Tungsten catalysts, fluorine effects

Molybdenum- and tungsten-based hydrotreating catalysts supported on AI2O3 are widely used in the industry for HDS and HDN processes. Cobalt and nickel are the promoters of choice for HDS and HDN catalyst system based on MS2 (M = Mo or W), and their presence greatly increases both HDS and HDN activity. For HDN, Ni is the promoter of choice, whereas Co is preferred for HDS. Other additives, such as fluorine, chlorine, boron, and phosphorus, have been incorporated into both promoted and unpromoted MoS2-type catalysts with beneficial effect on HDN and HDS processes [116],... 

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