Surface Properties and Active Sites of Nitrided Mo/Al2O3 Catalysts for the Hydrodenitrogenation of Carbazole

The active sites for the hydrodenitrogenation of carbazole for a series of low loading nitrided Mo/Al2O3 catalysts have been investigated by a combination of CO adsorption, pyridine adsorption, temperature-programmed surface reaction with hydrogen and fractal analysis. Accordingly, the active sites for different stages of reaction have been determined. It is proposed that carbazole adsorbs on the edge of molybdenum nitride crystallites where it is hydrogenated to perhydrocarbazole which desorbs, migrating to nitrogen deficient nitrogen planes where it undergoes C–N hydrogenolysis.