阅读说明：本技术 一种等离子体-热耦合甲烷和水蒸气重整制甲醇的方法 (Method for preparing methanol by reforming plasma-thermal coupling methane and steam ) 是由 易颜辉 郝英姿 于 2021-09-26 设计创作，主要内容包括：本发明涉及一种等离子体-热耦合甲烷和水蒸气重整制甲醇的方法,属于甲烷资源利用和等离子体化学合成技术领域。该金属负载型催化剂的活性组分为Cu,载体包括SiO-(2)、Al-(2)O-(3)、ZrO-(2)、CeO-(2)、TiO-(2)、Fe-(2)O-(3)、以及沸石分子筛；活性组分Cu在催化剂中所占的重量百分比为1％-10％。放电反应区维持在170℃、0.1MPa条件下,甲烷与水蒸气的比例为1:4,甲醇的选择性可达58％。该方法条件温和,所用的催化剂高度分散且催化活性稳定,属于一步法直接合成工艺,方法简单,原料廉价,无污染。(The invention relates to a method for preparing methanol by reforming plasma-thermal coupling methane and steam, belonging to the technical field of methane resource utilization and plasma chemical synthesis. The active component of the metal-loaded catalyst is Cu, and the carrier comprises SiO 2 、Al 2 O 3 、ZrO 2 、CeO 2 、TiO 2 、Fe 2 O 3 And zeolite molecular sieves; the weight percentage of the active component Cu in the catalyst is 1-10%. The discharge reaction zone is maintained at 170 ℃ and 0.1MPa, the ratio of methane to water vapor is 1:4, and the selectivity of methanol can reach 58%. The method has mild conditions, high dispersion of the used catalyst and stable catalytic activity, belongs to a one-step direct synthesis process, and has the advantages of simple method, cheap raw materials and no pollution.)

1. A method for preparing methanol by reforming plasma-thermal coupling methane and steam is characterized in that methane, steam and argon are introduced into a dielectric barrier discharge reactor, methane molecules and water molecules are activated through dielectric barrier discharge, and the activated methane molecules and water molecules are converted into methanol under the action of a metal supported catalyst; wherein the metal-loaded catalyst comprises an active component and a carrier, the active component is Cu, Ni and Zr, and the carrier is SiO₂Or zeolite molecular sieve, the active component accounts for 1-20% of the metal-loaded catalyst by mass percent; the molar ratio of the methane to the water vapor is 1:0.1-10, the retention time of the mixed gas in the reaction zone is 0.01-100s, the high-voltage alternating current power supply is adopted for dielectric barrier discharge, the power frequency is 1kHz-50kHz, the discharge pressure is-0.06 MPa-0.2MPa, and the reaction temperature is 100-.

2. The method for preparing methanol by plasma-thermally coupling methane and steam reforming according to claim 1, wherein the method is realized by adopting the following dielectric barrier discharge reactors:

the dielectric barrier discharge reactor is a linear-cylinder reactor, the reactor is cylindrical, the outside of the reactor is coated with aluminum foil, and then metal wires are wound on the outside of the aluminum foil to be used as a grounding electrode; the upper end of the cylinder is provided with an upper end enclosure with a central hole, and a metal rod is arranged along the axis of the reactor through the central hole and is used as a high-voltage electrode; the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 0.3-30 mm; the cylindrical reactor is made of a single-layer dielectric insulating material;

the upper end of the reactor is provided with methane, water vapor and argon inlets which are positioned above the discharge area, the lower end of the reactor is connected with a collector, the collector is arranged in a cold trap, and the rear end of the collector is connected with a tail gas outlet; the catalyst is arranged in a discharge area in the reactor, and a catalyst bed layer is supported by a quartz sand plate; and a heating furnace is arranged outside the discharge area and is used as a heat preservation device.

3. A process for the plasma-thermal coupling of methane and steam reforming for the production of methanol according to claim 1 or 2, characterized in that the residence time of the mixed gas in the reaction zone is 0.1 to 10s, the molar ratio of methane to steam is 1:2 to 6; the discharge pressure is 0.1MPa, and the reaction temperature is 150-250 ℃.

4. A method of plasma-thermally coupling methane and steam reforming to methanol according to claim 1 or 2, wherein said active component is present in the catalyst in an amount of 3-10% by weight.

5. A method of plasma-thermally coupling methane and steam reforming to methanol as claimed in claim 3, wherein said active component is present in the metal-supported catalyst in an amount of 3-10% by weight.

6. A method of plasma-thermally coupling methane and steam reforming for methanol as claimed in claim 1, 2 or 5, wherein the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 1-5 mm; the dielectric barrier discharge adopts a high-voltage alternating current power supply, and the power supply frequency is 12kHz-15 kHz.

7. A process for the plasma-thermal coupling of methane and steam reforming for the production of methanol as claimed in claim 3, wherein the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 1-5 mm; the dielectric barrier discharge adopts a high-voltage alternating current power supply, and the power supply frequency is 12kHz-15 kHz.

8. A method of plasma-thermally coupling methane and steam reforming for methanol as claimed in claim 4, wherein the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 1-5 mm; the dielectric barrier discharge adopts a high-voltage alternating current power supply, and the power supply frequency is 12kHz-15 kHz.

9. The method for preparing methanol by plasma-thermal coupling methane and steam reforming as claimed in claim 1, 2, 5, 7 or 8, wherein when dielectric barrier discharge is adopted, the high voltage electrode and the grounding electrode are made of copper, iron, tungsten, aluminum or stainless steel; the reactor is made of quartz glass, hard glass, alumina ceramic, polytetrafluoroethylene or nonmetal composite materials.

10. The method of claim 6, wherein when a dielectric barrier discharge is used, the high voltage electrode and the ground electrode are made of copper, iron, tungsten, aluminum or stainless steel; the blocking medium is made of quartz glass, hard glass, alumina ceramic, polytetrafluoroethylene or nonmetal composite materials.

Technical Field

The invention belongs to the technical field of methane resource utilization and plasma chemical synthesis, and relates to a method for preparing methanol by catalyzing methane steam reforming with plasma, a metal-loaded catalyst and a preparation method thereof.

Background

Methane and natural gas have main components and abundant reserves, and are important carbon resources. Meanwhile, methane is also a greenhouse gas. The methanol is liquid at normal temperature and normal pressure, is convenient to store and transport, is an important chemical raw material, and can be used for producing high value-added chemical products such as olefin, aromatic hydrocarbon, gasoline additive methyl tert-butyl ether and the like. Thus, the conversion of methane to methanol is of great interest.

The industry mainly uses a two-step method to convert methane into methanol, and the first step is to mix methane and H under the high temperature condition of more than 800 DEG C₂Production of synthesis gas (CO and H) by O reforming reaction₂) (ii) a The second step is that the synthesis gas is synthesized into the methanol under the action of the Cu-Zn-Al catalyst at the temperature of about 250 ℃ and under the condition of 100 atmospheric pressures. The key research is on the modification of the Ni-based catalyst, the addition of an auxiliary agent is used for improving the activity, the high-temperature thermal stability and the carbon and coke resistance of the catalyst, and the catalyst with high activity under the low-temperature condition is developed.

The publication patent CN10738162A (patent No. CN201710187240.0) synthesizes Ni @ Al with a core-shell structure₂O₃The catalyst utilizes the nanometer confinement effect of the core-shell structure catalyst, obviously improves the dispersion degree of Ni, prevents Ni nano particles from aggregating under the high-temperature condition, and improves the carbon deposition resistance of the catalyst.

The methanol can be further prepared from the synthesis gas through Fischer-Tropsch synthesis, and the current published patent research mainly focuses on the aspect of modifying the morphology of the Cu-Zn-Al catalyst;

the catalyst synthesized by the patent publication CN112023933A (patent No. CN202010803153.5) takes hydrotalcite as a template, and utilizes the characteristic that the hydrotalcite can be hydrated in situ after being calcined to realize the ordered distribution of Cu and Zn components on a lamellar structure. The active components are not easy to agglomerate in the high-temperature reaction process by utilizing the confinement effect of the hydrotalcite lamellar structure, and the heat-resistant stability is better.

The methane can be converted into the methanol by adopting methods such as thermal catalysis, photocatalysis, electrocatalysis, biomass conversion and the like.

The reactions for preparing methanol by methane oxidation can be divided into homogeneous catalysis and heterogeneous catalysis. Homogeneous catalysis is mostly a sulfate-based reaction system, namely sulfuric acid is used as a reaction medium, noble metals such as Pt, Pd, Hg, Rh and the like are used as central atoms to activate methane and break C-H bonds, and then the activated methane and the C-H bonds are reactedCH with coordinated central atoms₃The functionalization is methanol.

Publication J.Am.chem.Soc.2016,138, 12395-12400 reports potassium tetrachloroplatinate (K)₂PtCl₄) Is a catalyst with extremely high activity, strong selectivity and stability, and achieves TOF exceeding 25000h in 20 percent fuming sulfuric acid^-1The selectivity is higher than 98%.

For heterogeneous catalysis, various catalytic materials have been developed rapidly in recent years, Au-Pd alloy catalyst and H₂O₂The coupling can oxidize methane to methanol with high selectivity (more than 90 percent) under the condition of low temperature.

The publication "Science, 2020,367, 193-197" reports a "molecular fence" strategy, H₂And O₂In-situ synthesis of H on catalyst with Au-Pd alloy nanoparticles fixed on molecular sieve₂O₂Remarkably improve H₂O₂The utilization rate of (1) is 17.3 percent under mild conditions (70 ℃), the selectivity of methanol is 92 percent, which is inspired by the active sites of di-iron and di-copper in methane monooxygenase, and O is used₂Or N₂Cu-based or Fe-based zeolite catalysts with O as the oxidant are widely used for the oxidation of methane to methanol. For Cu molecular sieve catalysts, first at O₂Or high-temperature (> 450 ℃) activation is carried out in the air; the activated catalyst reacts with methane at low temperature (200 ℃) to generate adsorbed CH₃An O species; finally, the methanol is desorbed by solvent or steam extraction to obtain the product. For Fe-based molecular sieve catalysts, N₂O firstly, Fe on the surface of the Fe-based molecular sieve^IIOxidation of species to Fe^IIIThe species, then reacts with methane to break its C-H bonds and produce methanol in an adsorbed state. In order to avoid deep oxidation of methanol, Cu-based and Fe-based molecular sieve catalysts are mainly used for preparing methanol by methane oxidation through multi-step non-catalytic stoichiometric reaction.

The publication Angew. chem. int. Ed.2016,55, 5467-5471 reports that Cu-Mordenite catalysts can increase methanol yield by increasing the partial pressure of methane during isothermal chemical cycling. The yield of methanol was 56.2. mu. mol/g at a methane pressure of 37bar_cat

The publication ACS Catal.2017,7,1403-1412 proposes that Cu-Mordenite molecular sieve prepared by the solid-state ion exchange method can generate more different active sites than catalyst prepared by the liquid-state ion exchange method, thereby increasing O₂Efficiency of catalytic methane conversion.

The publication J.Am.chem.Soc.2017, 139,14961-14975 reports that Cu-SSZ-13 catalyst realizes 107 mu mol/g by prolonging the activation time and increasing the partial pressure of methane_catYield of methanol. After four cycles, the yield reaches 125 mu mol/g_cat。

The published literature "Science, 2021,373, 327-331-" compares the reaction results of Fe-BEA type molecular sieve and Fe-CHA type molecular sieve, and the detailed spectral characterization and density functional theory calculation of the reaction intermediate show that the small-pore diffusion resistance is not favorable for the premature release of CH from the active site after C-H activation₃Free radicals, thereby promoting the formation of methanol by the free radical recombination.

The patent publication CN 111333487A (patent No. CN202010298935.8) discloses a method for preparing methanol by photocatalytic oxidation of methane, which utilizes composite Au/ZnO as a photocatalyst, and introduces methane and oxygen, and replaces the irradiation of an ultraviolet region with full-spectrum irradiation, thus meeting the energy requirement in the reaction, avoiding the methanol generated by too high light energy input being decomposed and oxidized into formaldehyde, and the selectivity of the methanol reaching 100 percent.

Patent publication CN101775614A (patent No. CN201010106288.2) proposes to use a closed electrolytic cell, to use hollow porous graphite as an anode and stainless steel as a cathode, to directly introduce methane gas into the porous graphite anode, to switch on the current, to generate methanol in the electrolyte, and to recycle NaOH, NaCl or NaF which constitutes the electrolyte in the whole process without consumption.

Published patent No. CN1580269A (No. CN03143797.4) discloses a method for preparing methanol by biocatalysis of methane. The method comprises the steps of reacting methane-oxidizing bacterial cells serving as a catalyst and a mixed gas of methane, carbon dioxide and oxygen serving as a raw material gas at the temperature of 32-40 ℃ and the pressure of 0-1.2MPa to obtain a methanol aqueous solution. Solves the problems of cell activity reduction caused by the consumption of coenzyme NADH and reaction incapability of continuous proceeding caused by intermittent regeneration or addition of other exogenous electron donors, and realizes the in-situ regeneration of the coenzyme NADH in a reaction system.

The current widely studied technologies have many defects and shortcomings: the methane is converted into the methanol by adopting a two-step method in industry, and the high operation investment, equipment investment and equipment maintenance cost are caused by the high-temperature and high-pressure condition; in homogeneous catalysis, the catalyst has high cost, the reaction medium has strong corrosivity, the equipment requirement is strict, and the product separation is difficult. Cannot be obtained with high methane conversion and high methanol selectivity in heterogeneous catalysis, and most of the catalyst is H₂O₂Or N₂O is an oxidizing agent which can achieve the purpose of low-temperature oxidation, but is expensive. In the photoelectrocatalysis system, the yield of the methanol is lower.

So far, there are very few publications and patents on the direct production of methanol from methane and steam in one step.

The publication 'Science, 2017, 356, 523-527' proposes that water is used for selectively carrying out anaerobic oxidation on methane to prepare methanol, and a Cu/MOR catalyst and an oxidant H are used in an isothermal chemical circulation mode₂The O combination realizes the oxygen-free preparation of methanol, and the selectivity of the methanol is as high as 97 percent. However, the reaction is limited by thermodynamics and has been questioned in many ways.

The publication J.Am.chem.Soc.2020,142,11962-11966 proposes a process for partial oxidation of methane to methanol in a continuous flow reactor using a Cu-SSZ-13 catalyst, the main source of O being H₂O instead of O₂. In the absence of molecular oxygen and use¹⁸This process was confirmed by experiments with O-labelled water.

The plasma is taken as the fourth state of matter and contains abundant high-energy electrons which can enable inert raw material molecules (methane and H) to be separated through inelastic collision₂O) to be activated into active species such as radicals, excited atoms and ions. At present, low temperature plasma technology has been widely applied to the conversion of methane, but most of the products are synthesis gas or hydrocarbon compounds. So far, only a few published documents and published patents report the conversion of methane and water vapor in low-temperature plasmaMethanol was detected in the gas reaction.

The publication "phys. chem. phys.,2012,14, 3444-3449" suggests that methanol is the main product when argon spiked with water and methane is discharged at 11K and condensed into a solid matrix. By using²H、¹⁷O and¹⁸experiments with O-labelled compounds have shown that the mechanism for methanol production may be the insertion of excited oxygen atoms in the 1D state into the C-H of the methane molecule.

The publication Journal of Environmental Engineering and Technology, 2013,2,35-39, reports a method for DBD plasma conversion of methane and water vapor, proposing selectivity of methanol to methane and H₂The mixing ratio of O is very sensitive when methane is mixed with H₂The selectivity to methanol was about 20% after mixing O at a gas mixing ratio of 1: 5.

Publication patent No. CN111974393A (patent No. CN202010968347.0) discloses a preparation method of a catalyst for preparing methanol by low-temperature plasma-optical coupling of methane and a method for preparing methanol. The plasma generates high-energy electrons to activate methane at normal temperature and normal pressure, and the light generated by the plasma is utilized by adding a Cu-C catalyst to activate H₂And O, further improving the yield of the methanol.

The disclosed method for preparing methanol from methane by plasma catalysis often has the problems of excessive oxidation and low yield of methanol.

In summary, the prior publications and publications relate to the one-step preparation of methanol by reforming methane with steam, which has the problems of thermodynamic limitation, low methanol yield or harsh reaction conditions, and the influence of catalytic materials on the reaction result is not basically related. Therefore, the method for preparing the methanol by reforming the methane and the steam in one step by utilizing the synergistic effect of the plasma and the catalyst under the conditions of normal temperature and normal pressure has a very high application prospect.

Disclosure of Invention

The invention aims to provide a method for preparing methanol by plasma-thermal coupling methane and steam reforming.

The technical scheme of the invention is as follows:

plasma-thermocoupleIntroducing methane, steam and argon into a dielectric barrier discharge reactor, activating methane molecules and water molecules through dielectric barrier discharge, and converting the activated methane molecules and water molecules into methanol under the action of a metal supported catalyst; wherein the metal-loaded catalyst comprises an active component and a carrier, the active component is Cu, Ni and Zr, and the carrier is SiO₂Or zeolite molecular sieve, the active component accounts for 1-20% of the metal-loaded catalyst by mass percent; the molar ratio of the methane to the water vapor is 1:0.1-10, the retention time of the mixed gas in the reaction zone is 0.01-100s, the high-voltage alternating current power supply is adopted for dielectric barrier discharge, the power frequency is 1kHz-50kHz, the discharge pressure is-0.06 MPa-0.2MPa, and the reaction temperature is 100-.

Further, the method is realized by adopting the following dielectric barrier discharge reactor:

the dielectric barrier discharge reactor is a linear-cylinder reactor, the reactor is cylindrical, the outside of the reactor is coated with aluminum foil, and then metal wires are wound on the outside of the aluminum foil to be used as a grounding electrode; the upper end of the cylinder is provided with an upper end enclosure with a central hole, and a metal rod is arranged along the axis of the reactor through the central hole and is used as a high-voltage electrode; the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 0.3-30 mm; the cylindrical reactor is made of a single-layer dielectric insulating material;

the upper end of the reactor is provided with methane, water vapor and argon inlets which are positioned above the discharge area, the lower end of the reactor is connected with a collector, the collector is arranged in a cold trap, and the rear end of the collector is connected with a tail gas outlet; the catalyst is arranged in a discharge area in the reactor, and a catalyst bed layer is supported by a quartz sand plate; and a heating furnace is arranged outside the discharge area and is used as a heat preservation device.

Further, the residence time of the mixed gas in the reaction zone is taken to be 0.1 to 10 s.

Further, the molar ratio of methane to water vapor is 1: 2-6.

Further, the discharge pressure was 0.1 MPa.

Further, the reaction temperature was 150-.

Further, the active component accounts for 3-10% of the catalyst by weight.

Further, the active component accounts for 3-10% of the metal-supported catalyst by weight.

Further, the distance between the outer wall of the metal rod and the inner wall of the cylindrical reactor is 1-5 mm.

Furthermore, the dielectric barrier discharge adopts a high-voltage alternating current power supply, and the power supply frequency is 12kHz-15 kHz.

Further, when dielectric barrier discharge is adopted, the high-voltage electrode and the grounding electrode are made of copper, iron, tungsten, aluminum or stainless steel.

Furthermore, the reactor is made of quartz glass, hard glass, alumina ceramic, polytetrafluoroethylene or non-metal composite materials.

The invention has the beneficial effects that: the method has mild conditions, high dispersion of the used catalyst and stable catalytic activity, belongs to a one-step direct synthesis process, and has the advantages of simple method, cheap raw materials and no pollution. Is suitable for₁-C₄The various alkanes, alkenes, alkynes and water vapor of (1) synthesize various organic compounds. In addition to methanol, products such as ethanol, acetaldehyde, acetic acid, acetone and the like can be obtained by using a plasma synthesis method.

Drawings

FIG. 1 CH₄/H₂A diagram of an experimental device for O/Ar plasma reaction.

FIG. 2 is a GC-MS analysis chart of the result of the steam methane reforming reaction product.

Detailed Description

The following detailed description of the embodiments of the invention refers to the accompanying drawings.

Comparative example 1

The reaction pressure was 0.1MPa, the external furnace was set at 200 ℃ for heat preservation, and argon, methane, and steam were fed into the discharge reactor at a molar ratio of 2:1:3 (wherein the flow rate of argon was 40ml/min, the flow rate of methane was 20ml/min, and the flow rate of steam was 60 ml/min). Firstly, reaction raw material gas is introduced to replace air in a reaction system, and simultaneously, the raw material gas is heated and premixed for 30 min. After the raw material gases are uniformly mixed, a plasma power supply is switched on to start discharging. The reactor structure is a single-medium-barrier line-barrel type reactor. The stainless steel bar installed in the quartz tube is used as an internal electrode, and the aluminum foil wound on the outer wall of the quartz tube is used as a grounding electrode. The diameter of the inner electrode is 2mm, and the discharge gap is 3.5 mm. The length of the discharge zone is 50 mm. The lowest end of the discharge area in the quartz tube is provided with a sieve plate.

The plasma discharge parameters were: power 7W, frequency 14.5 kHz. The discharge time is 2.5 h. The reaction product comprises gas phase and liquid phase, the gas phase product is directly analyzed on line through gas chromatography, and the liquid phase product is collected through a cold trap and is qualitatively and quantitatively analyzed through the gas chromatography. The reaction result is: the methane conversion was 3.4%, the liquid phase product selectivity was 62%, the methanol selectivity was 46.67%, and the by-products included ethane, ethylene, propane, formaldehyde, ethanol, propanol, acetaldehyde, acetic acid, propionaldehyde, and acetone.

Comparative example 2

Comparative example 1 was repeated with 1.4g of catalytic Silica (SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, and is calcined for 5 hours at 500 ℃ before reaction. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 4.758%, the selectivity of the liquid phase product is 31.32%, and the selectivity of methanol is 21.8799%.

Example 1:

comparative example 2 was repeated with 1.4g of silica-supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. Discharge parameter settingThe following are defined: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 7.0645%, the selectivity of the liquid phase product is 67.7349%, and the selectivity of methanol is 51.7905%.

Example 2:

comparative example 2 was repeated with 1.4g of silica supported nickel catalyst (expressed as Ni/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading amount of active ingredients calculated by element Ni is 5% (weight), and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set to 200 ℃. the discharge parameters were set to: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.9371%, the selectivity of the liquid phase product is 60.0491%, and the selectivity of methanol is 42.9067%.

Example 3:

comparative example 2 was repeated with 1.4g of silica-supported zirconium catalyst (expressed as Zr/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading amount of active ingredients is 5 percent (weight) calculated by the element Zr, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.5505%, the selectivity of the liquid phase product is 61.6109%, and the selectivity of methanol is 46.4062%.

Comparative example 3:

comparative example 2 was repeated with 1.4g of silica-supported zinc catalyst (expressed as Zn/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the element Zn is calculatedThe loading amount of the active component(s) was 5% by weight, and the catalyst calcination temperature was 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.6179%, the selectivity of the liquid phase product is 45.2417%, and the selectivity of methanol is 32.5047%.

Comparative example 4:

comparative example 2 was repeated with 1.4g of silica-supported cerium catalyst (expressed as Ce/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading amount of active ingredients calculated by element Ce is 5% (weight), and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.6425%, the selectivity of the liquid phase product is 50.3949%, and the selectivity of methanol is 32.8805%.

Comparative example 5:

comparative example 2 was repeated with 1.4g of silica supported indium catalyst (expressed as In/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element In, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.6447%, the selectivity of the liquid phase product is 49.2487%, and the selectivity of methanol is 31.9472%.

Comparative example 6:

comparative example 2 was repeated with 1.4g of silica supported molybdenum catalyst (expressed as Mo/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor is 2:1:3 (which isThe flow rate of medium argon gas is 40ml/min, the flow rate of methane is 20ml/min and the flow rate of water vapor is 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Mo, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.8052%, the selectivity of the liquid phase product is 53.6229%, and the selectivity of methanol is 31.7457%.

Comparative example 7:

comparative example 2 was repeated with 1.4g of silica supported vanadium catalyst (expressed as V/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element V, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.9199%, the selectivity of the liquid phase product is 60.9905%, and the selectivity of methanol is 18.1337%.

Comparative example 8:

comparative example 2 was repeated with 1.4g of silica supported cobalt catalyst (expressed as Co/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading amount of active ingredients calculated by element Co is 5% (weight), and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.6188%, the selectivity of the liquid phase product is 41.5620%, and the selectivity of methanol is 26.8252%.

Comparative example 9:

comparative example 2 was repeated with 1.4g of silica supported iron catalyst (denoted as F)e/SiO₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Fe, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.2315%, the selectivity of the liquid phase product is 60.9101%, and the selectivity of methanol is 39.0470%.

Comparative example 10:

comparative example 2 was repeated with 1.4g of silica supported chromium catalyst (expressed as Cr/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cr, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.6511%, the selectivity of the liquid phase product is 45.6455%, and the selectivity of methanol is 31.7853%.

Comparative example 11:

comparative example 2 was repeated with 1.4g of silica supported manganese catalyst (expressed as Mn/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Mn, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 200 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.6437%, the selectivity of liquid phase product is 49.0066%, and the selectivity of methanol is 34.8710%.

TABLE 1 evaluation results of catalytic performances of different supported metal catalysts

When the active component is Cu, the conversion rate of methane and the selectivity of methanol are the highest.

Example 4:

example 1 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 130 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 3.4212%, the selectivity of the liquid phase product is 62.2659%, and the selectivity of methanol is 46.6784%.

Example 5:

example 1 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 150 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.7758%, the selectivity of the liquid phase product is 68.0023%, and the selectivity of methanol is 50.0876%.

Example 6:

example 1 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.8823%, the selectivity of the liquid phase product is 72.9074%, and the selectivity of methanol is 55.4087%.

Example 7:

example 1 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set to 250 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 7.9023%, the selectivity of the liquid phase product is 58.3080%, and the selectivity of methanol is 44.2637%.

Example 8:

example 1 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:3 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 60 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 300 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, the product analysis can obtain that the methane conversion rate is 8.1125%, and the liquid phase product is selectedThe selectivity was 54.4213% with a selectivity to methanol of 37.7455%.

TABLE 2 Cu/SiO for different external heating temperatures₂Evaluation results of catalytic Properties of the catalyst

The preferred external heating temperature is 170 ℃.

Example 9:

example 6 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:1 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 20 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 8.3874%, the selectivity of the liquid phase product is 48.0491%, and the selectivity of methanol is 27.5474%.

Example 10:

example 6 was repeated with 1.5g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:2 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 40 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 7.9067%, the selectivity of the liquid phase product is 68.5687%, and the selectivity of methanol is 46.7642%.

Example 11:

example 6 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:4 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 80 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.3975%, the selectivity of the liquid phase product is 75.2453%, and the selectivity of methanol is 58.7456%.

Example 12:

example 6 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to steam was 2:1:5 (where the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the steam flow rate was 100 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 4.8026%, the selectivity of the liquid phase product is 65.5188%, and the selectivity of methanol is 50.7685%.

Example 13:

example 6 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:6 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 120 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis of the product can obtain that the conversion rate of methane is 3.0401%, the selectivity of the liquid phase product is 61.5096%, and the selectivity of methanol is 48.8805%.

Example 14:

example 4 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:7 (with an argon flow rate of 40ml/min, a methane flow rate of 20ml/min and a water vapor flow rate of 140 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 5 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 3.3680%, the selectivity of the liquid phase product is 50.9281%, and the selectivity of methanol is 42.5177%.

TABLE 3 Cu/SiO for different methane-to-water ratios₂Evaluation results of catalytic Properties of the catalyst

Preferably the methane to steam ratio is 1: 4.

Example 15:

example 11 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:4 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 80 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 1 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.7289%, the selectivity of the liquid phase product is 49.9668%, and the selectivity of methanol is 35.3669%.

Example 16:

example 11 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. Argon, methane and water vapor millThe molar ratio was 2:1:4 (with an argon flow rate of 40ml/min, a methane flow rate of 20ml/min and a water vapour flow rate of 80 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 3 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 5.8084%, the selectivity of the liquid phase product is 64.0302%, and the selectivity of methanol is 46.5517%.

Example 17:

example 11 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:4 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 80 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 7 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.2993%, the selectivity of the liquid phase product is 69.4974%, and the selectivity of methanol is 53.6275%.

Example 18:

example 11 was repeated with 1.4g of silica supported copper catalyst (expressed as Cu/SiO)₂) Is filled in a discharge area of the dielectric barrier discharge plasma reactor. The molar ratio of argon to methane to water vapor was 2:1:4 (wherein the argon flow rate was 40ml/min, the methane flow rate was 20ml/min, and the water vapor flow rate was 80 ml/min). The catalyst is 20-40 mesh particles, wherein the loading of active ingredients is 10 percent (weight) calculated by element Cu, and the roasting temperature of the catalyst is 540 ℃. The external furnace temperature was set at 170 ℃. The discharge parameters were set as: power 7W, frequency 14.5 kHz. After discharging for 2.5h, analysis on the product can obtain that the conversion rate of methane is 6.3975%, the selectivity of the liquid phase product is 75.2453%, and the selectivity of methanol is 58.7456%.

TABLE 4 Cu/SiO in different copper loadings (by weight)₂Evaluation results of catalytic Properties of the catalyst

The preferred Cu loading is 5 wt%.