(68b) Investigation of Effects of Coal and Biomass Contaminants on the Performance of Water-Gas-Shift and Fischer-Tropsch Catalysts

TDA Research, Inc with Department of Energy (DOE) funding is carrying out an investigation of the effects of coal and biomass contaminants on the performance (activity and selectivity) and life of the Water Gas Shift (WGS) and Fischer Tropsch (F-T) catalysts. The poisoning effects of heteroatoms (e.g., sulfur, nitrogen and oxygen) as well as halides and trace metals, are well-documented for these catalysts. In the co-gasification of coal and biomass, it is anticipated that ash, sulfur species, trace toxic metals, halides, and nitrogen species will be lower than in the synthesis gas generated by coal alone. Nevertheless, the impact of these contaminants must be re-evaluated at the reduced concentrations predicted for the intended application. In addition, the biomass feedstock will introduce a different spectrum of contaminants, including the vapors of alkali metals (such as sodium and potassium compounds) and their respective salts (e.g., KCl and NaCl), ammonia and phosphorous that could render the WGS and FT catalysts inactive.

We have first used thermodynamic modeling tools to identify contaminants that are most likely to react with the active phase and promoters used in the WGS and F-T catalysts. We then carried out screening experiments utilizing generic and commercial catalysts to measure changes in activity and selectivity due to exposure to contaminant species under representative conditions. In this paper, we will present the preliminary results from the catalyst development and contaminant evaluations done at TDA.