Synthesis, characterization and catalytic properties of bimetallic ZrMo2Nx-Mo2N nitrides of high surface area

A set of bimetallic nitrides, ZrMo2Nx-Mo2N, of high specific surface area up to 132 m(2)/g has been synthesized by temperature programmed nitriding (TPN) mixtures of Zr- and Mo-containing compounds with ammonia. Two series of precursors have been studied using XRD, SEM and FT-m. It is found that the structure and composition of the end-products depend on the properties of the precursors and these, in turn, are influenced to a large extent by the preparation method of the precursor, i.e. using impregnation or using coprecipitation. The end-catalysts obtained from precursors prepared by impregnation are composed of ZrO2-Mo2N while those from precursors prepared by coprecipitation consist of ZrMo2Nx-Mo2N. XRD and SEM results reveal that the characteristic platelet structure of MoO3 is damaged upon the introduction of the second metal component by coprecipitation, but is retained when using impregnation. The catalytic activities of the bimetallic nitrides for the hydrogenation of cyclohexene and the hydrodesulfurization of thiophene are found, under medium pressures (3.0 MPa), to compare favourably with those of a commercial sulfided NiCoMo/Al2O3 catalyst and unsupported gamma-Mo2N. H-2-TPD results indicate that the bimetallic nitrides possess a more extensive capacity for hydrogen adsorption in low temperature states. (C) 1998 Elsevier Science B.V. All rights reserved.