SDY沸石及其非骨架铝的研究 Ⅱ.羟基和酸性

STUDY ON SDY ZEOLITE AND EXTRAFRAMEWORK ALUMINIUM Ⅱ.HYDROXYL GROUPS AND ACIDITY

采用IR和NH_3-TPD方法研究了Y型沸石经高温水热法处理所得的SDY样品,以及SDY再经化学方法处理(HCl,H_2Na_2EDTA和H_4EDTA)所得样品的性能和酸性。着重讨论了IR谱羟基振动区的羟基归属和酸性质,并探讨了脱铝过程中产生的非骨架铝(EFAL)对佛石酸性的贡献。结果表明,EFAL可以无定形铝形式沉积于沸石的孔道中和以离子形式定位于沸石中的阳离子位上。沉积在孔道中的无定形EFAL对沸石酸性的贡献不明显,而居于沸石中阳离子位置上的EFAL对沸石的酸性有贡献。

IR and NH3-TPD techniques have been used to study the acidity of SDY zeolite and the samples obtained by extraction treatment of SDY by HC1, H2Na2EDTA and H4EDTA respectively. The assignment and the acidity of hydroxyl groups in the IR spectra. and also the contribution of the extraframework aluminium (EFAL) to the acidity of dealuminated Y zeolites were discussed emphatically. The results showed that EFAL could not only locate at cation, sites as ionic species, but also deposit in the pores as amorphous phase, the amorphous EFAL had no significant contribution to the acidity of the samples. Only those EFAL at cation sites were acidic.