Microwave energy can be used to promote a type of limited combustion synthesis.  We have combined the technique of microwave heating with the excellent gas-solid reactant contact of fluidized beds to prepare carbide and nitride nanolayers on early transition metal powders.  Transition metal carbides and nitrides can exhibit catalytic activity and are both technically and economically competitive with traditional noble metal catalysts for applications ranging from producing hydrogen for fuel cells to cleaning hydrocarbon fuels.  These compounds were prepared by fluidizing transition metal powders either alone in a reactant gas (e.g. nitrogen or ethylene) or together with carbon black in argon.  The resulting products were characterized with several microscopy techniques (XRD, TEM, EDS) and assessed for catalytic activity in the water-gas shift reaction.  The compounds that were prepared include Cr₂N, MoN, Cr₂C₃, Mo₂C, and WC. 

This work clearly demonstrates that it is possible to produce carbide and nitride overlayers on early transition metals with microwave-assisted fluidized bed synthesis.  The extent of reaction, however, varied from metal to metal.    Cr₂N was prepared more readily than MoN, but Cr₂N was less catalytically active.  Using ethylene rather than carbon black as the carbon source was a more effective technique to prepare carbides.  Mo₂C and WC overlayers were prepared with this method.  Of these prepared compounds, Mo₂C had the highest catalytic activity in the water-gas shift reaction.