Co–Ce Oxides Supported on SBA-15 for VOCs Oxidation

Abstract

Reported here are new data on the structural and catalytic properties of a series of mono-component cobalt and bi-component Co–Ce catalysts supported on SBA-15 (Santa Barbara Amorphous-15)). The catalysts performance has been evaluated by tests on combustion of methane, propane, and n-hexane. It was established that the preparation of the Co–Ce catalysts by the ‘two-solvent’ technique does not significantly change the mesoporous structure, however, its pores are clogging with the Co and Ce guest species. Cobalt and cerium are uniformly distributed and preferentially fill up the channels of SBA-15, but oxide agglomerates located on the surface are observed as well. The highest activity of the mono-component cobalt sample is explained by its higher reducibility as a result of lower interaction of the cobalt oxide with the SBA-15. The fine dispersion of cobalt and cerium oxide and their strong interaction in the channels of the SBA-15 molecular sieve, leads to the formation of difficult-to-reduce oxide phases and, consequently, to lower catalytic activity compared to monocomponent cobalt oxide catalyst. The synthesised mesoporous structure can prevent the agglomeration of the oxide particles, thus leading to the successful development of a new and stable catalyst for decreasing greenhouse gas emissions.

Reaction Kinetics and Mechanism of VOCs Combustion on Mn-Ce-SBA-15

“…This effect could be attributed to the decrease in the manganese concentration on the surface (as can be seen from XPS data), the decrease in the reducible oxygen species and to the fact that in bi-component catalysts, the oxide particles are situated inside the channels and are less accessible to the reagents. A similar phenomenon was observed with Co-Mn catalysts obtained by the same "two-solvent" method [45] and Co-Ce catalysts [46]. According to the TEM images, the oxide particles are located in the channels of the mesoporous structure and there is a strong interaction between manganese oxide and cerium oxide.…”

Mechanochemically Prepared Co3O4-CeO2 Catalysts for Complete Benzene Oxidation

“…In some cases, decreasing Co 3 O 4 reducibility of supported Co-Ce mixed oxides was observed [38] but the reason could be related to the role of ceria in higher dispersion and accordingly stronger interaction with the support as it was supposed in Ref. [31].…”

“…The best performance in the case of Co/Ce = 10:1 was related to the higher amount of lattice oxygen, active at low temperatures, high concentration of Co 3+ species, oxygen vacancies, and Ce 4+ /Ce 3+ redox couples. Differently, in a very recent paper [31], Blin and co-authors studying Co-Ce catalysts supported on mesoporous SBA-15 (prepared by 'two solvent' technique) in combustion of methane, propane, and n-hexane have established lower catalytic activity as compared to that of the mono-component cobalt oxide catalyst, whose highest activity was explained by enhanced reducibility because of weaker interaction with the SBA-15 support. On the contrary, the strong interaction of finely dispersed cobalt and cerium oxide in the SBA-15 channels resulted in difficult to reduce oxide phases and, respectively, in lower oxidation activity.…”

“…In the following years, the scientific interest in these catalytic systems continued. More recent publications for the combustion of commonly studied VOCs (without focusing on formaldehyde and halogenated hydrocarbons) referred to Co 3 O 4 -CeO 2 [23][24][25][26][27][28] and supported Co 3 O 4 -CeO 2 catalysts [29][30][31]. Differently prepared Co-Ce mixed oxides were tested in ethyl acetate [23,24] and toluene [25] abatement as model reactions.…”

Coupling effect of reaction conditions on the catalytic activity of Cu–Mn composite oxide catalysts for toluene

“…It has become one of the most promising treatment technologies due to its low energy consumption and high efficiency. 9,10 Catalysts consist of an active component and a carrier, and depending on the active component, they can be classied as noble metal catalysts (Au, Pd, Pt, and so on) [11][12][13] and transition metal catalysts (Co, Cu, Mn, and so on). 7,14 Although the noble metal catalysts have a high catalytic activity at low temperatures, the properties of unsustainability, high cost, and susceptibility to sintering and carbon deposition, restrict their wide application in industry.…”