Nickel-based catalyst, preparation method thereof and application of nickel-based catalyst in methane dry gas reforming reaction
By using the branches -like medium -shaped meter -like silicon carrier and salt in the nickel -based catalyst, the sintering of nickel nanoparticles was suppressed, and the problem of being easily lost in the rejuvenation of the traditional catalyst in the rejuvenation of the methane dry gas, and realized the catalysts of the catalyst. High activity and long life.
Patent Information
- Application Number
- CN202411327848.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2025-01-24
AI Technical Summary
Traditional nickel-based catalysts are prone to sintering during methane dry gas reforming reaction, resulting in the deactivation of the catalyst, high energy consumption and excessive reaction temperature.
A dendritic mesoporous silica carrier is used to load nickel salts and zirconium salts. The nickel-based catalyst is prepared through heat treatment and reduction treatment, and oxygen vacancies and spatial coordination confinement effects are used to inhibit the sintering of nickel nanoparticles.
It significantly improves the activity of the catalyst and the resistance of accumulation, prolongs the service life of the catalyst, and maintains stability in high temperature reactions.
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Figure CN119346113A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalyst preparation, and in particular to a nickel-based catalyst and a preparation method thereof and application thereof in a methane dry gas reforming reaction. Background Art
[0002] With the continuous growth of global energy demand and the increasing depletion of fossil fuel resources, the development of clean and efficient energy conversion technologies has become an important topic of current scientific research. Methane, as the main component of natural gas, occupies an important position in the adjustment of energy structure due to its abundant reserves, low carbon and environmental protection characteristics. However, the stability of methane molecular structure makes its high-value conversion face many challenges. Traditional methods such as combustion and cracking not only consume a lot of energy, but also easily produce a large amount of greenhouse gases, exacerbating the problem of global climate change.
[0003] The dry methane reforming (DRM) reaction provides a new approach to solving the above problems. This reaction can not only effectively utilize methane and carbon dioxide, two greenhouse gases, to reduce the negative impact of their emissions on the environment, but also generate syngas, an important chemical raw material, to provide a material basis for the synthesis of high value-added chemicals. Its main reaction equation is:
[0004] Methane dry gas reforming reaction CH4(g)+CO2(g)→2H2(g)+2CO(g)
[0005] Methane cracking reaction CH4(g)→C(s)+2H2(g)
[0006] Carbon monoxide disproportionation reaction 2CO(g)→C(s)+CO2(g)
[0007] Reverse water gas reaction CO2(g)+H2(g)→H2O(g)+CO(g)
[0008] This reaction process can be seen as the synergistic effect of methane and carbon dioxide. With the help of DRM technology, CH4 and CO2, two greenhouse gases, are simultaneously converted into synthesis gas with a H2 / CO ratio close to one. The synthesis gas can be directly used for Fischer-Tropsch synthesis to produce chemicals with high added value. There are three main side reactions in the DRM reaction process, among which methane cracking and carbon monoxide disproportionation will cause carbon deposition in the reaction process, while the reverse water gas reaction mainly affects the hydrogen-carbon ratio of the product.
[0009] Suitable catalysts play a key role in the DRM process. Traditional DRM technology mainly uses nickel-based catalysts to produce carbon monoxide and hydrogen through the reaction of methane and carbon dioxide under high temperature and high pressure conditions. Although this method has achieved certain success, it still faces problems such as high energy consumption and high reaction temperature. At the same time, nickel-based catalysts are prone to sintering and producing carbon deposits during the reaction, which causes the catalyst to deactivate. Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention
[0010] The present invention aims to provide a nickel-based catalyst and a preparation method thereof and application in a methane dry gas reforming reaction. The catalyst utilizes novel oxygen vacancies and spatial coordinated confinement effects to suppress the problem of easy sintering of nickel nanoparticles in high-temperature reactions, while having good structural characteristics and a high specific surface area, and exhibiting excellent catalytic activity and high resistance to carbon deposition.
[0011] In a first aspect, the present invention provides a nickel-based catalyst, which includes a dendritic mesoporous silica carrier and a nickel salt and an auxiliary agent loaded on the surface of the carrier, wherein the auxiliary agent includes a zirconium salt.
[0012] Optionally, the nickel salt includes at least one of nickel nitrate, nickel acetate, nickel chloride, nickel sulfate and nickel acetylacetonate.
[0013] Optionally, the nickel element in the nickel salt accounts for 3wt%-10wt% of the total mass of the catalyst.
[0014] Optionally, the zirconium salt includes at least one of zirconium nitrate, zirconium sulfate and zirconium acetate.
[0015] Optionally, the zirconium element in the zirconium salt accounts for 5wt%-10wt% of the total mass of the catalyst.
[0016] Optionally, the addition of the zirconium salt can increase the oxygen vacancy concentration of the catalyst, effectively improving the activity and anti-carbon deposition performance of the catalyst.
[0017] In a second aspect, the present invention provides a method for preparing the above catalyst, comprising the following steps:
[0018] Surface activation of the silicon source mixed solution is performed to obtain a dendritic mesoporous carrier;
[0019] The nickel salt and the zirconium salt are loaded on the surface of the carrier and then heat treated to generate a catalyst precursor; the catalyst precursor is reduced to obtain a nickel-based catalyst.
[0020] The catalyst preparation method provided by the present invention utilizes the special dendritic structure of the carrier to confine the active metal nickel on the surface space, significantly improve the dispersion of the metal nickel, and further introduce zirconium to construct rich oxygen vacancies. The method effectively suppresses the problem of easy sintering of nickel nanoparticles in high-temperature reactions, significantly improves the activity and anti-carbon deposition performance of the catalyst, and thus increases the service life of the catalyst.
[0021] Optionally, the silicon source mixed solution includes tetraethyl orthosilicate, n-pentanol and cyclohexane.
[0022] Optionally, the volume ratio of tetraethyl orthosilicate, n-pentanol and cyclohexane in the silicon source mixed solution is 1:(1-2):(1-3).
[0023] Optionally, the surface activation of the silicon source mixed solution includes: mixing the silicon source mixed solution and the surfactant and then placing the mixture in an oil bath at 70° C.-120° C. for 4 h-12 h.
[0024] Optionally, the surfactant includes CTAB and urea.
[0025] Optionally, the mass ratio of CTAB to urea in the surfactant is 1:(1-2).
[0026] Optionally, the volume ratio of the silicon source mixed liquid and the surfactant is (1-2.5):1.
[0027] Optionally, the heat treatment includes: reacting at 500° C.-800° C. for 2 h-6 h in an inert gas atmosphere.
[0028] Optionally, heat treatment can make the nickel and zirconium in the catalyst evenly dispersed while forming strong interactions, which can inhibit sintering of the metals at high temperatures.
[0029] Optionally, the inert gas atmosphere includes a mixed gas of hydrogen and argon.
[0030] Optionally, when reducing the catalyst precursor, the reaction atmosphere is a reducing atmosphere.
[0031] In a third aspect, the present invention provides use of a catalyst prepared by any of the above optional preparation methods in a methane dry gas reforming reaction.
[0032] When the catalyst provided by the present invention is used for methane dry gas reforming reaction, compared with other catalysts, it has excellent stability and anti-carbon deposition performance, and meets the high standard requirements of the industrial production field for long-term stable performance and high-efficiency utilization of catalysts.
[0033] Optionally, under the conditions of 600°C-900°C and pressure of 1MPa-5MPa, methane and carbon dioxide generate carbon monoxide and hydrogen in the presence of a catalyst. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly introduce the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.
[0035] Figure 1 This is a SEM image of the DMS carrier prepared in Example 1 of the present invention;
[0036] Figure 2 Thermogravimetric analysis results of the nickel-based catalysts prepared in Example 1 and Comparative Example 1 of the present invention for methane dry gas reforming reaction at 100° C. to 900° C. for 20 hours;
[0037] Figure 3 The methane conversion rates of the nickel-based catalyst prepared in Example 1 of the present invention and Comparative Example 1 and the conventional commercial Ni / Al2O3 catalyst in the methane dry gas reforming reaction at 650°C from 0h to 20h. DETAILED DESCRIPTION
[0038] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described through the following embodiments in conjunction with the accompanying drawings. However, the following embodiments are illustrative and are only used to specifically describe the present invention rather than to limit the present invention.
[0039] The invention provides a nickel-based catalyst, which comprises a dendritic mesoporous silica carrier, a nickel salt and an auxiliary agent loaded on the surface of the carrier, and the auxiliary agent comprises a zirconium salt.
[0040] In some embodiments, the nickel salt includes at least one of nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, and nickel acetylacetonate.
[0041] In some embodiments, the nickel element in the nickel salt accounts for 3 wt%-10 wt% of the total mass of the catalyst.
[0042] In some embodiments, the zirconium salt includes at least one of zirconium nitrate, zirconium sulfate, and zirconium acetate.
[0043] In some embodiments, the zirconium element in the zirconium salt accounts for 5 wt%-10 wt% of the total mass of the catalyst.
[0044] The present invention also provides a method for preparing the above catalyst, comprising the following steps:
[0045] S1, surface activation of the silicon source mixed solution to obtain a dendritic mesoporous carrier;
[0046] S2, loading nickel salt and zirconium salt on the surface of the carrier and then heat treating to generate a catalyst precursor; reducing the catalyst precursor to obtain a nickel-based catalyst.
[0047] In fact, when executing step S1, the following sub-steps are included:
[0048] S1.1. At room temperature, tetraethyl orthosilicate, n-pentanol and cyclohexane are mixed and stirred to obtain a silicon source mixed solution; after CTAB and urea are dissolved in deionized water, ultrasonically treated at 35°C-45°C for 15min-25min in an ultrasonic bath, stirred until the solution is clear to obtain a surfactant;
[0049] S1.2. At room temperature, slowly pour the silicon source mixture into the surfactant, stir evenly and transfer to a high-pressure reactor in an oil bath at 100℃-120℃ for 2h-4h, add anhydrous ethanol to break the emulsion, let it stand, take the lower layer and centrifuge for washing, dry in an oven at 80℃-100℃ for 4h-6h, grind into powder, and calcine in a muffle furnace at 450℃-550℃ for 6h-8h to obtain a DMS carrier.
[0050] In some embodiments, when performing step S1.1, the volume ratio of tetraethyl orthosilicate, n-pentanol and cyclohexane in the silicon source mixture is 1:(1-2):(1-3).
[0051] In some embodiments, when performing step S1.1, the mass ratio of CTAB to urea in the surfactant is 1:(1-2).
[0052] In some embodiments, when executing step S1.2, the volume ratio of the silicon source mixed liquid and the surfactant is (1-2.5):1.
[0053] In some embodiments, when performing step S2, the heat treatment includes: reacting at 500° C.-800° C. for 2 h-6 h in an inert gas atmosphere.
[0054] In some embodiments, when performing step S2, the inert gas atmosphere includes a mixture of hydrogen and argon.
[0055] In some embodiments, when performing step S2, the reaction atmosphere during the reduction of the catalyst precursor is a reducing atmosphere.
[0056] The present invention also provides an application of the catalyst in a methane dry gas reforming reaction, comprising:
[0057] Under the conditions of 600℃-900℃ and pressure of 1MPa-5MPa, methane and carbon dioxide generate carbon monoxide and hydrogen under the action of catalyst.
[0058] Example 1
[0059] Embodiment 1 of the present invention provides a method for preparing a nickel-based catalyst, comprising the following steps:
[0060] S1.1. At room temperature, 114 mL of cyclohexane, 3.8 mL of n-pentanol and 7 mL of ethyl orthosilicate were mixed and stirred to obtain a silicon source mixture; 2.56 g of CTAB and 1.58 g of urea were dissolved in 76 mL of deionized water, ultrasonicated at 40°C for 20 min in an ultrasonic bath, and stirred until the solution was clear to obtain a surfactant;
[0061] S1.2, at room temperature, slowly pour the silicon source mixture into the surfactant and stir for 30 minutes, then transfer to a high-pressure reactor in an oil bath at 100°C for 4 hours, with a stirring rate of 550 rpm / min, add anhydrous ethanol to break the emulsion after the oil bath, let it stand for 30 minutes, take out the lower layer for centrifugal washing, dry in an oven at 80°C for 6 hours, grind into powder, and calcine in a muffle furnace at 550°C for 6 hours to obtain a DMS carrier;
[0062] S2. Dissolve nickel nitrate hexahydrate and zirconium nitrate pentahydrate in ethylene glycol at room temperature, stir them thoroughly to make them completely dissolved to obtain a 1 mol / L solution, add 1.0 g of DMS carrier to the solution, stir for 12 hours, and then vacuum dry at 80°C for 12 hours. After drying, grind into powder and put it into a tube furnace. After calcining for 4 hours in a nitrogen atmosphere, calcinate for 4 hours in an air atmosphere to finally obtain a Ni-ZrO2 / DMS catalyst.
[0063] In a fixed-bed reactor, a 10% H2-Ar mixed gas with a flow rate of 30 mL / min was used for in-situ reduction at 75°C for 2 h to prepare a Ni-ZrO2 / DMS catalyst with synergistic oxygen vacancies and spatial confinement, which can be used for methane dry gas reforming reactions.
[0064] Comparative Example 1
[0065] Comparative Example 1 of the present invention provides a method for preparing a nickel-based catalyst, which is different from Example 1 in that zirconium nitrate pentahydrate is not added in step S2, and a Ni / DMS catalyst is finally prepared.
[0066] Stability test
[0067] The catalysts prepared in Example 1 and Comparative Example 1 and the conventional commercial Ni / Al2O3 catalyst were used for methane dry gas reforming reaction respectively:
[0068] First, Ni-ZrO2 / DMS catalyst powder, Ni / DMS catalyst powder and Ni / Al2O3 catalyst powder were pressed and sieved to 60 mesh to prepare granular catalysts. 50 mg of fresh catalyst was respectively loaded into a quartz tube with an inner diameter of 6 mm and blocked at both ends with quartz wool. The catalyst was heated from room temperature to 750°C in a 10% H2 / Ar atmosphere with a space velocity of 30 mL / min and maintained for 2 h. After the reduction was completed, the reaction gas (CH4:CO2=1:1, WHSV=18,000 mL g cat -1 h -1 , p = 1atm), during the cooling process from 800℃ to 400℃, the methane conversion rate and thermogravimetry of the catalyst were tested every 50℃.
[0069] Figure 2Thermogravimetric analysis results of the two catalysts prepared in Example 1 and Comparative Example 1 were respectively subjected to methane dry gas reforming reaction at 100°C to 900°C for 20 hours. The results showed that with the increase of the reaction temperature, the stability of the Ni-ZrO2 / DMS catalyst did not show a downward trend and no carbon deposition was observed in the thermogravimetric analysis, while the carbon deposition content of the Ni / DMS catalyst reached 7.4% at 650°C.
[0070] Figure 3 The nickel-based catalyst prepared in Example 1 and Comparative Example 1 and the traditional commercial Ni / Al2O3 catalyst were respectively subjected to methane dry gas reforming reaction at 650°C for 0h to 20h of methane conversion. The results showed that the methane conversion rate of the Ni-ZrO2 / DMS catalyst was stable at about 56%, without obvious deactivation, the methane conversion rate of the Ni / DMS catalyst was 52%-53%, and the catalytic activity decreased slightly, while the methane conversion rate of the Ni / Al2O3 catalyst decreased from 47% to 38%, and the catalytic activity decreased significantly.
[0071] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.
Claims
1. A nickel-based catalyst, characterized in that The catalyst comprises a dendritic mesoporous silica carrier, a nickel salt and an auxiliary agent loaded on the surface of the carrier, and the auxiliary agent comprises a zirconium salt.
2. The catalyst according to claim 1, characterized in that The nickel salt includes at least one of nickel nitrate, nickel acetate, nickel chloride, nickel sulfate and nickel acetylacetonate; the zirconium salt includes at least one of zirconium nitrate, zirconium sulfate and zirconium acetate; the nickel element in the nickel salt accounts for 3wt%-10wt% of the total mass of the catalyst; the zirconium element in the zirconium salt accounts for 5wt%-10wt% of the total mass of the catalyst.
3. A method for preparing the catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: Surface activation of the silicon source mixed solution is performed to obtain a dendritic mesoporous carrier; The nickel salt and the zirconium salt are loaded on the surface of the carrier and then heat treated to generate a catalyst precursor; the catalyst precursor is reduced to obtain a nickel-based catalyst.
4. The preparation method according to claim 3, characterized in that: The silicon source mixed liquid includes tetraethyl orthosilicate, n-pentanol and cyclohexane, wherein the volume ratio of tetraethyl orthosilicate, n-pentanol and cyclohexane is 1:(1-2):(1-3).
5. The preparation method according to claim 3, characterized in that: The surface activation of the silicon source mixed solution comprises: mixing the silicon source mixed solution and the surfactant, and then placing the mixture in an oil bath at 70° C.-120° C. for 4 h-12 h.
6. The preparation method according to claim 5, characterized in that: The surfactant includes CTAB and urea, wherein the mass ratio of CTAB to urea is 1:(1-2); the volume ratio of the silicon source mixed liquid and the surfactant is (1-2.5):
1.
7. The preparation method according to claim 3, characterized in that: The heat treatment comprises: reacting at 500° C.-800° C. for 2 h-6 h in an inert gas atmosphere.
8. The preparation method according to claim 7, characterized in that: The inert gas atmosphere includes a mixed gas of hydrogen and argon.
9. A method for preparing the catalyst according to any one of claims 1 to 2, or a catalyst prepared by the method according to any one of claims 3 to 8, characterized in that: Application in methane dry gas reforming reaction.
10. The use according to claim 9, characterized in that: Under the conditions of 600℃-900℃ and pressure of 1MPa-5MPa, methane and carbon dioxide generate carbon monoxide and hydrogen under the action of catalyst.