Ni-Mo nitride catalysts: Synthesis and application in the ammoxidation of propane

Five different methods were used to prepare the Ni-Mo oxide precursors including sol-gel, rotary evaporation-microwave drying, co-precipitation, impregnation, and mechanical mixing. Ni-Mo nitride catalysts have been synthesized by temperature-programmed nitration of the oxide precursors in a flow of H2 and N2. The structure and physico-chemical properties of the Ni-Mo oxide precursors and their corresponding nitride catalysts were determined by X-ray diffraction, total nitrogen content analysis, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction, and their catalytic performance for propane ammoxidation was also tested. The catalytic activity and selectivity towards the formation of acrylonitrile over the Ni-Mo nitride catalysts are strongly dependent on the preparation methods for the oxide precursors. The N species in the Ni-Mo nitrides and their mobility and reactivity affect the selectivity for acrylonitrile. The Ni-Mo nitride prepared by co-precipitation, with the largest amount and more reactive N species, exhibited the highest catalytic activity and selectivity for acrylonitrile.

Graphical AbstractPrecursor preparation methods affect the structure and properties of nitrides. Lattice nitrogen species participate in propane ammoxidation reaction. The mechanism for propane ammoxidation over the Ni-Mo nitride is analogous to the Mars-van Krevelen mechanism.Figure optionsDownload as PowerPoint slide