Abstract
A series of dealuminated zeolites Y with framework nSi/nAl ratios of 2.8−6.0 was prepared by steaming and characterized by atomic emission spectroscopy and 1H, 27Al, and 29Si NMR spectroscopy. The steaming of zeolite H-Y was performed under water vapor pressures of 3.4−81.5 kPa and at a temperature of 748 K. To exclude an additional modification of the dealuminated zeolites Y, the samples were investigated in the nonhydrated state, i.e., without hydration after the dealumination. By 29Si magic-angle spinning (MAS) NMR spectroscopy, a strong high-field shift of the signals of Si(3Al) and Si(2Al) sites in the spectra of nonhydrated zeolites Y in comparison with those of the hydrated samples was observed. This finding is explained by a change of the Si−O−T bond angles of Si(nAl) sites in the local structure of nonhydrated framework AlO4 tetrahedra. With increasing water vapor pressure during the dealumination, a systematic decrease of the total amounts of framework aluminum atoms in nonhydrated zeolites Y wa...
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
