(88a) Catalytic Formation of Carbonyl Sulfide During Treatment of Coal-Derived Fuel Gas with Pd/γ-Al2O3 Sorbents

This group has developed a Pd/γ-Al₂O₃ sorbent capable of removing trace contaminants at moderate to high temperatures (200 – 450 °C) from coal-derived fuel gas. In the development of the sorbent, the catalytic formation of carbonyl sulfide (COS) was noted, which would require modification to sulfur removal processes. The formation of COS over a Pd catalyst is also a major concern for Pd alloy based hydrogen separation membranes proposed for use with fuel gas. The conditions required for catalytic formation have been explored, with up to 80 ppmv COS formed under gas-solid contact times of under 0.1 s. A reaction mechanism is proposed and multiple kinetic models are explored based on experimental results. The potential for hydrolysis of COS based on the γ-Al₂O₃ support is considered.