Search

A series of Sb-doped CeVO 4 samples were synthetized by hydrothermal method and used in selective catalytic reduction of NO with NH 3. Contrasted with other catalysts, Sb 2 CeVO 4 possessed superior NH 3 -SCR activity and excellent SO 2 tolerance. Besides, the characterization results testified that Sb species in Sb 2 CeVO 4 could reduce the crystallization of CeVO 4 , and improve the surface acidity and reducibility. Moreover, the existence of Sb3+ was beneficial to generate more surface adsorbed oxygen species. Based on the in situ DRIFT spectra, more ad-NH 3 and ad-NO x species with higher reactivity were obtainable on Sb 2 CeVO 4 catalyst compared with that on CeVO 4 catalyst, which also contributed to enhancing the SCR activity by Langmuir-Hinshelwood (L-H) mechanism effectively. Image 1 • Sb modification could improve the SCR performance of CeVO 4 catalyst. • Sb3+ was beneficial to generate more surface adsorbed oxygen species. • More active ad-NH 3 and ad-NO x species were available on Sb 2 CeVO 4 catalyst. [ABSTRACT FROM AUTHOR]

Some fly ash components such as K could seriously weaken the catalytic performance of SCR catalyst. In this study, the core-shell-structured MnFeOx@TiO 2 catalyst is synthesized by dipping deposition method and used for the NH 3 -SCR reaction. The results show that MnFeOx@TiO 2 catalyst exhibits higher K resistance than MnFeOx/TiO 2 catalyst prepared by impregnation method. And the correlativity between the core-shell morphology and K resistance of MnFeOx@TiO 2 catalyst is studied by TEM, N 2 adsorption, XRD, XPS, TPR, TPD and in situ DRIFT. It can be found that the shell of TiO 2 has a protective effect on the active species in MnFeOx@TiO 2 catalyst. And the core-shell structure of MnFeOx@TiO 2 catalyst can produce more Mn4+ and chemisorbed oxygen species on its surface, improving reducibility and surface acidity. Moreover, the core-shell structure of MnFeOx@TiO 2 catalyst is beneficial to the adsorption of NH 3 and the formation of NO 2 , resulting in the favored SCR reaction via the Eley−Rideal and the Langmuir−Hinshelwood routes. Therefore, MnFeOx@TiO 2 catalyst shows excellent K tolerance. Image 1 • The core-shell structure of MnFeOx@TiO 2 catalyst could protect the active species from the contact with K species. • The morphology of MnFeOx@TiO 2 catalyst is propitious to the conversion from to NO 2. • The SCR process over MnFeOx@TiO 2 catalyst was advanced via both E-R and L-H modes. [ABSTRACT FROM AUTHOR]

TiO 2 supported Ce Mo catalyst (Ce Mo/TiO 2) were employed for the first time to simultaneously oxidize elemental mercury (Hg0) and reduce nitrogen monoxide (NO) under simulated SCR atmosphere. The combination of molybdenum oxides and cerium oxides exhibits obvious synergy for Hg0 oxidation and NO reduction. Ce Mo/TiO 2 -0.3 catalyst exhibited an excellent Hg0 oxidation and NO reduction efficiencies of over 90% at above 250 °C corresponding to gas hourly space velocity (GHSV) of 119,000 h−1 (NO reduction) and 1,190,000 h−1 (Hg0 oxidation). Brunauer-Emmett-Teller (BET) surface area was not the dominating factor affecting the Ce Mo/TiO 2 performance. Well-dispersion of active species, abundant chemisorbed oxygen and large surface oxygen capacity were responsible for its high catalytic activity. The presence of Hg0 exhibited a negligible effect on NO reduction. Low-concentration of NO inhibited the Hg0 oxidation while a relatively high concentration had a promotional effect inversely due to abundant NO 2. NH 3 consumed surface oxygen and competed to adsorb with Hg0 resulting in the deactivation of Hg0 oxidation while an excellent recovery was observed after simultaneous cutting off NH 3 and introduction of O 2. In addition, Ce Mo/TiO 2 -0.3 catalyst also presented an excellent resistance to SO 2 and H 2 O poisoning and a good stability and recyclability. The possible mechanism for simultaneous NO reduction and Hg0 oxidation was proposed for Ce Mo/TiO 2 catalysts. The process of NO reduction and Hg0 oxidation over Ce-Mo/TiO2 catalyst. Image 1 • It is the first time that Ce Mo/TiO 2 catalyst was employed for the research of simultaneous Hg0 oxidation and NO reduction. • Low-concentration of NO inhibited the Hg0 oxidation while a relatively high concentration had a promotional effect. • The presence of Hg0 exhibited a negligible effect on NO reduction. • Ce Mo/TiO 2 -0.3 catalyst had an excellent recovery for NH 3 inhibition and resistance to SO 2 poisoning. [ABSTRACT FROM AUTHOR]

In present study, the poisoning mechanism of Cl on V/TiO 2 catalyst for SCR removal of NOx using NH 3 as the reductant was explored by in situ DRIFT technique. The experimental results revealed that the existence of Cl did not change the SCR reaction mechanism over V/TiO 2 catalyst, which was mainly under the control of both E-R and L-H mechanisms. The deactivation of V/TiO 2 catalyst by Cl was mainly resulted from the inhibited adsorption of NH 3 and NOx species, accompanied by the decrease of the reactivity of adsorbed NH 3 species. Image 1 • The addition of Cl on V/TiO 2 catalyst has an inhibition effect on the adsorption of NH 3 and NOx species. • The reactivity of adsorbed NH 3 species over V/TiO 2 catalyst would decrease after the loading of Cl. • The addition of Cl on V/TiO 2 catalyst does not change the mechanism of NH 3 -SCR reaction over it. [ABSTRACT FROM AUTHOR]