Investigating the influence of Ni-CexZr1XO2 interaction on oxygen vacancy and catalytic behavior of Ni/CexZr1XO2 catalysts for ethanol steam reforming

Abstract

Ni/CexZr1−xO2 catalysts were synthesized with two types of CexZr1−xO2 solid solutions to understand the role of oxygen vacancy in ethanol steam reforming (ESR). The cubic Ce0.93Zr0.07O2 (CZ) contained more oxygen vacancies on the surface and in the lattice structure than the tetragonal Ce0.07Zr0.93O2 (ZC). Even though the Ni-CexZr1−xO2 interaction basically increased the surface oxygen vacancy (OVS) on the interfacial region, it also induced different bulk oxygen vacancy (OVb) behavior: no OVb over Ni/ZC and no change over Ni/CZ. In the ESR, active oxygen species (Ox) generated on the OVS simultaneously involved SR, and water gas shift reaction (WGS) to produce H2. Zero OVb over Ni/ZC influenced the Ox involving–reaction routes, resulting in the limitation of WGS and the high TOF values at 750 °C. Furthermore, since the OVb played a significant role as the Ox carrier, Ni/CZ showed the highest H2 production rate in the ESR at 750 °C.