Radhika N P, Selvin Rosilda, Kakkar Rita, Roselin L Selva
Department of Chemistry, University of Delhi, Delhi 110007, India.
Department of Basic Sciences and Humanities, Don Bosco Institute of Technology, Ka (W), Mumbai 400070, India.
J Nanosci Nanotechnol. 2018 Aug 1;18(8):5404-5413. doi: 10.1166/jnn.2018.15390.
In this paper, authors report the synthesis of nanocrystalline hierarchical zeolite ZSM-5 and its application as a heterogeneous catalyst in the alkylation of phenol with cyclohexene. The catalyst was synthesized by vacuum-concentration coupled hydrothermal technique in the presence of two templates. This synthetic route could successfully introduce pores of higher hierarchy in the zeolite ZSM-5 structure. Hierarchical ZSM-5 could catalyse effectively the industrially important reaction of cyclohexene with phenol. We ascribe the high efficiency of the catalyst to its conducive structural features such as nanoscale size, high surface area, presence of hierarchy of pores and existence of Lewis sites along with Brønsted acid sites. The effect of various reaction parameters like duration, catalyst amount, reactant mole ratio and temperature were assessed. Under optimum reaction conditions, the catalyst showed up to 65% selectivity towards the major product, cyclohexyl phenyl ether. There was no discernible decline in percent conversion or selectivity even when the catalyst was re-used for up to four runs. Kinetic studies were done through regression analysis and a mechanistic route based on LHHW model was suggested.
在本文中，作者报道了纳米晶分级沸石ZSM-5的合成及其作为多相催化剂在苯酚与环己烯烷基化反应中的应用。该催化剂是在两种模板存在下通过真空浓缩耦合水热技术合成的。这种合成路线能够成功地在沸石ZSM-5结构中引入更高层次的孔道。分级ZSM-5能够有效地催化环己烯与苯酚这一具有工业重要性的反应。我们将催化剂的高效率归因于其有利的结构特征，如纳米级尺寸、高比表面积、孔道层次结构的存在以及同时存在的Lewis酸位点和Brønsted酸位点。评估了反应持续时间、催化剂用量、反应物摩尔比和温度等各种反应参数的影响。在最佳反应条件下，该催化剂对主要产物环己基苯基醚的选择性高达65%。即使将催化剂重复使用多达四次，转化率或选择性百分比也没有明显下降。通过回归分析进行了动力学研究，并提出了基于LHHW模型的机理途径。
