Study On Catalytic Conversion Model Compound Of Biomass Gasification Tar And Catalyst Deactivation

Under the grim situation of fossil fuel depletion and environmental pollution, research on development of clean renewable energy and improve energy efficiency is in depth around the world. Due to widely distributed, non-polluting, zero carbon dioxide emissions, biomass energy is expected to become the new energy which partial replace the fossil energy future.Biomass gasification is one of the most effective utilization of biomass. However, It produce particulate matter and tar during the gasification process that Clog pipes, damage equipment, is harmful to human health. So, purification technology of efficient, clean and energy conservation is an essential step in the biomass technology. This study select catalysts for catalytic removal of biomass gasification tar, do a detailed investigation on catalytic activity, selectivity, stability, life, anti-toxic, and catalyst coke deactivation.In this study, we chose Ni as the active component of the catalyst, olivine as the carrier, prepared by step-by-step impregnation method, use toluene as the biomass gasification tar model compounds, catalytic removal experiments are reacted in a fixed-bed micro-reactor. Experimental results show that the catalytic activity of the self-made Ni/olivine is excellent, but soon inactivation after reaction.In order to obtain better performance, Ce and Mg are modified on Ni/olivine as promoter, the experimental results indicate that Ni-Ce-Mg/olivine catalysts could improve the resistance to carbon deposition, enhance product gas quality and resist10ppm H2S poison at100mL/min for up to400min. Furthermore, the activity of catalysts was related to the steam/carbon (S/C) ratios; at S/C ratio=5, T=790℃, space velocity=782h-1and t=2h, the Ni-Ce-Mg/olivine system yielded89%toluene conversion,5.6L/h product gas rate,62.6mol%H2content and64%energy yield. The Ni-Ce/olivine catalysts exhibit a high selectivity towards CO2formation.Characterization of the catalysts was performed using X-ray Diffraction, Temperature-Programmed Reduction, transmission electron microscopy, and Nuclear magnetic resonance. Overall the performance of Ce and Mg promoted Ni/olivine catalysts is better than that of only Ce promoter and Ni/olivine alone. The catalyst of impregnating Mg, Ce and Ni onto olivine showed higher dispersion. Moreover, under the condition of low ratio of water to toluene, it had higher reaction activity and better ability to prevent coking. There is small amount of carbon deposition after reacted for7h, the mainly form of carbon deposited is a small amount of graphite carbon as well as its precursor.