Integrated hydrogen and sulfuric acid production methods from hydrogen sulfide

Abstract

An integrated chemical process for the production of sulfuric acid is described, that combines a process of producing sulfuric acid from SO2, and a process of producing hydrogen and SO2 from the reaction of hydrogen sulfide, iodine and water. Sulfur dioxide produced from this process is first separated from the liquid effluent using a flash separation process. The resulting sulfur dioxide stream can be purified using an absorber or adsorber unit. The sulfur dioxide is then diluted with air to the desired stoichiometric conditions and fed into a sulfuric acid reactor. This reactor can consist of a contact process, wet sulfuric acid process, or sulfur electrolysis process. The effluent of this reactor is concentrated sulfuric acid, which is a valuable commodity chemical.

Description

Docket No.: 6196.1004-001Integrated hydrogen and sulfuric acid production methods from hydrogen sulfideRELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 700,053, filed on September 27, 2024. The entire teachings of the above application are incorporated herein by reference.BACKGROUND

[0002] Sulfuric acid is a mineral acid and one of the most important commodity chemicals in the world. It is highly corrosive and a good oxidizing agent, which makes it useful in a variety of industrial applications, including fertilizer production, pulp and paper production, oil refining, and wastewater treatment. It can also be used as a catalyst in a variety of chemical reactions.

[0003] Sulfuric acid can be produced via several pathways, including the contact process and wet sulfuric acid process (WSA), the two most common production pathways used today. Each process starts with sulfur dioxide, which is usually generated by burning sulfur, but can also come from metallurgical processes or burning spent sulfuric acid. In the contact process (US2079760A), the sulfur dioxide is oxidized to sulfur trioxide under a vanadium (V) oxide catalyst at high temperature (450 °C). The sulfur trioxide is then absorbed into concentrated sulfuric acid to form oleum (fuming sulfuric acid). The oleum is diluted with water to form concentrated sulfuric acid.

[0004] The wet sulfuric acid process follows a similar approach (US7361326B2). However, instead of the sulfur trioxide being absorbed in concentrated sulfuric acid, it is hydrated by water to generate sulfuric acid directly. In the final step, the gaseous sulfuric acid is condensed into a liquid.

[0005] Other methods for sulfuric acid generation are also used but are far less common or not at an industrial scale. These include the lead chamber process, metabisulfite process, and sulfur electrolysis (US11965258B1).

[0006] The process described in US20200369518 presents a new method for the generation of sulfur dioxide. This process co-generates hydrogen gas and sulfur dioxide from the decomposition of hydrogen sulfide. This process has the following net overall reaction: H2S + 2H2O 3H2+ SO214219176.vlDocket No.: 6196.1004-001

[0007] For every mole of H2S, one mole of SO2 is generated. Since the reaction directly forms SO2, it can be more readily converted to sulfuric acid. Historically, hydrogen sulfide was first converted to sulfur via the Claus process, which goes through a sulfur dioxide intermediate. The elemental sulfur is then burned to produce sulfuric acid via the methods described above. This traditional method involves the following three reactions:2 H2S + 3 O2 2 SO2 + 2 H2O (Claus first step)4 H2S + 2 SO2 -^- 3 S2 + 4 H2O (Claus second step)S2 + 2 O2 — > 2 SO2 (Sulfur oxidation for sulfuric acid).

[0008] Hydrogen sulfide is created in large quantities as a byproduct of fuel desulfurization in refineries and is co-produced with natural gas. It also occurs in coal gasification, biomass gasification, wastewater treatment, and in other naturally occurring reserves. In these industries, H2S needs to be converted to less toxic components, historically through the Claus process, which has the overall reaction H2S + Yi O2 —> S + H2O. These industries happen to also have high sulfuric acid demand.

[0009] There is a need in the industry for the direct generation of sulfur dioxide that eliminates the unnecessary back and forth conversion of sulfur.SUMMARY

[0010] The present disclosure describes an integrated chemical process for the production of sulfuric acid, combining a process of producing sulfuric acid from SO2, and a process of producing hydrogen and SO2 from hydrogen sulfide, iodine and water (from hydrogen sulfide in gas phase or dissolved in liquid hydrocarbon streams, with iodine and water). The present disclosure also pertains to methods and equipment for the removal of sulfur dioxide from a liquid stream containing water, iodine and hydriodic acid and the use of an iodine chemical cycle to produce hydrogen gas from the byproducts of this purification.

[0011] In one version, the disclosure pertains to methods for producing sulfuric acid from sulfur dioxide, comprising: reacting a hydrogen sulfide dissolved, mixed or entrained in a hydrocarbon with water and iodine under conditions to form a purified hydrocarbon stream and a liquid stream comprising sulfur dioxide and hydriodic acid; separating the sulfur dioxide from the liquid stream and the hydriodic acid; and converting sulfur dioxide to sulfuric acid. In embodiments of this version, reaction products such as HI can be further processed to decompose / recycle HI and produce / collect hydrogen gas. In other embodiments24219176. vlDocket No.: 6196.1004-001 of this version, the sulfur dioxide product stream can be further processed into sulfuric acid by a contact process, a wet sulfuric acid process, or by an electrolyzer process.

[0012] The methods of the disclosure can be performed in a first reactor to react hydrogen sulfide with iodine and water to form a mixture of dissolved hydriodic acid and sulfur dioxide; a first vapor-liquid separator to separate the sulfur dioxide from the mixture of dissolved hydriodic acid and sulfur dioxide; a second reactor to dissociate the hydroiodic acid into a reactor effluent stream comprising hydrogen and iodine; a second vapor-liquid separator to separate the hydrogen from the reactor effluent stream; and a third reactor to react the sulfur dioxide to form sulfuric acid. In one embodiment, the method further comprises an absorption or adsorption unit to purify the sulfur dioxide. In another embodiment, the method further comprises an air dilution unit to dilute the sulfur dioxide to necessary reaction conditions. In yet another embodiment, the method further comprises a waste heat boiler to convert excess heat from the sulfuric acid reactor into steam.

[0013] The ability to generate both hydrogen and sulfuric acid onsite from hydrogen sulfide waste can be an advantageous and economical way to obtain necessary chemical feedstocks.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a better understanding of the present disclosure, reference is made to the drawing below, in which like elements are referenced with like numerals, and in which:

[0015] FIG. 1 is an example flowchart of a system directed to an embodiment using the contact process.

[0016] FIG. 2 is an example flowchart of a system directed to an embodiment using the wet sulfuric acid process.

[0017] FIG. 3 is an example flowchart of a system directed to an embodiment using a sulfur electrolyzer.DETAILED DESCRIPTION

[0018] The present disclosure describes an integrated chemical process for the production of sulfuric acid, combining a process of producing sulfuric acid from SO2, and a process of producing hydrogen and SO2 from hydrogen sulfide (hydrogen sulfide dissolved, mixed or entrained in a hydrocarbon), iodine and water.34219176. vlDocket No.: 6196.1004-001

[0019] Sources of hydrocarbons having hydrogen sulfide dissolved, mixed or entrained in a hydrocarbon that can be purified in the disclosed process can be a gas or liquid hydrocarbon stream. Examples of gas hydrocarbon streams include, but are not limited to, raw sour gas from natural gas industry; gasified gas from coal gasification industry; high concentration H2S gas from desulfurization process in refineries. Examples of liquid hydrocarbon streams include, but are not limited to, naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil, and heavy petroleum or oil residue within a petroleum refinery.

[0020] The reaction of H2S with I2 is thermodynamically favorable, exothermic, with mass-transfer limited kinetics. See, Ryan J. Gillis, Phalgun Lolur, and William H. Green, ACS Sustainable Chemistry & Engineering 2019 7 (7), 7369-7377. The reaction proceeds according to the following stoichiometry:H2S + 312 + 2 H2O 6HI + SO2

[0021] The resulting SO2 may be dissolved in the liquid stream. The resulting SCh may further react in situ to a different form, including but not limited to elemental sulfur, sulfate, or other oxidized sulfur form. This reaction occurs in a first reactor, as detailed in US20200369518, the entire teachings of which are incorporated herein by reference. The Hl / water mixture is then sent to a second reactor, where the HI is catalytically decomposed into hydrogen and iodine.

[0022] The sulfuric acid reaction comprises or consists of first passing a feed of about 0.1 vol% to about 40 vol% sulfur dioxide over one or more catalyst beds to form sulfur trioxide. This reaction occurs following the stoichiometry:2 SO2 + O2 2 SO3

[0023] In one embodiment, the resulting sulfur trioxide is absorbed into about 97% to about 98% sulfuric acid (H2SO4) to form oleum (H2S2O7). The oleum is then diluted with water to form concentrated sulfuric acid. Both of these reactions are well understood.H2SO4 + SO3 H2S2O7H2S2O7 + H2O 2 H2SO4

[0024] Not all of the SO3 may be absorbed by sulfuric acid, so a second absorption stage can be utilized to improve overall absorption.

[0025] In another embodiment, the resulting sulfur trioxide is absorbed into water, forming sulfuric acid H2SO4. The resulting gaseous sulfuric acid is condensed to about 97% to about 98% liquid sulfuric acid.SO3 + H2O H2SO4 (g)44219176. vlDocket No.: 6196.1004-001H2SO4 (g) H2SO4 (1)

[0026] This reaction is highly exothermic. In one embodiment, the heat is captured by a waste heat boiler, which produces high pressure steam that can be used as an additional heat supply. Additionally, not all the SCh may react, or the SO3 be absorbed, so additional catalytic reactors can be employed to improve conversion.

[0027] Sulfuric acid produced according to the methods of the disclosure have wide applications in industry, including but are not limited to, chemical manufacturing, metal processing, fertilizer manufacturing, refining, and wastewater treatment. For implementations of this chemical process in refineries, the sulfuric acid may be used in the production of alkylate. In a wastewater treatment application, the sulfuric acid may be used for pH adjustment. For an implementation of this chemical process in gas processing, the sulfuric acid may be used by nearby chemical and fertilizer manufacturing.

[0028] The process for producing sulfur dioxide from an iodine chemical cycle (US20200369518) can result in a sulfur dioxide stream with a purity of 30 vol%, up to high purity 99 vol% sulfur dioxide. The high purity sulfur dioxide stream may need to be diluted with air to achieve the desired stoichiometric ratio for the sulfuric acid reaction embodiments, where the sulfur dioxide is about 0.1 vol% to about 40 vol%. The production of sulfur dioxide occurs in a reactor where H2S is reacted with I2 and H2O to form a mixture of dissolved HI and SO2. The SO2 is separated from the liquid stream, possibly using a flash vessel, where it can then be further purified and diluted for use in sulfuric acid manufacturing processes. It may be that not all the sulfur dioxide is removed in the first separation after the H2S reaction unit (1), as illustrated in FIGs. 1, 2 and 3. It may be that some or all of the sulfur dioxide reacts to another sulfur form, including but not limited to elemental sulfur, sulfate, or other oxidized sulfur form. It may be that sulfur dioxide stays dissolved in the HI liquid, which is then released when HI is decomposed into hydrogen. The resulting gas stream consisting of hydrogen and small amounts of sulfur dioxide would then need to be purified.

[0029] In one embodiment, the SO2 is separated from the liquid stream after the first reactor by flashing between about 0.1 percent to about 30 percent of the liquid stream to vapor at a temperature between about 80 °C to about 250 °C and a pressure between about 1 bar to about 50 bar. This may be performed by a vapor-liquid separator, such as a flash drum, which is shown as the “SO2 removal” unit (2) in FIGs. 1, 2, and 3.

[0030] In another embodiment, the SO2 is separated from the liquid stream after the first reactor using a stripper to remove the dissolved gas from the liquid stream. This may be54219176. vlDocket No.: 6196.1004-001 performed in a separator including a plate column, packed column, spray tower, bubble column, or centrifugal contactor, which is shown as the “SO2 removal” unit (2) in FIGs. 1, 2, and 3. The liquid stream with entrained SO2 is fed into the top of the unit, while the stripping agent is fed into the bottom. Typical stripping agents include steam, air, inert gases, and hydrocarbons. The stripper may be heated between about 40 °C to about 250 °C to improve separation.

[0031] Sulfur forms other than sulfur dioxide may be separated via filtration, membranes, or decanting and isolated or converted back to sulfur dioxide, which is then joined with the rest of the sulfur dioxide for further processing. Conversion methods include oxidation, reduction, combustion, and Bunsen reaction. This equipment would be part of the “SO2 removal” unit (2) in FIGs. 1, 2, and 3.

[0032] In another embodiment, some or all the SO2 is retained in the liquid stream, which needs to be separated after the HI decomposition reactor. Here, the gas stream of hydrogen and sulfur dioxide is separated. This may be performed using an absorption or adsorption unit that could use water or another polar solvent, which is illustrated as the “optional hydrogen purification” unit (4) in FIGs. 1, 2, and 3.

[0033] In another embodiment, the absorption or adsorption unit is used to further purify the sulfur dioxide stream. The absorbing stream could include the primary inlet or primary recycle stream. The absorption unit may be any suitable device, including but not limited to a bubble column, a Venturi scrubber, a falling film absorber, a tray or a packed column, which is illustrated as the “optional SO2 purification” unit (5) in FIGs. 1, 2, and 3.

[0034] The process is comprised of the majority of the thermochemical cycle described in US20200369518, with a novel additional reactor (or reactors) for converting sulfur dioxide into sulfuric acid. This conversion can be accomplished across a single or multiple reactors in parallel or in series. These reactors can take the form of a simple column reactor (packed or unpacked, staged or unstaged).

[0035] Once the SO2 stream is purified, it can be diluted with an air stream for the optimal stoichiometric ratio of sulfur dioxide and oxygen. In one embodiment, a stream of sulfur dioxide of about 0.1 vol% to about 40 vol% at about 1 bar to about 3 bar is heated to about 300 °C to about 500 °C and passed over one or more catalyst beds to form sulfur trioxide. The resulting sulfur trioxide is absorbed into about 97% to about 98% sulfuric acid H2SO4 to form oleum H2S2O7. The oleum is then diluted with water to form concentrated64219176. vlDocket No.: 6196.1004-001 sulfuric acid. Not all of the SO3 may be absorbed by sulfuric acid, so a second absorption stage can be utilized to improve overall absorption.

[0036] In another embodiment, a stream of sulfur dioxide of about 0.1 vol% to about 40 vol% at about 1 bar to about 3 bar is heated to about 300 °C to about 500 °C. The sulfur dioxide stream is passed over one or more catalyst beds (illustrated as catalytic oxidation unit (7) in the figures) to form sulfur trioxide. The resulting sulfur trioxide is absorbed into water, forming sulfuric acid (H2SO4). This reaction is highly exothermic. In this embodiment, the heat may be captured by a waste heat boiler (not shown in FIG. 2) which is operatively connected to the catalytic oxidation reactor (7) and / or the sulfur trioxide hydration unit (11), which produces high pressure steam that can be used as additional heat supply. The resulting gaseous sulfuric acid is condensed to about 97% to about 98% liquid sulfuric acid.Additionally, not all the SO2 may react, or the SO3 be absorbed, so additional catalytic reactors can be employed to improve conversion.

[0037] In another embodiment, a stream of sulfur dioxide of about 10 vol% to about 90 vol% is sent to a sulfur electrolyzer with water, which is shown in FIG. 3 (unit (13)). The electrolyzer is preferably operated at elevated temperatures between about 50 °C to about400°C and with a differential pressure greater than about 20 bar to about 100 bar. The resulting products are sulfuric acid (H2SO4) and hydrogen gas (H2). Additional separation of impurities in the H2SO4 and H2 streams may be desirable. Any unreacted SO2 can be recycled back to the electrolyzer.

[0038] Due to the equilibrium and reaction kinetics of the H2SO4 reactions, there may be some SO2 left after passing through the reactor. This SO2 can be recycled for further conversion in FIG. 2, or it can be sent to a tail gas treater (10) in FIG. 1.

[0039] Turning to an example process illustrated in FIG. 1 using the contact process, H2S and hydrocarbons are directed into an H2S reactor (1) comprising iodine and water, where H2S is reacted with I2 and H2O to form a mixture of dissolved HI and SO2. Purified hydrocarbons (gas or liquid) exit the reactor as a hydrocarbon stream and the generated SO2 exits the reactor in a liquid stream with I2, H2O, HI, and SO2 to an SO2 removal unit (2), for further processing into sulfuric acid. In embodiments, the SO2 removal unit (2) can be a vapor-liquid separator, such as a flash drum. The dissolved hydriodic acid (HI) is processed in an HI decomposition unit (3) to produce HI / I2 / H2O which is recycled back to the H2S reactor (1). Hydrogen gas generated in the HI decomposition unit (3) can be optionally purified in a hydrogen purification unit (4) and collected as a purified hydrogen stream and74219176. vlDocket No.: 6196.1004-001 residual SO2 from this purification is directed to the SO2 product stream. The SO2 stream can be diluted with air or optionally be purified in a SO2 purification unit (5) and then diluted with air in the air dilution unit (6) to a range of 0.1 vol% to 40 vol% sulfur dioxide. The resulting sulfur dioxide is oxidized to sulfur trioxide under a vanadium (V) oxide catalyst at high temperature (about 450 °C). Alumina (AI2O3) may also be used as a catalyst. The sulfur trioxide is then absorbed into concentrated sulfuric acid to form oleum (fuming sulfuric acid). The oleum is diluted with water to form concentrated sulfuric acid. The process can optionally comprise recycling unreacted SO2 back to the SO2 process stream and / or treating unreacted SO2 in a tail gas treater unit (10). The tail gas treaters (TGT) are used to remove minor impurities (<5 mol%) that remain in the stream after sulfur treating, to release the gas stream while meeting environmental regulations on sulfur species. Multiple established technologies are used for this process, including amine-based TGTs, caustic scrubbers, Shell Claus Off-gas Treatment (SCOT), Ruichang TGT, Lummus Resulf, Eastman AdapT, among others.

[0040] FIG. 2 is an example process using the wet sulfuric acid process. Features in common with FIG. 1 are as discussed above. After production of SO3, the SO3 stream proceeds to an SO3 Hydrator unit (11) where the SO3 is hydrated by water to generate sulfuric acid directly. In the final step, the gaseous sulfuric acid is condensed into a liquid. The process can optionally comprise recycling unreacted SO2 back to the SO2 process stream and / or treating unreacted SO2 in a tail gas treater unit (10).

[0041] FIG. 3 is an example process using an electrolyzer after air dilution of SO2. Features in common with FIG. 1 are as discussed above. Diluted SO2 is processed in an SO2 electrolyzer unit (13) in the presence of water to form sulfuric acid. Any hydrogen gas and unreacted SO2 can be processed back to the optional hydrogen purification unit (4) for recycling. The sulfuric acid can be optionally purified in an optional sulfuric purification unit (14). The present method has many advantages over previous methods of generating sulfur dioxide for sulfuric acid production. Previously, sulfur dioxide came from burning sulfur. While this highly exothermic reaction can be utilized in a waste heat boiler, solid sulfur is most commonly generated from the treatment and handling of hydrogen sulfide. Therefore, the sulfur cycle is removing H2S from oil and gas streams, converting the H2S to sulfur via the Claus process, shipping the sulfur as the feedstock of sulfur dioxide, combusting the sulfur to create sulfur dioxide, and then using the sulfur dioxide to make sulfuric acid. The processes described herein simplify the process by converting H2S directly into sulfur84219176. vlDocket No.: 6196.1004-001 dioxide, which can then be utilized onsite for sulfuric acid production. This offers another revenue stream for plants with hydrogen sulfide, and reduces dependence on the Claus system, which is a low-value process. Currently, refinery makes elemental sulfur, and chemical plants take sulfur to make sulfuric acid. By implementing the method in this application, the sulfur production and the sulfuric acid production are integrated, which avoids the cost of sulfur shipping and transportation. Moreover, sulfuric acid could be used within the refinery campus, such as Alkylation unit or other refining processes.Definitions

[0042] It is to be understood that the terminology used herein is for describing particular embodiments only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.

[0043] Although any methods and materials similar or equivalent to those described herein may be used in the practice for testing of the present disclosure, exemplary materials and methods are described herein.

[0044] When a list is presented, unless stated otherwise, it is to be understood that each individual element of that list, and every combination of that list, is a separate embodiment. For example, a list of embodiments presented as “A, B, or C” is to be interpreted as including the embodiments, “A,” “B,” “C,” “A or B,” “A or C,” “B or C,” or “A, B, or C ”

[0045] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. The conjunctive term “and / or” between multiple recited elements is understood as encompassing both individual and combined options. For instance, where two elements are conjoined by “and / or,” a first option refers to the applicability of the first element without the second. A second option refers to the applicability of the second element without the first. A third option refers to the applicability of the first and second elements together. Any one of these options is understood to fall within the meaning, and therefore satisfy the requirement of the term “and / or” as used herein. Concurrent applicability of more than one of the options is also understood to fall within the meaning, and therefore satisfy the requirement of the term “and / or.”

[0046] Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and synonyms and variants thereof such as “have” and94219176. vlDocket No.: 6196.1004-001“include”, as well as variations thereof, such as “comprises” and “comprising”, are to be construed in an open, inclusive sense, e.g., “including, but not limited to.” The transitional terms “comprising,” “consisting essentially of,” and “consisting of’ are intended to connote their generally accepted meanings in the patent vernacular; that is, (i) “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open- ended and does not exclude additional, unrecited elements or method steps; (ii) “consisting of’ excludes any element or step not specified in the claim; and (iii) “consisting essentially of’ limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention. Embodiments described in terms of the phrase “comprising” (or its equivalents) also provide as embodiments those independently described in terms of “consisting of’ and “consisting essentially of.”

[0047] “About” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, z.e., the limitations of the measurement system. Unless explicitly stated otherwise within the disclosure, claims, result or embodiment, “about” means within one standard deviation per the practice in the art, or can mean a range of ± 20%, ± 10%, ± 5%, ±4, ±3, ±2 or ± 1% of a given value. It is to be understood that the term “about” can precede any particular value specified herein, except for particular values used in the Examples. For example, an “about” azeotropic mixture of hydriodic acid and water will include 57 wgt% by weight (±10 %).

[0048] All percents are intended to be weight percent unless otherwise specified. The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein.104219176. vlDocket No.: 6196.1004-001

[0049] The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein.114219176. vl

Claims

Docket No.: 6196.1004-001What is claimed is:

1. A method of producing sulfuric acid from a sulfur dioxide stream, which composes of mainly sulfur dioxide with other sulfur compounds including elemental sulfur and other oxidized sulfur species, comprising: a) reacting a hydrogen sulfide dissolved, mixed or entrained in a hydrocarbon with water and iodine under conditions to form a purified hydrocarbon stream and a liquid stream comprising hydriodic acid and sulfur dioxide; b) separating the sulfur dioxide from the liquid stream and the hydriodic acid; and c) converting the sulfur dioxide to sulfuric acid.

2. The method of claim 1, wherein the sulfur dioxide is separated from the liquid stream by partially flashing the liquid stream.

3. The method of claim 1, wherein the sulfur dioxide is separated from the liquid stream by using a stripping separation process.

4. The method of claim 1, wherein the other sulfur compounds including elemental sulfur and other oxidized sulfur species are converted to sulfur dioxide for further processing.

5. The method of claim 1, wherein the sulfur dioxide is separated from hydrogen gas by an absorption or adsorption unit that uses water or another polar solvent.

6. The method of claim 1, further comprising catalytically decomposing the hydriodic acid into hydrogen gas and iodine.

7. The method of claim 1, wherein the sulfur dioxide is subjected to a sulfuric acid contact process to create sulfuric acid.

8. The method of claim 1, wherein the sulfur dioxide is subjected to a wet sulfuric acid process to create sulfuric acid.

9. The method of claim 1, wherein the sulfur dioxide is subjected to a sulfur electrolyzer to produce sulfuric acid and hydrogen gas.

10. The method of any one of claims 7, 8, and 9, wherein unreacted sulfur dioxide is recycled to react further to sulfuric acid.

11. The method of claim 1, further comprising an absorption or adsorption unit to purify the sulfur dioxide.124219176. vlDocket No.: 6196.1004-00112. The method of claim 1, further comprising an air dilution unit to dilute the sulfur dioxide.

13. The method of claim 1, further comprising a waste heat boiler to convert excess heat from the sulfuric acid reactor into steam.

14. The method of claim 1, wherein the method is performed in a first reactor to react hydrogen sulfide with iodine and water to form a mixture of dissolved hydriodic acid and sulfur dioxide; a first vapor-liquid separator to separate the sulfur dioxide from the mixture of dissolved hydriodic acid and sulfur dioxide; a second reactor to dissociate the hydroiodic acid into a reactor effluent stream comprising hydrogen and iodine; a second vapor-liquid separator to separate the hydrogen from the reactor effluent stream; and a third reactor to react the sulfur dioxide to form sulfuric acid.

15. The method of claim 14, further comprising an absorption or adsorption unit to purify the sulfur dioxide.

16. The method of claim 14, further comprising an air dilution unit to dilute the sulfur dioxide.

17. The method of claim 14, further comprising a waste heat boiler to convert excess heat from the sulfuric acid reactor into steam.134219176. vl

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