STRUCTURAL, SURFACE, AND CATALYTIC PROPERTIES OF A NEW BIMETALLIC V-MO OXYNITRIDE CATALYST FOR HYDRODENITROGENATION

A new bimetallic V-Mo oxynitride has been synthesized by temperature-p rogrammed reaction of a bimetallic oxide precursor with ammonia gas. T he surface properties of this new catalyst are investigated with tempe rature-programmed reduction (TPR), CO chemisorption, and Nz physisorpt ion. The catalytic activity of the material is measured in a three-pha se trickle-bed reactor at 3.1 MPa and 643 K with model liquid reactant s. The bulk characteristics of the oxynitride are studied by X-ray dif fraction analysis, Raman spectroscopy, and inductively coupled plasma (ICP) analysis. The new compound, of composition V2.0Mo1.0O1.7N2.4, ha s a face-centered cubic (fee) metallic structure arrangement, a surfac e area of 74 m(2) g(-1), and a CO uptake of 167 mu mol g(-1). Its cata lytic activity in hydrodenitrogenation is higher than that of the pure compounds VN and Mo2N and a commercial Ni-Mo/Al2O3 catalyst (Shell 32 4). TPR in hydrogen of the passivated oxynitride shows the formation o f H2O, N-2, and NH3 during activation and thermal stability to 830 K. The reactivity and TPR results indicate that the catalytic properties of the V-Mo oxynitride alloy are enhanced over those of the individual V and Mo nitrides, possibly due to a decrease in the binding strength of reactive intermediates at the surface.