13-P-10-Evidence of partially broken bridging hydroxyls in molecular sieves from 1H MAS spin echo NMR spectroscopy

Abstract

This chapter presents evidence of partially broken bridging hydroxyls in molecular sieves from 1 H magic angle spinning (MAS) spin echo nuclear magnetic resonance (NMR) spectroscopy. By spin echo editing NMR method, combined with the l H ( 27 Al) spin echo double resonance, a new 1 H signal is found in the thermally treated molecular sieves, reflecting the complexity of hydroxyls as well as the aluminum state in the dehydrated state. It represents an initial stage of the dehydroxylation or may be related with the initial stage of dealumination.