Search

Highlights: [•] Presence of bulk WO3 on titania surface leads to deficiency of Brønsted acid sites. [•] Two-dimension VO x has a tendency to anchor onto titania surface in vicinity of WO x . [•] WO x shows compressing effects on monolayer VO x species at high vanadium loadings. [•] NH3-SCR performance is mainly dependent on vanadium contents of V W/TiO2 catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • AgCo-g-CN possessed enhanced catalytic decomposition of N 2 O under O 2 compared with Co 3 O 4. • Metallic Ag and higher content of Co2+ were found on AgCo-g-CN by adding g-CN. • Higher contents of Co2+ could play a beneficial role in the enhancement of N 2 O catalytic decomposition. • Metallic Ag improved the O 2 desorption capacity of AgCo-g-CN. Nitrous oxide (N 2 O) has gained increasing attention as an important greenhouse gas and stratospheric-ozone-depleting substance. Catalytic decomposition is considered an effective method for N 2 O abatement. Herein, AgCo-g-CN catalyst prepared by impregnation synthetic procedure was tested for N 2 O catalytic decomposition in the presence of O 2. The catalytic results indicated that full N 2 O conversion was obtained at 400 °C. The enhancement of catalytic activity was mainly derived from the addition of g-CN compared with bare Co 3 O 4 and AgCo. Metallic Ag and higher content of Co2+ were found over the AgCo-g-CN catalyst. By XPS and kinetic analysis, the catalytic performance was correlated with the content of Co2+, the facilitation of Co2+ contents could play a beneficial role in the enhancement of the AgCo-g-CN catalysts. Besides, HRTEM, XPS, and TPx revealed that metallic Ag improved the O 2 desorption capacity of AgCo-g-CN, which is important during the N 2 O catalytic decomposition. By lowering the valence of Co and Ag species, g-CN enhanced the catalytic performance of N 2 O. This study might provide a reference for designing N 2 O decomposition catalysts and potential applications for g-CN in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Different Fe/SAPO-34 catalysts were prepared by a solid-state ion exchange method and used to catalyze N 2 O decomposition. The catalytic performance of these catalysts was strongly related to their Fe precursors. Relevant characterization was carried out using X-ray diffraction, N 2 adsorption-desorption, UV–vis spectroscopy, electron paramagnetic resonance, and H 2 temperature-programmed reduction. The data indicated that the nature and distribution of Fe species in the catalysts changed with different Fe precursors used. Furthermore, monomeric Fe3+ ions and small oligomeric Fe x O y were the active Fe species for the Fe/SAPO-34 catalysts. Finally, it is reasonable to speculate that such a Fe source effect could be explored for other reactions. Unlabelled Image • N 2 O decomposition over Fe/SAPO-34 using different Fe precursors was first investigated. • The distribution of Fe species in the catalysts changed with different Fe precursors used. • Monomeric Fe3+ ions and small oligomeric Fe x O y were the active Fe species. [ABSTRACT FROM AUTHOR]

Pt-Au/TiO 2 -CeO 2 catalyst for the co-oxidation of HCHO, H 2 and CO at 25 °C. • The Pt-Au/TiO 2 -CeO 2 catalyst exhibited high catalytic activity for the co-oxidation of HCHO, H 2 and CO at room temperature. • CO restrained the oxidation of HCHO and H2 due to the CO self-poisoning effect. • H2 promoted the oxidation of HCHO and CO because of the generation of OOH and OH active species. • The deactivation was due to chemical state changes of active site and the accumulation of carbonates-like species. The deactivation origins of the Pt-Au/TiO 2 -CeO 2 catalyst for co-oxidation of formaldehyde (HCHO), hydrogen (H 2) and carbon monoxide (CO) at room temperature were studied by means of XRD, BET, H 2 -TPR, O 2 -TPD, XPS and in-situ DRIFTS. The results suggested that the catalyst deactivation was mainly caused by the reduction of Au+ species, the decrease of Ce3+ species and interaction weakness between active components and support. Moreover, during the co-oxidation process, CO showed a negative influence on the oxidation of HCHO and H 2 due to the CO self-poisoning effect, whereas H 2 promoted the oxidation of HCHO and CO because of the generation of OOH and OH active intermediates from the H 2 oxidation. Meanwhile, the accumulations of carbonate-like species as well as the production of H 2 O on the deactivated catalyst were also observed, accounting for the complete catalyst deactivation. [ABSTRACT FROM AUTHOR]