Activity and Carbon Formation of a Low Ni-Loading Alumina-Supported Catalyst

Abstract

Carbon dioxide reforming of methane to synthesis gas over an alumina-supported 1% Ni-based catalyst has been investigated at atmospheric pressure. The reforming reactions were carried out at reaction temperatures of 500–800°C. The catalyst activity and stability, carbon deposition, and synthesis gas H2/CO ratio were determined. XRD, SEM, TGA and TPD techniques were employed to characterize the spent and fresh catalysts calcined at 900°C. Further experiments were performed at 600°C to reduce catalyst deactivation by coking. It was observed that, although increasing reaction temperatures from 500 to 600°C increased the formation of carbon, a further increase in reaction temperature to 800°C decreased the formation of carbon. The highest CH4 and CO2 conversion drops were recorded at 600°C. Experiments at 600°C revealed that addition of Ca promoter decreased coke formation and, therefore, enhanced the stability of the catalyst. Also, the combined partial oxidation increased the activity and reduced carbon formation. The optimum catalyst performance with respect to O2 addition was obtained with a feed containing 20% O2. On other hand, when the CO2/CH4 feed ratio was increased from 0.65 to 1.50, the drop in CH4 conversion with time-on-stream was reduced from 65 to 15%. The best catalytic performance was achieved with a space velocity of 33 mL/min · gcat.