Study On Hydrogen Production From Glycerol Steam Reforming Using Ni-based Catalysts And In-situ CO₂Sorption-enhanced Steam Reforming

Due to the shortage of conventional fossil fuels and environmental concerns, the development of biomass energy is expected to increase greatly in the future. As biodiesel fuel has become more attractive recently, proper application of glycerol produced during the production of biodiesel is an important issue nowadays. In this thesis, Ni based catalysts and CO2sorbents were developed. High-purity H2was obtained by in situ CO2sorption-enhanced glycerol steam reforming.By mixing different metal oxides and different metal salt solutions with rising pH technique, Ni based catalysts were synthesized and characterized by BET, SEM, TEM, XRD etc. The catalysts were evaluated by glycerol steam reforming and experimental factors such as temperature, steam to carbon ratio, feeding rate and space velocity were tested. The results showed that the catalysts with spinel prepared under900℃calcination had better performance on hydrogen production from glycerol steam reforming. Deactivation caused by carbon deposited was studied on the selected catalysts. TGA was used to study the oxidation carbon removal. The research on the model sensitivity for thermal decomposition was studied by an improved iterative Coats-Redfern method. The calculated kinetic parameters were given to describe the kinetics of oxidation carbon removal for catalyst regeneration.The Li2ZrO3based sorbents and CaO sorbent were studied for in situ CO2removal in sorption enhanced glycerol steam reforming. Li2ZrO3based sorbents were synthesized by the solid-state reaction method. An improved iterative Coats-Redfern method was firstly used to evaluate TGA nonisothermal sorption kinetics and the best fitted reaction model was selected. Sorption-enhaced steam reforming experiments were carried out on the selected catalysts and sorbents in a microreactor. Experiments for Ni-Al-Ca-0catalysts on sorption-enheced steam reforming were carried out. Reaction and regeneration process was also studied. The results showed that higher purity of hydrogen was obtained by the sorption enhanced method at the initial periods. To overcome the limitations of sorption enhanced steam reforming method, a promising continuous moving-bed system with the selected catalyst and sorbent for reaction and regeneration has been evaluated experimentally based on the results of reaction and regeneration cycles. High purity H2was continuously obtained at500-600℃under atmospheric pressure. The extended time of operation for high-purity hydrogen production was obtained to overcome the decay in activity of catalyst and sorbent, and the produced CO2could be collected.