Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7832435 | Acta Physico-Chimica Sinica | 2006 | 5 Pages |
Abstract
Using trimethylphosphine (TMP) and d5-pyridine(deuterated pyridine) as the basic probe molecules, the concentrations of Brönsted acid sites on both HY zeolite and dealuminated HY zeolite have been quantitatively determined using solid-state 1H and 31P magic-angle spinning (MAS) NMR. After adsorption of the probe molecules, the concentration of Brönsted acid sites on the dealuminated HY zeolite increases by about 25%, whereas that in the parent HY sample remains almost unchanged. The increase in the concentration of Brönsted acid sites is due to the appearance of base-induced Brönsted acid sites in the dealuminated HY zeolite. The terminal SiOH in the vicinity of the aluminum atom is “induced” to form a bridging hydroxyl group (SiOHAl) in the presence of the basic probe molecules. The mechanism of formation of the induced Brönsted acid sites has also been discussed.
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Authors
Wei Hu, Qing Luo, Shenhui Li, Wanling Shen, Yong Yue, Feng Deng,