Ni-Mg-La tri-metallic on alumina catalysts for steam reforming of a biomass gasification tar model compound

Magnesium and lanthanum oxide-promoted nickel/α-alumina catalysts were prepared by co- and sequential impregnation. XRD patterns of the catalyst presented main phases of Al2O3 and Ni, MgO, NiO, MgNiO2, (Ni, Mg) Al2O4, La2O3, La(AlO3). Metal oxides impregnation did not improved surface area but enlarged size of catalysts. Overall particle sizes and specific surface area were in the range of 14.11 to 40.17 μm and 4.37 to 8.41 m2/g. Steam reforming of toluene as tar model compound was performed at 500 to 800ºC. The highest gas production was achieved at 800ºC with heating value over 4 MJ/m3 and H2/CO between 2.49 to 2.77. 5%La2O3+5%MgO+10%Ni/Al2O3 co-impregnated catalyst exhibited the highest and more stable conversion of around 45% for conversion to CO and more than 60% for conversion to H2 after 480 min. Among sequential impregnated catalysts, 10%Ni-5%MgO-5%La2O3/Al2O3 showed early superior conversion but performance rapidly deteriorated after 120 min. Whisker and encapsulating carbon were found on used catalysts at 0.24 to 1.2 wt.% with the highest amount detected on 5%MgO-5%La2O3-10%Ni/Al2O3.