Functionalized Iron Hydroxyapatite as Eco‐friendly Catalyst for NH 3 ‐SCR Reaction: Activity and Role of Iron Speciation on the Surface

CAMPISI, SEBASTIANO; AUROUX, ALINE; GALLONI, MELISSA G.; POSTOLE, GEORGETA; MARCHETTI, SERGIO G.; GERVASINI, ANTONELLA

CHEMCATCHEM

WILEY-V C H VERLAG GMBH

Año: 2020 vol. 12 p. 1676 - 1690

1867-3880

Eco-friendly catalysts have been obtained by functionalizinghydroxyapatite (HAP) with iron (Fe/HAP), according to threepreparative methods (flash ionic exchange, deposition-precipitation,and impregnation). Fe/HAP samples (ca. 2?7 wt.% Fe)have been tested in the reaction of NOx reduction by ammonia(NH3-SCR) in the 120?500 °C interval with different NH3/NOratios (0.6?2) at fixed contact time (0.12 s). All Fe/HAP sampleswere active and selective in the NH3-SCR reaction starting fromca. 350 °C. Better performances have been observed on catalystsprepared by deposition-precipitation and impregnation (about70 %ofNOxconversion and selectivity to N2 higher than 95 %at350 °C), where α-Fe2O3 and 3D-Fe2O3 nanoclusters were present,as indicated by Mössbauer and UV-Vis-DR spectroscopies. Onthe opposite, paramagnetic Fecentres were the predominantspecies on samples prepared by flash ionic exchange. Furthercharacterization techniques (XRPD, N2-physisorption, acidity byNH3 adsorption, and H2-TPR) have concurred to elucidate FesittingHAP and structure-activity relationships.3+