کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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597708 | 1454072 | 2007 | 9 صفحه PDF | دانلود رایگان |
The self-formation phenomenon of hierarchy with multiple-scaled porosity is reported. The structures of various chemical compositions, such as ZrO2, TiO2, Al2O3, Y2O3, Nb2O5, Ta2O5 ZrO2-SiO2, ZrO2-TiO2, ZrO2-Y2O3, aluminosilicates, aluminophosphates, silicoaluminophosphates, metallophosphates, are made of macrochannels (0.5–5 μm in diameter) with mesoporous or microporous walls. The hierarchically porous structures are prepared by just controlling the hydrolysis and polycondensation rates of the pre-selected inorganic sources. The textural, structural as well as morphological properties of each material are carefully studied by using a large series of techniques, such as XRD, NMR, TEM, SEM, N2 adsorption-desorption, Hg porosimetry, optical microscopy. On the basis of these multimodal porous structures, a new concept “Hierarchical Catalysis” has been proposed. This new concept can allow the realisation of a multiple steps reaction in one single catalyst in a cascade way without any separation processes.
Journal: Colloids and Surfaces A: Physicochemical and Engineering Aspects - Volume 300, Issues 1–2, 1 June 2007, Pages 70–78