Temperature-dependent lineshape of 1H magic-angle spinning nuclear magnetic resonance spectra of acidic hydroxyl groups in zeolites

✍ Scribed by Toshihide Baba; Yoshihiro Inoue; Hiroshi Shoji; Takayoshi Uematsu; Yoshio Ono

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 485 KB
• Volume: 3
• Category: Article
• ISSN: 0927-6513
• DOI: 10.1016/0927-6513(94)00078-a

✦ Synopsis

The 1H magic-angle spinning nuclear magnetic resonance (1H MAS NMR) spectra of acidic (bridging) hydroxyl (OH) groups on H-ZSM-5 zeolites were measured from room temperature to 373 K. The signal broadens with increasing temperature, indicating that the delocalization of the protons occurs at a temperature as low as 313 K. The broadening phenomena are less pronounced for H-ZSM-5 with higher Si/A1 ratios, indicating that the proton migration occurs more easily in H-ZSM-5 with higher aluminium concentrations. On the other hand, the linewidth of the signal due to protons of the non-acidic silanol groups does not depend on the temperature. The temperature dependence of the linewidths was also observed for 1H MAS NMR spectra of mordenite and Y zeolite.