ions, and oxalate ions. More preferably, the copper salt, zinc salt, and aluminum salt have the same type of anion.

[0018] By adopting the above technical solution, it is beneficial to reduce heteroatom interference.

[0019] Preferably, the reaction temperature of the copper salt-zinc salt-nicotinic acid mixed aqueous solution with the pyridine is 10-40℃.

[0020] Preferably, the reaction involves adding alkali dropwise to an aluminum salt solution at 30-60°C until the solution pH reaches 7.0-9.0, then aging for 30-90 minutes to obtain aluminum gel.

[0021] Preferably, the molar ratio of aluminum in the aluminum glue to the total amount of copper and zinc in the copper salt-zinc salt-nicotinic acid mixed aqueous solution is 1:(1-6).

[0022] By adopting the above technical solution, the copper-zinc active centers on the alumina carrier can achieve high dispersibility and suitable density.

[0023] Preferably, the alkali is selected from one of NaOH, NH3·H2O, NaHCO3, and Na2CO3.

[0024] Preferably, the processing temperature of the mixing and pulping step is 30-60℃ and the pulping time is 30-90min; the roasting temperature of the roasting step is 300-400℃ and the roasting time is 30-60min.

[0025] Secondly, this application provides a methanol synthesis catalyst with high selectivity for CO adsorption, employing the following technical solution:

[0026] A methanol synthesis catalyst with high selective CO adsorption is prepared by the above-mentioned method for preparing a methanol synthesis catalyst with high selective CO adsorption.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. This application creatively grows copper and zinc together in the same metal-organic framework structure to obtain a novel metal-organic framework structure with single-atom nodes of copper and zinc. In the structure, the individual metal atoms of copper and zinc are regularly separated by the organic ligand nicotinic acid and are in a highly dispersed state, which helps to improve the accessibility of active sites, improve the adsorption capacity of methanol synthesis catalyst for CO, and further improve the conversion rate and selectivity of the catalyst.

[0029] 2. The methanol synthesis catalyst of this application has a relatively close arrangement of metal ions, which can form a strong metal-to-metal interaction, restricting the migration and aggregation of active centers, and effectively reducing the possibility of excessive growth of copper particles before and after the reaction, thereby effectively improving the selectivity and thermal stability of the methanol synthesis catalyst.

[0030] 3. This application achieves a suitable distribution of active centers in the copper-zinc metal-organic framework precursor by controlling the total amount of copper-zinc salts and the molar ratio of nicotinic acid. Attached Figure Description

[0031] Figure 1 These are the XRD patterns of Cu-Zn-MOF in Example 1, Cu-MOF in Comparative Example 2, and Zn-MOF in Comparative Example 3. Detailed Implementation

[0032] To further aid in understanding the technical solution of the present invention, several specific implementation examples are provided below to describe the technical solution of the present invention in more detail. All of these described embodiments are only some embodiments of the present invention, and not all of them.

[0033] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments; and the reaction devices, monomer compounds, etc. involved in the following embodiments are all commercially available.

[0034] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0035] The following examples further illustrate the present invention, but the invention is not limited thereto. Unless otherwise specified in the examples, all percentages (%) are mass percentages.

[0036] Example

[0037] Example 1

[0038] This embodiment discloses a methanol synthesis catalyst with high selectivity for CO adsorption, which is prepared by the following steps:

[0039] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 2 mol / L nicotinic acid was prepared.

[0040] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF suspension.

[0041] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0042] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60℃ for 60 min, and then calcined at 350℃ for 40 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0043] Example 2

[0044] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0045] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1.5 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 3 mol / L nicotinic acid was prepared.

[0046] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF (copper-zinc metal-organic framework) suspension.

[0047] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O was added dropwise to the solution at 60℃, and the mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0048] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 30°C for 60 min, and then calcined at 350°C for 40 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0049] Example 3

[0050] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0051] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 1.5 mol / L nicotinic acid was prepared.

[0052] 0.05 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid at 10 °C under vigorous stirring. The reaction was carried out for 90 min to obtain a Cu-Zn-MOF suspension.

[0053] 0.25 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L NaOH solution was added dropwise to the solution at 30°C. The mixture was stirred until the pH of the mixed solution reached 9.0, which was the reaction endpoint. The solution was then aged for 90 min to obtain aluminum gel.

[0054] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 40°C for 90 min, and then calcined at 300°C for 60 min to obtain a methanol synthesis catalyst with high selective CO adsorption.

[0055] Example 4

[0056] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0057] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 1 mol / L zinc nitrate, and 2 mol / L nicotinic acid was prepared.

[0058] 0.04 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid at 40 °C under vigorous stirring. The reaction was carried out for 30 min to obtain a Cu-Zn-MOF suspension.

[0059] 1 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L NaHCO3 solution was added dropwise to the solution at 40℃. The mixture was stirred until the pH of the mixed solution reached 8.0, which was the reaction endpoint. The solution was then aged for 30 minutes to obtain aluminum gel.

[0060] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 50°C for 30 min, and then calcined at 400°C for 30 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0061] Example 5

[0062] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0063] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 0.5 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 3 mol / L nicotinic acid was prepared.

[0064] 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid at 50 °C with vigorous stirring. The reaction was carried out for 45 min to obtain a Cu-Zn-MOF suspension.

[0065] 1 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L NaHCO3 solution was added dropwise to the solution at 50℃. The mixture was stirred until the pH of the mixed solution reached 7.5, which was the reaction endpoint. The solution was then aged for 30 minutes to obtain aluminum gel.

[0066] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60℃ for 45 min, and then calcined at 330℃ for 50 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0067] Example 6

[0068] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0069] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 2.5 mol / L nicotinic acid was prepared.

[0070] 0.2 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid at 15 °C with vigorous stirring. The reaction was carried out for 75 min to obtain a Cu-Zn-MOF suspension.

[0071] 1.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L NaHCO3 solution was added dropwise to the solution at 45℃. The mixture was stirred until the pH of the mixed solution reached 8.5, which was the reaction endpoint. The solution was then aged for 75 min to obtain aluminum gel.

[0072] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 45°C for 75 min, and then calcined at 380°C for 35 min to obtain a methanol synthesis catalyst with high selective CO adsorption.

[0073] Example 7

[0074] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0075] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1.5 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 3 mol / L nicotinic acid was prepared.

[0076] 0.25 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt and nicotinic acid at 35 °C with vigorous stirring, and the reaction was carried out for 50 min to obtain a Cu-Zn-MOF suspension.

[0077] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L NaHCO3 solution was added dropwise to the solution at 55℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 50 min to obtain aluminum gel.

[0078] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 35°C for 50 min, and then calcined at 350°C for 40 min to obtain a methanol synthesis catalyst with high selective CO adsorption.

[0079] Example 8

[0080] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0081] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 1.5 mol / L nicotinic acid was prepared.

[0082] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF suspension.

[0083] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0084] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60℃ for 60 min, and then calcined at 350℃ for 40 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0085] Example 9

[0086] The only difference between this embodiment and Example 1 is that the methanol synthesis catalyst with high selective CO adsorption is prepared by the following steps:

[0087] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 6 mol / L nicotinic acid was prepared.

[0088] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF suspension.

[0089] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0090] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60℃ for 60 min, and then calcined at 350℃ for 40 min to obtain a methanol synthesis catalyst with high selective adsorption of CO.

[0091] Comparative Example

[0092] Comparative Example 1

[0093] The only difference between this comparative example and Example 1 is that this comparative example discloses a method for preparing a methanol synthesis catalyst, including the following steps:

[0094] Dissolve 230g of copper nitrate and 100g of zinc nitrate in 1L of deionized water to obtain solution A, heat to 70℃ and set aside;

[0095] Dissolve 250g of NaHCO3 in 3L of deionized water to obtain solution B, heat to 70℃ and set aside.

[0096] Under stirring conditions, solution A was added to solution B to carry out the reaction, the temperature was controlled at 70℃, the final pH value was 7.0, after color change and aging, it was washed; then 12.5g of alumina support was added, and after washing, filtration, drying, calcination and molding, methanol synthesis catalyst was obtained.

[0097] Comparative Example 2

[0098] The only difference between this comparative example and Example 1 is that the preparation method of the methanol synthesis catalyst is as follows:

[0099] A copper salt-nicotinic acid mixed aqueous solution with a copper nitrate concentration of 1.5 mol / L and a nicotinic acid concentration of 2 mol / L was prepared.

[0100] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a copper salt-nicotinic acid mixed aqueous solution, and the reaction was carried out for 60 min to obtain a Cu-MOF suspension.

[0101] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0102] Aluminum gel and Cu-MOF suspension were mixed, slurried at 60°C for 60 min, and then calcined at 350°C for 40 min to obtain methanol synthesis catalyst.

[0103] Comparative Example 3

[0104] The only difference between this comparative example and Example 1 is that the preparation method of the methanol synthesis catalyst is as follows:

[0105] A zinc salt-nicotinic acid mixed aqueous solution with a zinc nitrate concentration of 1.5 mol / L and a nicotinic acid concentration of 2 mol / L was prepared.

[0106] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a zinc salt-nicotinic acid mixed aqueous solution, and the reaction was carried out for 60 min to obtain a Zn-MOF suspension.

[0107] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0108] Aluminum gel was mixed with Zn-MOF suspension, slurried at 60°C for 60 min, and then calcined at 350°C for 40 min to obtain methanol synthesis catalyst.

[0109] Comparative Example 4

[0110] The only difference between this comparative example and Example 1 is that the methanol synthesis catalyst was prepared by the following steps:

[0111] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 1 mol / L nicotinic acid was prepared.

[0112] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF suspension.

[0113] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0114] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60°C for 60 min, and then calcined at 350°C for 40 min to obtain methanol synthesis catalyst.

[0115] Comparative Example 5

[0116] The only difference between this comparative example and Example 1 is that the methanol synthesis catalyst was prepared by the following steps:

[0117] A mixed aqueous solution of copper salt, zinc salt, and nicotinic acid with a concentration of 1 mol / L copper nitrate, 0.5 mol / L zinc nitrate, and 6.5 mol / L nicotinic acid was prepared.

[0118] At 20°C and under vigorous stirring, 0.3 mol of pyridine was added dropwise to 1 L of a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid, and the reaction was carried out for 60 min to obtain a Cu-Zn-MOF suspension.

[0119] 0.5 mol of aluminum nitrate was dissolved in water to obtain an aluminum nitrate solution. 1 mol / L of NH3·H2O solution was added dropwise to the solution at 60℃. The mixture was stirred until the pH of the mixed solution reached 7.0, which was the reaction endpoint. The solution was then aged for 60 min to obtain aluminum gel.

[0120] Aluminum gel was mixed with Cu-Zn-MOF suspension, slurried at 60°C for 60 min, and then calcined at 350°C for 40 min to obtain methanol synthesis catalyst.

[0121] Performance testing

[0122] Test 1: XRD characterization was performed on the Cu-Zn-MOF prepared in Comparative Example 1, the Cu-MOF prepared in Comparative Example 2, and the Zn-MOF prepared in Comparative Example 3. The obtained XRD spectra are shown below. Figure 1 As shown.

[0123] Reference Figure 1The diffraction peaks of Zn-MOF are mainly located at 2θ = 10.9°, 12.1°, 14.2°, 15.4°, 17.1°, 18.2°, 20.9°, and 23.2°, while those of Cu-MOF are mainly located at 2θ = 11.9°, 13.0°, 13.7°, 15.2°, 17.2°, 17.8°, 20.2°, 22.4°, and 24.9°. The diffraction peaks of Cu-Zn-MOF are mainly concentrated at 2θ = 11.8°, 12.8°, 13.4°, 15.3°, 16.8°, 20.1°, 22.2°, and 24.6°, which are different from the positions of the diffraction peaks of Cu-MOF and Zn-MOF. By comparing the diffraction peak positions of Cu-Zn-MOF, Cu-MOF, and Zn-MOF, it can be seen that the Cu-Zn-MOF prepared in Example 1 is not a simple physical mixture of Cu-MOF and Zn-MOF, but a novel MOF structure doped with Cu and Zn bimetals.

[0124] Test 2: Take the methanol synthesis catalyst samples prepared in Examples 1-9 and Comparative Examples 1-5, and conduct activity tests as follows:

[0125] The methanol synthesis catalyst was loaded with 4 ml and pre-reduced in a fixed-bed reactor. The reduction conditions were as follows: the temperature was programmed to rise from room temperature to 250 °C at a rate of 30 °C / h, held at 250 °C for 2 h, and a mixture of 5 vol% H2 and 95 vol% N2 was introduced under normal pressure. The introduced gas was then converted to N2, purged, and the reaction pressure was increased to 5.0 MPa. The temperature was maintained at 250 °C for 1 hour, and then converted to synthesis gas [φ(CO) 15%, φ(CO2) 4%, φ(H2) 65%, balance N2]. The reaction was then carried out at 250 °C, 5.0 MPa, and a space velocity of 10000 h⁻¹. -1 The CO adsorption effect was evaluated under the specified conditions. The initial activity of the methanol synthesis catalyst was detected, and the CO adsorption selectivity (%) and CO conversion rate (%) were recorded.

[0126] The methanol synthesis catalyst was heat-treated at 400℃ for 5 hours under normal pressure. The activity of the heat-treated methanol synthesis catalyst was then measured by the above method, and the activity decay rate was calculated. Activity decay rate = (initial activity - activity after heat treatment) / initial activity × 100%.

[0127] The results are summarized in Table 1.

[0128] Table 1

[0129]

[0130]

[0131] Combined with Examples 1-9, Comparative Example 1, and Table 1, it can be seen that the methanol synthesis catalyst prepared by the method disclosed in this application has a CO adsorption selectivity ≥97.40%, a CO conversion rate >57.6%, and a high-temperature activity decay rate ≤11.3%. It is evident that the method disclosed in this application can enable the methanol synthesis catalyst to have better selectivity and CO conversion rate compared with the common co-precipitation method, and also has good heat resistance and a lower possibility of migration and aggregation of active components at high temperatures.

[0132] Based on Examples 1-9, Comparative Examples 2-3, and Table 1, it can be seen that the methanol synthesis catalyst can only exert its best catalytic performance when Cu and Zn work synergistically. When Zn co-catalyst is lacking, the catalytic activity of the methanol synthesis catalyst decreases and the CO conversion rate is significantly reduced. When Cu active catalytic component is lacking, the methanol synthesis catalyst has no catalytic activity and cannot catalyze the normal progress of the methanol synthesis reaction.

[0133] Based on Examples 1-9, Comparative Examples 4-5, and Table 1, it can be seen that when the molar ratio of the total amount of copper-zinc salt to nicotinic acid is too large, the high-temperature activity degradation rate of a unit amount of methanol synthesis catalyst increases, the heat resistance activity of the methanol synthesis catalyst decreases, and the CO conversion rate decreases to a certain extent. This may be due to the decreased dispersibility of the copper and zinc active components, which affects the catalytic activity and makes the metal active components more prone to agglomeration at high temperatures. Conversely, when the molar ratio of the total amount of copper-zinc salt to nicotinic acid is too small, the catalytic activity of a unit amount of methanol synthesis catalyst decreases, and the catalyst's CO adsorption and CO conversion rate decrease.

[0134] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for producing a methanol synthesis catalyst having high selectivity for adsorbing CO, characterized by, Includes the following steps: Pyridine was added dropwise to a mixed aqueous solution of copper salt, zinc salt, and nicotinic acid at 10-40℃, and the reaction was carried out for 30-90 min to obtain a copper-zinc metal-organic framework suspension; the molar ratio of the total amount of copper salt and zinc salt to nicotinic acid in the mixed aqueous solution of copper salt, zinc salt, and nicotinic acid was 1:(1-3); Aluminum salts are reacted with alkali to obtain aluminum glue; Aluminum gel and copper-zinc metal-organic framework suspension were mixed and slurried, and then calcined to obtain a methanol synthesis catalyst with high selective adsorption of CO.

2. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 1, characterized in that, In the copper-zinc-nicotinic acid mixed aqueous solution, the molar ratio of copper ions to zinc ions is (3-1):

1.

3. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 2, characterized in that, In the copper-zinc-nicotinic acid mixed aqueous solution, the concentration of copper salt is 0.1-3 mol / L, the concentration of zinc salt is 0.1-1 mol / L, and the concentration of nicotinic acid is 0.1-3 mol / L.

4. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 1, characterized in that, The molar ratio of nicotinic acid to pyridine in the copper-zinc-nicotinic acid mixed aqueous solution is (10-50):

1.

5. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 4, characterized in that, The aluminum, copper, and zinc salts contain the same type of anion, selected from nitrate, acetate, and oxalate ions.

6. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 1, characterized in that, Specifically, it includes: At 30-60℃, alkali is added dropwise to the aluminum salt solution to carry out the reaction. When the pH of the solution reaches 7.0-9.0, the reaction reaches its endpoint. Then, the solution is aged for 30-90 minutes to obtain aluminum gel.

7. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 1, characterized in that, The molar ratio of the aluminum salt to the total amount of copper and zinc salts in the copper-zinc-nicotinic acid mixed aqueous solution is 1:(1-6).

8. The method for preparing the methanol synthesis catalyst with high selective CO adsorption according to claim 1, characterized in that, The alkali is selected from one of NaOH, NH3·H2O, NaHCO3, and Na2CO3.

9. As described in claim 1, characterized in that, The processing temperature of the mixing and pulping step is 30-60℃, and the pulping time is 30-90min; the roasting temperature of the roasting step is 300-400℃, and the roasting time is 30-60min.

10. A methanol synthesis catalyst with high selectivity for CO adsorption, characterized in that, It is prepared by the method for preparing the methanol synthesis catalyst with high selective adsorption of CO as described in any one of claims 1-9.

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