(437a) Stability, Activity and Selectivity Study of a Precipitated Iron Catalyst for Biomass to Liquid Fuels Via Fischer-Tropsch Synthesis

The production of clean fuels from biomass via Fischer-Tropsch synthesis (BTL-FT) has become more and more attractive. FT, as a proven technology to transform under-utilized hydrocarbon resources into valuable alternative fuels and chemicals, is at the heart of the BTL process. Our research group of Material and Process Synthesis (MaPS) has developed a simplified small scale BTL-FT process which sets its own requirements of the catalyst to make the FT process more feasible and operable, such as the catalyst should have a high water-gas shift (WGS) activity to adjust the feed gas H₂/CO ratio to near to two. Because the Iron-based catalysts are low cost and demonstrate high activity for both FT and WGS reactions, they match the requirements of our new BTL-FT process.

The viability of the FT process depends on three key factors, the life, the activity and the product selectivity of the catalyst. The present work focuses on the investigation of the catalytic performances of an iron based FT catalyst for the conversion of renewable fuels from biomass over both short term and long term operations. A precipitated iron based catalyst was prepared. And a large number of FTS experiments have been conducted using the syngas - a mixture of CO/H₂/CO₂/N₂ - which is simulated as a syngas derived from biomass gasification. Three fixed bed reactors were used in this study: (1) Reactor One was used to expose the effect of operating conditions (different temperature, pressure and flow rate) on the catalyst activity and product selectivity during the short term FTS; (2) Reactor Two and Reactor Three were used to investigate the stability of catalyst. Reactor two was reduced by syngas and the other was activated by H₂. After catalyst reduction, the same FT reaction procedures were carried out and the reactions have been running for a long period of more than 7 month for both of Reactor Two and Reactor Three.

The results of this investigation are intended to provide valuable information, such as, if this catalyst can remain active at a relatively high CO₂ and N₂ contents syngas; whether this catalyst have a high WGS activity; How does the catalyst activity and selectivity changing during the life time running? Furthermore, if the catalyst can be activated by the same syngas used for FTS, we can further simplify our new BTL-FT process. The results would make a valuable contribution to the design of BTL-FT process and make it more economical and industrially applicable.