A reaction coupling device and method for sulfur dioxide reduction and methane reforming

Abstract

The application relates to a reaction coupling device and method for sulfur dioxide reduction and methane reforming, which comprises the following steps: mixing primary reaction raw gas with secondary reaction backflow gas, sulfur dioxide contained in the primary reaction raw gas and carbon monoxide, hydrogen and hydrogen sulfide contained in the secondary reaction backflow gas perform primary reaction to generate primary reaction outlet gas containing hydrogen sulfide; mixing the primary reaction outlet gas with secondary reaction raw gas, hydrogen sulfide contained in the primary reaction outlet gas and methane contained in the secondary reaction raw gas perform secondary reaction to generate secondary reaction outlet gas containing carbon monoxide, hydrogen and hydrogen sulfide; and sending part of the secondary reaction outlet gas back as secondary reaction backflow gas to be mixed with the primary reaction raw gas, and the rest of the secondary reaction outlet gas is separated or converted to obtain mixed gas containing carbon monoxide and hydrogen. Compared with the prior art, the application is suitable for by-product utilization in metallurgical and other industrial fields, and is low-temperature and high-efficiency sulfur and synthetic gas coupling production.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy and energy environmental protection technology, and relates to a reaction coupling device and method for sulfur dioxide reduction and methane reforming. Background Technology

[0002] Sulfur dioxide (SO2) is a major pollutant in industries such as metal smelting and coal-fired power generation. It is characterized by its wide distribution and large emissions. While existing dry and wet desulfurization technologies have good SO2 removal efficiency, they suffer from drawbacks such as high water consumption and low by-product utilization rates. Therefore, novel high-value SO2 utilization technologies have become a research hotspot in recent years. SO2 reduction technology aims to convert SO2 into sulfur, which has higher economic value, or to deeply reduce it to hydrogen sulfide (H2S), for use in the purification of heavy metal sulfides and waste acid, thereby achieving its resource utilization.

[0003] Recent studies have shown that sulfur and H2S, the SO2 reduction products, can promote the reforming of methane (CH4) on certain catalysts. However, due to the stability of CH4, the CH4 reforming reaction needs to be carried out at relatively high temperatures (>700℃). Conventional catalysts (Pt, Ru, Fe, Ni, etc.) are prone to carbon deposition and deactivation during the reforming reaction, and sulfur can easily poison them during the reaction, making it difficult for CH4 to directly reduce SO2.

[0004] Patent CN110357043A discloses a method for preparing hydrogen sulfide using high-concentration sulfur dioxide and natural gas, comprising the following steps: First, an appropriate amount of methane reacts with high-concentration sulfur dioxide at a suitable temperature to generate carbon disulfide, hydrogen sulfide, carbon dioxide, and water; the generated products enter a secondary reactor for catalytic hydrolysis of carbon disulfide to convert it into hydrogen sulfide; finally, the remaining carbon disulfide and water are cooled and separated to obtain a mixture of high-concentration hydrogen sulfide and carbon dioxide, and the obtained high-concentration hydrogen sulfide gas is fed into a waste acid treatment device.

[0005] Patent CN111362330A discloses a method for preparing hydrogen sulfide by the stepwise reduction of sulfur dioxide, comprising the following steps: using high-concentration sulfur dioxide gas as raw material, mixing it with a reducing agent, and then entering a sulfur dioxide pre-reducer for catalytic reduction to active elemental sulfur; the hot gas stream exiting the pre-reducer is mixed with natural gas and enters a secondary reducer to react and form a mixture of carbon disulfide, hydrogen sulfide, and carbon dioxide; after mixing with water vapor, the mixture enters a primary hydrolysis reactor for catalytic hydrolysis to hydrogen sulfide gas; the gas stream exiting the primary hydrolysis reactor is divided into two streams, the first stream is returned to the sulfur dioxide pre-reducer for use as a reducing agent; the second remaining gas stream is supplemented with water vapor and then enters a deep hydrolysis reactor for hydrolysis, cooling, and condensation to obtain a high-concentration mixture of hydrogen sulfide and carbon dioxide.

[0006] The above-mentioned patented methods for producing H2S still require temperatures above 600℃, resulting in high energy consumption. Furthermore, the process generates a large amount of CO2 gas that is not effectively utilized. If this CO2 is emitted, it will contribute to the greenhouse effect. Therefore, it is necessary to further explore methods for producing H2S at low temperatures, reducing CO2 emissions, and producing high-value gases. Summary of the Invention

[0007] The purpose of this invention is to overcome at least one of the problems of low sulfur dioxide resource utilization and high energy input in the existing technology, and to provide a reaction coupling device and method for sulfur dioxide reduction and methane reforming. This invention is applicable to the utilization of by-products in metallurgy and other industrial fields, and low-temperature and high-efficiency coupled production of sulfur and syngas.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] One of the technical solutions of the present invention is to provide a reaction coupling method for sulfur dioxide reduction and methane reforming, the method comprising the following steps:

[0010] S1. The primary reaction feed gas is mixed with the secondary reaction reflux gas. The sulfur dioxide contained in the primary reaction feed gas undergoes a primary reaction with the carbon monoxide, hydrogen, and hydrogen sulfide contained in the secondary reaction reflux gas. Under the induction of the mixture of carbon monoxide, hydrogen, and hydrogen sulfide, the sulfur dioxide is rapidly reduced at a relatively low temperature to generate a primary reaction outlet gas containing a high concentration of hydrogen sulfide. The reaction equation for the primary reaction is as follows:

[0011] 2SO2+3CO+3H2+H2S=2H2S+3CO2+H2O+H2S;

[0012] S2. The outlet gas of the first-stage reaction is mixed with the feed gas of the second-stage reaction. The hydrogen sulfide contained in the outlet gas of the first-stage reaction undergoes a second-stage reaction with the methane contained in the feed gas of the second-stage reaction. Under the promotion of hydrogen sulfide, the methane is efficiently reformed at a higher temperature to produce an outlet gas of the second-stage reaction rich in carbon monoxide, hydrogen, and hydrogen sulfide. The reaction equation for the second-stage reaction is as follows:

[0013] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0014] S3. A portion of the outlet gas from the secondary reaction is returned as secondary reaction reflux gas according to demand and mixed with the feed gas from the primary reaction. The remainder is separated or converted by hydrogen sulfide to obtain a mixed gas containing carbon monoxide and hydrogen, which can be used in metallurgical processes as feed gas for metallurgical reduction or in other processes.

[0015] Furthermore, depending on the desired target product, the secondary reaction feed gas in step S2 contains methane, as well as one or more of carbon dioxide, water vapor, and sulfur dioxide. Under the promotion of hydrogen sulfide, efficient reforming of methane is achieved at a higher temperature, followed by dry reforming with carbon dioxide, wet reforming with water vapor, or reduction amplification with sulfur dioxide to further generate hydrogen sulfide. The reaction equations for the dry reforming, wet reforming, and reduction amplification are as follows:

[0016] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0017] CH4 + 2H2O + H2S = 4H2 + CO2 + H2S;

[0018] 3CH4+4SO2+8H2S=3CO2+12H2S+2H2O.

[0019] Furthermore, if the goal is to produce gas from methane reforming, the volume fraction of added carbon dioxide is 10-20%, and the volume fraction of added water vapor is 1-10%. If the goal is to increase sulfur recovery, the volume fraction of added sulfur dioxide is 10-20%.

[0020] Furthermore, the method for converting hydrogen sulfide in step S3 includes the following steps:

[0021] The effluent gas from the secondary reaction is mixed with the feed gas from the tertiary reaction. The hydrogen sulfide in the effluent gas from the secondary reaction and the sulfur dioxide in the feed gas from the tertiary reaction undergo a tertiary Claus reaction, converting hydrogen sulfide at a relatively low temperature. After cooling, the tertiary reaction solid product containing high-quality sulfur is separated. The reaction equation for the tertiary Claus reaction is as follows:

[0022] SO2 + 2H2S = 3S + H2O.

[0023] Furthermore, the three-stage Claus reaction is carried out at an operating temperature of 80-200°C under normal pressure, without the need for an additional catalyst.

[0024] The volume fraction of sulfur dioxide in the third-stage reaction feed gas is 10-50%. The third-stage reaction feed gas (10) is mixed with the second-stage reaction outlet gas (9) at a volume ratio of 1:(1-4). The volume ratio of sulfur dioxide to hydrogen sulfide in the mixed gas is 1:(2-3).

[0025] Furthermore, in step S1, the operating temperature of the first-order reaction is 300-600℃, the pressure is atmospheric pressure to 0.5 MPa, and the gas hourly space velocity is 5000-200000 mL / (h·g).

[0026] The primary reaction feed gas and the secondary reaction reflux gas are mixed in a volume ratio of 1:(0.2-0.5). The volume fraction of sulfur dioxide in the mixed gas is 5-30%, the volume fraction of hydrogen sulfide is 5-30%, and the volume ratio of the sum of carbon monoxide and hydrogen to hydrogen sulfide is (1-3):1.

[0027] The volume fraction of hydrogen sulfide, carbon dioxide, and water vapor in the outlet gas of the first-stage reaction is 10-50% by volume.

[0028] Furthermore, in step S2, the operating temperature of the second-order reaction is 600-900℃, the pressure is atmospheric pressure to 0.5 MPa, and the gas hourly space velocity is 5000-200000 mL / (h·g).

[0029] The outlet gas of the first-stage reaction is mixed with the feed gas of the second-stage reaction at a volume ratio of (0.5-1):1. The volume fraction of hydrogen sulfide in the mixture is 5-30%, the volume fraction of methane is 10-30%, the volume fraction of carbon dioxide is 10-30%, and the volume fraction of water vapor is 1-10%.

[0030] The volume fraction of hydrogen sulfide in the outlet gas of the secondary reaction is 3-20%, the volume fraction of carbon monoxide is 10-40%, and the volume fraction of hydrogen is 10-40%.

[0031] Furthermore, in step S3, the secondary reaction reflux gas accounts for 20-50% of the total volume of the secondary reaction outlet gas.

[0032] One of the technical solutions of the present invention is to provide a reaction coupling device for sulfur dioxide reduction and methane reforming. The method is carried out through the device, which includes a primary reactor and a secondary reactor. The primary reactor is used for the reduction of sulfur dioxide and the mass production of hydrogen sulfide, and the secondary reactor is used for the reforming of methane or the reduction of sulfur dioxide on a larger scale.

[0033] The primary reaction feed gas is mixed with the secondary reaction reflux gas from the outlet of the secondary reactor and then enters the primary reactor. A primary catalytic reaction occurs in the primary reactor to generate the primary reaction outlet gas.

[0034] The gas exiting the primary reaction enters the secondary reactor, where it mixes with the feed gas for the secondary reaction at the inlet of the secondary reactor. A secondary catalytic reaction then occurs within the secondary reactor, generating the gas exiting the secondary reaction.

[0035] A portion of the gas exiting the secondary reactor is sent back to the inlet of the primary reactor as secondary reaction reflux gas.

[0036] Furthermore, the primary reactor is provided with a primary reaction catalyst layer, and the secondary reactor is provided with a secondary reaction catalyst layer. The catalysts filled in the primary and secondary reaction catalyst layers are metal sulfide catalysts. The metals are selected from one or more of cobalt, molybdenum, iron, nickel, copper, and cerium. The catalyst support is selected from one or more of alumina, titanium dioxide, and silicon dioxide.

[0037] This invention utilizes the partial reflux of the reforming reaction outlet gas (carbon monoxide, hydrogen, and hydrogen sulfide) to induce the reduction of sulfur dioxide, promoting the efficient conversion of sulfur dioxide to hydrogen sulfide and achieving a first-stage scale-up of high-concentration hydrogen sulfide. The generated hydrogen sulfide enters the methane reforming reaction unit, utilizing its role in promoting the reforming reaction to achieve a second-stage scale-up of the methane reforming reaction, further producing high-value product gases such as carbon monoxide and hydrogen. Through two-stage or multi-stage enhanced scale-up reactions, the material conversion efficiency and energy utilization rate of the device are significantly improved compared to single-stage reactions, and the reaction products can be flexibly adjusted as needed.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) This invention achieves efficient low-temperature sulfur dioxide catalytic reduction by reflux of carbon monoxide / hydrogen / hydrogen sulfide, and can achieve a sulfur dioxide conversion rate and hydrogen sulfide yield of more than 98% at 400℃.

[0040] (2) This invention utilizes the high concentration of hydrogen sulfide generated by the first-stage amplification to effectively promote the methane reforming reaction, reduce the reforming temperature and correspondingly reduce energy consumption, and achieves a methane conversion rate of more than 70% at 750℃, while solving the problems of catalytic carbon deposition deactivation and sulfur poisoning.

[0041] (3) The present invention couples sulfur dioxide reduction and methane reforming reactions, and realizes the co-production of sulfur and syngas while making high-value resource utilization of sulfur dioxide, a by-product of industrial flue gas in metallurgy and other industrial fields. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the reaction coupling device for sulfur dioxide reduction and methane reforming in an embodiment of the present invention;

[0043] Figure 2 This is a logic diagram of a reaction coupling device for sulfur dioxide reduction and methane reforming in an embodiment of the present invention.

[0044] Explanation of markings in the diagram:

[0045] 1—Primary reaction feed gas, 2—Primary reactor, 3—Primary reaction catalyst layer, 4—Secondary reaction feed gas, 5—Primary reaction outlet gas, 6—Secondary reaction catalyst layer, 7—Secondary reactor, 8—Tertiary reaction solid product, 9—Secondary reaction outlet gas, 10—Tertiary reaction feed gas, 11—Secondary reaction reflux gas;

[0046] 12—Sulfur dioxide feed gas, 13—Methane feed gas, 14—Return gas containing carbon monoxide, hydrogen, and hydrogen sulfide, 15—Intermediate gas containing hydrogen sulfide, 16—Sulfur dioxide introduction gas, 17—Mixed gas containing carbon monoxide and hydrogen, 18—Sulfur products. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0048] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0049] This invention provides a reaction coupling device for sulfur dioxide reduction and methane reforming, such as... Figure 1 As shown, it includes a primary reactor 2 and a secondary reactor 7. The primary reactor 2 is used for the reduction of sulfur dioxide and the mass production of hydrogen sulfide, while the secondary reactor 7 is used for the reforming of methane or the reduction of sulfur dioxide on a larger scale.

[0050] The primary reaction feed gas 1 is mixed with the secondary reaction reflux gas 11 refluxed from the outlet of the secondary reactor 7 and then enters the primary reactor 2. A primary catalytic reaction occurs in the primary reactor 2 to generate the primary reaction outlet gas 5.

[0051] The primary reaction outlet gas 5 is introduced into the secondary reactor 7, where it is mixed with the secondary reaction feed gas 4 at the inlet of the secondary reactor 7. A secondary catalytic reaction occurs in the secondary reactor 7 to generate the secondary reaction outlet gas 9.

[0052] A portion of the gas exiting the secondary reactor 7 is sent back to the inlet of the primary reactor 7 as secondary reaction reflux gas 11.

[0053] like Figure 2As shown, the reaction coupling device for sulfur dioxide reduction and methane reforming is represented by an operational amplifier circuit diagram. This illustrates that the two-stage reactions amplify the chemical reactions, facilitating the understanding of the promoting effects of the two-stage reactions on sulfur dioxide reduction and methane reforming. Sulfur dioxide feed gas 12, methane feed gas 13, and reflux gas 14 containing carbon monoxide, hydrogen, and hydrogen sulfide are mixed and then fed into the first-stage amplifier. Through efficient reduction of sulfur dioxide, an intermediate gas 15 containing hydrogen sulfide (containing a high concentration of hydrogen sulfide) is generated. This intermediate gas then enters the second-stage amplifier, where a reforming reaction occurs under the promoting effect of the high concentration of hydrogen sulfide, producing a product gas containing a high concentration of syngas. A portion of this product gas is refluxed back to the first amplifier as reflux gas 14 containing carbon monoxide, hydrogen, and hydrogen sulfide, and mixed with sulfur dioxide feed gas 12 and methane feed gas 13. Another portion is mixed with sulfur dioxide inlet gas 16 to produce sulfur product 18. The remaining mixed gas 17 containing carbon monoxide and hydrogen is further purified.

[0054] The primary reactor 2 is equipped with a primary reaction catalyst layer 3, and the secondary reactor 7 is equipped with a secondary reaction catalyst layer 6. The catalysts filled in the primary reaction catalyst layer 3 and the secondary reaction catalyst layer 6 are both metal sulfide catalysts. The metal is selected from one or more of cobalt (Co), molybdenum (Mo), iron (Fe), nickel (Ni), copper (Cu), and cerium (Ce). The catalyst support is selected from one or more of alumina (Al2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2).

[0055] This invention provides a reaction coupling method for sulfur dioxide reduction and methane reforming, using the aforementioned apparatus for the reaction, with the specific steps as follows:

[0056] S1. The primary reaction feed gas 1 is mixed with the secondary reaction reflux gas 11. The sulfur dioxide (SO2) contained in the primary reaction feed gas 1 undergoes a primary reaction with the carbon monoxide (CO), hydrogen (H2), and hydrogen sulfide (H2S) contained in the secondary reaction reflux gas 11. Under the induction of the CO, H2, and H2S mixture, SO2 is rapidly reduced at a relatively low temperature to generate the primary reaction outlet gas 5 containing a high concentration of H2S. The reaction equation for the primary reaction is as follows:

[0057] 2SO2+3CO+3H2+H2S=2H2S+3CO2+H2O+H2S;

[0058] The operating temperature for first-order reactions is 300-600℃, the pressure is atmospheric pressure to 0.5 MPa, and the gas hourly space velocity is 5000-200000 mL / (h·g).

[0059] The primary reaction feed gas 1 and the secondary reaction reflux gas 11 are mixed at a volume ratio of 1:(0.2-0.5). The volume fraction of SO2 in the mixed gas is 5-30%, the volume fraction of H2S is 5-30%, and the volume ratio of the sum of CO and H2 to H2S is (1-3):1.

[0060] The volume fraction of H2S in the outlet gas 5 of the first-stage reaction is 10-50%, the volume fraction of carbon dioxide (CO2) is 5-20%, and the volume fraction of water vapor (H2O) is 5-20%.

[0061] S2. The first-stage reaction outlet gas 5 is mixed with the second-stage reaction feed gas 4. The H2S contained in the first-stage reaction outlet gas 5 undergoes a second-stage reaction with the methane (CH4) contained in the second-stage reaction feed gas 4. Under the promotion of H2S, the CH4 is efficiently reformed at a higher temperature to produce a second-stage reaction outlet gas 9 rich in CO, H2, and H2S. The reaction equation for the second-stage reaction is as follows:

[0062] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0063] Depending on the desired target product, the secondary reaction feedstock gas 4 contains CH4, as well as one or more of CO2, H2O, and SO2. With the promotion of H2S, CH4 undergoes efficient reforming at a higher temperature, followed by dry reforming with CO2, wet reforming with H2O, or reduction amplification with SO2 to further generate H2S. The reaction equations for dry reforming, wet reforming, and reduction amplification are as follows:

[0064] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0065] CH4 + 2H2O + H2S = 4H2 + CO2 + H2S;

[0066] 3CH4+4SO2+8H2S=3CO2+12H2S+2H2O;

[0067] If the goal is to produce gas through CH4 reforming, the volume fraction of CO2 added should be 10-20%, and the volume fraction of H2O added should be 1-10%. If the main goal is to increase sulfur recovery, the volume fraction of SO2 added should be 10-20%.

[0068] The operating temperature for the second-order reaction is 600-900℃, the pressure is atmospheric pressure to 0.5 MPa, and the gas hourly space velocity is 5000-200000 mL / (h·g).

[0069] The first-stage reaction outlet gas 5 is mixed with the second-stage reaction feed gas 4 in a volume ratio of (0.5-1):1. The volume fraction of H2S in the mixed gas is 5-30%, the volume fraction of CH4 is 10-30%, the volume fraction of CO2 is 10-30%, and the volume fraction of H2O is 1-10%.

[0070] The volume fraction of H2S in the outlet gas 9 of the secondary reaction is 3-20%, the volume fraction of CO is 10-40%, and the volume fraction of H2 is 10-40%.

[0071] S3. Part of the secondary reaction outlet gas 9 is sent back as secondary reaction reflux gas 11 according to the required amount and mixed with the primary reaction feed gas 1. The remainder is separated or converted by H2S to obtain a mixed gas containing CO and H2, which can be used in metallurgical processes as feed gas for metallurgical reduction, or used in other processes.

[0072] The secondary reaction reflux gas 11 accounts for 20-50% of the total volume of the secondary reaction outlet gas.

[0073] This invention also provides a reaction coupling method for sulfur dioxide reduction and methane reforming, which, while using the above-mentioned apparatus for the reaction, adds a three-stage reactor for hydrogen sulfide conversion. The specific steps are as follows:

[0074] The secondary reaction outlet gas 9 is mixed with the tertiary reaction feed gas 10. The H2S contained in the secondary reaction outlet gas 9 undergoes a tertiary Claus reaction with the SO2 contained in the tertiary reaction feed gas 10, achieving the conversion of H2S at a relatively low temperature. After cooling, the tertiary reaction solid product 8 containing high-quality sulfur is separated. The reaction equation for the tertiary Claus reaction is as follows:

[0075] SO2 + 2H2S = 3S + H2O;

[0076] The tertiary Claus reaction operates at temperatures of 80-200°C under normal pressure, requiring no additional catalyst.

[0077] The volume fraction of SO2 in the third-stage reaction feed gas 10 is 10-50%. The third-stage reaction feed gas 10 is mixed with the second-stage reaction outlet gas 9 at a volume ratio of 1:(1-4). The volume ratio of SO2 to H2S in the mixed gas is 1:(2-3).

[0078] Example 1:

[0079] A reaction coupling device and method for sulfur dioxide reduction and methane reforming are experimentally verified through H2S / H2 / CO co-production via syngas (H2 and CO) and H2S reflux. The specific steps are as follows:

[0080] In this embodiment, a two-stage series tubular furnace reactor was established; two quartz tubes with a length of 500 mm and an inner diameter of 8 mm were used as reaction vessels, and each was filled with 0.2 g of 50±10 mesh CoMo / Al2O3 catalyst that had undergone pre-sulfurization treatment.

[0081] First, CO:H2:CH4:SO2:N2 is introduced into primary reactor 2 at a volume ratio of 1:1:0.75:1:5, with a gas hourly space velocity of 18000 mL / (h·g). The reaction is carried out at one atmosphere and the temperature is maintained at 700℃. Under these conditions, SO2 reduction occurs in primary reactor 2, and the main product is H2S. The volume fraction of H2S in the outlet gas 5 of primary reactor is 15%, the volume fraction of CO2 is 10%, and the volume fraction of H2O is 5%. At this point, the SO2 conversion rate is 99%, and the H2S selectivity is 98%.

[0082] Next, the outlet gas 5 from the primary reactor was mixed with CH4, CO2, and SO2 at a volume ratio of 3:1:1:1.25 and introduced into the secondary reactor 7. The gas hourly space velocity was 36,000 mL / (h·g), and the reaction was carried out at one atmosphere while maintaining the temperature at 750℃. Under these conditions, CH4 and CO2 underwent a dry reforming reaction with a conversion rate of 60%. The volume fractions of H2 and CO in the outlet gas 9 of the secondary reaction were 36% and 30%, respectively, with an H2 / CO volume ratio of 1.2. The volume fraction of H2S was 16%, and the H2S selectivity was 96%. This indicates that SO2 reduction and CH4 reforming reactions occurred simultaneously in the secondary reactor 7, and the reforming reaction included both steam reforming and dry reforming. Therefore, the H2 / CO volume ratio was greater than 1. The phenomenon shows that H2S can effectively promote the occurrence of CH4 steam reforming and dry reforming.

[0083] After 1 hour of stable operation, part of the outlet gas 9 from the secondary reactor was refluxed to the inlet of the primary reactor 2. The primary reaction feed gas 1 and the secondary reaction reflux gas 11 were mixed at a volume ratio of 1:0.3, and the supply of H2 and CO to the primary reactor 2 was stopped. At this point, the CO:H2:CH4:SO2:H2S:N2 ratio in the mixed gas was 1:1:0.75:1:2:5. The temperature of the primary reactor 2 was reduced to 600℃. At this point, the SO2 conversion rate and H2S yield of the primary reactor 2 were 99% and 98%, respectively, while the secondary reactor 7 maintained a CH4 conversion rate of 60%, and the volume fractions of H2 and CO were 24% and 20%, respectively, with the H2 / CO volume ratio remaining at 1.2. The reaction maintained stable operation for 24 hours, successfully obtaining the H2S / H2 / CO gaseous product composition. This example verifies the promoting effect of two-stage scale-up on SO2 reduction and CH4 reforming reactions, respectively.

[0084] Example 2:

[0085] A reaction coupling device and method for sulfur dioxide reduction and methane reforming, verified experimentally by H2S / H2 / CO co-production via syngas and H2S reflux, with the specific steps as follows:

[0086] In this embodiment, a two-stage series tubular furnace reactor was established; two quartz tubes with a length of 500 mm and an inner diameter of 8 mm were used as reaction vessels, and each was filled with 0.2 g of 50±10 mesh CoMo / Al2O3 catalyst that had undergone pre-sulfurization treatment.

[0087] First, CO:H2:SO2:N2 is introduced into primary reactor 2 at a volume ratio of 1.5:1.5:1:4, with a gas hourly space velocity of 18000 mL / (h·g). The reaction is carried out at one atmosphere and the temperature is maintained at 600℃. Under these conditions, SO2 reduction occurs in primary reactor 2, and the product ratio of H2S:H2O:CO2:N2 is 1:1.5:1.5:4. At this point, the SO2 conversion rate is 98% and the H2S selectivity is 99%.

[0088] Next, the outlet gas 5 from the primary reactor was mixed with CH4 and CO2 at a volume ratio of 3:1:1 and fed into the secondary reactor 7. The gas hourly space velocity was 18000 mL / (h·g), and the reaction was carried out at one atmosphere while maintaining the temperature at 750℃. Under these conditions, CH4 and CO2 underwent a dry reforming reaction with a conversion rate of 75%. The volume fractions of H2, CO, and H2S in the outlet gas 9 from the secondary reaction were 40%, 32%, and 12%, respectively, with an H2 / CO volume ratio of 0.8. This indicates that H2S can effectively promote the CH4 reforming reaction, thereby achieving the production of H2 and CO.

[0089] After 1 hour of stable operation, part of the outlet gas 9 from the secondary reactor was refluxed to the inlet of the primary reactor 2. The primary reaction feed gas 1 and the secondary reaction reflux gas 11 were mixed at a volume ratio of 1:0.3, and the supply of H2 and CO to the primary reactor 2 was stopped. At this time, the CO:H2:SO2:H2S:N2 ratio in the mixed gas was 1.5:1.5:1:2:2. The temperature of the primary reactor 2 was reduced to 400℃. At this time, the primary reactor 2 still maintained a SO2 conversion rate of 98% and an H2S yield of 99%, and the secondary reactor 7 still maintained a CH4 conversion rate of 75%. The volume fractions of H2 and CO were 24% and 30%, respectively, and the H2 / CO volume ratio remained at 0.8. The reaction maintained stable operation for 24 hours and successfully obtained the H2S / H2 / CO gaseous product composition. This shows that the reflux of H2S / H2 / CO gas effectively reduced the SO2 reduction temperature, keeping it at 400℃, while generating a high concentration of H2S to enter the secondary scale-up, promoting the CH4 reforming reaction. This embodiment verifies the promoting effect of two-stage amplification on SO2 reduction and CH4 reforming reactions, respectively.

[0090] Example 3:

[0091] An industrial example of a reaction coupling device and method for sulfur dioxide reduction and methane reforming, using syngas (H2 and CO) and H2S reflux for sulfur / H2 / CO co-production, is described below:

[0092] In this embodiment, a three-stage series reactor system was established; the inner diameter of a single reactor is 10m and the height is 50m; each reactor is filled with 10kg of pre-sulfurized CoMo / Al2O3 catalyst with an average particle size of 100mm.

[0093] The temperature of the primary reactor is maintained at 400℃, the secondary reactor at 800℃, and the tertiary reactor at 150℃, with the reaction proceeding at one atmosphere. Simultaneously, 30% of the gas exiting the secondary reactor is refluxed to the inlet of the primary reactor. Additionally, industrial flue gas containing 20% ​​SO2 is introduced at a gas hourly space velocity (GHSV) of 36,000 mL / (h·g), and the reaction operates at one atmosphere. After the reaction starts, SO2 reduction occurs in the primary reactor, with H2S as the main product. The volume fraction of H2S in the primary reactor outlet gas (5) is 20%. At this point, both the SO2 conversion rate and the H2S selectivity reach 99%.

[0094] The gas generated in the primary reactor enters the secondary reactor, along with a gas containing 20% ​​CH4 and 20% CO2. Under the promotion of H2S, a dry reforming reaction occurs in the secondary reactor. At this time, the CH4 conversion rate is 90%, the CO2 conversion rate is 95%, and the H2 / CO volume ratio is 0.8.

[0095] The gas exiting the secondary reactor is mixed with industrial flue gas containing 20% ​​SO2 and then enters the tertiary reactor. Under these conditions, SO2 reacts with H2S in the gas exiting the secondary reactor via a Claus reaction to produce solid sulfur, with an H2S conversion rate of 99%. The H2 / CO volume fractions in the gaseous products are 16% and 18%, respectively. Through separation and purification, high-purity syngas can be obtained. This embodiment achieves the co-production of solid sulfur and gaseous syngas on an industrial scale.

[0096] Example 4:

[0097] A reaction coupling apparatus and method for sulfur dioxide reduction and methane reforming, including a laboratory example of sulfur / H2 / CO co-production via syngas (H2 and CO) and H2S reflux, with the specific steps as follows:

[0098] In this embodiment, a three-stage series tubular furnace reactor was established; three quartz tubes with a length of 500 mm and an inner diameter of 8 mm were used as reaction vessels, and 0.2 g of pre-sulfurized 50±10 mesh CoMo / Al2O3 catalyst was loaded into the first two tubes respectively.

[0099] S1. The primary reaction feed gas 1 is mixed with the secondary reaction reflux gas 11. The SO2 contained in the primary reaction feed gas 1 undergoes a primary reaction with the CO, H2, and H2S contained in the secondary reaction reflux gas 11. Under the induction of the CO, H2, and H2S mixture, SO2 is rapidly reduced at a lower temperature to generate the primary reaction outlet gas 5 containing a high concentration of H2S. The reaction equation for the primary reaction is as follows:

[0100] 2SO2+3CO+3H2+H2S=2H2S+3CO2+H2O+H2S;

[0101] The first-order reaction was conducted at an operating temperature of 400℃, a pressure of 0.3 MPa, and a gas hourly space velocity of 10000 mL / (h·g).

[0102] The primary reaction feed gas 1 and the secondary reaction reflux gas 11 are mixed at a volume ratio of 1:0.4. The volume fraction of SO2 in the mixed gas is 20%, the volume fraction of H2S is 15%, and the volume ratio of the sum of CO and H2 to H2S is 2:1.

[0103] The volume fraction of H2S in the outlet gas 5 of the first-stage reaction is 40%, the volume fraction of CO2 is 10%, and the volume fraction of H2O is 10%. At this time, the SO2 conversion rate is 99% and the H2S selectivity is 99%.

[0104] S2. The first-stage reaction outlet gas 5 is mixed with the second-stage reaction feed gas 4. The H2S contained in the first-stage reaction outlet gas 5 undergoes a second-stage reaction with the CH4 contained in the second-stage reaction feed gas 4. Under the promotion of H2S, the CH4 is efficiently reformed at a higher temperature to generate a second-stage reaction outlet gas 9 rich in CO, H2, and H2S. The reaction equation for the second-stage reaction is as follows:

[0105] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0106] Depending on the desired target product, the secondary reaction feedstock gas 4 contains CH4, as well as one or more of CO2, H2O, and SO2. With the promotion of H2S, CH4 undergoes efficient reforming at a higher temperature, followed by dry reforming with CO2, wet reforming with H2O, or reduction amplification with SO2 to further generate H2S. The reaction equations for dry reforming, wet reforming, and reduction amplification are as follows:

[0107] CH4 + CO2 + H2S = 2H2 + 2CO + H2S;

[0108] CH4 + 2H2O + H2S = 4H2 + CO2 + H2S;

[0109] 3CH4+4SO2+8H2S=3CO2+12H2S+2H2O;

[0110] The volume fraction of CO2 added is 10%, the volume fraction of H2O added is 5%, and the volume fraction of SO2 added is 10%.

[0111] The second-order reaction was operated at a temperature of 750℃, a pressure of 0.3 MPa, and a gas hourly space velocity of 10000 mL / (h·g).

[0112] The outlet gas 5 of the first-stage reaction is mixed with the feed gas 4 of the second-stage reaction at a volume ratio of 0.8:1. The volume fraction of H2S in the mixed gas is 20%, the volume fraction of CH4 is 15%, the volume fraction of CO2 is 15%, and the volume fraction of H2O is 8%.

[0113] The volume fraction of H2S in the outlet gas 9 of the secondary reaction is 16%, the volume fraction of CO is 30%, and the volume fraction of H2 is 30%. At this time, the CH4 conversion rate is 76%, the H2S selectivity is 97%, and the H2 / CO volume ratio is 0.9.

[0114] S3. Part of the secondary reaction outlet gas 9 is sent back as secondary reaction reflux gas 11 according to the required amount and mixed with the primary reaction feed gas 1. The remainder is separated or converted by H2S to obtain a mixed gas containing CO and H2, which can be used in metallurgical processes as feed gas for metallurgical reduction, or used in other processes.

[0115] The secondary reaction reflux gas 11 accounts for 35% of the total volume of the secondary reaction outlet gas.

[0116] The specific steps for H2S conversion are as follows:

[0117] The secondary reaction outlet gas 9 is mixed with the tertiary reaction feed gas 10. The H2S contained in the secondary reaction outlet gas 9 undergoes a tertiary Claus reaction with the SO2 contained in the tertiary reaction feed gas 10, achieving the conversion of H2S at a relatively low temperature. After cooling, the tertiary reaction solid product 8 containing high-quality sulfur is separated. The reaction equation for the tertiary Claus reaction is as follows:

[0118] SO2 + 2H2S = 3S + H2O;

[0119] The tertiary Claus reaction operates at 100°C under normal pressure and requires no additional catalyst.

[0120] The volume fraction of SO2 in the feed gas 10 of the third-stage reaction is 30%. The feed gas 10 of the third-stage reaction is mixed with the outlet gas 9 of the second-stage reaction at a volume ratio of 1:4. The volume ratio of SO2 to H2S in the mixed gas is 1:2. At this time, the H2S conversion rate is 99% and the H2 / CO volume ratio is 0.96.

[0121] Comparative example:

[0122] A reaction apparatus and method for sulfur dioxide reduction and methane reforming, the specific steps of which are as follows:

[0123] In this embodiment, a separate reaction device for SO2 reduction and CH4 reforming was established; two quartz tubes with a length of 500 mm and an inner diameter of 8 mm were used as reaction vessels, and each was filled with 0.2 g of 50±10 mesh CoMo / Al2O3 catalyst that had been pre-sulfurized.

[0124] First, CH4:SO2:N2 is introduced into the SO2 reduction apparatus in a volume ratio of 3:4:5, with a gas hourly space velocity of 18000 mL / (h·g). The reaction is carried out at one atmosphere and the temperature is maintained at 800℃. Under these conditions, SO2 reduction occurs in the reactor, and the main product is H2S. The volume fraction of H2S in the reactor outlet gas is 20%, the CH4 conversion rate is 70%, and the H2S conversion rate is 90%.

[0125] Then, CH4:CO2:N2 was introduced into the CH4 reforming unit at a volume ratio of 1:1:3, with a gas hourly space velocity of 18000 mL / (h·g). The reaction was carried out at one atmosphere and the temperature was maintained at 800℃. Under these conditions, a dry reforming reaction of CH4 occurred in the reactor, and the main products were H2 and CO. The conversion rates of CH4 and CO2 in the reactor outlet gas were 10% and 15%, respectively, and the volume fractions of H2 and CO were 2% and 4%, respectively.

[0126] Comparative analysis revealed that the conversion rate and selectivity of the embodiment were superior to those of the comparative example, and it could obtain product gas with high CO, H2, and H2S content. Furthermore, H2S could be converted into sulfur products, and syngas products could be separated.

[0127] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A reaction coupling method for sulfur dioxide reduction and methane reforming, characterized in that, The method includes the following steps: S1. Mix the primary reaction feed gas (1) with the secondary reaction reflux gas (11). The sulfur dioxide contained in the primary reaction feed gas (1) and the carbon monoxide, hydrogen and hydrogen sulfide contained in the secondary reaction reflux gas (11) undergo a primary reaction. Under the induction of the mixed gas of carbon monoxide, hydrogen and hydrogen sulfide, the sulfur dioxide is reduced to generate the primary reaction outlet gas (5) containing hydrogen sulfide, carbon dioxide and water vapor. S2. Mix the first-stage reaction outlet gas (5) with the second-stage reaction feed gas (4). The hydrogen sulfide and carbon dioxide contained in the first-stage reaction outlet gas (5) and the methane contained in the second-stage reaction feed gas (4) undergo a second-stage reaction. Under the promotion of hydrogen sulfide, the methane is reformed to generate a second-stage reaction outlet gas (9) containing carbon monoxide, hydrogen and hydrogen sulfide. S3. Part of the secondary reaction outlet gas (9) is sent back as secondary reaction reflux gas (11) and mixed with the primary reaction feed gas (1). The remainder is separated or converted by hydrogen sulfide to obtain a mixed gas containing carbon monoxide and hydrogen.

2. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 1, characterized in that, In step S2, the secondary reaction feed gas (4) contains methane, as well as one or more of carbon dioxide, water vapor, and sulfur dioxide. Under the promotion of hydrogen sulfide, dry reforming between methane and carbon dioxide, wet reforming between methane and water vapor, and reduction amplification between methane and sulfur dioxide are achieved to further generate one or more of hydrogen sulfide.

3. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 2, characterized in that, If the goal of step S2 is to reform methane into gas, the volume fraction of carbon dioxide added is 10-20%, and the volume fraction of water vapor added is 1-10%. If the goal is to increase sulfur recovery, the volume fraction of sulfur dioxide added is 10-20%.

4. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 1, characterized in that, The hydrogen sulfide conversion method in step S3 includes the following steps: The secondary reaction outlet gas (9) is mixed with the tertiary reaction feed gas (10). The hydrogen sulfide contained in the secondary reaction outlet gas (9) and the sulfur dioxide contained in the tertiary reaction feed gas (10) undergo a tertiary Claus reaction to achieve the conversion of hydrogen sulfide and generate a tertiary reaction solid product (8) containing high-quality sulfur.

5. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 4, characterized in that, The operating temperature for the three-stage Claus reaction is 80-200 °C. The volume fraction of sulfur dioxide in the third-stage reaction feed gas (10) is 10-50%. The third-stage reaction feed gas (10) is mixed with the second-stage reaction outlet gas (9) at a volume ratio of 1:(1-4). The volume ratio of sulfur dioxide to hydrogen sulfide in the mixed gas is 1:(2-3).

6. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 1, characterized in that, In step S1, the first-order reaction is operated at a temperature of 300-600 °C, a pressure of atmospheric pressure to 0.5 MPa, and a gas hourly space velocity of 5000-200000 mL / (h·g). The primary reaction feed gas (1) and the secondary reaction reflux gas (11) are mixed in a volume ratio of 1:(0.2-0.5). The volume fraction of sulfur dioxide in the mixed gas is 5-30%, the volume fraction of hydrogen sulfide is 5-30%, and the volume ratio of the sum of carbon monoxide and hydrogen to hydrogen sulfide is (1-3):

1. The volume fraction of hydrogen sulfide in the first-stage reaction outlet gas (5) is 10-50%, the volume fraction of carbon dioxide is 5-20%, and the volume fraction of water vapor is 5-20%.

7. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 1, characterized in that, In step S2, the operating temperature for the second-order reaction is 600-900 °C, the pressure is atmospheric pressure to 0.5 MPa, and the gas hourly space velocity is 5000-200000 mL / (h·g). The primary reaction outlet gas (5) is mixed with the secondary reaction feed gas (4) in a volume ratio of (0.5-1):

1. The volume fraction of hydrogen sulfide in the mixture is 5-30%, the volume fraction of methane is 10-30%, the volume fraction of carbon dioxide is 10-30%, and the volume fraction of water vapor is 1-10%. The volume fraction of hydrogen sulfide in the outlet gas (9) of the secondary reaction is 3-20%, the volume fraction of carbon monoxide is 10-40%, and the volume fraction of hydrogen is 10-40%.

8. The reaction coupling method for sulfur dioxide reduction and methane reforming according to claim 1, characterized in that, In step S3, the secondary reaction reflux gas (11) accounts for 20-50% of the total volume of the secondary reaction outlet gas (9).

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