CN108568310B - Embedded microporous-mesoporous composite molecular sieve methanation catalyst and application thereof - Google Patents
Embedded microporous-mesoporous composite molecular sieve methanation catalyst and application thereof Download PDFInfo
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Abstract
The invention discloses an embedded microporous-mesoporous composite molecular sieve methanation catalyst and application thereof, and relates to the technical field of methanation catalysts. The composite molecular sieve ZSM-5/MCM-41 consisting of mesoporous molecular sieve MCM-41 and microporous molecular sieve ZSM-5 is used as a carrier, Ni is used as an active component, the active component Ni is embedded into a framework structure of the microporous-mesoporous composite molecular sieve by adopting an in-situ synthesis method, wherein the mass percent of Ni is 1-10 wt%, and the balance is the microporous-mesoporous molecular sieve ZSM-5/MCM-41. The invention has two structures of micropore and mesopore, has higher methane selectivity, has the advantages of low active component load, high activity, good high temperature resistance, good hydrothermal stability, long service life of the catalyst and the like, and has great industrial application prospect.
Description
Technical Field
The invention relates to the technical field of methanation catalysts, in particular to a microporous-mesoporous composite molecular sieve ZSM-5/MCM-41 methanation catalyst with an in-situ embedded active component and application thereof in SNG preparation.
Background
In recent years, with the implementation of sustainable development strategies and environmental protection policies in China, the demand for clean energy is increasing. As a high-quality and high-efficiency clean energy, natural gas is strongly pursued in the international market, and the consumption market is rapidly increased, so that the demand of China for natural gas is increasingly large, the supply and demand gaps are continuously expanded, and the dependence on the outside is gradually increased. The coal-based natural gas is used as a substitute and supplement for liquefied petroleum gas and natural gas, can optimize the structure of a coal deep-processing product, is environment-friendly, and is beneficial to relieving the problem of shortage of natural gas supply in China.
The preparation of methane from synthesis gas is one of the main reactions for the preparation of natural gas from coal, and belongs to a strong exothermic reaction. Because the CO concentration is higher in the reaction process, the temperature of a reaction system is increased due to a strong exothermic reaction, and the sintering deactivation of the active components of the catalyst is easily caused. Therefore, the reaction requires that the methanation catalyst can resist high temperature and have a long catalytic life while maintaining high activity, and the reaction generates water, so that the catalyst also needs to have good hydrothermal stability.
Among the existing industrial methanation catalysts, the supported Ni-based catalyst is most used because the Ni-based catalyst is relatively cheap, has high activity and has good selectivity for methane. For a high-temperature methanation reaction system, the selection of the carrier has great influence on the activity and the high-temperature resistance of the methanation catalyst. Therefore, the carrier is selected in consideration of not only its stability, inertness, mechanical strength, but also its dispersing effect on the active ingredient, its binding force with the active ingredient, and the like. The methanation carrier commonly used at present mainly comprises alumina, silica, kaolin, zirconia and the like, wherein Ni/Al2O3And Ni/ZrO2Has good catalytic activity, but NiO and Al2O3The interaction leads to difficulties in catalyst reduction, affecting its lifetime, Ni/ZrO2As the reaction proceeds, ZrO2The crystal phase of (a) will change from a tetragonal phase to a less reactive monoclinic phase and is expensive and therefore less useful for methanation reactions. The conventional supported methanation catalyst has the defects that the interaction between the active component and the carrier is weak, the catalyst cannot play a role of concerted catalysis with the active component, and the catalyst is easy to sinter and inactivate in the reaction process of strongly exothermic coal natural gas. Therefore, there is a need to find a catalyst support that can improve both the catalyst activity and the sintering resistance of the catalyst.
Mesoporous molecular sieve MCM-41 has the characteristics of hexagonal ordered arrangement of pore channels, uniform size, continuously adjustable pore diameter within the range of 2-10nm, large specific surface area and the like, and synthesizes MCM-41 with heteroatom doped in a framework structure, wherein non-four coordinated ions in the framework are as follows: al (Al)3+、Cu2+、Fe3+、Zn2+Etc., can be counterbalanced by protons or other transition metal ions to form catalytically active centers. Ni-MCM-41 catalyst prepared by in-situ synthesis method in CO2Reforming CH4The reaction shows good thermal stability. The mesoporous molecular sieve with metal doped in situ disclosed in Chinese patent application No. 201210457434.5 and its use are characterized by that it uses mesoporous molecular sieve MCM-41 as carrier, uses metal Ni as main active component, and makes them be doped into MCM-41 skeleton structure, and can be used in methanation reaction, and compared with supported catalyst, it possesses good high-temperature resistance, but its catalytic activity, in particular low-temperature catalytic activity still has to be raised, and its hydrothermal stability is not high.
The ZSM-5 zeolite contains ten-membered rings, and a basic structural unit consists of eight five-membered rings, so that the crystal structure is very stable. ZSM-5 is by far the highest thermal property of the known zeolites and is therefore particularly suitable for use in high temperature processes. ZSM-5 has high silicon-aluminum ratio, small surface charge density, good hydrophobicity, difficult carbon deposition and good hydrothermal stability, and is widely used as a catalyst of FCC. Meanwhile, ZSM-5 has strong acidity and adjustable acidity, and is widely applied to the field of acid catalysis; in addition, ZSM-5 has a unique pore structure, so that the catalyst becomes a good shape-selective catalyst. The novel catalytic material microporous-mesoporous ZSM-5/MCM-41 composite molecular sieve has the advantages of both ZSM-5 and MCM-41. Based on the above, it is especially necessary to design an embedded micro-mesoporous composite molecular sieve methanation catalyst and an application thereof in preparation of coal-based natural gas SNG.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an embedded microporous-mesoporous composite molecular sieve methanation catalyst and application thereof, wherein an active component Ni is embedded into a framework structure of a composite molecular sieve by adopting an in-situ synthesis method to prepare the microporous-mesoporous ZSM-5/MCM-41 composite molecular sieve methanation catalyst, the preparation method is simple, and the prepared catalyst has the advantages of good catalytic activity, good high-temperature resistance, good hydrothermal stability and long catalytic life and is easy to popularize and use.
In order to achieve the purpose, the invention is realized by the following technical scheme: an embedded microporous-mesoporous composite molecular sieve methanation catalyst takes composite molecular sieve ZSM-5/MCM-41 consisting of mesoporous molecular sieve MCM-41 and microporous molecular sieve ZSM-5 as a carrier, takes Ni as an active component, and adopts an in-situ synthesis method to embed the active component Ni into a framework structure of the microporous-mesoporous composite molecular sieve, wherein the content of Ni is 1-10 parts by mass and the balance is microporous-mesoporous molecular sieve ZSM-5/MCM-41 based on 100 parts by mass of the catalyst, and the mass ratio of the microporous molecular sieve ZSM-5 to the mesoporous molecular sieve MCM-41 is 1: 1-1: 5;
wherein, the in-situ synthesis method comprises the following steps:
(1) preparing a Ni salt solution;
(2) dispersing a ZSM-5 microporous molecular sieve in a NaOH solution, adding a template CTAB, stirring vigorously, adding a prepared Ni salt solution dropwise while adding a silicon source TEOS dropwise, stirring vigorously for a certain time, and transferring to a hydrothermal reaction kettle for crystallization;
(3) and cooling the crystallized stock solution to room temperature, performing suction filtration, washing to be neutral, drying in vacuum, and roasting to obtain the catalyst, wherein the Ni loading in the catalyst is 1-10 wt%. Preferably, the microporous molecular sieve ZSM-5 is a microporous molecular sieve carrier ZSM-5 with high specific surface area, and the specific surface area of the microporous molecular sieve carrier ZSM-5 is 300-500 m2/g，SiO2/Al2O3The molar ratio is 30-400; the mesoporous molecular sieve MCM-41 is a mesoporous molecular sieve MCM-41 with high specific surface area, and the specific surface area is 600-1500 m2The pore diameter is 3-10 nm.
Preferably, the active component Ni is Ni or Ni2O3Exist in the form of (1).
Preferably, the Ni salt is nickel sulfate, nickel chloride, nickel nitrate or nickel acetate; the solvent adopted by the Ni salt solution is deionized water and ethanol.
Preferably, the hydrothermal synthesis temperature is 80-150 ℃; the crystallization time is 2-168 h; the room temperature is 15-30 ℃; the drying temperature is 50-100 ℃, and the drying time is 2-10 h; the roasting temperature is 400-700 ℃, and the roasting time is 2-10 h.
Preferably, the hydrothermal synthesis temperature is 100-120 ℃; the crystallization time is 12-24 h; the room temperature is 20-25 ℃.
Application of embedded micropore-mesopore composite molecular sieve methanation catalyst in SNG preparation, wherein the atmosphere of the embedded micropore-mesopore composite molecular sieve methanation catalyst is H2A mixed gas of-CO with an airspeed of 3000-60000 h-1The pressure is 0.1 MPa-5.0 MPa, the reaction temperature is 200-700 ℃, and H in the mixed gas2The ratio of/CO is 1-4.
The invention has the beneficial effects that: the composite molecular sieve ZSM-5/MCM-41 consisting of mesoporous molecular sieve MCM-41 and microporous molecular sieve ZSM-5 is used as a carrier, an active component Ni is embedded into a framework structure of the composite molecular sieve by adopting an in-situ synthesis method, the microporous-mesoporous ZSM-5/MCM-41 composite molecular sieve methanation catalyst is prepared, and the prepared catalyst Ni has fine particles and good high temperature resistance. Compared with a single molecular sieve methanation catalyst, the ZSM-5/MCM-41 composite molecular sieve catalyst has excellent catalytic activity, high temperature resistance and hydrothermal stability in the application of SNG methanation reaction.
(1) The catalyst is a composite molecular sieve which is composed of a mesoporous molecular sieve MCM-41 with stable chemical properties and good thermal conductivity and a microporous molecular sieve ZSM-5 with high silica-alumina ratio, small surface charge density, good hydrophobicity, carbon deposition resistance and good hydrothermal stability and is used as a carrier, an active component Ni is embedded into a framework structure of the composite molecular sieve, the composite molecular sieve has good high temperature resistance, good hydrothermal stability and good catalytic life, the catalyst is calcined for 50 hours at the high temperature of 800 ℃ in a nitrogen atmosphere, the structure of the catalyst is not damaged, the catalytic activity is not obviously reduced, the catalyst is subjected to hydrothermal treatment for 10 hours at the temperature of 780 ℃, the structure of the catalyst is not obviously damaged, and the catalytic activity is not reduced.
(2) The catalyst shows excellent reaction activity and methane activity in the SNG reaction for preparing the natural gas from the coal, and shows good catalytic activity in the temperature range of 250-450 ℃, wherein the CO conversion rate reaches 100% and the methane selectivity reaches more than 99% in the temperature range of 300-400 ℃.
(3) The catalyst does not contain noble metal active components, the preparation method is simple and easy to implement, and the catalyst also has better catalytic activity at lower temperature, high cost performance and great industrial application prospect.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
The specific implementation mode adopts the following technical scheme: an embedded microporous-mesoporous composite molecular sieve methanation catalyst takes composite molecular sieve ZSM-5/MCM-41 consisting of mesoporous molecular sieve MCM-41 and microporous molecular sieve ZSM-5 as a carrier, takes Ni as an active component, and adopts an in-situ synthesis method to embed the active component Ni into a framework structure of the microporous-mesoporous composite molecular sieve, wherein the content of Ni is 1-10 parts by mass and the balance is microporous-mesoporous molecular sieve ZSM-5/MCM-41 based on 100 parts by mass of the catalyst, and the mass ratio of the microporous molecular sieve ZSM-5 to the mesoporous molecular sieve MCM-41 is 1: 1-1: 5.
it is worth noting that the microporous molecular sieve ZSM-5 is a microporous molecular sieve carrier ZSM-5 with a high specific surface area, and the specific surface area is 300-500 m2/g，SiO2/Al2O3The molar ratio is 30-400; the mesoporous molecular sieve MCM-41 is a mesoporous molecular sieve MCM-41 with high specific surface area, and the specific surface area is 600-1500 m2(ii)/g, the pore diameter is 3-10 nm; the active component Ni is Ni or Ni2O3Exist in the form of (1).
The preparation method of the embedded microporous-mesoporous composite molecular sieve methanation catalyst comprises the following steps:
(1) preparing a Ni salt solution;
(2) dispersing a ZSM-5 microporous molecular sieve in a NaOH solution, adding a template CTAB, stirring vigorously, adding a prepared Ni salt solution dropwise while adding a silicon source TEOS dropwise, stirring vigorously for a certain time, and transferring to a hydrothermal reaction kettle for crystallization;
(3) and cooling the crystallized stock solution to room temperature, performing suction filtration, washing to be neutral, drying in vacuum, and roasting to obtain the catalyst, wherein the Ni loading in the catalyst is 1-10 wt%.
It is noted that the Ni salt is nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate; the solvent adopted by the Ni salt solution is deionized water and ethanol; the hydrothermal synthesis temperature is 80-150 ℃, and preferably 100-120 ℃; the crystallization time is 2-168 hours, preferably 12-24 hours; the room temperature is 15-30 ℃, and preferably 20-25 ℃; the drying temperature is 50-100 ℃, and the drying time is 2-10 h; the roasting temperature is 400-700 ℃, and the roasting time is 2-10 h.
Application of embedded micropore-mesopore composite molecular sieve methanation catalyst in SNG preparation, wherein the atmosphere of the embedded micropore-mesopore composite molecular sieve methanation catalyst is H2A mixed gas of-CO with an airspeed of 3000-60000 h-1The pressure is 0.1 MPa-5.0 MPa, the reaction temperature is 200-700 ℃, and H in the mixed gas2The ratio of/CO is 1-4.
The specific implementation mode changes the traditional methanation catalyst that alumina is taken as a carrier, but a composite molecular sieve which is composed of a mesoporous molecular sieve MCM-41 with stable chemical properties and good heat conductivity and a microporous molecular sieve ZSM-5 with high silica-alumina ratio, small surface charge density, good hydrophobicity, difficult carbon deposition and good hydrothermal stability is taken as a carrier, and an in-situ synthesis method is adopted to embed an active component Ni into the framework structure of the composite molecular sieve, the microporous-mesoporous ZSM-5/MCM-41 composite molecular sieve methanation catalyst is prepared, the catalyst has two structures of micropores and mesopores, the methane selectivity is higher, the preparation method is simple, and the prepared catalyst has the advantages of good catalytic activity, low active component loading capacity, good high temperature resistance, good hydrothermal stability, long service life of the catalyst and the like. The catalyst is prepared at normal pressure, 300 ℃ and space velocity of 32000h-1Under the optimal conditions, the CO conversion rate reaches 100 percent, the methane selectivity reaches 99 percent, and the method has great industrial application prospect.
Example 1: the preparation method of the embedded microporous-mesoporous composite molecular sieve methanation catalyst comprises the following steps: weighing 1.6g of nickel nitrate hexahydrate, dissolving in 20ml of deionized water, and preparing into a nickel nitrate aqueous solution; dispersing 3.3g of ZSM-5 molecular sieveIn NaOH solution, heating the solution to 40 ℃, adding a certain amount of template agent (cetyl trimethyl ammonium bromide) under vigorous stirring, slowly dropwise adding nickel nitrate aqueous solution and silicon source (tetraethoxysilane) into the solution, adjusting the pH value of the solution to 11, wherein the molar ratio of each substance in the solution is as follows: 1.0 ZSM-5: 0.12 Ni: 0.12 CTAB: 1.0 TEOS: 0.2 NaOH: 100H2And O. And violently stirring and aging the mixed solution for 2 hours, then transferring the mixed solution into a hydrothermal reaction kettle, crystallizing the mixed solution for 72 hours at 100 ℃, rapidly cooling the mixed solution to room temperature, filtering and washing the mixed solution to be neutral, drying the mixed solution overnight at 100 ℃, calcining the dried mixed solution for 6 hours at 550 ℃, and removing a template agent to obtain the 5 wt% Ni-ZSM-5/MCM-41 composite molecular sieve methanation catalyst which is marked as catalyst A.
Example 2: the preparation method of the embedded microporous-mesoporous composite molecular sieve methanation catalyst comprises the following steps: weighing 3.2g of nickel nitrate hexahydrate, dissolving in 20ml of deionized water, and preparing into a nickel nitrate aqueous solution; dispersing 3.3g of ZSM-5 molecular sieve in NaOH solution, heating the solution to 40 ℃, adding a certain amount of template agent (cetyl trimethyl ammonium bromide) under vigorous stirring, slowly dropwise adding a nickel nitrate aqueous solution and a silicon source (tetraethoxysilane) into the solution, adjusting the pH value of the solution to 11, wherein the molar ratio of each substance in the solution is as follows: 1.0 ZSM-5: 0.12 Ni: 0.12 CTAB: 1.0 TEOS: 0.2 NaOH: 100H2And O. And violently stirring and aging the mixed solution for 2 hours, then transferring the mixed solution into a hydrothermal reaction kettle, crystallizing the mixed solution for 72 hours at 100 ℃, rapidly cooling the mixed solution to room temperature, filtering and washing the mixed solution to be neutral, drying the mixed solution overnight at 100 ℃, calcining the dried mixed solution for 6 hours at 550 ℃, and removing a template agent to obtain the 10 wt% Ni-ZSM-5/MCM-41 composite molecular sieve methanation catalyst which is marked as catalyst B.
Comparative example 1: 0.8g of nickel nitrate hexahydrate is weighed and dissolved in 20ml of deionized water to prepare an aqueous nickel nitrate solution. Dispersing a certain amount of template agent (hexadecyl trimethyl ammonium bromide) in NaOH solution, heating the solution to 40 ℃, slowly dropwise adding nickel nitrate aqueous solution and silicon source (tetraethoxysilane) into the solution, adjusting the pH value of the solution to 11, and adjusting the molar ratio of the substances in the solution to be: 0.06 Ni: 0.12 CTAB: 1.0 TEOS: 0.2 NaOH: 100H2And O. The mixed solution is stirred vigorously and aged for 2 hours, then transferred into a hydrothermal reaction kettle, crystallized for 72 hours at 100 ℃, quenched to room temperature, filtered, washed to be neutral, dried at 100 ℃ overnight, calcined at 550 ℃ for 6 hoursAnd removing the template agent to obtain the 5 wt% Ni-MCM-41 monomolecular sieve methanation catalyst which is marked as catalyst a.
Comparative example 2: 1.6g of nickel nitrate hexahydrate is weighed and dissolved in 20ml of deionized water to prepare an aqueous nickel nitrate solution. Dispersing a certain amount of template agent (hexadecyl trimethyl ammonium bromide) in NaOH solution, heating the solution to 40 ℃, slowly dropwise adding nickel nitrate aqueous solution and silicon source (tetraethoxysilane) into the solution, adjusting the pH value of the solution to 11, and adjusting the molar ratio of the substances in the solution to be: 0.06 Ni: 0.12 CTAB: 1.0 TEOS: 0.2 NaOH: 100H2And O. And violently stirring and aging the mixed solution for 2 hours, then transferring the mixed solution into a hydrothermal reaction kettle, crystallizing the mixed solution for 72 hours at 100 ℃, rapidly cooling the mixed solution to room temperature, filtering and washing the mixed solution to be neutral, drying the mixed solution overnight at 100 ℃, calcining the dried mixed solution for 6 hours at 550 ℃, and removing a template agent to obtain a 10 wt% Ni-MCM-41 monomolecular sieve methanation catalyst which is marked as catalyst b.
Comparative example 3: weighing 0.5g of nickel nitrate hexahydrate, dissolving in 20ml of deionized water, and preparing into a nickel nitrate aqueous solution; then weighing 1g of mesoporous molecular sieve MCM-41, and soaking the molecular sieve MCM-41 in a nickel nitrate aqueous solution at normal temperature by adopting an isometric soaking method. And standing the mixture for 8 hours at room temperature after stirring, drying the mixture for 6 hours at 100 ℃, and roasting the dried mixture for 6 hours at 550 ℃ to obtain the supported methanation catalyst with the nickel loading of 10 wt%, namely 10 wt% Ni/MCM-41, which is marked as catalyst c.
Example 3: this example illustrates the application of the methanation catalysts prepared in examples 1 to 2 and comparative examples 1 to 3 in methanation reaction of high concentration CO.
The catalysts prepared in examples 1-2 and comparative examples 1-3 were packed in a fixed bed microreactor having an inner diameter of 8mm, and N was used before the reaction2Purging the reaction system to remove air, reducing the reaction system with high-purity hydrogen for 2h at 600 ℃, then reducing the temperature to 250 ℃ under the protection of nitrogen, testing the catalytic activity of the catalyst in the reaction atmosphere, then calcining the catalyst for 10h at 800 ℃ under the atmosphere of nitrogen, reducing the reaction temperature to 250 ℃, and inspecting the catalytic activity again. Gas products obtained by the reaction are analyzed on line by gas chromatography, and the raw material gas composition and the catalytic reaction conditions are as follows:
the raw material gas composition is as follows: CO: 30% of H2：90％，N2：10％；
Catalyst loading: 0.1 g;
reaction temperature: 250 ℃;
reaction pressure: 2 MPa;
the reaction space velocity: 12000h-1；
The composition of raw material gas and catalytic reaction conditions applicable to the catalyst of the invention can also be as follows: the volume space velocity of the synthesis gas is 3000-60000 h-1The pressure is 0.1-5.0 Mpa, the temperature is 200-700 ℃, and H2The ratio of/CO is 1-4.
CO conversion and CH were determined and calculated as follows4The selectivity, results are listed in table 1:
conversion rate of CO: cCO(1-amount of CO contained in product/amount of CO contained in raw material gas). times.100%
CH4And (3) selectivity: sCH4Is converted to CH4CO amount of (2)/amount of CO conversion) × 100%
Example 4: this example illustrates the hydrothermal stability of the methanation catalysts prepared in examples 1 to 2 and comparative examples 1 to 3 in the methanation reaction of high concentration CO.
The catalysts prepared in examples 1-2 and comparative examples 1-3 were packed in a fixed bed microreactor having an inner diameter of 8mm, and N was used before the reaction2Purging the reaction system to remove air, reducing with high-purity hydrogen at 600 deg.C for 2h, reducing to 250 deg.C under nitrogen protection, testing its catalytic activity in the reaction atmosphere, and introducing water vapor with partial pressure of 4.5 x 104Pa, nitrogen flow 30ml/min, temperature rising to 780 ℃ hydrothermal aging for 10h, switching to reaction atmosphere, cooling to 250 ℃, and investigating the catalytic activity again. The gas product obtained by the reaction was analyzed on-line by gas chromatography, and the feed gas composition and the catalytic reaction conditions were the same as in example 3, and the results are shown in table 1.
TABLE 1 CO conversion and CH for each catalyst4Selective comparison table
| Catalyst and process for preparing same | CO conversion (%) | CH4 Selectivity (%) | Reduction in high-temperature calcination Activity (%) | Decrease in hydrothermal aging Activity (%) |
| Agent A | 100.0 | 97.5 | 0.0 | 0.0 |
| Catalyst B | 100.0 | 99.9 | 0.0 | 0.0 |
| Catalyst a | 90.2 | 92.4 | 0.0 | 12.4 |
| Catalyst b | 95.3 | 95.1 | 0.0 | 15.8 |
| Catalyst c | 93.2 | 94.3 | 20.5 | 42.6 |
As can be seen from Table 1, the catalyst A and the catalyst a are compared, and the catalytic activity of the embedded composite molecular sieve methanation catalyst is obviously superior to that of the embedded single molecular sieve methanation catalyst, and the CO conversion rate and the CH are obviously superior to those of the embedded single molecular sieve methanation catalyst4The selectivity is respectively improved by 9.8 percent and 5.1 percent; meanwhile, compared with the embedded single molecular sieve methanation catalyst, the hydrothermal stability of the embedded composite molecular sieve methanation catalyst is obviously improved, the catalytic activity of the composite molecular sieve catalyst A is not reduced after hydrothermal aging, and the catalytic activity of the single molecular sieve methanation catalyst is reduced by 12.4%. Comparing the catalyst B, the catalyst B and the catalyst c, the catalyst B, the catalyst B and the catalyst c show that compared with the embedded monomolecular sieve methanation catalyst, the embedded composite monomolecular sieve methanation catalyst is obviously improved in the aspects of catalytic activity and hydrothermal stability; compared with a supported monomolecular sieve methanation catalyst, the embedded composite monomolecular sieve methanation catalyst is obviously improved in the aspects of catalytic activity, high temperature resistance and hydrothermal stability.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. An embedded microporous-mesoporous composite molecular sieve methanation catalyst is characterized in that a composite molecular sieve ZSM-5/MCM-41 composed of a mesoporous molecular sieve MCM-41 and a mesoporous molecular sieve ZSM-5 is used as a carrier, Ni is used as an active component, and the active component Ni is embedded into a framework structure of the microporous-mesoporous composite molecular sieve by an in-situ synthesis method, wherein the Ni content is 1-10 parts by mass and the balance is the microporous-mesoporous molecular sieve ZSM-5/MCM-41 based on 100 parts by mass of the catalyst, and the mass ratio of the microporous molecular sieve ZSM-5 to the mesoporous molecular sieve MCM-41 is 1: 1-1: 5;
wherein, the in-situ synthesis method comprises the following steps:
(1) preparing a Ni salt solution;
(2) dispersing a ZSM-5 microporous molecular sieve in a NaOH solution, adding a template CTAB, stirring vigorously, adding a prepared Ni salt solution dropwise while adding a silicon source TEOS dropwise, stirring vigorously for a certain time, and transferring to a hydrothermal reaction kettle for crystallization;
(3) and cooling the crystallized stock solution to room temperature, performing suction filtration, washing to be neutral, drying in vacuum, and roasting to obtain the catalyst, wherein the Ni loading in the catalyst is 1-10 wt%.
2. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 1, wherein the microporous molecular sieve ZSM-5 is a microporous molecular sieve carrier ZSM-5 with a high specific surface area, and the specific surface area is 300-500 m2/g，SiO2/Al2O3The molar ratio is 30-400.
3. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 1, wherein the mesoporous molecular sieve MCM-41 is a mesoporous molecular sieve MCM-41 with a high specific surface area, and the specific surface area is 600-1500 m2The pore diameter is 3-10 nm.
4. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 1, wherein the active component Ni is Ni or Ni2O3Exist in the form of (1).
5. The embedded microporous-mesoporous composite molecular sieve methanation catalyst of claim 1, wherein the Ni salt is nickel sulfate, nickel chloride, nickel nitrate, or nickel acetate.
6. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 1, wherein solvents adopted by the Ni salt solution are deionized water and ethanol.
7. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 5, wherein the hydrothermal synthesis temperature is 80-150 ℃; the crystallization time is 2-168 h; the room temperature is 15-30 ℃; the drying temperature is 50-100 ℃, and the drying time is 2-10 h; the roasting temperature is 400-700 ℃, and the roasting time is 2-10 h.
8. The embedded microporous-mesoporous composite molecular sieve methanation catalyst according to claim 7, wherein the hydrothermal synthesis temperature is 100-120 ℃; the crystallization time is 12-24 h; the room temperature is 20-25 ℃.
9. The application of the embedded microporous-mesoporous composite molecular sieve methanation catalyst in the preparation of SNG (synthetic natural gas) based on any one of claims 1 to 8, wherein the embedded microporous-mesoporous composite molecular sieve methanation catalyst is in an atmosphere of H2A mixed gas of-CO with an airspeed of 3000-60000 h-1The pressure is 0.1 MPa-5.0 MPa, the reaction temperature is 200-700 ℃, and H in the mixed gas2The ratio of/CO is 1-4.
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| CN102886272A (en) * | 2012-04-26 | 2013-01-23 | 华东理工大学 | Supported catalyst, preparation method and application thereof |
| CN104549476A (en) * | 2015-01-12 | 2015-04-29 | 天津大学 | Nickel metal loaded micro-mesoporous molecular sieve catalyst precursor and preparation method and application of nickel metal loaded micro-mesoporous molecular sieve catalyst precursor |
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| CN102886272A (en) * | 2012-04-26 | 2013-01-23 | 华东理工大学 | Supported catalyst, preparation method and application thereof |
| CN104549476A (en) * | 2015-01-12 | 2015-04-29 | 天津大学 | Nickel metal loaded micro-mesoporous molecular sieve catalyst precursor and preparation method and application of nickel metal loaded micro-mesoporous molecular sieve catalyst precursor |
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| 基于介孔SiO2的Ni基甲烷化催化剂的制备、表征及催化性能研究;张加赢;《中国博士学位论文全文数据库 工程科技Ⅰ辑》;20140615(第6期);第4.1节，第4.3.1.2节 * |
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