Sulfur preparation method

Abstract

The invention relates to the technical field of sulfur recovery, in particular to a preparation method of sulfur, which is characterized in that after a catalyst is inactivated, at least one alternate regeneration step and production step are carried out; in the regeneration step, first Claus tail gas and a first oxygen-containing raw material are introduced into a selective oxidation reactor for catalyst regeneration, and the oxygen volume concentration in a gas phase at an outlet of the reactor during regeneration is not less than 5%; the production method comprises the following steps: introducing second Claus tail gas and a second oxygen-containing raw material into a selective oxidation reactor for catalytic reaction, wherein the oxygen volume concentration in a gas phase at an outlet of the reactor is not more than 2% during the reaction. According to the method, efficient regeneration of the catalyst can be achieved, the service life is prolonged, the regeneration process is simple and environmentally friendly, secondary pollution is avoided, long-time operation of the device is guaranteed, and efficient sulfur production is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur recovery, and in particular to a method for preparing sulfur. Background Art

[0002] The core technology of the Super Claus process is the use of advanced H2S selective oxidation catalysts in the reaction section. In recent years, with the vigorous development of coal chemical industry, my country's H2S selective oxidation catalysts have developed rapidly. The new selective oxidation catalysts mainly use non-toxic and harmless iron oxide as the active component, and add corresponding promoters, so that the catalyst has high activity. However, in the application process of the selective oxidation catalyst, as the use time increases, due to improper operation of the device and other reasons, the catalyst becomes deactivated before reaching the service life, and the activity decreases significantly. On the one hand, it affects the normal sulfur recovery rate of the device, and on the other hand, it causes the flue gas SO2 emissions of the device to seriously exceed the standard, resulting in the device being unable to operate normally.

[0003] CN 112337501 A discloses a method for preparing a sulfurized regenerative hydrogenation catalyst, comprising: firstly wetting the carbon-deposited deactivated hydrogenation catalyst with an oxygen-containing organic solvent, then performing a mild sulfur-burning and carbon-burning treatment, and after cooling, vacuum impregnating the catalyst with a water-soluble sulfur-containing composite solution, and obtaining the sulfurized regenerative hydrogenation catalyst after heat treatment.

[0004] CN 112076804A discloses a method for regenerating a heavy distillate oil hydroprocessing catalyst, wherein the regenerated catalyst is placed in a solution containing an inorganic auxiliary agent and an organic chelating ligand auxiliary agent, and is impregnated under acoustic field conditions; the impregnated sample is dried at room temperature; and then an activated catalyst is obtained by two-step heat treatment. The above invention is mainly used for the regeneration of hydrogenation catalysts, and the operation process is relatively complicated, and the catalyst cannot be regenerated online. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that due to improper operation of the Claus process device, the catalyst is deactivated before reaching its service life, and the activity decreases significantly, which affects the normal sulfur recovery rate of the device on the one hand, and causes the flue gas SO2 emission of the device to seriously exceed the standard on the other hand, resulting in the device being unable to operate normally. A sulfur preparation method is provided, which can regenerate the catalyst online, the regeneration process is simple and easy, can reduce the frequency of catalyst replacement in the device, reduce the operating cost of the device, and has significant economic and social benefits.

[0006] In order to achieve the above object, the present invention provides a method for preparing sulfur, wherein after the catalyst is deactivated, at least one alternating regeneration step and production step is performed;

[0007] The regeneration step comprises introducing the first Claus tail gas and the first oxygen-containing feedstock into a selective oxidation reactor to regenerate the catalyst, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not less than 5% during regeneration;

[0008] The production step comprises introducing the second Claus tail gas and the second oxygen-containing raw material into a selective oxidation reactor for catalytic reaction, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not greater than 2% during the reaction.

[0009] Through the above technical solution, the present invention has the following advantages:

[0010] The method of the present invention can realize efficient regeneration of the catalyst and extend the service life. The regeneration process is simple, environmentally friendly and free of secondary pollution, thus ensuring long-term operation of the device and efficient production of sulfur. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a preferred device and flow chart for preparing sulfur in the present invention.

[0012] Description of Reference Numerals

[0013] 1. Reactor; 7. Secondary heater;

[0014] 2. Waste heat boiler; 8. Secondary reactor;

[0015] 3. First stage sulfur condenser; 9. Third stage sulfur condenser;

[0016] 4. First-stage heater; 10. Third-stage heater;

[0017] 5. Primary reactor; 11. Tertiary reactor;

[0018] 6. Secondary sulfur condenser; 12. Fourth-stage sulfur condenser;

[0019] 13. Four-stage heater; 16. Incinerator;

[0020] 14. Selective oxidation reactor; 17. Alkali washing tower;

[0021] 15. Five-stage sulfur condenser; 18. Chimney. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] The present invention provides a method for preparing sulfur, wherein after the catalyst is deactivated, at least one alternating regeneration step and production step is performed;

[0024] The regeneration step comprises introducing the first Claus tail gas and the first oxygen-containing feedstock into a selective oxidation reactor to regenerate the catalyst, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not less than 5% during regeneration;

[0025] The production step comprises introducing the second Claus tail gas and the second oxygen-containing raw material into a selective oxidation reactor for catalytic reaction, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not greater than 2% during the reaction.

[0026] The method of the present invention can realize efficient regeneration of the catalyst and extend the service life. The regeneration process is simple, environmentally friendly and free of secondary pollution, thus ensuring long-term operation of the device and efficient production of sulfur.

[0027] According to a preferred embodiment of the present invention, the H2S concentration in the first Claus tail gas is 0.3-1%, and the SO2 concentration is ≯0.04%. By adopting the above preferred solution, the sulfur production efficiency can be further improved.

[0028] According to a preferred embodiment of the present invention, the H2S concentration in the second Claus tail gas is 0.3-1%.

[0029] According to a preferred embodiment of the present invention, the inlet temperature of the selective oxidation reactor during the catalyst regeneration is higher than the inlet temperature of the selective oxidation reactor during the catalytic reaction, preferably 5-40° C. higher, more preferably 5-20° C. higher, and more preferably 10-15° C. higher. By adopting the above preferred scheme, the sulfur production efficiency can be further improved.

[0030] In the present invention, as long as the oxygen volume concentration in the gas phase at the reactor outlet during regeneration is within the aforementioned range of the present application, according to a preferred embodiment of the present invention, the oxygen volume concentration in the gas phase at the reactor outlet during regeneration is 5-10%. By adopting the aforementioned preferred scheme, the sulfur production efficiency can be further improved.

[0031] In the present invention, as long as the oxygen volume concentration in the gas phase at the reactor outlet during the reaction is within the aforementioned range of the present application, according to a preferred embodiment of the present invention, the oxygen volume concentration in the gas phase at the reactor outlet during the reaction is 0.5-2%. By adopting the aforementioned preferred scheme, the sulfur production efficiency can be further improved.

[0032] According to a preferred embodiment of the present invention, the volume concentration of oxygen in the first oxygen-containing raw material is above 10%, and other gases except oxygen include inert gases, for example, at least one of nitrogen, argon and helium.

[0033] According to a preferred embodiment of the present invention, the volume concentration of oxygen in the second oxygen-containing raw material is 5-21%.

[0034] According to a preferred embodiment of the present invention, the first oxygen-containing raw material and the second oxygen-containing raw material may be air.

[0035] According to a preferred embodiment of the present invention, the catalyst regeneration conditions include: the volume ratio of the first Claus tail gas to the first oxygen-containing feedstock is 10: 1-5: 1, preferably 6: 1-8: 1. By adopting the above preferred solution, the catalyst regeneration efficiency can be further improved, and the sulfur production efficiency can be improved.

[0036] According to a preferred embodiment of the present invention, the catalyst regeneration conditions include: the inlet temperature of the selective oxidation reactor is 180-250°C, preferably 200-240°C.

[0037] According to a preferred embodiment of the present invention, the conditions for catalyst regeneration include: a regeneration temperature of 180-260°C, preferably 200-250°C.

[0038] According to a preferred embodiment of the present invention, the conditions for regenerating the catalyst include: the regeneration time is 10-72h, preferably 24-60h.

[0039] According to a preferred embodiment of the present invention, the conditions for the catalytic reaction include: the volume ratio of the second Claus tail gas to the second oxygen-containing feedstock is 20:1-5:1, preferably 15:1-7:1. By adopting the above preferred solution, the sulfur production efficiency can be further improved.

[0040] According to a preferred embodiment of the present invention, the conditions for the catalytic reaction include: selecting the inlet temperature of the oxidation reactor to be 180-230°C, preferably 200-220°C.

[0041] According to a preferred embodiment of the present invention, the conditions of the catalytic reaction include: the reaction temperature is 170-240°C, preferably 200-240°C.

[0042] According to a preferred embodiment of the present invention, the conditions of the catalytic reaction include: the reaction time is 8-72h, preferably 24-60h.

[0043] According to a preferred embodiment of the present invention, after the catalytic reaction is completed, the inlet temperature of the selective oxidation reactor is lowered to 170-200°C, preferably 180-190°C; during regeneration, the inlet temperature of the reactor is increased to the regeneration temperature at a rate of 10-20°C / h; after regeneration, the inlet temperature of the selective oxidation reactor is lowered to the reaction temperature. By adopting the above preferred scheme, the catalyst regeneration efficiency can be further improved, and the sulfur production efficiency can be improved.

[0044] According to a preferred embodiment of the present invention, the regenerated gas phase is sent to an incinerator for incineration and then washed in an alkali washing tower before being discharged.

[0045] In the present invention, the active component of the catalyst in the selective oxidation reactor may be a conventional hydrogen sulfide selective oxidation sulfur production catalyst in the art, and the active component of the catalyst in the selective oxidation reactor comprises iron oxide.

[0046] In the prior art, there is a situation where the catalyst in the selective oxidation reactor is sulfided due to insufficient oxygen, and loses its catalytic activity, resulting in excessively high concentrations of SO2 and H2S in the tail gas. The main active component of the catalyst in the selective oxidation reactor is Fe2O3. When the amount of oxygen entering the reactor is insufficient, Fe2O3 reacts with H2S to generate FeS. FeS is an activator of the Claus reverse reaction, which promotes the reaction of sulfur with water to generate H2S and SO2, resulting in excessively high concentrations of SO2 and H2S in the tail gas and increased SO2 emissions in the flue gas. The regeneration method of the present invention can solve the above-mentioned problems, realize efficient regeneration of the catalyst, and efficient preparation of sulfur. The relevant reactions of catalyst regeneration are:

[0047] FeS is the active agent of the Claus reverse reaction: 3S+2H2O→2H2S+SO2 (1)

[0048] The regeneration process of the present invention uses Claus tail gas and oxygen raw materials to regenerate the selective oxidation catalyst, FeS reacts with O2 to generate Fe2(SO4)3 and Fe2O3, and in the presence of H2S, H2S reacts with Fe2(SO4)3 to generate FeSO4, and FeSO4 continues to react with H2S to generate FeS, which is oxidized by oxygen to Fe2O3.

[0049] 3FeS + 6.75O2 →Fe2(SO4)3+0.5Fe2O3 (2)

[0050] Fe2(SO4)3+H2S→2FeSO4+H2SO4+S (3)

[0051] 2FeSO4+8H2S→8FeS+8S+8H2O (4)

[0052] After reaction (4), reaction (2) continues to occur, and the cycle repeats until FeS is converted into Fe2O3 and activation is completed.

[0053] According to a preferred embodiment of the present invention, the first Claus tail gas and the second Claus tail gas are independently obtained by subjecting a hydrogen sulfide feedstock and an oxygen feedstock to at least one, preferably 3-4, Claus reactions.

[0054] The Routh tail gas refers to the gas phase discharge from the last stage sulfur condenser in the upstream process of the selective oxidation reactor.

[0055] like Figure 1 As shown, the present invention provides a sulfur preparation device, which includes: a reaction furnace 1, a waste heat boiler 2, a primary sulfur condenser 3, a primary heater 4, a primary reactor 5, a secondary sulfur condenser 6, a secondary heater 7, a secondary reactor 8, a tertiary sulfur condenser 9, a tertiary heater 10, a tertiary reactor 11, a quaternary sulfur condenser 12, a quaternary heater 13, a selective oxidation reactor 14, a quintuple sulfur condenser 15, an incinerator 16, an alkali washing tower 17, and a chimney 18, which are connected in series in sequence; liquid sulfur outlets are arranged on each sulfur condenser and connected to a liquid sulfur pool; a regeneration air pipeline is connected to the connecting pipeline between the quaternary sulfur condenser 12 and the quaternary heater 13.

[0056] The preparation process includes: in the selective oxidation reactor 14, hydrogen sulfide is converted into sulfur under the catalytic action of a fresh catalyst until the catalyst is deactivated,

[0057] (1) gradually reducing the inlet temperature of the selective oxidation reactor 14 to 170-200° C., preferably 180-190° C.;

[0058] (2) Adjust (reduce) the air supply to the reactor so that the H2S concentration at the inlet of the selective oxidation reactor (Claus tail gas) is between 0.3% and 1%, and the SO2 concentration is ≯0.04%. This gas (first Claus tail gas) serves as the regeneration acid gas for the selective oxidation catalyst;

[0059] (3) introducing a first oxygen-containing feedstock such as air before the fourth-stage heater so that the volume ratio of the first Claus tail gas to the first oxygen-containing feedstock is 10:1-5:1 (under this ratio range, the volume concentration of oxygen in the gas phase at the reactor outlet during regeneration is not less than 5%), and regeneration is performed to make the selective oxidation reactor operate in an oxygen-rich state;

[0060] (4) gradually increasing the reaction temperature at 10-20°C / h to regenerate the catalyst until the inlet temperature reaches 180-250°C, preferably 200-240°C, and the regeneration temperature is 180-260°C, preferably 200-250°C, and the regeneration is performed for 10-72 hours, preferably 24-60 hours;

[0061] (5) After regeneration is completed, gradually reduce the reactor inlet temperature to 180-230°C, preferably 200-220°C;

[0062] (6) Adjust the air supply of the incinerator so that the H2S concentration at the inlet of the selective oxidation reactor is between 0.3% and 1%;

[0063] (7) adjusting the regeneration air volume (the volume ratio of the second Claus tail gas to the second oxygen-containing feedstock is 20:1-5:1, preferably 15:1-7:1) so that the O2 content at the outlet of the selective oxidation reactor is about 0.5%-2% (V), and operating under overoxygen conditions is maintained;

[0064] (8) Put into normal production.

[0065] The following will be done by adopting Figure 1 The present invention is described in detail by way of the embodiments of the scheme. In the following embodiments, the H2S conversion rate and the selectivity parameters of the generated sulfur are measured by a sulfur microreactor evaluation device; the raw materials are all commercially available products.

[0066] Example 1

[0067] A 15,000 ton / year sulfur recovery unit uses a selective oxidation process to recover sulfur. Two years after it was put into operation, the selective oxidation reactor was calibrated and it was found that the H2S conversion rate and the selectivity of sulfur generation in the selective oxidation reactor were greatly reduced. It was judged that the catalyst was seriously deactivated. After checking the historical records, no temperature runaway phenomenon was found in the bed. It was initially judged that the catalyst was in an oxygen-deficient state, so the catalyst needed to be regenerated. The regeneration steps are as follows:

[0068] (1) gradually reducing the inlet temperature of the selective oxidation reactor by 190°C;

[0069] (2) Reduce the air supply to the reactor so that the H2S concentration at the inlet of the selective oxidation reactor (Claus tail gas) is around 0.7% and the SO2 concentration is ≤ 0.04%. This gas is used as the regeneration acid gas for the selective oxidation catalyst;

[0070] (3) Air is introduced before the fourth-stage heater for regeneration, and the volume ratio of Claus tail gas and oxygen is controlled to be 6:1 (under this ratio range, the volume concentration of oxygen in the gas phase at the reactor outlet during regeneration is not less than 5%), so that the selective oxidation reactor operates in an oxygen-rich state;

[0071] (4) The catalyst was regenerated by gradually increasing the reaction temperature at 10°C / h until the inlet temperature reached 240°C. The regeneration temperature was 260°C and the regeneration time was 48 hours.

[0072] (5) After regeneration is completed, the reactor inlet temperature is gradually reduced to 230°C;

[0073] (6) Adjust the air supply of the incinerator so that the H2S concentration at the inlet of the selective oxidation reactor is around 0.5%;

[0074] (7) adjusting the regeneration air volume so that the O2 content at the outlet of the selective oxidation reactor is about 1.5% (V) (at this time, the volume ratio of Claus tail gas to regeneration air volume is in the range of 20:1-5:1), and maintaining operation under peroxygen conditions;

[0075] (8) Put into normal production.

[0076] After activation, normal operating conditions are restored, the H2S conversion rate is above 95%, the selectivity of generated sulfur is >90%, which is equivalent to the activity of fresh catalyst, and the regeneration effect is good.

[0077] Example 2

[0078] A 5,000 ton / year sulfur recovery unit uses a selective oxidation process to recover sulfur. One year after it was put into operation, the selective oxidation reactor was calibrated and it was found that the H2S conversion rate and the selectivity of sulfur generation in the selective oxidation reactor were greatly reduced. It was judged that the catalyst was seriously deactivated. After checking the historical records, no temperature runaway phenomenon was found in the bed. It was initially judged that the catalyst was in an oxygen-deficient state, so the catalyst needed to be regenerated. The regeneration steps are as follows:

[0079] (1) gradually reducing the inlet temperature of the selective oxidation reactor by 180°C;

[0080] (2) Reduce the air supply to the reactor so that the H2S concentration at the inlet of the selective oxidation reactor (Claus tail gas) is around 0.8% and the SO2 concentration is ≤ 0.04%. This gas is used as the regeneration acid gas for the selective oxidation catalyst;

[0081] (3) Air is introduced before the four-stage heater for regeneration, and the volume ratio of Claus tail gas and oxygen is controlled to be 7:1 (under this ratio range, the volume concentration of oxygen in the gas phase at the reactor outlet during regeneration is not less than 5%), so that the selective oxidation reactor operates in an oxygen-rich state;

[0082] (4) The catalyst was regenerated by gradually increasing the reaction temperature at 20°C / h until the inlet temperature reached 220°C. The regeneration temperature was 240°C and the regeneration time was 24 hours.

[0083] (5) After regeneration is completed, the reactor inlet temperature is gradually reduced to 205°C;

[0084] (6) Adjust the air supply of the incinerator so that the H2S concentration at the inlet of the selective oxidation reactor is around 0.4%;

[0085] (7) adjusting the regeneration air volume so that the O2 content at the outlet of the selective oxidation reactor is about 1.0% (V) (at this time, the volume ratio of Claus tail gas to regeneration air is in the range of 20:1-5:1), and maintaining operation under peroxygen conditions;

[0086] (8) Put into normal production.

[0087] After activation, normal operating conditions are restored, the H2S conversion rate is above 95%, the selectivity of generated sulfur is >90%, which is equivalent to the activity of fresh catalyst, and the regeneration effect is good.

[0088] Example 3

[0089] A 10,000 ton / year sulfur recovery unit uses a selective oxidation process to recover sulfur. Three years after it was put into operation, the selective oxidation reactor was calibrated and it was found that the H2S conversion rate and the selectivity of sulfur generation in the selective oxidation reactor were greatly reduced. It was judged that the catalyst was seriously deactivated. After checking the historical records, no temperature runaway phenomenon was found in the bed. It was initially judged that the catalyst was in an oxygen-deficient state, so the catalyst needed to be regenerated. The regeneration steps are as follows:

[0090] (1) gradually reducing the selective oxidation reactor inlet temperature by 185°C;

[0091] (2) Reduce the air supply to the reactor so that the H2S concentration at the inlet of the selective oxidation reactor (Claus tail gas) is around 0.3% and the SO2 concentration is ≤ 0.04%. This gas is used as the regeneration acid gas for the selective oxidation catalyst;

[0092] (3) Air is introduced before the four-stage heater for regeneration, and the volume ratio of Claus tail gas and oxygen is controlled to be 8:1 (under this ratio range, the volume concentration of oxygen in the gas phase at the reactor outlet during regeneration is not less than 5%), so that the selective oxidation reactor operates in an oxygen-rich state;

[0093] (4) The catalyst was regenerated by gradually increasing the reaction temperature at 15°C / h until the inlet temperature reached 210°C. The regeneration temperature was 220°C and the regeneration time was 32 hours.

[0094] (5) After regeneration is completed, gradually reduce the reactor inlet temperature to 200°C;

[0095] (6) Adjust the air supply of the incinerator so that the H2S concentration at the inlet of the selective oxidation reactor is around 0.5%;

[0096] (7) adjusting the regeneration air volume so that the O2 content at the outlet of the selective oxidation reactor is about 0.8% (V) (the volume ratio of the second Claus tail gas to the second oxygen-containing feedstock is 20:1-5:1, preferably 15:1-7:1), and operating under peroxygen conditions;

[0097] (8) Put into normal production.

[0098] During the regeneration process, the catalyst bed reaction temperature is strictly controlled below 280°C. When the temperature is over-temperature, the temperature is lowered by reducing the inlet H2S concentration or reducing the reactor inlet temperature, etc., which does not affect the catalyst activity. After the activation is completed, the normal operating conditions are restored, the H2S conversion rate is above 95%, and the selectivity of sulfur generation is >90%, which is equivalent to the activity of fresh catalysts, indicating that the regeneration effect is good.

[0099] Example 4

[0100] The same as Example 1, except that in step (3), the amount of air introduced before the fourth-stage heater is adjusted so that the volume ratio of the regenerated acid gas to the first oxygen-containing raw material is 10:1.

[0101] The H2S conversion rate is above 90%, and the selectivity of sulfur generation is >85%.

[0102] Example 5

[0103] Same as Example 1, except that (2) the air distribution of the reactor is adjusted so that the H2S concentration at the inlet of the selective oxidation reactor (Claus tail gas) is 1.2%.

[0104] The H2S conversion rate is above 85%, and the selectivity of sulfur generation is >83%.

[0105] Example 6

[0106] Same as Example 1, except that the regeneration temperature inlet is maintained at 190°C.

[0107] The H2S conversion rate is above 90%, and the selectivity of sulfur generation is >80%.

[0108] Comparative Example 1

[0109] A 20,000 ton / year sulfur recovery unit adopted a selective oxidation process to recover sulfur. The SO2 emission concentration of the flue gas from the sulfur recovery unit continued to be high. The H2S concentration at the inlet and outlet of the selective oxidation reactor was sampled and analyzed. It was calculated that the H2S conversion rate of the catalyst in the selective oxidation reactor was between 20% and 40%, and the selectivity of sulfur generation was between 20% and 45%. The catalyst was severely deactivated, so the unit was shut down for catalyst replacement. The catalyst was used for only two and a half years, resulting in high operating costs for the unit.

[0110] Comparative Example 2

[0111] The same as Example 1, except that step (2) is not performed, that is, the regenerated acid gas is not passed.

[0112] After regeneration, the H2S conversion rate is above 78%, and the selectivity of generated sulfur is >70%.

[0113] Comparative Example 3

[0114] The same as Example 1, except that in step (3), the amount of air introduced before the fourth-stage heater is adjusted so that the oxygen content in the contact regeneration gas phase product flow is 2%.

[0115] After regeneration, the H2S conversion rate is above 80%, and the selectivity of generated sulfur is >83%.

[0116] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing sulfur, characterized in that: The preparation method comprises at least one alternating regeneration step and production step after the catalyst is deactivated; The regeneration step comprises introducing the first Claus tail gas and the first oxygen-containing feedstock into a selective oxidation reactor to regenerate the catalyst, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not less than 5% during regeneration; The production step comprises introducing the second Claus tail gas and the second oxygen-containing raw material into a selective oxidation reactor for catalytic reaction, wherein the oxygen volume concentration in the gas phase at the reactor outlet is not greater than 2% during the reaction.

2. The preparation method according to claim 1, wherein The H2S concentration in the first Claus tail gas is 0.3-1%, and the SO2 concentration is ≯0.04%; and / or The H2S concentration in the second Claus tail gas is 0.3-1%; and / or During the reaction, the oxygen volume concentration in the gas phase at the reactor outlet is 0.5-2%.

3. The preparation method according to claim 1 or 2, wherein: The inlet temperature of the selective oxidation reactor during the catalyst regeneration is higher than the inlet temperature of the selective oxidation reactor during the catalytic reaction, preferably 5-40°C higher, further preferably 5-20°C higher, and more preferably 10-15°C higher.

4. The preparation method according to any one of claims 1 to 3, wherein The preparation method carries out 1-2 alternating regeneration steps and production steps after the catalyst is deactivated.

5. The preparation method according to any one of claims 1 to 4, wherein: The oxygen volume concentration in the first oxygen-containing raw material is above 10%; and / or The volume concentration of oxygen in the second oxygen-containing raw material is 5-21%.

6. The preparation method according to any one of claims 1 to 5, wherein: The conditions for the catalyst regeneration include: The volume ratio of the first Claus tail gas to the first oxygen-containing feedstock is 10:1-5:1, preferably 6:1-8:1; and / or The inlet temperature of the selective oxidation reactor is 180-250°C, preferably 200-240°C; and / or The regeneration temperature is 180-260°C, preferably 200-250°C; and / or The regeneration time is 10-72h, preferably 24-60h.

7. The preparation method according to any one of claims 1 to 6, wherein: The conditions of the catalytic reaction include: The volume ratio of the second Claus tail gas to the second oxygen-containing feedstock is 20:1-5:1, preferably 15:1-7:1; and / or Selecting the oxidation reactor inlet temperature to be 180-230°C, preferably 200-220°C; and / or The reaction temperature is 170-240°C, preferably 200-240°C; and / or The reaction time is 8-72h, preferably 24-60h.

8. The preparation method according to any one of claims 1 to 7, wherein: After the catalytic reaction is completed, the inlet temperature of the selective oxidation reactor is reduced to 170-200° C., preferably 180-190° C.; During regeneration, the reactor inlet temperature is increased to the regeneration temperature at a rate of 10-20°C / h; After regeneration is completed, the inlet temperature of the selective oxidation reactor is lowered to the reaction temperature.

9. The preparation method according to any one of claims 1 to 8, wherein: The active component of the catalyst in the selective oxidation reactor comprises iron oxide.

10. The preparation method according to any one of claims 1 to 9, wherein: The first Claus tail gas and the second Claus tail gas are independently obtained by reacting a hydrogen sulfide feedstock and an oxygen feedstock at least once, preferably 3-4 times.

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