Selective catalytic reduction of nitric oxide by hydrocarbons

There are several problems related to the application of currently available NOx control technologies (i.e. three-way catalysts and the selective catalytic reduction of NO by NH,) to lean burn diesel engines, and thus a very significant market potential exists for an improved technology in this area. As a result, the selective catalytic reduction of NO by hydrocarbons derived from on board fuel has received a lot of attention in the past five years. Different forms of base and noble metal exchanged zeolites, as well as supported noble metals appear to be the most active catalysts for this family of reactions. The available literature in this area is summarized in this review, with emphasis placed on the performance of different zeolite and supported noble metal catalysts, the effect of the various exhaust gas components and the mechanistic implications.