2017年1月
Hydrothermal synthesis of a layered-type W-Ti-O mixed metal oxide and its solid acid activity
CATALYSIS SCIENCE & TECHNOLOGY
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- 巻
- 7
- 号
- 1
- 開始ページ
- 243
- 終了ページ
- 250
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1039/c6cy02198k
- 出版者・発行元
- ROYAL SOC CHEMISTRY
A layered-type W-Ti-O mixed oxide was synthesized by hydrothermal synthesis from an aqueous solution of ammonium metatungstate and titanium sulfate. To avoid the formation of titania, oxalic acid was used as a reductant. Optimized synthesis led to rod-like particles comprised of MO6 (M = W, Ti) octahedra connected in a corner-sharing fashion in the c-direction and in the form of micropore-containing {W6O21} units in the a-b plane. The surface area, acidity and acid catalytic activity (alkylation) increased with the amount of the layered-type W-Ti-O phase. Strong Bronsted acid sites formed due to the thermal release of ammonia from the uncalcined precursor. Calcination at 400 degrees C led to the highest acidity and alkylation activity. Alkylation of benzyl alcohol and toluene led to heavy product formation due to over-alkylation of the product. The selectivity to the mono-alkylated product was improved by the addition of water, which competes with the selectively formed products for adsorption on the acid sites. FT-IR measurements showed that the layered-type W-Ti-O possesses Bronsted acid sites and at least two different Lewis acid sites. The stronger Lewis acid sites can be converted into Bronsted acid sites in the presence of water, and the weaker Lewis acid sites functioned in the presence of water. This water tolerance of Lewis acid sites is an important characteristic of layered-type W-Ti-O, as it allows the bifunctional catalyst to convert 1,3-DHA into lactic acid in water.
- リンク情報
- ID情報
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- DOI : 10.1039/c6cy02198k
- ISSN : 2044-4753
- eISSN : 2044-4761
- Web of Science ID : WOS:000392399900022