Investigation on the increased stability of the Ni–Co bi-metallic catalysts for the carbon dioxide reforming of methane

Abstract

The carbon dioxide reforming of methane is one of the processes used to tackle global warming by reducing carbon dioxide, one of the most harmful greenhouse gases through the catalytic reaction with methane which produces syngas. Although the noble metals are good candidates for such a process, the cost and scarcity limit their uses. The non-noble metals on the other hand, with satisfactory activity and cost, are of interest except their stability against the coke formation, the main deactivation scheme during the dry reforming reaction. Therefore, the study of the enhanced stability found in the bi-metallic system of Ni catalysts via the introduction of Co was carried out in this work. The activity and coke resistance were studied on both mono and bi-metallic system of the Ni-based catalysts (10%wt) supported on γ-Al2O3-HY zeolite prepared via the sol-gel method. The activity testing was performed in a fixed-bed reactor with a unity feed volume ratio under atmospheric pressure at 973 K, where the Ni–Co bi-metallic system exhibits higher activity than both mono-metallic of either pure Ni or Co due to a higher number of active sites confirmed by the CO chemisorption. On the stability testing, the high stability was found on the bi-metallic system as verified by the time-on-stream testing. In addition, the higher reduction temperature for the bi-metallic system via the analysis using H2-TPR also suggested stronger metal-support interaction which may decrease the bonding strength of the coke on the surface leading to lower deactivation.