Alkali and Heavy Metal Copoisoning Resistant Catalytic Reductionof NOxvia Liberating Lewis Acid Sites

The catalyst deactivation caused by the coexistence of alkali andheavy metals remains an obstacle for selective catalytic reduction of NOxwith NH3.Moreover, the copoisoning mechanism of alkali and heavy metals is still unclear.Herein, the copoisoning mechanism of K and Cd was revealed from the adsorptionand variation of reaction intermediates at a molecular level through time-resolvedinsituspectroscopy combined with theoretical calculations. The alkali metal K mainlydecreased the adsorption of NH3on Lewis acid sites and altered the reaction moredepending on the formation of the NH4NO3intermediate, which is highly related toNOxadsorption and activation. However, Cd further inhibited the generation ofactive nitrate intermediates and thus decreased the NOxabatement about 60% onpotassium-poisoned CeTiOxcatalysts. Physically mixing with acid additives forCeTiOxcatalysts could significantly liberate the active Lewis acid sites from theoccupation of alkali metals and relieve the high dependence on NOxadsorption andactivation, thus recovering the NOxremoval rate to the initial state. This work revealed the copoisoning mechanism of K and Cd onCe-based de-NOxcatalysts and developed a facile anti-poisoning strategy, which paves a way for the development of durable catalystsamong alkali and heavy metal copoisoning resistant catalytic reduction of NOx

Automated summary

This study reveals the poisoning mechanism of alkali and heavy metals on Ce-based de-NOx catalysts and develops an effective anti-poisoning strategy. It provides new insights for the development of sustainable catalysts resistant to alkali and heavy metal co-poisoning.