Optimization of cesium and potassium promoter loading in alkali-doped Zn0.4Co2.6O4|Al2O3 catalysts for N2O abatement

Abstract

A series of potassium or cesium doped Zn 0.4 Co 2.6 O 4 |Al 2 O 3 catalysts with different alkali loadings were prepared, characterized with respect to chemical composition (XRF), structure (XRD, RS) morphology (TEM), and the alkali promoter thermal stability. A strong beneficial effect on the deN 2 O activity of the Zn 0.4 Co 2.6 O 4 |Al 2 O 3 catalyst (decrease in the T 50% by about 80°C) was observed for both promoters at different surface coverages. It was found that in comparison to a rather narrow range of optimal cesium loading (0.5-2 atoms/nm 2 ) a comparable promotional effect of potassium doping was observed for a slightly wider surface concentrations (0.5-3 atoms/nm 2 ). Such difference was attributed to surface dispersion of potassium over the alumina support and the spinel active phase, while cesium was found to be located mainly on the spinel phase. For practical applications, the superiority of potassium over cesium consist in fact that a similar beneficial effect is associated with much higher thermal stability in the temperature range of the catalyst deN 2 O operation and lower price of the promoter precursor.

Influence of co-fed gases (O2, CO2, CH4, and H2O) on the N2O decomposition over (Co, Fe)-ZSM-5 and (Co, Fe)-BETA catalysts

“…Results of the reaction rate calculation at 450 °C also showed that Co-BETA (14.2 h −1 ) and Co-ZSM-5 (12.0 h −1 ) were more effective catalysts than Fe-BETA (1.9 h −1 ) and Fe-ZSM-5 (3.0 h −1 ). In addition, the reaction rates of our cobalt-zeolite catalysts were much higher than those of cobalt oxides (≤ 1 h −1 ) [39][40][41] [23]. Therefore, the activity of our Fe-BETA and Fe-ZSM-5 catalysts is within the range of reaction rates found in the literature.…”

Effect of Potassium Doping on the Structural and Catalytic Properties of Co/MnOx Catalyst in the Steam Reforming of Ethanol

“…00-075-1090) (Figure 4C,D). In addition to the predominant diffraction peaks derived from the MnO support, weaker diffraction lines at 2θ = 43.7 • and 51.2 • , corresponding to the reflection planes of the Co 0 phase, are visible [16,[21][22][23][24][25][26][27][28]. Moreover, the absence of any potassium phase for the KCo/MnO x catalyst in the XRD patterns may result from several factors, namely its considerably low amount and/or amorphous form and/or high dispersion over the catalyst surface [16,29].…”

CO-PROX Reaction over Co3O4|Al2O3 Catalysts—Impact of the Spinel Active Phase Faceting on the Catalytic Performance

“…In order to resolved those discrepancies and to establish the most active termination of cobalt spinel in a definite way, we have examined the CO-PROX process on a uniform type of Co 3 O 4 catalyst supported on alumina, where the polyhedral shape of the spinel nanoparticles was tailored by glycerol addition to the impregnation solution and/or by non-redox Zn-dopin. 35 This allows for controlled variation of the (100), (111) and (110) faceting, while preserving the overall polyhedral shape and size of the spinel active phase nanocrystals. It is worth emphasizing that, in contrast to previous literature, the catalysts used in these investigations are not model single nanocrystals but real supported catalysts applicable on a large scale.…”