Biomass Gasification Tar The Catalytic Converter

As a source of renewable energy, biomass is interested increasingly by the people. The technology of biomass gasification is one of the main utilization technologies of biomass. The produce gas of biomass contents 1.0-10.0% tar, which will be condensed on boilers, pipelines of transportation and the inlet devices of diesel engine in the process of utilization. It will take much time and money to remove them. In the dissemination of biomass technology, tar removal is a fatal weakness in the development of gasification technology. The immatured technology of tar removal and the environment pollution caused by tar are concerned increasingly by the society and relevant government departments. The main objective of this paper is study on catalytic removal of tar. Using benzene and toluene as the model compound, the steam reforming of tar has been performed with the synthesized catalysts of tri-metallic oxide compound of NiO, CeO₂ and Fe₂O₃ and the catalysts of olivine doped with NiO and CeO₂. The synthesized catalysts of tri-metallic oxide are prepared in the laboratory by coprecipitation with nitrate. The catalyst of Ni-Olivine is prepared by once or twice impregnation of raw olivine with nickel nitrate and cerium nitrate. Before acting, the two kinds of catalysts are reduced fully for 2.5h at 700℃ in the 160ml/min gas consisting of 50% H₂ and 50% N₂. The steam reforming reactions of benzene or toluene are performed under the following reaction conditions: Benzene's injection rate is equal to 1.7 ml/h (1.5 g/h), toluene's injection rate is equal to 1.8ml/h, the catalyst volume is equal to 0.5 ml, space velocity is equal to 862 h^-1, S/C ratio is equal to 5 and reaction temperature is 700, 750, 800 and 820℃. The gas composition such as H₂, CH₄, CO and CO₂ are investigated by GC. The performance of the two series of catalysts was evaluated by the conversion ratio of benzene or toluene. In addition, the steam reforming reaction of the commercial catalyst ICI46-1 was performed under the same reaction conditions and its performance was compared with the two series of catalysts. The results are as follows: First, the synthesized catalysts of tri-metallic oxide are active to the steam reforming reactions of benzene as same as catalyst ICI46-l.With the increasing of reaction temperature, the benzeneconversion increases and achieves 80% at over 800 °C. Moreover, compared with commercial catalyst ICI46-1, it has less carbon deposition and less methane in the produced gas. Second, the catalysts of Ni-Olivine are active to the steam reforming reactions of benzene and toluene. The benzene conversion can achieve over 70% at the temperature of over 800 °C. Compared with the other two, the catalyst of Ni-Olivine doped with CeC>2 is more active to the steam reforming reactions of benzene and toluene and can enhance the resistance to coke formation.These results show:The synthesized catalysts of tri-metallic oxide compound of NiO> CeO2 and Fe2