Thesis (M.Eng.)--Chulalongkorn University, 2007

This work investigates the catalytic performance under periodic operation for combined carbon dioxide reforming and partial oxidation of methane over an industrial steam reforming Ni/SiO₂.MgO catalyst. Various analytical techniques including BET surface area measurement, SEM, XRD, and TPO were employed to characterize the spent catalysts. It was shown that this reaction was able to suppress carbonaceous deposition on catalyst surface at reaction temperatures of 650 and 750℃ without any significant loss of activity for 12 cracking/regeneration cycles. Carbon dioxide with oxygen could fully regenerate the catalyst when operating at high oxygen content and reaction temperature, thus a lesser amount of coke was observed. However, the addition of oxygen caused slightly decrease in carbon dioxide conversion. The optimal performance for periodic operation was found under the condition with 5 min of the cracking step followed by 5 min of the regeneration step at 650℃ with CO₂/O₂ ratio about 9/1. Additionally, it was found that the periodic operation provided the hydrogen yield close to that of the steady state operation at 650℃.