A Na2S-modified copper-based catalyst and its preparation method, and methanol preparation method
By forming a stable copper sulfide phase and electron transfer effect on the surface of the copper-based catalyst, the problem of copper-based catalysts being susceptible to sulfide poisoning is solved, and the sulfur resistance of the catalyst is improved and the service life is extended.
Patent Information
- Application Number
- CN202510992589.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2045-07-18
AI Technical Summary
Existing copper-based catalysts are easily poisoned by sulfides and deactivated, and traditional desulfurization processes are costly, affecting the life and stability of the catalyst.
Na2S is used to modify the copper-based catalyst. By forming a stable copper sulfide phase on the surface of the copper-based catalyst, the sulfur molecules are blocked from contacting the active sites. The catalyst surface environment is adjusted through the electron transfer effect and alkalinity, sulfur poisoning is inhibited, and the catalyst life is extended.
The sulfur resistance of the catalyst is improved, the service life is extended, the growth of the copper active center grains is slowed down, and the stability of the catalyst is improved.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of catalyst preparation, and in particular to a Na2S-modified copper-based catalyst and a preparation method thereof, and a methanol preparation method. Background Art
[0002] Methanol, also known as hydroxymethane, is an organic compound and the simplest saturated monohydric alcohol. At room temperature and pressure, it is a colorless gas with a pungent odor and is readily soluble in water. Industrial methanol has a wide range of uses. In addition to being a good solvent for many organic compounds, it is primarily used in the industrial production of synthetic fibers, formaldehyde, plastics, pharmaceuticals, pesticides, dyes, and protein synthesis, serving as a fundamental organic chemical raw material. Methanol is almost exclusively synthesized industrially through the pressurized catalytic hydrogenation of carbon monoxide and carbon dioxide. The typical process includes feed gas production, feed gas purification, methanol synthesis, and crude methanol distillation. Many catalysts used in methanol production, such as natural gas and naphtha steam reforming catalysts and copper-zinc-aluminum-magnesium catalysts, are susceptible to sulfide poisoning and inactivation. Therefore, sulfide removal is essential, requiring high-cost and demanding desulfurization processes. Summary of the Invention
[0003] In order to solve the above problems, the present invention provides a Na2S-modified copper-based catalyst and a preparation method thereof, and a methanol preparation method. The catalyst is prepared by the Na2S modification method, which can improve the sulfur resistance of the catalyst and extend the service life of the catalyst. In addition, Na2S on the catalyst surface can slow down the growth of copper grains in the active center and improve the stability of the catalyst.
[0004] The present invention provides a Na2S-modified copper-based catalyst, comprising: adding a calcined copper-based catalyst to a Na2S solution and modifying the catalyst to obtain a reactant; the copper-based catalyst is a mixture of copper, zinc, aluminum and magnesium oxides, the mass proportion of the Na2S is 0.1%-1%, and the mass proportion of the copper-based catalyst is 99%-99.9%.
[0005] The present invention also provides a preparation method of the Na2S-modified copper-based catalyst as described above, comprising the following steps: preparing solution A: adding a precursor of a copper-zinc-aluminum-magnesium mixture to deionized water, and after fully dissolving, recording it as solution A; preparing solution B: dissolving sodium carbonate in deionized water, and after fully dissolving, recording it as solution B; dropping the solution A and the solution B in parallel, and controlling the dropping time of the solution A and the solution B, as well as the pH value of the solution, to obtain a slurry containing a precipitate; allowing the slurry to stand for aging, filtering, washing, drying and calcining to obtain a CuZnAlMg catalyst; preparing a Na2S aqueous solution: dissolving Na2S in water to obtain a Na2S aqueous solution; placing the CuZnAlMg catalyst in the Na2S aqueous solution by an equal volume impregnation method, and vacuum drying to obtain a Na2S-modified CuZnAlMg catalyst.
[0006] In one embodiment of the present invention, the precursor of the copper-zinc-aluminum-magnesium mixture includes: one or more of copper nitrate, copper sulfate and copper chloride containing copper, one or more of zinc nitrate, zinc sulfate and zinc chloride containing zinc, one or more of aluminum nitrate, aluminum sulfate and aluminum chloride containing aluminum, and one or more of magnesium nitrate, magnesium sulfate and magnesium chloride containing magnesium.
[0007] In one embodiment of the present invention, the time for the co-current addition of the solution A and the solution B is 0.5-2 h and 0.5-2 h respectively.
[0008] In one embodiment of the present invention, the pH value of the solution is controlled to be 7-9.
[0009] In one embodiment of the present invention, the aging time of the slurry during static aging is 0.5-2h, and the aging temperature is 50-80°C; the drying temperature during the drying process is 80-150°C, and the drying time is 4-12h; the roasting temperature during the roasting process is 350-500°C, the roasting time is 3-6h, and the heating rate is 1°C / min.
[0010] In one embodiment of the present invention, the drying temperature during the vacuum drying process is 40-60°C.
[0011] In one embodiment of the present invention, the mass proportions of copper, zinc, aluminum and magnesium in the Na2S-modified CuZnAlMg catalyst as oxides are: 50%-60%; 20%-30%; 10%-20%; 1%-5%.
[0012] The present invention also provides a method for preparing methanol, comprising the following steps: placing a catalyst into a reactor; -1 The reducing gas was introduced into the reactor at a space velocity of 10000 h to react, wherein the reducing gas was a mixture of H2 and Ar;-1 The reaction gas is introduced at an air velocity of 1000 nm to carry out the reaction, wherein the reaction gas is a mixed gas of H2S, H2 and CO2, and methanol is obtained after the reaction is completed; the catalyst is the Na2S modified copper-based catalyst as described above, or the Na2S modified copper-based catalyst obtained according to the preparation method as described above.
[0013] In one embodiment of the present invention, the volume proportion of the reducing gas is 5%, and the reduction is carried out at 250°C for 2h; the volume proportion of the reaction gas is 0.05%, and H2 / CO2=3, and the reaction is carried out at a pressure of 5.0MPa and a reaction temperature of 250°C.
[0014] Compared with the existing technology, the present invention has the following beneficial technical effects:
[0015] The present invention provides a Na2S-modified copper-based catalyst, a preparation method thereof, and a methanol production method. These catalysts can overcome the problem of gradual deactivation of copper-based catalysts caused by trace amounts of sulfur in the feed gas. The Na2S-modified catalyst is presulfurized on the surface of the copper-based catalyst, significantly improving the catalyst's sulfur resistance and thus extending its service life. Furthermore, the Na2S on the catalyst surface can slow the growth of copper grains in the copper active centers, improving the catalyst's stability. The Na2S-modified copper-based catalyst provided by the present invention can be used in the carbon dioxide hydrogenation to methanol reaction and exhibits superior sulfur resistance compared to conventional catalysts. DETAILED DESCRIPTION
[0016] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.
[0017] The present invention provides a Na2S-modified copper-based catalyst, comprising: adding a calcined copper-based catalyst to a Na2S solution, and modifying the catalyst to obtain a reactant; the copper-based catalyst is a mixture of copper, zinc, aluminum, and magnesium oxides, wherein the mass proportion of Na2S is 0.1%-1%, and the mass proportion of the copper-based catalyst is 99%-99.9%.
[0018] As a sulfiding agent, Na2S reacts with copper-based materials during catalyst preparation or pretreatment to form a stable copper sulfide phase (such as Cu2S or CuS). These sulfide phases have low surface energy and weak adsorption capacity for sulfur species (such as H2S, SO2, etc.), which can effectively block sulfur molecules from directly contacting the active sites of the catalyst, avoiding the formation of irreversible metal-sulfur bonds (such as strong adsorption state of Cu-S), thereby inhibiting sulfur poisoning. + The introduction of sodium changes the electron density of the copper active site through the electron transfer effect. As an alkali metal, sodium provides electrons to copper, increasing the electron cloud density on the copper surface and weakening the sulfur species (such as S 2- , HS- ) (because the adsorption of sulfur depends on the electron deficiency of the metal site). The alkalinity of sodium can neutralize the acidic sulfur species (such as H2S) in the reaction system, reduce its dissociative adsorption, and at the same time adjust the acid-base environment on the catalyst surface to inhibit the existence of sulfur in a strongly adsorbed state (such as bridge or bidentate sulfate). The modified catalyst surface can promote the redox cycle of sulfur species or convert them into inert forms. The copper sulfide phase has certain redox properties and can convert adsorbed sulfur species (such as S 0 、S 2- ) is oxidized to SO4 2- The latter exists in a weakly adsorbed state or is stabilized by the basic sites of the support (such as Al2O3), avoiding clogging the active centers. Therefore, the catalyst prepared using the Na2S modification method of the present invention can improve the catalyst's sulfur tolerance and extend its service life. Furthermore, the Na2S on the catalyst surface can slow the growth of copper grains in the copper active centers, improving the catalyst's stability.
[0019] The present invention also provides a method for preparing the Na2S-modified copper-based catalyst, comprising the following steps:
[0020] Preparation of Solution A: Adding a precursor of a copper-zinc-aluminum-magnesium mixture to deionized water, and after fully dissolving, this is referred to as Solution A. Preparation of Solution B: Dissolving sodium carbonate in deionized water, and after fully dissolving, this is referred to as Solution B. Adding Solution A and Solution B dropwise in parallel, while controlling the addition time of Solution A and Solution B and the pH value of the solutions, yields a slurry containing a precipitate. The slurry is then allowed to stand for aging, filtered, washed, dried, and calcined to yield a CuZnAlMg catalyst. Preparation of a Na2S aqueous solution: Dissolving Na2S in water to yield a Na2S aqueous solution. The CuZnAlMg catalyst is then placed in the Na2S aqueous solution by an equal volume impregnation method, and vacuum dried to yield a Na2S-modified CuZnAlMg catalyst. The equal volume impregnation method allows the Na2S solution to uniformly fill the catalyst pores. During subsequent treatments such as drying and calcination, the Na2S component can strongly interact with the copper in the catalyst, thereby yielding a presulfided catalyst with a highly dispersed Na2S component.
[0021] In one embodiment of the present invention, the precursor of the copper-zinc-aluminum-magnesium mixture includes: one or more of copper nitrate, copper sulfate and copper chloride containing copper, one or more of zinc nitrate, zinc sulfate and zinc chloride containing zinc, one or more of aluminum nitrate, aluminum sulfate and aluminum chloride containing aluminum, and one or more of magnesium nitrate, magnesium sulfate and magnesium chloride containing magnesium.
[0022] In one embodiment of the present invention, the time for concurrently adding solution A and solution B is 0.5-2 h and 0.5-2 h, respectively, for example, 0.5 h, 1 h, 1.5 h, 2 h.
[0023] In one embodiment of the present invention, the pH value of the solution is controlled to be 7-9, for example, pH=7, pH=7.5, pH=8, pH=8.5, pH=9.
[0024] In one embodiment of the present invention, the aging time during the static aging process of the slurry is 0.5-2h, for example, 0.5h, 1h, 2h, and the aging temperature is 50-80°C, for example, 50°C, 60°C, 70°C, 80°C; the drying temperature during the drying process is 80-150°C, for example, 80°C, 100°C, 120°C, 150°C, and the drying time is 4-12h, for example, 4h, 6h, 8h, 12h; the roasting temperature during the roasting process is 350-500°C, for example, 350°C, 400°C, 450°C, 500°C, the roasting time is 3-6h, for example, 3h, 4h, 5h, 6h, and the heating rate is 1°C / min.
[0025] In one embodiment of the present invention, the drying temperature during the vacuum drying process is 40-60°C, for example, 40°C, 50°C, or 60°C.
[0026] In one embodiment of the present invention, the mass proportions of copper, zinc, aluminum and magnesium in the Na2S-modified CuZnAlMg catalyst as oxides are: 50%-60%; 20%-30%; 10%-20%; 1%-5%, for example, 50%, 30%, 15% and 5% respectively. It should be noted that the mass of Na2S is not included.
[0027] The present invention also provides a method for preparing methanol, comprising the following steps:
[0028] The prepared catalyst is loaded into the reactor. The catalyst is the Na2S modified copper-based catalyst as described above, or the Na2S modified copper-based catalyst obtained according to the preparation method as described above. Then, the catalyst is heated for 2000 h. -1 The reducing gas was a mixture of H2 and Ar, with a volume ratio of 5%, and the mixture was reduced at 250 °C for 2 h. After cooling to room temperature, the mixture was heated for 10,000 h. -1 The reaction gas is introduced at an air velocity of , and the reaction gas is a mixed gas of H2S, H2 and CO2. The volume proportion of the reaction gas is 0.05%, and H2 / CO2=3. The carbon dioxide hydrogenation to methanol reaction is carried out at a pressure of 5.0 MPa and a reaction temperature of 250°C.
[0029] The present invention will be further described below with reference to the embodiments.
[0030] Example 1
[0031] Add copper, zinc, aluminum and magnesium salt solution (the mass proportion of oxide is 50%, 30%, 15% and 5% respectively, with a total mass of 99g) into 500g of deionized water and record it as solution A after it is fully dissolved; dissolve 160g of sodium carbonate in 500g of deionized water to obtain solution B; add solution A and solution B dropwise in parallel, and control the addition time of solution A and solution B to be the same at 0.5h, maintain the pH value at 7, and obtain a slurry containing a precipitate; let the slurry stand at 60℃ for aging for 2h, filter and wash. After drying at 150℃ for 4h, calcine at 350℃ for 6h with a heating rate of 1℃ / min to obtain a copper, zinc, aluminum and magnesium catalyst without Na2S modification;
[0032] Dissolve 1.0g of Na2S in 10ml of deionized water. Use the equal volume impregnation method to take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above Na2S solution. Dry it in a vacuum at 40°C to obtain a 1wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0033] 1.0 g of the above Na2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0034] Example 2
[0035] The copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 60%, 25%, 10%, and 5%, respectively, with a total mass of 99.9g) was added to 500g of deionized water and recorded as solution A after being fully dissolved; 160g of sodium carbonate was dissolved in 500g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, while the addition time of solution A and solution B was controlled to be the same for 2h, and the pH value was maintained at 9 to obtain a slurry containing a precipitate; the slurry was aged at 80℃ for 0.5h, filtered, and washed. After drying at 80℃ for 12h, it was calcined at 500℃ for 3h with a heating rate of 1℃ / min to obtain a copper-zinc-aluminum-magnesium catalyst without Na2S modification;
[0036] Dissolve 0.1g Na2S in 10ml deionized water. Using the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above Na2S solution. Dry it in a vacuum at 60°C to obtain a 0.1wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0037] 1.0 g of the above Na2S-modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0038] Example 3
[0039] The copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 60%, 20%, 19%, and 1%, respectively, with a total mass of 99.5g) was added to 500g of deionized water and recorded as solution A after being fully dissolved; 160g of sodium carbonate was dissolved in 500g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same for 1h, while maintaining the pH value at 8 to obtain a slurry containing a precipitate; the slurry was allowed to stand at 60°C for 1h, filtered, and washed. After drying at 100°C for 8h, it was calcined at 400°C for 4h with a heating rate of 1°C / min to obtain a copper-zinc-aluminum-magnesium catalyst without Na2S modification;
[0040] Dissolve 0.5g Na2S in 10ml deionized water. Use the equal volume impregnation method to take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above Na2S solution. Dry it in a vacuum at 60°C to obtain a 0.5wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0041] 1.0 g of the above Na2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0042] Example 4
[0043] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 52%, 25%, 20%, and 3%, respectively, with a total mass of 99.7g) was added to 500g of deionized water and recorded as solution A after being fully dissolved; 160g of sodium carbonate was dissolved in 500g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same for 1.5h, while maintaining the pH value at 8.5 to obtain a slurry containing a precipitate; the slurry was allowed to stand and age at 70°C for 1.5h, filtered, and washed. After drying at 120°C for 6h, it was calcined at 450°C for 5h with a heating rate of 1°C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified with Na2S;
[0044] Dissolve 0.3g Na2S in 10ml deionized water, use the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above solution, and vacuum dry it at 60°C to obtain a 0.3wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0045] 1.0 g of the above Na2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0046] Example 5
[0047] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 55%, 28%, 15%, and 2%, respectively, with a total mass of 99.2g) was added to 500g of deionized water and recorded as solution A after being fully dissolved; 160g of sodium carbonate was dissolved in 500g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same at 0.8h, while maintaining the pH value at 7.5 to obtain a slurry containing a precipitate; the slurry was aged at 60°C for 1.8h, filtered, and washed. After drying at 90°C for 10h, it was calcined at 450°C for 3h with a heating rate of 1°C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified with Na2S;
[0048] Dissolve 0.8g Na2S in 10ml deionized water, use the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above solution, and vacuum dry it at 60°C to obtain a 0.8wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0049] 1.0 g of the above Na2S-modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0050] Example 6
[0051] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 57%, 26%, 13%, and 4%, respectively, with a total mass of 99.6g) was added to 500g of deionized water and recorded as solution A after being fully dissolved; 160g of sodium carbonate was dissolved in 500g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same at 1.2h, while maintaining the pH value at 8.5 to obtain a slurry containing a precipitate; the slurry was allowed to stand at 75°C for 1.2h, filtered, and washed. After drying at 130°C for 8h, it was calcined at 400°C for 5h with a heating rate of 1°C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified by Na2S.
[0052] Dissolve 0.4g Na2S in 10ml deionized water, use the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with Na2S and place it in the above solution, and vacuum dry it at 55°C to obtain a 0.4wt% Na2S-modified copper-zinc-aluminum-magnesium catalyst.
[0053] 1.0 g of the above Na2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0054] Comparative Example 1
[0055] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 60%, 25%, 10%, and 5%, respectively, with a total mass of 99.9 g) was added to 500 g of deionized water and recorded as solution A after being fully dissolved; 160 g of sodium carbonate was dissolved in 500 g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same for 2 h, while maintaining the pH value at 9 to obtain a slurry containing a precipitate; the slurry was allowed to stand and age at 80 ° C for 0.5 h, filtered, and washed. After drying at 80 ° C for 12 h, it was calcined at 500 ° C for 3 h with a heating rate of 1 ° C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified by Na2S;
[0056] 1.0 g of the above Na2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0057] Comparative Example 2
[0058] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 60%, 25%, 10%, and 5%, respectively, with a total mass of 99.0 g) was added to 500 g of deionized water and recorded as solution A after being fully dissolved; 160 g of sodium carbonate was dissolved in 500 g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same for 2 h, while maintaining the pH value at 9 to obtain a slurry containing a precipitate; the slurry was allowed to stand and age at 80 ° C for 0.5 h, filtered, and washed. After drying at 80 ° C for 12 h, it was calcined at 500 ° C for 3 h with a heating rate of 1 ° C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified by K2S;
[0059] Dissolve 1.0g K2S in 10ml deionized water, use the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with K2S and place it in the above solution, and vacuum dry it at 55°C to obtain a 1.0wt% K2S-modified copper-zinc-aluminum-magnesium catalyst.
[0060] 1.0 g of the above K2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0061] Comparative Example 3
[0062] A copper-zinc-aluminum-magnesium salt solution (the mass proportions of the oxides are 60%, 25%, 10%, and 5%, respectively, with a total mass of 99.0 g) was added to 500 g of deionized water and recorded as solution A after being fully dissolved; 160 g of sodium carbonate was dissolved in 500 g of deionized water to obtain solution B; solution A and solution B were added dropwise in parallel, and the addition time of solution A and solution B was controlled to be the same for 2 h, while maintaining the pH value at 9 to obtain a slurry containing a precipitate; the slurry was allowed to stand and age at 80 ° C for 0.5 h, filtered, and washed. After drying at 80 ° C for 12 h, it was calcined at 500 ° C for 3 h with a heating rate of 1 ° C / min to obtain a copper-zinc-aluminum-magnesium catalyst that was not modified with (NH4)2S;
[0063] Dissolve 1.0g (NH4)2S in 10ml deionized water. Using the equal volume impregnation method, take an appropriate amount of copper-zinc-aluminum-magnesium catalyst powder that has not been modified with (NH4)2S and place it in the above solution. Dry it in a vacuum at 55°C to obtain a 1.0wt% (NH4)2S-modified copper-zinc-aluminum-magnesium catalyst.
[0064] 1.0 g of the above (NH4)2S modified copper-zinc-aluminum-magnesium catalyst was loaded into the reactor and heated for 2000 h. -1 A mixture of H2 and Ar was introduced, with a volume fraction of 5%, and the reduction was carried out at 250°C for 2 hours. After cooling to room temperature, the mixture was heated for 10,000 hours. -1 The reaction gas containing 0.05% by volume is introduced at an air velocity of 1.5, wherein the reaction gas is a mixed gas of H2S, H2, and CO2, wherein H2 / CO2=3, the pressure is 5.0 MPa, and the reaction temperature is 250°C for the hydrogenation of carbon dioxide to produce methanol.
[0065] The activity of the catalysts in Examples 1-6 and Comparative Examples 1-3 was tested. The test results are shown in Table 1.
[0066] Table 1 Activity performance of catalysts in Examples 1-6 and Comparative Examples 1-3
[0067]
[0068] As can be seen from Table 1, by comparing Examples 1-6 with Comparative Example 1, it can be concluded that the sulfur resistance of the copper-zinc-aluminum-magnesium catalyst modified with Na2S is significantly better than that of the copper-zinc-aluminum-magnesium catalyst not modified with Na2S. The copper-zinc-aluminum-magnesium catalyst not modified with Na2S is deactivated after 18 hours of reaction, while the copper-zinc-aluminum-magnesium catalyst modified with different contents of Na2S is completely deactivated in 30-50 hours. It can be seen that the use of the Na2S modification method to prepare the copper-zinc-aluminum-magnesium catalyst can improve the sulfur resistance of the copper-zinc-aluminum-magnesium catalyst and extend the service life of the copper-zinc-aluminum-magnesium catalyst;
[0069] By comparing Comparative Example 2-3 with Comparative Example 1, it can be concluded that the sulfur resistance of the copper-zinc-aluminum-magnesium catalyst modified with K2S and (NH4)2S is significantly better than that of the copper-zinc-aluminum-magnesium catalyst not modified with K2S and (NH4)2S. The copper-zinc-aluminum-magnesium catalyst not modified with K2S and (NH4)2S is deactivated after 18 hours of reaction, while the copper-zinc-aluminum-magnesium catalyst modified with different contents of K2S and (NH4)2S is completely deactivated at 28 hours and 20 hours respectively. However, by comparing Example 1 with Comparative Example 2-3, it can be concluded that the copper-zinc-aluminum-magnesium catalyst modified with the same mass proportion of Na2S, K2S and (NH4)2S is completely deactivated at 28 hours and 20 hours respectively. The copper-zinc-aluminum-magnesium catalysts were modified, and it was obvious that the sulfur resistance of the copper-zinc-aluminum-magnesium catalyst modified with Na2S was significantly better than that of the copper-zinc-aluminum-magnesium catalyst modified with K2S and (NH4)2S. The copper-zinc-aluminum-magnesium catalyst modified with 1.0% by mass of Na2S was completely deactivated within 30 hours, while the copper-zinc-aluminum-magnesium catalyst modified with 1.0% by mass of K2S and (NH4)2S was completely deactivated within 28 hours and 20 hours respectively. Therefore, although the sulfur resistance of the copper-zinc-aluminum-magnesium catalyst modified with K2S and (NH4)2S was improved, the improvement effect was not as good as that of modification with Na2S.
[0070] As can be seen from the above description, the Na2S-modified copper-based catalyst and its preparation method, as well as the methanol preparation method provided by the present invention, can overcome the problem of gradual deactivation of the copper-based catalyst caused by trace sulfur in the feed gas. The Na2S-modified catalyst is pre-sulfurized on the surface of the copper-based catalyst, greatly improving the catalyst's sulfur resistance, thereby extending the catalyst's service life. In addition, Na2S on the catalyst surface can slow the growth of copper grains in the copper active center, thereby improving the stability of the catalyst. The Na2S-modified copper-based catalyst provided by the present invention can be used in the carbon dioxide hydrogenation to methanol reaction and has excellent sulfur resistance compared to traditional catalysts.
[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A Na2S modified copper-based catalyst, characterized in that The method comprises adding a calcined copper-based catalyst to a Na2S solution and modifying the reaction product; the copper-based catalyst is a mixture of copper, zinc, aluminum and magnesium oxides, the mass proportion of the Na2S is 0.1%-1%, and the mass proportion of the copper-based catalyst is 99%-99.9%; The copper-based catalyst is prepared by the following preparation method, which comprises: Prepare solution A: add the precursor of the copper-zinc-aluminum-magnesium mixture into deionized water and record it as solution A after it is fully dissolved; Prepare solution B: dissolve sodium carbonate in deionized water and record it as solution B after it is fully dissolved; Adding the solution A and the solution B dropwise in parallel, while controlling the addition time of the solution A and the solution B, as well as the pH value of the solution, to obtain a slurry containing a precipitate; The slurry is allowed to stand for aging, filtered, washed, dried and calcined to obtain a CuZnAlMg catalyst.
2. A method for preparing a Na2S-modified copper-based catalyst as claimed in claim 1, characterized in that: The steps include: Prepare solution A: add the precursor of the copper-zinc-aluminum-magnesium mixture into deionized water and record it as solution A after it is fully dissolved; Prepare solution B: dissolve sodium carbonate in deionized water and record it as solution B after it is fully dissolved; Adding the solution A and the solution B dropwise in parallel, while controlling the addition time of the solution A and the solution B, as well as the pH value of the solution, to obtain a slurry containing a precipitate; The slurry is allowed to stand for aging, filtered, washed, dried and calcined to obtain a CuZnAlMg catalyst; Preparation of Na2S aqueous solution: dissolve Na2S in water to obtain Na2S aqueous solution; The CuZnAlMg catalyst is placed in the Na2S aqueous solution by an equal volume impregnation method, and the Na2S-modified CuZnAlMg catalyst is obtained after vacuum drying.
3. The preparation method according to claim 2, characterized in that The precursor of the copper-zinc-aluminum-magnesium mixture includes: one or more of copper nitrate, copper sulfate and copper chloride containing copper, one or more of zinc nitrate, zinc sulfate and zinc chloride containing zinc, one or more of aluminum nitrate, aluminum sulfate and aluminum chloride containing aluminum, and one or more of magnesium nitrate, magnesium sulfate and magnesium chloride containing magnesium.
4. The preparation method according to claim 2, characterized in that The time for concurrently adding the solution A and the solution B is 0.5-2 h and 0.5-2 h respectively.
5. The preparation method according to claim 2, characterized in that The pH value of the solution is controlled to be 7-9.
6. The preparation method according to claim 2, characterized in that During the static aging process of the slurry, the aging time is 0.5-2 hours and the aging temperature is 50-80°C; during the drying process, the drying temperature is 80-150°C and the drying time is 4-12 hours; during the roasting process, the roasting temperature is 350-500°C, the roasting time is 3-6 hours, and the heating rate is 1°C / min.
7. The preparation method according to claim 2, characterized in that The drying temperature during the vacuum drying process is 40-60°C.
8. The preparation method according to claim 2, characterized in that The mass proportions of copper, zinc, aluminum and magnesium in the Na2S-modified CuZnAlMg catalyst as oxides are: 50%-60%; 20%-30%; 10%-20%; 1%-5%.
9. A method for preparing methanol, characterized in that: The steps include: loading the catalyst into the reactor; 2000h -1 The reducing gas is introduced at a space velocity of , wherein the reducing gas is a mixed gas of H2 and Ar; 10000h -1 The reaction gas is introduced at a space velocity of , wherein the reaction gas is a mixture of H2S, H2 and CO2; Methanol is obtained after the reaction is completed; The catalyst is the Na2S-modified copper-based catalyst according to claim 1, or the Na2S-modified copper-based catalyst obtained by the preparation method according to any one of claims 2 to 8.
10. The method for preparing methanol according to claim 9, characterized in that: The volume proportion of the reducing gas is 5%, and the reduction is carried out at 250°C for 2h; the volume proportion of the reaction gas is 0.05%, and H2 / CO2=3, and the reaction is carried out at a pressure of 5.0MPa and a reaction temperature of 250°C.