Thermocatalytic decomposition of propane for pure hydrogen production and subsequent carbon gasification: Activity and long-term stability of Ni/Al2O3 based catalysts

Ni/Al2O3 catalysts with nickel loadings from 10 to 40 wt.% prepared by wet impregnation have been tested for the thermocatalytic decomposition of propane in the temperature range from 700 to 1100 °C in a fixed bed reactor. Full conversion of propane was observed in all cases. The hydrogen yield was found to increase at higher reaction temperature, at lower temperatures significant quantities of CH4 were observed in the product gas. The Ni loading determined stability of the catalyst. After performing the catalytic decomposition reaction for a certain time, the carbon formed on the catalyst surface was removed by combustion with air. During this regeneration process carbon monoxide was always the main product. Repeated cycles of decomposition and regeneration were carried out. By using an automated control device, it was possible to ensure a continuous operation of the reactor for 65 h. For this period, stable H2 yield was observed with a catalyst containing 40 wt.% Ni supported by Al2O3. Fresh and spent catalysts were analyzed by BET, X-ray fluorescence (XRF), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Carbon formed by the decomposition reaction was analyzed by thermogravimetric analysis (TGA) and SEM.