Spontaneous Nano-ZrO2 Exsolution from Ni-Zr-O Mixed Oxides Enables Facile Fabrication of ZrO2/Ni Inverse Catalysts for Efficient COx Methanation.

Abstract

Ni-based inverse catalysts with nano-oxide dispersed on metallic substrates have emerged as promising candidates for low-temperature CO2 methanation, but it remains challenging in facile synthesis of well-dispersed oxide-metal interactions. Herein, a spontaneous oxide exsolution strategy for the fabrication of Ni-based inverse catalyst via monodispersed Zr species of Ni-Zr-O mixed oxide is demonstrated, where precisely tailored calcination and reduction of the mixed oxide enable in situ nano-ZrO2 segregation on the metallic Ni matrix. The formation evolution of inverse configuration is elucidated through comprehensive ex/in situ characterizations. X-ray photoelectron spectroscopy reveals the electron transfer between the exsolved ZrO2 and the Ni matrix, indicating the presence of metal-oxide interactions. The prepared ZrO2/Ni inverse catalyst achieves ~90% CO2 conversion and >99% CH4 selectivity at low-temperature of 200 °C, and also demonstrates excellent catalytic performance and dynamic operational stability in complex COx hydrogenation reactions, validating its industrial applicability under realistic syngas-equivalent feedstock conditions.