阅读说明：本技术 低温高活性镍基双金属甲烷化催化剂及其制备方法与应用 (Low-temperature high-activity nickel-based bimetallic methanation catalyst and preparation method and application thereof ) 是由 辛忠 高文莉 于 2018-09-12 设计创作，主要内容包括：本发明公开了一种低温高活性镍基双金属甲烷化催化剂,以介孔分子筛SBA-16-EG为载体,以金属Ni为第一活性组分,以第二活性金属M作为第二活性组分,所述第二活性金属M为Fe、Co、La、Mo中的至少一种；其中,以100重量份的催化剂为基准,以金属元素计,镍的含量为5～30重量份,第二活性金属M的含量为0.1～10重量份,余量为介孔分子筛SBA-16-EG。本发明提供的低温高活性镍基双金属甲烷化催化剂不含有贵金属组分,制备方法简单易行,前驱体无浪费,且性能较高,在性价比上有较大的优势。(The invention discloses a low-temperature high-activity nickel-based bimetallic methanation catalyst, which takes mesoporous molecular sieve SBA-16-EG as a carrier, metal Ni as a first active component and a second active metal M as a second active component, wherein the second active metal M is at least one of Fe, Co, La and Mo; wherein, based on 100 weight portions of catalyst, calculated by metal elements, the content of nickel is 5-30 weight portions, the content of the second active metal M is 0.1-10 weight portions, and the balance is mesoporous molecular sieve SBA-16-EG. The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention does not contain precious metal components, the preparation method is simple and easy to implement, the precursor is not wasted, the performance is higher, and the cost performance is higher.)

1. A low-temperature high-activity nickel-based bimetallic methanation catalyst is characterized in that: taking mesoporous molecular sieve SBA-16-EG as a carrier, metal Ni as a first active component, and a second active metal M as a second active component, wherein the second active metal M is at least one of Fe, Co, La and Mo; wherein, based on 100 weight portions of catalyst, calculated by metal elements, the content of nickel is 5-30 weight portions, the content of the second active metal M is 0.1-10 weight portions, and the balance is mesoporous molecular sieve SBA-16-EG.

2. The low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 1, characterized in that: the specific surface area of the low-temperature high-activity nickel-based bimetallic methanation catalyst is 500-1000 m²(ii) a pore diameter of 3 to 12nm and a pore volume of 0.4 to 1.4m³/g。

3. The low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 1, characterized in that: the mesoporous molecular sieve SBA-16-EG is pretreated by glycol;

the specific surface area of the mesoporous molecular sieve SBA-16-EG is 500-1000 m²Preferably 600 to 890 m/g²The pore diameter is 2-12 nm, preferably 2-10 nm, the pore wall is 2-6 nm, and the pore volume is 0.4-1.4 cm³Preferably 0.4 to 1 cm/g³/g。

4. A preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in any one of claims 1 to 3, characterized by comprising the following steps: the method comprises the following steps:

dissolving nickel salt and second active metal M salt in a solvent to prepare an impregnation solution, wherein the concentration range of the nickel salt in the impregnation solution is 0.1-1 g/mL, and the concentration range of the second active metal M salt is 0.005-0.2 g/mL; soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in a soaking solution by adopting an isometric co-soaking method, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is 1 (0.2-2) to 0.008-0.2; stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst;

or dissolving nickel salt in a solvent to prepare a nickel salt solution with the concentration range of 0.1-1 g/mL, dissolving a second active metal M salt in the solvent to prepare a second active metal M salt solution with the concentration range of 0.004-0.1 g/mL, soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in the nickel salt solution by adopting an isometric impregnation method, stirring, standing, vacuum drying, roasting, and then soaking in the second active metal M salt solution, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is (0.2-2): 0.008-0.2; stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst;

or dissolving nickel salt in a solvent to prepare a nickel salt solution with the concentration range of 0.1-1 g/mL, dissolving a second active metal M salt in the solvent to prepare a second active metal M salt solution with the concentration range of 0.004-0.1 g/mL, soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in the second active metal M salt solution by adopting an isometric impregnation method, stirring, standing, vacuum drying, roasting, and then soaking in the nickel salt solution, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is (0.2-2): 0.008-0.2; and stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst.

5. The preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 4, characterized in that: the pretreatment of the mesoporous molecular sieve SBA-16-EG comprises the following steps: soaking dry mesoporous SiO2 molecular sieve SBA-16-EG in ethylene glycol in equal volume, stirring uniformly, standing at room temperature, and drying to obtain pretreated mesoporous molecular sieve SBA-16-EG;

the mesoporous molecular sieve SBA-16-EG is dried at the temperature of 80-120 ℃ for 2-24 hours, preferably 8-10 hours.

6. The preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 4, characterized in that: the nickel salt is at least one of nickel chloride, nickel sulfate, nickel acetate, nickel oxalate and nickel nitrate;

the second active metal M salt is at least one of ferric nitrate, cobalt nitrate, lanthanum nitrate, ammonium molybdate and cobaltous nitrate.

7. The preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 4, characterized in that: the solvent is at least one of deionized water, methanol, ethanol, acetic acid, ethyl acetate, chloroform and acetone;

the temperature of the isometric impregnation method and the isometric co-impregnation method is room temperature, and the time is 2-12 h, preferably 4-8 h.

8. The preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 4, characterized in that: the temperature of the vacuum drying is 10-200 ℃, preferably 50-100 ℃, and the time is 1-24 hours, preferably 6-8 hours;

the roasting temperature is 400-900 ℃, preferably 450-600 ℃, and the roasting time is 0.5-10 hours, preferably 3-6 hours;

the screening is performed by a 200-mesh sample separation screen.

9. Use of a low temperature high activity nickel based bimetallic methanation catalyst as claimed in any one of claims 1 to 3 in the production of methane from synthesis gas.

10. The use of the low-temperature high-activity nickel-based bimetallic methanation catalyst as claimed in claim 9 in the preparation of methane from synthesis gas, characterized in that: the conditions for preparing methane from the synthesis gas are as follows: the volume airspeed of the synthesis gas treated by the catalyst is 3000-60000 h^-1The pressure is from normal pressure to 3.0MPa, the temperature is from 200 ℃ to 500 ℃, and H in the synthesis gas₂The ratio of/CO is 2-4.

Technical Field

The invention belongs to the technical field of industrial catalysis, and relates to a low-temperature high-activity nickel-based bimetallic methanation catalyst, and a preparation method and application thereof.

Background

The methanation technology is the research focus for developing the coal-to-natural gas technology, and the core of the technology is a high-efficiency and stable methanation catalyst. A large amount of heat is evolved due to methanation of the synthesis gasAmount (CO + 3H)₂→CH₄+H₂O,ΔH_298KAt-206.1 kJ/mol), the reaction proceeds in the forward direction at both low and high temperatures. However, low temperatures can dramatically reduce the reaction rate and thus the throughput, in terms of reaction kinetics. Therefore, it is necessary to research a catalyst with lower activation energy so that the catalyst can have higher activity at lower temperature, thereby achieving the dual harvest of yield and benefit.

The current industrial application adopts a higher-temperature catalyst, which can utilize a large amount of heat released by the reaction, but the benefit and risk are compatible, and the Ni-based catalyst at high temperature can cause Ni atoms to be thermally migrated through an Ostwald ripening mechanism due to the lower Taman temperature, so that the catalyst particles are agglomerated and even sintered to be inactivated, so that the research of the Ni-based methanation catalyst with high activity at lower temperature is more necessary. Disproportionation of carbon monoxide 2CO (g) → C(s) + CO₂(g) At higher temperatures, inactive carbon species are formed and the accumulation of carbon species also leads to deactivation of the Ni-based catalyst, so that the reaction at lower temperatures greatly reduces the formation of carbon and thus prolongs the service life of the catalyst.

Patent CN 104511314A proposes a low-temperature methanation catalyst and a preparation method thereof, and Raney alloy particles are partially embedded and loaded on the surface of an organic polymer material by adopting a Raney method, so that the content of 0.5% of CO in raw material gas can be reduced to be lower than 1ppm at 150 ℃, but the loading amount of active metal nickel is higher (30-60 wt%), and the catalyst cannot be directly used for methanation of synthesis gas. Patent CN 103706373A proposes a low-temperature high-activity methanation catalyst, wherein nickel is an active component, and Al₂O₃Is used as a carrier, MgO is used as a structural assistant, and rare earth metal lanthanum and metal manganese are used as active assistants, so that CO in the feed gas can be removed₂/CH₄/H₂CO 0.880/94.097/5.023₂The content was reduced to 10 ppm. But the content of the supported metal nickel is still high (18-45wt percent), which causes waste of active metal.

Disclosure of Invention

In order to overcome the defects of low utilization rate of metal Ni, easy agglomeration of Ni particles and easy catalyst deactivation caused by carbon deposition of a high-temperature Ni-based methanation catalyst in the prior art, the invention aims to provide a low-temperature high-activity nickel-based bimetallic methanation catalyst with high activity and good stability under a low-temperature condition.

The invention also aims to provide a preparation method of the low-temperature high-activity nickel-based bimetallic methanation catalyst, which has the advantages of simplicity, convenience, low cost and the like.

The invention further aims to provide application of the low-temperature high-activity nickel-based bimetallic methanation catalyst.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the invention provides a low-temperature high-activity nickel-based bimetallic methanation catalyst, which takes mesoporous molecular sieve SBA-16-EG as a carrier, metal Ni as a first active component and a second active metal M as a second active component, wherein the second active metal M is at least one of Fe, Co, La and Mo; wherein, based on 100 weight portions of catalyst, calculated by metal elements, the content of nickel is 5-30 weight portions, the content of the second active metal M is 0.1-10 weight portions, and the balance is mesoporous molecular sieve SBA-16-EG. The mesoporous molecular sieve SBA-16-EG has stable chemical properties, good heat conduction performance and large specific surface area.

The specific surface area of the low-temperature high-activity nickel-based bimetallic methanation catalyst is 500-1000 m²(ii) a pore diameter of 3 to 12nm and a pore volume of 0.4 to 1.4m³/g。

The mesoporous molecular sieve SBA-16-EG is pretreated by ethylene glycol.

The specific surface area of the mesoporous molecular sieve SBA-16-EG is 500-1000 m²Preferably 600 to 890 m/g²The pore diameter is 2-12 nm, preferably 2-10 nm, the pore wall is 2-6 nm, and the pore volume is 0.4-1.4 cm³Preferably 0.4 to 1 cm/g³/g。

The metal Ni is NiO and Ni₂O₃In the form of an alloy or in the form of a solid solution.

The invention provides a preparation method of a low-temperature high-activity nickel-based bimetallic methanation catalyst, which comprises the following steps of:

dissolving nickel salt and second active metal M salt in a solvent to prepare an impregnation solution, wherein the concentration range of the nickel salt in the impregnation solution is 0.1-1 g/mL, and the concentration range of the second active metal M salt is 0.005-0.2 g/mL; soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in a soaking solution by adopting an isometric co-soaking method, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is 1 (0.2-2) to 0.008-0.2; stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst;

or dissolving nickel salt in a solvent to prepare a nickel salt solution with the concentration range of 0.1-1 g/mL, dissolving a second active metal M salt in the solvent to prepare a second active metal M salt solution with the concentration range of 0.004-0.1 g/mL, soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in the nickel salt solution by adopting an isometric impregnation method, stirring, standing, vacuum drying, roasting, and then soaking in the second active metal M salt solution, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is (0.2-2): 0.008-0.2; stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst;

or dissolving nickel salt in a solvent to prepare a nickel salt solution with the concentration range of 0.1-1 g/mL, dissolving a second active metal M salt in the solvent to prepare a second active metal M salt solution with the concentration range of 0.004-0.1 g/mL, soaking the dried pretreated mesoporous molecular sieve SBA-16-EG in the second active metal M salt solution by adopting an isometric impregnation method, stirring, standing, vacuum drying, roasting, and then soaking in the nickel salt solution, wherein the mass ratio of the mesoporous molecular sieve SBA-16-EG to the nickel salt and the second active metal M salt is (0.2-2): 0.008-0.2; and stirring, standing, vacuum drying, roasting, grinding and screening to obtain the low-temperature high-activity nickel-based bimetallic methanation catalyst.

The pretreatment of the mesoporous molecular sieve SBA-16-EG comprises the following steps: soaking dry mesoporous SiO2 molecular sieve SBA-16-EG in ethylene glycol in equal volume, stirring uniformly, standing at room temperature, and drying to obtain the pretreated mesoporous molecular sieve SBA-16-EG.

The mesoporous molecular sieve SBA-16-EG is dried at the temperature of 80-120 ℃ for 2-24 hours, preferably 8-10 hours.

The nickel salt is at least one of nickel chloride, nickel sulfate, nickel acetate, nickel oxalate and nickel nitrate.

The second active metal M salt is at least one of ferric nitrate, cobalt nitrate, lanthanum nitrate, ammonium molybdate and cobaltous nitrate.

The solvent is at least one of deionized water, methanol, ethanol, acetic acid, ethyl acetate, chloroform and acetone.

The temperature of the isometric impregnation method and the isometric co-impregnation method is room temperature, and the time is 2-12 h, preferably 4-8 h.

The temperature of the vacuum drying is 10-200 ℃, preferably 50-100 ℃, and the time is 1-24 hours, preferably 6-8 hours.

The roasting temperature is 400-900 ℃, preferably 450-600 ℃, and the roasting time is 0.5-10 hours, preferably 3-6 hours.

The screening is performed by a 200-mesh sample separation screen.

In the preparation process of the catalyst, the solvent of the impregnation liquid is changed, so that the aggregation and growth of active component particles can be inhibited, the size of small nickel particles is maintained, and the sintering of the active component particles can be prevented in the reduction process of the catalyst, so that the dispersion degree of the active component nickel in the catalyst is improved, and the low-temperature activity and the stability of the catalyst are influenced finally.

The invention also provides application of the low-temperature high-activity nickel-based bimetallic methanation catalyst in preparation of methane from synthesis gas.

The conditions for preparing methane from the synthesis gas are as follows: the volume airspeed of the synthesis gas treated by the catalyst is 3000-60000 h^-1The pressure is from normal pressure to 3.0MPa, the temperature is from 200 ℃ to 500 ℃, and H in the synthesis gas₂The ratio of/CO is 2-4.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

the low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention takes mesoporous molecular sieve SBA-16-EG with stable chemical properties and good thermal conductivity as a carrier, and the prepared catalyst has the advantages of large specific surface area, high catalytic activity (CO can be completely converted at 270 ℃), good stability and the like. The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention has the lowest complete conversion temperature of 265 ℃ and the methane selectivity of over 90% during complete conversion.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention does not contain precious metal components, the preparation method is simple and easy to implement, the precursor is not wasted, the performance is higher, and the cost performance is higher.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention uses the second active component modified Ni-based catalyst, the second active metal M can form a bimetallic oxide with the active component Ni in the roasting process of catalyst preparation, the two metals can be uniformly dispersed in the pre-reduction process of the catalyst, the obtained nickel-based bimetallic catalyst has the advantages of good catalytic activity, high methane selectivity, long catalyst life and the like under the low-temperature condition, and the catalyst has the air speed of 15000h at the normal pressure, 270 ℃ and the air speed of 15000h^-1The conversion rate of CO can reach 100 percent, the selectivity of methane is more than 90 percent, the yield of methane is more than 90 percent, and the method has great industrial prospect.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention adopts a mesoporous molecular sieve SBA-16-EG with large specific surface area, stable mechanical strength and good high temperature resistance as a carrier of the Ni-based methanation catalyst, adopts metal Ni as an active component, and adds Fe, Co, La, Mo and the like as a second active component, and prepares a series of Ni-based SBA-16-EG type methanation catalysts by an isometric impregnation method, and has high methanation activity at lower temperature.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention adopts the mesoporous molecular sieve SBA-16-EG which is three-dimensional cage-shaped SiO₂Molecular sieve materials, three-dimensional structures for mass and heat transferThe effect is better, the problem that active components block the pore channels of the molecular sieve is solved, the molecular sieve has a multi-level pore structure, and larger cage-shaped pores can play a role in limiting the active components. The larger specific surface area and pore volume may provide sufficient space for dispersion of the active component.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention shows excellent activity and methane selectivity in the reaction of preparing methane from synthesis gas, has activity in a temperature range of 200-500 ℃, can completely convert CO at 270 ℃, and completely converts CH when CO is completely converted₄The selectivity reaches more than 90 percent.

The low-temperature high-activity nickel-based bimetallic methanation catalyst provided by the invention has a very long service life in the reaction of preparing methane from synthesis gas, in a service life test, the activity of the catalyst can not be reduced within 200h, the CO conversion rate can reach 100%, and the methane selectivity can reach more than 90%.

Drawings

FIG. 1 is a small angle XRD pattern of SBA-16-EG of an example vehicle according to the invention.

FIG. 2 is a HRTEM image of a low-temperature high-activity nickel-based bimetallic methanation catalyst of an embodiment of the invention.

Fig. 3 is a wide angle XRD pattern of the low-temperature high-activity nickel-based bimetallic methanation catalyst of the embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers. All percentages, ratios, proportions, or parts are by weight unless otherwise specified.

The weight volume percentage units in the present invention are well known to those skilled in the art and refer to, for example, the weight of solute in a 100 ml solution.

As used herein, "room temperature" means 15-30 deg.C, preferably 20-25 deg.C.

As used herein, "atmospheric pressure" means 0.1 MPa.

As used herein, mesoporous SiO, unless otherwise specified₂The synthesis method of the molecular sieve SBA-16-EG comprises the following steps: the hydrothermal synthesis temperature is 100 ℃ and the time is 24h, the drying is carried out at 100 ℃ for 12h, and the calcination is carried out at 550 ℃ for 5 h.

As used herein, the impregnation solvent is typically deionized water unless otherwise specified.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.

The reagents and materials used in the present invention are as follows:

nickel nitrate hexahydrate Ni (NO)₃)₂·6H₂O, analytically pure; nickel acetate tetrahydrate Ni (CH)₃COO)₂·4H₂O, analytically pure; iron nitrate nonahydrate Fe (NO)₃)₃·9H₂O, analytically pure; nickel acetate hexahydrate, analytically pure; cobalt (II) nitrate hexahydrate₃)₂·6H₂O, analytically pure; ethanol C₂H₅OH, analytically pure; ethylene glycol HOCH₂CH₂OH, analytically pure; the above reagents were purchased from Shanghai national drug group.