Utilization of carbon dioxide and methane via catalytic reforming reactions

Abstract

The overall purpose of this research study was to investigate new catalysts to produce synthesis gas via CO2 reforming of methane under optimized reaction conditions. The thesis consists of four parts. In the first part of the study; the purpose was to design and develop effective Pt-based bimetallic dry reforming catalysts supported on zirconia. Aiming to have bimetallic catalysts with enhanced performance properties, Ce was used as a promoter in order to increase the oxygen storage capacity of the catalysts via controlling the electronic structure of the metals over the support. The results have shown that introduction of 1 wt.% Ce to the Pt/ZrO2 catalyst by coimpregnation method led to superior catalytic activities and stabilities due to the to strong and extensive Pt-Ce surface interaction. In the second part of the thesis, Pt-Ni bimetallic catalysts supported on d- Al2O3 were designed and developed for carbon dioxide reforming of methane to determine an effective catalyst with optimum Pt/Ni metal composition assuring both high activity and stability. The different activity levels of the catalysts showed that the catalytic performances of bimetallic Pt-Ni samples strongly depended on the metal loading and Ni/Pt ratio. Among all the catalysts, 0.3Pt-10Ni catalyst with the lowest Ni/Pt ratio exhibited the highest catalytic activity and stability. By changing the Ni/Pt ratios of the catalysts and with the addition of small amounts of either oxygen or water to the feed stream, the catalysts’ resistance to coking reactions were also tried to elucidate. Based on the different performance and stability profiles of the Pt-Ni catalysts in part two in response to the changes in their Ni/Pt ratio as well as the reaction conditions, a kinetic study was performed in the third part of the study. In the final part of the research, the effect of addition of metal additives to Co/ZrO2 on both surface micro-structural properties and catalytic performance was investigated. The results have shown that La-modified catalyst exhibited high stability, but moderate activity. Ce-doped Co/ZrO2 displayed the highest activity among all the catalysts prepared and had a very limited activity loss.