Mechanistic studies of catalytic NOx reduction with added oxygenates

The reduction of NOx in diesel exhaust is an important societal and scientific problem. The chemistry for NOx reduction can be quite complex, and delineating a detailed microscopic mechanism is challenging. However, to implement catalytic NOx remediation an understanding of the mechanism for NOx reduction is critical. We have investigated the mechanism for NOx reduction involving ammonia, acetaldehyde, ethanol, and nitromethane as added reductants over zeolites and/or metal oxide catalysts. These mechanisms will be presented with an emphasis on the common critical reaction steps. Our work has also demonstrated that NO can reduce nitric acid, ammonium nitrate, and surface nitrates to nitrous acid and the corresponding nitrites.