Ultrahighly Alkali-Tolerant NO x Reduction over Self-Adaptive CePO 4 /FePO 4 Catalysts.

Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NO x with NH 3 (NH 3 -SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % K 2 O difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH 3 -SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % K 2 O tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO 4 bulk phase. Amorphous FePO 4 as a support of the NH 3 -SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO 4 and were anchored by PO 4 3- with the generation of Fe 2 O 3 at the NH 3 -SCR reaction temperature. This ingenious potassium storage mechanism could boost the K 2 O resistance capacity to 6 wt % while maintaining approximately 81% NO x conversion. Besides, amorphous FePO 4 also exhibited excellent resistance to individual and coexistence of alkali (K 2 O and Na 2 O), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO 4 /FePO 4 catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO 4 paves the way for the development and implementation of poisoning-resistant NO x abatement.