Comparative hydrodenitrogenation activity of molybdenum, Co–Mo and Ni–Mo alumina-supported catalysts

The hydrodenitrogenation of pyridine is studied under high hydrogen pressure with and without sulfur in the gas phase on three alumina-supported catalysts: molybdenum, Ni–Mo and Co–Mo. Without sulfur, the three catalysts exhibit the same activity. In the presence of sulfur Ni–Mo is 2.5 more active than molybdenum and Co–Mo. Because of the design of the experiment, a full analysis of the reaction products is possible and shows that the difference of activity between the catalysts depends on the difference of acidity of their surfaces. A description on this difference is proposed.