A new, more efficient platform for removing sulfur is needed by the industry, as validated by the strong interest in our approach. Oxidative desulfurization with hydrogen peroxide (or perhaps other liquid) and subsequent solvent extraction is a two-stage deep desulfurization technology to reduce the amount of organosulfur compounds in fuel oil.
At the first stage of ultrasonically assisted oxidative desulfurization, hydrogen peroxide is used to selectively oxidize the sulfur-containing molecules that are present in fuel oils. This process, carried out under mild conditions, creates sulfoxides or sulfones with greater solubility in polar solvents. Without expertise in ultrasonication, the insolubility of the polar aqueous phase and the nonpolar organic phase has a very low reaction rate and both phases react with each other only at the interphase.
Ultrasonic cavitation produces intense local heating (~5000K), high pressures (~1000atm) and enormous heating and cooling rates (>100 K/sec). Amphiphilic emulsion catalysts or phase-transfer catalysts (PTC), such as quaternary ammonium salts, have been shown to incorporate with the oxidant and transport
it from the interface phase to the reaction phase, thereby enhancing the reaction rate.
After oxidation and separation from the aqueous phase (H2O2), the sulfones can be extracted using a polar solvent, such as acetonitrile. The sulfones will transfer at the phase boundary between both phases to the solvent phase for their higher polarity. Much like at the first stage, ultrasonic reactors boost the liquid-liquid
extraction by making a high surface area, turbulent emulsion of the solvent phase in the oil phase for better extraction and reduced solvent usage.