分子筛 H-Mordenite 中 Brønsted 酸位的固态 MAS NMR 研究。

Solid-state MAS NMR studies of Brønsted acid sites in zeolite H-Mordenite.

机构信息

Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.

出版信息

J Am Chem Soc. 2012 Jun 13;134(23):9708-20. doi: 10.1021/ja301963e. Epub 2012 May 31.

DOI:10.1021/ja301963e

Abstract

(17)O-(1)H double resonance NMR spectroscopy was used to study the local structure of zeolite H-Mordenite. Different contact times were used in cross-polarization magic angle spinning (CPMAS) NMR, CP rotational-echo double resonance (CP-REDOR) NMR, and heteronuclear correlation (HETCOR) NMR spectroscopy to distinguish between Brønsted acid sites with different O-H distances. The accessibility of the various Brønsted acid sites was quantified by adsorbing the basic probe molecule trimethylphosphine in known amounts. On the basis of these experiments, locations of different Brønsted acid sites in H-Mordenite (H-MOR) were proposed. The use of (17)O chemical shift correlations to help assign sites is discussed.

摘要

(17)O-(1)H 双共振 NMR 光谱学被用于研究沸石 H-Mordenite 的局部结构。在交叉极化魔角旋转 (CPMAS) NMR、CP 旋转回波双共振 (CP-REDOR) NMR 和异核相关 (HETCOR) NMR 光谱学中使用了不同的接触时间，以区分具有不同 O-H 距离的布朗斯台德酸位。通过以已知量吸附碱性探针分子三甲基膦，定量了各种布朗斯台德酸位的可及性。基于这些实验，提出了 H-Mordenite (H-MOR) 中不同布朗斯台德酸位的位置。讨论了使用 (17)O 化学位移相关来帮助分配位的问题。