کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
60574 47537 2016 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Hydrothermal synthesis of W–Ta–O complex metal oxides by assembling MO6 (M = W or Ta) octahedra and creation of solid acid
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Hydrothermal synthesis of W–Ta–O complex metal oxides by assembling MO6 (M = W or Ta) octahedra and creation of solid acid
چکیده انگلیسی


• Layered-structure-type tungsten and tantalum oxides (W–Ta–O) were synthesized.
• The synthesized W–Ta–O samples were the same layered-type materials.
• Strong acid sites were generated by ion exchange from Na+ to NH4+.
• We revealed the relationship between the strong acid sites and catalytic activity.
• The crystalline motif of W–Ta–O was an interconnection of MO6 and pentagonal units.

Layered-type tungsten and tantalum oxides (W–Ta–O) were synthesized by the hydrothermal method. The synthesized W–Ta–O showed characteristic peaks at 2θ = 22.7° and 46.2° in an X-ray diffraction pattern (Cu Kα), indicating linear corner sharing of MO6 (M = W, Ta) octahedra in the c-direction. The same layered-type materials were obtained with a wide range of W and Ta composition ratios using soluble Lindqvist-type tantalum polyoxometalate (Na8(Ta6O19)·24.5H2O). Na+ cations of as-synthesized W–Ta–O were replaced with NH4+ and then calcined at 500 °C to form Brønsted acid sites. The catalytic activity of W–Ta–O increased with increasing W ratio, suggesting that strong acid sites were generated. From Raman and adsorption measurements of W–Ta–O with various crystalline structures, it was revealed that the crystalline motif of W–Ta–O in the a–b plane was an interconnection of MO6 (M = W, Ta) octahedra and {M6O21} pentagonal units and micropore channels, but without long-range order.

Figure optionsDownload high-quality image (170 K)Download as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 339, July 2016, Pages 143–152
نویسندگان
, , ,