Effect of hydrothermal aging on the proton distribution in Cu-CHA zeolite catalysts

Cu-CHA zeolites are excellent catalysts for the removal of NOx from diesel vehicle exhaust gases, through the NH3-SCR reaction. Even if they are outperforming other Cu-zeolites for their activity and hydrothermal stability, the harsh conditions of temperature and presence of water vapour in the exhaust can cause the phenomenon called dealumination, which removes Al atoms from the framework and causes deactivation. We want to study the effect of hydrothermal ageing on the distribution of OH groups in Cu-CHA by means of Inelastic Neutron Scattering on the high resolution instrument TOSCA, to understand the main parameters affecting stability.