A liquid-liquid absorber for the treatment of sour hydrocarbon liquids using iodine

Abstract

A liquid-liquid reactor for the production of hydriodic acid and sulfur dioxide from sulfur-containing hydrocarbons or hydrogen sulfide dissolved in liquid hydrocarbon streams, iodine and water as part of a larger process for the production of hydrogen is described. Methods and equipment for the removal of sulfur from liquid hydrocarbons and the use of an iodine chemical cycle to produce hydrogen gas from the byproducts of this purification are described.

Description

A Liquid-Liquid Absorber for the Treatment of Sour Hydrocarbon Liquids using IodineRELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 678,220, filed on August 1, 2024. The entire teachings of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure is in the technical field of chemical processing and reactor design, specifically a method and equipment for the removal of sulfur from liquid hydrocarbons and the use of an iodine chemical cycle to produce hydrogen gas from the byproducts of this purification.BACKGROUND

[0003] Hydrogen iodide is a colorless vapor that readily dissolves in aqueous solutions to create a transparent solution of hydriodic acid. This acid is completely ionized in water forming iodide and hydronium ions. The mixture has an azeotrope at approximately 57 wgt% hydrogen iodide.

[0004] Hydriodic acid is a mineral acid that is used as a reducing agent and catalyst in the carbonylation of alcohols and a variety of other chemical processes (US5917089A, W02004026805A1, US9233907B1).

[0005] It has also been explored as an important intermediate in the creation of hydrogen gas from either water (US4089939A) or hydrogen sulfide (US20200369518). An important step in the production of hydrogen from hydrogen sulfide is the reactive absorption of hydrogen sulfide into a liquid solution of water, iodine, and hydriodic acid.

[0006] It has become apparent that in addition to the removal of hydrogen sulfide from gas streams, the ability to similarly remove entrained sulfur from liquid hydrocarbon streams and hydrogen sulfide dissolved in liquid hydrocarbon streams is also of value particularly in the production of marine gas oils and other liquid hydrocarbon products.SUMMARY

[0007] The present disclosure pertains to a liquid-liquid reactor for the production of hydriodic acid and sulfur dioxide from sulfur-containing hydrocarbons or hydrogen sulfide dissolved in liquid hydrocarbon streams, with iodine and water. The liquid-liquid reactor can be assembled as part of a larger process for the production of hydrogen from sulfur- containing hydrocarbons. The present disclosure also pertains to methods and equipment for the removal of sulfur from liquid hydrocarbons and the use of an iodine chemical cycle to produce hydrogen gas from the byproducts of this purification.

[0008] In one embodiment is disclosed a method of removing entrained sulfur from a liquid hydrocarbon or mixture through the oxidation of entrained sulfur atoms (in the form of a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds) to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid. These liquid hydrocarbon mixtures can include but are not limited to naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil, and heavy petroleum or oil residue. The entrained sulfur atoms can exist in all types of hydrocarbons such as but not limited to paraffins, isoparaffins, olefins, naphthenes, and aromatics. According to this method, hydrogen can be generated from hydriodic acid produced in the reaction. In an aspect of this embodiment, the sulfur is hydrogen sulfide. In another aspect, the liquid hydrocarbon or mixture is a complex hydrocarbon.

[0009] In another embodiment is disclosed a method of removing dissolved hydrogen sulfide from a liquid hydrocarbon or mixture through its oxidation to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid. According to this method, hydrogen can be generated from hydriodic acid produced in the reaction. In an aspect of this embodiment, the liquid hydrocarbon or mixture is a complex liquid hydrocarbon.

[0010] In yet another embodiment is disclosed a method of generating hydrogen from hydriodic acid produced from the reaction of a liquid hydrocarbon or mixture, such as a complex liquid hydrocarbon, with entrained sulfur atoms (in the form of a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds) with mixtures containing water, iodine, and hydriodic acid.

[0011] In an embodiment is disclosed a liquid-liquid reactive absorber comprising a liquid contacting reactor, a mixture containing water, iodine and hydriodic acid in intimate contact with a sulfur-containing hydrocarbon liquid within the liquid contacting reactor. Inembodiments, the liquid contacting reactor can be a column reactor, a mixer-settler system or a centrifugal contactor.BRIEF DESCRIPTION OF THE DRAWING

[0012] 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:

[0013] The Figure illustrates an example embodiment of a liquid-liquid reactive absorber shown at the front end of a system (delineated by the circle), as part of a larger hydrogen from hydrogen sulfide process unit.DETAILED DESCRIPTION

[0014] The present disclosure describes a liquid-liquid reactor for the production of hydriodic acid and sulfur dioxide from hydrogen sulfide, iodine and water. The purpose of the described device is for the removal of dissolved hydrogen sulfide or hydrocarbon species with entrained sulfur atoms from liquid streams, typically light hydrocarbon liquids, through reactive absorption of aqueous hydriodic acid and iodine. The reactor system may be arranged into counter-current, co-current, batch, or other arrangements.

[0015] The liquid-liquid reactor and system design, as described herein, can be incorporated as part of a larger process for the production of hydrogen. For example, the liquid-liquid reactor and system design can be incorporated at the front end of a system for the production of hydrogen, such as but not limited to a process unit as described in US20200369518, the teachings of which are incorporated herein by reference in their entirety. An exemplary system is illustrated in the FIGURE, where the liquid-liquid reactor of the disclosure is upstream and delineated by the circle. The downstream elements of the system are part of a larger process system for the production of hydrogen, as described in US20200369518, the entire teachings of the system are incorporated herein by reference.

[0016] The reactor is referred to herein as a “liquid-liquid” reactor because it is a reactive absorber for liquid streams containing hydrocarbon species with entrained sulfur atoms or dissolved hydrogen sulfide which is processed in a liquid mixture of water, iodine, and hydriodic acid.

[0017] Suitable liquid streams that can be processed according to the methods and equipment of the disclosure include but are not limited to hydrogen sulfide or sulfur containing liquids, such as sour liquid hydrocarbons, light hydrocarbon liquids, marine gas oils, natural gas liquids, hydrocarbon gas liquids, complex liquid hydrocarbon mixtures suchas but not limited to naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil and heavy residue, and refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. The term “light hydrocarbon liquid” is intended to include liquid hydrocarbons that have a carbon chain of Cl to C6, (e.g., methane, ethane, propane, butane (n-butane, i-butane), pentane, and hexane). A complex liquid hydrocarbon mixture includes but is not limited to any hydrocarbon liquid streams derived from the refining of crude oil such as naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil and heavy residue. Sour liquid hydrocarbons are typically produced along with natural gas (where they are referred to as natural gas liquids, or NGLs) or generally with species that at atmospheric pressure are gases, but condense when pressurized (hydrocarbon gas liquids, or HGLs).

[0018] Impurities intended to be removed from sour liquid or hydrocarbon liquid using the liquid-liquid reactive absorber of the disclosure can include but are not limited to hydrogen sulfide, sulfur, mercaptans, thioethers, sulfur odorants, sulfide compounds, thiol compounds, and other sulfur containing impurities entrained in the hydrocarbon liquid.

[0019] A liquid-liquid reactive absorber is comprised of, or consists of, a liquid contacting reactor (e.g., a vessel, such as but not limited to column reactor, a mixer-settler system or a centrifugal contactor) filled with an aqueous mixture of hydriodic acid and iodine. In one embodiment, the hydriodic acid concentration is up to its azeotrope of about 57 wgt%. In other embodiments, the hydriodic acid concentration is slightly higher than the azeotropic concentration, such as about 57 wgt% to about 62 wgt %. In yet another embodiment, the hydriodic acid concentration can be from about 5 wgt% to about 62 wgt %. Into this vessel is fed a hydrocarbon liquid containing dissolved hydrogen sulfide and / or sulfur entrained into a complex hydrocarbon mixture as, for example a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds. As the hydrocarbon liquid moves through the vessel, the hydrogen sulfide originally dissolved in the liquid or hydrocarbon species with entrained sulfur atoms from liquid streams reacts with the iodine to produce sulfur dioxide and hydriodic acid. The immiscible hydrocarbon and aqueous mixture phases separate with the hydrocarbon forming a layer on top. This top layer is skimmed off to produce a sweet hydrocarbon (a hydrocarbon in which the sulfur components have been removed) due to its lower density, while the larger volume aqueous mixture on the bottom is also slowly removed, regenerated, and replaced. An outlet is placed at the bottom of the liquid-liquid reactive absorber, where the rich aqueous solution exits the reactive absorber and is transferred to the downstream reactor. Inthe downstream reactor, hydrogen and iodine can be generated from hydriodic acid produced in the reaction. The produced iodine can be transferred back to the reactive absorber to react with sour liquid or hydrocarbon liquid.

[0020] The reaction of H2S with I2 is thermodynamically favorable, exothermic, with mass-transfer limited kinetics (Ryan J. Gillis, Phalgun Lolur, and William H. Green, ACS Sustainable Chemistry & Engineering 2019 7 (7), 7369-7377), the teachings of which are incorporated herein by reference in their entirety. The reaction of dissolved hydrogen sulfide proceeds according to the following stoichiometry:H2S + 312 + 2 H2O 6HI + SO2 [1]

[0021] Iodine (I2) will also react with water to oxidize sulfur entrained within complex hydrocarbon molecules such as R-SH, called thiol compounds, sulfhydryl compounds, or sulfanyl compounds, and R-S-R, called organic sulfide or thioether, liberating the sulfur as sulfur dioxide (SO2) and producing hydriodic acid (HI). Simply this behavior can be thought of as proceeding according to the following stoichiometry:R-SH + 212 + 2H2O RH + 4HI + SO2 [2]R-S-R + I2 + 2H2O 2RH + 2HI + SO2 [3] where R represents the remaining complex hydrocarbon molecule.

[0022] An aqueous rich solution comprising or consisting of hydriodic acid and SO2 exits at the bottom of the liquid-liquid reactor of the disclosure through an outlet. Further thermochemical processing of the aqueous rich solution is carried out in a processing unit, as described for example in US20200369518. The contact between the hydriodic acid solution and the hydrocarbon liquids 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), a Mixer-settler system, a centrifugal contactor, or a pulse column.

[0023] In one embodiment is disclosed a method of removing entrained sulfur from complex liquid hydrocarbon mixtures, as discussed herein, through the oxidation of entrained sulfur atoms (in the form of a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds) to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid, using the liquid-liquid reactive absorber of the disclosure. Downstream processing of the aqueous rich solution from the liquid-liquid reactive absorber can be performed to generate hydrogen from the hydriodic acid produced in the reaction. In an aspect of this embodiment, the sulfur is hydrogen sulfide.

[0024] In another embodiment is disclosed a method of removing dissolved hydrogen sulfide from a liquid mixture through its oxidation to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid, using the liquid-liquid reactive absorber of the disclosure. Downstream processing of the aqueous rich solution from the liquid-liquid reactive absorber can be performed to generate hydrogen from the hydriodic acid produced in the reaction. In an aspect of this embodiment, the liquid mixture is a liquid hydrocarbon.

[0025] In yet another embodiment is disclosed a method of generating hydrogen from hydriodic acid produced from the reaction of complex liquid hydrocarbon mixtures with entrained sulfur atoms (in the form of a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds) with mixtures containing water, iodine, and hydriodic acid.

[0026] With reference to the Figure, a sour liquid (or sour hydrocarbon) enters a liquidliquid reactive absorber (1) through an inlet (2) and mixes with an aqueous mixture of hydriodic acid and iodine contained within. As the sour liquid moves through the liquidliquid reactive absorber (1), the hydrogen sulfide originally dissolved in the liquid or hydrocarbon species with entrained sulfur atoms from liquid streams reacts with the iodine to produce sulfur dioxide and hydriodic acid. The immiscible hydrocarbon and aqueous mixture phases separate with the hydrocarbon forming a layer on top. This top layer is skimmed off to produce a sweet hydrocarbon (a hydrocarbon in which the sulfur components have been removed), which can be collected through outlet (3) on the top of the liquid-liquid reactive absorber. An aqueous rich solution comprising or consisting of hydriodic acid and SO2 exits at the bottom of the liquid-liquid reactor through a rich aqueous solution outlet (4). Regenerated aqueous solution can be returned to the liquid-liquid reactive absorber (1) through a lean aqueous solution inlet (5) coming from the downstream hydrogen production and solution regeneration process unit (9).

[0027] The liquid-liquid reactor absorber reactor can be operated in a wide range of temperatures, depending on the boiling point of the inlet hydrocarbon mixtures. For example, the boiling point of naphtha (C5-C12) is from about 50 °C to about 200 °C at the pressure of 1 bar. To maintain the hydrocarbon mixtures, which is naphtha in this case, the liquid-liquid reactor absorber reactor can be controlled to have temperature from about 50 °C to about 200 °C and pressure from 1 to 50 bars. For heavy hydrocarbon mixtures (such as C12 and above), higher operating temperatures can be given due to their higher boiling point ranges.

[0028] The present method has many advantages over previous designs in that it allows the extraction of hydrogen sulfide and sulfur from liquid-phase inlet streams. In oneembodiment, the system consists of a liquid inlet (2) entering the system at a flow rate of 10 GPM at a temperature of 80 °F (26.67 °C) and a pressure of 50 psia, with an atomic composition of 4% sulfur in a complex crude mixture. In this embodiment, the reactor (1) consists of a 1000-gallon vessel filled with 800 gallons of an aqueous mixture of 41 wgt% water, 55 wgt% hydriodic acid, and 4 wgt% iodine. The aqueous mixture is withdrawn from the bottom of the tank (4) at a rate of 2 GPM. This aqueous outlet is pumped (6) to a separate process and regenerated to form hydrogen and iodine in the separate process, as described for example in US20200369518, before being added back into the top of the vessel as an inlet stream (5) of the absorber reactor (1). The separate process can include heat exchangers (7) and (8), a hydrogen generation reactor (9), and vapor-liquid separation unit (10) and (11) to have vapor product streams of SO2 (12) and hydrogen (13).

[0029] 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.Definitions

[0030] 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.

[0031] 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.

[0032] 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 ”

[0033] 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.”

[0034] Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and synonyms and variants thereof such as “have” and “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.”

[0035] “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 theExamples. For example, an “about” azeotropic mixture of hydriodic acid and water will include 57 wgt% by weight (±10 %).

[0036] “Complex liquid hydrocarbon” is intended to mean any hydrocarbon liquid stream derived from the refining of crude oil such as naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil, and heavy petroleum or oil residue (such as a fluid byproduct created by refining crude oil into solid products). One important application is on liquid naphtha streams within a petroleum refinery. Liquid naphtha streams are defined by their boiling point ranges, but their composition can be complicated. All types of hydrocarbons such as Paraffins, Isoparaffins, Olefins, Naphthenes, Aromatics can exist in naphtha, with various compositions. Mixtures of complex liquid hydrocarbons are also intended by this definition.

[0037] “Complex liquid hydrocarbon” can also refer to refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. They are more refined than liquid naphtha; however, due to the different crude oil sources and different refinery processes, the composition of these refined products is complex and has no fixed values.

[0038] 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.

Claims

CLAIMSWhat is claimed is:

1. A method of removing entrained sulfur from liquid hydrocarbon through the oxidation of entrained sulfur atoms to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid.

2. A method of removing dissolved hydrogen sulfide from a liquid hydrocarbon through its oxidation to sulfur dioxide by a mixture that contains water, iodine, and hydriodic acid.

3. The method of claim 1 or claim 2, wherein hydrogen is generated from hydriodic acid produced from the reaction of dissolved hydrogen sulfide with mixtures containing water, iodine, and hydriodic acid.

4. A method of generating hydrogen from hydriodic acid produced from the reaction of liquid hydrocarbon with entrained sulfur atoms with mixtures containing water, iodine, and hydriodic acid.

5. The method of claim 1, 3 or 4, wherein the entrained sulfur atom can be in the form of a mercaptan end, a thioether coupling, or other sulfur containing subunit such as sulfide compounds and thiol compounds.

6. The method of any one of clams 1-4, wherein the liquid hydrocarbon is selected from refining of crude oil, such as naphtha, kerosene, diesel distillate, atmospheric gas oil, vacuum gas oil, and heavy petroleum or oil residue.

7. The method of any one of claims 1-4, wherein the liquid hydrocarbon is liquid naphtha.

8. The method of any one of claims 1-4, wherein the liquid hydrocarbon is gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils.

9. The method of claim 1, 3 or 4, wherein the entrained sulfur is present in a liquid hydrocarbon selected from paraffins, isoparaffins, olefins, naphthenes, or aromatics.

10. A liquid-liquid reactive absorber comprising a liquid contacting reactor, a mixture containing water, iodine and hydriodic acid in intimate contact with a sulfur containing liquid, within the liquid contacting reactor.

11. The liquid-liquid reactive absorber of claim 10, wherein the liquid contacting reactor is comprised of a column reactor.

12. The liquid-liquid reactive absorber of claim 10, wherein the liquid contacting reactor is comprised of a mixer- settler system.

13. The liquid-liquid reactive absorber of claim 10, wherein the liquid contacting reactor is comprised of a centrifugal contactor.

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