Selective synthesis of tungsten carbide phases W2C and WC as hydrogenation catalysts

•Isothermal carburization of WO3 precursors allows phase control of tungsten carbide.•Design of Experiments shows temperature and silica stabilizer to be key parameters.•Phase composition (W2C vs. WC) adjustable over wide range, only minor amount of W.•Small crystals and low surface energy thermodynamically favor W2C relative to WC.•Activity for butyraldehyde and for toluene hydrogenation increases with W2C content.