UBC Theses and Dissertations
The effectiveness of bauxite residue in reducing biomass gasification tars Kim, Young Yoon
Biomass gasification converts the carbon and hydrogen in biomass feedstock into useful syngas. While there are notable commercial biomass gasification projects around the world, one of the major roadblocks in further technological advancement is the formation of the byproduct, biomass tar. Tar is a mixture of heavy condensable hydrocarbons that drops out from the gas as viscous liquid at lower temperatures. It easily condenses on cooler surfaces and plugs downstream equipment. It can also form aerosols and further polymerize into more complex structures. Catalytic tar reduction can reduce the tar in syngas by decomposing it into additional syngas, thereby improving the overall efficiency of the gasification process. Bauxite residue, an industrial waste rich in iron content, was investigated as an alternative catalyst for reducing biomass tars in the syngas generated from the Bioenergy Research Demonstration Facility at the University of British Columbia. An experimental unit was designed and commissioned to evaluate the catalytic activity of the bauxite residue. The bauxite residue catalyst was prepared and tested as untreated and as pretreated with calcination and pre-reduction processes. The pretreated bauxite residue was highly effective in reducing the biomass tars in comparison to the untreated catalyst. However, the spent-catalyst analysis revealed that the iron species oxidized back in the syngas environment over the duration of the experiment, demonstrating that a reducing environment is critical to maintain the catalytic activity of the bauxite residue.
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