Laboratory scale studies of Pd/γ-Al2O3 sorbents for the removal of trace contaminants from coal-derived fuel gas at elevated temperatures

The Integrated Gasification Combined Cycle (IGCC) is a promising technology for the use of coal in a clean and efficient manner. In order to maintain the overall efficiency of the IGCC process, it is necessary to clean the fuel gas of contaminants (sulfur, trace compounds) at warm (150-540 °C) to hot (>540 °C) temperatures. Current technologies for trace contaminant (such as mercury) removal, primarily activated carbon based sorbents, begin to lose effectiveness above 100 °C, creating the need to develop sorbents effective at elevated temperatures. As trace elements are of particular environmental concern, previous work by this group has focused on the development of a Pd/γ-Al2O3 sorbent for Hg removal. This paper extends the research to Se (as hydrogen selenide, H2Se), As (as arsine, AsH3), and P (as phosphine, PH3) which thermodynamic studies indicate are present as gaseous species under gasification conditions. Experiments performed under ambient conditions in He on 20 wt.% Pd/γ-Al2O3 indicate the sorbent can remove the target contaminants. Further work is performed using a 5 wt.% Pd/γ-Al2O3 sorbent in a simulated fuel gas (H2, CO, CO2, N2 and H2S) in both single and multiple contaminant atmospheres to gauge sorbent performance characteristics. The impact of H2O, Hg and temperature on sorbent performance is explored.