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

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

作　　者：胡伟[1] 罗晴[1] 李申慧[1] 申万岭[1] 岳勇[1] 邓风[1] 

机构地区：[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

出　　处：《物理化学学报》2006年第10期1233-1237,共5页Acta Physico-Chimica Sinica

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Br#nsted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.Using trimethylphosphine（TMP） and d5-pyridine （deuterated pyridine） as the basic probe molecules, the concentrations of Bronsted 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 Bronsted 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 Br6nsted acid sites is due to the appearance of base-induced Bronsted 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 （SiOHA1） in the presence of the basic probe molecules. The mechanism of formation of the induced Bronsted acid sites has also been discussed.

关 键 词：HY分子筛 NMR 脱铝 探针分子 “诱导”B酸 

分 类 号：O643.3[理学—物理化学]