Selective catalytic reduction of NO with NH3 over iron titanate catalyst: Catalytic performance and characterization

Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

“…Compared with the FeTiO x catalyst prepared using TiCl 4 as a precursor and a Fe 2 O 3 /TiO 2 catalyst prepared by an impregnation method, the existence of sulfate species in the preparation process could significantly inhibit the crystallization of mixed metal oxide phases, resulting in the formation of highly dispersed small iron titanate crystallites, which is totally different from the Fe 2 O 3 particles normally found in previously reported studies. 52 A similar promotion effect by sulfate species on the dispersion of Fe species was also observed by Ma et al on their Fe 2 (SO 4 ) 3 / TiO 2 catalyst. 50 Thereafter, the microstructure of iron titanate crystallites in FeTiO x catalysts was studied in detail using various characterization methods, including N 2 physisorption, Powder XRD, UV-vis DRS, Raman spectroscopy and XAFS etc., and the surface chemical composition and redox behavior were studied using XPS and H 2 -TPR.…”

Effect of manganese substitution on the structure and activity of iron titanate catalyst for the selective catalytic reduction of NO with NH3

“…For each sample, two characteristic peaks attributed to Ti 2p 3/2 at 458.6 eV and Ti 2p 1/2 at 464.4 eV showed up, indicating the presence of Ti 4+ [50]. As the XPS results shown in our previous study [6], the binding energies of Ti 2p 3/2 and Ti 2p 1/2 in FeTiO x were smaller than those in pristine TiO 2 due to the strong interaction between iron and titanium species. This phenomenon was probably caused by the deviation of electronic cloud from Fe 3+ to Ti 4+ , because Ti 4+ shows stronger affinity of electrons comparing with that of Fe 3+ .…”

“…Two characteristic peaks ascribed to Fe 2p 3/2 at 711.4 eV and Fe 2p 1/2 at 724.9 eV appeared for each Fe-containing sample, indicating that the iron species in these samples was in Fe 3+ oxidation state [46]. It was reported in our previous study that the iron species in iron titanate catalyst possessed higher binding energies than that in pristine Fe 2 O 3 due to the strong interaction between iron and titanium species [6], and the substitution of partial Fe by Mn did not change this situation. The iron species with enhanced oxidative ability than that in Fe 2 O 3 was still responsible for the high SCR activity.…”

“…The interaction between iron, manganese and titanium species led to a highly dispersive state of active phases, without forming iron oxides, manganese oxides or titanium oxide particles. In our previous study [5,6], we have concluded that the FeTiO x catalyst was mainly in the form of crystallite phases of Fe 2 TiO 5 and FeTiO 3 with specific Fe-O-Ti structure which showed high SCR activity. The substitution of Fe by Mn did not destroy the crystallite structures; furthermore, some crystallites with Mn-O-Ti and Fe-O-Mn structures might also be formed, because either FeMnTiO 4 or MnTiO 3 also has some diffraction peaks in the positions of the broad bumps.…”

“…Because of some inevitable disadvantages in practical application, such as the narrow operation temperature window [2], high conversion of SO 2 to SO 3 at high temperatures [3] and the toxicity of vanadium pentoxide to environment and human health [4], more and more researchers are focusing on the development of new SCR catalysts. In our previous study [5,6], we have developed an environmentally friendly novel iron titanate catalyst in crystallite phase with specific Fe-O-Ti structure, which showed excellent SCR activity, N 2 selectivity and H 2 O/SO 2 durability in the medium temperature range. However, the catalytic activity was not high enough for the application in denitrogenation of exhaust gas with low temperature, such as the flue gas after dust removal and desulfurization from coal-fired power plants and the exhaust gas from diesel engines in cold-start process.…”