Patent ID: 8440072

Claim:
A method of removing metals from hydrocarbon feedstock using esters of carboxylic acids or combinations thereof, comprising the steps of: a) mixing a hydrocarbon stream containing metals and salts thereof, wherein the metal includes calcium and its salt is calcium naphthenate, with an effective metal removing amount of an aqueous extraction solution of non-precipitating and non-fouling additive comprising a chemical compound selected from a group consisting of: i) methyl or ethyl or propyl or isopropyl mono-esters of any one of the carboxylic acids selected from the group consisting of maleic acid, maleic anhydride, and fumaric acid; ii) methyl or ethyl or propyl or isopropyl di-esters of any one of the carboxylic acids selected from the group consisting of maleic acid, maleic anhydride, and fumaric acid; iii) an appropriate combination of said esters; and iv) an appropriate combination of any of said esters with any of said carboxylic acids; b) forming an aqueous phase and a hydrocarboneous phase, wherein said aqueous phase includes an ionic water soluble metal acid complex of the calcium salt of said additive; c) separating or permitting to separate by themselves said two phases in a crude desalter, or by using a conventional separation process; d) removing the separated aqueous phase of step c), containing said metal acid complex; e) processing the separated hydrocarboneous phase of step c) by a downstream hydrocarbon processing technique; wherein the contact time between said aqueous extraction solution and said hydrocarbon stream during the mixing action of step a) is in the range from two seconds to six hours; wherein the temperature in said desalter is in the range from 93° C. to 163° C.; and wherein, the weight percentage of the dosage of said chemical compound ranges from 0.001 to 5 of weight of said desalter wash water.