Process for removing hydrogen sulfide in crude oil

Abstract

A method for reducing the amount of hydrogen sulfide present in crude oil includes adding a hydrogen sulfide scavenger composition to the crude oil to capture the hydrogen sulfide, migrating the captured sulfides to an aqueous phase and removing the aqueous phase from the crude oil. The hydrogen sulfide scavenger composition includes glyoxal and a quaternary ammonium salt.

1 . A method for reducing the amount of hydrogen sulfide present in crude oil comprising adding a hydrogen sulfide scavenger composition to the crude oil to capture the hydrogen sulfide, migrating the captured sulfides to an aqueous phase and removing the aqueous phase from the crude oil, wherein the hydrogen sulfide scavenger composition comprises glyoxal and a quaternary ammonium salt. 
     
     
         2 . The method of  claim 1  wherein the scavenger composition is added to the crude oil in an amount of from about 1 ppm by weight to about 3000 ppm by weight, based on the weight of the crude oil. 
     
     
         3 . The method of  claim 1  wherein the scavenger composition is added to the crude oil in an amount of from about 10 ppm by weight to about 2000 ppm by weight, based on the weight of the crude oil. 
     
     
         4 . The method of  claim 1  wherein the catalyst has formula I:
   R 1 R 2 R 3 R 4 N + X −   I
 
 
       wherein R 1 , R 2 , R 3  and R 4  are each independently an alkyl group having from 1 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or an arylalkyl group having from 7 to 30 carbon atoms; and X is a halide, sulfate, nitrate or carboxylate. 
     
     
         5 . The method of  claim 4  wherein the alkyl group is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, decyl and dodecyl. 
     
     
         6 . The method of  claim 4  wherein the aryl group is phenyl. 
     
     
         7 . The method of  claim 4  wherein the arylalkyl group is benzyl. 
     
     
         8 . The method of  claim 4  wherein the halide is selected from the group consisting of chloride, bromide and iodide. 
     
     
         9 . The method of  claim 1  wherein the catalyst is alkyl benzyl ammonium chloride or benzyl cocoalkyl (C 12 -C 18 ) dimethylammonium chloride. 
     
     
         10 . The method of  claim 1  wherein the catalyst is selected from the group consisting of dicocoalkyl (C 12 -C 18 ) dimethylammonium chloride, benzyl cocoalkyl (C 12 -C 18 ) dimethylammonium chloride, ditallowdimethylammonium chloride, di(hydrogenated tallow alkyl) dimethyl quaternary ammonium methyl chloride, methyl bis(2-hydroxyethyl cocoalkyl (C 12 -C 18 ) quaternary ammonium chloride, dimethyl(2-ethyl) tallow ammonium methyl sulfate, n-dodecylbenzyldimethylammonium chloride, n-octadecylbenzyldimethyl ammonium chloride, n-dodecyltrimethylammonium sulfate, soya alkyltrimethylammonium chloride and hydrogenated tallow alkyl (2-ethylhyexyl) dimethyl quaternary ammonium methylsulfate. 
     
     
         11 . The method of  claim 1  wherein the quaternary ammonium salt is present from about 0.01 percent by weight to about 15 percent by weight based on the weight of the glyoxal. 
     
     
         12 . The method of  claim 11  wherein the quaternary ammonium salt is present from about 1 percent by weight to about 10 percent by weight, based on the weight of the glyoxal. 
     
     
         13 . The method of  claim 1  wherein the crude oil is treated in a desalter. 
     
     
         14 . The method of  claim 13  wherein a water wash is added to the crude oil. 
     
     
         15 . The method of  claim 14 , wherein the water wash is added in an amount of from about 1 percent by volume to about 50 percent by volume based on the volume of the emulsion. 
     
     
         16 . The method of  claim 14  wherein the water wash is added in an amount of from about 1 percent by volume to about 25 percent by volume of the emulsion. 
     
     
         17 . The method  claim 14  wherein the water wash and crude oil are emulsified by heating and mixing the crude oil and water wash. 
     
     
         18 . The method of  claim 14  wherein the crude oil and water wash are heated to a temperature in a range of from about 90° C. to about 150° C. 
     
     
         19 . The method of  claim 14  wherein the wash water is removed by draining.