~(27)Al-NMR studies on Al-MCM-41 molecular sieves synthesized with different Si/Al ratios and different aluminum sources

摘要

Al-MCM-41 molecular sieves in there sodium and hydrogen form with different Si/Al ratiosrn(16...256) were synthesized using aluminum sulfate and aluminum triisopropylate as source.rnIn all experiments the pH value was held at about 10 during the synthesis procedure. Thernproducts in the as-synthesized form and after calcination were characterized by means ofrnXRD diffraction, nitrogen adsorption-desorption, and two different techniques of the solidstatern~(27)Al MAS NMR spectroscopy. Applying the cross-polarization (CP) magic anglernspinning (MAS) spectroscopy makes it possible to determine the local environments of thernaluminum species and to distinguish better between framework and non-frameworkrnaluminum.