Process and apparatus for catalytic cracking of methane

Abstract

The application relates to the field of hydrogen production from methane, and specifically discloses a new process for methane catalytic cracking, which comprises the following steps: a reduction reaction, wherein methane is introduced into an oxygen carrier to perform the reduction reaction, the reaction temperature is controlled to be 500-700 DEG C, the reduction is performed under normal pressure for 2-4 hours, and generated gas I and a metal with catalytic activity are obtained; a catalytic cracking reaction, wherein when hydrogen is generated, the generated gas I and the reduced oxygen carrier are separated, then methane gas is continuously introduced into the reduced oxygen carrier to perform the catalytic cracking reaction, the reaction temperature is 600-900 DEG C, and generated gas II is obtained; a synthesis gas reaction, wherein the generated gas I is dried, when no hydrogen is generated, the dried generated gas I is used to perform the synthesis gas reaction, the reaction temperature is 500-900 DEG C, and generated gas III is obtained; and an oxidation reaction, wherein air is introduced at a gas speed of 10 mL / min, the reactor temperature is controlled to be 600-1000 DEG C, and generated gas IV and the oxygen carrier are obtained. The preparation method has the advantages that the methane conversion rate and the catalyst service life can be improved.

Description

Technical Field

[0001] This invention relates to the field of methane-to-hydrogen production, and more specifically, to a novel process and apparatus for the catalytic cracking of methane. Background Technology

[0002] With economic development, we need to develop a clean and pollution-free energy source. Hydrogen, as a highly efficient secondary energy source, has received increasing attention and is being used in various fields. Currently, there are four main methods of hydrogen production: hydrogen production from fossil fuels, hydrogen production from industrial by-products, hydrogen production from water electrolysis, hydrogen production from biomass, and others. Among these, hydrogen production from fossil fuels and hydrogen production from industrial by-products occupy the dominant positions in the hydrogen production structure due to their lower costs.

[0003] Currently, most industrial hydrogen is produced using traditional technologies, such as steam reforming (SMR) of methane. SMR uses natural gas as a feedstock but releases large amounts of carbon dioxide. In contrast, catalytic cracking of methane to produce hydrogen does not release any harmful gases, and its main byproducts can be widely used as industrial commodities in various fields.

[0004] However, the catalytic cracking reaction of methane requires a large amount of heat, producing high-value-added products but also resulting in significant energy consumption. Furthermore, while metal catalysts exhibit high activity and low reaction temperatures, they are prone to deactivation, leading to poor economic efficiency. Reducing the cost of hydrogen production from methane through catalytic cracking is thus a pressing issue that needs to be addressed. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a new process and apparatus for methane catalytic cracking, which solves the problems of high energy consumption, easy catalyst deactivation, poor economic efficiency, and high cost in the prior art. The energy supplied by the oxidation of the metal in the oxidation reactor replenishes the energy required by the fuel reactor, and the carbonized catalyst is regenerated to produce syngas, realizing the recycling of the metal catalyst and reducing catalyst consumption.

[0006] To achieve the above objectives and other related objectives,

[0007] A first aspect of the present invention provides a novel process for the catalytic cracking of methane, comprising the following steps:

[0008] The reduction reaction involves introducing reducing gas methane and 5g of oxygen carrier to carry out the reduction reaction. The reaction temperature is controlled at 500-700℃, and the reduction is carried out at atmospheric pressure for 2-4 hours to obtain product gas I and a catalytically active metal.

[0009] In the catalytic cracking reaction, when hydrogen is produced, the introduction of reducing gas methane is stopped, and the product gas I and the reducing oxygen carrier are separated. Then, methane gas is introduced again to react with the reducing oxygen carrier in the catalytic cracking reaction at a temperature of 600-900℃ to obtain product gas II.

[0010] Syngas reaction: Dry the product gas I. When no more hydrogen is produced, use the dried product gas I to carry out the syngas reaction. The reaction temperature is 500-900℃ to obtain product gas III.

[0011] The oxidation reaction involves introducing air at a rate of 10 mL / min and controlling the reactor temperature at 600-1000℃ to produce gas IV and an oxygen carrier.

[0012] By adopting the above technical solution, reducing gas is introduced into the reduction reactor through the inlet. The reaction temperature inside the reduction reactor is 500-700℃. The reducing gas reacts with the metal oxide to generate a catalytically active metal and product gas I. Product gas I enters a drying reactor for drying, while the catalytically active metal enters a fuel reactor. Methane is selected as the gas path for catalytic cracking reaction. At this time, the reaction temperature in the fuel reactor is 600-900℃. Methane reacts with the metal to produce product gas II, which is then cooled and collected.

[0013] After a period of reaction, the methane gas path is shut off, and the dried, dehydrated product gas I is passed through the fuel reactor for syngas reaction. Dehydrated product gas I reacts with the oxygen carrier to produce product gas III. At this point, the reaction temperature in the fuel reactor is 500-900℃. Product gas III is collected at the outlet. The oxygen carrier after the reaction enters the oxidation reactor, where air enters through the inlet and reacts with the oxygen carrier. The reaction temperature in the oxidation reactor is 600-1000℃. Product gas IV is discharged through the outlet. The oxidized oxygen carrier flows into the reduction reactor for a cyclic reaction. The energy supplied by the oxidation of the metal in the oxidation reactor replenishes the energy required by the fuel reactor and regenerates the carbonized catalyst to produce syngas, achieving the recycling of the metal catalyst and reducing catalyst consumption.

[0014] Preferably, the oxygen carrier includes at least one of NiO / Al2O3, Fe2O3 / Al2O3, and NiO-MgO.

[0015] By adopting the above technical solutions, NiO / Al2O3, Fe2O3 / Al2O3, and NiO-MgO achieve higher catalytic efficiency after reduction.

[0016] Preferably, the generated gas I is carbon dioxide and water, the generated gas II is hydrogen, the generated gas III is carbon monoxide and hydrogen, and the generated gas IV is carbon dioxide gas.

[0017] Preferably, during the reduction reaction, methane gas is introduced at a gas flow rate of 10 mL / min.

[0018] By adopting the above technical solution, the reduction reaction is more efficient and the conversion rate is higher, which is beneficial to improving the yield of catalytically active metals.

[0019] Preferably, during the catalytic cracking reaction, the flow rate of methane gas is 20 mL / min.

[0020] By adopting the above technical solutions, the efficiency of catalytic cracking reactions can be improved.

[0021] Preferably, the active component of the oxygen carrier is NiO, Fe2O3, NiO-Fe2O3, or NiO-CuO, and the support is Al2O3, MgO, activated carbon, or a mesoporous support.

[0022] In a second aspect, the present invention provides an apparatus for a novel methane catalytic cracking process as described above, comprising a reduction reactor, a drying reactor, a fuel reactor, and an oxidation reactor. The oxygen carrier outlet of the reduction reactor is connected to the oxygen carrier inlet of the fuel reactor, the oxygen carrier outlet of the fuel reactor is connected to the oxygen carrier inlet of the oxidation reactor, and the oxygen carrier outlet of the oxidation reactor is connected to the reduction reactor. Fresh oxygen carrier is directly added to the reduction reactor. The reduction reactor, drying reactor, fuel reactor, and oxidation reactor are all provided with gas inlets and outlets. The fuel reactor switches between different gases by adjusting valves.

[0023] By adopting the above technical solution, methane catalytic cracking for hydrogen production and syngas synthesis can be achieved in a single fuel reactor through gas conversion. This significantly reduces industrial footprint, lowers equipment costs, improves economic efficiency, and reduces energy consumption. The energy generated by the oxidation reactor can supply the energy required for methane catalytic cracking for hydrogen production in the fuel reactor. Carbon dioxide is used to remove carbon deposits on the catalyst surface, enabling catalyst recycling during syngas production and reducing the loss of metal catalysts.

[0024] Preferably, the reaction temperature of the reduction reactor is 500-700℃, the reaction temperatures of the fuel reactor are 600-900℃ and 500-900℃ respectively, and the reaction temperature of the oxidation reactor is 600-1000℃.

[0025] By adopting the above technical solution, the methane conversion rate and syngas production can achieve better results within this preferred range.

[0026] Preferably, the reaction temperature of the reduction reactor is 500-700℃, the reaction temperatures of the fuel reactor are 600-900℃ and 500-800℃ respectively, and the reaction temperature of the oxidation reactor is 600-800℃.

[0027] By adopting the above technical solution, the methane conversion rate and syngas production can achieve better results within this preferred range.

[0028] Preferably, the reduction reactor, drying reactor, fuel reactor, and oxidation reactor are made of stainless steel and have a temperature resistance range of room temperature to 1000℃.

[0029] Preferably, the drying reactor contains a drying medium, which is a high-temperature resistant water-absorbing material.

[0030] Preferably, the drying medium is 4A molecular sieve.

[0031] By adopting the above technical solution, since 4A molecular sieve has a high water vapor performance, it still has a large adsorption capacity under very low water vapor partial pressure, which can make the water content in the dried gas reach less than 1 ppm, and its service life is relatively long.

[0032] As described above, the novel methane catalytic cracking process and apparatus of the present invention have the following beneficial effects:

[0033] 1. Methane catalytic cracking to produce hydrogen and syngas synthesis can be achieved in a single fuel reactor through gas conversion, which greatly reduces the industrial footprint, lowers equipment costs, improves economic efficiency, and reduces energy consumption.

[0034] 2. The energy generated by the oxidation reactor can supply the energy required for the catalytic cracking of methane to produce hydrogen in the fuel reactor.

[0035] 3. Carbon dioxide is used to remove carbon deposits on the catalyst surface, enabling the recycling of the catalyst while generating syngas and reducing the loss of metal catalysts. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the self-powered methane catalytic cracking hydrogen production process device and hydrogen production process of the present invention.

[0037] Figure labels: 1. Reduction reactor; 2. Drying reactor; 3. Fuel reactor; 4. Oxidation reactor. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] The raw materials used in this application were obtained either through self-production or commercial channels.

[0040] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0041] Example

[0042] Example 1

[0043] An apparatus for a novel methane catalytic cracking process, such as... Figure 1 As shown, the reactor includes a reduction reactor 1, a drying reactor 2, a fuel reactor 3, and an oxidation reactor 4. The model and manufacturer of the reduction reactor 1 are FBR5100-Hunan Huasi, the model and manufacturer of the drying reactor 2 are ZPG-Qibao Drying, the model and manufacturer of the fuel reactor 3 are GR-A-Tianda Beiyang, and the model and manufacturer of the oxidation reactor 4 are OZ-102-Zhongke Sanyang.

[0044] The reduction reactor 1, drying reactor 2, fuel reactor 3, and oxidation reactor 4 are each equipped with an oxygen carrier outlet and an oxygen carrier inlet. The oxygen carrier outlet of the reduction reactor 1 is connected to the oxygen carrier inlet of the fuel reactor 3. The oxygen carrier outlet of the fuel reactor 3 is connected to the oxygen carrier inlet of the oxidation reactor 4, and the oxygen carrier outlet of the oxidation reactor 4 is connected to the oxygen carrier inlet of the reduction reactor 1.

[0045] The reduction reactor 1, drying reactor 2, fuel reactor 3, and oxidation reactor 4 are all made of stainless steel, with a temperature resistance range of room temperature to 1000℃. The drying reactor 2 contains a drying medium, which is a high-temperature resistant, water-absorbing material, 4A molecular sieve. Because 4A molecular sieve has very high water vapor resistance, it still has a large adsorption capacity even at very low water vapor partial pressures, allowing the water content in the dried gas to reach below 1 ppm, and it also has a relatively long service life.

[0046] During processing, fresh oxygen carrier is directly added to reduction reactor 1. In reduction reactor 1, reducing gas reacts with metal oxide to generate catalytically active metal and product gas I. Product gas I enters drying reactor 2 for drying. The catalytically active metal enters fuel reactor 3. Fuel reactor 3 switches between different gases through valve regulation. Methane is selected for the gas path to carry out catalytic cracking reaction. Methane reacts with metal to produce product gas II, which is then cooled and collected.

[0047] After a period of reaction, the methane gas path is closed, and the dried dehydrated product gas I is passed through the fuel reactor 3 for syngas reaction. The dehydrated product gas I reacts with the oxygen carrier to produce product gas III. Product gas III is collected at the outlet, and the oxygen carrier after the reaction enters the oxidation reactor 4. Air enters through the inlet of the oxidation reactor 4 to react with the oxygen carrier, and product gas IV is discharged from the outlet. The oxidized oxygen carrier flows into the reduction reactor 1 for a cyclic reaction.

[0048] Example 2

[0049] A novel process for catalytic cracking of methane includes the following steps:

[0050] Step 1: Reduction reaction. Take 5g of oxygen carrier NiO-Fe2O3 and put it into the reduction reactor. Introduce reducing gas methane at a gas rate of 10mL / min to carry out the reduction reaction. Control the reaction temperature at 550℃ and reduce at atmospheric pressure for 3h to obtain product gas I and a catalytically active metal. Product gas I is carbon dioxide and water.

[0051] Step 2: Catalytic cracking reaction. When hydrogen is detected by chromatography, the inlet is closed and the introduction of reducing gas methane is stopped. Generated gas I flows out from the outlet at the top of the reduction reactor, is dried and collected in a drying reactor, and is separated from the reduced oxygen carrier. The reduced oxygen carrier enters the fuel reactor, and then methane gas is introduced at 20 mL / min. The methane gas reacts with the reduced oxygen carrier in a catalytic cracking reaction at a temperature of 650℃ to obtain generated gas II, which is high-purity hydrogen. Generated gas II can be collected and stored from the outlet at the top of the fuel reactor.

[0052] Step 3: Syngas reaction. When hydrogen is no longer detectable by gas chromatography, switch the gas source and use dried product gas I for the syngas reaction. The reaction temperature is 700℃ to obtain product gas III, which consists of carbon monoxide and hydrogen. It is collected from the outlet.

[0053] Step 4: Oxidation reaction. After the synthesis gas reaction is completed, the oxygen carrier (catalyst) is sent into the oxidation reactor. Air is introduced at a gas rate of 10 mL / min, and the reactor temperature is controlled at 800℃. After contact with air, the catalyst is completely oxidized to obtain product gas IV and oxygen carrier. Then, it flows into the reduction reactor for recycling reaction. The product gas IV produced by the oxidation reactor is a small amount of carbon dioxide gas, which can be directly discharged into the atmosphere.

[0054] Example 3

[0055] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with Fe2O3 / Al2O3 and the temperature of the methane catalytic cracking reaction in the fuel reactor in step two is controlled at 750°C.

[0056] Example 4

[0057] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with Fe2O3 / Al2O3 and the temperature of the methane catalytic cracking reaction in the fuel reactor in step two is controlled at 800°C.

[0058] Example 5

[0059] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with Fe2O3 / Al2O3, and the methane catalytic cracking reaction temperature in the fuel reactor in step two is controlled at 750°C and 800°C.

[0060] Example 6

[0061] A new process for catalytic cracking of methane, with other steps the same as in Example 2, except that the oxygen carrier is replaced with NiO-MgO.

[0062] Example 7

[0063] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with NiO-MgO and the temperature of the methane catalytic cracking reaction in the fuel reactor in step two is controlled at 750°C.

[0064] Example 8

[0065] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with NiO-MgO and the temperature of the methane catalytic cracking reaction in the fuel reactor in step two is controlled at 800°C.

[0066] Example 9

[0067] A new process for catalytic cracking of methane is described, with other steps the same as in Example 2, except that the oxygen carrier is replaced with NiO-MgO, and the methane catalytic cracking reaction temperature in the fuel reactor in step two is controlled at 750°C and 800°C.

[0068] Comparative Example

[0069] Comparative Example 1

[0070] A novel process for catalytic cracking of methane is disclosed, involving a fixed-bed reaction using Ni / Al₂O₃ as the catalyst and methane as the fuel gas. 5 g of catalyst was introduced, and methane was introduced into the fixed-bed reactor at a gas flow rate of 50 mL / min. The reactor temperature was 750 °C, and the reaction was carried out for 3 hours. The products were collected and analyzed by gas chromatography.

[0071] Performance testing method results

[0072] Table 1

[0073]

[0074]

[0075] In summary, this invention improves methane conversion rate and catalyst lifespan. It enables the catalytic cracking of methane to produce hydrogen and the synthesis of syngas within a single fuel reactor through gas conversion, significantly reducing industrial footprint, lowering equipment costs, improving economic efficiency, and reducing energy consumption. The energy generated by the oxidation reactor can supply the energy required for the catalytic cracking of methane to produce hydrogen in the fuel reactor. Utilizing carbon dioxide to remove carbon deposits on the catalyst surface allows for catalyst recycling during syngas production, reducing the loss of metal catalysts. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A process for the catalytic cracking of methane, characterized in that, The method comprises the following steps: The reduction reaction is performed by introducing the reducing gas methane into the reduction reactor to react with 5 g of the oxygen carrier, the reaction temperature is controlled at 500-700 DEG C, the reduction is performed under normal pressure for 2-4 h, and the generated gas I and the metal with catalytic activity are obtained; the oxygen carrier comprises at least one of NiO / Al2O3, Fe2O3 / Al2O3 and NiO-MgO; the generated gas I is carbon dioxide and water; When the hydrogen gas is generated in the reduction reactor, the catalytic cracking reaction is performed by stopping the introduction of the reducing gas methane, separating the generated gas I and the reduced oxygen carrier, introducing the generated gas I into the drying reactor for drying, and introducing the reduced oxygen carrier into the fuel reactor; then the methane gas is continuously introduced into the fuel reactor to react with the reduced oxygen carrier, the reaction temperature is 600-900 DEG C, and the generated gas II is obtained; the generated gas II is hydrogen gas; The synthesis gas reaction is performed by drying the generated gas I, and when no hydrogen gas is generated in the fuel reactor, the dried generated gas I is used to perform the synthesis gas reaction, the reaction temperature is 500-900 DEG C, and the generated gas III is obtained; the generated gas III is carbon monoxide and hydrogen gas; and the oxygen carrier after the reaction is introduced into the oxidation reactor; The oxidation reaction is performed by introducing the air into the oxidation reactor at a gas speed of 10 mL / min, the temperature of the oxidation reactor is controlled at 600-1000 DEG C, the generated gas IV and the oxygen carrier are obtained; the generated gas IV is carbon dioxide gas; and the oxygen carrier after the oxidation is introduced into the reduction reactor.

2. Process for the catalytic decomposition of methane according to claim 1, characterized in that: In the reduction reaction, the reducing gas methane is introduced at a gas speed of 10 mL / min.

3. The process for catalytic decomposition of methane according to claim 1, characterized by that: In the catalytic cracking reaction, the methane gas is introduced at a flow rate of 20 mL / min.

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