Phosphorus-free, oil-soluble molybdenum complex for high-temperature naphthenic acid corrosion inhibition

Abstract

Sulfur-containing molybdenum complexes for use in compositions and methods for inhibiting or reducing high-temperature corrosion in oil refineries are disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 058,010, filed on July 29, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This application is aimed at inhibiting high temperature corrosion. Background Art

[0004] High temperature corrosion (e.g., 175°C to 600°C) is a well-known problem in the processing and refining of crude oil and related fractions. Oil acidity, primarily caused by high naphthenic acid levels, increases the corrosion problem, as does the presence of sulfur in the crude oil, which produces hydrogen sulfide or reactive sulfur species at higher temperatures.

[0005] Refineries processing high-acid crudes use advances in metallurgy to address corrosion, while other refineries use corrosion inhibitors from various chemical groups to prevent or reduce corrosion and its attendant adverse effects.

[0006] However, these options are not without their problems. Thus, there is a continuing need for corrosion inhibition compositions and methods that are effective and minimize operating costs, particularly for naphthenic acids and active sulfur species at high temperatures. There is also a need for corrosion inhibitors with reduced or no phosphorus. Phosphorus-containing complexes are known to impair the function of various catalysts used in crude oil processing. Summary of the Invention

[0007] Described herein are compositions and methods for inhibiting high temperature corrosion in a fluid source comprising a corrosive agent and at least a liquid hydrocarbon.

[0008] In one aspect of the present application is a method of inhibiting corrosion, comprising:

[0009] A sulfur-containing molybdenum complex having a general formula selected from Formula I or II is introduced into a fluid source containing a corrosive agent:

[0010]

[0011] wherein R represents an oxygen-, nitrogen- or carbon-containing compound, such as an alcohol, an alkyl group, an alkenyl group, an amide, an amine group or an aryl group; and n is 4 to 10.

[0012]

[0013] R and R' each represent an oxygen, nitrogen or carbon containing compound such as an alcohol, alkyl, alkenyl, amide, amine or aryl; and X represents oxygen or sulfur and may be the same or different, but wherein at least one X in the formula is sulfur.

[0014] In one aspect of the present application is a composition comprising:

[0015] A sulfur-containing molybdenum complex is provided to inhibit corrosion in a fluid source containing a corrosive agent and in contact with a metal containment vessel, the sulfur-containing molybdenum complex comprising a formula selected from Formula I or II:

[0016]

[0017] wherein R represents an oxygen-, nitrogen- or carbon-containing compound, such as an alcohol, an alkyl group, an alkenyl group, an amide, an amine group or an aryl group; and n is 4 to 10.

[0018]

[0019] R and R' each represent an oxygen, nitrogen or carbon containing compound such as an alcohol, alkyl, alkenyl, amide, amine or aryl; and X represents oxygen or sulfur and may be the same or different, but wherein at least one X in the formula is sulfur.

[0020] Yet another aspect of the present application is a treated metal containment vessel comprising: a metal containment vessel comprising a metal surface; and a fluid source comprising a sulfur-containing molybdenum complex as described in Formulas I, II, II, and IV, wherein at least a portion of the metal surface is in contact with the fluid source.

[0021] Sulfur-containing molybdenum complexes are used to inhibit corrosion of metal containment vessels containing a fluid source containing one or more corrosive agents, particularly corrosive agents with high acidity and in processes involving high temperatures (e.g., 175° C. to 600° C.). DETAILED DESCRIPTION

[0022] Although the present disclosure provides reference to various embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the present disclosure. Various embodiments will be described in detail with reference to the accompanying drawings. Reference to various embodiments does not limit the scope of the claims appended hereto. In addition, any examples set forth in this specification are not intended to limit and to illustrate only some of the many possible embodiments of the appended claims.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those of ordinary skill in the art. In the event of a conflict, this document (including definitions) shall prevail. Methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used to practice or test various embodiments of this specification. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety.

[0024] As used herein, the term "corrosive agent" is a material that causes, initiates, catalyzes, accelerates, induces, or otherwise promotes the corrosion of metals.

[0025] As used herein, the term "corrosion inhibitor" (CI) means a complex or mixture that prevents, retards, mitigates, reduces, controls, and / or delays corrosion.

[0026] As used herein, the term "fluid source" means any source of fluid containing one or more corrosive agents used in operations in the petroleum industry (ie, petroleum transportation, storage, and refining).

[0027] As used herein, the terms "inhibits," "inhibiting," or grammatical equivalents thereof, refer to preventing, retarding, mitigating, reducing, controlling, and / or delaying corrosion.

[0028] The term "naphthenic acid," as used in conjunction with corrosion, refers to one or more monocyclic or bicyclic carboxylic acids with a boiling range between 176°C (350°F) and 343°C (650°F). During crude oil distillation, these acids tend to concentrate in the heavier fractions. Naphthenic acid is a general term for certain organic acids found in various crude oils. While other organic acids may be present in trace amounts, it is understood that most acids in naphthenic crude oils have the characteristics of cycloalkanes, i.e., having saturated, unsaturated, or aliphatic ring structures, as shown below:

[0029]

[0030] As used herein, the term "passivation" means preventing a reaction between two materials when the two materials are used together by coating at least one of the two materials to an extent that their reactivity relative to each other is substantially reduced.

[0031] As used herein, the terms "comprise," "including," "have," "having," "may," "contain," and variations thereof are intended to be open-ended transitional phrases, terms, or words that do not exclude the possibility of additional actions or structures. Unless the context clearly dictates otherwise, the singular forms "a," "an," "and," and "the" include plural references. The present disclosure also encompasses other embodiments that "comprise," "consist of," and "consist essentially of" embodiments or elements set forth herein, whether explicitly stated or not.

[0032] As used herein, the terms "optional" or "optionally" means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0033] As used herein, the term "about" used in describing the embodiments of the present disclosure to modify, for example, various ingredients, concentrations, volumes, process temperatures, process times, yields, flow rates, pressures, and similar values ​​in the compositions, as well as ranges thereof, refers to variations in numerical quantities that may occur, for example, due to typical measurement and handling procedures for preparing complexes, compositions, concentrates, or using the formulations; due to inadvertent errors in these procedures; due to differences in the manufacture, origin, or purity of the starting materials or ingredients used to perform the methods, and similar considerations. The term "about" also encompasses amounts that vary from a specific starting concentration or mixture due to aging of the formulation, as well as amounts that vary from a specific starting concentration or mixture due to mixing or processing of the formulation. Where modified by the term "about," the appended claims include equivalents to these amounts. In addition, where "about" is used to describe a range of values, for example, the statement "about 1 to 5" means "1 to 5" and "about 1 to about 5" and "1 to about 5" and "about 1 to 5," unless the context specifically limits otherwise.

[0034] As used herein, the term "substantially" means "consisting essentially of" and includes "consisting of." "Consisting essentially of" and "consisting of" are interpreted as per U.S. patent law. For example, a solution that is "substantially free of" a specified complex or material may contain no complex or material, or may contain trace amounts of the complex or material, such as due to undesirable contamination, side reactions, or incomplete purification. A "trace amount" may be a trace amount, an unmeasurable amount, an amount that does not interfere with a value or characteristic, or some other amount as provided in the context. A composition having "only substantially" a provided list of components may consist only of those components, or have trace amounts of some other components present, or have one or more additional components that do not substantially affect the properties of the composition. In addition, "substantially" modifying the type or amount of an ingredient in a composition, a property, a measurable amount, a method, a value, or a range, for example, as employed in describing the embodiments of the present disclosure, refers to a modification that does not affect the overall composition, property, amount, method, value, or range in a manner that invalidates the intended composition, property, amount, method, value, or range. The following claims where modified by the term "substantially" include equivalents according to this definition.

[0035] As used herein, any stated range of values ​​encompasses all values ​​within the stated range and should be interpreted as supporting claims reciting any sub-range having endpoints with real values ​​within the stated range. By way of example, the disclosure of a range of 1 to 5 in this specification should be considered supporting claims in any of the following ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5, and any values ​​therebetween.

[0036] Compositions and methods are described for inhibiting corrosion in hydrocarbon fluid sources that are formed during crude oil refining processes, particularly those formed by processing and refining oil at temperatures ranging from about 175°C to about 600°C and that have corrosive agents. The acidity can be due to the presence of naphthenic acids, sulfur compounds, or both. In the presence of naphthenic acids, sulfur, at high temperatures, or a combination thereof, corrosion is extremely aggressive and difficult to inhibit.

[0037] The compositions can be applied to one or more liquid hydrocarbon products to inhibit or reduce corrosion in oil transportation, storage, and refining equipment such as pipes, pipelines, valves, and the like. The corrosion inhibiting composition comprises at least one sulfur-containing molybdenum complex. The sulfur-containing molybdenum complex contains at least one molybdenum center coordinated to sulfur, an oxygen-containing ligand, a mercaptan, a sulfide, a thiocarbamate, a thiocarbonate, a thioacid, or a polymer thereof, and combinations thereof. In some embodiments, the sulfur-containing molybdenum complex is a metal-containing complex. The compositions and methods described inhibit corrosion by acting as a corrosion inhibitor, or passivate a surface to resist corrosion, or both.

[0038] In some embodiments, the sulfur-containing molybdenum complex has the general formula of Formula I or Formula II.

[0039]

[0040] wherein Mo is a molybdenum complex, S is sulfur, R represents an oxygen-, nitrogen- or carbon-containing ligand, such as an alcohol, an alkyl, an alkenyl, an amide, an amine or an aryl; and n is 2-10 or 4-10 or 2-6.

[0041]

[0042] wherein R and R' each represent an oxygen-, nitrogen-, or carbon-containing ligand, such as an alcohol, an alkyl, an alkenyl, an amide, an amine, or an aryl group, and R and R' may be the same or different; and X represents oxygen or sulfur and may be the same or different, but wherein at least one X in the formula is sulfur.

[0043] In some embodiments, R or R' represents an alkyl group (straight chain, branched, and cyclic) with or without saturation or heteroatoms, or both; a thiol, a sulfide, a thiocarbamate, a thiocarbonate, a thioacid, an aromatic ring with or without substituents, an organic polysulfide, or an inorganic polysulfide.

[0044] In some embodiments, R and R' are each an alkyl or aryl group (including alkaryl) having 2 to 30 carbon atoms; 5 to 20 carbon atoms; 5 to 15 carbon atoms; 5 to 10 carbon atoms. In some embodiments, the above number of carbon atoms is characterized by one or more hydroxyl groups (e.g., alkyl alcohols), acids, or esters thereof. In some embodiments, the alkyl group is ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, cyclohexyl, phenyl, naphthyl, tolyl, xylyl, benzyl, and phenethyl. These alkyl groups may be primary, secondary, or tertiary alkyl groups and may be straight or branched. In some embodiments, (alkyl) aryl groups include phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, and dodecylphenyl, all of which may be primary, secondary, or tertiary alkyl groups and may be straight or branched. Furthermore, (alkyl)aryl includes all positional isomers, wherein the aryl group may have an alkyl substituent at any position. In some embodiments, the (alkyl)aryl group is composed of carbon and hydrogen and heteroatoms such as nitrogen, oxygen, and sulfur.

[0045] In some embodiments, the alcohol group can be a monosubstituted alcohol, a diol, or a bis-ol, or a polyol. In some embodiments, the alcohol has six to ten carbon atoms.

[0046] In some embodiments, the amino group may be a monoamine, a diamine, or a polyamine. In some embodiments, the amine is a dialkylamine having the formula HNR5R6, wherein R5 and R6 are each selected from a straight or branched chain containing 2 to 24 carbon atoms or 4-13; 8 to 13; or 10 to 20 carbon atoms. R5 may be the same as or different from R6. In some embodiments, R5 and R6 may be aryl groups including (alkyl)aryl groups. In some embodiments, the alkyl group is ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. These alkyl groups may be primary, secondary, or tertiary alkyl groups and may be straight or branched. The alkyl group may be straight or branched and the alkyl group may be bonded to any position of the phenyl group, as well as mixtures thereof.

[0047] Other molybdenum complexes are sulfur-containing molybdenum dithiolates, molybdenum dithioesters, or amide complexes terminated with molybdenum thioate.

[0048] In some embodiments, R and R' can be 1-4 rings or aromatic groups.

[0049] In some embodiments, the sulfur-containing molybdenum complex has the following general formula III:

[0050]

[0051] wherein R is as described above. In some embodiments, R is an alkyl group (straight chain, branched chain, or cyclic) with or without saturation or heteroatoms, or both; a thiolate, a sulfide, a dithiocarbamate, a dithiocarbonate, a dithioacid, an aromatic ring with or without substituents, an organic polysulfide, an inorganic polysulfide, and n is 2-10 or 2-6.

[0052] In some embodiments, R in the sulfur-containing molybdenum is a sulfur-containing phenol. In some embodiments, the sulfur-containing phenol is ethylhexylphenol; 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), bis(3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, and 2,2'-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

[0053] In some embodiments, R and R' are each an organic polysulfide or an inorganic polysulfide. The inorganic polysulfide has 2-10, 2-8, or 3-7 sulfur atoms. In some embodiments, the organic polysulfide has the general formula IV:

[0054] R 2 —Sx—R 3 Formula IV

[0055] where R 2 and R 3 Each is as described above for R and R'. In some embodiments, R 2 and R 3 Each is an alkyl group (aliphatic, acyclic, aromatic and heterocyclic) and R 2 and R 3 may be the same or different; and x is in the range of 2 to 8.

[0056] In some embodiments, the polysulfide is di-(2-ethylhexyl) polysulfide, dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, and dicyclohexyl polysulfide.

[0057] In other embodiments, R, R', R2 and R3 are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, cyclohexyl, phenyl, naphthyl, tolyl, xylyl, benzyl, phenethyl, ethylhexyl thiolate, thiocarbamate, thiocarbonate, thioacid and mixtures thereof.

[0058] In some embodiments, the inorganic polysulfide is from S2 to S8.

[0059] In some embodiments, the sulfur-containing Mo complex is shown below.

[0060]

[0061] The arcs represent alkyl chains (straight, branched, and cyclic) with or without saturation or heteroatoms, or both; dithiocarbamates, dithiocarbonates, dithioacids, aromatic rings with or without substituents, organic polysulfides, or inorganic polysulfides.

[0062] In some embodiments, R, R', R2, and R3 in the sulfur-containing molybdenum complex are thiolates, thiocarbamates, thiocarbonates, thioacids, dithiolates, dithiocarbamates, dithiocarbonates, dithioacids, polymers thereof, and mixtures thereof.

[0063] In some embodiments, R, R', R2 and R3 in the sulfur-containing molybdenum complex are diethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, dipentyldithiocarbamate, dihexyldithiocarbamate, dioctyldithiocarbamate, didecyldithiocarbamate, didodecyldithiocarbamate, di(butylphenyl)dithiocarbamate, di(nonylphenyl)dithiocarbamate, or di(2-ethylhexyl)dithiocarbamate, or a mixture thereof.

[0064] In some embodiments, the sulfur-containing molybdenum complex is phosphorus-free or has little or no phosphorus. Such complexes provide longer life for catalysts used in hydrocarbon processing processes.

[0065] Any method known to those skilled in the art can be used to prepare the sulfur-containing molybdenum complex. For example, the sulfur-containing molybdenum complex can be prepared as described in Tribology International, Vol. 27, No. 6, pp. 379-386 (1994); Tribology International, Vol. 53, pp. 150-158 (2012); and U.S. Pat. No. 3,356,702, which are incorporated herein by reference in their entirety.

[0066] For example, molybdenum compounds in various oxidation states, such as 2-6, can be used and can be represented by the following composition: molybdic acid, ammonium molybdate, molybdenum salts such as MoOCl4, MoO2Br2, Mo2O3Cl6, molybdenum trioxide, or similar acidic molybdenum compounds. Acidic molybdenum compounds include molybdic acid, ammonium molybdate, and molybdenum trioxide. Molybdates include molybdenum oxide or molybdenum sulfide. The molybdate is reacted with a sulfur source. For example, sulfur sources include sulfur, hydrogen sulfide, sulfur monochloride, sulfur dichloride, phosphorus pentasulfide, R2Sx, where R is a hydrocarbon group, preferably a C1-40 alkyl group, and x is at least 2, inorganic sulfides and polysulfides such as (NH4)2Sx, where x is at least 1, thioacetamide, thiourea, and mercaptans of the formula RSH, where R is as defined above. Similarly, conventional sulfur-containing antioxidants such as wax sulfides and polysulfides, olefins, carboxylic acids, esters, and ester-olefins, and alkylphenols and their metal salts can be used as sulfurizing agents.

[0067] The compositions and methods described herein are useful for inhibiting corrosion. In some embodiments, the composition comprises, consists essentially of, or consists of at least one of the sulfur-containing molybdenum complexes described for corrosion inhibition.

[0068] The corrosion inhibition activity of the sulfur-containing molybdenum complexes is particularly useful for liquid hydrocarbons and petrochemicals during their processing, where process temperatures are elevated to about 175° C. to 600° C. In some embodiments, the sulfur-containing molybdenum complexes are used at process temperatures of 175° C. to 550° C.; 175° C. to 205° C.; 200° C. to 300° C.; or 200° C. to 450° C.; or 250° C. to 350° C.

[0069] In some embodiments, the sulfur-containing molybdenum complex is used to inhibit corrosion of metal containment or equipment exposed to a fluid source containing a corrosive agent. In some embodiments, the sulfur-containing molybdenum complex is used with an acidic fluid source. In some embodiments, the acidity is at least partially due to the presence of a corrosive agent such as naphthenic acid or other similar organic acid or phenol such as cresylic acid. In some embodiments, the corrosive agent comprises naphthenic acid, sulfur (e.g., hydrogen sulfide, organic sulfide, mercaptan, or sulfur dioxide), carbon dioxide, oxygen, sodium chloride, calcium chloride, or a combination thereof. In some embodiments, the fluid source comprises water, gas, liquid hydrocarbons, or a combination thereof. In some embodiments, the fluid source is a non-aqueous liquid. In some embodiments, the fluid source is gas oil and light lubricating oil fractions. In some embodiments, the sulfur-containing molybdenum complex is used to inhibit corrosion of a fluid source comprising gas oil and light lubricating oil fractions containing a corrosive agent comprising naphthenic acid, sulfur (e.g., hydrogen sulfide, organic sulfide, mercaptan, or sulfur dioxide), carbon dioxide, oxygen, sodium chloride, calcium chloride, or a combination thereof, and at a temperature greater than 175°C.

[0070] In some embodiments, the method comprises introducing the corrosion inhibiting composition into a metal containment vessel or metal surface. In some embodiments, the metal surface (e.g., the surface of a metal pipe, tube, tank, etc.) is introduced with a composition comprising at least a sulfur-containing molybdenum complex. In some embodiments, the metal surface is any suitable metal or metal alloy. For example, the metal surface may include steel (including stainless steel, galvanized steel, hot-dip galvanized steel, electrogalvanized steel, annealed hot-dip galvanized steel, carbon steel (e.g., mild steel)), nickel, titanium, tantalum, aluminum, copper, gold, silver, platinum, zinc, nickel-titanium alloy (nitinol), nickel alloys, chromium, iron, iridium, tungsten, silicon, magnesium, tin, alloys of any of the foregoing metals, coatings containing any of the foregoing metals, and combinations thereof. In some embodiments, the metal surface is carbon (mild) steel or higher alloys.

[0071] In some embodiments, the metal containment vessel is a tank, pipe, or other equipment having metal surfaces that are in contact with, or potentially in contact with, a fluid source, wherein the fluid source includes one or more corrosive agents and is at a temperature between 175° C. and 600° C. In other embodiments, the sulfur-containing molybdenum complex is introduced into distillation columns, trays, piping (e.g., pump circuits), and related equipment. In some embodiments, the sulfur-containing molybdenum complex is used to inhibit the corrosive effects of naphthenic acid, sulfur, or both in distilled hydrocarbons without requiring the use of expensive corrosion-resistant alloys in the distillation columns, stripping columns, trays, pump circuit piping, and related equipment.

[0072] Although gas oils and light lubricating oil fractions often contain naphthenic acids, which cause corrosion problems, and the sulfur-containing molybdenum complexes are described in this context, the sulfur-containing molybdenum complexes are useful not only for inhibiting corrosion in the portion of the refinery that processes these petroleum intermediates, but are useful throughout the refinery where acidic hydrocarbons come into contact with metal-containing surfaces (e.g., iron-containing surfaces) and at high temperatures of 175°C to 600°C.

[0073] In some embodiments, the corrosion inhibiting composition includes a solvent suitable for formulating the sulfur-containing molybdenum complex. In some embodiments, the solvent is water, brine, seawater, an alcohol such as methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, or a higher alcohol such as benzyl alcohol); a ketone such as acetone or methyl ethyl ketone (2-butanone); acetonitrile; an ester such as ethyl acetate, propyl acetate, and butyl acetate; an ether such as diethyl ether or a higher ether, for example, methyl tert-butyl ether, glyme, diglyme, ethylene glycol monobutyl ether, ethylene diglycol ethyl ether, 1,4-dioxane, and related substances; an aromatic such as toluene, xylene, diethylbenzene, naphthalene, and related aromatic substances or refinery cuts (heavy aromatic naphtha, heavy aromatic distillates, and related substances); an aliphatic such as pentane, hexane, heptane, octane, or refined gasoline; or several "green" solvents such as 2-methyltetrahydrofuran, furfural alcohol, and cyclopentyl methyl ether.

[0074] In some embodiments, solvents suitable for preparing molybdenum-containing compositions are aliphatics, such as pentane, hexane, cyclohexane, methylcyclohexane, heptane, decane, dodecane, etc.; aromatics, such as toluene, xylene, heavy aromatic naphtha, diesel, fatty acid derivatives (acids, esters, amides), etc.

[0075] In some embodiments, the one or more solvents are 10 wt% to 99 wt% of the corrosion inhibiting composition; 1-25 wt%; 20-50 wt%; 30-75 wt%; 50-75%; 75-100 wt% of the corrosion inhibiting composition.

[0076] In some embodiments, the sulfur-containing molybdenum complex is provided in pure form (ie, without solvent).

[0077] In some embodiments, the sulfur-containing molybdenum complex is provided as a concentrate. In some embodiments, the method comprises introducing the molybdenum-containing concentrate directly into the metal containment vessel in an amount that results in 0.1 ppm to 10,000 ppm (by weight or by volume) of the sulfur-containing molybdenum complex in the fluid source. In other embodiments, the method further comprises diluting the sulfur-containing molybdenum complex concentrate prior to introduction. The dilution comprises, consists essentially of, or consists of combining the sulfur-containing molybdenum complex concentrate with a diluent, wherein the diluent comprises, consists essentially of, or consists of a hydrocarbon-based solvent, a hydrocarbon source, a hydrocarbon-soluble solvent, or a mixture of two or more thereof; and optionally comprises mixing the sulfur-containing molybdenum complex concentrate with the diluent prior to introducing the sulfur-containing molybdenum complex into the fluid source.

[0078] In some embodiments, the pH of the fluid source is less than 7. In some embodiments, the pH of the fluid source is between about 1 and about 6, between 5 and 6, between 4 and 5, between 3 and 4, between 2 and 3, between 1 and 2, or between 0 and 1.

[0079] In some embodiments, different doses of the corrosion inhibiting composition and / or the sulfur-containing molybdenum complex are introduced into the fluid source to inhibit corrosion of the metal containment vessel in contact with the fluid source. The most effective amount of corrosion inhibitor or inhibitor mixture to be used may vary, depending on the local operating conditions, the specific hydrocarbon being processed, the temperature and other characteristics of the acid corrosion system that may affect the amount of corrosion inhibitor or corrosion inhibitor mixture to be used. For a given situation, one of ordinary skill in the art can calculate the amount of sulfur-containing molybdenum complex or composition containing the sulfur-containing molybdenum complex without undue experimentation. Other factors considered important in such calculations include, for example, the amount of corrosive agent in the fluid source, the amount of naphthenic acid or acid, and similar parameters.

[0080] In some embodiments, the composition comprising the sulfur-containing molybdenum complex is applied to fluid sources containing varying acid levels. In some embodiments, the hydrocarbon contains naphthenic acid.

[0081] A method for determining the acid concentration in crude oil is to perform a potassium hydroxide (KOH) titration on the oil. The oil is titrated with the strong base KOH to an endpoint to ensure that all the acid in the sample has been neutralized. This titration is measured in milligrams of KOH per gram of sample and is referred to as the "Total Acid Number" (TAN) or neutralization number. The two terms are used interchangeably in this application.

[0082] The unit TAN is generally used because the acidity of an oil cannot be calculated based on moles of acid or any other commonly used analytical term for acid content. In some embodiments, naphthenic acid corrosion occurs when the crude oil being processed has a TAN greater than 0.2. In some embodiments, the sulfur-containing molybdenum complex is used with a fluid source (e.g., hydrocarbon) having a TAN of 0.2 to 20. In some embodiments, the fluid source has a TAN of 0.2 to 0.5; 0.5 to 5; 2 to 10; 7 to 15; 10 to 15; or 15 to 20.

[0083] In some embodiments, the sulfur-containing molybdenum complex or composition is applied to a fluid source containing various sulfur levels. In one embodiment, the fluid source has about 0.1% to about 25% sulfur; about 0.1% to about 10% sulfur; about 1% to about 10% sulfur; or about 6% to about 25% sulfur, weight / weight (w / w).

[0084] In some embodiments, the amount of sulfur-containing molybdenum complex or composition used is about 0.1 ppm to 10,000 ppm; 0.1 ppm to 3,000 ppm; about 100 ppm to 1000 ppm; about 500 ppm to 3,000 ppm; about 750 ppm to 3,000 ppm; about 2,000 ppm to 5,000 ppm; about 3,000 ppm to 5000 ppm; about 100 ppm to 3,000 ppm; 0ppm; about 1ppm to 1000ppm; about 1ppm to 3,000ppm; about 10ppm to 50ppm; about 50ppm to 100ppm, 100ppm to 800ppm, 150ppm to 550ppm; about 1ppm to 250ppm; about 1ppm to 50ppm; about 1ppm to 25ppm; about 1ppm to 5ppm; about 3ppm to 25ppm; 0.1ppm to 5ppm; or about 0.1ppm to 1ppm.

[0085] In some embodiments, the sulfur-containing molybdenum complex is introduced at an initial dosage rate of about 1 ppm to about 3,000 ppm and maintained at this level for a period of time ranging from 1 hour to 48 hours until the sulfur-containing molybdenum complex induces the accumulation of an anti-corrosion coating on the metal surface. In other embodiments, the sulfur-containing molybdenum complex is administered at a concentration of at least twice the initial dosage rate of 1 ppm to about 3,000 ppm for a period of time ranging from 1 hour to several hours prior to the introduction of the TAN-containing fluid. Once a protective surface is established, the dosage rate required to maintain protection can be reduced to at least 1-250 ppm without substantially sacrificing protection. In other embodiments, the sulfur-containing molybdenum complex is administered at a concentration of at least twice the initial dosage rate for a period of time ranging from one hour to several hours while the TAN-containing fluid is introduced.

[0086] Once a protective surface is established, the dosage rate required to maintain protection can be reduced by 1 ppm to 3000 ppm or at least 1 ppm to 1,000 ppm. In some embodiments, the dosage for continuous application of the sulfur-containing molybdenum complex to the fluid is 1 ppm to 1000 ppm; 1-500 ppm, 1-250 ppm, 100-100 ppm, or 500-1000 ppm without substantially sacrificing protection.

[0087] In some embodiments, the sulfur-containing molybdenum complex provides about 50-99%, 75-99%, or 75-50% corrosion inhibition for a metal containment vessel in contact with a fluid source. In some embodiments, the sulfur-containing molybdenum complex provides about 50-99% corrosion protection for a metal containment vessel in contact with a fluid source, as determined by 1018 carbon steel coupons in coupon testing described in Examples 1-2. In some embodiments, the method provides at least 70%, about 70-90%, 75-85%, or 80-90% corrosion protection to a 1018 carbon steel coupon test, wherein the test is characterized by a test temperature of about 250°C to 350°C; naphthenic acid in paraffin oil wherein the KOH is about 0.5-12 TAN; a test duration of 2-4 hours; and a corrosion inhibitor dosage of 25 ppm, 50 ppm, 75 ppm, 100 ppm, 175 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 500 ppm, or 1,000 ppm by total fluid volume.

[0088] In some embodiments, the methods provide at least 65%, about 65-80%, 70-90%, 75-85%, or 80-90% protection after two hours, at least 85% protection after 8 hours, and about 100% protection after 10 hours.

[0089] In some embodiments, the sulfur-containing molybdenum complexes or compositions containing them include other additives, such as one or more asphaltene inhibitors, paraffin inhibitors, dispersants, demulsifiers, defoamers, or any combination thereof. In some embodiments, the sulfur-containing molybdenum complexes further include one or more solvents or mixtures thereof.

[0090] In some embodiments, the sulfur-containing molybdenum complex is introduced into the fluid source by any means suitable for ensuring that the sulfur-containing molybdenum complex is dispersed throughout the fluid source being treated and introduced at multiple different locations throughout a given system. Depending on the application and requirements, the composition containing the sulfur-containing molybdenum complex can be injected as prepared or formulated in one or more additional solvents.

[0091] In one embodiment, a composition comprising a molybdenum-containing chemical is pumped into an oil / gas line using an integrated tubing bundle. In some embodiments, a capillary column injection system can be used to deliver the composition. U.S. Patent No. 7,311,144 provides a description of apparatus and methods related to capillary injection, the disclosure of which is incorporated herein in its entirety. In other embodiments, a composition comprising one or more sulfur-containing molybdenum complexes is injected using mechanical equipment such as a chemical injection pump, a pipe tee, an injection fitting, and the like.

[0092] Introducing can also be achieved by mixing, with mechanical mixing equipment or devices, fixed mixing configuration or equipment, magnetic mixing or other suitable methods, other equipment and means known to those skilled in the art, and their combination blending, so that the composition is fully contacted and / or dispersed into the fluid source. Contact can be carried out online and / or offline. The various components of the composition can be mixed before and / or during contact. If necessary or desired, then some of the composition or its components can be optionally removed or separated by mechanical, chemical or other methods known to those skilled in the art. It will be understood by those skilled in the art that the methods disclosed herein are not subject to any restrictions on the method of introduction, the time of introduction or the position.

[0093] A molybdenum complex is used to passivate the surface of process equipment to provide a method for treating the process equipment. The treated process equipment reduces corrosion on the metal surface. Examples of passivation are described in U.S. Patent Nos. 4,024,050, 3,522,093, 6,228,253, 9,845,437, ASTM A-967, and ASTM A-380, which are incorporated herein by reference in their entirety. In some embodiments, passivation is performed before the process equipment is used for treatment and / or after the process equipment has been cleaned, and is referred to herein as pre-passivation.

[0094] In some embodiments, the sulfur-containing molybdenum complex is introduced into the hydrocarbon feedstock prior to or during processing of the hydrocarbon feedstock and is referred to herein as passivation. In the pre-passivation or passivation process, in some embodiments, the molybdenum complex is introduced continuously or intermittently.

[0095] In some embodiments, the sulfur-containing molybdenum complex is used with water strippers and wastewater strippers, and with petrochemical processes such as styrene, butadiene, acrylonitrile, and ethylene processes. In some embodiments, ethylene acid gas scrubbers and butadiene solvent recovery systems are also end-use applications for the sulfur-containing molybdenum complex.

[0096] Sulfur-containing molybdenum complexes are not used in process equipment such as engines, hydraulic brakes, power steering systems, or transmissions, nor are they used as coolant additives in hydraulic fluids.

[0097] Sulfur-containing molybdenum complexes can also be used as corrosion inhibitors for other industrial systems. In some embodiments, the sulfur-containing molybdenum complexes are used as disclosed in U.S. Provisional Application No. 63 / 058,023, filed on July 29, 2020.

[0098] In some embodiments, the sulfur-containing molybdenum complexes are used in the metallurgical industry, mining systems, water recovery systems, water purification systems, food processing systems (meat, fruit, and vegetables), waste treatment systems, municipal sewage, and water treatment systems.

[0099] Examples

[0100] The following examples are intended to illustrate various aspects and embodiments of the present application and should not be considered limiting. It should be appreciated that various modifications and changes can be made to the experimental embodiments described herein without departing from the scope of the claims.

[0101] Example 1 - High Temperature Corrosion Inhibition (Prophetic)

[0102] The performance of the test complexes will be evaluated via weight loss analysis (corrosion rate) of the specimens using the autoclave corrosion test method.

[0103] Table 1 shows the experimental parameters that will be used for the high temperature corrosion test:

[0104] Table 1. Experimental parameters used for high temperature corrosion testing

[0105]

[0106] Sample pre-passivation step

[0107] 500 mL of the paraffin oil solution was placed in a 1 L glass reactor. The paraffin oil solution was heated to 250° C., 1,000 ppm of each of the tested corrosion inhibitors was injected therein, and the resulting paraffin oil solution was stirred at 250° C. for 1 hour.

[0108] The metal sample will first be weighed on an analytical balance (four decimal places). The metal sample will then be immersed in paraffin oil heated at 250°C with a continuous nitrogen purge. After 1 hour of passivation, the heating will be stopped. Once the oil has cooled (≤80°C), the sample will be removed from the oil, rinsed with toluene and isopropanol, and dried using a stream of nitrogen.

[0109] Autoclave corrosion testing

[0110] In 1L autoclave container, add 500mL paraffin oil solution (having 11.5TAN).Pre-passivation C1018 sample (as mentioned above) will be weighed on analytical balance (four decimal places), and is attached to the rotating shaft of autoclave container via a group of ceramic spacers that will be held together by screws. Subsequently, a group of bolts / screws will be used to seal and tighten the container. The atmosphere in the container will first use three rounds of 100psi N2 to fill / release N2 to purge. The reactor then uses N2 to be pressurized to 100psi, and then inserts into the heating element or sleeve. When the container is heated to 320 ℃, the system is set to rotate at 50rpm. Once the target temperature of 320 ℃ is reached, the rotation rate is increased to 440rpm, and the experiment runs for 4 hours.

[0111] Subsequently, the heating jacket will be turned off and the motor speed will be reduced to 50 rpm. The container will be allowed to cool for 30 minutes. When the container temperature drops below 150°C, the autoclave will be removed from the heating jacket and allowed to cool further in the fume hood. Once the container temperature drops below 70°C, the pressure in the container will be released, and the sample will then be removed, rinsed with toluene, and washed with a multi-purpose paper towel. The sample will then be rinsed with toluene, isopropanol, and dried using a stream of N2. The dried sample will be weighed using the same analytical balance that was originally used to weigh the pre-passivated C1018 sample, and the corrosion rate will be calculated using Equation 1. The container will then be cleaned with toluene, isopropanol, and dried in an oven.

[0112] The corrosion rate or weight loss is calculated using Equation 1:

[0113]

[0114] in

[0115] ΔW = weight loss in grams

[0116] A = in cm 2 is the unit area,

[0117] T = time in hours, and

[0118] D = in g / cm 3 Metal density in units of

[0119] The following sulfur-containing molybdenum complexes will be tested as described above for dose response curves: sulfur-containing thiols, Mo; sulfur-containing dialkyldithiocarbamates, Mo; sulfur-containing dialkyldithiocarbonates, Mo; sulfur-containing Mo dialkyldithioacids and sulfur-containing Mo polysulfides, compared to comparative compounds such as mono- and dialkyl phosphates or mixtures of organic or inorganic polysulfides; or thiolates over a dosage range of 100-800 ppm.

[0120] Example 2 (foreshadowing)

[0121] The performance of the sulfur-containing molybdenum test complex (as described in Example 1) will be compared with the performance of the sulfur-based product in the manner described in Example 1. The sulfur-based product to be tested will be compared with a comparative compound such as a branched alkyl-terminated polysulfide compound; a normal alkane-terminated polysulfide compound; a known industry standard inhibitor such as a phosphate ester. A blank is a sample without the test complex or comparative compound.

Claims

1. A method of inhibiting corrosion of a metal surface in contact with a hydrocarbon fluid source containing an acid corrosive agent, comprising: A phosphorus-free, sulfur-containing molybdenum complex having a general formula selected from Formula I or II is introduced into the hydrocarbon fluid source containing the acid etchant: wherein R of formula I each represents a group selected from an alcohol group, an alkyl group, an alkenyl group or an aryl group; and n is 4 to 10; wherein R and R' of formula II each represent a group selected from alcohol, alkyl, alkenyl or aryl; and each X is independently selected from oxygen or sulfur, but wherein at least one X in formula II is sulfur.

2. The method of claim 1, wherein the hydrocarbon fluid source is contacted with a distillation column, a stripping column, a tray, or a pipeline.

3. The method of claim 1, wherein the hydrocarbon fluid source comprises a liquid hydrocarbon fraction.

4. The process according to claim 3, wherein the liquid hydrocarbon fraction is a distillate.

5. The method of any one of claims 1 to 4, wherein the acid etchant comprises an etchant selected from the group consisting of naphthenic acid, sulfur, and combinations thereof.

6. The method of claim 1, wherein the hydrocarbon fluid source comprises a total acid number of 0.2 to 20.

7. The method of claim 1, wherein the hydrocarbon fluid source has a temperature of 175°C to 600°C.

8. The method of claim 1, wherein the sulfur-containing molybdenum complex is added to the hydrocarbon fluid source at a dosage rate of 1 ppm to 3,000 ppm.

9. The method of claim 1, wherein the sulfur-containing molybdenum complex further comprises one or more additives selected from the group consisting of asphaltene inhibitors, paraffin inhibitors, dispersants, demulsifiers, and any combination thereof.

10. A composition comprising a phosphorus-free, sulfur-containing molybdenum complex to inhibit corrosion of a metal surface in contact with a hydrocarbon fluid source containing an acid corrosive agent, wherein the phosphorus-free, sulfur-containing molybdenum complex has a general formula selected from Formula I or II: wherein R of formula I each represents a group selected from an alcohol group, an alkyl group, an alkenyl group or an aryl group; and n is 4 to 10; wherein R and R' of Formula II each represent a group selected from alcohol, alkyl, alkenyl or aryl; and each X is independently selected from oxygen or sulfur, but wherein at least one X in Formula II is sulfur.

11. The composition of claim 10, wherein the composition further comprises one or more additives selected from the group consisting of asphaltene inhibitors, paraffin inhibitors, dispersants, demulsifiers, and any combination thereof.

12. The composition of claim 10, wherein the hydrocarbon fluid source is contacted with a distillation column, a stripping column, a tray, or a pipeline.

13. The composition of claim 10, wherein the hydrocarbon fluid source comprises a liquid hydrocarbon fraction.

14. The composition of claim 13, wherein the liquid hydrocarbon fraction is a distillate.

15. The composition of any one of claims 10 to 14, wherein the acid etchant comprises an etchant selected from the group consisting of naphthenic acid, sulfur, and combinations thereof.

16. The composition of claim 10, wherein the hydrocarbon fluid source comprises a total acid number of 0.2 to 20.

17. The composition of claim 10, wherein the hydrocarbon fluid source has a temperature of 175°C to 600°C.

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