Insights on the Highly Stable and Coke-Resistant Nickel/Zirconia Nanocatalyst for the Methanation of Carbon Dioxide.

The heat treatment condition has been known to have significant influence on the catalysts applied in high-temperature application. In this work, after studying the effect of Ni loading on ZrO2 in CO2 methanation reaction, the effect of calcination and reduction treatment on the characterization and catalytic activity was investigated. The catalysts were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis-DSC, isotherm N2 adsorption, H2 temperature program reduction, CO2 temperature program desorption and Raman spectroscopy. By studying different nickel loading, heat treatment temperatures and duration, these factors were found out to have correlation with the ZrO2 phases formation (tetragonal ZrO2 phase and monoclinic ZrO2 phase). Changing the calcination and reduction condition can alter the surface morphology, ZrO2 phase composition, the crystal sizes of ZrO2, NiO and Ni, as well as metal–support interaction, which can further improve the performance of the catalysts. Suitable heat treatment mode showed the ability to induced higher catalytic conversion of CO2 (70% at 400 °C) in the CO2 methanation. The superior catalytic activity was subjected to the enhanced reducibility of NiO species and the improved Ni dispersion and subjected to the co-existence of m-ZrO2 and t-ZrO2. Furthermore, the as-synthesized Ni/ZrO2 catalyst with higher specific surface area (26.2 m2/g) than several other literature's catalysts and an apart of Ni embedded in the ZrO2 pores exhibited good stability and high coke resistance, subjected to a 2.041% coke deposition after 100 h on stream. [ABSTRACT FROM AUTHOR]