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Heterogeneous environmental catalysis – a gentle art: CeO2–ZrO2 mixed oxides as a case history

“…This route can therefore provide high textural stability [43,44], particularly under reducing conditions [45]; however, re-oxidation of such reduced species is not easy [46], resulting in deactivation of the OSC property. Only recently, there has been a renewed interest in this area [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], this being focused on the preparation and characterisation of nanostructured Ce x Zr 1Àx O 2 /Al 2 O 3 materials.…”

“…A perusal of the data in the literature reveals that addition of Al 2 O 3 to Ce x Zr 1Àx O 2 mixed oxides remarkably increases their thermal stability with respect to the unsupported oxides [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. As discussed above, special synthesis strategies are necessary to achieve reasonably good textural properties for the unsupported oxide for calcination temperatures around 1273-1373 K; on the other hand, a simple co-impregnation of ceria and zirconia precursors on the surface of Al 2 O 3 leads to high thermal stabilities with surface areas as high as 60-80 m 2 g À1 after calcination at 1273-1373 K for 5-100 h, provided that appropriate impregnation methodology is used, e.g.…”

Selectivity of Ethanol Conversion on Al/Zr/Ce Mixed Oxides: Dehydration and Dehydrogenation Pathways Based on Surface Acidity Properties

“…After heat treatment at 500 °C, the obtained diffraction peaks were very broad, making it difficult to identify the presence of the metastable tetragonal phases of zirconia [32] . The weakly formed diffuse reflexes were fixed in the regions corresponding to the phases of zirconium dioxide and transition forms of aluminum oxide (Figure 1a), as discussed in our previous study [32,33] . The crystalline forms of Al 2 O 3 were not identified because of the low intensity of the corresponding reflexes, determined by the nanoscale dimensionality of the objects [32] .…”

“…[32] The weakly formed diffuse reflexes were fixed in the regions corresponding to the phases of zirconium dioxide and transition forms of aluminum oxide (Figure 1a), as discussed in our previous study. [32,33] The crystalline forms of Al 2 O 3 were not identified because of the low intensity of the corresponding reflexes, determined by the nanoscale dimensionality of the objects. [32] However, the Al-rich oxides A50CZ and A75CZ showed very broad diffraction peaks at 2θ values of 45.9°and 66.7°, respectively, which correspond to the γ-alumina phase.…”

EPR characterization of Cu/Al‐Zr‐Ce ethanol dehydrogenation catalysts: Active site development and coking control

“…At the same time, the isolated CuO molecules were stabilized on the samples with the ACZ‐500 substrate. Thus, the less crystalline structure of the substrate [ 45 ] (ACZ‐500) contributes to the formation of the incorporated isolated CuO molecules on the surface, firmly bound to the defective surface, which prevents the transition of these forms of copper to the aggregated state. (Figure 5).…”