The role of various iron species in Fe-β catalysts with low iron loadings for NH₃-SCR

Abstract

A series of Fe-β catalysts, containing 0.17–0.52 wt% Fe, were prepared by a liquid ion-exchange method to study the influence of various iron species on NH3-SCR activity.

Alumina as Solid‐State Ligand in Enhancing the Redox Catalytic Property of Iron Oxide Grafted AlSBA‐15 towards Arylation of Arene

“…Irrespective of the iron loading (2, 4, 8 wt %) and kind of support (SBA‐15, AlSBA‐15), each one of the samples contains a peak, intense band and shoulder at about 250 nm, 320 nm and 470 nm, respectively. It confirms the presence of isolated Fe III in octahedral environment (270 nm), Fe III ‐clusters (320 nm) and amorphous FeO x oligomers (470 nm) ,. The non‐appearance of peaks above 500 nm indicates the absence of bulk iron oxide particles in all the samples, which is in good agreement with the wide angle XRD results.…”

“…It confirms the presence of isolated Fe III in octahedral environment (270 nm), Fe III -clusters (320 nm) and amorphous FeO x oligomers (470 nm). [7,[17][18][19][20] The non-appearance of peaks above 500 nm indicates the absence of bulk iron oxide particles in all the samples, which is in good agreement with the wide angle XRD results. The similar DRS-UV patterns of 2, 4, 8wt%Fe/SBA-15 and 2, 4, 8 wt %Fe/AlSBA-15 rises ambiguity on (i) effect of alumina in controlling the dispersion of various oxide iron species (ii) whether iron has been grafted over alumina and/or remaining silanols.…”

A Sustainable Heterogeneous Iron Catalyst Fe/SBA‐15 towards Direct Arylation of Unactivated C(sp3)−H and C(sp2)−H Bonds with Arenes

“…The extra framework iron present in zeolite structure, similar to grafted isolated Fe III , in octahedral and distorted octahedral environment signals at g value slightly lesser than 2 and for fully rhombic environment at 4.3. However, the signal slightly lesser than 2 may also indicate the presence of iron oxide clusters . The absence of signals at g =2.2–2.5 evidences devoid of iron oxide in the mesopores of silica .…”

“…DRS‐UV spectrum of 8 wt %Fe/SBA‐15 (Supporting Information, Figure S5) showed a weak signal at 220 nm and a peak at 250 nm due to oxygen to Fe III charge transfer involving isolated Fe III in octahedral environment . Furthermore, an intense band at 330 nm and a shoulder at 470 nm at higher wavelength can be assigned to Fe III ‐clusters and amorphous FeO x oligomers, respectively, due to increase in the nuclearity of Fe III oxide ,,. The absence of peak beyond 500 nm undoubtedly indicates the absence of bulk iron oxide phase formation in the mesopores during the grafting process …”

Highly dispersed Fe2O3 on carbon nanotubes for low-temperature selective catalytic reduction of NO with NH3

“…However, the NO conversion at low temperatures (<250°C) had not evidently improved yet. Liu et al 17 found that Fe-β catalysts showed less than 70% NO conversion below 250°C. Yang et al 18 studied that V 2 O 5 /Fe 2 O 3 -TiO 2 catalysts revealed less than 80% NO conversion below 250°C.…”