Influence of the Chemical Nature of the Support (Niobic Acid and Niobium Phosphate) on the Surface and Catalytic Properties of Supported CuO
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- 作者：A. Gervasini ; P. Carniti ; S. Bennici ; C. Messi
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：March 20, 2007
- 年：2007
- 卷：19
- 期：6
- 页码：1319 - 1328
- 全文大小：362K
- 年卷期：v.19,no.6(March 20, 2007)
- ISSN：1520-5002
文摘
The morphologic (N2 adsorption and SEM), structural (XRD and FT-IR), redox (TPR/TPO cycles),acidic (TPD of 2-phenylethylamine), and surface (XPS) properties of supported CuO phases on niobicacid (Nb2O5·nH2O, labeled as NBO) and niobium phosphate (NbOPO4, labeled as NBP) materials werepresented together with their catalytic properties toward the decomposition and reduction of the N2O andNO species. An equilibrium adsorption method from copper acetate precursor was used to deposit thecopper phase over the two niobium supports (about 8 wt % loading). The prevalent covalent, for NBO,or ionic, for NBP, character of the support materials strongly affected the electronic properties of thesupported CuO phase, which was in nanosized aggregates in any case. The acidity of the Cu surfaceswas high because of the presence of acid sites of the support (prevalent Brönsted acid sites) and thoseassociated with dispersed metal species (Lewis acid sites). The CuO phase was better anchored on NBPthan on NBO, as shown by the very limited migration of the CuO species on NBP following reducingand oxidizing thermal treatments. The CuO surfaces showed different catalytic performances toward thereactions of N2O decomposition in inert and oxidant atmospheres and N2O and NO reduction by ethenein a highly oxidant atmosphere. CuO over NBO was more active than that over NBP in any case, whereasthe NBP support enhanced the reaction selectivity of the copper phase.