Optimization of tungsten-based catalysts for the hydrotreatment of coal-derived liquids

The preparation and testing of tungsten-based catalysts for the hydrotreating of coal-derived liquids has been carried out. Catalyst performance was markedly affected by coke deposition, particularly in the top portion of the bed, and means of minimizing deactivation had to be developed. The importance of mass transfer in the systems was confirmed by the finding that catalyst compositions in the outer third of a catalyst pellet have most effect on performance. Tungsten-based catalysts were found to perform better than a commercial nickel-molybdenum-based catalyst. Surprisingly, cobalt-tungsten-based catalysts containing only small amounts of cobalt performed at least as well as some nickel-tungsten-based catalysts. Further testing is required to explore the potential of this type of catalyst.