Study On Raney-Ni Catalyst For Hydrogen Production From Reforming Of Glycerol

With the development of fuel cell technology and the great increase ofbiodiesel production in recent years, hydrogen production by catalyticreforming of glycerol has been paid a great attention in the academic andindustrial world. In this paper, the process and performances of glycerolcatalytic reforming reaction and different supported catalysts werestudied systematically to develop a hydrogen production method, whichcan be used directly for hydrogen fuel cell.Firstly, the influence of the temperature, feed concentration, catalystloading and feed flow rate on the hydrogen production by steamreforming (SR) of glycerol over Raney-Ni catalyst at ambient pressurehas been studied in this paper. The results show that the Raney-Nicatalyst has high catalytic activity and good stability in the steamreforming process even at relatively low temperatures. At the temperatureof 280℃, with a feed concentration of 5wt% and flow rate of 0.5 mL/min, the carbon conversion and the selectivity of H₂ are 99.9% and 80.69%,respectively. The selectivity of CO is remarkably low which can meet therequirement of hydrogen fuel cell.Secondly, the hydrogen production by aqueous-phase reforming(APR) of glycerol over Raney-Ni catalyst was studied. The influences oftemperature, glycerol concentration and LHSV were investigated. It isshown that the Raney-Ni catalyst has good catalysis to the hydrogenproduction by aqueous-phase reforming (APR) of glycerol in subcriticalwater. In the near critical region, with the increase of reactiontemperature, the carbon conversion and the hydrogen yield increaserapidly, and CO concentration at a very low level can be obtained in theresulted gas. This makes it possible that the gas produced can be used inhydrogen fuel cell directly. At the temperature of 350℃, the carbonconversion reaches nearly 100%, and the hydrogen yield reaches 91.33%.Finally, the performenance of Ni/γ-A1₂O₃, Ni/La₂O₃ and Ni/ZrO₂ ascatalysts for glycerol steam reforming has been studied in comparisonwith that of the Raney Ni. These catalysts were prepared by equal volumeimpregnation method using nickel nitrate as precursor andγ-A1₂O₃,La₂O₃ and ZrO₂ as the supports．The effect of supports on catalyticperformance was investigated. The characterization means, includingBET, XRD and SEM, are utilized to optimize catalysts'composition. Theresults show that the catalytic performance has a closely relation between the acid-base properties and the redox properties of the supports. Theselectivities for hydrogen followed the order:γ-A1₂O₃ < ZrO₂ < La2O₃. Inthe near-critical temperature of water, Ni/La2O3 has very high catalyticactivity, and it can not only led to a very low CO concentration in the gasproduced, but also has a better inhibition action to the reaction ofmethanation and to the accumulation of carbon on catalysts. It is acatalyst deserving more research on the hydrogen production by steamreforming of glycerol.