Supported ZnO catalysts for the conversion of alkanes: About the metamorphosis of a heterogeneous catalyst

ZnO could be a suitable catalyst for the oxidative conversion of CH4, C2H6 and C3H8. However, the main drawback is its thermal instability. Therefore, ZnO supported on ZrO2, TiO2, γ-Al2O3 and SiO2 was investigated for the oxidative dehydrogenation of propane and ethane, and the oxidative coupling of methane. The stability of the supported ZnO is partially improved, but ZnO reacts with the support material, forming new compounds (Zn-zirconates, -titanates, -aluminates and -silicates), which already occurs below reaction temperature. This might also be the case for many other heterogeneous catalysts.