During HDS, the hydrocarbon feed and hydrogen gas are passed over a fixed-bed reactor containing the catalyst. The reaction typically occurs at temperatures ranging from 300-400°C and pressures between 30-130 atm. The desulfurization process can be summarized in the following steps:
Adsorption of sulfur-containing molecules on the catalyst surface. Dissociation of hydrogen molecules into atomic hydrogen on the catalyst. Reaction of atomic hydrogen with adsorbed sulfur compounds to form H2S and hydrocarbon fragments. Desorption of H2S and desulfurized hydrocarbons from the catalyst surface.
