Collect. Czech. Chem. Commun. 1999, 64, 735-746

Synergism Between Ni and W in the Ni-W/C Sulfide Catalyst in Hydrodenitrogenation of Pyridine and Hydrodesulfurization of Thiophene

Daniela Gulková and Miroslav Zdražil*

Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojová 135, 165 02 Prague 6, Czech Republic


Parallel hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene was studied over active-carbon-supported Ni, W, and Ni-W sulfide catalysts at 2 MPa and at 280 and 320 °C. Synergism between Ni and W was observed both in HDN and HDS reactions: the activity of the Ni-W catalyst was higher than the sum of the activities of the Ni and W catalysts. However, the synergistic increase in activity was much higher in HDS than in HDN. This led to a characteristic shift in the HDN/HDS selectivity, which was strongly shifted to the HDS side over the Ni-W catalysts as compared with the Ni and W catalysts. HDS was faster than HDN over the Ni-W catalyst, the rate of both reactions being about the same over the Ni catalyst and HDN being faster than HDS over the W catalyst. The selectivity of all the catalysts was shifted to the HDN side with decreasing temperature. The data are a new example for generalisation of the rule that the synergism in activity of bimetallic sulfide Co-Mo, Ni-Mo, and Ni-W catalysts is higher in HDS than in hydrogenation and HDN.

Keywords: Hydrodenitrogenation; Hydrodesulfurization; Ni-W sulfide catalyst; Heterogeneous catalysis; Nickel; Tungsten; Hydrogenation.