Phosphotungstic acid supported on Fe2O3 nanorods: synergistic active sites boosting NH3-SCR performance and SO2/H2O tolerance

HPW/Fe 2 O 3 nanorod catalyst displays excellent NH 3 -SCR performance over a broad working window. • HPW/Fe 2 O 3 exhibits higher SO 2 and H 2 O resistance compared with bare Fe 2 O 3 nanorods. • The modification of Fe 2 O 3 with HPW enriches the surface reactive oxygen species and acid sites of catalyst. • The NH 3 -SCR reaction on HPW/Fe 2 O 3 obeys the L-H and E-R routes simultaneously. Exploiting denitration catalysts that integrate exceptional low-and-medium temperature catalytic activity with superior SO 2 and H 2 O tolerance remains a core bottleneck for practical NO x abatement in industrial flue gas treatment. Here, a novel HPW/Fe 2 O 3 nanorod catalyst with highly exposed (110) facet modified by phosphotungstic acid was successfully synthesized. Compared with pure Fe 2 O 3 nanorods, the HPW/Fe 2 O 3 catalyst with a 15% phosphotungstic acid loading exhibited the most outstanding catalytic performance, delivering nearly 100% NO x conversion and N 2 selectivity within the temperature window of 250–425 °C. The characterization results revealed that the interaction between HPW and Fe 2 O 3 generated more oxygen vacancies, which significantly enhanced the low-temperature NO x conversion of HPW/Fe 2 O 3 . Meanwhile, the abundant moderately strong acid sites inhibited the over-oxidation of NH 3 at high temperatures, thereby improving the high-temperature NO x conversion of HPW/Fe 2 O 3 . The introduction of HPW significantly suppressed SO 2 adsorption on the HPW/Fe 2 O 3 surface, endowing the catalyst with favorable tolerance toward the coexistence of H 2 O and SO 2 at 250 °C. Time-resolved in-situ transient measurements and kinetic analyses disclosed that the adsorbed NH 3 species on the HPW/Fe 2 O 3 surface were capable of reducing gaseous/adsorbed NO x simultaneously, following both the Eley-Rideal ( E -R) and Langmuir-Hinshelwood (L-H) routes. The phosphotungstic acid-modified HPW/Fe 2 O 3 catalyst is endowed with abundant active oxygen species and moderately strong acid sites, which greatly facilitates the NH 3 -SCR reaction proceeding via both the Eley-Rideal ( E -R) and Langmuir-Hinshelwood (L-H) pathways. Download: Download high-res image (160KB) Download: Download full-size image