Synthesis and Characterization of Ta2O5-ZrO2 Systems: Structure, Surface Acidity, and Catalytic Properties.

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• 作者：Bá ; rbara Samaranch ; Pilar Ram&iacute ; rez de la Piscina ; Guillaume Clet ; Marwan Houalla ; Patrick Gé ; lin ; Narc&iacute ; s Homs
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：March 20, 2007
• 年：2007
• 卷：19
• 期：6
• 页码：1445 - 1451
• 全文大小：191K
• 年卷期：v.19,no.6(March 20, 2007)
• ISSN：1520-5002

文摘

The preparation of binary materials based on Ta₂O₅-ZrO₂ by a sol-gel method and with a widerange of compositions is reported (Ta₂O₅ nominal content from 4 to 74% w/w). Materials werecharacterized by X-ray diffraction, and infrared and Raman spectroscopy. Their acidic characteristicswere evaluated from the model reaction of 2-propanol dehydration and the adsorption of CO at 77 K and2,6-dimethylpyridine at 373 K, both followed by infrared spectroscopy. Increasing tantalum content bringsabout a development of a surface TaO_x phase followed by a progressive formation of aggregates ofamorphous Ta₂O₅. Increased stabilization of tetragonal zirconia was also observed with increasing Taloading. The surface area, number and strength of Brönsted acid sites, and the catalytic activity in the2-propanol dehydration increase with the increase in tantalum content up to ca. 50% w/w Ta₂O₅. Asurface area of 103 m² g^-1 was obtained for a solid with a Ta₂O₅ content of 53% w/w after calcinationat 873 K. The abundance of Brönsted acid sites, determined by lutidine adsorption, and their strength,determined by CO adsorption at 77 K, correlated with the catalytic activity in the 2-propanol dehydration.