物理化学学报 >> 2006, Vol. 22 >> Issue (10): 1233-1237.doi: 10.1016/S1872-1508(06)60058-2

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用固体核磁共振谱定量研究脱铝HY分子筛中碱“诱导”的Brö nsted酸性位

胡伟;罗晴;李申慧;申万岭;岳勇;邓风   

  1. 中国科学院武汉物理与数学研究所, 波谱与原子分子物理国家重点实验室, 武汉 430071
  • 收稿日期:2006-04-20 修回日期:2006-05-27 发布日期:2006-10-11
  • 通讯作者: 邓风 E-mail:dengf@wipm.ac.cn

Base-induced Brönsted Acid Sites on Dealuminated HY Zeolite: A Solid-state NMR Spectroscopy Study

HU Wei;LUO Qing;LI Shen-Hui;SHEN Wan-Ling;YUE Yong;DENG Feng   

  1. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
  • Received:2006-04-20 Revised:2006-05-27 Published:2006-10-11
  • Contact: DENG Feng E-mail:dengf@wipm.ac.cn

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摘要： 用氘代吡啶和三甲基膦(TMP)作为碱性探针分子, 用1H和31P魔角旋转(MAS) NMR谱对脱铝和未脱铝微孔HY分子筛中的Brönsted酸(B酸)进行了定量研究. 发现在脱铝HY中, 吸附探针分子后的B酸量比吸附前的要多, 而在未脱铝的HY样中, 吸附吡啶分子前后测得的B酸量基本一致, 证实了在微孔分子筛中存在碱“诱导”B酸位, 即靠近铝的端位SiOH能在碱性探针分子的诱导下形成桥式羟基(SiOHAl). 对这种碱“诱导”B酸位的形成机制进行了讨论.

关键词: HY分子筛, NMR, 脱铝, 探针分子, &ldquo, 诱导&rdquo, B酸

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 the adsorption of the probe molecules, the concentration of Brönsted acid sites on the dealuminated HY zeolite increases by about 25%, whereas 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.

Key words: HY zeolite, NMR, Dealumination, Probe molecule, Induced Brö, nsted acid site