Supported (NiMo,CoMo)-carbide, -nitride phases: Effect of atomic ratios and phosphorus concentration on the HDS of thiophene and dibenzothiophene

A study on the catalytic properties of the transition metals (Ni,Co,Mo)-carbides, -nitrides for thiophene and dibenzothiophene hydrotreating was conducted. The (Ni,Co)-Mo carbides and the corresponding (Ni,Co)-Mo nitride phases showed a catalytic activity higher than conventional bimetallic (Ni,Co)-Mo sulfides. In addition, a study was done on the effect of the atomic ratios, i.e., 0.1 (less than) M+/(M+ + Mo) (greater than) 0.9 where M+ stands for Ni or Co, and the concentration of promoters such as phosphorous, which was a structural stabilizing agent. The catalytic performance of the bimetallic NiMo and CoMo carbides and nitrides was studied using thiophene and dibenzothiophene hydrodesulfurization (HDS) as model reactions at 623 K and P = 1 atm. The catalytic activity of the dispersed carbide and nitride phases on the alumina carrier was more significant than that of the reference catalysts, alumina supported NiMo-S and CoMo-S. The metallic character of the NiMo and CoMo carbides was evidenced by their higher hydrogenation activity in thiophene HDS, while the nitrides favored both hydrogenation and hydrogenolysis type reactions.