Ethanol dry reforming over Ni supported on modified ceria-zirconia catalysts– the effect of Ti and Nb dopants

In this work complex metal-oxide catalysts with the general formula 5 wt% Ni/Ce0·75Zr0.25-x(Nb,Ti)xO2-δ were synthesized by the solvothermal method using supercritical alcohols followed by nickel deposition. The catalysts were characterized and studied in ethanol dry reforming reaction (EDR) in the temperature range 600–750 °C. XRD and TEM showed that the synthesis method provides incorporation of doping cations into the ceria-zirconia fluorite structure, leading to mixed oxides formation. The effect of doping cations on structural and surface properties of 5 wt% Ni/Ce0·75Zr0.25-x(Nb,Ti)xO2-δ and activity in the EDR reaction was investigated. Oxygen deficiency δ increases with the introduction of titanium and niobium cations, which contributes to the bifunctional reforming mechanism implementation with rapid oxidation of coke precursors and activation of СО2 at surface oxygen vacancies. TPO-O2 analysis after reaction showed no carbon formation above 700 °C, and a few carbon deposits (not exceeding 4%) even after significant catalyst deactivation at 600 °C.