A plausible reaction pathway of asphaltene under ultrasound

Abstract In an earlier report [Energy Fuels, 7 (1993) 111], the potential benefits of a refining process for heavy oil through the chemical assisted ultrasound method at room temperature and ambient pressure were presented. Specifically, with the effects of cavitation and added surfactant, within 15 min from the original bitumen, 35% of asphaltene was converted into gas oil and resin fractions. The present investigation is a continuous effort to provide more information about this conversion process, particularly studying the role of water during the ultrasound conversion process. The question to be answered is: “To what degree is the participation of hydrogen, which was used for the conversion process, a result from the water medium?” In order to trace the fate of hydrogen in a water medium, deuterium oxide was chosen to compare with the water medium, and sodium borodeuteride was chosen to compare with sodium borohydride as a source of the reducing agent. Adopting nuclear magnetic resonance (NMR) as a tool, the results were tentatively concluded that both dehydrogenation and cracking reactions occurred under ultrasound. It was also observed, in the case of the water medium without the presence of hydrogen sources, that the principle reaction is dehydrogenation accompanied with minor cracking. The cracking increases considerably only after a hydrogen source is introduced. Simultaneous cracking and dehydrogenation are involved at the expanses of the naphthenic hydrogen type in asphaltene of the reaction pathway scheme.