Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

Abstract

dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: the role of the interface periphery, Applied Catalysis B, Environmental http://dx.doi.org/10. 1016/j.apcatb.2015.07.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The catalytic tests in deN 2 O reaction revealed that the 10 wt.% of cobalt spinel in supported system is able to reproduce the activity of bare Co 3 O 4 catalyst. However, it was found that the catalyst with the lowest content of Co 3 O 4 equal to 1 wt.% exhibits the highest apparent reaction rate per mass of the spinel active phase. The observed activity was explained basing on the transmission electron microscopy analysis in terms of the dispersion of spinel phase over ceria support. A simple model that accounts for the observed strong dispersion effect is proposed. It consists in a two-step mechanism, where N 2 O is dissociated on the spinel nanograins and the resultant oxygen species are preferentially recombined at the Co 3 O 4 /CeO 2 interface periphery.

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

“…The obtained sample was dried at 120°C for 1 h, and then calcined at 500°C for 4 h. The catalyst was next doped with alkali (K or Cs) by incipient wetness impregnation with an aqueous solution of K 2 CO 3 (POCH, pure p.a.) or Cs 2 CO 3 (Aldrich) with concentrations corresponding to the surface loadings of potassium and cesium in the range of 0-10 atoms K/nm 2 and 0-6 atoms Cs/nm 2 [4,8,11,12]. Then, the cycle of drying and calcination was repeated.…”

“…Some of the most efficient catalysts for N 2 O abatement are based on cobalt spinel [3,4]. The catalytic performance of Co 3 O 4 can be modified by bulk doping with transition metal cations (such as Zn, Ni, Cu, Mn, Fe) [5][6][7][8][9][10] and surface doping with alkali dopants (Na, K, Cs) [3,8,[11][12][13].…”

“…However, despite such promising performance in the N 2 O decomposition reaction, the development of an industrial scale catalyst based on Co 3 O 4 as a bulk active phase was hindered by the unsatisfactory mechanical stability of the catalyst extrudates and by the high price of cobalt as well. These problems can be solved quite readily by the dispersion of cobalt spinel active phase on a shaped support such as alumina, silica, magnesia or ceria [4,[18][19][20][21][22]. However, since the alkali promoter loading is crucial for the deN 2 O performance of the catalyst, and both the under-and the over-doping lead to pronounced deterioration of the activity, the alkali promotion level must be carefully adjusted for a given catalyst.…”

N2O Direct Dissociation over MgxCeyCo1−x−yCo2O4 Composite Spinel Metal Oxide

“…Commonly, there are three ways for N 2 O abatement, including thermal pyrolysis [6], selective catalytic reduction [7][8][9], and direct decomposition [10][11][12][13][14][15][16][17]. The advantage of thermal pyrolysis is that it does not need catalyst.…”

“…Meanwhile, ceria (CeO 2 ), which is commonly used as a catalytic support, possesses good oxygen storage capacity and thermal stability, which can also effectively enhance the deN 2 O catalytic activity of Co 3 O 4 [14]. Therefore, in the present work, a series of single Mg-or Ce-doped Co 3 O 4 (Mg x Co 1−x Co 2 O 4 or Ce x Co 1−x Co 2 O 4 , respectively) and Mg, Ce co-doped Co 3 O 4 (Mg x Ce y Co 1−x−y Co 2 O 4 ) spinel composite metal-oxide catalyst were prepared by a coprecipitation method, which was further evaluated for N 2 O direct decomposition.…”