Effect of alcohols as additives on the performance of a nano-sized Ru-Zn(2.8 % ) catalyst for selective hydrogenation of benzene to cyclohexene

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• 作者：Haijie Sun ; Houbing Jiang ; Shuaihui Li ; Yingying Dong ; Hongxia Wang ; Yajie Pan ; Shouchang Liu ; Mingsheng Tang ; Zhongyi Liu ; ^{liuzhongyi@zzu.edu.cn}
• 关键词：Benzene ; Hydrogenation ; Cyclohexene ; Ruthenium ; Zinc ; Hydrogen bond
• 刊名：Chemical Engineering Journal
• 出版年：2013
• 出版时间：15 February, 2013
• 年：2013
• 卷：218
• 期：Complete
• 页码：415-424
• 全文大小：1378 K

文摘

In liquid phase hydrogenation of benzene, Ru-Zn(2.8 % ) catalyst (Ru-Zn catalyst with the Zn mass percentage of 2.8 % ) exhibited the excellent selectivity to cyclohexene for the nano-size effect and the chemisorbed ZnSO₄¡¤3(ZnOH)₂?7H₂O salt formed by the promoter ZnO reacting with ZnSO₄. It is found that the cyclohexene yield of Ru-Zn(2.8 % ) catalyst generally increased with the molecular weight of PEG (Polyethylene glycol) in the presence of ZnSO₄. PEG-10000 (Polyethylene glycol with the molecular weight of 10,000) as an additive made Ru-Zn(2.8 % ) catalyst give the highest cyclohexene yield of 62.3 % in presence of ZnSO₄ for the following two reasons. Firstly, the addition of PEG-10000 in presence of ZnSO₄ could make more Zn²⁺ chemisorbed on the surface of the catalyst. The Zn²⁺ ions chemisorbed could be beneficial for stabilizing the formed cyclohexene, accelerating the desorption and hindering the re-adsorption of cyclohexene on the surface of the catalyst. Secondly, the PEG-10000 added might form two molecular hydrogen bonds in eight-numbered rings with the cyclohexene in the liquid phase, which could stabilize the cyclohexene in the liquid phase and hinder the re-adsorption. 2 g of this catalyst with 0.2 g PEG-10000 as an additive pretreated in presence of ZnSO₄ gave a selectivity to cyclohexene of 78.6 % and the best cyclohexene yield of 64.5 % at the benzene conversion of 82.0 % at 15 min. Moreover, this catalyst had an excellent stability since ZrO₂ and PEG-10000 could effectively inhibit the agglomeration of Ru-Zn(2.8 % ) catalyst.