Implications of Precious Metal Catalysts with Leaded Fuels

The potential for catalysts, to operate with leaded fuel, was evaluated by screening catalysts under a variety of steady state and cyclic conditions with 0.4 g/l leaded fuel. The influence of precious metal loading, formulation and the level of inlet O₂ was also evaluated.

Pure Pt was superior to catalysts containing Pt and Pd. Cyclic aging provided much better catalyst performance retention than steady state exposure. The scavenging effect of HCl and HBr, which accomplishes deposit removal in the combustion chamber, may also operate on the catalyst where cyclic operation assures a proper balance of temperature above and below 550° C.