High temperature naphthenic acid corrosion control in hydrocarbon processing with dispersant-based corrosion inhibitor

Abstract

A corrosion inhibiting composition for use in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between 350°F and 790°F comprising adding to the crude oil a corrosion inhibiting amount of a composition comprising (a) an organophosphorus chemistry; and (b) a dispersant chemistry.

Description

HIGH TEMPERATURE NAPHTHENIC ACID CORROSION CONTROL IN HYDROCARBON PROCESSING WITH DISPERSANT-BASED CORROSION INHIBITORCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to India Provisional Patent Application No. 202311035329. filed on May 20, 2023. which is incorporated by reference herein in its entiretyFIELD

[0002] The disclosed technology relates generally to compositions and methods for inhibiting corrosion in refining operations. More specifically, the disclosed technology relates to compositions and methods for inhibition of corrosion caused by naphthenic acids which are present in crude oil.BACKGROUND

[0003] Corrosion problems in petroleum refining operations associated with naphthenic acid constituents in crude oils have been recognized for many years. Such corrosion is particularly severe in atmospheric and vacuum distillation units at temperatures between 350°F and 790°F. Other factors that contribute to the corrosivity of crudes containing naphthenic acids include the amount of naphthenic acid present, the concentration of sulfur compounds, the velocity and turbulence of the flow stream in the units, and the location in the unit (e.g., liquid vapor interface).

[0004] In the distillation refining of crude oils, the crude oil is passed successively through a furnace, and one or more fractionators such as an atmospheric tower, as well as a vacuum tower. In most operations, naphthenic acid corrosion is not a problem at temperatures below about 400°F. Traditional nitrogen-based filming corrosion inhibitors are not effective at these high temperatures and the other approaches for preventing naphthenic acid / sulfur corrosion, such as neutralization, present operational problems or are not effective.

[0005] It should be observed that the term "naphthenic acid" includes mono- and di-basic carboxylic acids and generally constitutes about 50 percent by weight of the total acidic components in crude oil. Naphthenic acids may be represented by the following formula:

[0007] where R is an alkyl or cycloalkyl and n ranges generally from 2 to 10.

[0008] Many variations of this structure and molecular weight are possible. Some practitioners include alkyl organic acids within the class of naphthenic acids.

[0009] Naphthenic acids are corrosive between the range of about 210°C (400°F) to 420°C (790°F). At the higher temperatures the naphthenic acids are either in the vapor phase or decompose / decarboxylate, and at the lower temperatures the corrosion rate is not serious. The corrosivity7of naphthenic acids appears to be exceptionally serious in the presence of significant levels of sulfurous compounds, such as hydrogen sulfide.

[0010] Efforts to minimize or prevent the naphthenic acid / sulfidic corrosion have included the following approaches:

[0011] (a) blending of higher naphthenic acid content oil with oil low in naphthenic acids;

[0012] (b) neutralization and removal of naphthenic acids from the oil; and

[0013] (c) use of corrosion inhibitors.

[0014] Because these approaches have not been entirely satisfactory, the accepted approach in the industry is to construct the distillation unit, or the portions exposed to naphthenic acid corrosion, with resistant metals such as high-quality7stainless steel or alloys containing higher amounts of chromium and molybdenum. However, in units not so constructed there is a need to provide inhibition treatment against this type of corrosion. The traditional corrosion inhibitors for naphthenic acid environments include nitrogen based filming corrosion inhibitors, which are relatively ineffective in the high temperature environment of naphthenic acid oils, and phosphate / phosphonate based chemistries, which can act as a poison for catalysts used in downstream upgrading units and further pose downstream fouling problems.SUMMARY

[0015] The disclosed technology provides for compositions and methods for inhibiting corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil.

[0016] Various aspects of the disclosure relate to a corrosion inhibiting composition for use in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between 350°F and 790°F. the composition comprising a corrosion inhibiting amount of (a) an organophosphorus chemistry'; and (b) a dispersant chemistry'.

[0017] Various aspects of the disclosure additionally relate to a method of inhibiting corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between 350°F and 790°F comprising adding to the crude oil a corrosion inhibiting amount of a composition comprising (a) an organophosphorus chemistry; and (b) a dispersant chemistry.

[0018] In various aspects, the dispersant chemistry may be selected from alkenyl succinic acids; alkenyl succinic acid reaction products with polyamines; alkenyl succinic acid reaction products with polyhydric alcohols; alkenyl thiophosphonic acid reaction products with polyhydric alcohols; alkenyl phosphonates or esters; metal salts of alkylphenol sulfide; metal salts of alkyl or aryl sulfonate; metal salts of alkyl salicylate; reaction products of fatty acid and polyamine; reaction products of fatty acid, formaldehyde and polyamine; reaction products of fatty' acid and hydroxylated amine; reaction products of alkylphenol, formaldehyde and polyamine; reaction products of maleic anhydride, alkenyl hydrocarbons, polyamines, and aryl anhydride; reaction products of aryl anhydride, alkenyl hydrocarbons, and polyamines; glycolipids; derivatives thereof; or mixtures thereof.DETAILED DESCRIPTION

[0019] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly van’ without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, is not limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be combined and / or interchanged, and such ranges are identified and include all the sub-ranges stated herein unless context or language indicates otherwise. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions and the like, used in the specification and the claims, are to be understood as modified in all instances by the term “about”.

[0020] “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present.

[0021] As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having”, or any other variation thereof, are intended to cover a nonexclusive inclusion. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0022] The singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0023] The disclosed technology provides for compositions and methods for inhibiting corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil comprising a mixture of an organophosphorus chemistry and a dispersant chemistry.

[0024] The compositions and methods disclosed herein have unexpectedly been found to work synergistically to provide enhanced corrosion protection in comparison to their individual components. Without being bound by a particular theory, it is postulated that the protective film formed by the organophosphorus chemistry, such as a phosphateester component, is made more effective and / or stronger by the addition of the dispersant chemistry of the disclosure.

[0025] As used herein, the term “a corrosion inhibiting amount'’ refers to any amount of the disclosed composition that is effective in inhibiting and / or preventing corrosion on the internal metallic surfaces of the equipment used in the processing of crude oil.

[0026] In various aspects of the disclosed technology, a corrosion inhibiting composition for use in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil is disclosed. In various aspects, the corrosion inhibiting composition comprises a mixture of (a) an organophosphorus chemistry', and (b) a dispersant chemistry'.

[0027] In various aspects, suitable organophosphorus chemistries may include any phosphate or phosphonate or phosphite ester compound or their combinations that is effective in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil. In some aspects, the organophosphorus chemistries may be alkoxylated (ethoxylated, propoxylated or butoxylated) in one or more combinations. In some aspects, suitable phosphate esters may include dialkyl phosphates or trialkyl phosphates. In some aspects, suitable dialkyl phosphates may include 2-ethylhexyl phosphate. In some aspects, suitable trialkyl phosphates may include trialkyl phosphates containing an alky l moiety7of C1-C12, such as trimethylphosphate, triethylphosphate, tripropylphosphate, tributylphosphate and tripentylphosphate.

[0028] In various aspects, the organophosphorus chemistry may be present in the composition in an amount of from about 1% to about 95% by weight of the composition, or about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% by weight of the composition, or from about 5% to about 90% by weight of the composition, or any percentage between any of these values.

[0029] In vanous aspects suitable dispersant chemistries may include any dispersant compound that is effective in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil. In some aspects, suitable dispersant compounds may include alkenyl succinic acids; alkenyl succinic acid reaction products with polyamines; alkenyl succinic acid reaction products with polyhydric alcohols; alkenyl thiophosphonic acid reaction products with polyhydric alcohols; alkenylphosphonates or esters; metal salts of alkylphenol sulfide; metal salts of alkyl or aryl sulfonate; metal salts of alkyl salicylate; reaction products of fatty acid and polyamine; reaction products of fatty' acid, formaldehyde and polyamine; reaction products of fattyacid and hydroxylated amine; reaction products of alkylphenol, formaldehyde and polyamine; reaction products of maleic anhydride, alkenyl hydrocarbons, polyamines, and aryl anhydride; reaction products of aryl anhydride, alkenyl hydrocarbons, and polyamines; glycolipids; derivatives thereof; or mixtures thereof. In some aspects, suitable alkenyl succinic acid derivatives may include polyalkenyl succinimide, such as polyisobutylene succinimide.

[0030] In various aspects, the dispersant chemistry- may be present in an amount of from about 1% to about 50% by weight of the composition, or from about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% 45%, or 50% by weight of the composition, or from about 5% to about 30% by weight of the composition or about 5% to 20% by weight of the composition, or any percentage between any of these values.

[0031] In various aspects, the corrosion-inhibiting composition may be used to inhibit corrosion on the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between about 350°F to about 790°F.

[0032] In various aspects, the corrosion-inhibiting compositions of the disclosed technology may be used in a method of inhibiting corrosion on the internal metallic surfaces of the equipment used in the processing of crude oil. In various aspects, the method may include adding to the crude oil a corrosion inhibiting amount of a composition comprising a mixture of (a) an organophosphorus chemistry, and (b) a dispersant chemistry.

[0033] In various aspects, the method may include adding to the crude oil a corrosion inhibiting amount of any organophosphorus chemistry that may include any phosphate or phosphonate or phosphite ester or their combinations that is effective in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil. In some aspects, suitable organophosphorus chemistries may be alkoxylated (ethoxylated, propoxylated or butoxylated in one or more combinations. In some aspects, suitable phosphate esters may include dialkyl phosphates or trialkyl phosphates. In some aspects, suitable dialkyl phosphates may include 2-ethylhexyl phosphate. In some aspects, suitable trialkyl phosphates may include trialkyl phosphatescontaining an alkyl moiety of C1-C12, such as trimethylphosphate, triethylphosphate, tripropylphosphate, tribul lphosphate and tri pentyl phosphate.

[0034] In various aspects, the organophosphorus chemistry' may be added in an amount of from about 1% to about 95% by weight of the corrosion-inhibiting composition, or about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% by weight of the composition, or from about 5% to about 90% by weight of the composition, or any percentage between any of these values.

[0035] In various aspects, the method may include adding to the crude oil a corrosion inhibiting amount of any suitable dispersant chemistry that is effective in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil. In some aspects, suitable dispersant chemistries may include alkenyl succinic acids; alkenyl succinic acid reaction products with polyamines; alkenyl succinic acid reaction products with polyhydric alcohols; alkenyl thiophosphonic acid reaction products with polyhydric alcohols; alkenyl phosphonates or esters; metal salts of alkylphenol sulfide; metal salts of alkyl or aryl sulfonate; metal salts of alkyl salicylate; reaction products of fatty acid and polyamine; reaction products of fatty acid, formaldehyde and polyamine; reaction products of fatty acid and hydroxylated amine; reaction products of alkylphenol, formaldehyde and polyamine; reaction products of maleic anhydride, alkenyl hydrocarbons, polyamines, and aryl anhydride; reaction products of aryl anhydride, alkenyl hydrocarbons, and polyamines; glycolipids; derivatives thereof; or mixtures thereof. In some aspects, suitable alkenyl succinic acid derivatives may include polyalkenyl succinimide, such as polyisobutylene succinimide.

[0036] In various aspects, the dispersant chemistry may be added in an amount of from about 1% to about 50% by weight of the corrosion-inhibiting composition, or from about 1%, 5%, 10%. 15%, 20%, 25%, 30%, 35%, 40% 45%, or 50% by weight of the composition, or from about 5% to about 30% by weight of the composition or about 20% by weight of the composition, or any percentage between any of these values.

[0037] In various aspects, the method may include adding the corrosion-inhibiting composition of the disclosure to the crude oil at temperatures between about 350°F to about 790°F.

[0038] In various aspects of the disclosed method, the corrosion is caused by naphthenic acid present in the crude oil.

[0039] In various aspects of the disclosed method, suitable inner metallic surfaces that may be treated with the corrosion inhibiting compositions of the disclosure may include carbon steel, 5Cr (steel with 5% Cr), 9 Cr (steel with 9% Cr), 12Cr (steel with 12% Cr), SS410, SS316, or SS317.EXAMPLES

[0040] The present technology will be further described in the following examples, which should be viewed as being illustrative and should not be construed to narrow the scope of the disclosed technology or limit the scope to any particular embodiments.

[0041] Example 1

[0042] In order to understand field corrosion behaviour and to evaluate the performance of the inhibitors of the disclosure, an ASTM G184 test protocol was used for evaluation, as this test standard resembles pipeline corrosion in the refinery. A Rotating Cage Autoclave (RCA) apparatus was developed based on the ASTM G184 test standard. RCA is considered Top Ranked Methodology for Inhibitor Evaluation and Qualification for Pipeline Applications (evaluated by Sankara Papavinasam, R.Winston Revie, and Michael Attard). Based on the pipeline design and operating conditions, laboratory testing protocol was set to evaluate the similar field conditions. In order to study the behavior or effectiveness of corrosion inhibitors at high pressures and temperatures, autoclaves, or high-pressure reactors, were used. The autoclave vessels were equipped with external heaters, temperature controllers. Hastelloy vessels, baffles, magnetically coupled Hastelloy spindles and sparge gas tubes.

[0043] In principle, the rotating cage test was a mass loss test. Specimens of carbon steel (C1018) polished with 240 Grit sand paper were used for each experimental run. Before each test, the specimens were cleaned ultrasonically with toluene & isopropyl alcohol (IP A) and then in two successive batches of acetone. Each specimen was then measured and weighed to the nearest 0.1 mg. these coupons were mounted on to the rotating spindle (cage assembly), then assembled on to the body consisting of corrosive solution. The solution could be either synthetically prepared or actual field solution. Before starting, the study solution was purged with nitrogen fluid and parameters were set in the control panel. The study was carried out as per the required test conditions mentioned in the below Table 1.

[0044] Table 1

[0045] After each test, the specimens were rinsed with compatible solvents, and then weighed to the nearest 0. 1 mg to determine the weight after the test and before acid cleaning. Then they were cleaned in inhibited Clarke’s solution, rinsed in saturated NaHCOs, and then cleaned using distilled water. The specimens were then rinsed in isopropanol, and weighed to the nearest 0.1 mg. Corrosion rates were calculated as per the below formula.

[0046] Corrosion Rate = (534*Wl) / (p*Area*Time)

[0047] W1 = Weight Loss in mg

[0048] p = Density in gm / cm3

[0049] Area in inch square

[0050] Time in hours

[0051] Comparative benchmark corrosion inhibitor products were prepared by mixing an organophosphorus chemistry at 1.7% or 3.5% phosphorous (P) with a dispersant chemistry including an overbased salt of a reaction product of alkylphenol sulfide and phosphorosulfide in various concentrations (Benchmarks A-C). These benchmark corrosion inhibitor products were evaluated against embodiments of the corrosion inhibiting compositions of the disclosure (Dispersant Compositions A and B). which included 1.7% P from the organophosphorus chemistry in combination with various concentrations of a polyalkenyl succinimide dispersant.

[0052] As shown in Table 2 below, the inclusion of the polyalkenyl succinimide dispersant of the disclosure, in combination with the lowest amount of P tested, unexpectedly performed better than Benchmark C, which contained the higher amount of 3.5%P.

[0053] Table 2

[0054] While embodiments of the disclosed technology have been described, it should be understood that the present disclosure is not so limited and modifications may be made without departing from the disclosed technology'. The scope of the disclosed technology is defined by the appended claims, and all devices, processes, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.

Claims

CLAIMS1. A corrosion inhibiting composition for use in inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between 350°F and 790°F, the composition comprising a corrosion inhibiting amount of (a) an organophosphorus chemistry; and (b) a dispersant chemistry.

2. The composition of claim 1, wherein the dispersant chemistry is selected from alkenyl succinic acids; alkenyl succinic acid reaction products with polyamines; alkenyl succinic acid reaction products with polyhydric alcohols; alkenyl thiophosphonic acid reaction products with polyhydric alcohols; alkenyl phosphonates or esters; metal salts of alkylphenol sulfide; metal salts of alkyl or aryl sulfonate; metal salts of alkyl salicylate; reaction products of fatty acid and polyamine; reaction products of fatty acid, formaldehyde and polyamine; reaction products of fatty acid and hydroxylated amine; reaction products of alkydphenol, formaldehyde and polyamine; reaction products of maleic anhydride, alkenyl hydrocarbons, polyamines, and aryl anhydride; reaction products of aryl anhydride, alkenyl hydrocarbons, and polyamines; glycolipids; derivatives thereof; or mixtures thereof.

3. The composition of claim 1 or 2, wherein the organophosphorus chemistry is selected from a trialkyl phosphate containing an alkyl moiety of C1-C12, or a dialkyl phosphate, or combinations thereof.

4. The composition of claim 3, wherein the organophosphorus chemistry is selected from tribut I phosphate or 2-ethylhexyl phosphate, or combinations thereof.

5. The composition of any one of claims 1-4, wherein the dispersant chemistry is an alkenyl succinic acid derivative.

6. The composition of claim 5, wherein the alkenyl succinic acid derivative is polyisobutylene succinic acid reaction products with polyamines.

7. The composition of any one of claims 1-6, wherein the dispersant chemistry is present in an amount of from about 1% to about 50% by weight of the composition.

8. The composition of claim 7, wherein the dispersant chemistry is present in an amount of from about 5% to about 30% by weight of the composition.

9. The composition of claim 8, wherein the dispersant chemistry is present in an amount of about 20% by weight of the composition.

10. The composition of any one of claims 1-9, wherein the organophosphorus chemistry' is present in an amount of from about 1% to about 95% by weight of the composition.

11. The composition of claim 10, wherein the organophosphorus chemistry is present in an amount of from about 5% to about 90% by weight of the composition.

12. A method of inhibiting the corrosion of the internal metallic surfaces of the equipment used in the processing of crude oil at temperatures between 350°F and 790°F comprising adding to the crude oil a corrosion inhibiting amount of a composition comprising (a) an organophosphorus chemistry'; and (b) a dispersant chemistry'.

13. The method of claim 12, wherein the dispersant chemistry is selected from alkenyl succinic acids; alkenyl succinic acid reaction products with polyamines; alkenyl succinic acid reaction products with polyhydric alcohols; alkenyl thiophosphonic acid reaction products with polyhydric alcohols; alkenyl phosphonates or esters; metal salts of alkylphenol sulfide; metal salts of alkyl or aryl sulfonate; metal salts of alkyl salicylate; reaction products of fatty acid and polyamine; reaction products of fatty acid, formaldehyde and polyamine; reaction products of fatty' acid and hydroxylated amine; reaction products of alkylphenol, formaldehyde and polyamine; reaction products of maleic anhydride, alkenyl hydrocarbons, poly amines, and aryl anhydride; reaction products of aryl anhydride, alkenyl hydrocarbons, and polyamines; glycolipids; derivatives thereof; or mixtures thereof.

14. The method of claim 12 or 13, wherein the organophosphorus chemistry is selected from a trialky l phosphate containing an alky l moiety' of C1-C12, or a dialky l phosphate, or combinations thereof.

15. The method of claim 14, wherein the organophosphorus chemistry is selected from tributylphosphate or 2-ethylhexyl phosphate, or combinations thereof.

16. The method of any one of claims 12-15. wherein the dispersant chemistry is an alkenyl succinic acid derivative.

17. The method of claim 16, wherein the alkenyl succinic acid derivative is polyisobutylene succinic acid reaction products with polyamines.

18. The method of any one of claims 12-17, wherein the dispersant chemistry is present in an amount of from about 1% to about 50% by weight of the composition.

19. The method of claim 18. wherein the dispersant chemistry is present in an amount of from about 5% to about 30% by weight of the composition.

20. The method of claim 19, wherein the dispersant chemistry' is present in an amount of about 20% by weight of the composition.

21. The method of any one of claims 12-20, wherein the organophosphorus chemistry' is present in an amount of from about 1% to about 95% by weight of the composition.

22. The method of claim 21. wherein the organophosphorus chemistry is present in an amount of from about 5% to about 90% by weight of the composition.

23. The method of any one of claims 12-22, wherein the corrosion is caused by naphthenic acids present in the crude oil.

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