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应用吸附吡啶的红外光谱测定了11种国产氧化铝的表面酸性。结果表明,氧化铝上只有 Le-wis 酸(L 酸)中心,没检测出 Br(?)nsted 酸(B 酸)的红外吸收峰;红外吸收光谱随脱气温度的变化结果表明,Al_2O_3表面有两种强度不同的 L 酸中心;不同氧化铝表面酸量也不同,在合成乙胺反应中的活性和选择性随氧化铝表面酸性增大而升高。本工作还测定了η-Al_2O_3的表面 OH 基,观测到3785、3740和3710cm~(-1)三个吸收带,吸附吡啶后,3740cm~(-1)吸收带消失,表明该 OH 础为酸性羟基。
The surface acidity of 11 kinds of domestic alumina was determined by infrared spectroscopy of adsorbed pyridine. The results showed that there was only Le-w acid (L acid) center on alumina and no infrared absorption peak of Br (?) Nsted acid (B acid) was detected. The change of infrared absorption spectrum with degassing temperature showed that there was Two different L acid sites; the acidity of different alumina surfaces is also different, and the activity and selectivity in synthetic ethylamine reaction increase with the increase of acidity on the surface of alumina. In this work, the surface OH groups of η-Al_2O_3 were also measured. Three absorption bands of 3785, 3740 and 3710 cm -1 were observed. The adsorption band of 3740 cm -1 disappeared after adsorption of pyridine. Hydroxyl.