Catalytic Steam Reformation Of Glycerol For Hydrogen Production

Due to the rapid growth of biodiesel industry, a reasonable and efficient use of its by-product glycerol to develop high value-added products has become an urgent problem and task. Meanwhile, the breakthrough of fuel cell technology promotes the development of hydrogen industry. Therefore, it is significant and prospective to use glycerol as raw material to produce hydrogen for the fuel cell. In this paper, the catalytic steam reforming process of glycerol was studied systematically to develop a hydrogen production method, in which the hydrogen obtained can be used directly for a hydrogen fuel cell.First, the performance of Ni/La2O3, Co/La2O3, Cu/La2O3, Fe/La2O3catalysts on the glycerol steam reforming for hydrogen has been studied. The result showed that nickel catalyst gave a much higher conversion of glycerol under same conditions. A100%conversion of glycerol could be achieved at350℃over Ni/La2O3. What’s more important is that the nickel catalyst gave a much higher hydrogen yield than other catalysts, and extremely low one of carbon monooxide.Secondly, the performance of nickel catalysts with different supports (Ni/Al2O3, Ni/SiO2, Ni/ZnO, Ni/MgO, Ni/dolomite, Ni/La2O3) on the glycerol stream reforming for hydrogen has been investigated. The results indicated that the catalytic performance of these catalysts significantly depended on the acid-base properties of the supports. The catalysts with base oxide supports (Ni/dolomite, Ni/MgO) gave a much higher selectivity of hydrogen and conversion of the glycerol than those with acid oxide supports (Ni/SiO2, Ni/Al2O3). In particular, the nickel catalysts supported on La2O3gave the best catalytic activity for the steam reforming reaction of glycerol. Thirdly, the KOH modified Ni/La2O3catalyst and its performance on the glycerol steam reforming have been studied. The results showed that the catalyst modified by addition of KOH gave a similar conversion rate of glycerol, but it could obviously supress the methanation, give very high actitivty for the water-gas-shift reaction and led to a very high yield of H2. With a feed concentration of30%wt glycerol, a very high yield for H2(99.9%) and entremely low one for CO (selectivity0.2%) were achieved at a reaction temperature of400℃. It is to note that after modification the catalyst is still very stable. The high catalytic performance of the catalyst could last for over125h with a30%wt glycerol feed and at400℃Finally, the kinetics of the glycerol steam reforming reaction over KOH modified Ni/La2O3catalyst has been investigated. A kinetic model was proposed, in which the activation energy (Ea) of the overall reaction is104.964kJ, the reaction order of glycerol is0.5951, and that of steam is1.3336. It is indicated that the increase in steam partial pressure is advantageous to the reaction. The kinetic model proposed agrees well with the experimental results.