A MnCeOx composite material and preparation method and its application in biomass photothermal catalytic reforming reaction

Abstract

The present invention provides a MnCeOx composite material, a preparation method, and its application in biomass photothermal catalytic reforming reactions, belonging to the field of catalysts. The present invention provides a MnCeOx composite material comprising MnCeOx nanowires and single Ni atoms supported on the MnCeOx. The active component in the MnCeOx composite material of the present invention exists in single-atom form, which increases the contact area between the active component (the Ni single atom) and the reactants, improving the directional hydrogen production activity of macromolecular volatiles and the efficiency of hydrogen production from biomass pyrolysis. Oxygen vacancies in the MnCeOx composite material modulate the electronic structure of the MnCeOx composite material and provide active sites, further improving the directional hydrogen production activity of macromolecular volatiles and the efficiency of hydrogen production from biomass pyrolysis.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a MnCeOx composite material and a preparation method thereof, and application thereof in a biomass photothermal catalytic reforming reaction. Background Art

[0002] Hydrogen is not only a clean fuel but also a vital industrial raw material, widely used in energy, chemical, and other fields. Biomass pyrolysis and catalytic steam reforming hydrogen production technology not only produces hydrogen but also effectively addresses issues such as tar produced during the pyrolysis process, offering significant application value.

[0003] Catalysts are key to enhancing the activity of biomass pyrolysis steam reforming for hydrogen production. In recent years, research has focused on developing highly efficient and durable catalysts. Common catalysts consist of two components: an active phase and a support. The active phase primarily includes alkali metals, alkaline earth metals, precious metals, and transition metals; the support primarily includes carbon materials, metal oxides, composite metal oxides, hydrotalcite-like materials, and perovskites. Currently, the active phase of common catalysts is typically metal particles, with only surface atoms participating in the reaction. The reactivity of the metal atoms is not fully utilized, resulting in limited catalytic performance. Summary of the Invention

[0004] The present invention provides a MnCeOx composite material and a preparation method thereof, and application thereof in a biomass photothermal catalytic reforming reaction. The MnCeOx composite material provided by the present invention has high catalytic activity in the photothermal catalytic reforming reaction.

[0005] The present invention provides a MnCeOx composite material, comprising MnCeOx nanowires and Ni single atoms supported on the MnCeOx.

[0006] Preferably, the method for preparing the MnCeOx nanowires comprises the following steps:

[0007] Mixing permanganate, cerium salt, ethylene glycol and water and performing a hydrothermal reaction to obtain the MnCeOx nanowires;

[0008] Alternatively, permanganate, cerium salt, ethylene glycol and water are mixed and subjected to a hydrothermal reaction to obtain preliminary MnCeOx nanowires;

[0009] Mixing the preliminary MnCeOx nanowires with a cerium salt solution to perform ion exchange to obtain the MnCeOx nanowires;

[0010] or mixing permanganate, ethylene glycol and water and performing a hydrothermal reaction to obtain the MnOx nanowires;

[0011] Mixing the MnOx nanowires with a cerium salt solution to perform ion exchange to obtain the MnCeOx nanowires;

[0012] The temperature of the hydrothermal reaction is 120° C. and the time is 3 hours.

[0013] Preferably, after the hydrothermal reaction, the method further comprises:

[0014] The product obtained by the hydrothermal reaction is post-treated and the obtained nanowires are mixed with a solution of a second cerium salt. The obtained mixture is then washed and filtered, and the wet nanowires obtained by filtration are dried to obtain the MnCeOx nanowires.

[0015] Preferably, the molar ratio of Mn element to Ce element in the MnCeOx nanowires is 1-20:1.

[0016] Preferably, the loading amount of the Ni single atom is 1-5 wt%.

[0017] Preferably, the length of the MnCeOx nanowire is 3-5 μm and the diameter is 5-20 nm.

[0018] The present invention also provides a method for preparing the MnCeOx composite material described in the above technical solution, comprising the following steps:

[0019] The MnCeOx nanowire dispersion is mixed with the Ni single atom suspension and then post-treated to obtain a precursor of the MnCeOx composite material;

[0020] The MnCeOx composite material precursor is calcined under a protective atmosphere to obtain the MnCeOx composite material.

[0021] Preferably, the method for preparing the dispersion of Ni single atoms comprises the following steps:

[0022] Dissolving nickel salt in a polyvinyl alcohol-ethanol-water mixed solvent, adding a reducing agent to the obtained solution for reduction, and obtaining a suspension of the Ni single atom;

[0023] The volume ratio of ethanol to water in the polyvinyl alcohol-ethanol-water mixed solvent is 1-2:1, and the concentration of polyvinyl alcohol is 0.1-1.0 g / L.

[0024] Preferably, the calcination temperature is 500-900° C., and the holding time is 1-6 hours.

[0025] The present invention also provides the use of the MnCeOx composite material described in the above technical solution or the MnCeOx composite material prepared by the preparation method described in the above technical solution as a catalyst in the photothermal catalytic reforming reaction of biomass, biomass tar or biomass tar model compound.

[0026] The coupling effect of oxygen defects and single atoms improves the directional hydrogen production activity and the efficiency of hydrogen production by biomass pyrolysis: the active components in the MnCeOx composite material of the present invention exist in the form of single atoms, which increases the contact area between the active components (Ni single atoms) and the reactants, thereby improving the directional hydrogen production activity of large molecular volatiles and the efficiency of hydrogen production by biomass pyrolysis; the oxygen defects in the MnCeOx composite material regulate the electronic structure of the MnCeOx composite material and provide active sites, further improving the directional hydrogen production activity of large molecular volatiles and the efficiency of hydrogen production by biomass pyrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the growth process of Ni single atom modified MnCeOx nanowires. DETAILED DESCRIPTION

[0028] The present invention provides a MnCeOx composite material, comprising MnCeOx nanowires and Ni single atoms supported on the MnCeOx.

[0029] In the present invention, the molar ratio of Mn element to Ce element in the MnCeOx nanowire is preferably 1-10:1. In a specific embodiment of the present invention, the molar ratio of Mn element to Ce element in the MnCeOx nanowire can be 10:1, 9:1, 8:1, 7:1, 6:1, 4:1, 2:1 or 1:1; the loading amount of the Ni single atom is 1-5 wt%; the length of the MnCeOx nanowire is 3-5 μm, and the diameter is 5-20 nm; and x is preferably 1-2.

[0030] In the present invention, there are three preferred methods for preparing the MnCeOx nanowires.

[0031] The following describes the first method for preparing MnCeOx nanowires:

[0032] In the present invention, the method for preparing the MnCeOx nanowires preferably comprises the following steps:

[0033] The MnCeOx nanowires are obtained by mixing permanganate, cerium salt, ethylene glycol and water and performing a hydrothermal reaction.

[0034] In the present invention, the mixing preferably includes first mixing permanganate, cerium salt and part of water to obtain a first aqueous solution; second mixing ethylene glycol and remaining water to obtain a second aqueous solution; and dropwise adding the second aqueous solution to the first aqueous solution.

[0035] In the present invention, the molar ratio of the manganese element in the permanganate to the cerium element in the cerium salt is preferably 1-20:1. In a specific embodiment of the present invention, the molar ratio of the manganese element in the permanganate to the cerium element in the first cerium salt can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1 or 19:1; the permanganate preferably includes potassium permanganate and / or sodium permanganate; and the cerium salt preferably includes cerium nitrate.

[0036] In the present invention, the ratio of the amount of manganese element in the permanganate to the amount of water is preferably 1 mmol:3 mL.

[0037] In the present invention, the volume ratio of the partial water to the remaining water is preferably 3:1; the volume ratio of the ethylene glycol to the remaining water is preferably 1:40. Ethylene glycol acts as a mild reducing agent to reduce the high-valent metal ion Mn 7+ Partial reduction causes charge imbalance and forms oxygen vacancies. In addition, during the synthesis of metal oxides, the reducing effect of ethylene glycol may cause surface oxygen to detach from the lattice, forming oxygen vacancies. Ethylene glycol is also a morphology regulator, promoting the formation of nanowires.

[0038] The present invention has no special requirements for the rate of the dropwise addition, and can be added drop by drop. The dropwise addition method of the present invention can prevent the liquid from being ejected due to the intense heat release during the reaction.

[0039] In the present invention, the temperature of the hydrothermal reaction is preferably 120° C., and the time is preferably 3 h.

[0040] After the hydrothermal reaction, the present invention preferably further comprises:

[0041] The product obtained by the hydrothermal reaction is post-treated to obtain the MnCeOx nanowires.

[0042] In the present invention, the post-treatment preferably includes: filtering the product obtained from the hydrothermal reaction, and then washing the obtained solid and drying it.

[0043] The following is a second method for preparing MnCeOx nanowires:

[0044] The permanganate, cerium salt, ethylene glycol and water were mixed and subjected to a hydrothermal reaction to obtain preliminary MnCeOx nanowires;

[0045] The preliminary MnCeOx nanowires are mixed with a cerium salt solution to perform ion exchange to obtain the MnCeOx nanowires.

[0046] The invention mixes permanganate, cerium salt, ethylene glycol and water and then performs hydrothermal reaction to obtain preliminary MnCeOx nanowires.

[0047] In the present invention, the mixing, the molar ratio of the manganese element in the permanganate to the cerium element in the cerium salt, the type of permanganate, the type of cerium salt, the ratio of the amount of manganese element in the permanganate to the amount of water, the volume ratio of the water to the remaining water, the volume ratio of ethylene glycol to the remaining water, the temperature of the hydrothermal reaction, the time of the hydrothermal reaction, and the post-treatment are preferably the same as those in the first method for preparing MnCeOx nanowires and are not described in detail here.

[0048] After obtaining the preliminary MnCeOx nanowires, the present invention mixes the preliminary MnCeOx nanowires with a cerium salt solution to perform ion exchange to obtain the MnCeOx nanowires.

[0049] In the present invention, the ratio of the preliminary MnCeOx nanowires to the cerium salt solution is preferably 1 g:25 mL, and the concentration of the cerium salt solution is preferably 0.05 mol / L; the cerium salt in the cerium salt solution preferably includes cerium nitrate.

[0050] In the present invention, the ion exchange is preferably carried out under stirring, the temperature of the ion exchange is preferably room temperature, and the time is preferably 2 hours. During the ion exchange process, cerium ions are used to replace part of the Mn in the preliminary MnCeOx with Ce.

[0051] After the ion exchange is completed, the present invention performs post-treatment on the obtained product. The post-treatment preferably includes washing and filtering the obtained product, and drying the wet nanowires obtained by filtration to obtain the MnCeOx nanowires.

[0052] Washing can remove metal ions adsorbed on the surface.

[0053] The third method for preparing MnCeOx nanowires is introduced below:

[0054] In the present invention, the method for preparing the MnCeOx nanowires preferably comprises the following steps:

[0055] mixing permanganate, ethylene glycol and water and performing a hydrothermal reaction to obtain the MnOx nanowires;

[0056] The MnOx nanowires are mixed with a cerium salt solution to perform ion exchange to obtain the MnCeOx nanowires.

[0057] The invention mixes permanganate, ethylene glycol and water and then performs a hydrothermal reaction to obtain the MnOx nanowires.

[0058] In the present invention, the mixing preferably includes first mixing permanganate with part of water to obtain a first aqueous solution; second mixing ethylene glycol and the remaining water to obtain a second aqueous solution; and dropwise adding the second aqueous solution to the first aqueous solution.

[0059] In the present invention, the molar ratio of the manganese element in the permanganate to the cerium element in the cerium salt solution is preferably 1-20:1. In a specific embodiment of the present invention, the molar ratio of the manganese element in the permanganate to the cerium element in the cerium salt solution may be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1 or 19:1; the permanganate preferably comprises potassium permanganate and / or sodium permanganate; and the cerium salt in the cerium salt solution preferably comprises cerium nitrate.

[0060] In the present invention, the ratio of the amount of manganese element in the permanganate to the amount of water is preferably 1 mmol:3 mL.

[0061] In the present invention, the volume ratio of the partial water to the remaining water is preferably 3:1; the volume ratio of the ethylene glycol to the remaining water is preferably 1:40. Ethylene glycol acts as a mild reducing agent to reduce the high-valent metal ion Mn 7+ Partial reduction causes charge imbalance and forms oxygen vacancies. In addition, during the synthesis of metal oxides, the reducing effect of ethylene glycol may cause surface oxygen to detach from the lattice, forming oxygen vacancies. Ethylene glycol is also a morphology regulator, promoting the formation of nanowires.

[0062] The present invention has no special requirements for the rate of the dropwise addition, and can be added drop by drop. The dropwise addition method of the present invention can prevent the liquid from being ejected due to the intense heat release during the reaction.

[0063] In the present invention, the temperature of the hydrothermal reaction is preferably 120° C., and the time is preferably 3 h.

[0064] After the hydrothermal reaction, the present invention preferably further comprises:

[0065] The product obtained by the hydrothermal reaction is post-treated to obtain the MnOx nanowires.

[0066] In the present invention, the post-treatment preferably includes: filtering the product obtained from the hydrothermal reaction, and then washing the obtained solid and drying it.

[0067] After obtaining the MnOx nanowires, the present invention mixes the MnOx nanowires with a cerium salt solution to perform ion exchange to obtain the MnOx nanowires.

[0068] In the present invention, the usage ratio of the MnOx nanowires to the cerium salt solution is preferably 1 g:25 mL, and the concentration of the cerium salt solution is preferably 0.05 mol / L; the cerium salt in the cerium salt solution preferably includes cerium nitrate.

[0069] In the present invention, the ion exchange is preferably carried out under stirring, the temperature of the ion exchange is preferably room temperature, and the time is preferably 2 hours. During the ion exchange process, the cerium ions replace part of the Mn in the MnOx nanowires with Ce through ion exchange.

[0070] After the ion exchange is completed, the present invention performs post-treatment on the obtained product. The post-treatment preferably includes washing and filtering the obtained product, and drying the wet nanowires obtained by filtration to obtain the MnCeOx nanowires.

[0071] Washing can remove metal ions adsorbed on the surface.

[0072] The present invention also provides a method for preparing the MnCeOx composite material described in the above technical solution, comprising the following steps:

[0073] The MnCeOx nanowire dispersion is mixed with the Ni single atom suspension and then post-treated to obtain a precursor of the MnCeOx composite material;

[0074] The MnCeOx composite material precursor is calcined under a protective atmosphere to obtain the MnCeOx composite material.

[0075] The invention mixes a dispersion of MnCeOx nanowires with a suspension of Ni single atoms and then performs post-processing to obtain a precursor of the MnCeOx composite material.

[0076] In the present invention, the mixing preferably comprises dropwise adding a dispersion of MnCeOx nanowires to a suspension of Ni atoms. The mixing is preferably performed under stirring, with the stirring speed preferably being 550 to 650 rpm, more preferably 600 rpm. In the present invention, the mixing time is preferably 1 to 3 hours, more preferably 1 hour.

[0077] In the mixing process of the present invention, nickel single atoms are uniformly adsorbed on the surface defects of the MnCeOx nanowires to form a composite material.

[0078] In the present invention, the mass ratio of MnCeOx nanowires to water in the MnCeOx nanowire dispersion is preferably 1:25.

[0079] In the present invention, the volume ratio of the dispersion of MnCeOx nanowires to the suspension of Ni atoms is preferably 1:2.

[0080] In the present invention, the method for preparing the dispersion of Ni single atoms preferably comprises the following steps:

[0081] Dissolving nickel salt in a polyvinyl alcohol-ethanol-water mixed solvent, adding a reducing agent to the obtained solution for reduction, and obtaining a suspension of the Ni single atom;

[0082] In the present invention, the concentration of nickel ions in the dissolving solution is preferably 1 mmol / L, and the nickel salt preferably includes one or more of nickel nitrate, nickel chloride and nickel sulfate.

[0083] In the present invention, the volume ratio of ethanol and water in the polyvinyl alcohol-ethanol-water mixed solvent is preferably 1-2:1, and the concentration of polyvinyl alcohol is preferably 0.1-1.0 g / L. In a specific embodiment of the present invention, the volume ratio of ethanol and water can be 1.2:1, 1.5:1 or 1.8:1, and the concentration of polyvinyl alcohol can be 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L or 0.9 g / L. The hydroxyl groups on the polyvinyl alcohol molecular chain can coordinate with metal salts, and the long-chain molecules form dynamic steric hindrance in the solvent, suppressing the aggregation of metal ions and forming uniformly dispersed metal ions in the solution. The ethanol and water mixed solution can appropriately adjust the polarity and surface tension of the solution, optimize the precursor dissolution behavior, and thus control the dispersion state of the metal. After rapid reduction with a reducing agent, single atoms are formed instead of agglomerating into metal particles.

[0084] In the present invention, the molar ratio of the reducing agent to the nickel ions in the nickel salt is preferably 10-15:1; the reducing agent preferably includes borohydride, and the borohydride preferably includes sodium borohydride or potassium borohydride.

[0085] In the present invention, the reduction temperature is preferably room temperature, and the reduction time is preferably 10 minutes.

[0086] In the present invention, the post-treatment preferably includes washing, filtering and drying the reduction product to obtain the precursor of the MnCeOx composite material.

[0087] After obtaining the precursor of the MnCeOx composite material, the present invention calcines the MnCeOx composite material precursor under a protective atmosphere to obtain the MnCeOx composite material.

[0088] In the present invention, the protective atmosphere is preferably a nitrogen atmosphere. In the present invention, calcination is carried out under a protective atmosphere to prevent the oxidation of nickel atoms to form metal oxides, thereby reducing the activity of the nickel.

[0089] In the present invention, the calcination temperature is preferably 500-900°C, and the holding time is preferably 1-4 hours. In specific embodiments, the calcination temperature can be 600°C, 700°C, or 800°C, and the holding time can be 2 hours or 3 hours. The present invention utilizes calcination to anchor single nickel atoms to the surface of the MnCeOx nanowires, thereby securing them.

[0090] The present invention also provides the use of the MnCeOx composite material described in the above technical solution or the MnCeOx composite material prepared by the preparation method described in the above technical solution as a catalyst in the photothermal catalytic reforming reaction of biomass, biomass tar or biomass tar model compound.

[0091] In the present invention, the temperature of the photothermal catalytic reforming reaction is preferably 500~800℃. In a specific embodiment of the present invention, the temperature of the photothermal catalytic reforming reaction can be 500℃, 600℃, 700℃ or 800℃, the time is preferably 30min, and the light intensity is preferably a 300W xenon lamp; the heating rate to the temperature of the photothermal catalytic reforming reaction is preferably 10℃ / min.

[0092] In the present invention, the photothermal catalytic reforming reaction of the biomass preferably comprises: placing the biomass and the MnCeOx composite material in a pyrolysis reaction device, introducing protective gas and reforming gas, and performing a photothermal catalytic reforming reaction.

[0093] In the present invention, the biomass preferably includes corn straw; the mass ratio of the biomass to the MnCeOx composite material is preferably 2.5:1, the flow rate of the protective gas is preferably 70 mL / min, and the protective gas preferably includes nitrogen; the flow rate of the integrated gas is preferably 30 mL / min, and the integrated gas preferably includes water vapor.

[0094] The photothermal catalytic reforming reaction of the biomass tar or biomass tar model compound preferably includes:

[0095] Biomass tar or a biomass tar model compound is mixed with a MnCeOx composite material, and then protective gas and reforming gas are introduced to carry out a photothermal catalytic reforming reaction.

[0096] In the present invention, the volume ratio of the biomass tar or biomass tar model compound to the MnCeOx composite material is preferably 1.5 mL:0.5 g, the flow rate of the protective gas is preferably 100 mL / min, and the protective gas preferably includes nitrogen; the flow rate of the reformed gas is preferably 30 mL / min, and the reformed gas preferably includes water vapor.

[0097] The MnCeOx composite material provided by the present invention has good stability and can be reused. When reused, the MnCeOx composite material after the reaction is preferably separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere for 2-3 hours before being put into the next use.

[0098] The following examples describe in detail the MnCeOx composite material and its preparation method as well as its application in the biomass photothermal catalytic reforming reaction provided by the present invention. However, they should not be construed as limiting the scope of protection of the present invention.

[0099] Figure 1 Schematic diagram of the growth process of Ni single atom modified MnCeOx nanowires.

[0100] Example 1

[0101] 20 mmol of potassium permanganate and 5 mmol of cerium nitrate were dissolved in 60 mL of water to obtain solution A1. 0.5 mL of ethylene glycol was dissolved in 20 mL of water to obtain solution B. Solution B was added dropwise to solution A1, and the mixture was hydroheated at 120°C for 3 h. After filtering and washing, the mixture was dried at 60°C for 12 h to obtain MC-5 catalyst.

[0102] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0103] 2g of MC-5 dispersion (2g of powdered MC-5 dispersed in 50mL of water) was added to the suspension and stirred at 600 rpm for 1 hour. The synthesized catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. The 2g catalyst was placed in a quartz boat and calcined in a tube furnace at 500°C for 6 hours under a nitrogen atmosphere to obtain the catalyst (i.e., Ni single-atom-modified MnCeOx nanowires).

[0104] Using toluene, a tar model compound, as the pyrolysis target, the experiment was conducted in a pyrolysis reaction device:

[0105] 0.5 g of catalyst was added to the quartz tube, and nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 100 mL / min. Water vapor was introduced as reforming gas with a water vapor flow rate of 30 ml / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 600 °C, the heating time was 60 min, and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium, and the flow ratio of water vapor to carbon (S / C) was adjusted to 1, 2, 3, 4 and 5, respectively.

[0106] The catalyst has the best catalytic performance when the temperature is 600℃ and S / C is 5. The total pyrolysis gas production is 43mL / min, of which the yields of H2, CO, CO2 and CH4 are 60.3%, 51.8%, 19.6% and 10.2% respectively.

[0107] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0108] Example 2

[0109] Dissolve 20 mmol of potassium permanganate and 2 mmol of cerium nitrate in 60 mL of water to obtain solution A2, and dissolve 0.5 mL of ethylene glycol in 20 mL of water to obtain solution B. Add solution B dropwise into solution A2, hydroheat at 120°C for 3 h, filter, wash, and dry at 60°C for 12 h to obtain MC-2 catalyst.

[0110] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0111] 2g of MC-2 dispersion (2g of powdered MC-2 dispersed in 50mL of water) was added to the suspension and stirred at 600 rpm for 1 hour. The synthesized catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. The 2g catalyst was placed in a quartz boat and calcined in a tube furnace at 500°C for 6 hours under a nitrogen atmosphere to obtain the catalyst (i.e., Ni single-atom-modified MnCeOx nanowires).

[0112] Using toluene, a tar model compound, as the pyrolysis target, the experiment was conducted in a pyrolysis reaction device:

[0113] 0.5 g of catalyst was added to the quartz tube, and nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 100 mL / min. Water vapor was introduced as reforming gas with a water vapor flow rate of 30 ml / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 600 °C, the heating time was 60 min, and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium, and the flow ratio of water vapor to carbon (S / C) was adjusted to 1, 2, 3, 4 and 5, respectively.

[0114] The catalyst has the best catalytic performance when the temperature is 600℃ and S / C is 5. The total pyrolysis gas production is 41mL / min, of which the yields of H2, CO, CO2 and CH4 are 45.7%, 41.2%, 25.6% and 8.7% respectively.

[0115] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0116] Example 3

[0117] 20 mmol of potassium permanganate and 1 mmol of cerium nitrate were dissolved in 60 mL of water to obtain solution A3. 0.5 mL of ethylene glycol was dissolved in 20 mL of water to obtain solution B. Solution B was added dropwise to solution A3, and the mixture was hydroheated at 120°C for 3 h. After filtration and washing, it was dried at 60°C for 12 h to obtain MnCeOx nanowires, which were recorded as MC-1.

[0118] 2 g of MC-1 was dispersed in 50 mL of Ce(NO3)2 solution (0.05 M), stirred for 2 h, and the mixture was washed with deionized water, filtered, and dried at 105 °C for 12 h to obtain MC-C.

[0119] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0120] A MC-C dispersion (2 g MC-C in 50 mL water) was added dropwise to the suspension system and stirred at 600 rpm for 1 hour. The resulting catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. 2 g of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0121] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of the crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added. Nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 70 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperatures were 500°C, 600°C and 700°C, the heating time was 60 min, the heating rate was 10°C / min, and the water vapor flow rate was 30 mL / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation, and the cooling system used circulating water as the cooling medium.

[0122] The catalyst has the best catalytic performance at a temperature of 600°C, and the total pyrolysis gas production is 35.3 mmol / g, of which the synthesis gas production is 22.8 mmol / g, of which hydrogen accounts for 65.3%.

[0123] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0124] Example 4

[0125] Dissolve 20 mmol of potassium permanganate and 1 mmol of cerium nitrate in 60 mL of water to obtain solution A3. Dissolve 0.5 mL of ethylene glycol in 20 mL of water to obtain solution B. Add solution B dropwise to solution A3, hydroheat at 120°C for 3 h, filter, wash, and dry at 60°C for 12 h to obtain MC-1.

[0126] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0127] A MnCeOx nanowire dispersion (2g MC-1 dispersed in 50mL water) was added dropwise to the suspension. The mixture was stirred at 600 rpm for 1 hour. The resulting catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. Two grams of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0128] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of the crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added. Nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 70 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperatures were 500°C, 600°C and 700°C, the heating time was 60 min, the heating rate was 10°C / min, and the water vapor flow rate was 30 mL / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation, and the cooling system used circulating water as the cooling medium.

[0129] The catalyst achieved optimal catalytic performance at 700°C, producing a total pyrolysis gas yield of 31.5 mmol / g, including 20.2 mmol / g of synthesis gas, of which 42.5% was hydrogen. The catalyst was separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being reused.

[0130] Comparative Example 1

[0131] Dissolve 20 mmol of potassium permanganate in 60 mL of water to obtain solution A, and dissolve 0.5 mL of ethylene glycol in 20 mL of water to obtain solution B. Add solution B dropwise into solution A, heat at 120°C for 3 h, filter, wash, and dry at 60°C for 12 h to obtain MnO x Nanowires.

[0132] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0133] Add MnO dropwise into the suspension system x Nanowire dispersion (2g MnO x The nanowires were dispersed in 50 mL of water and stirred at 600 rpm for 1 hour. The synthesized catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. 2 g of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0134] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added and nitrogen was introduced as a protective atmosphere. The nitrogen flow rate was 70 mL / min and the water vapor flow rate was 30 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 500 °C, 600 °C and 700 °C, the heating time was 60 min and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium.

[0135] The catalyst has the best catalytic performance at a temperature of 700°C, and the total pyrolysis gas production is 21.3 mmol / g, of which the synthesis gas production is 13.5 mmol / g, of which hydrogen accounts for 32.5%.

[0136] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0137] Comparative Example 2

[0138] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0139] H-ZSM-5 (Sinopharm Reagent) was added to the suspension and stirred at 600 rpm for 1 hour. The resulting catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. Two grams of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0140] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added and nitrogen was introduced as a protective atmosphere. The nitrogen flow rate was 70 mL / min and the water vapor flow rate was 30 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 500 °C, 600 °C and 700 °C, the heating time was 60 min and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium.

[0141] The catalyst has the best catalytic performance at a temperature of 700°C, and the total pyrolysis gas production is 18.7 mmol / g, of which the synthesis gas production is 15.5 mmol / g, of which hydrogen accounts for 34.5%.

[0142] Comparative Example 3

[0143] Dissolve 20 mmol of potassium permanganate and 1 mmol of cerium nitrate in 60 mL of water to obtain solution A3. Dissolve 0.5 mL of ethylene glycol in 20 mL of water to obtain solution B. Add solution B dropwise to solution A3, hydroheat at 120°C for 3 h, filter, wash, and dry at 60°C for 12 h to obtain MC-1.

[0144] Ferric nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (iron ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a suspension system of single iron atoms.

[0145] A MnCeOx nanowire dispersion (2g MC-1 dispersed in 50mL water) was added dropwise to the suspension. The mixture was stirred at 600 rpm for 1 hour. The resulting catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. Two grams of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0146] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of the crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added. Nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 70 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperatures were 500°C, 600°C and 700°C, the heating time was 60 min, the heating rate was 10°C / min, and the water vapor flow rate was 30 mL / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation, and the cooling system used circulating water as the cooling medium.

[0147] The catalyst achieved optimal catalytic performance at 700°C, producing a total pyrolysis gas yield of 22.8 mmol / g, including 15.1 mmol / g of synthesis gas, of which 30.2% was hydrogen. The catalyst was separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being reused.

[0148] Comparative Example 4

[0149] Dissolve 20 mmol of potassium permanganate in 60 mL of water to obtain solution A, and dissolve 0.5 mL of ethylene glycol in 20 mL of water to obtain solution B. Add solution B dropwise into solution A, heat at 120°C for 3 h, filter, wash, and dry at 60°C for 12 h to obtain MnO x Nanowires.

[0150] Cobalt nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (cobalt ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a suspension system of cobalt single atoms.

[0151] Add MnO dropwise into the suspension system x Nanowire dispersion (2g MnO x The nanowires were dispersed in 50 mL of water and stirred at 600 rpm for 1 hour. The synthesized catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. 2 g of the catalyst was placed in a quartz boat and calcined in a tube furnace at 600°C for 2 hours under a nitrogen atmosphere to obtain the catalyst.

[0152] Corn straw was used as raw material and crushed to 40-60 mesh. 5 g of crushed corn straw was weighed and placed in a pyrolysis reaction device. 2 g of catalyst was added and nitrogen was introduced as a protective atmosphere. The nitrogen flow rate was 70 mL / min and the water vapor flow rate was 30 mL / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 500 °C, 600 °C and 700 °C, the heating time was 60 min and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium.

[0153] The catalyst has the best catalytic performance at a temperature of 700°C. The total pyrolysis gas yield is 21.3 mmol / g, of which the synthesis gas yield is 10.8 mmol / g, of which hydrogen accounts for 28.3%.

[0154] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0155] Comparative Example 5

[0156] 20 mmol of potassium permanganate and 5 mmol of cobalt nitrate were dissolved in 60 mL of water to obtain solution A2. 0.5 mL of ethylene glycol was dissolved in 20 mL of water to obtain solution B. Solution B was added dropwise to solution A2, and the mixture was hydroheated at 120°C for 3 h. After filtration and washing, the mixture was dried at 60°C for 12 h to obtain MCo-5 catalyst.

[0157] Nickel nitrate was dissolved in 100 mL of a PVA / ethanol / water mixed solvent (0.1 g of PVA and a 1:1 volume ratio of ethanol to water) to obtain a salt solution (Ni ion concentration of 1 mmol / L). 0.2 g of NaBH4 was added to the salt solution and reacted at room temperature for 10 minutes to obtain a Ni single-atom suspension system.

[0158] 2g of MCo-5 dispersion (2g of powdered MCo-5 dispersed in 50mL of water) was added to the suspension and stirred at 600 rpm for 1 hour. The synthesized catalyst was then washed with water, filtered, and dried at 105°C for 12 hours. The 2g catalyst was placed in a quartz boat and calcined at 500°C in a tube furnace under a nitrogen atmosphere for 6 hours to obtain the catalyst (i.e., Ni single-atom-modified MnCoOx nanowires).

[0159] Using toluene, a tar model compound, as the pyrolysis target, the experiment was conducted in a pyrolysis reaction device:

[0160] 0.5 g of catalyst was added to the quartz tube, and nitrogen was introduced as a protective atmosphere with a nitrogen flow rate of 100 mL / min. Water vapor was introduced as reforming gas with a water vapor flow rate of 30 ml / min. The light intensity was set to a 300 W xenon lamp, the pyrolysis temperature was 600 °C, the heating time was 60 min, and the heating rate was 10 °C / min. The high-temperature pyrolysis gas generated during the pyrolysis process was transported to the cooling system through insulation. The cooling system used circulating water as the cooling medium, and the flow ratio of water vapor to carbon (S / C) was adjusted to 1, 2, 3, 4 and 5, respectively.

[0161] The catalyst has the best catalytic performance when the temperature is 600℃ and S / C is 5. The total pyrolysis gas production is 38mL / min, of which the yields of H2, CO, CO2 and CH4 are 35.8%, 37.2%, 20.8% and 6.5% respectively.

[0162] The catalyst after the reaction is separated, washed, dried, and heat-treated at 500°C in a hydrogen atmosphere before being put into next use.

[0163] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A MnCeOx composite material, characterized in that: It includes MnCeOx nanowires and Ni single atoms supported on MnCeOx; The preparation method of the MnCeOx composite material comprises the following steps: The MnCeOx nanowire dispersion is mixed with the Ni single atom suspension and then post-treated to obtain a precursor of the MnCeOx composite material; calcining the MnCeOx composite material precursor under a protective atmosphere to obtain the MnCeOx composite material; The preparation method of the Ni single atom dispersion comprises the following steps: Dissolving nickel salt in a polyvinyl alcohol-ethanol-water mixed solvent, adding a reducing agent to the obtained solution for reduction, and obtaining a suspension of the Ni single atom; The volume ratio of ethanol to water in the polyvinyl alcohol-ethanol-water mixed solvent is 1-2:1, and the concentration of polyvinyl alcohol is 0.1-1.0 g / L.

2. The MnCeOx composite material according to claim 1, characterized in that The method for preparing the MnCeOx nanowires comprises the following steps: Mixing permanganate, cerium salt, ethylene glycol and water and performing a hydrothermal reaction to obtain the MnCeOx nanowires; Alternatively, permanganate, cerium salt, ethylene glycol and water are mixed and subjected to a hydrothermal reaction to obtain preliminary MnCeOx nanowires; The preliminary MnCeOx nanowires were mixed with a cerium salt solution for ion exchange. After the ion exchange was completed, the resulting product was washed and filtered, and the wet nanowires obtained by filtration were dried to obtain the MnCeOx nanowires; The temperature of the hydrothermal reaction is 120° C. and the time is 3 hours.

3. The MnCeOx composite material according to any one of claims 1 to 2, characterized in that The molar ratio of the Mn element to the Ce element in the MnCeOx nanowires is 1-20:

1.

4. The MnCeOx composite material according to claim 1, characterized in that The loading amount of the Ni single atom is 1-5 wt %.

5. The MnCeOx composite material according to any one of claims 1 to 2, characterized in that: The length of the MnCeOx nanowire is 3-5 μm, and the diameter is 5-20 nm.

6. The method for preparing the MnCeOx composite material according to any one of claims 1 to 5, characterized in that: The following steps are involved: The MnCeOx nanowire dispersion is mixed with the Ni single atom suspension and then post-treated to obtain a precursor of the MnCeOx composite material; calcining the MnCeOx composite material precursor under a protective atmosphere to obtain the MnCeOx composite material; The preparation method of the Ni single atom dispersion comprises the following steps: Dissolving nickel salt in a polyvinyl alcohol-ethanol-water mixed solvent, adding a reducing agent to the obtained solution for reduction, and obtaining a suspension of the Ni single atom; The volume ratio of ethanol to water in the polyvinyl alcohol-ethanol-water mixed solvent is 1-2:1, and the concentration of polyvinyl alcohol is 0.1-1.0 g / L.

7. The preparation method according to claim 6, characterized in that The calcination temperature is 500-900° C., and the holding time is 1-6 hours.

8. Use of the MnCeOx composite material according to any one of claims 1 to 5 or the MnCeOx composite material prepared by the preparation method according to any one of claims 6 to 7 as a catalyst in the photothermal catalytic reforming reaction of biomass, biomass tar or a biomass tar model compound.

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