CN116514062A - Joule thermal coupling catalysis natural gas and CO 2 Method for preparing synthetic gas by reforming dry gas - Google Patents

Abstract

The invention discloses a method for reforming synthetic gas by coupling catalytic natural gas and _CO2 dry gas with Joule heat. The process is coupled with Joule heating to achieve efficient co-conversion of methane and carbon dioxide to generate a mixture of CO and H ₂ , that is, synthesis gas. The invention realizes methane conversion rate of 90-98%; carbon dioxide conversion rate of 90-98%; carbon monoxide selectivity >99%; H ₂ /CO = 0.5-2 adjustable; carbon deposition is low. The invention has the characteristics of electrothermal conversion efficiency >90%, low electric power, long catalyst life, high methane conversion rate and product selectivity, low carbon deposition, low industrialization difficulty, good process repeatability, safe and reliable operation, etc., and has broad industrial application Application prospect.

Description

A method for preparing synthesis gas by joule heat coupled catalytic reforming of natural gas and CO2 dry gas

Technical Field

The present invention belongs to the technical field of catalytic reforming of methane and carbon dioxide to produce synthesis gas, and specifically relates to a method for preparing synthesis gas by catalytic reforming of natural gas and _CO2 dry gas through Joule heat coupling. The process realizes efficient one-step conversion of natural gas and _CO2 , and has the characteristics of high electrothermal conversion efficiency, excellent catalyst stability and less carbon deposition.

Background Art

Catalytic methane and carbon dioxide reforming (DRM) to produce synthesis gas (CO and H ₂ ) is considered to be the best reaction path. This path can greatly improve the conversion efficiency of methane, and the obtained synthesis gas H ₂ /CO≈1, which is of great industrial value, can be directly used as a feedstock gas for liquid fuel, light olefins, methanol, dimethyl ether and other oxygen-containing synthesis, and can be easily integrated with related technologies of coal chemical industry, with huge economic and environmental benefits.

As early as 1888, the DRM reaction has attracted the attention of researchers. In 1928, Fischer and Tropsch conducted a systematic study on the performance and carbon deposition behavior of the DRM reaction on Ni-based and Co-based catalysts. However, in the following decades, the reaction did not receive enough attention and there were few related studies. It was not until 1991 that Ashcroft et al. reported in Nature that the reaction could produce synthesis gas with a lower _H2 /CO ratio, and more and more researchers refocused their attention on the reaction. In the past few decades, there has been great progress in the research and development of DRM reaction catalysts and the understanding of related scientific issues.

The methane dry gas reforming catalysts reported in the research are mainly precious metal and transition metal catalysts, among which nickel-based catalysts are widely concerned due to their excellent performance, abundant reserves, and low cost and availability. They are the most promising methane dry gas reforming catalysts. However, particle sintering and carbon deposition are serious problems faced by nickel-based catalysts, which can easily lead to catalyst deactivation and reactor blockage. For example, a carrier with a large specific surface area and a well-developed pore structure is used to increase the dispersion and anchoring of nickel; through a limited domain strategy, the stability of nickel particles is increased by coating nickel particles, and the ability of catalytic activation of CO ₂ is improved by adding additives, and carbon deposition is reduced by promoting the carbon removal process (CN 104841442 A, CN 105688916 A). However, there are still problems such as complex catalyst preparation process, poor anti-carbon deposition effect, and difficulty in taking into account high activity and anti-carbon deposition performance. Therefore, designing and constructing high-temperature sintering-resistant Ni-based catalysts has become one of the most active research directions in the field of international catalysis and materials. Exploring and developing new anti-sintering strategies and developing universal anti-sintering theories have important theoretical and practical significance for catalyst design.

However, there is no report on the successful industrialization of methane dry reforming technology at home and abroad. The main reason is that the catalyst used in the reaction is prone to carbon deposition and sintering, which greatly limits the long-term operation of the catalyst. How to effectively solve or overcome the problem of catalyst carbon deposition and sintering is the key to the industrialization of this process. DRM is a strong endothermic reaction with an endothermic heat of up to 247kJ/mol. At the same time, thermodynamic calculations show (as shown in Figure 1, Chen, et al, Applied Catalysis B: Environmental, 2013, 136-137, 260) that when the temperature reaches above 900°C, carbon deposition is thermodynamically unfavorable, which means that catalyst carbon deposition can be avoided above 900°C. Most of the catalysts reported so far are oxides (such as silicon oxide, aluminum oxide, magnesium oxide, etc.) supported on metal active components (such as Ni, Ru, etc.) to react in a fixed bed. These supported catalysts have poor thermal conductivity. Using traditional electric furnaces or combustion furnaces to provide heat through thermal radiation or convection (Figure 2), the temperature near the reactor wall is higher, while the temperature in the center away from the wall is very low, with a temperature difference of 50-100°C. At the same time, due to the strong endothermic reaction, the uneven temperature of the catalyst bed is further aggravated, resulting in a large amount of carbon deposition on the catalyst in the reaction center, which seriously restricts the engineering of the DRM process.

Patent CN2022101197030 discloses a method for producing synthesis gas by thermal plasma-coupled catalytic reforming of natural gas and _CO2 dry gas, which solves the problems of process heating and uneven catalyst bed temperature by plasma-coupled metal catalytic reactor. However, the temperature in the high-temperature plasma torch is as high as 3000°C. When the working gas carries heat (its temperature is as high as 2500°C or more) and mixes with the raw gas methane and carbon dioxide, it is difficult to avoid high-temperature thermal cracking and carbon deposition of methane, which seriously reduces the carbon atom utilization rate of the process.

Summary of the invention

In order to solve the above problems, the present invention provides a method for preparing synthesis gas by Joule heat coupled catalytic conversion of _CH4 and _CO2 dry gas reforming, which effectively avoids carbon deposition due to high-temperature thermal cracking of methane, realizes the co-catalytic conversion of two greenhouse gases, methane and carbon dioxide, and simultaneously produces high-quality synthesis gas.

In order to achieve the above object, the technical solution of the present invention is specifically as follows:

A method for preparing synthesis gas by Joule heat-coupled catalytic reforming of natural gas and _CO2 dry gas, wherein a DC and/or AC power source is connected to both ends of a metal catalytic reactor and the resistance heating of the metal reactor is utilized to achieve Joule heat heating; the raw gas natural gas and _CO2 mixed gas heated by Joule heat are introduced into the metal catalytic reactor for dry gas reforming reaction to prepare synthesis gas; the power of the Joule heat is 100w-100KW, the current range is 5-10000A, and the voltage range is 1-1000V.

Preferably, the metal catalytic reactor comprises an active component and a metal tube, the catalyst active component is coated and doped on the contact surface between the metal tube and the reaction raw materials, a thin layer of catalytic dopant is formed on the contact surface between the metal tube and the reaction raw materials, the catalyst active component forms a catalyst with the base metal of the contact surface of the metal tube, and the contact surface refers to the inner wall and/or outer wall of the metal tube.

Preferably, the thickness of the catalytic dopant thin layer is 100 nm-1 mm, more preferably 200 nm-0.5 mm, more preferably 500 nm-200 μm, most preferably 1-50 μm.

Preferably, the doping is lattice doping, and the so-called lattice doping refers to the formation of chemical bonds between the doped metal elements and certain elements in the matrix metal material, so that the doped metal elements are confined in the lattice of the doped matrix, thereby producing specific catalytic properties; the catalyst active component is a metal element, or a mixture of metal elements and non-metallic elements. Based on the total weight of the dopant thin layer as 100%, the doping amount of the metal element is 0.1-20wt.%, further preferably 0.1-15wt.%, and more preferably 0.1-5wt.%.

Preferably, the metal element exists in the form of one or more of oxides, carbides, nitrides, silicides, and alloys; the metal element includes: one or more of magnesium, aluminum, calcium, barium, titanium, manganese, vanadium, niobium, tungsten, molybdenum, chromium, iron, cobalt, nickel, copper, zinc, tin, gallium, zirconium, lanthanum, cerium, ruthenium, gold, palladium, or platinum; more preferably, one or more of aluminum, barium, titanium, manganese, vanadium, niobium, tungsten, molybdenum, chromium, iron, cobalt, nickel, copper, zinc, gallium, gold, lanthanum, cerium, ruthenium, gold, palladium, or platinum.

Preferably, in the metal catalytic reactor, the material of the matrix tube includes: GH1015, GH1040, GH1131, GH1140, GH2018, GH2036, GH2038, GH2130, GH2132, GH2135, GH2136, GH2302, GH2696, GH3030, GH3039, GH3044, GH3028, GH3128, GH3536, GH605, GH600, GH4033, GH4037, GH4043, GH4049, GH4133, GH4133B, GH4169, GH4145, Hastelloy G-30, Hastelloy G-35, HastelloyN, Hastelloy S, Inconel 600, Inconel 601, Inconel Inconel Conel 754, Inconel 758, Incoloy 783, Incoloy DS, Incoloy 800, Incoloy 800H, Incoloy 802, Incoloy 803, Incoloy 804, Incoloy 825, Incoloy903, Incoloy 907, Incoloy 909, Incoloy 925, Incoloy MA956, Incoloy A-286, Incoloy25-6Mo, Monel 400, one or a combination of two or more.

Preferably, the coating method of the catalyst active component is one or more of electroplating, chemical plating, electrochemical deposition, conversion deposition precipitation, chemical vapor deposition (CVD), and physical vapor deposition (PVD).

The purpose of the following preparation process is to improve the dispersion, deposition and doping of metal elements on the surface of the metal matrix tube.

Preferably, the electrochemical deposition method comprises the following steps:

(1) The base tube is boiled in a 10-20wt.% NaOH or KOH solution for 1-2h to remove oil, rinsed clean, dried at room temperature and then used for later use;

(2) heating the substrate tube treated in step (1) in a hot _N2 atmosphere at a temperature of 300-500°C for a time of 1-2 hours to form an anti-corrosion conductive film layer;

(3) at room temperature, prepare an aqueous solution or organic solution of a doped metal element precursor, adjust the pH value of the solution to 3.3-6.5, immerse the metal pipe to be doped in the precursor solution, connect the power supply, and use platinum as the cathode, and use platinum as the anode. After connecting the circuit, adjust the distance between the cathode and the anode to 2-5 cm, adjust the DC regulated power supply, maintain the constant current mode, and the current is 5 mA-0.5 A. After electroplating for 0.5-2 hours, wash with deionized water and dry. After the deposition is completed, the metal reactor is obtained;

The doped metal element precursor used in the electrochemical deposition method is one or more of metal nitrates, soluble halides, soluble sulfates, soluble carbonates, soluble phosphates, soluble C methoxides, soluble ethoxides, soluble formates, and soluble acetates.

Preferably, the conversion sedimentation precipitation method comprises the following steps:

(1) The base tube is boiled in a 10-20wt.% NaOH or KOH solution for 1-2h to remove oil, rinsed clean, dried at room temperature and then used for later use;

(2) heating the substrate tube treated in step (1) in a hot _N2 atmosphere at a temperature of 300-500°C for a time of 1-2 hours to form an anti-corrosion conductive film layer;

(3) at room temperature, preparing an aqueous solution or organic solution of a doped metal element precursor, adjusting the pH value of the solution to 3.8-7.2, immersing the metal tube to be doped in the precursor solution, allowing the solution to flow inside the metal tube to be deposited, and then adding 10-20wt% _{H2O2 solution} for conversion deposition precipitation, the deposition time is 0.5-5h, and after the deposition is completed, the metal reactor is obtained;

The doped metal element precursor used in the conversion deposition precipitation method is one or more of metal chlorides, methoxides, ethoxides, formates and acetates.

Preferably, the reaction process also includes a pre-activation step: before the raw gas is introduced into the reaction, the metal catalytic reactor is activated to improve the catalytic activity and stability; the pre-activation conditions are: activation temperature 800-1100°C, more preferably 900-1000°C; activation pressure 0.05-1MPa, more preferably 0.1-1MPa; activation gas is one or more of argon, nitrogen, air, or oxygen; the flow rate of activation gas is 1-200L/min.

Preferably, the raw gas includes methane and carbon dioxide gas, or a mixture of methane, carbon dioxide and other gases; the other gases include one or two of inert atmosphere gas and non-inert atmosphere gas; the inert atmosphere gas is one or more of nitrogen, helium, neon, argon and krypton, and the volume content of the inert atmosphere gas in the raw gas is 0-95%; the non-inert atmosphere gas is a mixture of one or more of carbon monoxide, hydrogen and alkanes with a C number of 2-4, and the volume content ratio of the non-inert atmosphere gas to methane is 0-10%; the total volume content of methane and carbon dioxide in the raw gas is 5-100%; the volume content ratio of carbon dioxide to methane is 0.3-3, and more preferably 0.5-2.

Preferably, the reaction process is a continuous flow reaction mode, in which the reaction pressure is 0.05-1 MPa, more preferably 0.1-0.5 MPa, and the raw material gas flow rate is 1-100 L/min.

The beneficial effects of the present invention are:

1. The present invention provides a method for preparing synthesis gas by catalytic reforming of natural gas and _CO2 dry gas using Joule heat for heating, which has the following advantages: Joule heat directly acts on the gas, heating efficiency is >90%, start-stop response is fast, millisecond-level mixing is achieved, and an efficient heating system is improved for the dry reforming reaction of a strongly endothermic reaction, thereby achieving co-conversion of methane and carbon dioxide to generate high-value-added synthesis gas.

2. The present invention dopes active metal components into a nickel-chromium special alloy with a unique shape to make an integrated catalytic reactor, so that the catalyst and the reactor become one. This method has the following advantages:

(1) The integrated metal alloy catalytic reactor has the characteristics of simpler doping process, milder conditions, and more uniform dispersion of metal active components compared with quartz and silicon carbide;

(2) Compared with traditional particle catalysts, the reaction process avoids axial or radial temperature differences in the catalyst. This is because when the catalyst is filled in the reactor, the catalyst itself has poor thermal conductivity, which leads to an increase in the radial temperature difference of the bed (the temperature gradually decreases from the reactor wall to the center). Therefore, in order to make the catalyst in the center reach the reaction temperature, more heat needs to be supplied, resulting in heat loss and more side reactions near the wall (high temperature end).

(3) Compared with particle catalysts, there is no catalyst bed and no bed pressure drop, so the reaction process is smoother.

(4) Compared with particulate catalysts, the problem of scale-up is overcome.

3. The methane conversion rate of the present invention is 90-98%; the carbon dioxide conversion rate is 90-98%; the CO selectivity is >99%; CO/H ₂ = 0.5-2 adjustable; low carbon deposition.

This method has the characteristics of high electrothermal conversion efficiency (>90%), long catalyst life, high methane and carbon dioxide conversion rate, low carbon deposition, easy separation of products, no need for catalyst amplification, low industrial difficulty, good process repeatability, safe and reliable operation, etc., and has broad industrial application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a graph showing the equilibrium constants of reaction equations (1)-(4) in the DRM reaction system as a function of temperature;

Figure 2 shows the heating and temperature distribution of a conventional electric furnace and a combustion furnace;

FIG. 3 shows the Joule heat supply and temperature distribution of the present invention.

DETAILED DESCRIPTION

However, the following examples are only for explaining the present invention, and the protection scope of the present invention shall include the entire contents of the claims, not just the present examples. In addition, the concentrations of the NaOH solution, the metal precursor solution and _{the H2O2} solution described in the following examples and comparative examples are all mass percentage concentrations.

1. Preparation of catalytic reactor

Comparative Example 1

Inconel 601 alloy pipe (inner diameter 4mm outer diameter 6mm, id4od6) was selected and boiled in 15% NaOH solution for 1 hour for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min of _N2 atmosphere for 2 hours; then treated at 500℃ in high-purity hydrogen atmosphere for 2.5 hours to obtain blank 601 Metal Catalytic Reactor.

Example 1

Electrochemical deposition

GH3030 alloy tube (inner diameter 4mm outer diameter 6mm, id4od6) was selected, boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of 10% _RuCl3 aqueous solution was prepared, 20ml of 0.1mol/L citric acid was added, and the pH was adjusted to 4.5 with hydrochloric acid, a 0.5mm platinum wire was connected as the anode, and the GH3030 alloy tube was connected as the cathode, and a power supply was connected, with the distance between the platinum wire and the alloy tube being 2cm; a constant current mode was adopted, the current was set to 20mA, and after deposition for 0.5h, a Ru-deposited GH3030 alloy tube was obtained; then, it was treated at a temperature of 500℃ for 2h in a high-purity hydrogen atmosphere, a 100nm thick Ru dopant thin layer was formed on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amount of Ru is 0.5 wt.%.

Example 2

Electrochemical deposition

GH3030 alloy tube (inner diameter 12mm outer diameter 16mm, id12od16) was selected, boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of mixed aqueous solution of 10% _RuCl3 and 15% _FeCl3 was prepared, 30ml of 0.1mol/L citric acid was added, and the pH was adjusted to 4.5 with hydrochloric acid, a 0.5mm platinum wire was connected as the anode, and the GH3030 alloy tube was connected as the cathode, and a power supply was connected, with the distance between the platinum wire and the alloy tube being 2cm; a constant current mode was adopted, the current was set to 25mA, and after deposition for 0.5h, a GH3030 alloy tube with Ru and Fe deposition was obtained; then, it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2h, and a thin layer of Ru and Fe dopants with a thickness of 110nm was formed on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amounts of Ru and Fe are 0.8wt.% and 1wt.% respectively.

Example 3

Electrochemical deposition

Inconel 601 alloy pipes (10 mm inner diameter and 14 mm outer diameter, id10od14) were selected and boiled in 15% NaOH solution for 1 h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300 °C and 200 ml/min of N ₂ atmosphere for 2 h; 2L of a mixed aqueous solution of 20% Co(NO ₃ ) ₂ and 15% FeCl ₃ was prepared, 20 ml of 0.1 mol/L citric acid was added, and the pH was adjusted to 3.8 with hydrochloric acid, and a 0.5 mm platinum wire was connected as an anode, and the Inconel The 601 alloy tube was used as the cathode and connected to a power source. The distance between the platinum wire and the alloy tube was 2 cm. The constant current mode was adopted and the current was set to 25 mA. After deposition for 1 hour, the Inconel 601 alloy tube with Co and Fe deposition was obtained. Subsequently, it was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2.5 hours to form a 110 nm thick Co and Fe dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 601 metal catalytic reactor, wherein the doping amounts of Co and Fe are 1.5wt.% and 0.6wt.% respectively.

Example 4

Electrochemical deposition

Inconel 601 alloy pipes (inner diameter 10mm outer diameter 14mm, id10od14) were selected and boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of a mixed aqueous solution of 20% Ni( _NO3 ) ₂ and 15% Co( _NO3 ) ₂ was prepared, 19ml of 0.1mol/L citric acid was added, and the pH was adjusted to 3.8 with nitric acid, a 0.5mm platinum wire was connected as the anode, the Inconel 601 alloy pipe was connected as the cathode, and a power supply was connected, with the distance between the platinum wire and the alloy pipe being 2cm. The constant current mode was used, and the current was set to 30 mA. After 1 hour of deposition, the Inconel601 alloy tube with Co and Ni deposition was obtained. Subsequently, it was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2.5 hours to form a 110nm thick Co and Ni dopant layer on the contact surface of the reactor, and then naturally cooled to obtain 601 metal catalytic reactor, wherein the doping amounts of Ni and Co are 1.5wt.% and 1.1wt.% respectively.

Example 5

Electrochemical deposition

Inconel 600 alloy pipe (inner diameter 16mm outer diameter 20mm, id16od20) was selected, boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of mixed aqueous solution of 10% _RuCl3 and 15% Cu( _NO3 ) ₂ was prepared, 32ml of 0.1mol/L citric acid and nitric acid were added to adjust the pH to 4.1, 0.5mm platinum wire was connected as anode, Inconel 600 alloy pipe was connected as cathode, power was connected, and the distance between platinum wire and alloy pipe was 2cm; constant current mode was adopted, current was set to 25mA, and after deposition for 1h, Inconel with Ru and Cu deposition was obtained. 600 alloy tube; then treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours, forming a 120nm thick Ru and Cu dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 600 metal catalytic reactor, wherein the doping amounts of Ru and Cu are 0.5wt.% and 0.6wt.% respectively.

Example 6

Electrochemical deposition

Incoloy 800 alloy pipes (15 mm inner diameter, 20 mm outer diameter, id15od20) were selected and boiled in 15% NaOH solution for 1 h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300 °C and 200 ml/min of N ₂ atmosphere for 2 h; 2L of a mixed aqueous solution of 20% Ni(NO ₃ ) ₂ and 15% Co(NO ₃ ) ₂ was prepared, 36 ml of 0.1 mol/L citric acid was added, and the pH was adjusted to 4.3 with nitric acid, a 0.5 mm platinum wire was connected as an anode, and Incoloy The 800 alloy tube was used as the cathode and connected to a power source. The distance between the platinum wire and the alloy tube was 1 cm. The constant current mode was adopted and the current was set to 80 mA. After 1 hour of deposition, the Incoloy 800 alloy tube with Ni and Co deposition was obtained. Subsequently, it was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a 150nm thick Ni and Co dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 800 metal catalytic reactor, wherein the doping amounts of Ni and Co are 2wt.% and 1.2wt.% respectively.

Example 7

Electrochemical deposition

Monel 400 alloy pipe (inner diameter 15mm outer diameter 20mm, id15od20) was selected, boiled in 15% NaOH solution for 1 hour for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 20% Ni( _NO3 ) ₂ and 15% Co( _NO3 ) ₂ was prepared, 41ml of 0.1mol/L citric acid and nitric acid were added to adjust the pH to 4.3, 0.5mm platinum wire was connected as anode, Incoloy 800 alloy pipe was connected as cathode, power was connected, and the distance between the platinum wire and the alloy pipe was 1cm; constant current mode was adopted, the current was set to 80mA, and after deposition for 1 hour, Ni and Co deposited Monel 400 alloy tube; then treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a 150nm thick Ni and Co dopant thin layer on the contact surface of the reactor, and then cooled naturally to obtain 400 metal catalytic reactor, wherein the doping amounts of Ni and Co are 2wt.% and 1.2wt.% respectively.

Example 8

Electrochemical deposition

Inconel X-750 alloy pipe (inner diameter 15mm outer diameter 20mm, id15od20) was selected, boiled in 15% NaOH solution for 1 hour for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 20% Ni( _NO3 ) ₂ and 15% Zn( _NO3 ) ₂ was prepared, 31ml of 0.1mol/L citric acid and nitric acid were added to adjust the pH to 4.3, 0.5mm platinum wire was connected as anode, Incoloy 800 alloy pipe was connected as cathode, power was connected, and the distance between platinum wire and alloy pipe was 1cm; constant current mode was adopted, current was set to 100mA, and after deposition for 1 hour, Inconel deposited with Ni and Zn was obtained. X-750 alloy tube; then treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours, a 180nm thick Ni and Zn dopant thin layer was formed on the contact surface of the reactor, and then naturally cooled to obtain X-750 metal catalytic reactor, in which the doping amounts of Ni and Zn are 2wt.% and 1.2wt.% respectively.

Example 9

Electrochemical deposition

A Hastelloy G-30 alloy tube (inner diameter 16 mm, outer diameter 20 mm, id16od20) was selected, boiled in a 15% NaOH solution for 1 hour for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300°C and a continuously flowing 200 ml/min _N2 atmosphere for 2 hours; 2L of a mixed aqueous solution of 25% Ni( _NO3 ) ₂ and 15% La( _NO3 ) ₃ was prepared, 26 ml of 0.1 mol/L citric acid and nitric acid were added to adjust the pH to 4.3, a 0.5 mm platinum wire was connected as an anode, a Hastelloy G-30 alloy tube was connected as a cathode, a power supply was connected, and the distance between the platinum wire and the alloy tube was 1 cm; a constant current mode was adopted, the current was set to 100 mA, and after deposition for 1 hour, Hastelloy with Ni and La deposited was obtained. G-30 alloy tube; then treated at 500 ° C in a high-purity hydrogen atmosphere for 2 hours, forming a 180nm thick Ni and La dopant layer on the contact surface of the reactor, and then naturally cooled to obtain G-30 metal catalytic reactor, in which the doping amounts of Ni and La are 2.5wt.% and 1.6wt.%, respectively.

Example 10

Electrochemical deposition

Inconel 600 alloy pipe (inner diameter 10mm outer diameter 14mm, id10od14) was selected, boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of mixed aqueous solution of 10% chloroauric acid and 15% La( _NO3 ) ₃ was prepared, 35ml of 0.1mol/L citric acid and nitric acid were added to adjust the pH to 4.1, 0.5mm platinum wire was connected as anode, GH2130 alloy pipe was connected as cathode, power was connected, and the distance between platinum wire and alloy pipe was 2cm; constant current mode was adopted, current was set to 30mA, and after deposition for 1h, Inconel with Au and La deposition was obtained. 600 alloy tube; then treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours, forming a 120nm thick Au and La dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 600 metal catalytic reactor, wherein the doping amounts of Au and La are 0.5wt.% and 0.8wt.% respectively.

Embodiment 11

Electrochemical deposition

GH4169 alloy pipe (12mm inner diameter, 18mm outer diameter, id12od18) was selected and boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 25% Ni( _NO3 ) ₂ , 16% Al( _NO3 ) ₃ and 15% Fe( _NO3 ) ₃ , add 30ml of 0.1mol/L citric acid, nitric acid to adjust the pH to 4.0, connect a 0.5mm platinum wire as an anode, connect a GH4169 alloy tube as a cathode, connect a power supply, and the distance between the platinum wire and the alloy tube is 2cm; adopt a constant current mode, set the current to 100mA, and after 1 hour of deposition, obtain a GH4169 alloy tube with Ni, Al and Fe deposits; then treat it in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours, form a 160nm thick Ni, Al and Fe dopant thin layer on the contact surface of the reactor, and then cool it naturally to obtain A metal catalytic reactor, wherein the doping amounts of Ni, Al and Fe are 2.5wt.%, 1.5wt.% and 1.2wt.% respectively.

Example 12

Electrochemical deposition

Incoloy 903 alloy pipes (inner diameter 14mm outer diameter 18mm, id14od18) were selected and boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of mixed aqueous solution of 25% La( _NO3 ) ₃ , 15% Ce( _NO3 ) ₃ and 15% Fe( _NO3 ) ₃ was prepared, 22ml of 0.1mol/L citric acid was added, and nitric acid was used to adjust the pH to 3.6, and a 0.5mm platinum wire was connected as the anode, and the Incoloy The 903 alloy tube was used as the cathode and connected to a power source. The distance between the platinum wire and the alloy tube was 2 cm. The constant current mode was adopted and the current was set to 200 mA. After deposition for 1 hour, the Incoloy903 alloy tube with La, Ce and Fe deposition was obtained. Subsequently, it was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a 180nm thick Ni, Al and Fe dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 903 metal catalytic reactor, in which the doping amounts of La, Ce and Fe are 3wt.%, 2.8wt.% and 1.1wt.% respectively.

Example 13

Transformation Sedimentation

Incoloy 800 alloy pipe (inner diameter 12mm outer diameter 18mm, id12od18) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of 10% Ce( _NO3 ) ₂ aqueous solution was prepared, 25ml of 0.1mol/L citric acid and 12ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1 hour, Incoloy 800 alloy pipe with Ce deposition was obtained; then it was treated in _a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a 100nm thick Ce dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain The metal catalytic reactor has a Ce doping amount of 0.8 wt.%.

Embodiment 14

Transformation Sedimentation

GH4169 alloy pipe (inner diameter 14mm outer diameter 18mm, id14od18) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 10% Ce( _NO3 ) ₂ and 20% Fe( _NO3 ) ₃ was prepared, 20ml of 0.1mol/L citric acid and 22ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1 hour, GH4169 alloy pipe with Ce deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form _a 100nm thick Ce and Fe dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amounts of Ce and Fe are 1.2wt.% and 1.1wt.% respectively.

Embodiment 15

Transformation Sedimentation

Incoloy 800 alloy pipe (inner diameter 14mm outer diameter 18mm, id14od18) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 20% La( _NO3 ) ₃ , 15% Ce( _NO3 ) ₃ and 20% Fe( _NO3 ) ₃ was prepared, 26ml of 0.1mol/L citric acid and _22ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1.5 hours, Incoloy 800 alloy pipe with La, Ce and Fe deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a thin layer of La, Ce and Fe dopants with a thickness of 100nm on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amounts of La, Ce and Fe are 1.6wt.%, 1.0wt.% and 1.1wt.% respectively.

Example 16

Transformation Sedimentation

Inconel 725 alloy pipe (inner diameter 14mm outer diameter 18mm, id14od18) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 20% Al( _NO3 ) ₃ , 15% Ce( _NO3 ) ₃ and 20% Fe( _NO3 ) ₃ was prepared, 26ml of 0.1mol/L citric acid and _22ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1.5 hours, Inconel 725 alloy pipe with La, Ce and Fe deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a thin layer of Al, Ce and Fe dopants with a thickness of 140nm on the contact surface of the reactor, and then naturally cooled to obtain 725 metal catalytic reactor, wherein the doping amounts of Al, Ce and Fe are 1.4wt.%, 1.1wt.% and 1.4wt.% respectively.

Embodiment 17

Transformation Sedimentation

Inconel 718 alloy pipe (inner diameter 21mm outer diameter 25mm, id21od25) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of mixed aqueous solution of 20% Ni( _NO3 ) ₂ and 15% Zn( _NO3 ) ₂ was prepared, 30ml of 0.1mol/L citric acid and _50ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1.5 hours, Inconel 718 alloy pipe with Ni and Zn deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a 130nm thick Ni and Zn dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain 718 metal catalytic reactor, wherein the doping amounts of Ni and Zn are 4.5wt.% and 1.0wt.% respectively.

Embodiment 18

Transformation Sedimentation

Inconel 600 alloy pipe (inner diameter 10mm outer diameter 14mm, id10od14) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then treated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of aqueous solution of 20% La( _NO3 ) ₃ , 15% Ce( _NO3 ) ₃ and 20% Fe( _NO3 ) ₃ was prepared, 26ml of 0.1mol/L citric acid and 22ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1.5 hours, Inconel 600 alloy pipe with La, Ce and _Fe deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a thin layer of La, Ce and Fe dopants with a thickness of 100nm on the contact surface of the reactor, and then naturally cooled to obtain 600 metal catalytic reactor, wherein the doping amounts of La, Ce and Fe are 1.6wt.%, 1.0wt.% and 1.1wt.% respectively.

Embodiment 19

Transformation Sedimentation

GH600 alloy pipe (inner diameter 10mm outer diameter 14mm, id10od14) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then heated at 300℃ and 200ml/min _N2 atmosphere for 2 hours; 2L of 20% Ni( _NO3 ) ₂ and 15% Ce( _NO3 ) ₃ aqueous solution was prepared, 100ml of 0.1mol/L citric acid and 40ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 2 hours, GH600 alloy pipe with Ni and Ce deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500℃ for 2 hours to form a 100nm thick _Ni and Ce dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amounts of Ni and Ce are 8.5wt.% and 2.0wt.% respectively.

Embodiment 20

Transformation Sedimentation

A Hastelloy G-35 alloy tube (10 mm inner diameter and 14 mm outer diameter, id10od14) was selected, boiled in a 15% NaOH solution for 1 hour for deoiling, rinsed with distilled water, dried at room temperature, and then heated at 300°C and a 200 ml/min _N2 atmosphere for 2 hours; 2L of an aqueous solution of 20% Ni( _NO3 ) ₂ and 25% Fe( _NO3 ) ₃ was prepared, 100 ml of 0.1 mol/L citric acid and 35 ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 3 hours, a Hastelloy G- ₃₅ alloy tube with Ni and Fe deposited was obtained; then, the tube was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a 130 nm thick Ni and Fe dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain a Hastelloy G-35 alloy tube. G-35 metal catalytic reactor, in which the doping amounts of Ni and Fe are 8.5wt.% and 7.8wt.%, respectively.

Embodiment 21

Transformation Sedimentation

A Monel 400 alloy pipe (inner diameter 12 mm outer diameter 16 mm, id12od16) was selected, boiled in a 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then heated at 300°C and a _N2 atmosphere with a continuous flow of 200 ml/min for 2 hours; 2L of an aqueous solution of 20% Ba( _NO3 ) ₂ and 15% Fe( _NO3 ) ₃ was prepared, 33ml of 0.1mol/L citric acid and 40ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 1.5 hours, a Monel 400 alloy pipe with Ba and Fe deposited was obtained; then, it was treated in _a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a thin layer of Ba and Fe dopants with a thickness of 120nm on the contact surface of the reactor, and then naturally cooled to obtain 400 metal catalytic reactor, wherein the doping amounts of Ba and Fe are 2.2wt.% and 3wt.% respectively.

Example 22

Transformation Sedimentation

GH1015 alloy pipe (10 mm inner diameter and 14 mm outer diameter, id10od14) was selected, boiled in 15% NaOH solution for 1 hour for deoiling treatment, rinsed with distilled water, dried at room temperature, and then heated at 300°C and 200 ml/min _N2 atmosphere for 2 hours; 2L of 15% Ni( _NO3 ) ₂ and 25% Mg( _NO3 ) ₂ aqueous solution was prepared, 45 ml of 0.1 mol/L citric acid and 45 ml of 10% _H2O2 were added; after the aqueous solution was circulated and deposited for 3 hours, a _GH1015 alloy pipe with Ni and Mg deposition was obtained; then it was treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours to form a 120 nm thick Ni and Mg dopant thin layer on the contact surface of the reactor, and then naturally cooled to obtain A metal catalytic reactor, wherein the doping amounts of Ni and Mg are 5.2wt.% and 4.6wt.%, respectively.

Embodiment 23

Transformation Sedimentation

Inconel 783 alloy pipe (inner diameter 12mm outer diameter 16mm, id12od16) was selected, boiled in 15% NaOH solution for 1h for deoiling, rinsed with distilled water, dried at room temperature, and then heated at 300℃ and 200ml/min _N2 atmosphere for 2h; 2L of aqueous solution of 20% Ni( _NO3 ) ₂ , 10% Mn( _NO3 ) ₂ , 15% Fe( _NO3 ) ₃ and 10% Zn(NO3)2 was prepared, 40ml of 0.1mol/L citric acid and 50ml of 10% _H2O2 were added; after 3h of cyclic deposition of aqueous solution, Inconel with Ni, Mn, Fe and Zn deposition was obtained _. 783 alloy tube; then treated in a high-purity hydrogen atmosphere at a temperature of 500°C for 2 hours, a 160nm thick Ni, Mn, Fe and Zn dopant thin layer was formed on the contact surface of the reactor, and then naturally cooled to obtain 783 metal catalytic reactor, wherein the doping amounts of Ni, Mn, Fe and Zn are 5wt.%, 2.5wt.%, 3wt.%, and 1.5wt.%, respectively.

2. Direct catalytic reforming of methane and carbon dioxide dry gas into synthesis gas under continuous flow conditions

All the catalytic reactors described above can be used directly without loading the catalyst.

All reaction examples were carried out in a continuous flow microreactor equipped with a gas mass flowmeter, a gas deoxygenation and dehydration tube, and an online product analysis chromatograph (the tail gas of the reactor was directly connected to the quantitative valve of the chromatograph for periodic real-time sampling and analysis).

Unless otherwise specified, the raw material mixed gas is 40% CH ₄ /40% CO ₂ /20% N ₂ by volume, with N ₂ as the internal standard gas. The online product analysis uses an Agilent 7890B gas chromatograph equipped with FID and TCD dual detectors, where the FID detector is equipped with an HP-1 capillary column to analyze light olefins, light alkanes and aromatics; the TCD detector is equipped with a HayesepD packed column to analyze light olefins, light alkanes, methane, hydrogen and internal standard nitrogen. The methane conversion rate, product selectivity and carbon deposition are calculated based on the carbon balance before and after the reaction, and the formula is as follows:

Methane conversion rate,

CO ₂ conversion rate,

in, The peak areas of methane and carbon dioxide at the outlet of the exhaust gas after the reaction on the detector; The nitrogen peak area at the tail gas outlet after the reaction on the TCD detector; The peak areas of methane and carbon dioxide at room temperature on the TCD detector; Methane peak area at room temperature on the TCD detector.

The selectivity of CO,

in, The total number of carbon atoms entering the reactor; The total number of carbon atoms in the methane entering the reactor; The total number of carbon atoms in the methane entering the reactor; Relative correction factors for methane and nitrogen on the TCD detector; The relative correction factor of ethane and nitrogen on the TCD detector; Sel. _CO is the selectivity of CO product;

The products in the following examples are all products that can be detected by gas chromatography.

Application Comparative Example 1

The 1.6-meter blank without metal active component doped prepared in Comparative Example 1 was used. 5 g of 20-40 mesh 1.5wt.% Ni-1.1wt.% Co/SiO ₂ powder catalyst was added to a 601 metal reactor. After the air in the reactor was replaced by 0.5 L/min Ar gas for about 30 minutes, the plasma parameters were adjusted as follows: the power was 0.5 kW, the Ar flow rate was kept constant, the temperature was programmed to 900°C from room temperature at a heating rate of 6°C/min, and at the same time, 40% CH ₄ /40% CO ₂ /20% N ₂ (volume content) was adjusted, the flow rate of the raw gas was 2 L/min, and online analysis was started after 30 minutes. The analysis results showed that the conversion rate of methane was 85%, the conversion rate of carbon dioxide was 87%, and CO/H ₂ =0.95.

Application Comparative Example 2

The 1.6-meter blank without metal active component doped prepared in Comparative Example 1 was used. 5 g of 20-40 mesh 1.5wt.% Ni-1.1wt.% Co/SiO ₂ powder catalyst was added to a 601 metal reactor. After coupling with Joule heat, the air in the reactor was replaced by 0.5L/min Ar gas for about 30 minutes. The power supply parameters were adjusted to: current 88A, DC voltage 5V, power 0.44kW, and the Ar flow rate was kept unchanged. At the same time, 40% CH ₄ /40% CO ₂ /20% N ₂ (volume content) was adjusted, and the flow rate of the raw gas was 2L/min. After 200 hours of stability test, carbon deposition caused the reactor to be blocked and the reaction stopped. The analysis results showed that the conversion rate of methane was 54-86%, the conversion rate of carbon dioxide was 63-88%, and CO/H ₂ =0.9.

Application Comparative Example 3

Using the prepared A 601 metal catalytic reactor was heated from outside a heating furnace (the power of the heating furnace was 6.5 kW). After the air in the reactor was replaced with 0.5 L/min Ar gas for about 30 minutes, the Ar protective gas was maintained for 30 minutes before online analysis was started. After the air in the reactor was replaced for about 30 minutes, the Ar flow rate was maintained unchanged, and the temperature was programmed to 900°C from room temperature at a heating rate of 6°C/min. At the same time, 40% _CH4 /40% _CO2 /20% _N2 (volume content) was adjusted. The analysis results showed that the conversion rate of methane was 86%, the conversion rate of carbon dioxide was 87%, the CO selectivity was 98%, and CO/ _H2 = 0.88.

Application Comparative Example 4

The 1.6-meter blank without metal active component doped prepared in Comparative Example 1 was used. 601 metal reactor, after replacing the air in the reactor with 0.5L/min Ar gas for about 30 minutes, keep the Ar flow rate unchanged, and program the temperature from room temperature to 900°C at a heating rate of 6°C/min, while adjusting 40% _CH4 /40% _CO2 /20% _N2 (volume content, the flow rate of raw gas is 2L/min, keep it for 30 minutes and start online analysis. The analysis results show that the conversion rate of methane is 5%, the conversion rate of carbon dioxide is 8.5%, the CO selectivity is 96%, and CO/ _H2 =1.

Application Example 1

Using the 1.6 m After coupling Joule heat, the metal catalytic reactor was replaced with 0.5L/min Ar gas for about 30 minutes to replace the air in the reactor. The power supply parameters were adjusted to: current 90A, DC voltage 5V, power 0.45kW, and raw gas mixture 30% CO ₂ /60% CH ₄ /10% N ₂ at 2L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 91%, the conversion rate of carbon dioxide was 91%, the CO selectivity was 100%, and CO/H ₂ =0.5.

Application Example 2

Using the 1.6 m After coupling Joule heat, the metal catalytic reactor was replaced with 0.5L/min Ar gas to replace the air in the reactor for about 30 minutes, and then the power supply parameters were adjusted to: current 91A, DC voltage 6V, power 0.546kW, and raw gas mixture 3.0L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 92%, the conversion rate of carbon dioxide was 92%, the selectivity of CO was 99%, and CO/H ₂ =1.

Application Example 3

Using the 1.6 m After coupling Joule heat, the metal catalytic reactor was replaced with 0.5L/min Ar gas to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 88A, AC voltage 6V, power 0.528kW, and raw gas mixture 2.5L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 95%, the conversion rate of carbon dioxide was 97%, the CO selectivity was 99%, and CO/ _H2 =1.

Application Example 4

Using the 1.6 m After coupling Joule heat, the metal catalytic reactor was replaced with 0.5 L/min Ar gas to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 98 A, DC voltage 6 V, power 0.588 kW, and raw gas mixture 45% CO ₂ /30% CH ₄ /25% N ₂ at 3.0 L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 94%, the conversion rate of carbon dioxide was 94%, the CO selectivity was 99.5%, and CO/H ₂ =1.5.

Application Example 5

Using the 1.6 m In the 601 metal catalytic reactor, after coupling with Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and then the power supply parameters were adjusted to: current 100A, DC voltage 6V, power 0.6kW, and raw gas mixture 3.0L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 95%, the conversion rate of carbon dioxide was 95%, the selectivity of CO was 99.5%, and CO/H ₂ =1.

Application Example 6

Using the prepared In the 601 metal catalytic reactor, after coupling with Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 110A, DC voltage 6V, power 0.66kW, and raw gas mixture 5.0L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 94%, the conversion rate of carbon dioxide was 95%, the CO selectivity was 99%, and CO/H ₂ =1.

Compared with the comparative example 3 (using 6.5kW electric furnace external heating), the present application example uses Joule heat heating (0.66kW), and its methane and carbon dioxide conversion rates are improved, and it is more energy-efficient.

Application Example 7

Using the prepared In the 601 metal catalytic reactor, after coupling with Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 88A, DC voltage 5V, power 0.44kW, and raw gas 60% CO ₂ /30% CH ₄ /10% N ₂ mixed gas at 4.0L/min. After maintaining for 30 minutes, online analysis was started. The analysis results showed that the conversion rate of methane was 93%, the conversion rate of carbon dioxide was 93%, the selectivity of CO was 99%, and CO/H ₂ =2.

Application Examples (8-29)

Using the 1.6 m 600 metal catalytic reactor, after coupling Joule heat, use 0.5L/min Ar gas to replace the air in the reactor for about 30 minutes, adjust the power supply parameters: current, voltage and raw gas flow rate as shown in the following table, maintain for 30 minutes and then start online analysis. The analysis results are shown in the following table.

Table 1

Application Example 30

Using the 1.6 m 400 metal catalytic reactor, after coupling Joule heat, use 0.5L/min Ar gas to replace the air in the reactor for about 30 minutes, adjust the power supply parameters to: current 95A, DC voltage 7V, power 0.665kW, raw gas mixture 4.0L/min, maintain for 30 minutes and start online analysis. The analysis results show that the conversion rate of methane is 96%, the conversion rate of carbon dioxide is 98%, the CO selectivity is 99%, and CO/ _H2 =1.

Application Example 31

Using the 1.6 m After coupling Joule heat, the X-750 metal catalytic reactor used 0.5L/min Ar gas to replace the air in the reactor for about 30 minutes, and then adjusted the power supply parameters to: current 88A, DC voltage 5V, power 0.44kW, raw gas mixture 3.0L/min. After maintaining for 30 minutes, online analysis began. The analysis results showed that the methane conversion rate was 95%, the carbon dioxide conversion rate was 97%, the CO selectivity was 99%, and CO/ _H2 =1.

Application Example 32

Using the 1.6 m After coupling Joule heat, the G-30 metal catalytic reactor was used to replace the air in the reactor with 0.5L/min Ar gas for about 30 minutes, and the power supply parameters were adjusted to: current 95A, DC voltage 6V, power 0.57kW, and raw gas mixture 4.0L/min. After maintaining for 30 minutes, online analysis began. The analysis results showed that the methane conversion rate was 97%, the carbon dioxide conversion rate was 98%, the CO selectivity was 99%, and CO/ _H2 =1.

Application Examples 33-46

Using the 1.6 m After coupling Joule heat, the metal catalytic reactor was replaced with 0.5L/min Ar gas for about 30 minutes to replace the air in the reactor. The power supply parameters were adjusted as follows: current, voltage and feed gas flow rate. After 30 minutes, online analysis was started. The analysis results are shown in the following table.

Table 2

Application Example 47

Using the 1.6 m 600 metal catalytic reactor, after coupling Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 105A, AC voltage 6V, power 0.63kW, raw gas mixture 5.0L/min. After maintaining for 30 minutes, online analysis was started and a 100-hour stability test was carried out. The analysis results showed that the methane conversion rate was 97%, the carbon dioxide conversion rate was 98%, the CO selectivity was 99%, and CO/ _H2 =1.

Application Example 48

Using the 20 m 600 metal catalytic reactor, after coupling Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 150A, DC voltage 10V, power 1.5kW, raw gas mixture 16.0L/min. After maintaining for 30 minutes, online analysis was started and a 100-hour stability test was carried out. The analysis results showed that the methane conversion rate was 97%, the carbon dioxide conversion rate was 98%, the CO selectivity was 99%, and CO/ _H2 =1.

Application Example 49

Using the 1.6 m 600 metal catalytic reactor, after coupling Joule heat, 0.5L/min Ar gas was used to replace the air in the reactor for about 30 minutes, and the power supply parameters were adjusted to: current 190A, DC voltage 10V, power 1.9kW, raw gas mixture 21L/min. After maintaining for 30 minutes, online analysis was started and a 100-hour stability test was carried out. The analysis results showed that the methane conversion rate was 98%, the carbon dioxide conversion rate was 98%, the CO selectivity was 99%, and CO/H ₂ =1.

In summary, the present invention, in the Joule heat coupled catalytic reactor mode, has methane and carbon dioxide conversion rates of 90-98% respectively; CO selectivity>99%; CO/H ₂ =0.5-2 adjustable; and low carbon deposition.

It can be concluded that the catalytic reactor of the present invention has a thermoelectric conversion efficiency of >90%, the catalyst has a long life, high product selectivity, less carbon deposition, good process repeatability, safe and reliable operation, etc., and has broad industrial application prospects.

It should be noted that, according to the above-mentioned embodiments of the present invention, those skilled in the art can fully implement the full scope of the independent claims and dependent rights of the present invention, and the implementation process and method are the same as the above-mentioned embodiments; and the parts not elaborated in detail in the present invention belong to the well-known technology in the field.

The above descriptions are only some specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any person familiar with the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. Joule thermal coupling catalysis natural gas and CO ₂ The method for preparing the synthesis gas by reforming the dry gas is characterized by comprising the following steps of: by combining The direct current and/or alternating current power supply is connected with two ends of the metal catalytic reactor, and the joule heat heating is realized by using the resistance heating of the metal reactor; heating raw material gas natural gas and CO by Joule heat ₂ Introducing the mixed gas into a metal catalytic reactor to carry out dry gas reforming reaction to prepare synthesis gas; the power of the Joule heat is 100w-100KW, the current range is 5-10000A, and the voltage range is 1-1000V.

2. The method of claim 1, wherein the metal catalytic reactor comprises an active component and a metal tube, wherein the catalyst active component is coated and doped on the contact surface of the metal tube and the reaction raw material, a thin layer of catalytic dopant is formed on the contact surface of the metal tube and the reaction raw material, the catalyst active component and the contact surface of the metal tube form a catalyst with the base metal, and the contact surface refers to the inner wall and/or the outer wall of the metal tube.

3. The method according to claim 1, characterized in that: the thickness of the catalytic dopant thin layer is 100nm-1mm.

4. The method according to claim 4, wherein: the doping is lattice doping; the active component of the catalyst is metal element or a mixture of metal element and nonmetal element, and the doping amount of the metal element is 0.1-20wt.% based on 100% of the total weight of the dopant thin layer.

The existence state of the metal element is one or more of oxide, carbide, nitride, silicide and alloy; the metal element includes: one or more of magnesium, aluminum, calcium, barium, titanium, manganese, vanadium, niobium, tungsten, molybdenum, chromium, iron, cobalt, nickel, copper, zinc, tin, gallium, zirconium, lanthanum, cerium, ruthenium, gold, palladium or platinum.

5. The method according to claim 1, characterized in that: the coating mode of the catalyst active component is one or more than two of electroplating, chemical plating, electrochemical deposition, conversion deposition precipitation, chemical vapor deposition and physical vapor deposition.

6. The method according to claim 5, wherein: the electrochemical deposition method comprises the following steps:

(1) Steaming the base pipe in 10-20wt.% NaOH or KOH solution for 1-2h, deoiling, washing, and air drying at normal temperature;

(2) The matrix pipe processed in the step (1) is heated to N ₂ Heating in atmosphere at 300-500 deg.c for 1-2 hr to form anticorrosive conducting film layer;

(3) Preparing an aqueous solution or an organic solution of a precursor doped with metal elements at room temperature, preparing the pH value of the solution to 3.3-6.5, immersing a metal pipe to be doped in the precursor solution, connecting the metal pipe to be doped with the precursor solution with the pH value as a cathode and platinum as an anode, adjusting the distance between the cathode and the anode to be 2-5cm after the metal pipe is connected with the circuit, adjusting a direct-current stabilized power supply, maintaining a constant-current mode, keeping the current to be 5mA-0.5A, and washing and drying the metal pipe with deionized water after electrodeposition for 0.5-2h, and obtaining the metal reactor after deposition is completed;

The doped metal element precursor is one or more than two of metal nitrate, soluble halide, soluble sulfate, soluble carbonate, soluble phosphate, soluble C methoxide, soluble ethoxide, soluble formate and soluble acetate.

7. The method according to claim 5, wherein: the conversion deposition precipitation method comprises the following steps:

(1) Steaming the base pipe in 10-20wt.% NaOH or KOH solution for 1-2h, deoiling, washing, and air drying at normal temperature;

(2) The matrix pipe processed in the step (1) is heated to N ₂ Heating in atmosphere at 300-500 deg.c for 1-2 hr to form anticorrosive conducting film layer;

(3) Preparing an aqueous solution or an organic solution of a precursor of the doped metal element at room temperature, adjusting the pH value of the prepared solution to 3.8-7.2, and preparing the metal pipe to be dopedImmersing in the precursor solution to make the solution in a flowing state in the metal pipe to be deposited, and then adding 10-20wt% of H ₂ O ₂ Carrying out conversion deposition precipitation on the solution, wherein the deposition time is 0.5-5h, and obtaining the metal reactor after the deposition is completed;

the doped metal element precursor is one or more of chloride, methoxide, ethoxide, formate and acetate of metal.

8. The method according to claim 1, characterized in that: the reaction process further comprises a pre-activation step: before the raw material gas is introduced to react, the metal catalytic reactor is activated, and the preactivation conditions are as follows: the activation temperature is 800-1100 ℃; the activation pressure is 0.05-1MPa; the activating gas is one or more than two of argon, nitrogen, air or oxygen; the flow rate of the activating gas is 1-200L/min.

9. The method according to claim 1, characterized in that: the raw material gas comprises methane and carbon dioxide gas or mixed gas of methane, carbon dioxide and other gases; the other gas comprises one or two of inert atmosphere gas and non-inert atmosphere gas;

the inert atmosphere gas is one or more than two of nitrogen, helium, neon, argon and krypton, and the volume content of the inert atmosphere gas in the raw material gas is 0-95%;

the non-inert atmosphere gas is one or a mixture of more than two of carbon monoxide, hydrogen and alkane with the C number of 2-4, and the volume content ratio of the non-inert atmosphere gas to methane is 0-10%;

the total volume content of methane and carbon dioxide in the raw material gas is 5-100%;

The volume content ratio of the carbon dioxide to the methane is 0.3-3.

10. The method according to claim 1, characterized in that: the reaction process is a continuous flow reaction mode, the reaction pressure is 0.05-1MPa, and the flow rate of raw material gas is 1-100L/min.