Selective Catalytic Reduction of Nitrogen Oxides by Hydrocarbons in an Excess of Oxygen

An analysis is performed of results from works performed with the active participation of V.V. Lunin on the selective catalytic reduction of nitrogen oxides by hydrocarbons in the presence of an excess of oxygen. The main characteristics of the mechanism of the reactions, which includes the key step of interaction between nitrite-nitrate complexes and hydrocarbons, are determined using a unique set of spectral and kinetic means. This forms the basis for designing active components of catalysts of these processes that ensure high surface coverages by nitrite-nitrate complexes under actual conditions of catalysis, high rates of hydrocarbon activation on such sites, and their effective interaction with the nitrite-nitrate complexes. This is achieved by changing the transition metal cation on the surface of the support, its nearest coordination environment, its degree of clustering, and the basicity of the support. This approach ensures high activity, selectivity, and stability in desirable reactions under actual conditions for active components based on cations of copper, cobalt, nickel, and iron, along with such supports as high-silica zeolites, partially stabilized zirconia, zirconia-pillared natural clays, and framework zirconium phosphates, including ones promoted with silver or platinum. For the practical use of these active components, procedures are developed to deposit them on cellular honeycomb substrates using binders, creating efficient catalysts protected by RF patents.