Catalytic Reformation Of Glycerol For Hydrogen Production In Subcritical Water

The development of downstream products for biodiesel byproduct glycerol has been investigated in many aspects at home and abroad in recent years. As a high-efficiency and clean energy, the study of hydrogen production from glycerol has been paid much attention. At present, it focuses mainly on the steam reforming, the partial oxidation, the autothermal reforming, the aqueous phase reforming and the supercritical water reforming. Aqueous phase reforming has the advantages of low reaction temperature and low energy consumption. But there exist problems such as low carbon conversion, catalyst deactivation and using precious metal catalyst etc.. It is significant to carry out further investigations to improve the hydrogen production efficiency, to enhance the catalyst stability and to replace the precious metal catalysts with the ordinary ones.Using a fixed-bed reactor, hydrogen production from glycerol refoming in subcritical water has been studied systematically. The Ni based catalysts were used in the catalytic reforming reaction. The effect of the reaction conditions, the properties of catalysts on catalytic activity for the subcritical water reforming reaction has been investigated.The catalyst of Ni/Al2O3was prepared by incipient impregnation method. The effect of the temperature (250℃～360℃), pressure (1.05～1.5), LHSV (8.657h-1and17.314h-1), particle size (40～100mesh), the amount of catalyst (2.5g～6.5g), Ni loading (5wt%～20wt%), glycerol concentration (3wt%～15wt%), and different feedstocks (Methanol, ethanol and glycerol) was examined. The reaction has a relatively high activity at the temperature of360℃, the pressure of1.05, LHSV of8.657h-1,the particle size of40～60mesh, the catalyst amount of3.5g, Ni loading of10wt%, glycerol concentration of3wt%.Four different Ni based catalysts:Ni/MgO, Ni/Al2O3, Ni/CeO2and Ni/TiO2were studied. The results indicate that the nickel catalysts with alkaline supports such as MgO and Al2O3give better catalytic activity than the other two. In the temperature range320～360℃, the conversion of glycerol increases as the temperature increases. At the temperature of360℃, the conversion rate of glycerol and the selectivity of hydrogen are43%and81%, respectively, by using the catalyst Ni/MgO and are39.4%and92.3%, respectively, by using the catalyst Ni/Al2O3. The selectivity of CO maintains at relatively low level in the temperature range studied.