Full-methanation catalyst and method for making same

Abstract

The application discloses a full methanation catalyst and a preparation method thereof. The catalyst comprises a carrier Al2O3, an active component Ni, a first additive, a second additive and a third additive. The catalyst comprises the following components in percentage by mass: the Ni is 3-60%, the first additive is 2-30%, the second additive is 0.5-30%, the third additive is 1-5%, and the balance is the carrier Al2O3. Compared with the prior art, the catalyst has a centimeter strength of more than 1000 N, good activity, high stability and high activity, and can meet the harsh working condition requirements of a first-stage reactor of a large full methanation process device. The catalyst can maintain good catalytic performance in a wide temperature range, prolong the service life of the catalyst, effectively inhibit the occurrence of side reactions such as CO disproportionation and high-temperature cracking of methane, and reduce the carbon deposition and pulverization.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a fully methanated catalyst and its preparation method. Background Technology

[0002] Energy Demand and Resource Utilization: With the continuous rise in global energy demand and increasing environmental awareness, finding clean and efficient energy alternatives has become an urgent priority. Natural gas, as a relatively clean energy source, is experiencing a sustained increase in demand. However, traditional natural gas resources are limited, making the conversion of other resources into natural gas through chemical conversion methods a research hotspot. Full methanation technology can convert syngas (mainly composed of CO and H2) produced from coal gasification into methane, thereby producing high-value products such as synthetic natural gas (SNG), providing a new pathway for natural gas production. This is of great significance for alleviating the natural gas shortage problem. Simultaneously, this technology also helps improve the comprehensive utilization efficiency of resources such as coal, maximizing resource utilization, reducing dependence on traditional energy sources, promoting the optimization and upgrading of the energy structure, and ensuring the security and stability of energy supply.

[0003] Methanation Reaction Principles and Challenges: Methanation is an important hydrogenation reaction, with reaction equations: CO + 3H₂ → CH₄ + H₂O and CO₂ + 4H₂ → CH₄ + 2H₂O. This reaction is strongly exothermic, releasing a large amount of heat during the process, causing a sharp rise in the reaction system temperature. The adiabatic temperature rise of the gases produced by converting 1% of carbon monoxide and carbon dioxide is 72°C and 60°C, respectively. This strong exothermic characteristic makes the reaction process difficult to control and easily leads to a series of problems. For example, excessively high temperatures may cause catalyst deactivation, reactor material damage, and may also trigger unnecessary side reactions, such as carbon monoxide dismutation and high-temperature methane cracking. These side reactions not only reduce methane yield but also lead to severe carbon deposition and pulverization, affecting catalyst performance and lifespan. Therefore, effectively controlling the reaction temperature and improving catalyst activity and stability are among the key challenges to achieving the industrial application of complete methanation technology.

[0004] The shortcomings of existing technologies: The methanation catalysts used in current full methanation technologies have short lifespans, especially in the first-stage reactor. After a period of operation, carbon buildup necessitates short-term shutdowns for catalyst replacement. Therefore, developing a full methanation catalyst with long lifespan, high activity, high stability, and good low-temperature activity, along with a corresponding process method, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] This invention provides a fully methanation catalyst and its preparation method. The catalyst has high strength, good resistance to carbon buildup and pulverization, and is particularly suitable for use in the first-stage methanation reactor of a coal-to-natural gas production plant.

[0006] To achieve this technical objective, the present invention adopts the following solution: This invention provides a method for preparing a fully methanation catalyst, comprising the following steps: S1. Mix the active component, the first auxiliary agent, and the precursor of the second auxiliary agent and dissolve them in deionized water to obtain solution I; S2. Dissolve the precipitant in deionized water to prepare solutions II and III of different concentrations. S3. After calcining the precursor of the carrier at 900~1300℃ for 3~8 hours, add it to deionized water to prepare solution IV; S4. Add solution I to solution II to induce precipitation, resulting in precipitation system I; add solution III to solution IV to induce precipitation, resulting in precipitation system II. S5. Mix precipitation system I and precipitation system II, stir for 0.5 to 10 hours, and let stand for 0.5 to 10 hours. S6. The mixed precipitate system is filtered, dried, and the precursor of the third auxiliary agent is added. The mixture is then calcined and shaped to produce a fully methanated catalyst. The fully methanated catalyst prepared according to the above method comprises an active component Ni accounting for 3-60% of the total mass of the catalyst based on elemental metal, a first promoter accounting for 2-30% of the total mass of the catalyst based on oxides, a second promoter accounting for 0.5-30% of the total mass of the catalyst based on oxides, a third promoter accounting for 1-5% of the total mass of the catalyst based on oxides, and the balance being a support Al2O3; the first promoter is selected from one or more of La2O3, CeO2, Pr2O3, and Sm2O3, the second promoter is selected from one or more of Fe2O3, TiO2, CuO, ZnO, MoO3, Co3O4, ZrO2, Cr2O3, CaO, SrO, and BaO, and the third promoter is selected from K2O or MgO.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: High strength: The full methanation catalyst provided by this invention has a centimeter strength of over 1000N and good activity, meeting the harsh operating requirements of the first-stage reactor of a large-scale full methanation process unit.

[0008] High stability: The fully methanation catalyst provided by this invention has the characteristics of high stability and high activity. It can maintain good catalytic performance over a wide temperature range, extend the service life of the catalyst, and increase the effective operating time of the entire production unit.

[0009] Reduce carbon buildup and pulverization: The fully methanation catalyst provided by this invention can effectively suppress side reactions such as carbon monoxide dismutation and high-temperature methane cracking, reduce carbon buildup and pulverization, and ensure the smooth progress of the methanation reaction and the long-term operation of the equipment.

[0010] Furthermore, in steps S1 to S3, the temperature of the deionized water used to prepare the solution is 40–90°C, the molar concentration ratio of solution I to solution II is 1:1.0–5.0, and the molar concentration ratio of solution III to solution IV is 1:1.0–5.0.

[0011] Furthermore, in step S4, during the preparation of precipitate system I, the volume ratio of solution I to solution II is 1:1.5 to 4.5, preferably 1:3 to 4.

[0012] Furthermore, in step S4, during the preparation of precipitation system II, the volume ratio of solution IV to solution III is 1:3 to 9, preferably 1:4.5 to 6.

[0013] Furthermore, in step S5, the volume ratio of precipitation system I to precipitation system II is 1:0.1 to 14.8, preferably 1:0.4 to 6.

[0014] Further, step S6 specifically includes: washing, filtering, and drying the mixed precipitate system; adding one or more of the precursors of the nano-scale third auxiliary agent, such as K2CO3, MgCO3, CaCO3, K2O, MgO, and CaO, after drying; calcining to obtain the raw powder; adding calcium aluminate to the raw powder; and then adding graphite or cellulose. After mixing evenly, the mixture is pressed into tablets to obtain the finished catalyst product.

[0015] Furthermore, the drying temperature is 70~110℃, the calcination temperature is 250~700℃, and the calcination time is 2~10 hours; the amount of calcium aluminate added is 5~30% of the mass of the original powder after calcination, and the amount of graphite or cellulose added is 1~5% and 0.5~5% of the mass of the original powder after calcination, respectively.

[0016] Furthermore, the precursors of the active component, the first auxiliary agent, the second auxiliary agent, and the third auxiliary agent can each be a salt or oxide containing the corresponding metal ion. For example, they can be selected from one or more of nitrates, chlorides, and carbonates containing the corresponding metal cations, or they can be oxides directly.

[0017] Further, the precursor of the support can preferably be one or more selected from aluminum nitrate, aluminum sulfate, aluminum trichloride, and boehmite. In some preferred embodiments of the present invention, the Al2O3 support can be modified by a modifier, preferably SiO2. Preferably, the modifier SiO2 can be 0.1 to 50 parts by weight relative to 100 parts by weight of the Al2O3 support. The precursor of the modifier SiO2 can be one or more selected from Na2SiO3, kaolin, sodium silicate, or silica sol.

[0018] Furthermore, the precipitant can be selected from one or more of NaOH, Na2CO3, NaHCO3, (NH4)2CO3, NH4HCO3, and ammonia water, preferably Na2CO3, NaHCO3, or a mixture of both. When using a mixture of Na2CO3 and NaHCO3, the molar ratio of the two is preferably 1:19 to 19:1.

[0019] The present invention also provides a fully methanated catalyst prepared by the aforementioned preparation method. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0021] Examples 1 and 2 investigated the addition of potassium and magnesium using boehmite as a precursor; Examples 3 and 4 investigated the addition of potassium and magnesium using kaolin as a precursor. Example 1

[0022] S1. Weigh 53.51g Ni(NO3)2·6H2O, 7.74g La(NO3)3·6H2O, 14.36g Zr(NO3)4·5H2O, 4.53g Ca(NO3)2·4H2O, and 5.74g Cr(NO3)3·9H2O and dissolve them in 300ml of deionized water at 60℃ to obtain solution I.

[0023] S2. Weigh 37.27g Na2CO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution II; weigh 16.68g NaHCO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution III.

[0024] S3. Weigh 71.27g of pseudoboehmite, calcine it at 1200℃ for 4 hours, and then mix it with 200ml of deionized water at 60℃ to obtain solution IV.

[0025] S4. Slowly add solution I to solution II and stir for 2 hours to obtain precipitation system I; slowly add solution III to solution IV and stir for 2 hours to obtain precipitation system II.

[0026] S5. Add precipitation system II to precipitation system I, stir for 2 hours and let stand for 2 hours.

[0027] S6. Wash the precipitate system obtained in step S5 six times with deionized water at 60℃, and filter to obtain filter material. Dry the filter material in a forced-air drying oven at 110℃ for 4 hours. After drying, add 3.23g of nano-sized K2CO3, mix thoroughly, and then calcine at 550℃ for 6 hours at a rate of 1℃ / min to obtain raw powder. Add 4.16g of calcium aluminate to the calcined raw powder, mix thoroughly, and then add 2% of graphite by weight of the raw powder. After uniform mixing, press into tablets to obtain the finished catalyst.

[0028] The catalyst composition is: 31.25% NiO, 39.04% Al2O3, 11.99% ZrO2, 9.19% CaO, 3.64% La2O3, 2.83% K2O, and 2.06% Cr2O3. Example 2

[0029] S1. Weigh 53.51g Ni(NO3)2·6H2O, 7.74g La(NO3)3·6H2O, 14.36g Zr(NO3)4·5H2O, 4.53g Ca(NO3)2·4H2O, and 5.74g Cr(NO3)3·9H2O and dissolve them in 300ml of deionized water at 60℃ to obtain solution I.

[0030] S2. Weigh 37.27g Na2CO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution II; weigh 16.68g NaHCO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution III.

[0031] S3. Weigh 71.27g of pseudoboehmite, calcine it at 1200℃ for 4 hours, and then mix it with 200ml of deionized water at 60℃ to obtain solution IV.

[0032] S4. Slowly add solution I to solution II and stir for 2 hours to obtain precipitation system I; slowly add solution III to solution IV and stir for 2 hours to obtain precipitation system II.

[0033] S5. Add precipitation system II to precipitation system I, stir for 2 hours and let stand for 2 hours.

[0034] S6. Wash the precipitate system obtained in step S5 six times with deionized water at 60℃, and filter to obtain filter material. Dry the filter material in a forced-air drying oven at 110℃ for 4 hours. After drying, add 1.72g of nano-sized MgO, mix thoroughly, and then calcine at 550℃ for 6 hours at a rate of 1℃ / min to obtain raw powder. Add 4.16g of calcium aluminate to the calcined raw powder, mix thoroughly, and then add 2% of graphite by weight of the raw powder. After uniform mixing, press into tablets to obtain the finished catalyst.

[0035] The catalyst composition is: 31.44% NiO, 39.73% Al2O3, 12.06% ZrO2, 8.51% CaO, 3.79% La2O3, 2.36% MgO, and 2.11% Cr2O3. Example 3

[0036] S1. Weigh 67.24g Ni(NO3)2·6H2O, 8.24g La(NO3)3·6H2O, 13.62g Zr(NO3)4·5H2O, and 5.74g Cr(NO3)3·9H2O and dissolve them in 300ml of deionized water at 60℃ to obtain solution I.

[0037] S2. Weigh 38.38g Na2CO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution II; weigh 17.93g NaHCO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution III.

[0038] S3. Weigh 49.43g of kaolin powder, calcine it at 1200℃ for 4 hours, and then mix it with 150ml of deionized water at 60℃ to obtain solution IV.

[0039] S4. Slowly add solution I to solution II and stir for 2 hours to obtain precipitation system I; slowly add solution III to solution IV and stir for 2 hours to obtain precipitation system II.

[0040] S5. Add precipitation system II to precipitation system I, stir for 2 hours and let stand for 2 hours.

[0041] S6. Wash the precipitate system obtained in step S5 six times with deionized water at 60℃, and filter to obtain filter material. Dry the filter material in a forced-air drying oven at 110℃ for 4 hours. After drying, add 3.58g of nano-sized K2CO3, mix thoroughly, and then calcine at 550℃ for 6 hours at a rate of 1℃ / min to obtain raw powder. Add 4.16g of calcium aluminate to the calcined raw powder, mix thoroughly, and then add 2% of graphite by weight of the raw powder. After uniform mixing, press into tablets to obtain the finished catalyst.

[0042] The catalyst composition is: 30.19% NiO, 38.46% Al2O3, 12.29% ZrO2, 8.06% SiO2, 3.59% CaO, 3.25% La2O3, 2.11% K2O, and 2.05% Cr2O3. Example 4

[0043] S1. Weigh 67.24g Ni(NO3)2·6H2O, 8.24g La(NO3)3·6H2O, 13.62g Zr(NO3)4·5H2O, and 5.74g Cr(NO3)3·9H2O and dissolve them in 300ml of deionized water at 60℃ to obtain solution I.

[0044] S2. Weigh 38.38g Na2CO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution II; weigh 17.93g NaHCO3 and dissolve it in 300ml of deionized water at 60℃ to obtain solution III.

[0045] S3. Weigh 49.43g of kaolin powder, calcine it at 1200℃ for 4 hours, and then mix it with 150ml of deionized water at 60℃ to obtain solution IV.

[0046] S4. Slowly add solution I to solution II and stir for 2 hours to obtain precipitation system I; slowly add solution III to solution IV and stir for 2 hours to obtain precipitation system II.

[0047] S5. Add precipitation system II to precipitation system I, stir for 2 hours and let stand for 2 hours.

[0048] S6. Wash the precipitate system obtained in step S5 six times with deionized water at 60℃, and filter to obtain filter material. Dry the filter material in a forced-air drying oven at 110℃ for 4 hours. After drying, add 1.66g of nano-sized MgO, mix thoroughly, and then calcine at 550℃ for 6 hours at a rate of 1℃ / min to obtain raw powder. Add 4.16g of calcium aluminate to the calcined raw powder, mix thoroughly, and then add 2% of the raw powder mass of graphite. After uniform mixing, press into tablets to obtain the finished catalyst.

[0049] The catalyst composition is: 29.55% NiO, 41.87% Al2O3, 11.29% ZrO2, 6.44% SiO2, 3.18% La2O3, 2.74% CaO, 2.58% MgO, and 2.35% Cr2O3. Comparative Example 1

[0050] The catalyst was prepared according to the preparation method of Example 9 in patent CN103071507A, which yielded the comparative catalyst with the following composition: 44.00% NiO, 31.01% Al2O3, 12.63% ZrO2, 8.87% La2O3, 2.49% MgO, and 1.00% SiO2.

[0051] The performance of the fully methanation catalysts in the above examples and comparative examples was tested using the following methods: 1. Catalyst activity evaluation

[0052] The catalyst activity was evaluated under high-temperature reaction conditions for the production of synthetic natural gas from coal gasification via methanation, specifically examining the conversion rates of CO and CO2 on the catalyst.

[0053] High-temperature methanation reaction conditions: The volume percentage composition of the feed gas is: 34.32% H2, 7.44% CO, 2.94% CO2, 42.34% CH4, and 12.96% H2O.

[0054] Pressure: 3.2 MPa Temperature: 620℃ Volumetric hourly space velocity: 15000 h -1 2. Catalyst stability evaluation

[0055] High-temperature hydrothermal aging tests were conducted on the catalysts to examine the movement of hot spots in the catalyst bed and changes in catalyst strength after the tests, in order to determine and compare the high-temperature resistance of the catalysts. The high-temperature hydrothermal aging conditions were as follows: Aging temperature: 800℃ Atmosphere: H₂O + H₂, H₂O / H₂ = 9 / 1 (mol / mol) Volumetric hourly space velocity: 20000 h -1 Pressure: 3.2 MPa Aging time: 10 hours. 3. Catalyst strength

[0056] The strength of the fully methanated catalyst was tested according to the method in "HG / T 2782 Determination of Crushing Resistance of Fertilizer Catalyst Particles".

[0057] The performance evaluation results of the fully methanation catalysts of the embodiments and comparative examples of the present invention are shown in Table 1.

[0058] Table 1. Comparison of catalyst performance indicators between the embodiments of the present invention and the comparative examples.

[0059] The results from the examples and comparative examples show that the fully methanated catalyst of the present invention exhibits high strength after high-temperature aging, indicating that the catalyst has good high-temperature resistance. The minimal weight loss during aging tests indicates that the catalyst of the present invention is less prone to pulverization and performs better than the comparative example, thus enabling a longer service life for the catalyst in production equipment. In actual production, this catalyst is used in the first-stage reactor, while the CN103071507A patented catalyst is used in other reactors. This approach extends the catalyst's service life while ensuring the overall conversion efficiency of the reactor, meeting the requirements for long-term stable operation of the entire unit.

[0060] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. A method for preparing a fully methanated catalyst, characterized in that, Includes the following steps: S1. Mix the precursors of the active component, the first auxiliary agent, and the second auxiliary agent, and dissolve them in deionized water to obtain solution I. S2. Dissolve the precipitant in deionized water to prepare solutions II and III of different concentrations. S3. After calcining the precursor of the carrier at 900~1300℃ for 3~8 hours, add it to deionized water to prepare solution IV; S4. Add solution I to solution II to induce precipitation, and obtain precipitation system I. Solution III was added to solution IV to induce precipitation, resulting in precipitation system II. S5. Mix precipitation system I and precipitation system II, stir for 0.5 to 10 hours, and let stand for 0.5 to 10 hours. S6. The mixed precipitate system is filtered, dried, and the precursor of the third auxiliary agent is added. The mixture is then calcined and shaped to produce a fully methanated catalyst. The fully methanated catalyst comprises an active component Ni comprising 3-60% of the total mass of the catalyst based on elemental metal, a first promoter comprising 2-30% of the total mass of the catalyst based on oxides, a second promoter comprising 0.5-30% of the total mass of the catalyst based on oxides, a third promoter comprising 1-5% of the total mass of the catalyst based on oxides, and the balance being a support Al2O3. The first promoter is selected from one or more of La2O3, CeO2, Pr2O3, and Sm2O3; the second promoter is selected from one or more of Fe2O3, TiO2, CuO, ZnO, MoO3, Co3O4, ZrO2, Cr2O3, CaO, SrO, and BaO; and the third promoter is selected from one of K2O or MgO.

2. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, In steps S1 to S3, the temperature of the deionized water used to prepare the solutions is 40–90°C, the molar concentration ratio of solution I to solution II is 1:1.0–5.0, and the molar concentration ratio of solution III to solution IV is 1:1.0–5.

0.

3. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, In step S4, during the preparation of precipitate system I, the volume ratio of solution I to solution II is 1:1.5 to 4.

5.

4. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, In step S4, during the preparation of precipitate system II, the volume ratio of solution IV to solution III is 1:3 to 9.

5. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, In step S5, the volume ratio of precipitation system I to precipitation system II is 1:0.1 to 14.

8.

6. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, Step S6 specifically includes: washing, filtering, and drying the mixed precipitate system; adding one or more of the precursors of the nano-scale third auxiliary agent, such as K2CO3, MgCO3, CaCO3, K2O, MgO, and CaO, after drying; calcining to obtain the raw powder; adding calcium aluminate to the raw powder; and then adding graphite or cellulose. After mixing evenly, the mixture is pressed into tablets to obtain the finished catalyst.

7. The method for preparing the fully methanated catalyst according to claim 6, characterized in that, The drying temperature is 70~110℃, the calcination temperature is 250~700℃, and the calcination time is 2~10 hours; the amount of calcium aluminate added is 5~30% of the mass of the original powder after calcination, and the amount of graphite or cellulose added is 1~5% and 0.5~5% of the mass of the original powder after calcination, respectively.

8. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, The precursors of the active component, the first auxiliary agent, the second auxiliary agent, and the third auxiliary agent are soluble salts or oxides containing the corresponding metal ions, respectively; the precursor of the support is selected from one or more of aluminum nitrate, aluminum sulfate, aluminum trichloride, and boehmite.

9. The method for preparing the fully methanated catalyst according to claim 1, characterized in that, The precipitant is selected from one or more of NaOH, Na2CO3, NaHCO3, (NH4)2CO3, NH4HCO3 and ammonia water.

10. A fully methanation catalyst prepared by the method according to any one of claims 1-9.

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