Method and device for producing methane from a mixture of h2s and co2

Abstract

The present application relates to a new method for preparing methane, a method for preparing methane from H2S and CO2 mixed gas, a metal modified molecular sieve is placed in the reaction cavity of a wire cylinder type reactor, nitrogen is introduced to remove air in the reactor, then H2S and CO2 mixed gas is introduced, a plasma power connected with a high voltage electrode and a grounding electrode is turned on, the reaction gas is purified by a low temperature methanol washing method, pure CH4 gas is obtained, and the washed H2S and CO2 gas is returned to the raw gas for reaction. The present application also relates to a wire cylinder type reactor, i.e. a reaction device, used in the method for preparing methane from H2S and CO2 mixed gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to a new method for preparing methane, and particularly relates to a method for preparing methane from H2S and CO2 mixed gas by using metal-modified molecular sieve and plasma. BACKGROUND

[0002] Hydrogen sulfide (H2S) is a toxic and malodorous acid gas, and the combustion of which generates SO x which is a main component of acid rain, often causing environmental pollution and endangering human safety. In addition, H2S not only causes corrosion of equipment and pipelines in industry, but also poisons and deactivates metal catalysts in catalytic reactions. Carbon dioxide (CO2) is a well-known greenhouse gas, and a large amount of which is generated from the combustion of fossil fuels with the development of human society. At the same time, CO2 causes global temperature rise, sea level rise and ocean acidification, which seriously threatens the living environment of human beings.

[0003] In the process of coal, oil and natural gas development and utilization, H2S and CO2 are often generated in large amounts and coexist. Currently, the Claus process is often used to treat H2S and CO2 mixed acid gas in industry, but only sulfur is recovered in this process, and CO2 reduction and hydrogen energy recovery are not achieved. The applicant has realized the preparation of synthesis gas from H2S and CO2 mixed gas in the previous study, please refer to the granted invention patent ZL201710469388.3. In further research, the applicant creatively uses a new catalytic system to directly convert H2S and CO2 mixed gas to obtain methane (CH4).

[0004] CH4 is the main fuel in China at present, and can also be used as an important raw material for the manufacture of hydrogen, methanol, formaldehyde, hydrocyanic acid, urea, acetylene, carbon black, carbon monoxide and pharmaceutical intermediates in China, but at present CH4 largely depends on imports from other countries. Therefore, in the present application, CH4 is directly prepared from waste pollutants H2S and CO2 mixed gas, which not only realizes the harmless treatment of waste pollutants H2S and CO2, but also directly produces an important industrial raw material, methane, providing a new way for China's natural gas industry to obtain CH4. This new method for preparing CH4 is also an ideal route for utilizing H2S and CO2 mixed waste gas, which has important significance in the field of methane synthesis and clean and environmental utilization of industrial waste gas in China.

[0005] The present application is to use H2S and CO2 mixed gas as raw material, and to directly convert H2S and CO2 mixed gas into CH4 by using a metal-modified molecular sieve catalyst combined with plasma. CH4 is produced and the harmless treatment of H2S and CO2 is realized, and no similar technology is found through retrieval. SUMMARY

[0006] The present application aims to provide a new method for synthesizing CH4 while harmless H2S and CO2 mixed gas.

[0007] Plasma is the fourth state of matter in addition to gas, liquid and solid, and is rich in a large number of excited species such as excited radicals, ions, atoms, molecules and high-energy electrons. The present application uses a metal-modified molecular sieve catalyst combined with plasma to excite H2S and CO2 mixed gas to produce high-activity plasma species, and combines the catalytic action of the metal-modified molecular sieve catalyst to realize the direct synthesis of CH4 from H2S and CO2 mixed gas.

[0008] The process is described as follows: H2S and CO2 mixed gas is excited by plasma discharge to produce excited active species, and a metal-modified molecular sieve catalyst is filled in the plasma discharge area. The excited active species produces product methane under the catalytic action of the molecular sieve catalyst, realizing the process of directly preparing methane from H2S and CO2 mixed gas. The plasma discharge can use an alternating current power supply or a direct current power supply. The metal-modified molecular sieve catalyst filled in the plasma discharge area is a solid particle or a solid powder.

[0009] A method for preparing methane from H2S and CO2 mixed gas, a metal-modified molecular sieve is placed in the reaction cavity of a wire cylinder reactor, nitrogen is introduced to remove air in the reactor, and then H2S and CO2 mixed gas is introduced, wherein the volume percentage of H2S in the mixed gas is 40-99%, the volume percentage of CO2 is 1-60%, the flow rate of the mixed gas is 100-10000h -1 , the reaction pressure is 0.1-3 MPa, the reaction temperature is 120-250℃, the plasma power supply connected to the high-voltage electrode and the grounding electrode is turned on, the voltage is adjusted to 0.5-100 kilovolts, and the frequency is 0.5-30 kilohertz. After the reaction, the gas is purified by low-temperature methanol washing method to obtain pure CH4 gas, and the washed H2S and CO2 gas is returned to the raw gas for reaction.

[0010] When the low-temperature methanol washing method is used for purification, the operating temperature is -29 to -65℃, the operating pressure is 1-7.5 MPa, the H2S in the purified synthesis gas is <0.2 ppm, and the CO2 is <0.3 vol%.

[0011] The metal-modified molecular sieve is one of 3A type molecular sieve, 4A type molecular sieve, 5A type molecular sieve, 10X type molecular sieve, 13X type molecular sieve, 10X type molecular sieve, M type molecular sieve, Y type molecular sieve or a mixture of two of them.

[0012] The metal in the metal-modified molecular sieve is one of Pt, Pd, Rh, Ag, Mn, Zn, Cu, Ni, Co, Fe or a mixture of two of them.

[0013] A linear cylinder type reactor used in a method for preparing CH4 from H2S and CO2 mixed gas, characterized in that the linear cylinder type reactor is provided with a gas inlet (1), a high-voltage electrode (2), a grounding electrode (3), a shell (4), and a gas outlet (5), the shell (4) is provided with a columnar conductor as the high-voltage electrode (2) on the axis of the shell (4), the shell (4) is provided with a coil as the grounding electrode (3) on the outside of the shell (4), the shell (4) is provided with a cylindrical reaction cavity inside, the shell (4) is provided with the gas inlet (1) on the upper end of the shell (4), the shell (4) is provided with the gas outlet (5) on the lower end of the shell (4), the high-voltage electrode (2) is connected to high-voltage electricity through a wire, and the grounding electrode (3) is grounded through a wire.

[0014] The shell (4) is made of glass, quartz glass, ceramic or corundum.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. A new method for preparing CH4 is invented.

[0017] 2. The synthesis of industrial raw material CH4 is realized, and the H2S and CO2 mixed waste gas is harmlessly treated at the same time.

[0018] 3. The conversion of H2S and CO2 and the generation of CH4 are promoted by introducing the metal modified molecular sieve catalyst.

[0019] 4. In the present application, the conversion rate of carbon dioxide is higher than 50%, the conversion rate of hydrogen sulfide is higher than 80%, and the selectivity of methane is higher than 50%. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the linear cylinder type plasma discharge reactor of the present application.

[0021] Figure 2 It is a graph of the catalytic performance of the 8wt% Ni-1wt% Pt doped 5wt% 13X type-86wt% 3A type molecular sieve catalyst in Example 24 with the change of reaction time when H2S and CO2 are converted in the plasma.

[0022] In the figure, 1 is the gas inlet, 2 is the high-voltage electrode, 3 is the grounding electrode, 4 is the shell, and 5 is the gas outlet. DETAILED DESCRIPTION

[0023] The specific embodiments of the present application are described in detail below in combination with the technical solutions. The content of methane in the tail gas is analyzed online by chromatography.

[0024] Example 1

[0025] The wire cylinder reactor is composed of an air inlet 1, a high voltage electrode 2, a grounding electrode 3, a shell 4, and an air outlet 5. The high voltage electrode 2 is installed on the axis of the shell 4, and the grounding electrode 3 is wound outside. The high voltage electrode 2 and the grounding electrode 3 are respectively fixed with electric wires. The shell 4 is a cylindrical reaction cavity. The shell 4 has an air inlet 1 at the upper end and an air outlet 5 at the lower end. The high voltage electrode 2 is connected to high voltage through the electric wires, and the grounding electrode 3 is grounded through the electric wires.

[0026] A 1wt% Pt-doped 3A molecular sieve catalyst was placed in the reaction cavity, and the shell 4 was made of quartz glass. Nitrogen was introduced for 10 minutes to remove air in the reactor. The flow rate was controlled by a mass flow meter, and a mixed gas with a composition of 50vol% H2S-30vol% CO2-20vol% Ar was introduced at a flow rate of 500 h -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 0.2 MPa, the reaction temperature was 130°C, the plasma power source connected to the high voltage electrode and the grounding electrode was turned on, the voltage was adjusted to 50 kilovolts, and the frequency was 1 kilohertz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by a low-temperature methanol washing method, the operating temperature was -47°C, and the operating pressure was 6.0 MPa. The reaction results are shown in Table 1:

[0027] Table 1 H2S and CO2 conversion, CH4 selectivity

[0028] H2S conversion, % CO2 conversion, % CH4 selectivity, % 82.8 61.5 60.2

[0029] Example 2

[0030] A 0.5wt% Pd-doped 5A molecular sieve catalyst was placed in the reaction cavity, and the shell 4 was made of corundum. Nitrogen was introduced for 10 minutes to remove air in the reactor. The flow rate was controlled by a mass flow meter, and a mixed gas with a composition of 80vol% H2S-20vol% CO2 was introduced at a flow rate of 1000 h -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2 MPa, the reaction temperature was 140°C, the plasma power source connected to the high voltage electrode and the grounding electrode was turned on, the voltage was adjusted to 70 kilovolts, and the frequency was 0.5 kilohertz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by a low-temperature methanol washing method, the operating temperature was -40°C, and the operating pressure was 7.5 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 2:

[0031] Table 2 H2S and CO2 conversion, CH4 selectivity

[0032] H2S conversion, % CO2 conversion, % CH4 selectivity, % 75.3 65.8 71.9

[0033] Example 3

[0034] A 5wt% Rh doped Y zeolite catalyst was placed in the reaction chamber, the housing 4 was made of ceramic, and nitrogen was introduced for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 60 vol% H2S - 30 vol% CO2 - 10 vol% N2 was introduced at 10000 h -1 The flow rate was controlled by mass flow meters, and a mixture of 60 vol% H2S - 30 vol% CO2 - 10 vol% N2 was introduced at 10000 h

[0035] Table 3 H2S and CO2 conversion, CH4 selectivity

[0036] H2S conversion, % CO2 conversion, % CH4 selectivity, % 94.6 68.9 60.3

[0037] Example 4

[0038] A 9wt% Ag doped 4A zeolite catalyst was placed in the reaction chamber, the housing 4 was made of glass, and nitrogen was introduced for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 65 vol% H2S - 35 vol% CO2 was introduced at 10000 h -1 The flow rate was controlled by mass flow meters, and a mixture of 60 vol% H2S - 30 vol% CO2 - 10 vol% N2 was introduced at 10000 h

[0039] Table 4 H2S and CO2 conversion, CH4 selectivity

[0040] H2S conversion, % CO2 conversion, % CH4 selectivity, % <!-- 3 --> 53.2 33.7 48.1

[0041] Example 5

[0042] A 20wt% Mn doped 13X zeolite catalyst was placed in the reaction chamber, the housing 4 was made of corundum, and nitrogen was introduced for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 85 vol% H2S - 15 vol% CO2 was introduced at 5000 h -1The flow rate of the space velocity passed through the bed. The reaction pressure was 1.7 MPa, the reaction temperature was 230 °C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 90 kilovolts, and the frequency was 20 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -51 °C and an operating pressure of 1.2 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 5:

[0043] Table 5 H2S and CO2 conversion, CH4 selectivity

[0044] H2S conversion, % CO2 conversion, % CH4 selectivity, % 48.8 31.6 58.2

[0045] Example 6

[0046] A 2 wt% Zn-doped 10X molecular sieve catalyst was placed in the reaction chamber, the shell 4 was made of corundum, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 1.7 MPa, the reaction temperature was 230 °C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 90 kilovolts, and the frequency was 20 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -51 °C and an operating pressure of 1.2 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 5: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2.8 MPa, the reaction temperature was 155 °C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 5 kilovolts, and the frequency was 6 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -35 °C and an operating pressure of 3.3 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 6:

[0047] Table 6 H2S and CO2 conversion, CH4 selectivity

[0048] H2S conversion, % CO2 conversion, % CH4 selectivity, % 81.3 47.5 60.7

[0049] Example 7

[0050] A 3 wt% Cu-doped M-type molecular sieve catalyst was placed in the reaction chamber, the shell 4 was made of ceramic, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 2.5 MPa, the reaction temperature was 225 °C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 2 kilovolts, and the frequency was 7 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -52 °C and an operating pressure of 5.8 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 7: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2.8 MPa, the reaction temperature was 155 °C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 5 kilovolts, and the frequency was 6 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -35 °C and an operating pressure of 3.3 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 6:

[0051] Table 7 H2S and CO2 conversion, CH4 selectivity

[0052] H2S conversion, % CO2 conversion, % CH4 selectivity, % 40.2 28.5 40.6

[0053] Example 8

[0054] A 0.1 wt% Ni doped Y-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of quartz glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 40 vol% H2S-60 vol% CO2 was passed at 9000 h -1 The flow rate was controlled by mass flow meters, and a gas mixture of 40 vol% H2S-60 vol% CO2 was passed at 9000 h

[0055] Table 8 H2S and CO2 conversion, CH4 selectivity

[0056] H2S conversion, % CO2 conversion, % CH4 selectivity, % 71.3 19.2 41.1

[0057] Example 9

[0058] A 10 wt% Co doped M-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of quartz glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 92 vol% H2S-8 vol% CO2 was passed at 200 h -1 The flow rate was controlled by mass flow meters, and a gas mixture of 40 vol% H2S-60 vol% CO2 was passed at 9000 h

[0059] Table 9 H2S and CO2 conversion, CH4 selectivity

[0060] H2S conversion, % CO2 conversion, % CH4 selectivity, % 22.4 34.7 39.4

[0061] Example 10

[0062] A 15 wt% Fe doped 13X-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 99 vol% H2S-1 vol% CO2 was passed at 8000 h -1The flow rate of the space velocity passed through the bed. The reaction pressure was 1 MPa, the reaction temperature was 120°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 0.5 kV, and the frequency was 8 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low-temperature methanol wash process, the operating temperature was -48°C, and the operating pressure was 4.5 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 10:

[0063] Table 10 H2S and CO2 conversion, CH4 selectivity

[0064] H2S conversion, % CO2 conversion, % CH4 selectivity, % 18.1 83.7 90.6

[0065] Example 11

[0066] A 10X molecular sieve catalyst doped with 1.5 wt% Fe-3.5 wt% Co was placed in the reaction chamber, the shell 4 was made of corundum, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 1 MPa, the reaction temperature was 120°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 0.5 kV, and the frequency was 8 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low-temperature methanol wash process, the operating temperature was -48°C, and the operating pressure was 4.5 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 10: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2.2 MPa, the reaction temperature was 215°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 55 kV, and the frequency was 13 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low-temperature methanol wash process, the operating temperature was -65°C, and the operating pressure was 3 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 11:

[0067] Table 11 H2S and CO2 conversion, CH4 selectivity

[0068] H2S conversion, % CO2 conversion, % CH4 selectivity, % 98.2 63.1 80.7

[0069] Example 12

[0070] A 4A molecular sieve catalyst doped with 0.9 wt% Ni-9.1 wt% Mn was placed in the reaction chamber, the shell 4 was made of ceramic, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 1 MPa, the reaction temperature was 120°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 0.5 kV, and the frequency was 8 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low-temperature methanol wash process, the operating temperature was -48°C, and the operating pressure was 4.5 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 10: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 3.0 MPa, the reaction temperature was 205°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 30 kV, and the frequency was 22 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low-temperature methanol wash process, the operating temperature was -33°C, and the operating pressure was 2.2 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 12:

[0071] Table 12 H2S and CO2 conversion, CH4 selectivity

[0072] H2S conversion, % CO2 conversion, % CH4 selectivity, % 89.7 29.8 50.6

[0073] Example 13

[0074] A 5.7 wt% Pt-6.3 wt% Pd doped 5A molecular sieve catalyst was placed in the reaction chamber, the housing 4 was ceramic, and the reactor was purged with nitrogen for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters and a gas mixture of composition 47 vol% H2S-48 vol% CO2-5 vol% H2 was passed over the catalyst bed at a space velocity of 9000 h"1. The reaction pressure was 0.1 MPa, the reaction temperature was 170°C, the plasma power was turned on with the high voltage electrode connected to the ground electrode, the voltage was adjusted to 85 kV and the frequency was 15 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by cryogenic methanol wash at a temperature of -54°C and a pressure of 5 MPa. The rest was as in Example 1 and the results are given in Table 13: -1 The flow rate was controlled by mass flow meters and a gas mixture of composition 47 vol% H2S-48 vol% CO2-5 vol% H2 was passed over the catalyst bed at a space velocity of 9000 h"1. The reaction pressure was 0.1 MPa, the reaction temperature was 170°C, the plasma power was turned on with the high voltage electrode connected to the ground electrode, the voltage was adjusted to 85 kV and the frequency was 15 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by cryogenic methanol wash at a temperature of -54°C and a pressure of 5 MPa. The rest was as in Example 1 and the results are given in Table 13:

[0075] Table 13 H2S and CO2 conversion, CH4 selectivity

[0076] H2S conversion, % CO2 conversion, % CH4 selectivity, % 97.6 59.9 81.1

[0077] Example 14

[0078] A 9.5 wt% Co-5.5 wt% Zn doped Y molecular sieve catalyst was placed in the reaction chamber, the housing 4 was ceramic, and the reactor was purged with nitrogen for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters and a gas mixture of composition 87 vol% H2S-13 vol% CO2 was passed over the catalyst bed at a space velocity of 2000 h"1. The reaction pressure was 1.6 MPa, the reaction temperature was 240°C, the plasma power was turned on with the high voltage electrode connected to the ground electrode, the voltage was adjusted to 45 kV and the frequency was 12 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by cryogenic methanol wash at a temperature of -45°C and a pressure of 1.5 MPa. The rest was as in Example 1 and the results are given in Table 14: -1 The flow rate was controlled by mass flow meters and a gas mixture of composition 47 vol% H2S-48 vol% CO2-5 vol% H2 was passed over the catalyst bed at a space velocity of 9000 h"1. The reaction pressure was 0.1 MPa, the reaction temperature was 170°C, the plasma power was turned on with the high voltage electrode connected to the ground electrode, the voltage was adjusted to 85 kV and the frequency was 15 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by cryogenic methanol wash at a temperature of -54°C and a pressure of 5 MPa. The rest was as in Example 1 and the results are given in Table 13:

[0079] Table 14 H2S and CO2 conversion, CH4 selectivity

[0080] H2S conversion, % CO2 conversion, % CH4 selectivity, % 72.4 81.5 92.3

[0081] Example 15

[0082] A 19.8 wt% Cu-0.2 wt% Pt doped 3A molecular sieve catalyst was placed in the reaction chamber, the housing 4 was of ceramic material, and the reactor was purged with nitrogen for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 95 vol% H2S-5 vol% CO2was fed at 6000 h -1 The flow rate was controlled by mass flow meters, and a gas mixture of 95 vol% H2S-5 vol% CO2was fed at 6000 h

[0083] Table 15 H2S and CO2conversion, CH4selectivity

[0084] H2S conversion, % CO2 conversion, % CH4 selectivity, % 63.3 90.5 95.0

[0085] Example 16

[0086] A 2.4 wt% Co-0.8 wt% Fe doped M-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was of corundum material, and the reactor was purged with nitrogen for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 73 vol% H2S-27 vol% CO2was fed at 300 h -1 The flow rate was controlled by mass flow meters, and a gas mixture of 95 vol% H2S-5 vol% CO2was fed at 6000 h

[0087] Table 16 H2S and CO2conversion, CH4selectivity

[0088] H2S conversion, % CO2 conversion, % CH4 selectivity, % 70.0 71.8 73.6

[0089] Example 17

[0090] A 3.6 wt% Zn-5.0 wt% Ni doped 13X molecular sieve catalyst was placed in the reaction chamber, the housing 4 was of glass material, and the reactor was purged with nitrogen for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a gas mixture of 30 vol% H2S-45 vol% CO2-25 vol% CO was fed at 800 h -1The flow rate of the space velocity passed through the bed. The reaction pressure was 1.4 MPa, the reaction temperature was 180°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 60 kV, and the frequency was 3.0 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low temperature methanol wash process at an operating temperature of -62°C and an operating pressure of 4 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 17:

[0091] Table 17 H2S and CO2 conversion, CH4 selectivity

[0092] H2S conversion, % CO2 conversion, % CH4 selectivity, % 75.2 53.8 84.1

[0093] Example 18

[0094] A 10X molecular sieve catalyst doped with 0.2 wt% Cu-0.1 wt% Pd was placed in the reaction chamber, the shell 4 was made of quartz glass, and nitrogen was introduced for 10 minutes to remove air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 1.4 MPa, the reaction temperature was 180°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 60 kV, and the frequency was 3.0 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low temperature methanol wash process at an operating temperature of -62°C and an operating pressure of 4 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 17: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2.3 MPa, the reaction temperature was 150°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 35 kV, and the frequency was 24 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low temperature methanol wash process at an operating temperature of -65°C and an operating pressure of 5.5 MPa.

[0095] The rest was the same as in Example 1, and the reaction results are shown in Table 18:

[0096] Table 18 H2S and CO2 conversion, CH4 selectivity

[0097] H2S conversion, % CO2 conversion, % CH4 selectivity, % 68.8 65.6 57.9

[0098] Example 19

[0099] A 4A molecular sieve catalyst doped with 9.5 wt% Cu-1.5 wt% Zn was placed in the reaction chamber, the shell 4 was made of ceramic, and nitrogen was introduced for 10 minutes to remove air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 1.4 MPa, the reaction temperature was 180°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 60 kV, and the frequency was 3.0 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low temperature methanol wash process at an operating temperature of -62°C and an operating pressure of 4 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 17: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 2.3 MPa, the reaction temperature was 150°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 35 kV, and the frequency was 24 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a low temperature methanol wash process at an operating temperature of -65°C and an operating pressure of 5.5 MPa.

[0100] Table 19 H2S and CO2 conversion, CH4 selectivity

[0101] H2S conversion, % CO2 conversion, % CH4 selectivity, % 41.6 79.4 83.2

[0102] Example 20

[0103] A 10wt% 3A-82wt% 3A zeolite catalyst doped with 3.5wt% Pt-4.5wt% Rh was placed in the reaction chamber, the housing 4 was made of corundum, and nitrogen was passed through for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 49vol% H2S-51vol% CO2 was passed through the bed at a space velocity of 1500 h"1. The reaction pressure was 1.8 MPa, the reaction temperature was 129°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 49.5 kV, and the frequency was 1 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process, the operating temperature was -46°C, and the operating pressure was 6.1 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 20: -1 The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 49vol% H2S-51vol% CO2 was passed through the bed at a space velocity of 1500 h"1. The reaction pressure was 1.8 MPa, the reaction temperature was 129°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 49.5 kV, and the frequency was 1 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process, the operating temperature was -46°C, and the operating pressure was 6.1 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 20:

[0104] Table 20 H2S and CO2 conversion, CH4 selectivity

[0105] H2S conversion, % CO2 conversion, % CH4 selectivity, % 83.7 48.9 65.2

[0106] Example 21

[0107] A 16wt% 5A-64wt% 10X zeolite catalyst doped with 2.5wt% Rh-17.5wt% Rh was placed in the reaction chamber, the housing 4 was made of glass, and nitrogen was passed through for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 81vol% H2S-19vol% CO2 was passed through the bed at a space velocity of 1500 h"1. The reaction pressure was 2.1 MPa, the reaction temperature was 141°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 69.5 kV, and the frequency was 0.5 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process, the operating temperature was -41°C, and the operating pressure was 7.4 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 21: -1 The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 49vol% H2S-51vol% CO2 was passed through the bed at a space velocity of 1500 h"1. The reaction pressure was 1.8 MPa, the reaction temperature was 129°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 49.5 kV, and the frequency was 1 kHz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process, the operating temperature was -46°C, and the operating pressure was 6.1 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 20:

[0108] Table 21 H2S and CO2 conversion, CH4 selectivity

[0109] H2S conversion, % CO2 conversion, % CH4 selectivity, % 61.9 50.0 73.8

[0110] Example 22

[0111] A 38 wt% Y-type - 59 wt% 13X-type zeolite catalyst doped with 0.8 wt% Rh - 2.2 wt% Fe was placed in the reaction chamber, the housing 4 was made of quartz glass, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a mixture of 59 vol% H2S - 41 vol% CO2 was introduced at a rate of 150 h -1 The flow rate was controlled by a mass flow meter, and a mixture of 59 vol% H2S - 41 vol% CO2 was introduced at a rate of 150 h

[0112] Table 22 H2S and CO2 conversion, CH4 selectivity

[0113] H2S conversion, % CO2 conversion, % CH4 selectivity, % 60.4 41.7 50.9

[0114] Example 23

[0115] A 50 wt% 4A-type - 32 wt% 13M-type zeolite catalyst doped with 4 wt% Pt - 14 wt% Cu was placed in the reaction chamber, the housing 4 was made of corundum, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a mixture of 64 vol% H2S - 41 vol% CO2 was introduced at a rate of 9850 h -1 The flow rate was controlled by a mass flow meter, and a mixture of 59 vol% H2S - 41 vol% CO2 was introduced at a rate of 150 h

[0116] Table 23 H2S and CO2 conversion, CH4 selectivity

[0117] H2S conversion, % CO2 conversion, % CH4 selectivity, % 73.8 58.6 77.4

[0118] Example 24

[0119] A 5 wt% 13X-type - 86 wt% 3A-type zeolite catalyst doped with 8 wt% Ni - 1 wt% Pt was placed in the reaction chamber, the housing 4 was made of ceramic, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a mixture of 84 vol% H2S - 16 vol% CO2 was introduced at a rate of 5500 h -1The air velocity flow rate passed through the bed. The reaction pressure was 1.8 MPa, the reaction temperature was 232 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 91.5 kV and the frequency to 20.5 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -52 °C and an operating pressure of 1.3 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 24.

[0120] Table 24 H2S and CO2 conversion rates, CH4 selectivity

[0121] H2S conversion, % CO2 conversion, % CH4 selectivity, % 55.7 86.2 99.0

[0122] Example 25

[0123] An 8wt% Ni-1wt% Pt-doped 5wt% 13X-86wt% 3A type molecular sieve catalyst was placed in the reaction chamber. The shell 4 was made of ceramic. Nitrogen gas was introduced for 10 minutes to remove air from the reactor. A mixture of 84 vol% H2S and 16 vol% CO2 was used, controlled by a mass flow meter, at a flow rate of 5500 h⁻¹. -1 The air velocity flow rate passed through the bed. The reaction pressure was 1.8 MPa, the reaction temperature was 232 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 91.5 kV and the frequency to 20.5 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -52 °C and an operating pressure of 1.3 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 25.

[0124] Table 25 H2S and CO2 conversion rates, CH4 selectivity

[0125] H2S conversion, % CO2 conversion, % CH4 selectivity, % 78.8 51.6 81.2

[0126] Example 26

[0127] A 63wt% 10X-17.6wt% Y-type molecular sieve catalyst doped with 19wt% Co and 0.4wt% Pt was placed in the reaction chamber. The shell 4 was made of glass. Nitrogen gas was introduced for 10 minutes to remove air from the reactor. A mixture of 79vol% H2S and 21vol% CO2 was used, controlled by a mass flow meter, at a flow rate of 3500 h⁻¹. -1 The air velocity flow rate passed through the bed. The reaction pressure was 2.7 MPa, the reaction temperature was 156 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 4.5 kV and the frequency to 6.5 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -36 °C and an operating pressure of 3.2 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 26.

[0128] Table 26 H2S and CO2 conversion, CH4 selectivity

[0129] H2S conversion, % CO2 conversion, % CH4 selectivity, % 33.9 20.1 69.4

[0130] Example 27

[0131] A 5wt% Pd-1wt% Rh doped 80wt% M-type-14wt% 5A-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of quartz glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 62vol% H2S-38vol% CO2 was passed at 7500 h -1 The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 62vol% H2S-38vol% CO2 was passed at 7500 h

[0132] Table 27 H2S and CO2 conversion, CH4 selectivity

[0133] H2S conversion, % CO2 conversion, % CH4 selectivity, % 43.3 15.6 58.8

[0134] Example 28

[0135] A 4wt% Ag-0.2wt% Pd doped 12wt% Y-type-83.8wt% 4A-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 39vol% H2S-61vol% CO2 was passed at 9500 h -1 The flow rate was controlled by mass flow meters, and a gas mixture with a composition of 62vol% H2S-38vol% CO2 was passed at 7500 h

[0136] Table 28 H2S and CO2 conversion, CH4 selectivity

[0137] H2S conversion, % CO2 conversion, % CH4 selectivity, % 98.9 30.5 50.1

[0138] Example 29

[0139] A 40 wt% M-type - 43 wt% 10X-type zeolite catalyst doped with 0.2 wt% Cu - 16.8 wt% Ni was placed in the reaction chamber, the shell 4 was made of corundum, and nitrogen was passed through for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a gas mixture with a composition of 93 vol% H2S - 7 vol% CO2 was passed through at 250 h -1 The flow rate was controlled by a mass flow meter, and a gas mixture with a composition of 93 vol% H2S - 7 vol% CO2 was passed through at 250 h

[0140] Table 29 H2S and CO2 conversion, CH4 selectivity

[0141] H2S conversion, % CO2 conversion, % CH4 selectivity, % 68.9 89.5 72.1

[0142] Example 30

[0143] A 54 wt% 13X-type - 33 wt% 5A-type zeolite catalyst doped with 9 wt% Co - 4 wt% Cu was placed in the reaction chamber, the shell 4 was made of quartz glass, and nitrogen was passed through for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a gas mixture with a composition of 98 vol% H2S - 2 vol% CO2 was passed through at 8500 h -1 The flow rate was controlled by a mass flow meter, and a gas mixture with a composition of 93 vol% H2S - 7 vol% CO2 was passed through at 250 h

[0144] Table 30 H2S and CO2 conversion, CH4 selectivity

[0145] H2S conversion, % CO2 conversion, % CH4 selectivity, % 37.2 98.8 96.5

[0146] Example 31

[0147] A 60 wt% 10X-type - 10 wt% 4A-type zeolite catalyst doped with 16 wt% Cu - 14 wt% Fe was placed in the reaction chamber, the shell 4 was made of glass, and nitrogen was passed through for 10 minutes to remove the air in the reactor. The flow rate was controlled by a mass flow meter, and a gas mixture with a composition of 41 vol% H2S - 59 vol% CO2 was passed through at 740 h -1The flow rate of the space velocity passed through the bed. The reaction pressure was 2.1 MPa, the reaction temperature was 216°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 54.5 kilovolts, and the frequency was 13 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -53°C and an operating pressure of 3.1 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 31:

[0148] Table 31 H2S and CO2 conversion, CH4 selectivity

[0149] H2S conversion, % CO2 conversion, % CH4 selectivity, % 86.3 49.1 69.2

[0150] Example 32

[0151] A 48 wt% 4A-31 wt% 13X molecular sieve catalyst doped with 1 wt% Co-20 wt% Ni was placed in the reaction chamber, the shell 4 was made of ceramic, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 2.1 MPa, the reaction temperature was 216°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 54.5 kilovolts, and the frequency was 13 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -53°C and an operating pressure of 3.1 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 31: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 3.0 MPa, the reaction temperature was 205°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 29 kilovolts, and the frequency was 22 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -32°C and an operating pressure of 2.3 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 32:

[0152] Table 32 H2S and CO2 conversion, CH4 selectivity

[0153] H2S conversion, % CO2 conversion, % CH4 selectivity, % 59.6 43.7 88.8

[0154] Example 33

[0155] A 20 wt% 3A-55 wt% 10X molecular sieve catalyst doped with 15 wt% Co-10 wt% Ni was placed in the reaction chamber, the shell 4 was made of quartz glass, and nitrogen was passed for 10 minutes to remove the air in the reactor. The flow rate of the space velocity passed through the bed. The reaction pressure was 2.1 MPa, the reaction temperature was 216°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 54.5 kilovolts, and the frequency was 13 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -53°C and an operating pressure of 3.1 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 31: -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 0.2 MPa, the reaction temperature was 171°C, the plasma power connected to the high voltage electrode and the ground electrode was turned on, the voltage was adjusted to 85.5 kilovolts, and the frequency was 15.5 kilohertz. The methane content in the tail gas was analyzed on-line by chromatography. The tail gas was purified by a cryogenic methanol wash process at an operating temperature of -53°C and an operating pressure of 4.9 MPa. The rest was the same as in Example 1, and the results of the reaction are shown in Table 33:

[0156] Table 33 H2S and CO2 conversion, CH4 selectivity

[0157] H2S conversion, % CO2 conversion, % CH4 selectivity, % 87.7 50.6 77.2

[0158] Example 34

[0159] A 27wt% Y-type-45wt% M-type molecular sieve catalyst doped with 10wt% Co-18wt% Ni was placed in the reaction chamber, the shell 4 was made of glass, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meter, and a mixed gas with a composition of 88vol% H2S-12vol% CO2 was introduced at a rate of 6000 h -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 1.8 MPa, the reaction temperature was 239°C, the plasma power connected to the high voltage electrode and the grounding electrode was turned on, the voltage was adjusted to 44.5 kilovolts, and the frequency was 12.5 kilohertz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by a low-temperature methanol washing method, the operating temperature was -44°C, and the operating pressure was 1.4 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 34:

[0160] Table 34 H2S and CO2 conversion, CH4 selectivity

[0161] H2S conversion, % CO2 conversion, % CH4 selectivity, % 35.4 91.6 89.9

[0162] Example 35

[0163] A 60wt% 3A-type-24wt% Y-type molecular sieve catalyst doped with 15wt% Co-1wt% Ni was placed in the reaction chamber, the shell 4 was made of corundum, and nitrogen was introduced for 10 minutes to remove the air in the reactor. The flow rate was controlled by mass flow meter, and a mixed gas with a composition of 94vol% H2S-6vol% CO2 was introduced at a rate of 6000 h -1 The flow rate of the space velocity passed through the bed. The reaction pressure was 1.7 MPa, the reaction temperature was 159°C, the plasma power connected to the high voltage electrode and the grounding electrode was turned on, the voltage was adjusted to 99.5 kilovolts, and the frequency was 18.5 kilohertz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by a low-temperature methanol washing method, the operating temperature was -58°C, and the operating pressure was 4.6 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 35:

[0164] Table 35 H2S and CO2 conversion, CH4 selectivity

[0165] H2S conversion, % CO2 conversion, % CH4 selectivity, % 76.9 98.8 87.3

[0166] Example 36

[0167] A 5wt% Co-4wt% Ni doped 49wt% M-type-42wt% 3A-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of glass, and nitrogen was passed through for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 76 vol% H2S-24 vol% CO2was passed over the catalyst at 320 h -1 The flow rate was controlled by mass flow meters, and a mixture of 76 vol% H2S-24 vol% CO2was passed over the catalyst at 320 h

[0168] Table 36 H2S and CO2conversion, CH4selectivity

[0169] H2S conversion, % CO2 conversion, % CH4 selectivity, % 58.6 72.9 85.5

[0170] Example 37

[0171] A 2wt% Fe-3wt% Ni doped 30wt% 13X-type-65wt% M-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of quartz glass, and nitrogen was passed through for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 54 vol% H2S-46 vol% CO2was passed over the catalyst at 870 h -1 The flow rate was controlled by mass flow meters, and a mixture of 76 vol% H2S-24 vol% CO2was passed over the catalyst at 320 h

[0172] Table 37 H2S and CO2conversion, CH4selectivity

[0173] H2S conversion, % CO2 conversion, % CH4 selectivity, % 85.2 49.1 77.7

[0174] Example 38

[0175] A 12wt% Fe-7wt% Ni doped 72wt% 10X-type-9wt% Y-type molecular sieve catalyst was placed in the reaction chamber, the housing 4 was made of ceramic, and nitrogen was passed through for 10 minutes to remove air from the reactor. The flow rate was controlled by mass flow meters, and a mixture of 71 vol% H2S-29 vol% CO2was passed over the catalyst at 460 h -1The air velocity flow rate passed through the bed. The reaction pressure was 2.4 MPa, the reaction temperature was 149 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 34.5 kV and the frequency to 23.5 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -64 °C and an operating pressure of 5.6 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 38.

[0176] Table 38 H2S and CO2 conversion rates, CH4 selectivity

[0177] H2S conversion, % CO2 conversion, % CH4 selectivity, % 71.3 68.7 91.4

[0178] Example 39

[0179] A 55wt% 4A-15wt% 5A molecular sieve catalyst doped with 18wt% Fe-12wt% Ni was placed in the reaction chamber. The shell 4 was made of corundum. Nitrogen gas was introduced for 10 minutes to remove air from the reactor. A mixture of 98vol% H2S and 2vol% CO2 was used, controlled by a mass flow meter, to produce the catalyst at a flow rate of 650 h⁻¹. -1 The air velocity flow rate passed through the bed. The reaction pressure was 0.8 MPa, the reaction temperature was 240 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 14.5 kV and the frequency to 26.5 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -54 °C and an operating pressure of 1.9 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 39.

[0180] Table 39 H2S and CO2 conversion rates, CH4 selectivity

[0181] H2S conversion, % CO2 conversion, % CH4 selectivity, % 55.7 42.9 77.0

[0182] Example 40

[0183] A 40wt% 5A-51wt% Y-type molecular sieve catalyst doped with 3.5wt% Cu and 5.5wt% Ni was placed in the reaction chamber. The shell 4 was made of quartz glass. Nitrogen gas was introduced for 10 minutes to remove air from the reactor. A mixture of 65 vol% H2S and 35 vol% CO2 was used, controlled by a mass flow meter, at a flow rate of 1050 h⁻¹. -1 The air velocity flow rate passed through the bed. The reaction pressure was 0.9 MPa, the reaction temperature was 135 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 5.5 kV and the frequency to 10.2 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -50 °C and an operating pressure of 3.0 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 40.

[0184] Table 40 H2S and CO2 conversion rates, CH4 selectivity

[0185] H2S conversion, % CO2 conversion, % CH4 selectivity, % 61.7 78.0 89.2

[0186] Example 41

[0187] A 30wt% 3A-44wt% 5A molecular sieve catalyst doped with 12wt% Cu and 14wt% Ni was placed in the reaction chamber. The shell 4 was made of glass. Nitrogen gas was introduced for 10 minutes to remove air from the reactor. A mixture of 74 vol% H2S and 26 vol% CO2 was introduced at a flow rate controlled by a mass flow meter for 600 h⁻¹. -1 The air velocity flow rate passed through the bed. The reaction pressure was 0.2 MPa, the reaction temperature was 125 °C, and the plasma power supply connected to the high-voltage electrode and the ground electrode was turned on, with the voltage adjusted to 2.5 kV and the frequency to 9.8 kHz. The methane content in the tail gas was analyzed online by chromatography. The tail gas was purified by low-temperature methanol washing at an operating temperature of -45 °C and an operating pressure of 4.5 MPa. The rest was the same as in Example 1, and the reaction results are shown in Table 41.

[0188] Table 41 H2S and CO2 conversion rates, CH4 selectivity

[0189] H2S conversion, % CO2 conversion, % CH4 selectivity, % 43.3 40.1 70.8

[0190] The experimental results above indicate that dielectric barrier discharge combined with sulfides can overcome thermodynamic equilibrium limitations to achieve highly selective conversion of carbon dioxide and hydrogen sulfide mixtures into methane, which is an efficient and effective method for methane production.

Claims

1. A method for producing methane from a mixture of H2S and CO2, characterized in that: Metal-modified molecular sieves are placed in the reaction chamber of a cylindrical reactor. After nitrogen is introduced to remove air from the reactor, a mixture of H2S and CO2 is introduced. The volume percentage of H2S in the mixture is 40-99%, and the volume percentage of CO2 is 1-60%. The flow rate of the mixture is 100-10000 h⁻¹. -1 The reaction pressure is 0.1–3 MPa, the reaction temperature is 120–250℃, and the plasma power supply connected to the high-voltage electrode and the grounding electrode is turned on. The voltage is adjusted to 0.5–100 kV and the frequency is 0.5–30 kHz. After the reaction, the gas is purified by low-temperature methanol washing to obtain pure CH4 gas. The washed-off H2S and CO2 gas are returned to the raw material gas for further reaction. The metal-modified molecular sieve is one or a mixture of two of the following: 3A type molecular sieve, 4A type molecular sieve, 5A type molecular sieve, 10X type molecular sieve, 13X type molecular sieve, 10X type molecular sieve, M type molecular sieve, and Y type molecular sieve. The metal in the metal-modified molecular sieve is one or a mixture of two of the following: Pt, Pd, Rh, Ag, Mn, Zn, Cu, Ni, Co, and Fe.

2. The method for producing methane from a mixture of H2S and CO2 as described in claim 1, characterized in that: During the low-temperature methanol washing purification process, the operating temperature is -29 to -65 ℃, the operating pressure is 1-7.5 MPa, and the purified synthesis gas contains H2S < 0.2 ppm and CO2 < 0.3 vol%.

3. The method for producing methane from a mixture of H2S and CO2 as described in claim 1 or 2, characterized in that: The cylindrical reactor has an air inlet (1), a high-voltage electrode (2), a grounding electrode (3), a shell (4), and an air outlet (5). A columnar conductor is installed on the axis of the shell (4) as the high-voltage electrode (2), and a coil is wound around the outside of the shell (4) as the grounding electrode (3). The inside of the shell (4) is a cylindrical reaction chamber. The upper end of the shell (4) has an air inlet (1), and the lower end of the shell (4) has an air outlet (5). The high-voltage electrode (2) is connected to high voltage through a wire, and the grounding electrode (3) is grounded through a wire.

4. The method for producing methane from a mixture of H2S and CO2 as described in claim 3, characterized in that: The shell (4) is made of glass, quartz glass, ceramic or corundum.

Images