Shape-selective alkylation and related reactions of mononuclear aromatic hydrocarbons over H-ZSM-5 zeolites modified with lanthanum and cerium oxides
Shape-selective alkylation and related reactions of mononuclear aromatic hydrocarbons over H-ZSM-5 zeolites modified with lanthanum and cerium oxides
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DOI：
10.1016/j.apcata.2005.10.024
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发表时间：
2006-01
影响因子：
5.5
通讯作者：
Y. Sugi;Y. Kubota;K. Komura;N. Sugiyama;M. Hayashi;Jong Ho Kim;G. Seo
中科院分区：
文献类型：
--
作者：
Y. Sugi;Y. Kubota;K. Komura;N. Sugiyama;M. Hayashi;Jong Ho Kim;G. Seo
研究了La_2O_3和CeO_2对H-ZSM-5分子筛的改性，以改善其在单核芳烃烷基化及相关反应中的择形性。在乙苯乙基化反应中，对二乙苯异构体的选择性得到了提高，而催化活性没有明显损失。La 2 O3改性比CeO 2改性更有效地提高了p-DEB的选择性。这些氧化物的选择性的改善是由于防止了p-DEB在外部酸位点的异构化。La_2O_3改性的H-ZSM-5分子筛的对位选择性提高是由于通过调节孔入口和使外酸中心失活使p-DEB优先扩散而产生的“产物选择性”。在La_2O_3和CeO_2改性的H-ZSM-5分子筛上，甲苯的异构化反应和二甲苯异构化反应中，二甲苯异构体的生成量明显增加。
The La2O3and CeO2modifications of H-ZSM-5 zeolites were examined to improve the shape-selectivity in the alkylation of mononuclear aromatic hydrocarbons and related reactions. The selectivities of p-diethylbenzene (p-DEB) among diethylbenzene isomers were improved without significant loss of catalytic activity by the modification with these oxides in the ethylation of ethylbenzene (EB). The La2O3modification enhanced the selectivities of p-DEB more effectively than the CeO2modification. The improvement of the selectivities over these oxides is due to the prevention of the isomerization of p-DEB at external acid sites. The para-selectivity for La2O3-modified H-ZSM-5 zeolites is improved due to “product selectivity” resulting from the preferential diffusion of p-DEB by the adjustment of pore entrance as well as by the deactivation of external acid sites. The enhancement of the formation of less bulky xylene isomer was also observed in the disproportionation of toluene and the isomerization of xylene isomers over La2O3- and CeO2-modified H-ZSM-5 zeolites.