Hydrogen Production via Oxidative Steam Reforming of Biodiesel By-products over Ni/CeO2-ZrO2/Al2O3 Catalyst

Yellow glycerol and crude glycerol, by-products of biodiesel, are renewable resource that can be used for sustainable production of hydrogen. The oxidative steam reforming of biodiesel by-products over Ni/CeO2-ZrO2/Al2O3 catalyst were investigated and the effluents from reforming of both by-products were compared with that of pure glycerol. Preliminary analysis of yellow glycerol showed that there were methanol and fatty acid methyl esters in it whereas the presence of potassium (K) and sodium (Na) was observed in crude glycerol. The catalytic activity of Ni/CeO2-ZrO2/Al2O3 catalyst was studied isothermally under atmospheric pressure at water-to-glycerol and oxygen-to-glycerol molar ratio of 9:1 and 0.5:1, respectively. Under these conditions, the glycerol was reformed to H-2, CO2, CO and CH4 with small amount of C-2 gas products that were measured by gas chromatograph. The results showed that the yellow glycerol was completely converted in gas phase and provided hydrogen yield and selectivity at 71% and 72%, respectively, whereas crude glycerol was nearly completed to convert in gas phase and gave the lowest hydrogen yield and selectivity at 37% and 42%, respectively because of the presence of coke formation. Therefore, the potential to produce hydrogen gas with low price feedstock like yellow glycerol was highly recommended with respect to pure glycerol.