Selective Reduction of Nitrogen Oxides (NOx) with Oxygenates and Hydrocarbons over Bifunctional Silver-Alumina Catalysts: a Review

The design of silver-alumina catalysts for the selective reduction of nitrogen oxides (NOx) by organic compounds (oxygenates and hydrocarbons) is reviewed. Possible mechanisms for the selective reduction of NOx and the nature of the active sites are analyzed. The role of the components of the Ag/Al2O3 composition to the selective catalytic reduction (SCR) activity are discussed. Comparison of the results obtained on different silver-alumina catalysts indicates promise for the use of structured Ag/Al2O3/cordierite systems, which provide for the almost complete conversion of NO selectively to molecular nitrogen at 300-400 A degrees C.