Progress of transition metal carbides in heterogenous catalysis

The progress in the study of early transition metal carbides in heterogenous catalysis, especially molybdenum and tungsten carbides is reviewed. The supported molybdenum or tungsten carbides or doped with a second metal shows excellent catalytic activity, especially for the hydrotreatment of petroleum distillates, such as hydrodenitrogenation (HDN), hydrodesulfurization (HDS) and isomerization, which makes them the promising substitutes for commercial catalysts. The preparation of carbide as well as its effects on the catalysis is also reviewed.