(365f) Production of Fisher-Tropsch Liquids From Biomass-Derived Syngas

Depletion of fossil oil resources, global climate change and national security concerns have made the development of alternative energy increasingly important. Compared to other alternative energy choices, the production of energy and chemicals from biorenewable resources, such as biomass, has attracted increasing research interests in recent years due to the vast potential availability of biomass materials and the availability of existing technologies that potentially enable the production of energy and chemicals in commercial scales in shorter time period. Center for Sustainable Environmental Technologies (CSET) is a research organization at Iowa State University (ISU) that has been working on promoting, developing and demonstrating thermochemical technologies such as gasification and fast pyrolysis, and catalytic upgrading processes, for the production of fuels, chemicals, and energy from biomass. While for many years focuses have been given to gasification and fast pyrolysis technologies for converting biomass into synthesis gas and bio-oil, respectively, in the past two years, CSET researchers have been working on the development of catalytic processes for upgrading syngas and bio-oil into value-added products. This paper is to report the results of research work that has been performed at CSET on the production of liquid fuels from biomass-derived syngas by using Fischer-Tropsch Synthesis (FTS) technology. The work included synthesis and characterization of an FTS catalysts and the demonstration of FTS fuel production from a fixed bed reactor. One FTS catalyst used for this study is a cobalt-based catalyst which was prepared by using zirconium and γ-alumina as the promoter and support, respectively. Previously, the catalyst has been successfully synthesized, characterized and tested for its performance by using a high pressure slurry reactor constructed at CSET. In order to improve efficiency and liquid selectivity for FTS process, a novel catalyst containing the same active components but supported on SBA-15 based material was developed recently. Since SBA-15 mesoporous silica has large surface area and well defined nanostructures, reaction capacity and shape selectivity of this catalyst is expected to be much better. In this work, the relationships between catalyst property and hydrocarbon fuel production will be thoroughly investigated. The catalysts will be engineered to improve thermal dissipation in the catalyst bed since FTS reaction is highly exothermic. In addition, a comparison between the results of FT synthesis on a slurry reactor and those on a fixed-bed reactor at similar operating conditions will be studied as well. Finally, the effect of impurities in synthesis gas on the catalyst performance will be addressed. This final discussion will relate to the need addressing a compromise between development of robust FTS catalyst and on the development of synthesis gas technology in order to obtain an FTS process that is most sounds techno-economically.