Vanadium oxide supported on mesoporous MCM-41 as new catalysts for dehydrogenation of ethylbenzene with CO₂

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• 作者：Yanyan Qiao ; Changxi Miao ; Yinghong Yue ; Zaiku Xie ; Weimin Yang ; Weiming Hua ; Zi Gao
• 关键词：Supported vanadium oxide catalyst ; Mesoporous MCM-41 ; Ethylbenzene dehydrogenation ; Carbon dioxide ; Styrene
• 刊名：Microporous and Mesoporous Materials
• 出版年：2009
• 出版时间：1 March 2009
• 年：2009
• 卷：119
• 期：1-3
• 页码：150-157
• 全文大小：708 K

文摘

A series of MCM-41-supported vanadia catalysts (VO_x/MCM-41) with the vanadium loading of 0.5–3.0 mmol/g were studied with respect to their performance in the dehydrogenation of ethylbenzene to styrene in the presence of CO₂. Structural and textural characterizations of the catalysts were performed by means of N₂ adsorption, X-ray diffraction (XRD), UV–vis and Raman spectroscopy, and temperature-programmed reduction (TPR). These catalysts were found to be effective for the dehydrogenation reaction. The dispersity and the nature of the vanadium species depend strongly on the V loading, so does the catalyst activity. It was confirmed that, during the dehydrogenation of ethylbenzene with CO₂ over VO_x/MCM-41, two reaction pathways, i.e., direct oxidative dehydrogenation of ethylbenzene with CO₂ (one-step pathway) and reaction coupling of simple dehydrogenation of ethylbenzene with the reverse water–gas shift (two-step pathway) occurred. Forty-one percent of styrene could be produced by the one-step pathway. The promoting effect of CO₂ in ethylbenzene dehydrogenation has been attributed to different reaction pathways in the presence and in the absence of CO₂ as well as a higher concentration of active V⁵⁺ species on the catalyst surface under CO₂ atmosphere. The MCM-41-supported vanadia is more active than the vanadia catalyst supported on conventional amorphous SiO₂.