کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1682345 | 1010467 | 2009 | 4 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Investigation on the porosity of zeolite NU-88 by means of positron annihilation lifetime spectroscopy Investigation on the porosity of zeolite NU-88 by means of positron annihilation lifetime spectroscopy](/preview/png/1682345.png)
Seven well characterized zeolites were investigated by positron annihilation lifetime spectroscopy. The lifetime spectra were analysed in four discrete components. The third one was associated with ortho-positronium annihilation in the channels, framed in terms of infinite cylinders. Differences between the radii determined from the positron annihilation technique and X-ray diffraction data were found and explained in terms of the physical structure of the channel. An analogous study on a high-silica NU-88 zeolite gave a value of 0.33 nm for the corresponding radius, in agreement with Ar and N2 adsorption data as well as with the catalytic behaviour of this zeolite in several acid catalyzed reactions. The longest lifetime component in NU-88 reveals the existence of mesopores, with average radius of about 1.8 nm, which could explain the importance of hydrogen transfer reactions in this zeolite.
Journal: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms - Volume 267, Issue 15, 1 August 2009, Pages 2550–2553