Abstract

A series of lanthanide (Ln) modified zeolites, Pr/HZSM-5, Gd/HZSM-5, Ho/HZSM-5, and Yb/HZSM-5 have been prepared and characterized by XRPD, IR, and atomic absorption spectroscopies. In Ln/HZSM-5, concentration of the Brønsted acid sites decreases with the increase of ionic radii of Ln (Pr > Gd > Ho > Yb) and with the Ln loading, while concentration of the Lewis acid sites increases. The conversion of EB and production of diethylbenzenes (DEBs) over the Ln/HZSM-5 catalysts and parent HZSM-5 have been studied using a flow fixed-bed reactor; the reaction temperature was varied from 300 to 450°C. The m-DEB and p-DEB isomers are the main products at the studied conditions. The highest yield of DEBs of ca. 22.2% (7.8% m-DEB and 14.4% p-DEB) with EB conversion of 42.4% was obtained over 5 wt % Yb-HZSM-5 catalyst at 400°C.

中文翻译：

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Ln改性HZSM-5沸石催化乙苯歧化

摘要

制备了一系列镧系元素 (Ln) 改性沸石 Pr/HZSM-5、Gd/HZSM-5、Ho/HZSM-5 和 Yb/HZSM-5，并通过 XRPD、IR 和原子吸收光谱对其进行了表征。在 Ln/HZSM-5 中，布朗斯台德酸位点的浓度随着 Ln 离子半径的增加（Pr > Gd > Ho > Yb）和 Ln 负载量的增加而降低，而路易斯酸位点的浓度增加。使用流动固定床反应器研究了在 Ln/HZSM-5 催化剂和母体 HZSM-5 上 EB 的转化和二乙苯 (DEB) 的生产；反应温度在 300 至 450°C 之间变化。m -DEB 和p -DEB 异构体是研究条件下的主要产物。DEB的最高产量约为。22.2%（7.8% m- DEB 和 14.4% p-在 400°C 下，在 5 wt% Yb-HZSM-5 催化剂上获得 EB 转化率为 42.4% 的 DEB)。