WO2023107485A1

WO2023107485A1 - Treatment compositions and methods of using same for remediating mercaptans and other sulfur-containing compositions in hydrocarbon based liquids

Info

Publication number: WO2023107485A1
Application number: PCT/US2022/052001
Authority: WO
Inventors: Cliffton Roe
Original assignee: Gaps Technology, Llc
Priority date: 2021-12-09
Filing date: 2022-12-06
Publication date: 2023-06-15

Abstract

A treatment composition for remediating and removing mercaptans from contaminated hydrocarbon based liquids, the treatment composition including a hydrocarbon based liquid, at least one hydroxide compound and a chelating agent. A collective content of the at least one hydroxide compound in the treatment solution is in a range of 1 to 10 weight %, a content of the chelating agent in the treatment solution is 0.1 to 2 weight %, and a content of the hydrocarbon based liquid in the treatment solution is 85 to 98.9 weight %.

Description

RCL-121-P-PCT

TREATMENT COMPOSITIONS AND METHODS OF USING SAME FOR REMEDIATING MERCAPTANS AND OTHER SULFUR-CONTAINING COMPOSITIONS IN HYDROCARBON BASED LIQUIDS

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

[0001] The present disclosure relates to novel treatment compositions and treatment methods for remediating sulfur-containing contaminants such as mercaptans, which are also known as thioalcohols, and other similar contaminants from hydrocarbon based liquids such as crude oil and liquids obtained by refining crude oil. More particularly, the present disclosure relates to such novel treatment compositions and treatment methods using the compositions in which the contaminants such as mercaptans are disassociated into sulfur, organic substances, etc. and which may then be easily removed from the treated hydrocarbon based liquids in an efficient and economically practical manner.

2. BACKGROUND

[0002] Sulfur-containing compounds including hydrogen sulfide (H2S), mercaptans, thiophenes and BTEX have long been recognized as undesirable contaminants in contaminated fluids, particularly in hydrocarbon fluids such as crude oil and natural gas. H2S is a particularly undesirable contaminant because it is highly toxic, corrosive, etc. and generally hydrocarbon fluids should contain less than five ppm H₂S. However, even when there is little H2S in a given hydrocarbon liquid, the liquid may contain significant amounts of other sulfur-containing contaminants such as mercaptans and thiophenes which must be remediated down to acceptable levels to make the hydrocarbon liquid more valuable and usable.

[0003] Mercaptans are complex organic molecules having a general formula R-S-H in which sulfur is bound to a solvent, alcohol or other organic substances commonly referred to as aromatic compounds which may have a relatively high vapor pressure. There are many known species of mercaptans, which are also known as thioalcohols, including amyl mercaptan, butyl mercaptan, methyl mercaptan, ethyl mercaptan, phenyl mercaptan and cyclohexyl mercaptan to name a few. Mercaptans are often present in the matrix of substances typically found in crude oil with a slightly acidic pH of 5.8 to 6.2 and may be released from the crude oil as acidic gases or vapors. These acid gasses are highly corrosive to the metallic infrastructure and raise great safety concerns so that the acidic gasses containing the mercaptans must be removed or otherwise controlled, e.g., by containing, venting and scrubbing the acidic gasses from the vented gasses and vapors before the gasses and vapors are released into the atmosphere.

[0004] Mercaptans cannot be removed by distillation or amine treatment, but for liquids such as crude oil there are two conventional treatment options for treating mercaptans respectively known as extraction and sweetening, each of which involves oxidizing the mercaptans into disulfides. In a conventional extraction treatment, after the mercaptans have been oxidized into disulfides the disulfides are dissolved or extracted into an aqueous based caustic solution and thereby removed from the crude oil or other hydrocarbon based liquid being treated. Subsequently the disulfides may be precipitated and removed from the caustic solution, and the caustic solution may then be reused. In a conventional sweetening treatment, the mercaptans that have been oxidized into disulfides are left in the treated liquids. Extraction is typically used for lighter hydrocarbon products such as light naphtha and sweetening is typically used for heavier hydrocarbon products such as gasoline and diesel fuel. The conventional treatment processes are generally effective for remediating and possibly removing mercaptans from crude oil and other liquids, but the conventional processes remain to be improved on in terms of effectiveness and cost efficiency.

[0005] The present inventor has previously proposed treatment compositions and treatment processes for removing H₂S and other contaminants from contaminated Liquids such as crude oil and so-called produced water” that is highly contaminated water that is extracted together with crude oil and natural gas from the earth. See, for example, those treatment compositions and treatment processes disclosed in International Patent Application Nos.

PCT/US2018/050913 and PCT/US2018/064015, and in US Patent No. 10,913,911 B2. The entire contents of these prior disclosures are incorporated herein by reference. These previously disclosed treatment compositions are aqueous based compositions primarily involving high concentrations, such as 35-55 wt % collectively, of one or more hydroxide compounds. When the previously proposed treatment compositions are added to or otherwise contacted with the contaminated fluids in the treatment processes, the highly concentrated hydroxide compound(s) are very effective at quickly remediating IfeS down to safe, acceptable levels. The previously proposed treatment compositions may also include a small amount, such as 0.1 to 4 wt %, of one or more organic acids such as fulvic acid and humic acid, which are very effective for preventing substances that are formed from the remediated H2S, as well as other contaminants, from precipitating out of the treated fluids. Preventing formation and release of precipitates can be very important because such precipitants can cause clogging and other significant problems for the treatment systems that must be addressed, resulting in reduced efficiency and added cost. [0006] However, the inventor’s previously proposed treatment compositions and treatment methods are not very effective at directly removing or remediating mercaptans from hydrocarbon based liquids such as crude oil and liquids obtained from refined crude oil. This lack of direct effectiveness may be due, at least in part, to the fact that the mercaptans are organic based molecules, whereas the previously proposed treatment compositions are aqueous based. [0007] Hence, it still remains a great challenge in the art for quickly remediating mercaptans in contaminated hydrocarbon based liquids down to appropriate, safe levels in a practical, cost effective manner.

SUMMARY AND DETAILED DESCRIPTION OF THE INVENTION

[0008] The present inventor has carefully studied the treatment of hydrocarbon based liquids containing relatively high concentrations of mercaptans, and has discovered new treatment compositions and treatment processes which are very effective, efficient and economically practical for quickly remediating and/or removing most of the mercaptans in such hydrocarbon based liquids down to safe, acceptable levels in an efficient, cost-effective manner.

[0009] One discovery made by the present inventor is a new organic liquid based treatment composition which includes little or no waler and is effective at breaking down the mercaptans such that the sulfur is separated from the solvent, alcohol or other organic / aromatic substances to which the sulfur is bound in the mercaptans. The new treatment composition includes at least one organic liquid as a base, unlike the inventor’s previously proposed treatment compositions which are aqueous based solutions, together with one or more hydroxide compounds and possibly a chelating agent. [0010] A wide variety of polar and non-polar hydrocarbon based liquids may be used in the new treatment compositions, including relatively light liquid(s) including alcohols, toluene, hexane, xylene, and others, as well as mixtures of these liquids, provided that the hydroxide compound(s) and any other components to be included in the treatment compositions may be fully dissolved or dispersed into the hydrocarbon based liquids. Alcohols are appropriate for use as the hydrocarbon liquids because they are polar so that other components of the treatment composition(s) are generally dissolvable and/or miscible therein. Lighter alcohols, including methanol (CH3OH), ethanol (C2H5OH), and n-propyl alcohol (CsHgO), may be more appropriate based on lower cost and/or higher vapor pressure. Toluene, hexane, xylene, and other similar organic liquids are also appropriate as the hydrocarbon liquids used in the treatment compositions according to the present invention because the hydroxide compounds and other components are dissolvable or dispersible therein. Also, these liquids have relatively high vapor pressures which is desirable because more of the reactive hydroxide compound(s) may be contained in the vapors where they can better react with gaseous contaminants including H2S and CO₂.

[0011] A collective content of the at least one hydroxide compound in the treatment composition may be in a range of 1 to 10 weight % and content of a chelating agent such as ethylenediamine tetraacetic acid (EDTA) and a content of the chelating agent in the treatment composition may be 0.1 to 2 weight %. Thus, a content of the hydrocarbon based liquid in the treatment solution may be 85 to 98.9 weight %. Generally, the new treatment composition should include less than 3 wt% water, and preferably less than 1% water. It is desirable that other components of the new treatment composition should be dissolvable and/or miscible in the hydrocarbon base liquid used in the composition. The new treatment composition is effective for remediating mercaptans in hydrocarbon based liquids at standard temperature and pressure, but the remediation reaction(s) proceed more quickly at elevated temperatures. After the mercaptans are remediated into other components, the other components may then be removed from the contaminated crude oil or other hydrocarbon based liquid being treated if desired.

[0012] Generally, all hydroxide compounds may be used provided they can be dissolved or dispersed in the hydrocarbon liquid(s) of the all composition. Some typical hydroxide compounds that may be used in the new treatment compositions include sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), magnesium hydroxide ( Mg(OH ) ₂ , manganese hydroxide (Mn(OH) ₂ , Mn(OH)₄) and ammonium hydroxide (NH4OH). However, some hydroxide compounds have lower cost, e.g., NaOH and KOH, and if used may make the composition and treatment processes using the composition more economically advantageous. Also, if the treatment composition is to be used with fluids such as crude oil and/or natural gas which include significant amounts of NaCl, which will typically be dissolved in any water included in the fluids, it may be desirable to use little or no NaOH to help prevent causing any salt to precipi tate out of the heated fluids. It is important that components of the composition other than the hydrocarbon liquid(s) should be dissolvable, dispersable and/or miscible in the hydrocarbon based liquid(s) used in the treatment composition.

[0013] According to an exemplary embodiment of the present invention, the new treatment composition may be prepared by combining one liter of methanol (CH₃OH) or other organic liquid, 20 to 30 grams collectively of one or more hydroxide compounds and 0.2 to 1.0 gram of a chelating agent such as EDTA. This exemplary treatment composition has a pH of over 10. The hydroxide compound(s) may be in the form of a hydrate such as KOH hydrate or NaOH hydrate, which are solid materials that readily dissolve in the methanol and other alcohols, while the EDTA may also be in the form of a solid or powder that also readily dissolves in the methanol. Even though the new treatment composition should contain little or no water, due to the relatively small amount of EDTA being used, it may be used in the form of a concentrated aqueous solution containing 30-50 wt% EDTA, rather than as a solid or powder, because the small amount of water contained therewith will not reduce the effectiveness of the treatment composition at remediating the mercaptans in the crude oil or other hydrocarbon based liquid being treated.

[0014] As an exemplary treatment process for remediating and/or removing mercaptans from crude oil, liquids from crude oil that has been partly refined, or other hydrocarbon based liquid being treated, the inventor has found that when a relatively small amount, e.g., 5-25 ml, of such treatment composition is added / liter of the contaminated hydrocarbon liquid being treated and the mixture is heated to about 190 to 250 °F or 87.8 to 121.11°C for 15 to 180 minutes while the mixture is stirred or mixed at ambient pressure under an oxygen-containing gas such as air, this is effective for remediating much, e.g., at least 70% reduction, of the mercaptans from the crude oil or other hydrocarbon based liquid being treated. The remediation of the mercaptans by the treatment composition involves displacing the solvent, alcohol or other organic / aromatic substances that are bound to the sulfur in the mercaptans. Once the treatment composition has reacted with the mercaptans such that the solvent, alcohol or other organic / aromatic substances are displaced from the sulfur in the mercaptans, these organic liquids will mostly be released as vapors from the treated hydrocarbon liquid. Such vapors may then be collected, e.g., in a headspace of a reaction chamber in which the treatment process is carried out, and then the collected vapors may be vented off for further treatment or recovery. On the other hand, the sulfur that is released from the remediated mercaptans is mostly, e.g., typically 95% or more, converted into sulfur dioxide (SO2) which is also released from the treated hydrocarbon liquid as a gas and may also be vented off for further treatment or recovery. The inventor is not fully clear on how and why the sulfur released from the mercaptans is converted into sulfur dioxide in the remediation process, but the treatment process is carried out under an oxygen-containing atmosphere, e.g., ambient air, and treated liquid is being heated at 190 to 210 °F or 87.8 to 98.9 °C for 10 to 60 minutes during the treatment process. A small percentage of the sulfur that is released from the remediated mercaptans may remain in the treated hydrocarbon liquid.

[0015] For the treatment process, the inventor has further discovered that the effectiveness of the new treatment composition may be increased if a small amount of a concentrated acid is initially added as a pre-treatment to the contaminated hydrocarbon liquid being treated prior to adding the new treatment composition. Essentially any acid may be used, but hydrochloric acid (HC1), sulfuric acid (H2SO4), and nitric acid (HNO3) are appropriate and available at reasonable cost. Acids are typically provided in the form of aqueous based solutions at various concentrations, but because the treatment process according to the present invention should involve as little water as possible, it is preferred that highly concentrated acids be used in the treatment process. For example, 0.5 - 5.0 ml of 12 M (37 wt %) hydrochloric acid (HC1) may be added / liter of contaminated hydrocarbon liquid. Although the acid contains about 60 wt% water, the amount of water is sufficiently small that it does not inhibit the effectiveness of the new hydrocarbon liquid based treatment composition at remediating the mercaptans in the crude oil or other hydrocarbon based liquid. The acid lowers the pH of the contaminated hydrocarbon liquid slightly, e.g., by about 0.5. For example, if the original pH of the contaminated crude oil or other liquid was 6.0, the acid may lower the pH to about 5.5. Such llduction of the pH helps to expose some of the different mercaptan species in the crude oil or other hydrocarbon liquid being treated so that the new treatment composition may more fully react with the exposed mercaptans and break them down into sulfur and the solvent, alcohol or other organic / aromatic substances bonded to the sulfur in the mercaptans. As an exemplary treatment step, the HC1 may be initially mixed into the crude oil or other hydrocarbon based liquid being treated, and the mixture may be heated, e.g., at 190 to 230 °F or 87.8 to 110 °C for 10 to 120 minutes. The inventor has discovered that by initially adding the acid to the liquid being treated, the acid itself does not remediate the mercaptans, but is effective to expose some of the mercaptans so that they may react with the treatment composition, and thereby increases the measurable amount of mercaptans in the liquid being treated. Through the pre-treatment with acid, a greater amount of the mercaptans may be remediated and/or removed from the contaminated liquids by the new treatment composition when the treatment composition is subsequently added to the liquid being treated.

[0016] In two actual examples of the treatment process according to an embodiment of the present invention two different contaminated liquids obtained by refining crude oil were used, one of which was a C5 fraction. The initial measured amounts of mercaptans in neat or raw samples of the liquids being treated were respectively 461.066 mg/kg and 433.130 mg/kg. After 1.0 m l of 12 M HC was mixed into 500 ml samples of the contaminated liquid samples and the mixture was heated to about 200 °F / 93.3 °C for 60 minutes, the measured mount of mercaptans in the acid pre-treated samples increased respectively to 524.582 mg/kg and 536.300 mg/kg. Hence, through the acid pre-treatment the measurable amounts of mercaptans in the samples respectively increased by 11.7% and 23.8%.

[0017] After the acid pre-treatment, 10 ml of the new treatment composition according to an embodiment of the present invention was mixed into each sample, which treatment composition was prepared by combining one liter of methanol (CH₃OH), 23 grams of potassium hydroxide hydrate and 0.5 ml of an aqueous solution containing 40 wt% EDTA. The first sample mixture was heated to 213 °F / 100.56 °C and stirred for 90 minutes, and the second sample mixture was heated to 220 °F / 104.44 °C and stirred for 90 minutes. After such treatment, the content of mercaptans in the first sample was reduced to 114.816 mg/kg or 75.10% reduction and the content of mercaptans in the second sample was reduced to 74.145 mg/kg or 82.68% reduction.

[0018] The inventor has also discovered that once the pre-treatment acid and the new treatment composition have reacted with the mercaptans in the contaminated hydrocarbon liquid being treated, a small amount, e.g., 1-12 ml of one of the inventor’s previously proposed, aqueous based treatment compositions as disclosed in PCT/US2018/064015, and in US Patent No. 10,913,911 and variations thereof may be added per liter of the treated hydrocarbon liquid for further reducing the amount of mercaptans in the treated hydrocarbon liquids down to appropriate, safe levels such as less than 5 ppm. In the two actual examples mentioned above, after the acid pre-treatment and the treatment with the new treatment composition were completed, 3 ml of a treatment composition as disclosed in PCT/US2018/064015 was added to each same while the samples were respectively heated at 195 °F/90.56 °C and 224 °F/106.67 °C and the treated liquid samples were allowed to cool down for 30 minutes. The specific treatment composition was aqueous based and included 50 wt% collectively of a mixture of NaOH and KOH, and about 0.5 wt% of fulvic acid. The samples were again measured for mercaptan content, and the measurements showed that the first sample content was reduced to 14.874 mg/kg or 96.77 % reduction compared to the neat sample and the second sample content was reduced to 11.063 mg/kg or 97.44 % reduction compared to the neat sample. Table 1 below more completely shows the results of the two treated samples.

Table 1

Intent of Disclosure

[0019] Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid in understanding of the invention, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how it may later be disguised by variations in form or additions of further improvements. The claims at the end hereof are the chief aid toward this purpose, as it is these that meet the requirement of pointing out the improvements, combinations and methods in which the inventive concepts are found.

[0020] The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the invention may be apparent to those having ordinary skill in the art and are encompassed by the claims appended hereto. As one example, while the new treatment compositions according to the present invention do not require the use of organic acids such as fulvic acid and humic acid, a small collective amount, e.g., 0.1 to 2 weight %., of one or both of these organic acids may be included in the new treatment compositions in order to further prevent formation and release of any precipitates from the treated liquids.

Claims

I claim:

1. A treatment composition for remediating and removing mercaptans from contaminated hydrocarbon based liquids, the treatment composition comprising: a hydrocarbon based liquid: at least one hydroxide compound; and a chelating agent.

2. The treatment composition according to claim 1, wherein a collective content of the at least one hydroxide compound in the treatment solution is in a range of 1 to 10 weight %, a content of the chelating agent in the treatment solution is 0.1 to 2 weight %, and a content of the hydrocarbon based liquid in the treatment solution is 85 to 98.9 weight %.

3. The treatment composition according to claim 2, wherein the at least one hydroxide compound includes at least one of sodium hydroxide and potassium hydroxide.

4. The treatment composition according to claim 1, wherein the treatment composition contains less than 3 wt% water.

5. The treatment composition according to claim 1, wherein the hydrocarbon based liquid includes at least one of an alcohol, toluene, hexane, xylene.

6. The treatment composition according to claim 1, wherein the chelating agent is ethylenediamine tetraacetic acid (EDTA).

7. The treatment composition according to claim 1, wherein the treatment composition has a pH of about 10.

8. A treatment process for remediating and/or removing mercaptans from contaminated hydrocarbon based liquids, comprising steps of: Preparing a treatment composition including a hydrocarbon based liquid, at least one hydroxide compound and a chelating agent, mixing the treatment composition according to claim 1 into a contaminated hydrocarbon liquid containing mercaptans at a dosage rate of 5-25 ml of the treatment composition per liter of the contaminated hydrocarbon liquid: heating the mixture to a temperature in a range of 87.8 to 121.11 °C; and allowing the mixture to react.

9. The treatment process according to claim 8, wherein a collective content of the at least one hydroxide compound in the treatment solution is in a range of 1 to 10 weight %, a content of the chelating agent in the treatment solution is 0.1 to 2 weight %, and a content of the hydrocarbon based liquid in the treatment solution is 85 to 98.9 weight %.

10. The treatment process according to claim 8, wherein the treatment composition contains less than 3 wt% water.

11. The treatment process according to claim 8, wherein the reacting step involves allowed the mixture to react for 15 to 180 minutes while the mixture is mixed under an atmosphere containing an oxygen-containing gas.

12. The treatment process according to claim 8, comprising additional steps performed prior to the step of mixing the treatment composition into the contaminated hydrocarbon liquid, the additional steps including: adding a concentrated acid to the contaminated hydrocarbon liquid at a dosage rate of 0.5 - 5.0 ml of the concentrated acid per liter of the contaminated hydrocarbon liquid; heating the contaminated hydrocarbon liquid and the added acid to a temperature in a range of 87.8 to 110 °C; and allowing the mixture to react for 10 to 120 minutes.

13. The treatment process according to claim 12, wherein the acid is 12M hydrochloric acid (HQ).

14. The treatment process according to claim 8, comprising additional steps performed after to the step of allowing the treatment composition to react with the contaminated hydrocarbon liquid, the additional steps including: adding 1 to 12 ml of an aqueous based treatment composition per liter of the contaminated hydrocarbon liquid; heating the contaminated hydrocarbon liquid and the added aqueous based treatment composition to a temperature in a range of 87.8 to 121.11°C; and allowing the mixture to react for 10 to 60 minutes, wherein the aqueous based treatment composition includes at least one hydroxide compound, at least one organic acid selected from a group consisting of a fulvic acid and a humic acid, and water, wherein a collective concentration of the at least one hydroxide compound in the treatment solution is in a range of 35 - 55 weight %, a content of water in the treatment solution is at least 30 weight %, and a collective concentration of the at least one organic acid in the treatment solution is in a range of 0.01 to 2.0 weight %, and the aqueous based treatment solution has a pH of at least 13.

15. The treatment process according to claim 14, wherein the aqueous based treatment composition includes 0.1 to 5 wt% EDTA.

16. The treatment process according to claim 12, comprising additional steps performed after to the step of allowing the treatment composition to react with the contaminated hydrocarbon liquid, the additional steps including: adding 1 to 12 ml of an aqueous based treatment composition per liter of the contaminated hydrocarbon liquid; heating the contaminated hydrocarbon liquid and the added aqueous based treatment composition to a temperature in a range of 87.8 to 121.11°C; and allowing the mixture to react for 10 to 60 minutes, wherein the aqueous based treatment composition includes at least one hydroxide compound, at least one organic acid selected from a group consisting of a fulvic acid and a humic acid, and water, wherein a collective concentration of the at least one hydroxide compound in the treatment solution is in a range of 35 - 55 weight %, a content of water in the treatment solution is at least 30 weight %, and a collective concentration of the at least one organic acid in the treatment solution is in a range of 0.01 to 2.0 weight %, and the aqueous based treatment solution has a pH of at least 13.

17. The treatment process according to claim 16, wherein the aqueous based treatment composition includes 0.1 to 5 wt% EDTA.