Catalytic desulfurization of dibenzothiophene using nickel supported on cross-linked polystyrene-PPh3 catalysts

Nickel catalysts supported on a cross-linked polystyrene-PPh3 resin were easily prepared in different oxidation states (0 and II) and used (0.1 mol% Ni) in conjunction with MeMgBr to achieve the desulfurization of dibenzothiophene (DBT), resulting in the formation of 2,2′-dimethylbiphenyl as the sulfur-free product (100%). The recycling of these catalysts was addressed in consecutive runs, from which a decrease in catalytic activity was observed within the recycling cycles. Comparison of SEM micrographs of the catalysts before and after the desulfurization process confirmed a decrease in the size of the polymeric resin particles as a result of their progressive dissolution into the organic phase, the latter being the major cause of the decrease in the catalytic activity, associated with gradual loss of the nickel catalysts by leaching.