A shell-core structured catalyst for methane-carbon dioxide reforming to syngas, its preparation method and application

Abstract

This invention discloses a core-shell structured catalyst for methane-carbon dioxide reforming to syngas, its preparation method, and its application, belonging to the field of catalyst technology. The method involves loading a metal onto a nano-sized silica surface using atomic layer deposition or impregnation, followed by preparing a core-shell structured carbonaceous catalyst using a Pickering emulsion template method. The final catalyst is obtained through a simple process of filtration, washing, drying, etching, and calcination. The resulting catalyst consists of nickel, a promoter metal, and carbon. This invention utilizes readily available and low-cost raw materials such as nickel and carbon. The method is simple, requires minimal equipment, and has low production costs. The prepared product exhibits high catalytic activity, high conversion rates of methane and carbon dioxide, and good resistance to coking and stability. This invention can be widely used as a catalyst for methane-carbon dioxide reforming to syngas.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically the field of catalyst preparation technology for methane-carbon dioxide reforming to syngas, and more specifically relates to a shell-core structure catalyst for methane-carbon dioxide reforming to syngas, its preparation method and application. Background Technology

[0002] CO2 is widely considered the main culprit of global warming. Realizing the conversion and utilization of CO2, transforming it into a sustainable C1 resource, is of profound significance for improving global climate issues. Currently, one chemical conversion pathway for CO2 is the catalytic reforming of CO2 with CH4 to produce syngas. This reaction can simultaneously convert both CH4 and CO2, two greenhouse gases, and the reaction system produces syngas with an H2 / CO ≈ 1 ratio, which can then be directly used as raw materials for carbonyl synthesis and Fischer-Tropsch synthesis.

[0003] CH4-CO2 reforming catalysts are mainly supported catalysts, with those using non-precious metal Ni as the active component being the most commonly used. However, Ni-based catalysts are prone to deactivation during prolonged high-temperature reactions, mainly due to two reasons: (1) carbon deposits on the catalyst surface, with carbon species that are difficult to eliminate through oxidation clogging the catalyst pores, leading to a decrease in catalyst activity or even deactivation; (2) sintering of the Ni active component at high temperatures, resulting in a significant decrease in the specific surface area and number of active sites, thus causing deactivation. Encapsulating Ni nanoparticles within a support has been widely considered a strategy for preparing methane dry reforming catalysts with excellent anti-sintering and anti-carbon deposition properties. However, these core-shell catalyst supports are mainly oxides, such as alumina, silica, zirconium oxide, and molecular sieves. Compared to oxide supports, carbonaceous supports have many advantages. For example, carbon materials have well-developed pore structures, excellent mechanical strength, high thermal stability, and resistance to acid and alkali corrosion. More importantly, carbonaceous supports are not susceptible to sulfur poisoning and have good adaptability to feedstock gases. They can be applied to reforming systems such as shale gas, associated gas from oil fields, coke oven gas, and gasified coal gas without requiring pre-desulfurization treatment of these gases. However, current core-shell structured carbon nanomaterial composite catalysts suffer from complex catalyst forming technology, making it difficult to meet the requirements for catalyst particle size and strength in fixed-bed or fluidized-bed reactors at higher reaction temperatures.

[0004] CN103816913A discloses a catalyst using activated carbon as a support and cobalt, zirconium, and molybdenum polymetallic substances as active components, with activated carbon accounting for 80-89% and cobalt, zirconium, and molybdenum polymetallic active substances accounting for 11-20%. This invention first uses corn cobs and lignite as raw materials to prepare mixed activated carbon through potassium carbonate activation, and then uses an ultrasonic impregnation method to load the polymetallic active components, which has the advantages of uniform distribution of active components and resistance to carbon deposition. However, due to the weak interaction between the active components and the activated carbon support, it is difficult to avoid the sintering of active metals under high-temperature conditions.

[0005] Chinese patent application CN103566936A discloses a "method for producing syngas from methane via carbon dioxide reforming." This catalyst also belongs to the category of carbon-based supported metal catalysts. The catalyst support is obtained from lignite through a series of treatments. Specifically, the lignite is carbonized at 600–800°C to obtain lignite semi-coke, which is then activated in supercritical water for 3–5 hours to obtain lignite activated carbon. The lignite activated carbon is mixed with ammonia water, soaked in a sealed container, and placed in a sealed, pressure-controlled, temperature-controlled reactor for a hydrothermal reaction at a reaction temperature of 800–1200°C and a reaction pressure of 1–6 MPa. The catalyst is obtained by impregnating ammonia-modified lignite activated carbon with cobalt nitrate solution under high pressure (3–5 MPa), drying, and calcining. The preparation process of this catalyst is complex, especially the support modification, which requires high temperature and high pressure, making it very demanding and unsuitable for widespread application. Furthermore, this catalyst must be supported with metallic Co and reacted at 950°C to achieve good catalytic activity.

[0006] Chinese patent application CN104984769B discloses a "method for producing a carbon-based catalyst from methane and carbon dioxide reforming." This catalyst involves mixing and grinding coal direct liquefaction residue with a composite modifier at a mass ratio of 1:(1-3). The composite modifier comprises 90%-98% alkali and 2%-10% nitrate by mass fraction. The resulting homogeneous mixture is then carbonized under an inert atmosphere. The carbonized mixture is subsequently cooled and washed until neutral. The neutralized mixture is then dried to obtain the carbon-based catalyst. However, this carbon-based catalyst lacks metallic active components, resulting in low stability during continuous reactions and difficulties in catalyst forming.

[0007] Therefore, it can be seen that the catalysts prepared above are either difficult to form or require harsh reaction conditions, resulting in a lack of suitable catalysts for the methane-carbon dioxide reforming process. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a shell-core structure catalyst for the reforming of methane into syngas, its preparation method and application. It mainly utilizes the special confined space of the shell-core structure and improves the efficiency of the CH4-CO2 reforming reaction by controlling the structure and composition of the catalyst, thus solving the problems of easy sintering and carbon deposition of active components in nickel-based catalysts and the difficulty in forming carbon supports.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] A method for preparing a shell-core structured catalyst for methane-carbon dioxide reforming to syngas includes the following steps:

[0011] Step 1: Nickel and metal oxides are deposited onto the surface of hydrophilic silica nanospheres using atomic deposition or impregnation methods to obtain Ni-M x O y / SiO2 bimetallic composite material;

[0012] Step 2: Dissolve hydrophilic silica nanospheres in toluene, add triethylamine and methyltrimethoxysilane, reflux and centrifuge, dry the centrifuged product to obtain amphiphilic silica nanosphere particles;

[0013] Step 3, Ni-M x O y A SiO2 bimetallic composite material and a carbon source were dissolved in water to obtain an aqueous solution; amphiphilic silica nanospheres were dissolved in an oil emulsion to obtain an oil solution; the aqueous and oil solutions were mixed and stirred to obtain a Pickering solution with an oil phase encapsulating a water phase; the Pickering solution was subjected to a hydrothermal reaction to obtain a solution encapsulated with metallic Ni and M. x O y The polymer spheres; the polymer spheres have a multi-core shell structure, wherein a large sphere encapsulates multiple smaller spheres, and each smaller sphere encapsulates metallic Ni and M. x O y ;

[0014] Step 4, encapsulate the metals Ni and M x O y The polymer spheres were dried and then etched. The etched product was then calcined to obtain Ni-M. x O y @C catalyst; Ni-M x O y Both the large and small spheres in the @C catalyst are porous hollow carbon structures.

[0015] A further improvement of the present invention is that:

[0016] Preferably, in step 1, Ni-M is prepared by atomic deposition or impregnation.x O y In the process of creating the / SiO2 bimetallic composite material, Ni is prepared from nickel metal salt, and the metal oxide is prepared from the corresponding metal salt.

[0017] Preferably, the emulsion oil phase in step 3 is any one or a mixture of benzene, toluene, hexane or octane.

[0018] Preferably, the carbon source in step 3 is a biomass carbon source.

[0019] Preferably, in step 2, the mass ratio of hydrophilic silica nanospheres to toluene solution is 1:5; the molar ratio of hydrophilic silica nanospheres, triethylamine, and methyltrimethoxysilane is 5:1:1.

[0020] Preferably, in step 3, Ni-M x O y The mass ratio of the SiO2 bimetallic composite material, the oil phase, and the carbon source is 1:20:9.

[0021] A core-shell structure catalyst for methane-carbon dioxide reforming to syngas has a multi-core-shell structure, consisting of a large sphere encapsulating multiple smaller spheres, each encapsulating metallic Ni and M. x O y Both the large and small spheres are porous hollow carbon spheres.

[0022] Preferably, by mass percentage, the multi-core-shell structure contains 75–94 wt% carbon, 5–15 wt% metallic Ni, and M x O y The mass percentage is 1–10 wt%.

[0023] Preferably, the catalyst has a bonding index G RI Reaching 95, strength SI4 25 >95%, thermal stability TS +6 >95%.

[0024] Application of a shell-core structured catalyst for the reforming of methane and carbon dioxide to syngas, used for catalyzing the reforming of methane and carbon dioxide to syngas.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention discloses a method for preparing a core-shell structured catalyst for methane-carbon dioxide reforming to syngas, belonging to the technical field of catalyst preparation for methane-carbon dioxide reforming to syngas. The method involves loading a metal onto a nano-sized silica surface using atomic layer deposition or impregnation, followed by preparing a core-shell structured carbonaceous catalyst using a Pickering emulsion template method. The final catalyst is obtained through a simple process of filtration, washing, drying, etching, and calcination. The resulting catalyst consists of nickel, an auxiliary metal, and carbon. This invention utilizes readily available and low-cost raw materials such as nickel and carbon. The method is simple, requires minimal equipment, and has low production costs. The prepared product exhibits high catalytic activity, high conversion rates of methane and carbon dioxide, and good resistance to coking and stability. This invention can be widely used as a catalyst for methane-carbon dioxide reforming to syngas.

[0027] Highly dispersed hydrophilic metal / silica composite materials were prepared on the surface of a hydrophilic silica template rich in silanol groups using impregnation or atomic layer deposition methods. Micron-sized carbon sphere shells were constructed using the oil-water interface of a Pickering emulsion as a template. These composite materials were then used as a hard template to guide the assembly of internal nanoscale polymer sphere structures, resulting in a large sphere encapsulating a smaller sphere, with the smaller sphere containing Ni and M metals. x O y The structure consists of polymers for both the large and small spheres. After the hydrothermal reaction, micro / nano-sized hollow carbon spheres with encapsulated metal and a multi-hollow core structure (yolk-shell-shell) are prepared by etching and high-temperature calcination, which are the corresponding catalysts. During the calcination process, the catalyst can undergo simultaneous carbothermal reduction, and the polymer carbonizes to form carbon. The encapsulated active metal carbon shell-core structure composite metal catalyst obtained by this preparation method has high thermal stability, high anti-sintering performance, and exhibits high catalytic activity, selectivity and anti-carbon deposition ability in the methane-carbon dioxide reforming catalytic reaction.

[0028] This invention also discloses a core-shell structure catalyst for the reforming of methane and carbon dioxide to produce syngas. The catalyst has an overall core-shell structure, consisting of a large sphere encapsulating a smaller sphere, with the smaller sphere containing metallic Ni particles and M... x O yThe particles, both the large and small spheres, are porous carbon spheres. This structure encapsulates nickel within a core-shell structure, which acts as a confined space, inhibiting the sintering and coking of the active metal nanoparticles during high-temperature reactions in later catalytic applications. If carbon deposits occur on the nickel particle surface, oxygen provided by the metal oxide reacts with the carbon, generating gas that escapes through the pores of the shell, thus preventing carbon buildup on the nickel particle surface. In this invention, the large spheres are micrometer- or sub-millimeter-sized, and the small spheres are nanometer- or sub-micrometer-sized, allowing the catalyst to function at a specific size for subsequent applications.

[0029] Furthermore, the catalyst in this invention has an overall spherical structure. The spherical structure has a regular geometric structure and low flow resistance, which ensures the catalytic effect.

[0030] This invention also discloses the application of a shell-core structure catalyst for the reforming of methane into syngas, which has the following advantages in application:

[0031] 1. High conversion rates of methane and CO2. The catalyst prepared in this invention was subjected to online reaction monitoring using an online catalyst evaluation device at a CH4 / CO2 volume ratio of 1, a reaction temperature of 700℃, atmospheric pressure, and a gas space velocity of 2500 h⁻¹. -1 The conversion rate of methane is as high as 95%, and the conversion rate of carbon dioxide is also as high as 94%.

[0032] 2. Excellent resistance to coking and stability. The catalyst prepared in this invention did not show a significant decrease in catalytic activity after 120 hours of reaction.

[0033] 3. Raw materials are widely available and low in cost. This invention uses non-precious metal raw materials such as Ni and carbon, which are widely available and greatly reduce costs;

[0034] 4. The preparation process is simple and the production volume is large. The required catalyst carbon support can be rapidly prepared from silica using the Pickering emulsion method, which is a simple process;

[0035] 5. Simple equipment and low investment. The method of this invention only uses simple and commonly used instruments such as constant temperature water bath, drying oven, and tube furnace. If applied to industrial production, only simple constant temperature water bath and heating equipment are needed, resulting in low investment and easy promotion and utilization.

[0036] This invention can be widely used as a catalyst for the reforming of methane and carbon dioxide to produce syngas, and the preparation method used breaks the pattern of traditional preparation methods. Attached Figure Description

[0037] Figure 1This is a schematic flowchart illustrating the preparation method of the methane-carbon dioxide reforming encapsulated active metal carbonaceous shell-core composite metal catalyst provided in the embodiments of this application.

[0038] Figure 2 This is a schematic diagram of the structure of the methane-carbon dioxide reforming encapsulated active metal carbonaceous shell-core composite metal catalyst provided in the embodiments of this application.

[0039] Figure 3 This is a scanning electron microscope (SEM) image of the catalyst. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] This invention provides a methane-carbon dioxide reforming catalyst, which is made by supporting an active metal on a carbon material. The catalyst has a core-shell structure, with carbon spheres accounting for 75-94 wt% by mass, nickel active components accounting for 5-15 wt% by mass, and active auxiliary metal components accounting for 1-10 wt% by mass.

[0042] The methane-carbon dioxide reforming catalyst is a micro / nano-sized hollow carbon sphere with a porous, yolk-shell-shell structure encapsulated internally with metal. In other words, the catalyst is... Figure 2 The hollow carbon spheres shown are micro / nano-sized, with an internal structure of a large sphere enclosing a smaller sphere. Both the large and small spheres are porous hollow carbon spheres, and the smaller spheres contain composite nano-nickel particles and M. x O y Particles; M is magnesium, calcium, cerium or lanthanum.

[0043] The carbon microspheres are internal micron or nano-sized carbon spheres assembled using the Pickering emulsion method with hydrophilic silica composite material as a hard template.

[0044] Furthermore, the catalyst's binding index G RI Reaching 95, strength SI4 25 >95%, thermal stability TS +6 >95%.

[0045] like Figure 1 As shown, one embodiment of the present invention discloses a method for preparing a methane-carbon dioxide reforming catalyst, which includes the following steps:

[0046] S101 was prepared by loading Ni and auxiliary metal M onto the surface of hydrophilic silica nanospheres of different sizes via atomic layer deposition or impregnation methods to obtain Ni-M. x O y / SiO2 bimetallic composite material, wherein M x O y The catalyst is an oxide formed from the auxiliary metal. In the impregnation method, the nickel source and the auxiliary metal salt are co-dissolved in an aqueous solution, and silica is added. The two metals are then attached to the surface of commercial silica through equal-volume impregnation. In the atomic layer deposition method, the nickel-cadmium and auxiliary metal organic complex are deposited on the surface of silica, thus preparing Ni-M. x O y / SiO2 bimetallic composite material.

[0047] The ratio of nickel source to silicon dioxide ultimately results in a Ni loading in the catalyst between 5-15 wt%.

[0048] The nickel source used is a nickel metal salt, specifically any one or a mixture of nickel chloride, nickel acetylacetone, nickel oxalate, nickel dicerocene, nickel nitrate, or nickel acetate.

[0049] The mass ratio of nickel source to auxiliary metal salt is 15:1 to 1:2.

[0050] The auxiliary metal salt is any one or a mixture of magnesium nitrate, calcium nitrate, cerium nitrate, cerium chloride, or organometallic coordination compounds such as Ce(thd)4 and La(acac)3.

[0051] The silica material used is commercially available hydrophilic spherical silica with a size of 20–500 nm.

[0052] Preferred, Ni-M x O y / SiO2 bimetallic composite materials are prepared by atomic layer deposition. By controlling the process, the composite morphology and distance of the two metals on the silicon dioxide surface can be adjusted.

[0053] S102, select hydrophilic silica nanospheres of a specific size, dissolve the hydrophilic silica nanospheres in toluene solution, the mass ratio of hydrophilic silica nanospheres to toluene solution is 1:5; add appropriate amounts of triethylamine and methyltrimethoxysilane as crosslinking agents, reflux and centrifuge, dry to obtain amphiphilic silica nanosphere particles, that is, generate silica particles that are both hydrophilic and oleophilic.

[0054] In this process, after hydrophobic modification of the material surface, amphiphilic silica is dispersed in the oil phase of the emulsion. This step involves modifying the hydrophilic silica using a crosslinking agent to graft hydrophobic methyl groups onto the hydrophilic silica, making its water contact angle between 90-120°. The modified amphiphilic silica can serve as a solid active particle that stabilizes the oil-water interface and acts as an interfacial active particle to stabilize the Pickering emulsion in the next step.

[0055] Furthermore, the amounts of triethylamine and methyltrimethoxysilane are determined by the content of hydrophilic silica to be modified. For example, 5 mol of hydrophilic silica requires the addition of 1 mol of triethylamine and 1 mol of methyltrimethoxysilane, increasing proportionally.

[0056] S103, using the emulsion oil phase as the solvent, adds the amphiphilic silica nanospheres prepared in step S102; Ni-M dissolved in the emulsion oil phase is then added. x O y / An aqueous solution of SiO2 composite material and carbon source was used as the aqueous phase. The oil and aqueous phases were mixed and mechanically stirred to obtain a Pickerling emulsion (oil-in-water Pickerling solution) containing both an oil and a water phase. The Pickerling emulsion was placed in a tetrafluoroethylene-lined hydrothermal reactor and left at 100°C for 24 hours to obtain a solution encapsulated with metallic Ni and M. x O y Multi-core-shell structured micro / nano-sized polymer spheres, where micro / nano-size refers to micrometer or nanometer size. The product was finally collected after washing with water and ethanol. Ni-M x O y / SiO2 composite material: oil phase: carbon source = 1:20:9.

[0057] Furthermore, the Pickering emulsion consists of an aqueous phase and an oil phase. Here, the oil phase is the emulsion phase itself, and it only forms a Pickering emulsion after mixing with water. The modified amphiphilic silica, due to the grafting of hydrophobic methyl groups, is an amphiphilic silica material. This material possesses interfacial activity, allowing it to disperse at the oil-water interface of the Pickering emulsion and stabilizing this interface. The resulting Pickering emulsion exhibits good stability, with the oil-water interface serving as a template to construct a micron-sized carbon spherical shell layer. The composite hard template material (i.e., Ni-M) dispersed in the aqueous phase... x O y SiO2 can be used as a hard template for growing internal nanospheres into microspheres, guiding the assembly of the internal nanoscale carbon sphere shell, ultimately producing a regular core-shell structure, and preparing encapsulated metals (Ni and M). x O y And micro / nano-sized carbon spheres with a multi-core-shell structure.

[0058] Composite rigid template material (i.e., Ni-M) x O y Using SiO2 as a template for growing internal nanospheres, the carbon source first polymerizes and grows on the template surface. As polymerization proceeds, the thickness of the carbon sphere shell on the template surface gradually increases. By controlling the process, core-shell structures with different shell thicknesses can be obtained.

[0059] The oil-water interface of Pickering emulsion can serve as a template for growing microsphere shells. Water-soluble carbon sources polymerize in water and continuously migrate to the oil-water interface, where they further polymerize to obtain the shells of microspheres.

[0060] Furthermore, the carbon source is a mixture of one or more biomass carbon sources such as glucose, fructose, maltose, and sucrose, and melamine and urea.

[0061] Furthermore, the Pickering emulsion is stable, and the emulsion exists in a water-in-oil spherical form, Ni-M x O y / Both the SiO2 composite material and the carbon source undergo polymerization in water. Because the Pickering emulsion oil-water interface is stable, the oil and water phases cannot flow, forming a stable, confined aqueous spherical space. Therefore, the aqueous material can construct a carbon spherical shell after growth at the oil-water interface. During this process, the carbon source polymerizes in the aqueous phase, and Ni-M... x O y The SiO2 composite material is encapsulated inside.

[0062] Furthermore, the 10wt% Ni-supported catalyst was prepared as follows: 1 mol carbon source + 0.6 g Ni-M x O y / SiO2 composite material

[0063] This step creates a core-shell structure where a large sphere encloses a smaller sphere, with the smaller sphere containing nickel particles and metal oxides. The shell of this core-shell structure is a polymer, the composition of which is determined by the carbon source. For example, if the carbon source is glucose, the polymer is a glucose-based polymer; if the carbon source is fructose, the polymer is a fructose-based polymer.

[0064] S104, for the above-mentioned packaged metals Ni and M x O y Furthermore, micro / nano-sized polymer spheres with a multi-core-shell structure undergo drying, calcination, and carbonization treatment. The specific steps are as follows: the encapsulated metal polymer spheres prepared by S103 are dried at 100°C for 12-24 hours; the dried product is etched with sodium hydroxide and then dried again; the dried product is placed in a tube furnace for calcination and carbonization treatment, during which an inert gas is introduced; and after calcination and carbonization treatment at a suitable temperature, the nickel-based catalyst Ni-M of this invention is prepared.x O y @C catalyst.

[0065] Furthermore, drying at 100°C for 12-24 hours is used to dry the above-mentioned hydrothermal synthesis product, because the product is collected by washing with water and ethanol and needs to be dried to remove moisture.

[0066] Furthermore, nitrogen and argon gases are introduced during the calcination process, and the calcination temperature is between 500 and 900°C. The S103 product requires high-temperature carbonization treatment.

[0067] One embodiment of the present invention discloses the application of a nickel-based catalyst for methane-carbon dioxide reforming in the preparation of syngas, using methane and carbon dioxide as raw materials to prepare syngas under the catalytic action of the nickel-based catalyst for methane-carbon dioxide reforming.

[0068] The reaction temperature of methane and carbon dioxide is set at 550℃ to 850℃, which is the temperature gradient for selection. The catalyst in this invention has a multi-core-shell structure. First, the hollow internal structure facilitates the diffusion and mass transfer of gaseous reactant molecules; second, the confined microstructure helps enrich the reactants, increasing the local reactant concentration; both of these factors improve the catalyst efficiency. Finally, the presence of metal oxide promoters around Ni effectively suppresses carbon deposition on the catalyst.

[0069] The following description, in conjunction with specific embodiments, provides further details.

[0070] Example 1

[0071] The components and their mass percentages of a catalyst for the reforming of methane with carbon dioxide to produce syngas are as follows:

[0072] Nickel (Ni) 9.8%

[0073] Cerium oxide (CeO2) 5.3%

[0074] Carbon (C) 84.9%

[0075] The specific steps of a method for preparing a catalyst for reforming methane and carbon dioxide to produce syngas are as follows: Step S101, select a 20nm commercially available hydrophilic spherical silica template, and use an impregnation method to load metallic Ni and CeO2 onto the silica surface to prepare a Ni-CeO2 / SiO2 bimetallic composite material; use an equal-volume impregnation method, using nickel nitrate as a nickel precursor and cerium nitrate as a cerium oxide precursor, prepare a 20mL aqueous solution of the above precursor salts (containing 8.6g of nickel nitrate and 2.8g of cerium nitrate), and then directly impregnate 10g of hydrophilic silica into the aqueous solution, dry at 120℃ for 12h, and calcine in air at 550℃ for 4h.

[0076] Step S102: Select 60nm commercially available hydrophilic spherical silica for surface hydrophobic modification. Disperse 3g of hydrophilic silica nanospheres in 16mL toluene solution by sonication for 20min. Add 0.9138g triethylamine and 1.2273g methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use this solution to stabilize Pickering emulsion.

[0077] In step S103, 0.4 g of hydrophilic silica composite material (Ni-CeO2 / SiO2) and 3.68 g of glucose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulated with metals (Ni and CeO2) and possessing a multi-core structure.

[0078] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-CeO2@C catalyst of this invention is prepared.

[0079] Figure 3 The image shows the SEM characterization of the catalyst in Example 1, which has a Ni content of 9.8 wt%, a CeO content of 5.3 wt%, and a carbon content of 84.9 wt%. This catalyst consists of micron-sized shell-core structured carbon microspheres, with the shell containing Ni-M... x O y It is made of stacked hollow spheres with a composite core.

[0080] Example 2:

[0081] The components and their mass percentages of a catalyst for the reforming of methane with carbon dioxide to produce syngas are as follows:

[0082] Nickel (Ni) 8%

[0083] Cerium oxide (CeO2) 3%

[0084] Carbon (C) 89%

[0085] The specific steps of a method for preparing a catalyst for the reforming of methane and carbon dioxide to syngas are as follows:

[0086] Step S101: Select a 40nm commercially available hydrophilic spherical silica template, and use an impregnation method to load metallic Ni and CeO2 onto the silica surface to prepare a Ni-CeO2 / SiO2 bimetallic composite material; use an equal-volume impregnation method, with nickel nitrate as the nickel precursor and cerium chloride as the cerium oxide precursor, prepare a 20mL aqueous solution of the above precursor salts (containing 7g of nickel nitrate and 1.2g of cerium chloride), and then directly impregnate 10g of hydrophilic silica into the aqueous solution, dry at 120℃ for 12h, and calcine in air at 550℃ for 4h.

[0087] Step S102: Select 80nm commercial hydrophilic spherical silica for surface hydrophobic modification. Take 3g of hydrophilic silica nanospheres and disperse them in 16mL of toluene solution by sonication for 20min. Add 0.9138g of triethylamine and 1.2273g of methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use them as interfacial active particles to stabilize Pickering emulsion.

[0088] In step S103, 0.4 g of hydrophilic silica composite material (Ni-CeO2 / SiO2) and 4.6 g of glucose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and CeO2) with a multi-core structure.

[0089] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-CeO2@C catalyst of this invention is prepared.

[0090] Example 3:

[0091] The components and their mass percentages of a catalyst for the reforming of methane with carbon dioxide to produce syngas are as follows:

[0092] Nickel (Ni) 15%

[0093] Cerium oxide (CeO2) 10%

[0094] Carbon (C) 75%

[0095] The specific steps of a method for preparing a catalyst for the reforming of methane and carbon dioxide to syngas are as follows:

[0096] Step S101: Select an 80nm commercially available hydrophilic spherical silica template, and use an impregnation method to load metallic Ni and CeO2 onto the silica surface to prepare a Ni-CeO2 / SiO2 bimetallic composite material; use an equal-volume impregnation method, with nickel nitrate as the nickel precursor and cerium chloride as the cerium oxide precursor, prepare a 20mL aqueous solution of the above precursor salts (containing 13g of nickel nitrate and 4g of cerium nitrate), and then directly impregnate 10g of hydrophilic silica into the aqueous solution, dry at 120℃ for 12h, and calcine in air at 550℃ for 4h.

[0097] Step S102: Select 80nm commercial hydrophilic spherical silica for surface hydrophobic modification. Take 3g of hydrophilic silica nanospheres and disperse them in 16mL of toluene solution by sonication for 20min. Add 1.8138g of triethylamine and 1.9273g of methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use them as interfacial active particles to stabilize Pickering emulsion.

[0098] In step S103, 0.4 g of hydrophilic silica composite material (Ni-CeO2 / SiO2) and 7.6 g of glucose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and CeO2) with a multi-core structure.

[0099] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-CeO2@C catalyst of this invention is prepared.

[0100] Example 4:

[0101] The components and their mass percentages of a catalyst for the reforming of methane with carbon dioxide to produce syngas are as follows:

[0102] Nickel (Ni) 5%

[0103] Cerium oxide (CeO2) 1%

[0104] Carbon (C) 94%

[0105] The specific steps of a method for preparing a catalyst for the reforming of methane and carbon dioxide to syngas are as follows:

[0106] Step S101: Select a 200nm commercially available hydrophilic spherical silica template and load metallic Ni and CeO2 onto the silica surface using atomic layer deposition (ALD) to prepare a Ni-CeO2 / SiO2 bimetallic composite material. Use a commercially available thermal atomic layer deposition equipment, with nickel dicene as the nickel precursor and Ce(thd)4 as the cerium oxide precursor, at a deposition temperature of 200℃ to deposit Ni-CeO2. The ALD cycling method is used, with a nickel precursor pulse time of 40 cycles, a helium purging time of 120s, and finally, the auxiliary metal precursor is deposited on the carrier surface for 10 cycles.

[0107] Step S102: Select 100nm commercial hydrophilic spherical silica for surface hydrophobic modification. Take 3g of hydrophilic silica nanospheres and disperse them in 16mL of toluene solution by sonication for 20min. Add 0.7218g of triethylamine and 1.3728g of methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use them as interfacial active particles to stabilize Pickering emulsion.

[0108] In step S103, 0.4 g of hydrophilic silica composite material (Ni-CeO2 / SiO2) and 2.26 g of glucose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The mixture was then placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and CeO2) with a multi-core structure.

[0109] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-CeO2@C catalyst of this invention is prepared.

[0110] Example 5:

[0111] In this embodiment, the components and their mass percentages of the catalyst are as follows:

[0112] Nickel (Ni) 15

[0113] Magnesium oxide (MgO) 2.5

[0114] Carbon (C) 82.5

[0115] Step S101: Select a 20nm commercially available hydrophilic spherical silica template, and load metallic Ni and MgO onto the silica surface using an impregnation method to prepare a Ni-MgO / SiO2 bimetallic composite material; use an equal-volume impregnation method, with nickel oxalate as the nickel precursor and magnesium nitrate as the Mg precursor, prepare a 20mL aqueous solution of the above precursor salts (containing 10g of nickel oxalate and 2.47g of magnesium nitrate), and then directly impregnate 10g of hydrophilic silica into the aqueous solution, dry at 120℃ for 12h, and calcine in air at 550℃ for 4h.

[0116] Step S102: Select 60nm commercially available hydrophilic spherical silica for surface hydrophobic modification. Disperse 3g of hydrophilic silica nanospheres in 16mL toluene solution by sonication for 20min. Add 0.9138g triethylamine and 1.2273g methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use this solution to stabilize Pickering emulsion.

[0117] In step S103, 0.4 g of hydrophilic silica composite material (Ni-MgO / SiO2) and 2.4 g of fructose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and MgO) with a multi-core structure.

[0118] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-MgO@C catalyst of this invention is prepared.

[0119] Example 6:

[0120] In this embodiment, the components and their mass percentages of the catalyst are as follows:

[0121] Nickel (Ni) 10

[0122] Calcium oxide (CaO) 5

[0123] Carbon (C) 85

[0124] In step S101, a 20nm commercially available hydrophilic spherical silica template was selected, and metallic Ni and CaO were loaded onto the silica surface using an impregnation method to prepare a Ni-CaO / SiO2 bimetallic composite material. Using an equal-volume impregnation method, nickel oxalate was used as the nickel reaction precursor and calcium nitrate as the Ca precursor. The above precursor salts were prepared into a 20mL aqueous solution (containing 6.67g of nickel oxalate and 2.38g of calcium nitrate). Then, 10g of hydrophilic silica was directly impregnated into the aqueous solution, dried at 120℃ for 12h, and calcined in air at 550℃ for 4h.

[0125] Step S102: Select 60nm commercially available hydrophilic spherical silica for surface hydrophobic modification. Disperse 3g of hydrophilic silica nanospheres in 16mL toluene solution by sonication for 20min. Add 0.9138g triethylamine and 1.2273g methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use this solution to stabilize Pickering emulsion.

[0126] In step S103, 0.4 g of hydrophilic silica composite material (Ni-CaO / SiO2) and 2.32 g of sucrose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a high-pressure reactor lined with tetrafluoroethylene and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and CaO) with a multi-core structure.

[0127] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-CaO@C catalyst of this invention is prepared.

[0128] Example 7:

[0129] In this embodiment, the components and their mass percentages of the catalyst are as follows:

[0130] Nickel (Ni) 5

[0131] Lanthanum oxide (La₂O₃)₂

[0132] Carbon (C) 93

[0133] In step S101, a 20nm commercially available hydrophilic spherical silica template was selected, and metallic Ni and La2O3 were loaded onto the silica surface using atomic layer deposition (ALD) technology to prepare a Ni-La2O3 / SiO2 bimetallic composite material. A commercially available thermal atomic layer deposition equipment was used, with nickel dicene as the nickel precursor and La(acac)3 as the lanthanum oxide precursor. The deposition temperature was 200℃, and Ni-La2O3 was deposited using the ALD supercycle method. The nickel precursor pulse time was 40 cycles, the helium purging time was 120s, and finally the auxiliary metal precursor was deposited on the carrier surface for 15 cycles.

[0134] Step S102: Select 60nm commercially available hydrophilic spherical silica for surface hydrophobic modification. Disperse 3g of hydrophilic silica nanospheres in 16mL toluene solution by sonication for 20min. Add 0.9138g triethylamine and 1.2273g methyltrimethoxysilane as crosslinking agents. Reflux at 120℃ for 4h, centrifuge at 12000r / min for 5min, and dry at 110℃ for 12h. Use this solution to stabilize Pickering emulsion.

[0135] In step S103, 0.4 g of hydrophilic silica composite material (Ni-La2O3 / SiO2) and 3.24 g of fructose were dissolved in 5 mL of water and stirred at 60 °C until completely dissolved. 0.4 g of hydrophobic SiO2 nanospheres were ultrasonically dispersed in 10 mL of toluene solution for 20 min. The solutions were then mixed and placed in a homogenizer and stirred at 12000 r / min for 3 min to obtain a water-in-oil Pickering emulsion. The emulsion was placed in a tetrafluoroethylene-lined high-pressure reactor and placed at 100 °C for 24 h to obtain micron-sized polymer spheres encapsulating metals (Ni and MnO) with a multi-core structure.

[0136] In step S104, the encapsulated metal polymer spheres prepared in S103 are dried at 100°C for 24 hours. The dried product is then etched with 50 mL of 0.1 M sodium hydroxide for 3 hours and dried again. The dried product is placed in a tube furnace and carbonized under a nitrogen atmosphere of 0.1 MPa, starting from 20°C, the temperature is increased to 350°C at a rate of 2°C / min, maintained at 350°C for 2 hours, and then increased from 350°C to 600°C at a rate of 2°C / min, and maintained at 600°C for 3 hours. After carbonization, the nickel-based catalyst Ni-La2O3@C catalyst of this invention is prepared.

[0137] Table 1 Catalyst activity with different component contents

[0138]

[0139]

[0140] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a shell-core structured catalyst for methane-carbon dioxide reforming to syngas, characterized in that, Includes the following steps: Step 1: Nickel and metal oxides are deposited onto the surface of hydrophilic silica nanospheres using atomic deposition or impregnation methods to obtain Ni-M x O y / SiO2 bimetallic composite material; M x O y M in the figure is magnesium, calcium, cerium or lanthanum; the M x O y It can be CeO2, MgO, CaO or La2O3; Step 2: Dissolve hydrophilic silica nanospheres in toluene, add triethylamine and methyltrimethoxysilane, reflux and centrifuge, dry the centrifuged product to obtain amphiphilic silica nanosphere particles; Step 3, Ni-M x O y A SiO2 bimetallic composite material and a carbon source were dissolved in water to obtain an aqueous solution; amphiphilic silica nanospheres were dissolved in an oil emulsion to obtain an oil solution; the aqueous and oil solutions were mixed and stirred to obtain a Pickering solution with an oil phase encapsulating a water phase; the Pickering solution was subjected to a hydrothermal reaction to obtain a solution encapsulated with metallic Ni and M. x O y The polymer spheres; the polymer spheres have a multi-core shell structure, wherein a large sphere encapsulates multiple smaller spheres, and each smaller sphere encapsulates metallic Ni and M. x O y ; Step 4, encapsulate the metals Ni and M x O y The polymer spheres were dried and then etched. The etched product was then calcined to obtain Ni-M. x O y @C catalyst; Ni-M x O y Both the large and small spheres in the @C catalyst are porous hollow carbon structures.

2. The method for preparing a shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 1, characterized in that, In step 1, Ni-M is prepared by atomic deposition or impregnation. x O y In the process of creating the / SiO2 bimetallic composite material, Ni is prepared from nickel metal salt, and the metal oxide is prepared from the corresponding metal salt.

3. The method for preparing a shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 1, characterized in that, The emulsion oil phase in step 3 is any one or a mixture of benzene, toluene, hexane or octane.

4. The method for preparing a shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 1, characterized in that, In step 3, the carbon source is a biomass carbon source.

5. The method for preparing a shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 1, characterized in that, In step 2, the mass ratio of hydrophilic silica nanospheres to toluene solution is 1:5; the molar ratio of hydrophilic silica nanospheres, triethylamine, and methyltrimethoxysilane is 5:1:

1.

6. The method for preparing a shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 1, characterized in that, In step 3, Ni-M x O y The mass ratio of the SiO2 bimetallic composite material, the oil phase, and the carbon source is 1:20:

9.

7. A shell-core structured catalyst for methane-carbon dioxide reforming to syngas prepared by the method of claim 1, characterized in that, It has a multi-shell structure, in which a large sphere encapsulates multiple smaller spheres, and each smaller sphere encapsulates metallic Ni and M. x O y Both the large and small spheres are porous hollow carbon spheres.

8. The shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 7, characterized in that, By mass percentage, the carbon content in the multi-core-shell structure is 75–94 wt%, the metallic Ni content is 5–15 wt%, and M... x O y The mass percentage is 1~10wt%.

9. The shell-core structure catalyst for methane-carbon dioxide reforming to syngas according to claim 7, characterized in that, Catalyst binding index G RI Reaching 95, strength SI4 25 >95%, thermal stability TS +6 >95%.

10. The application of the shell-core structure catalyst for methane-carbon dioxide reforming to syngas as described in claim 7, characterized in that, It is used to catalyze the reforming of methane and carbon dioxide to produce syngas.

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