Cu SSZ-13 zeolite catalyst on metallic foam support for SCR of NOx with ammonia: Catalyst layering and characterisation of active sites

Abstract

A particular aim of this work was to develop a method of catalyst layering on the surface of metallic catalyst carriers used in structured reactors. The CuSSZ-13 catalyst was chosen as a prospective catalyst for SCR of NOx converter for exhaust from biogas engines. For the first time in the literature the method of in situ synthesis CuSSZ-13 catalyst was elaborated and tested for precalcined Kanthal foam. The CuSSZ-13 catalyst prepared in such a way demonstrated very high activity in NH3-SCR of NO with ammonia and high hydrothermal stability in comparison with analogically prepared CuZSM-5 used as a reference catalyst. The active centres working during SCR at various temperatures were investigated by in situ FTIR experiments with NH3 and CO probe molecules. The structure-activity relationships found for catalyst working at high temperature show that the Lewis acidic Cu+ sites are available exclusively for NO and Brønsted acidic sites for NH3 sorption above 400°C. Furthermore, high hydrothermal stability of the CuSSZ-13 catalyst is correlated to the favourable location of Al atoms in the zeolite lattice which prevents dealumination and also to the resulted from this stabilization of copper Cu+ active sites.