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A series of Ce1− xCu xO2 (0 ≤ x ≤ 0.1) nanostructured oxide systems was prepared using a modified reverse microemulsion method. The thermal decomposition of the carbonate and hydroxide precursors into oxides systems was studied using thermal analysis methods (EGA-TGA/DTG/SDTA). The morphology and the structure of the samples were characterized by XRD and BET analysis as well as visualized by scanning electron microscopy (SEM). The morphology of the obtained nanoparticles depended on a kind of the precursors used. The copper substituted CeO2 materials formed mono phase solid solutions, which were catalytically active in the incineration of various VOC molecules (ethylene, methanol, acetone). The correlation between activity of the studied catalysts and copper content has been found. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: SBA-15 mesoporous silica was modified with metal (Al, Ti, Cu, Fe) oxides by the molecular designed dispersion (MDD) method using acetylacetonate complexes of metals as precursors of the catalytically active components. The modified mesoporous silicas were characterized with respect to texture (BET), composition (EPMA), coordination and aggregation of transition metal species (UV–vis-DRS), reducibility of the deposited transition metals (TPRed) and surface acidity (FT-IR). Deposition of aluminium and titanium species on the SBA-15 surface significantly increased its acidity, mainly by generation of strong Lewis acid sites. Copper and iron deposited on the surface of pure SBA-15 were present nearly exclusively in the form of mononuclear cations. Deposition of Fe or Cu on the SBA-15 supports modified with alumina or titania resulted in a formation of significant amounts of oligomeric metal oxide clusters. The SBA-15 based samples have been found to be active and selective catalysts of the DeNO x process. The modification of the silica surface with titanium or aluminium prior to the deposition of iron or copper significantly improved the activity of the SBA-15 based catalysts. [Copyright &y& Elsevier]

Abstract: Vermiculites intercalated with alumina pillars and modified with transition metals (Cu, Fe) were studied as catalysts of selective reduction of NO with ammonia. Prior to the pillaring process, a raw vermiculite was treated with a solution of nitric acid and then citric or oxalic acid in order to reduce the overall charge of layers. This modification was necessary for a successful pillaring of the clay. Transition metals (Fe, Cu) were deposited on the surface of the modified vermiculites by an ion-exchange method. The obtained samples were characterized with respect to composition (EPMA), structure (XRD), texture (BET) and chemical nature of deposited transition metal species (UV–vis–DRS). The vermiculite based materials have been found to be active and selective catalysts of the DeNOx process. The Cu-containing samples were catalytically active at lower temperatures than the pillared clays modified with iron. A side reaction of ammonia oxidation by oxygen decreased the effectiveness of the DeNOx process in the high temperature range. [Copyright &y& Elsevier]

Abstract: Porous clay heterostructures (PCH) obtained on the basis of the synthetic saponite was used as a catalytic support for the deposition of transition metal (Cu, Fe) oxides. Transition metal oxides were introduced into the parent as well as ammonia treated PCH support by the ion-exchange method. The obtained catalysts were characterized with respect to their textural parameters (BET), composition (EPMA), chemical nature of the introduced transition metal species (UV–vis–DRS) and surface acidity (NH3-TPD, FTIR). The modified PCH materials were tested as catalysts for the selective oxidation of ammonia to nitrogen and water. The studied catalysts have shown a very high selectivity towards N2, which did not drop below 90% in a large studied temperature range (150–550°C). However, the Cu-containing samples were active at temperatures significantly lower than PCH modified with iron. [Copyright &y& Elsevier]