The sulfur levels in diesel have been increasingly restricted in the world out of environmental considerations. Environmental regulations to be applied by 2006 in Europe, US and other countries, for instance, limit the level to less than 15 ppm. To meet these stringent conditions novel desulfurization processes are needed to ensure sustainable and economically acceptable technology.
A research team led by Prof. Li Can from the CAS Dalian Institute of Chemical Physics has made progress in reducing the amount of sulfur in diesels from several hundred ppm to only a few ppm. This work has been remarked recently by the journal of
Green Chemistry (2004, 6, G63) as "a research highlight of 2004 in Green Chemistry."
The CAS team utilized a kind of highly efficient amphigenous catalyst to anchor on the interface of oil-water emulsions, which can catalyze selectively the sulfur-containing compounds in the diesels to convert into sulfons by reacting with stoichiometric H2O2 under mild conditions. Then the sulfons can be extracted by suitable extractants. In this way, the sulfur content of diesels can be lowered to less than 0.1 ppm, while the diesel recovery rate is higher than 98%.
