Variable Temperature ^1H MAS NMR : A Powerful Tool for the Investigation of Dynamic Properties of Acidic Protons in Zeolites

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The dynamic nature of the protons in zeolites such as H-ZSM-5, metallosilicates molecular sieves and heteropoly compounds was examined by temperature dependence of ^1H MAS NMR in the range of 298 and 473 K.The temperature dependent line shape of ^1H MAS NMR spectra of acidic protons in zeolites showed the first and unambiguous evidence for proton migration in zeolite structure. The dynamic property of protons was a more sensitive measure for the activity of protons than the static parameters such as NMR chemical shift and IR band position of OH bonds.The variable temperature ^1H MAS NMR is a very useful technique for understanding dynamic properties of protons in solid-acids. The dynamic property is an important factor influencing of the catalytic activity of a solid-acid catalyst.