Hydrogen Sulfide Formation Over Automotive Oxidation Catalysts

Abstract

<div class="htmlview paragraph">A number of laboratory and engine dynamometer studies were conducted to determine the effect of various catalyst and engine operating parameters on the formation of H<sub>2</sub>S over alumina-supported Pt and Pd catalysts.</div> <div class="htmlview paragraph">These experiments indicate that H<sub>2</sub>S formation occurs at high temperatures under O<sub>2</sub> deficient conditions. The fraction of exhaust gas SO<sub>2</sub> converted to H<sub>2</sub>S was relatively constant for various fuel sulfur levels, and thus H<sub>2</sub>S formation decreases as fuel sulfur content decreases. Calculation of thermodynamic equilibria, as well as various experimental results, indicate that H<sub>2</sub>S formation is kinetically limited under the experimental conditions investigated.</div> <div class="htmlview paragraph">Since the operating conditions that favor H<sub>2</sub>S formation (high catalyst temperature and O<sub>2</sub> deficiency) do not normally occur in current oxidation catalytic emission control system operation, the formation of H<sub>2</sub>S over automotive oxidation catalysts is unlikely unless engine or system malfunctions occur.</div>