Steam reforming of glycerol to hydrogen over ceria promoted nickel-alumina catalysts

Increased production of biodiesel in recent years has resulted in a surfeit of crude glycerol as by-product. This oversupply has triggered efforts to valorize glycerol to clean fuels such as hydrogen. In the present work, five kinds of nickel-alumina and ceria promoted nickel-alumina catalysts of different nickel and ceria loadings were prepared by wet impregnation method and tested for conversion of 30 wt.% glycerol in water. Characterization of fresh and spent catalysts were carried out with BET surface area, X-ray diffraction and scanning electron microscopy techniques. The reaction was conducted at temperatures from 550 °C to 800 °C, atmospheric pressure and weight hourly space velocity of 6.8-17 h−1. Thermodynamic simulations were also made for theoretical estimates of conversion and selectivity and for deciding suitable reaction conditions for experiments. Among the tested catalysts, 10Ni/Al2O3/5CeO2 was found to be the most efficient and stable for 16 h time on stream. Complete conversion of glycerol and hydrogen selectivity of 85.7% was obtained over this catalyst at 650 °C, against 95.9% thermodynamic value. Kinetic study was also done for this catalyst to get the reaction rate equation. Using power law model, the order of reaction and activation energy were determined to be 0.45 and 62.91 kJ/mol respectively.