Catalytic dehydration of methyl lactate: Reaction mechanism and selectivity control
Catalytic dehydration of methyl lactate: Reaction mechanism and selectivity control
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DOI：
10.1016/j.jcat.2016.03.026
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发表时间：
2016-07-01
影响因子：
7.3
通讯作者：
Xu, Bingjun
中科院分区：
文献类型：
--
作者：
Murphy, Brian M.;Letterio, Michael P.;Xu, Bingjun
乳酸及其酯的催化脱水是一种很有前途的再生生产丙烯酸及其酯的方法。通过反应性和原位透射傅里叶变换红外（FTIR）光谱研究，对NaY的脱水反应机理进行了分子水平的了解。在水的帮助下原位生成的Bronsted酸位点已被确定为脱水途径的主要活性位点。所需的脱水和不需要的脱碳途径之间的关键分支点是乳酸甲酯在NaY上的解离，形成吸附的乳酸钠和甲基。Bronsted和Lewis酸位点主要催化吸附的乳酸钠脱水，而当乳酸甲酯未解离时，乙醛脱碳途径占主导地位。类似的机理步骤可能在乳酸催化脱水制丙烯酸的过程中遵循。所获得的机理理解将有助于合理设计选择性脱水乳酸甲酯的催化剂。(C) 2016 Elsevier Inc.版权所有。
Catalytic dehydration of lactic acid and its esters is a promising approach to renewably produce acrylic acid and its esters. Molecular level understanding of the dehydration reaction mechanism on NaY has been achieved via a combination of reactivity and in-situ transmission Fourier transform infrared (FTIR) spectroscopic investigations. Bronsted acid sites generated in-situ with the assistance of water have been identified as the primary active sites for the dehydration pathway. The key branching point between the desired dehydration and undesired decarbonylation pathways is the dissociation of methyl lactate on NaY to form adsorbed sodium lactate and methyl groups. Bronsted and Lewis acid sites mainly catalyze the dehydration of adsorbed sodium lactate, whereas the decarbonylation pathway to acetaldehyde dominates when methyl lactate is not dissociated. Similar mechanistic steps are likely followed in the catalytic dehydration of lactic acid to acrylic acid. The mechanistic understanding gained will enable rational design of catalysts for selective dehydration of methyl lactate. (C) 2016 Elsevier Inc. All rights reserved.