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用正丁胺滴定和吡啶—红外光谱法,研究了LaHY表面上酸性中心与NaOH的作用机理及酸性表面性质。NaOH与LaHY表面上酸性中心作用的计量比与正丁胺滴定时不同。中和同样数量的酸性中心所消耗NaOH的当量数比正丁胺多,其差值与Lewis酸的含量有关。假定NaOH与LaHY表面上酸性中心作用的机理为:一当量Bronsted酸与一当量NaOH作用,而一当量Lewis酸消耗两当量NaOH,则可借助正丁胺滴定和NaOH中和法测定Bronsted酸和Lewis酸的含量。红外光谱测定的结果支持这一观点。 研究结果还表明,LaHY表面的酸性分布是不均匀的,异丙苯裂解反应是在不同强度的酸性中心上进行的。不同强度的酸性中心对总活性的贡献不同,而贡献的大小又与反应温度有关。
Using n-butylamine titration and pyridine-infrared spectroscopy, the mechanism and acidic surface properties of acidic sites on the surface of LaHY and NaOH were studied. The molar ratio of NaOH to the acid sites on the LaHY surface is different from that of n-butylamine titration. Neutralization of the same number of acidic centers consumes more equivalents of NaOH than n-butylamine, the difference being related to the amount of Lewis acid. Assuming that the mechanism of action of NaOH on the surface of the LaHY acid center is that one equivalent of Bronsted acid and one equivalent of NaOH act, and one equivalent of Lewis acid consumes two equivalents of NaOH, n-butylamine titration and NaOH neutralization determine Bronsted acid and Lewis Acid content. Infrared spectrometry results support this view. The results also show that the surface of the LaHY acid distribution is uneven, cumene cracking reaction is carried out in different intensity of the acidic center. The contribution of acid sites of different intensities to total activity is different, and the contribution of these sites is related to the reaction temperature.