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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 deuterated pyridine and trimethylphosphine (TMP) as basic probe molecules, Br # nsted acid (B) in the dealuminated and non-dealuminated microporous HY zeolites was analyzed by 1H and 31P magic angle rotation (MAS) Acid), we found that in the dealumination HY, the amount of B acid adsorbed on the probe molecule is more than that before adsorption, whereas the amount of B acid measured before and after adsorption of pyridine molecule in the HY sample without dealumination Were basically the same, confirming the existence of alkali “induced” B sites in the microporous molecular sieves, that is, SiOH near the end of aluminum can form bridged hydroxyl groups (SiOHAl) under the induction of basic probe molecules. The formation mechanism of B acid sites is discussed.