LaDAlY型沸石表面羟基和酸性的研究

应用红外光谱和NH₃-TPD法对LaDAlY型沸石的表面羟基和酸性进行了研究,从将La³⁺离子引入NH₄Y和DAlY后表面羟基的变化中探讨了La³⁺离子在NH₄Y和DAlY中的分布,吡啶吸附及脱附的红外光谱表明,在DAlY中引入La³⁺后B酸和L中心数均减少;NH₃-TPD的结果表明,在DAlY中引入La³⁺离子后,其弱酸中心的强度稍有增加,而强酸中心的强度基本不变,酸中心数一般减少,其结果与吡啶-IR结果一致。

Studies on the Surface OH Groups and Acidic Properties of LaDAIY

The surface hydroxyl groups and acidic properties of LaDAlY were examined by means of IR spectroscopy with pyridine adsorption and NH3-TPD method. From the variations of hydroxyl groups, it is shown that La3+ ions are located at different positions in NH4Y and DA1Y. The experiments further indicate that the number of both Bronsted and Lewis acid sites on DA1Y and NH4Y was decreased after La3+ ions-exchanged. The NH3-TPD results show that the strength of weak acid sites of DA1Y was increased, while the strength of strong acid sites was almost not changed after La3+ ions-exchanged, and the number of acid intes was decreased generally. The results are consistent with these obtained by infrared studies.