Transition Metal Catalysts For Hydrodesulfurization Reactions Applied To Petroleum Industry

Catalysis plays a fundamental role in petroleum refining and basic petrochemical industries creating new routes in the development of industrial processes. Moreover, catalysis has become indispensable to the solution of environmental pollution problems and therefore on public health. World wide concerns for preservation of the environment has motivated the development of Green catalyst based technologies, to achieve a better utilization of petroleum resources and demands for cleaner transportation fuels. These environmental concerns have led to increasingly drastic regulations on sulfur, nitrogen and aromatics content in fuels. Sulfur content in the motor and diesel fuels is continuously reduced by regulations to lower levels. The current specification in Europe and USA calls for maximum sulfur content of 50 ppm in gasoline and diesel by 2005 and this level will be reduced to below 10 ppm by 2010. These facts have created a demand for better and more effective catalysts and catalytic processes to provide cleaner fuels. Transition metal sulfide (TMS) catalysts play an important role in the petroleum industry. TMS are unique catalysts for the removal of heteroatoms (N, S, O) in the presence of large amounts of hydrogen. Hydrodesulphurization (HDS) of petroleum feedstocks are commercially achieved with MoS2 or WS2 supported on alumina and promoted by Co or Ni. Co-promoted catalysts are mainly used for HDS, whereas Ni-promoted catalysts are superior in hydrodenitrogenation (HDN) and hydrogenation (HYD) reactions. Catalysts currently employed need to be improved to satisfy the imminent restrictions that require the removal of the most refractory species, mainly alkyl-substituted polyaromatic thiophenes. In the current work a new family of unsupported TMS catalysts is presented with volumetric efficiencies significantly greater than current commercial catalysts. The scientific basis behind the activity improvements and the progress toward commercialization is presented