The Effects of Ce and W Promoters on the Performance of Alumina-Supported Nickel Catalysts in CO2 Methanation Reaction

Abstract

The influence of Ce and W promoters on the performance of alumina-supported nickel catalysts in the CO2 methanation reaction was investigated. The catalysts were obtained by the co-impregnation method. Nitrogen low-temperature adsorption, temperature-programmed reduction, hydrogen desorption, transmission electron microscopy, X-ray diffraction, and photoelectron spectroscopy studies were used for catalyst characterization. An introduction of Ce and W promoters (1–5 wt %) led to the decrease in mean Ni crystallite size. Gradual increase in the active surface area was observed only for Ce-promoted catalysts. The increase in CO2 conversion in methanation reaction at low-reaction temperatures carried out over Ce-promoted catalysts was attributed to the increase in the active surface area and changes in the redox properties. The introduction of small amounts of tungsten led to an increase in the activity of catalysts, although a decrease in the active surface area was observed. Quasi in situ XPS studies revealed changes in the oxidation state of tungsten under CO2 methanation reaction conditions, indicating the participation of redox promoter changes in the course of surface reactions, leading to an improvement in the activity of the catalyst.

Advances on Catalyst Support Modification and their Effect on Fischer Tropsch Synthesis: A Review

“…It has been realized that a small change in the catalyst synthesis procedure might poses a substantial effect on the outcome of such a catalyst concerning catalyst structures, consequently having noteworthy differences in catalytic activity and selectivity, [161]. To further emphasize the importance of the catalyst preparation method, more latest experiments by Ai et al utilizing tungsten-doped Ni/Al2O3 catalysts, has shown that in CO methanation the addition of tungsten enhances reducibility and accordingly improves the number of active sites as well process performance but only when the appropriate preparation procedure is used [162].…”