Promotion mechanism of CeO₂addition on the low temperature SCR reaction over MnO_x/TiO₂: a new insight from the kinetic study

Abstract

A new insight into CeO2 addition on the SCR reaction over MnOx/TiO2 was drawn according to steady-state kinetic analysis.

Influence of the Preparation Method of Ag-K/CeO2-ZrO2-Al2O3 Catalysts on Their Structure and Activity for the Simultaneous Removal of Soot and NOx

“…CVI70 does show a reduction in the concentration of NOx and NH3, but this does not occur simultaneously, this is partially due to NH3 storage by the support, probably on Lewis acid sites (oxygen vacancies) on the CZA. The adsorbed NH3 species can subsequently take part in the SCR reaction via a Langmuir-Hinshelwood mechanism [26]. N2O begins to form at 275 °C but is not used CVI70 does show a reduction in the concentration of NOx and NH 3, but this does not occur simultaneously, this is partially due to NH 3 storage by the support, probably on Lewis acid sites (oxygen vacancies) on the CZA.…”

“…N2O begins to form at 275 °C but is not used CVI70 does show a reduction in the concentration of NOx and NH 3, but this does not occur simultaneously, this is partially due to NH 3 storage by the support, probably on Lewis acid sites (oxygen vacancies) on the CZA. The adsorbed NH 3 species can subsequently take part in the SCR reaction via a Langmuir-Hinshelwood mechanism [26]. N 2 O begins to form at 275 • C but is not used to oxidize soot, as the same quantity of N 2 O was formed in the absence of soot (see supplementary information, Figure S1).…”

The catalytic performances and reaction mechanism of nanoparticle Cd/Ce–Ti oxide catalysts for NH3-SCR reaction

“…It was noticeable that the bands assigned to NO x species (1606 and 1579 cm À1 ) are absent and only two bands related to NO 2 appear, indicating that the adsorption of nitrate species is inhibited. [26][27][28][29][30][31][32] (4) Reaction between ammonia and adsorbed nitrogen oxides species. Fig.…”

“…With the temperature increasing, the intensity of the bands assigned to NH 4 + species on Brønsted acid sites (1442, 1674 cm À1 ) decrease faster than that of the bands ascribed to coordinated NH 3 on Lewis acid sites (3363, 3264, 3168 and 1596 cm À1 ). [26][27][28][29][30][31][32] The adsorbed NH 3 species on Brønsted acid site disappeared completely at 200 C, while the band at 1203 cm À1 attributed to the symmetric bending vibrations of N-H bond in NH 3 coordinately linked to Lewis acid site is also detected even at 350 C. In situ DRIFTS spectra over Cd 2 /Ce 0.3 -TiO x catalyst show that there is the adsorbed NH 3 species on both Lewis and Brønsted acid site, and the absorbed nitrate and nitrite species form on the surface of catalyst at room temperature. While when the temperature exceeds 150 C, all bands attributed to NO x and NH 3 species vanish gradually except the bands attributed to adsorbed NH 3 species on Lewis acid site.…”

“…Thus the in situ DRIFTS spectra of Cd 2 /Ce 0.3 -TiO x catalyst show that, the main L-H mechanism may gradually transform to E-R-oriented mechanism with the increasing of the temperature. [26][27][28][29][30][31][32]…”