Membrane-Assisted Flow Reactor for the Extraction of Sulfur Compounds in Petroleum Crude and its Fractions

Removal of sulfur compounds from crude oil samples was evaluated using a membrane extraction (ME) flow reactor. Ionic liquid, 1-Ethyl-3-methylimidazolium trifluoromethane sulfonate ([EMIM]⁺ [CF₃SO₃]⁻), immobilized on the pores of propylene sheet membranes, was used as a supported liquid membrane (SLM). A polar organic solvent was introduced between two SLM as an acceptor phase. The crude oil samples were continuously flowed through the supported liquid membrane to remove the polar sulfur compounds into the acceptor phase via the ionic liquid. Experimental conditions that are influencing the sulfur removal were optimized. Sulfur-free diesel samples spiked with known concentrations of 19 target analytes was utilized for method optimization. The optimized ME method was applied to Arabian crude and diesel samples. Gas chromatography-sulfur chemiluminescence detection and high-resolution mass spectrometry were used for the quantitation of sulfur compounds. The ME method extracted 58% of total sulfur content from Arabian Light crude oil, 48% from Arabian Medium crude oil, 44% from diesel, and 43% from Arabian Heavy crude oil. The use of disposable porous membranes in the ME process with a small volume of extraction solvent offers many advantages such as low cost, high preconcentration factor, and higher extraction efficiency.