Catalytic Removal of NOX Species from Auto-exhaust and Power Plant Emissions

2 Catalytic Removal of NOx Species from Auto-exhaust and Power Plant Emissions 

It may be, however, that no single phase zeolite catalyst is able to fulfil the role, and there has also been interest in bifunctional lean burn-deNOx catalysts where the zeolite is mixed with another catalyst. A zeolitic catalyst may be used together with a supported Pt/Al203 catalyst that is more active for NOx reduction at low temperatures. Other examples include Mn203/Ce-ZSM-5, where the manganese oxide catalyses NO oxidation to NO2, which reacts rapidly over the metal-containing zeolite, and Pt/H-ZSM-5, where the acid sites activate the hydrocarbon and promote its reaction with the NOx- 

NOx abatement is also required at stationary power sources. In these situations, ammonia is used as a reductant to selectively reduce the NOx (and not the O2) in the gas stream. As well as precious metal catalysts, zeolitic catalysts are commercially available for this reaction. Examples of successful 

---