摘要
用离子静电势、弱酸中毒法及红外光谱法表征了交换型和浸渍型碱金属离子沸石的酸碱性,并将其与对二甲苯-甲醇的侧链烷基化反应的活性和选择性相关联。结果表明,反应活性和选择性与催化剂酸碱性之间有较好的关系。Rb^+,Cs^+浸渍的LiX,NaX,KX沸石,通过Rb^+,Cs^+离子与体系的相互作用,被“诱发”成为有明显碱性功能的沸石催化剂。从红外光谱观察到碱金属离子沸石有一定强度的碱中心吸收带。还观察到LiX,NaX沸石上的呲啶吸附中心。
The side-chain aikylation of p-xylcne with methanol on alkali cation exchanged and impregnated zeolite catalysts has bcen studied. The acidity and basicity of the catalysts were characterized by the electrostatic potential of the cation, poisoning with phenol and the infrared spectra of adsorbed acetic acid and pyridine. The results show that the activity and selectivity for the side-chain aikylation are related to the acid-base properties of the catalysts, and depend on the cation ionic radius. For the impregnated zeolites, their basicity is induced by the interaction of the impregnated Rb 01 Cs with the system, and thus the catalysts have an obvious basic function. IR spectra of adsorbed acetic acid or pyridine show that there are base sites on all alkali cation zeolites and pyridine-adsorbed sites on LiX and NaX zeolites.
