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用红外光谱法研究热分解型HZSM-5沸石,发现在乙胺合成的HZSM-5沸石上至少存有三种不同类型的OH基。吡啶吸附的红外光谱表明,3605cm~(-1)谱带可以作为质子酸的表征,而以3740cm~(-1)谱带为代表的OH基,以氢键方式与呲啶结合。本研究还表明,在沸石上可能存在两种强度不同的L酸中心。900℃焙烧后尽管沸石的晶格依然完好,但所有OH基谱带均已消失,加水也只能使3740cm~(-1)谱带恢复,若用化学法除去该样品表面的阳离子后,3720cm~(-1)的谱带恢复,表明在焙烧过程中阳离子的迁移影响了OH基的水合。研究焙烧过程中沸石的变化情况推断件随着脱羟基反应,也存有骨架脱铝。
FTIR spectroscopy was used to study the pyrolytic HZSM-5 zeolite. It was found that there are at least three different types of OH groups on the HZSM-5 zeolite synthesized by ethylamine. The infrared absorption spectra of pyridine showed that the 3605cm -1 band could be characterized as the proton acid, while the OH group represented by the 3740 cm -1 band bonded to the pyridine by hydrogen bond. This study also shows that there may be two different L acid sites on the zeolite. After calcination at 900 ° C, all the OH-based bands disappear even though the crystal lattice of the zeolite is still intact. Adding water can only restore the 3740cm-1 band. If the surface of the sample is chemically removed, the 3720cm ~ (-1), indicating that the migration of cations affected the hydration of OH groups during the calcination. Study of the changes in zeolite roasting process inferred with the removal of hydroxyl reaction, there are also dealuminated skeleton.