Catalyst Evaluation on a Detroit Diesel Allison 6V-92TA Methanol-Fueled Engine

The fresh catalytic activities of both a production Pt-Pd catalyst and a GMR Pd-promoted Ag catalyst were evaluated in back-to-back emissions tests on an experimental Detroit Diesel Allison (DDA) 6V-92TA methanol-fueled engine. Both the 13-mode steady-state and transient heavy-duty diesel engine Federal Test Procedures were employed. The production catalyst was characterized by relatively high conversions (70-90%) of unburned methanol and carbon monoxide in both the transient and 13-mode tests. However, the production catalyst promoted the partial oxidation of unburned methanol to formaldehyde, as indicated by large negative apparent conversions of formaldehyde in both the transient and steady-state tests (-77% transient; -188% 13-mode). In contrast, the Pd-promoted Ag catalyst converted formaldehyde with good efficiency (-90% in the 13-mode test and -50% in the hot transient test) but was much less efficient than the production catalyst for converting unburned methanol and carbon monoxide.