Systems and methods for screening solvents for dissolving tank bottom sludge

A method of processing petroleum hydrocarbons, said method comprising:

• a) dissolving petroleum hydrocarbons in a selected solvent to form a first solution;
• b) measuring absorbance of the first solution;
• c) adding an ionic liquid to the first solution and blending to form a second solution;
• d) measuring absorbance of the second solution;
• e) determining an increase in absorbance of the second solution over the first solution to be at least about 70%;
• f) repeating steps a) to e) for a plurality of solvents and ionic liquids;
• g) selecting at least one solvent and one ionic liquid based on the determination in step e);
• and
• h) processing the petroleum hydrocarbons using the selected solvent and the ionic liquid in combination;
• wherein the ionic liquid is chosen from:
• 1,3-dimethylimidazolium 1,1,1-trifluoro-N-[(trifluoromethyl) sulfonyl] methane-sulfonamide;
• 1-butyl-1-methylpyrrolidinium 1,1,1-trifluoro-N-[(trifluoromethyl)-sulfonyl] methane-sulfonamide;
• diethylammonium phosphate;
• diethylammonium sulfate;
• triethylammonium phosphate;
• triethylammonium sulfate;
• tripropylammoniumsulfate;
• tributylammoniumsulfate;
• 1-butyl-3-methylimidazolium 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl] methanesulfonamide;
• 1-butyl-3-methyl imidazolium chloride;
• 1-butyl-3-methylimidazolium hexafluorophosphate;
• 1-ethyl-3-methylimidazolium ethyl sulfate;
• 1-hexyl-3-methylimidazolium hexafluorophosphate;
• 1-decyl-3-methylimidazolium bis(trifluoromethyl sulfonyl) imide;
• 1-octyl-3-methylimidazolium chloride;
• 1-hexyl-3-methylimidazolium hydrogen sulfate;
• triethylammoniumtetrafluoroborate;
• triethylammonium acetate;
• and mixtures thereof.