Unexpected offsetting effect of Na and HCl deactivation over CeO2-MoO3 catalyst for NO reduction

Abstract

This work mainly illustrated the synergistic effects of Na and HCl on the SCR performance of CeMo catalysts. Given that the fresh CeMo catalyst was treated with HCl or doped by Na, the weakened acidity and oxidizability would interfere with the adsorption and activation of NH3, thus resulting in a downward trend of the catalyst deNOx performance. Notably, for the HCl treated Na-poisoned catalyst, the treatment with HCl introduced additional acid sites onto the Na-poisoned catalyst surface and increased the availability of Ce4+ and chemisorbed oxygen. These behaviors exerted a certain promotional effect on the adsorption and activation of NH3. Apparently, the catalyst's deNOx performance slightly rebounded, suggesting the offsetting effects of HCl. Such knowledge would be vital to the stable operation in real coal-fired flue gas.