Titanium silicalite molecular sieve packaged nickel-based nano-alloy catalyst as well as preparation method and application thereof

Abstract

The invention relates to a titanium silicalite molecular sieve packaged nickel-based nano-alloy catalyst as well as a preparation method and application thereof. The catalyst comprises a carrier and a nano-alloy packaged in the carrier, the carrier comprises a titanium silicalite molecular sieve; the metal in the nano-alloy comprises nickel and a second metal, and the second metal comprises a combination of at least three of cobalt, copper, zinc or manganese. According to the titanium silicalite molecular sieve packaged nickel-based nano-alloy catalyst for the methane dry reforming reaction, the titanium silicalite molecular sieve shell provides heat insulation and infrared shielding to improve the photothermal conversion efficiency, the position of the nickel-based nano-alloy is limited in space, and the catalyst has high activity and outstanding carbon deposition resistance and thermal stability at the same time; and efficient photo-thermal catalysis of methane dry reforming reaction at low temperature can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic chemistry, and particularly relates to a titanium-silicon molecular sieve encapsulated nickel-based nano-alloy catalyst, a preparation method and use thereof. BACKGROUND

[0002] Methane dry reforming reaction (CH4+CO2→2H2+2CO) is considered as one of the key technologies for realizing the "double carbon" strategic goal and building a circular carbon economy, and has broad application prospects, because it can simultaneously convert two greenhouse gases (CH4 and CO2) into more industrially valuable syngas (CO and H2).

[0003] A suitable catalyst is the key to the industrial application of methane carbon dioxide reforming. Although noble metal-based catalysts have excellent catalytic activity, they are expensive and need to find more affordable transition metals as substitutes. Nickel-based catalysts are closest to noble metals in performance, but due to the low Tamman temperature of nickel, the methane reforming reaction is limited by thermodynamics and needs to be above 600℃ to be spontaneous, in addition, carbon species generated by methane cracking (CH4→C+2H2) and Boudouard reaction (2CO→C+CO2) at high temperatures will irreversibly deposit on the surface and pores of the catalyst.

[0004] The prior art CN109718807A discloses a methane dry reforming catalyst, a preparation method and application thereof, and a method for preparing syngas by methane dry reforming. The preparation method of the catalyst comprises: (1) impregnating a carrier with a solution containing a soluble compound of a first active metal component, then performing first drying and first calcination to obtain a semi-finished catalyst, wherein the solution also contains a surfactant; (2) activating the semi-finished catalyst obtained in step (1) in an atmosphere containing hydrogen to obtain an activated catalyst; (3) under displacement reaction conditions, contacting the activated catalyst obtained in step (2), a soluble compound of a second active metal component, and a dispersing agent, then performing second drying and second calcination; the first active metal component is cobalt and / or nickel, and the second active metal component is selected from at least one of noble metals; the carrier is MgO-Al2O3; the amount and contacting conditions of the activated catalyst and the soluble compound of the second active metal component are such that the molar ratio of the second active metal component to the first active metal component in the prepared catalyst is 0.0037-0.01:1.

[0005] In the synthesis method of the catalyst, the active component of the catalyst is generally supported on high specific surface area materials such as aluminum oxide and silicon dioxide by impregnation to improve the dispersion of the active component. However, for the catalyst prepared by impregnation, the active component is supported on the surface of the carrier, and the interaction with the carrier is not strong, which easily leads to migration and sintering of the active component at high temperature and deactivation. And by loading nickel on a reducing carrier to enhance metal-support interaction (MSI), the nanoparticles are fixed and their migration and agglomeration are inhibited. However, since the active nickel nanoparticles are exposed, the catalyst surface is still prone to carbon deposition, leading to a decrease in catalyst performance.

[0006] The prior art has the defects of low activity, poor stability and poor carbon deposition resistance of the methane dry reforming catalyst, and therefore, it has become an urgent problem to develop a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst. SUMMARY

[0007] To solve the above technical problems, the present application provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst and a preparation method thereof. The catalyst uses titanium silicalite as a carrier, and nanoscale alloy particles are encapsulated in the titanium silicalite. The metals in the nanoscale alloy include nickel and a second metal, and the second metal includes a combination of at least three of cobalt, copper, zinc or manganese. The catalyst includes a carrier and nanoscale alloy encapsulated in the carrier. The titanium silicalite shell improves the photo-thermal conversion efficiency by providing thermal insulation and infrared shielding, and spatially limits the position of the nickel-based nanoscale alloy. The nanoparticles with high-entropy effect can promote the adsorption and activation of intermediate substances, thereby achieving high yield and long-term stability.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which includes a carrier and nanoscale alloy encapsulated in the carrier. The carrier includes titanium silicalite. The metals in the nanoscale alloy include nickel and a second metal, and the second metal includes a combination of at least three of cobalt, copper, zinc or manganese.

[0010] The present application takes titanium silicalite molecular sieve as a carrier, and encapsulates a nano-alloy in the carrier. The metal in the nano-alloy includes nickel and a second metal, and the second metal includes a combination of at least three of cobalt, copper, zinc or manganese. The titanium silicalite molecular sieve shell improves the light-heat conversion efficiency by providing thermal insulation and infrared shielding, and spatially limits the position of the nickel-based nano-alloy. The core lattice distortion and cocktail effect of the high-entropy nano-alloy optimize the adsorption and intermediate adsorption energy, and expose more active sites to promote the adsorption and activation of intermediate substances. This structure can inhibit particle migration and sintering, and improve the thermodynamic and kinetic stability. Under light, the alloy nanoparticles can also adjust the surface plasmon resonance to the ultraviolet-visible light region, as an ideal photo-thermal catalyst, which can drive methane reforming under milder conditions, effectively utilize solar energy, reduce carbon deposition and sintering, and synergistically achieve high yield and long-term stability.

[0011] In the present application, the second metal includes a combination of at least three of cobalt, copper, zinc or manganese, wherein typical but non-limiting combinations include: a combination of cobalt, copper and zinc, a combination of cobalt, copper and manganese, a combination of copper, zinc and manganese, a combination of cobalt, copper, zinc and manganese, and preferably a combination of cobalt, copper, zinc and manganese.

[0012] As a preferred technical solution of the present application, the nano-alloy exists in the form of alloy particles.

[0013] Preferably, the particle size of the alloy particles is 2-7.5 nm, for example, it can be 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm or 7.5 nm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0014] Preferably, the mass percentage of any metal in the catalyst is independently 0.1-5 wt%, for example, it can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt% or 5 wt%, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0015] Preferably, the molar ratio of any one of the second metals to nickel is independently (1-4):(5-10), for example, the molar ratio of any one of the second metals to nickel can be 1:5, 1:7, 1:10, 3:5, 3:7, 3:10, 4:5, 4:7 or 4:10, but not limited to the listed values, other values not listed in the above range are also applicable. As preferred, when the second metal elements are cobalt, copper, zinc and manganese, the molar ratio of cobalt, copper, zinc, manganese to nickel is 3:3:2:1:6, when the second metal is a combination of cobalt, copper and zinc, the molar ratio of cobalt, copper, zinc to nickel is 3:3:2:6, when the second metal is a combination of cobalt, copper and manganese, the molar ratio of cobalt, copper, manganese to nickel is 3:3:1:6, and when the second metal is a combination of cobalt, zinc and manganese, the molar ratio of cobalt, zinc, manganese to nickel is 3:2:1:6.

[0016] In a second aspect, the present application provides a preparation method of a titanium silicalite encapsulated nickel-based nanometer alloy catalyst, which comprises the following steps:

[0017] (1) mixing a solution of an organic template agent and water with a silicon source to obtain a mixture A;

[0018] (2) mixing a solution of a titanium source and an organic solvent with the mixture A to obtain a mixture B;

[0019] (3) dissolving a nickel salt and a second metal salt in an organic amine complexing agent to obtain a metal salt precursor, and mixing the metal salt precursor with the mixture B to obtain a mixture C;

[0020] (4) hydrothermally reacting the mixture C to obtain a solid-phase product through solid-liquid separation;

[0021] (5) sequentially washing, drying, calcining and reducing the solid-phase product to obtain the titanium silicalite encapsulated nickel-based nanometer alloy catalyst.

[0022] The present application synthesizes a titanium silicalite encapsulated nickel-based nanometer alloy catalyst by one-step hydrothermal method, and the metal precursor is reduced and nucleated to form alloy nanoparticles while the molecular sieve crystal grows, so as to be in-situ wrapped in the pores of the molecular sieve.

[0023] As a preferred technical solution of the present application, the organic template agent in step (1) comprises tetrapropylammonium hydroxide or tetraethylammonium hydroxide, and is preferably tetrapropylammonium hydroxide.

[0024] Preferably, the silicon source in step (1) comprises any one of tetraethyl orthosilicate, silica sol or water glass, and is preferably tetraethyl orthosilicate.

[0025] Preferably, the titanium source in step (2) comprises any one of tetrabutyl titanate, tetraethyl titanate or tetraisopropyl titanate, preferably tetrabutyl titanate.

[0026] Preferably, the organic solvent in step (2) comprises isopropyl alcohol.

[0027] Preferably, the organic amine complexing agent in step (3) comprises any one of ethylenediamine, ethylenediaminetetraacetic acid or diethylamine, preferably ethylenediamine.

[0028] In the present application, the organic amine complexing agent is used as a ligand to chelate metal cations and interacts with the structure-directing agent, ensuring high dispersion of nanoparticles in the molecular sieve framework.

[0029] Preferably, the second metal salt in step (3) comprises any one of nitrate, chloride or sulfate of cobalt, copper, zinc or manganese, for example, can be nitrate of cobalt, chloride of cobalt, sulfate of cobalt, nitrate of copper, chloride of copper, sulfate of copper, nitrate of zinc, chloride of zinc, sulfate of zinc, nitrate of manganese, chloride of manganese, sulfate of manganese, and the nickel salt in step (3) comprises any one of nitrate, chloride or sulfate of nickel.

[0030] As a preferred technical solution of the present application, the mass ratio of the organic template agent, water and silicon source in step (1) is (0.01-0.015):(25-27):(8-10), for example, can be 0.01:25:8, 0.01:26:8, 0.01:27:8, 0.01:25:9, 0.01:26:9, 0.01:27:9, 0.01:25:10, 0.01:26:10, 0.01:27:10, 0.015:25:8, 0.015:26:8, 0.015:27:8, 0.015:25:9, 0.015:26:9, 0.015:27:9, 0.015:25:10, 0.015:26:10 or 0.015:27:10, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0031] Preferably, the volume ratio of the titanium source and the organic solvent in step (2) is (0.2-0.3):(2-3), for example, can be 0.2:2, 0.2:3, 0.25:2, 0.25:3, 0.3:2 or 0.3:3, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0032] Preferably, the molar ratio of each of the metal elements in the second metal salt to the nickel element in the nickel salt in step (3) is independently (1-4):(5-10), for example, the molar ratio of each of the metal elements in the second metal salt to the nickel element in the nickel salt can be 1:5, 1:7, 1:10, 3:5, 3:7, 3:10, 4:5, 4:7 or 4:10, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0033] Preferably, the concentration of each metal ion in the metal salt precursor in step (3) is independently 0.2-1 mol / L, for example, it can be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0034] As a preferred technical solution of the present application, the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and the stirring speed is independently 200-500 r / min, for example, it can be 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min or 500 r / min, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0035] Preferably, the time for the first mixing in step (1) is 6-7 h, for example, it can be 6 h, 6.2 h, 6.4 h, 6.6 h, 6.8 h or 7 h, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0036] Preferably, the time for the second mixing in step (2) is 3-4 h, for example, it can be 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h or 4 h, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0037] Preferably, the time for the third mixing in step (3) is 0.5-1 h, for example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0038] As a preferred technical solution of the present application, the temperature of the hydrothermal reaction in step (4) is 150-170℃, for example, it can be 150℃, 155℃, 160℃, 165℃ or 170℃, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0039] In the present application, too high a hydrothermal temperature can cause the molecular sieve framework to partially desiliconize and even collapse, destroy its regular microporous structure, and significantly reduce the specific surface area, and the crystal growth is too fast and violent, which can cause the internal nickel-based high-entropy alloy nanoparticles to be "extruded" or exposed on the outer surface of the molecular sieve, losing the confinement and protection of encapsulation, and too low a temperature cannot form a complete and highly crystalline titanium silicate molecular sieve framework, and titanium cannot be effectively incorporated into the molecular sieve framework, so the hydrothermal temperature needs to be limited to a certain range.

[0040] Preferably, the pressure of the hydrothermal reaction in step (4) is 1-5MPa, for example, it can be 1MPa, 2MPa, 3MPa, 4MPa or 5MPa, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0041] Preferably, the time of the hydrothermal reaction in step (4) is 72-96h, for example, it can be 72h, 74h, 76h, 78h, 80h, 82h, 84h, 86h, 88h, 90h, 92h, 94h or 96h, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0042] In the present application, too long a hydrothermal time can cause "over-crystallization", which can cause the molecular sieve framework to partially desiliconize and even collapse, destroy its regular microporous structure, and too short a hydrothermal time cannot completely convert the titanium silicate molecular sieve precursor into crystals, resulting in a very thin and incomplete molecular sieve shell, high porosity and poor mechanical strength, which cannot effectively constrain the internal nano-alloy, and the nano-alloy will quickly deactivate due to sintering and carbon deposition, resulting in poor stability.

[0043] As a preferred technical solution of the present application, the temperature of the drying treatment in step (5) is 60-80℃, for example, it can be 60℃, 65℃, 70℃, 75℃ or 80℃, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0044] Preferably, the time of the drying treatment in step (5) is 12-24h, for example, it can be 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0045] Preferably, the temperature of the calcination treatment in step (5) is 500-600°C, for example, it can be 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0046] Preferably, the time of the calcination treatment in step (5) is 8-10h, for example, it can be 8h, 8.5h, 9h, 9.5h or 10h, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0047] Preferably, the temperature of the reduction treatment in step (5) is 600-700°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C or 700°C, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0048] Preferably, the time of the reduction treatment in step (5) is 1-2h, for example, it can be 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0049] Preferably, the atmosphere of the reduction treatment in step (5) comprises hydrogen.

[0050] Preferably, the flow rate of the hydrogen is 5-10mL / min, for example, it can be 5mL / min, 6mL / min, 7mL / min, 8mL / min, 9mL / min or 10mL / min, but not only limited to the listed values, other values not listed in the above range are also applicable.

[0051] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0052] (1) mixing a mixed solution of an organic template agent and water with a silicon source for 6-7h to obtain a mixture A; wherein the organic template agent comprises tetrapropylammonium hydroxide or tetraethylammonium hydroxide, the silicon source comprises any one of tetraethyl orthosilicate, silica sol or water glass, and the mass ratio of the organic template agent, water and silicon source is (10-15):(25-27):(8-10);

[0053] (2) mixing a mixed solution of a titanium source and an organic solvent with the mixture A for 3-4h to obtain a mixture B; wherein the titanium source comprises any one of tetrabutyl titanate, tetraethyl titanate or tetraisopropyl titanate, the organic solvent comprises isopropyl alcohol, and the volume ratio of the titanium source and the organic solvent is (0.2-0.3):(2-3);

[0054] (3) dissolving nickel salt and second metal salt in organic amine complexing agent to obtain metal salt precursor, mixing the metal salt precursor with the mixture B for 0.5-1h to obtain mixture C; wherein, the organic amine complexing agent includes any one of ethylenediamine, ethylenediaminetetraacetic acid or diethylamine, the second metal salt includes any one of nitrate, chloride or sulfate of cobalt, copper, zinc or manganese, the nickel salt includes any one of nitrate, chloride or sulfate of nickel, the molar ratio of any metal element in the second metal salt to nickel element in the nickel salt is independently (1-4):(5-10), the concentration of each metal ion in the metal salt precursor is independently 0.2-1mol / L, the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and the stirring speed is independently 200-500r / min;

[0055] (4) hydrothermally reacting the mixture C at 150-170℃, 1-5MPa for 72-96h to obtain solid phase product through solid-liquid separation;

[0056] (5) sequentially washing the solid phase product, drying at 60-80℃ for 12-24h, calcining at 500-600℃ for 8-10h, reducing at 600-700℃ for 1-2h, wherein the reducing atmosphere includes hydrogen, and the flow rate of hydrogen is 5-10mL / min, to obtain the titanium silicalite encapsulated nickel-based nano-alloy catalyst.

[0057] In a third aspect, the present application provides a use of the titanium silicalite encapsulated nickel-based nano-alloy catalyst, wherein the catalyst is used in a methane dry reforming reaction.

[0058] Preferably, the conditions of the methane dry reforming reaction include: the reaction space velocity is 3000-5000mL / (h·g), for example, it can be 3000mL / (h·g), 3500mL / (h·g), 4000mL / (h·g), 4500mL / (h·g) or 5000mL / (h·g), the reaction temperature is 200-450℃, for example, it can be 200℃, 250℃, 300℃, 350℃, 400℃ or 450℃, the light intensity of the reaction is 1.5-2W / cm 2 , for example, it can be 1.5W / cm 2 , 1.6W / cm 2 , 1.7W / cm 2 , 1.8W / cm 2 , 1.9W / cm 2 or 2W / cm 2but are not limited to the recited numerical values, other non-recited numerical values within the above numerical range are also applicable.

[0059] Compared with the prior art, the present application has at least the following beneficial effects:

[0060] The titanium silicalite encapsulated nickel-based nanometer alloy catalyst provided by the present application can improve the photo-thermal conversion efficiency by providing thermal insulation and infrared shielding through the titanium silicalite shell, and can limit the position of the nickel-based nanometer alloy in space, and the nanoparticles with high-entropy effect can promote the adsorption and activation of intermediate substances, thereby achieving high yield and long-term stability. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is the XRD spectrum of the catalyst obtained in Example 1 and Comparative Example 4 and the titanium silicalite carrier;

[0062] Figure 2 is the SEM image of the catalyst obtained in Example 1 and Comparative Example 4 and the titanium silicalite carrier;

[0063] Figure 3 is the TEM image and particle size distribution graph of the nanometer alloy particles in the catalyst obtained in Example 1. DETAILED DESCRIPTION

[0064] The technical solutions of the present application will be further described below in combination with the drawings and through specific embodiments. However, the following examples are only simple examples of the present application, and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0065] Example 1

[0066] The present embodiment provides a titanium silicalite encapsulated nickel-based nanometer alloy catalyst, which comprises a carrier and a nanometer alloy encapsulated inside the carrier, and the carrier comprises titanium silicalite;

[0067] The metal in the nanometer alloy comprises nickel and a second metal, and the second metal is a combination of cobalt, copper, zinc and manganese, and the molar ratio of cobalt, copper, zinc, manganese and nickel is 3:3:2:1:6, and the nanometer alloy exists in the form of alloy particles, and the particle size of the alloy particles is 2-7.5nm. Figure 3 It can be seen that the particle size of the nanometer alloy particles is 2-7.5nm, the D50 particle size is about 3.79nm, and the mass percentage of the five metals of nickel, cobalt, copper, zinc and manganese in the catalyst is 0.84wt%, 0.42wt%, 0.42wt%, 0.28wt% and 0.14wt% respectively.

[0068] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, and the preparation method comprises the following steps:

[0069] (1) a first mixing of a mixed solution of 13 g of tetrapropylammonium hydroxide and 25.2 g of water with 8.32 g of tetraethyl silicate for 6 h to obtain a mixture A;

[0070] (2) a second mixing of a mixed solution of 0.272 g of tetrabutyl titanate and 2 mL of isopropyl alcohol with the mixture A for 3 h to obtain a mixture B;

[0071] (3) dissolving nitrate salts of nickel, cobalt, copper, zinc and manganese in ethylenediamine to obtain a metal salt precursor, and third mixing of the metal salt precursor with the mixture B for 1 h to obtain a mixture C; wherein a molar ratio of cobalt, copper, zinc, manganese to nickel in the metal salt precursor is 3:3:2:1:6, and a concentration of each metal ion in the metal salt precursor is independently 0.5 mol / L, a volume of the metal salt precursor is 1800 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and a stirring speed is independently 200 r / min;

[0072] (4) hydrothermal reaction of the mixture C at 170 ℃ and 3 MPa for 96 h to obtain a solid-phase product through solid-liquid separation;

[0073] (5) sequentially washing, drying at 60 ℃ for 24 h, calcining at 550 ℃ for 8 h and hydrogen reduction at 700 ℃ for 1 h of the solid-phase product to prepare the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst.

[0074] Embodiment 2

[0075] The embodiment provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which comprises a carrier and a nanoscale alloy encapsulated in the carrier, and the carrier comprises titanium silicalite.

[0076] The metal in the nanoscale alloy comprises nickel and a second metal, the second metal is a combination of cobalt, copper, zinc and manganese, a molar ratio of cobalt, copper, zinc, manganese to nickel is 1:1:3:3:5, the nanoscale alloy exists in the form of alloy particles, a D50 particle size of the alloy particles is 4.0 nm, and a mass percentage of nickel, cobalt, copper, zinc and manganese in the catalyst is respectively 0.81 wt%, 0.16 wt%, 0.16 wt%, 0.48 wt% and 0.48 wt%.

[0077] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanometer alloy catalyst, and the preparation method comprises the following steps:

[0078] (1) a first mixing of a mixed solution of 10 g of tetrapropyl ammonium hydroxide and 26 g of water with 9.1 g of tetraethyl silicate for 6.5 h to obtain a mixture A;

[0079] (2) a second mixing of a mixed solution of 0.21 g of tetrabutyl titanate and 2.5 mL of isopropyl alcohol with the mixture A for 3.5 h to obtain a mixture B;

[0080] (3) dissolving nitrate salts of nickel, cobalt, copper, zinc and manganese in ethylenediamine to obtain a metal salt precursor, and third mixing the metal salt precursor with the mixture B for 0.5 h to obtain a mixture C; wherein a molar ratio of cobalt, copper, zinc, manganese to nickel in the metal salt precursor is 1:1:3:3:5, and a concentration of each metal ion in the metal salt precursor is independently 0.2 mol / L, a volume of the metal salt precursor is 4500 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and a stirring speed is independently 400 r / min;

[0081] (4) hydrothermal reaction of the mixture C at 150 ℃ and 5 MPa for 85 h to obtain a solid-phase product through solid-liquid separation;

[0082] (5) sequentially washing the solid-phase product, drying the solid-phase product at 80 ℃ for 12 h, calcining the solid-phase product at 500 ℃ for 10 h, and hydrogen reduction of the solid-phase product at 600 ℃ for 2 h at a hydrogen flow rate of 7 mL / min to obtain the titanium silicalite encapsulated nickel-based nanometer alloy catalyst.

[0083] Embodiment 3

[0084] The embodiment provides a titanium silicalite encapsulated nickel-based nanometer alloy catalyst, which comprises a carrier and a nanometer alloy encapsulated in the carrier, and the carrier comprises titanium silicalite.

[0085] The metal in the nanometer alloy comprises nickel and a second metal, the second metal is a combination of cobalt, copper, zinc and manganese, a molar ratio of cobalt, copper, zinc, manganese to nickel is 4:4:3:3:10, the nanometer alloy exists in the form of alloy particles, a D50 particle size of the alloy particles is 4.5 nm, and a mass percentage of nickel, cobalt, copper, zinc and manganese in the catalyst is respectively 0.88 wt%, 0.35 wt%, 0.35 wt%, 0.26 wt% and 0.26 wt%.

[0086] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, and the preparation method comprises the following steps:

[0087] (1) a mixture solution of 15 g of tetrapropylammonium hydroxide and 27 g of water is first mixed with 10 g of tetraethyl silicate for 7 h to obtain a mixture A;

[0088] (2) a mixture solution of 0.3 g of tetrabutyl titanate and 3 mL of isopropyl alcohol is second mixed with the mixture A for 3.5 h to obtain a mixture B;

[0089] (3) nitrate salts of nickel, cobalt, copper, zinc and manganese are dissolved in ethylenediamine to obtain a metal salt precursor, and the metal salt precursor is third mixed with the mixture B for 0.7 h to obtain a mixture C; wherein, a molar ratio of cobalt, copper, zinc, manganese to nickel in the metal salt precursor is 4:4:3:3:10, a concentration of each metal ion in the metal salt precursor is independently 1 mol / L, a volume of the metal salt precursor is 900 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and a rotating speed of stirring is independently 500 r / min;

[0090] (4) the mixture C is subjected to a hydrothermal reaction at 160 ℃ and 1 MPa for 72 h, and a solid-phase product is obtained through solid-liquid separation;

[0091] (5) the solid-phase product is sequentially subjected to washing, drying treatment at 70 ℃ for 18 h, calcination treatment at 600 ℃ for 9 h and hydrogen reduction treatment at 650 ℃ for 1.5 h, and a flow rate of hydrogen is 5 mL / min, so as to prepare the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst.

[0092] Embodiment 4

[0093] The embodiment provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which comprises a carrier and a nanoscale alloy encapsulated in the carrier, and the carrier comprises titanium silicalite.

[0094] The metal in the nanoscale alloy comprises nickel and a second metal, the second metal is a combination of cobalt, copper and zinc, a molar ratio of cobalt, copper, zinc to nickel is 3:3:2:6, the nanoscale alloy exists in the form of alloy particles, a D50 particle size of the alloy particles is 3.5 nm, and mass percentage contents of nickel, cobalt, copper and zinc in the catalyst are 0.84 wt%, 0.42 wt%, 0.42 wt% and 0.28 wt%.

[0095] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, and the preparation method comprises the following steps:

[0096] (1) a mixed solution of 13 g of tetrapropylammonium hydroxide and 25.2 g of water is first mixed with 8.32 g of tetraethyl silicate for 6 h to obtain a mixture A;

[0097] (2) a mixed solution of 0.272 g of tetrabutyl titanate and 2 mL of isopropyl alcohol is second mixed with the mixture A for 3 h to obtain a mixture B;

[0098] (3) nitrate salts of nickel, cobalt, copper and zinc are dissolved in ethylenediamine to obtain a metal salt precursor, and the metal salt precursor is third mixed with the mixture B for 1 h to obtain a mixture C; wherein the molar ratio of cobalt, copper, zinc to nickel in the metal salt precursor is 3:3:2:6, the concentration of each metal ion in the metal salt precursor is independently 0.5 mol / L, the volume of the metal salt precursor is 1680 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and the stirring speed is independently 200 r / min;

[0099] (4) the mixture C is subjected to hydrothermal reaction at 170 ℃ and 3 MPa for 96 h, and a solid-phase product is obtained through solid-liquid separation;

[0100] (5) the solid-phase product is sequentially subjected to washing, drying treatment at 60 ℃ for 24 h, calcination treatment at 550 ℃ for 8 h and hydrogen reduction treatment at 700 ℃ for 1 h, and the flow rate of hydrogen is 10 mL / min, so as to prepare the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst.

[0101] Embodiment 5

[0102] The embodiment provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which comprises a carrier and a nanoscale alloy encapsulated in the carrier, and the carrier comprises titanium silicalite.

[0103] The metal in the nanoscale alloy comprises nickel and a second metal, the second metal is a combination of cobalt, copper and manganese, the molar ratio of cobalt, copper, manganese to nickel is 3:3:1:6, the nanoscale alloy exists in the form of alloy particles, the D50 particle size of the alloy particles is 4.5 nm, and the mass percentage of the four metals of nickel, cobalt, copper and manganese in the catalyst is 0.84 wt%, 0.42 wt%, 0.42 wt% and 0.14 wt%.

[0104] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, and the preparation method comprises the following steps:

[0105] (1) a mixed solution of 15 g of tetrapropylammonium hydroxide and 27 g of water is first mixed with 10 g of tetraethyl silicate for 7 h to obtain a mixture A;

[0106] (2) a mixed solution of 0.3 g of tetrabutyl titanate and 3 mL of isopropyl alcohol is second mixed with the mixture A for 3.5 h to obtain a mixture B;

[0107] (3) nitrates of nickel, cobalt, copper and manganese are dissolved in ethylenediamine to obtain a metal salt precursor, and the metal salt precursor is third mixed with the mixture B for 0.7 h to obtain a mixture C; wherein the molar ratio of cobalt, copper, manganese to nickel in the metal salt precursor is 3:3:1:6, the concentration of each metal ion in the metal salt precursor is independently 0.5 mol / L, the volume of the metal salt precursor is 1560 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and the stirring speed is independently 500 r / min;

[0108] (4) the mixture C is subjected to hydrothermal reaction at 160 ℃ and 1 MPa for 72 h, and a solid-phase product is obtained through solid-liquid separation;

[0109] (5) the solid-phase product is sequentially subjected to washing, drying treatment at 70 ℃ for 18 h, calcination treatment at 600 ℃ for 9 h and hydrogen reduction treatment at 650 ℃ for 1 h, and the flow rate of hydrogen is 10 mL / min, so as to prepare the titanium silicalite encapsulated nickel-based nanoscale alloy catalyst.

[0110] Embodiment 6

[0111] The embodiment provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which comprises a carrier and a nanoscale alloy encapsulated in the carrier, and the carrier comprises titanium silicalite;

[0112] The metal in the nanoscale alloy comprises nickel and a second metal, the second metal is a combination of cobalt, zinc and manganese, the molar ratio of cobalt, zinc, manganese to nickel is 3:2:1:6, the nanoscale alloy exists in the form of alloy particles, the D50 particle size of the alloy particles is 4.0 nm, and the mass percentage of the four metals of nickel, cobalt, zinc and manganese in the catalyst is 0.84 wt%, 0.42 wt%, 0.28 wt% and 0.14 wt%.

[0113] The embodiment also provides a preparation method of the titanium silicalite encapsulated nickel-based nanometer alloy catalyst, and the preparation method comprises the following steps:

[0114] (1) a first mixing of a mixed solution of 10 g of tetrapropylammonium hydroxide and 26 g of water with 9.1 g of tetraethyl silicate for 6.5 h to obtain a mixture A;

[0115] (2) a second mixing of a mixed solution of 0.21 g of tetrabutyl titanate and 2.5 mL of isopropyl alcohol with the mixture A for 3.5 h to obtain a mixture B;

[0116] (3) dissolving nitrate salts of nickel, cobalt, zinc and manganese in ethylenediamine to obtain a metal salt precursor, and third mixing of the metal salt precursor with the mixture B for 0.5 h to obtain a mixture C; wherein the molar ratio of cobalt, zinc, manganese to nickel in the metal salt precursor is 3:2:1:6, the concentration of each metal ion in the metal salt precursor is independently 0.5 mol / L, the volume of the metal salt precursor is 1440 μL, and the first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring, and the stirring speed is independently 400 r / min;

[0117] (4) hydrothermal reaction of the mixture C at 150 ℃ and 5 MPa for 85 h to obtain a solid-phase product through solid-liquid separation;

[0118] (5) sequentially washing the solid-phase product, drying at 80 ℃ for 12 h, calcining at 500 ℃ for 10 h, and hydrogen reduction at 600 ℃ for 1 h at a hydrogen flow rate of 10 mL / min to obtain the titanium silicalite encapsulated nickel-based nanometer alloy catalyst.

[0119] Embodiment 7

[0120] The embodiment provides a titanium silicalite encapsulated nickel-based nanometer alloy catalyst, which is different from the embodiment 1 only in that, except that the temperature of the hydrothermal treatment in step (4) in the preparation method is 130 ℃, the rest is the same as the embodiment 1.

[0121] Embodiment 8

[0122] The embodiment provides a titanium silicalite encapsulated nickel-based nanometer alloy catalyst, which is different from the embodiment 1 only in that, except that the temperature of the hydrothermal treatment in step (4) in the preparation method is 190 ℃, the rest is the same as the embodiment 1.

[0123] Embodiment 9

[0124] The present example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that the time of hydrothermal treatment in step (4) of the preparation method is 60 h.

[0125] Example 10

[0126] The present example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that the time of hydrothermal treatment in step (4) of the preparation method is 110 h.

[0127] Comparative Example 1

[0128] The present comparative example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that the second metal is cobalt and copper.

[0129] The preparation method refers to that of Example 1, which is identical except that the addition of the second metal in step (3) is different, and no zinc and manganese is added, and the reduced amount is proportionally distributed to other components of the metal salt precursor.

[0130] Comparative Example 2

[0131] The present comparative example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that the second metal is zinc and manganese.

[0132] The preparation method refers to that of Example 1, which is identical except that the addition of the second metal in step (3) is different, and no cobalt and copper is added, and the reduced amount is proportionally distributed to other components of the metal salt precursor.

[0133] Comparative Example 3

[0134] The present comparative example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that the second metal is manganese.

[0135] The preparation method refers to that of Example 1, which is identical except that the addition of the second metal in step (3) is different, and no cobalt, copper and zinc is added, and the reduced amount is proportionally distributed to other components of the metal salt precursor.

[0136] Comparative Example 4

[0137] The present comparative example provides a titanium silicalite encapsulated nickel-based nanoscale alloy catalyst, which is identical to that of Example 1 except that no second metal is added.

[0138] The preparation method refers to that of Example 1, which is identical except that no second metal is added in step (3), and the reduced amount is proportionally distributed to other components of the metal salt precursor.

[0139] The XRD spectra of the catalysts obtained in Comparative Example 4 and Example 1 and the titanium silicalite support are shown in FIG. 1, and Figure 1 Figure 1 As can be seen, the characteristic diffraction peaks of the catalysts are very close to those of the original titanium silicalite, indicating that the nickel and nanoparticles are uniformly distributed in the titanium silicalite. The SEM spectra of the catalysts obtained in Comparative Example 4 and Example 1 and the titanium silicalite support are shown in FIG. 2, and Figure 2 Figure 2 As can be seen, the SEM images of the obtained catalysts and the original titanium silicalite are both hexagonal prism-shaped, indicating that the incorporation of nickel and nanoparticles does not change the morphology and structure of the support titanium silicalite. The preparation method of the titanium silicalite support is as described in Example 1, except that step (3) is omitted.

[0140] Comparative Example 5

[0141] This comparative example provides a nickel-based nanometer alloy catalyst, which is different from Example 1 only in that the support is an α-Al2O3molecular sieve.

[0142] The preparation method comprises: taking an α-Al2O3molecular sieve, and performing encapsulation according to steps (3-5) in Example 1 to obtain an α-Al2O3molecular sieve-encapsulated nickel-based nanometer alloy catalyst.

[0143] Comparative Example 6

[0144] This comparative example provides a titanium silicalite-encapsulated nickel-based nanometer alloy catalyst, which is different from Example 1 only in that step (5) in the preparation method does not include a reduction treatment, and the rest is the same as Example 1.

[0145] Performance test:

[0146] The catalysts obtained in Examples 1-10 and Comparative Examples 1-6 above were used in a methane dry reforming reaction, and the catalyst activity was tested by a fixed bed tubular reactor. The temperature was adjusted by a fixed bed control heating furnace, and the gas flow was controlled by a mass flow meter connected to the fixed bed. The reaction system was at atmospheric pressure. Before the test, 100 mg of catalyst and 200 mg of quartz sand were mixed uniformly and loaded into a quartz tube with a light receiving area of 1 cm 2 . Appropriate amounts of quartz wool were inserted into both ends. During the reaction, the reaction gas (40% CH4, 40% CO2, Ar balance) passed through the reaction tube, and the catalyst surface was irradiated by a 300 W (PLS-SXE300+, Beijing Perfectlight) xenon lamp. The light intensity on the catalyst was adjusted by adjusting the current value of the xenon lamp, and the light intensity was calibrated using a light power meter (Perfectlight, PL-MW2000). The product gas was analyzed by a gas chromatograph with a thermal conductivity detector (TCD).​​

[0147] The reforming process is as follows: hydrogen in the system is replaced by Ar purging, and after purging is completed, pure argon is switched to reaction gas (40% CH4, 40% CO2, Ar balance), the gas flow is 5 mL / min, the space velocity is 3000 mL / g / h, and a xenon lamp is used for light irradiation at the same time, the light intensity is 1.83 W / cm 2 After 10 minutes of switching to the reaction gas, on-line analysis is started at 450℃, and the catalytic data of the catalyst at 450℃ is tested.

[0148] The test results are shown in Table 1.

[0149] Table 1

[0150]

[0151] It can be seen from the test results that:

[0152] (1) It can be seen from Examples 1 to 6 that the titanium silicalite encapsulated nickel-based nanometer alloy catalyst provided by the application uses titanium silicalite as a carrier, improves the photo-thermal conversion efficiency by providing thermal insulation and infrared shielding, and limits the position of the nickel-based nanometer alloy in space, the nickel-based nanometer alloy promotes the adsorption and activation of intermediate substances, and the metal nickel is used as the main active component to realize high yield and long-term stability in cooperation with the second metal.

[0153] (2) It can be seen from Examples 1 and 7-8 that compared with Example 1, the catalytic efficiency of the catalyst prepared in Examples 7-8 is slightly reduced, and the reason is that too high hydrothermal temperature can cause partial desilication and even collapse of the molecular sieve framework, destroy the regular microporous structure, and the specific surface area decreases significantly, the crystal grows too fast and too violent, which can cause the nickel-based high-entropy alloy nanoparticles inside to be "extruded" or exposed on the outer surface of the molecular sieve, losing the limitation and protection of encapsulation, the temperature is too low, the driving force of the hydrothermal reaction is not enough, and the titanium silicalite framework cannot form a complete and highly crystalline framework, and titanium cannot be effectively doped into the molecular sieve framework, so the hydrothermal temperature needs to be limited within a certain range.

[0154] (3) It can be seen from Examples 1 and 9-10 that compared with Example 1, the catalytic efficiency of the catalyst prepared in Examples 9-10 is slightly reduced, and the reason is that too long hydrothermal time will cause "over-crystallization", which can cause partial desilication and even collapse of the molecular sieve framework, destroy the regular microporous structure, and the specific surface area decreases significantly, the crystal grows too fast and too violent, which can cause the nickel-based high-entropy alloy nanoparticles inside to be "extruded" or exposed on the outer surface of the molecular sieve, losing the limitation and protection of encapsulation, the temperature is too low, the driving force of the hydrothermal reaction is not enough, and the titanium silicalite framework cannot form a complete and highly crystalline framework, and titanium cannot be effectively doped into the molecular sieve framework, so the hydrothermal temperature needs to be limited within a certain range.

[0155] (4) It can be seen from Example 1 and Comparative Examples 1-3 that when the second metal is only added with cobalt and copper, zinc and manganese or only added with manganese, the yield of CO is significantly reduced, and thus it can be seen that the present application can significantly improve the yield of CO by limiting the second metal to include a combination of at least three of cobalt, copper, zinc or manganese, and especially when the second metal is cobalt, copper, zinc and manganese, the catalyst has higher activity and anti-coking stability.

[0156] (5) It can be seen from Example 1 and Comparative Example 4 that when the second metal is not added, the yield of CO of the titanium silicalite encapsulated nickel nano-alloy catalyst prepared is significantly reduced, and thus it can be seen that the present application significantly improves the activity and anti-coking stability of the catalyst through the synergistic effect of nickel and the second metal, and the efficiency of the methane dry reforming is higher.

[0157] (6) It can be seen from Example 1 and Comparative Example 5 that when α-Al2O3 molecular sieve is selected for encapsulation, the yield of CO is significantly reduced, and the efficiency of the methane dry reforming is obviously reduced, and thus it can be seen that the present application realizes unpredictable technical effects through the selection of the molecular sieve for encapsulation. The unique pore structure, hydrophobicity and specific function of titanium species of the titanium silicalite molecular sieve, together with the synergistic effect of the nickel-based nano-alloy, jointly solve the core challenges in the methane dry reforming reaction, solve the problems of carbon deposition and sintering, inhibit cracking and coking through the weakly acidic framework, realize in-situ carbon removal through the redox capacity of the titanium species, limit the formation of macromolecular carbon deposition through the pore size, stabilize the nano-alloy particles through the physical encapsulation effect of the rigid pore, and through the combined action of these factors, the activity, anti-coking capacity and thermal stability of the catalyst are significantly improved.

[0158] (7) It can be seen from Example 1 and Comparative Example 6 that when the catalyst is not subjected to reduction treatment in the preparation method, the efficiency of the methane dry reforming is obviously low. The reason is that when the reduction treatment is not performed, the active component exists in the form of metal oxide, lacks metal active sites: cannot effectively activate CH4 and CO2, and the reaction cannot be started; the carbon removal mechanism is invalid: cannot effectively activate CO2 to provide surface oxygen for removing carbon deposition, resulting in rapid coverage of the catalyst by carbon deposition and deactivation; the alloy structure is missing: cannot form an alloy active center with a synergistic catalytic effect, and thus it can be seen that the reduction treatment is an indispensable step for converting the nano-alloy catalyst into a high-activity catalyst, and forms the metal active sites.

[0159] In summary, the catalyst described in the application takes titanium-silicon molecular sieve as a carrier, nanoparticles are encapsulated in the titanium-silicon molecular sieve, the metal in the nano-alloy includes nickel and a second metal, the second metal includes any one or a combination of at least two of cobalt, copper, zinc or manganese, the titanium-silicon molecular sieve shell improves the light-heat conversion efficiency by providing thermal insulation and infrared shielding, and spatially limits the position of the nickel-based nano-alloy, the nanoparticles with high-entropy effect can promote the adsorption and activation of intermediate substances, the prepared titanium-silicon molecular sieve encapsulated nickel-based nano-alloy catalyst has high activity and outstanding anti-coking capacity and thermal stability at the same time, and can efficiently catalyze the methane dry reforming reaction at low temperature.

[0160] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the application fall within the protection scope and disclosure scope of the application.

Claims

1. A titanium silicalite encapsulated nickel-based nanolayered alloy catalyst characterized by, The catalyst includes a support and a nano-alloy encapsulated within the support; The carrier includes a titanium-silicon molecular sieve; The metal in the nanoalloy includes nickel and a second metal, wherein the second metal includes a combination of at least three of cobalt, copper, zinc, or manganese.

2. The catalyst according to claim 1, characterized in that, The nano-alloy exists in the form of alloy particles; Preferably, the particle size of the alloy particles is 2-7.5 nm; Preferably, the mass percentage of each metal in the catalyst is independently 0.1-5 wt%; Preferably, the molar ratio of any one of the second metals to nickel is independently (1-4):(5-10).

3. A method for preparing a nickel-based nanoalloy catalyst encapsulated in titanium-silicon molecular sieves according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) The mixed solution of organic template agent and water is first mixed with silicon source to obtain mixture A; (2) The mixture of titanium source and organic solvent is mixed with the mixture A in a second mixing process to obtain mixture B; (3) Dissolve the nickel salt and the second metal salt in an organic amine complexing agent to obtain a metal salt precursor, and then mix the metal salt precursor with the mixture B in a third mixing process to obtain mixture C; (4) The mixture C is subjected to a hydrothermal reaction, and a solid product is obtained by solid-liquid separation; (5) The solid product is washed, dried, calcined and reduced in sequence to prepare the nickel-based nano-alloy catalyst encapsulated by the titanium-silicon molecular sieve.

4. The preparation method according to claim 3, characterized in that, The organic template agent in step (1) includes tetrapropylammonium hydroxide or tetraethylammonium hydroxide, preferably tetrapropylammonium hydroxide; Preferably, the silicon source in step (1) includes any one of tetraethyl silicate, silica sol or water glass, preferably tetraethyl silicate; Preferably, the titanium source in step (2) includes any one of tetrabutyl titanate, tetraethyl titanate or tetraisopropyl titanate, preferably tetrabutyl titanate; Preferably, the organic solvent in step (2) includes isopropanol; Preferably, the organic amine complexing agent in step (3) includes any one of ethylenediamine, ethylenediaminetetraacetic acid, or diethylamine, preferably ethylenediamine; Preferably, in step (3), the second metal salt includes any one of the nitrates, chlorides, or sulfates of cobalt, copper, zinc, or manganese, and in step (3), the nickel salt includes any one of the nitrates, chlorides, or sulfates of nickel.

5. The preparation method according to claim 3 or 4, characterized in that, The mass ratio of the organic template agent, water and silicon source in step (1) is (10-15):(25-27):(8-10); Preferably, the volume ratio of the titanium source and the organic solvent in step (2) is (0.2-0.3):(2-3); Preferably, in step (3), the molar ratio of any metal element in the second metal salt to the nickel element in the nickel salt is independently (1-4):(5-10); Preferably, the concentration of each metal ion in the metal salt precursor in step (3) is independently 0.2-1 mol / L.

6. The preparation method according to any one of claims 3-5, characterized in that, Step (1) the first mixing, step (2) the second mixing and step (3) the third mixing are all carried out under stirring conditions, and the stirring speed is 200-500 r / min for each independently; Preferably, the mixing time in step (1) is 6-7 hours; Preferably, the mixing time in step (2) is 3-4 hours; Preferably, the time for the third mixing in step (3) is 0.5-1h.

7. The preparation method according to any one of claims 3-6, characterized in that, The temperature of the hydrothermal reaction in step (4) is 150-170℃; Preferably, the pressure of the hydrothermal reaction in step (4) is 1-5 MPa; Preferably, the hydrothermal reaction time in step (4) is 72-96 hours.

8. The preparation method according to any one of claims 3-7, characterized in that, The drying temperature in step (5) is 60-80℃; Preferably, the drying process in step (5) takes 12-24 hours; Preferably, the calcination temperature in step (5) is 500-600℃; Preferably, the calcination treatment in step (5) takes 8-10 hours; Preferably, the temperature of the reduction treatment in step (5) is 600-700℃; Preferably, the reduction process in step (5) takes 1-2 hours; Preferably, the atmosphere for the reduction treatment in step (5) includes hydrogen; Preferably, the flow rate of the hydrogen gas is 5-10 mL / min.

9. The preparation method according to any one of claims 3-8, characterized in that, The preparation method includes the following steps: (1) Mix the organic template agent and water solution with the silicon source for 6-7 hours to obtain mixture A; wherein the organic template agent includes tetrapropylammonium hydroxide or tetraethylammonium hydroxide, and the silicon source includes any one of tetraethyl silicate, silica sol or water glass, and the mass ratio of the organic template agent, water and silicon source is (10-15):(25-27):(8-10); (2) Mix the mixture of titanium source and organic solvent with the mixture A for a second time for 3-4 hours to obtain mixture B; wherein the titanium source includes any one of tetrabutyl titanate, tetraethyl titanate or tetraisopropyl titanate, the organic solvent includes isopropanol, and the volume ratio of the titanium source to the organic solvent is (0.2-0.3):(2-3); (3) Dissolve the nickel salt and the second metal salt in an organic amine complexing agent to obtain a metal salt precursor. Mix the metal salt precursor with the mixture B for 0.5-1h to obtain a mixture C. The organic amine complexing agent includes any one of ethylenediamine, ethylenediaminetetraacetic acid or diethylamine. The second metal salt includes any one of nitrates, chlorides or sulfates of cobalt, copper, zinc or manganese. The nickel salt includes any one of nitrates, chlorides or sulfates of nickel. The molar ratio of any metal element in the second metal salt to the nickel element in the nickel salt is independently (1-4):(5-10). The concentration of each metal ion in the metal salt precursor is independently 0.2-1mol / L. The first mixing in step (1), the second mixing in step (2) and the third mixing in step (3) are all carried out under stirring conditions. The stirring speed is independently 200-500r / min. (4) The mixture C is subjected to hydrothermal reaction at 150-170℃ and 1-5MPa for 72-96h, and the solid product is obtained by solid-liquid separation; (5) The solid product is washed, dried at 60-80℃ for 12-24h, calcined at 500-600℃ for 8-10h, and reduced at 600-700℃ for 1-2h. The atmosphere of the reduction treatment includes hydrogen, and the flow rate of hydrogen is 5-10mL / min. The nickel-based nano-alloy catalyst encapsulated by the titanium-silicon molecular sieve is prepared.

10. The use of a nickel-based nanoalloy catalyst encapsulated in titanium-silicon molecular sieves according to claim 1 or 2, characterized in that, The catalyst is used in the dry reforming reaction of methane; Preferably, the conditions of the methane dry reforming reaction include: the reaction space velocity is 3000-5000 mL / (h.g), the reaction temperature is 200-450℃, the reaction light intensity is 1.5-2 W / cm 2 .

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