Catalytic Steam Reforming of Model Oxygenates of Bio-oil for Hydrogen Production Over La Modified Ni/CeO2-ZrO2 Catalyst

Catalytic steam reforming of model oxygenates of bio-oil for hydrogen production was studied over La modified Ni/CeO2-ZrO2 catalysts. The catalysts were prepared by an impregnation-co-precipitation method and characterized by various characterization techniques. Characterization results revealed that a homogeneous CeO2-ZrO2-La2O3 (CeZrLa) solid solution was formed during support preparation and the Ni-impregnated catalysts demonstrated strong metal-support interaction. The hydrogen selectivity for the catalyst doped with 5 wt% La2O3 was significantly higher than that for other La content, and CO and CH4 selectivity also reduced. Conversion showed a sharp rise with increasing temperature from 600 to 800 degrees C, whereas hydrogen yield and selectivity exhibited maxima at 700 degrees C. At higher temperature, conversion increased due to steam reforming of oxygenates, while hydrogen yield decreased since the water gas shift reaction proceeds in the reverse direction. Increasing the space-time from 350 to 700 g(cat) s/g(bio-oil), conversion increased from 60 to 85 % and hydrogen yield increased from 42 to 70 % due to the availability of greater contact time of the reactants with the catalyst. No significant decrease in selectivity or conversion was observed for 20 h, indicating that the Ni/CeZrLa (5) catalyst is quite stable. In the spent catalyst obtained after reaction, there is evidence of formation of La2O2CO3, which plays a key role in coke gasification and prolonged activity of the catalyst. Negligible coke deposition was found for the spent Ni/CeZrLa (5) catalyst compared to the undoped catalyst. The results revealed that the presence of lanthana helps in enhancing catalyst life by providing resistance to coking.