Heteropolyacids as effective catalysts to obtain zero sulfur diesel*
Alberto de Angelis1, Paolo Pollesel1, Daniele Molinari1, Wallace O'Neal Parker Jr.1, Alessandra Frattini2, Fabrizio Cavani2, Susie Martins3, and Carlo Perego1
1Eni, Refining and Marketing Division, via F. Maritano 26, San Donato Milanese, Italy; 2University of Bologna, viale Risorgimento 4, Bologna, Italy; 3UOP, 25 East Algonquin Road, Des Plaines, IL 60017, USA
Abstract: This paper deals with the catalytic properties of different supported heteropolyacids (HPAs), both molybdenum- and tungsten-based, in the oxidative desulfurization process of diesel. We are jointly developing a new oxidative desulfurization process, aimed at reducing the sulfur content in diesel to less than 10 ppm (parts per million) using in situ produced peroxides. In this new process, high-molecular-weight organosulfur compounds, such as 4,6-dimethyl-dibenzothiophene (DMDBT), difficult to be eliminated by conventional hydrodesulfurization, are oxidized to the corresponding sulfones and subsequently removed by adsorption. Molybdenum-based HPAs, with Keggin structure, proved to be the most active and selective catalysts for oxidizing DMDBT with on-stream lifetimes exceeding 1500 h time on stream (t.o.s.).
Keywords: heteropolyacids; desulfurization; diesel; air pollution; molybdenum.
*Pure Appl. Chem. 79, 1831-2100. An issue of reviews and research papers based on lectures presented at the 1st International IUPAC Conference on Green-Sustainable Chemistry, held in Dresden, Germany, 10-15 September 2006.