Metal-exchanged Zeolites for SCR Catalysts

This lecture covers the use of metal-exchanged zeolites as selective catalytic reduction (SCR) catalysts for diesel emission control. It discusses the general formula of zeolites, the substitution of silicon atoms by metal cations, and the compensation of excess negative charge. Different zeolite structures like BEA, MFI, and CHA are explained, along with the location of exchanged metal atoms. The lecture also delves into the SCR reaction rate dependency on NO concentration, ammonium nitrate formation, and the comparison of NO-SCR over different catalysts. It explores the sulfur sensitivity of Fe-zeolites and Cu-SPZ, the preparation of iron-exchanged zeolites, and the correlation of activity measurements with different iron species. The optimization of Fe-ZSM-5 SCR catalysts by maximizing isolated species concentration is also discussed.