Selectivity Control in the Catalytic Dehydration of Methyl Lactate: The Effect of Pyridine
Selectivity Control in the Catalytic Dehydration of Methyl Lactate: The Effect of Pyridine
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DOI：
10.1021/acscatal.6b00723
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发表时间：
2016-07
期刊：
影响因子：
12.9
通讯作者：
B. Murphy;Michael P. Letterio;Bingjun Xu
中科院分区：
文献类型：
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作者：
B. Murphy;Michael P. Letterio;Bingjun Xu
生物质衍生的乳酸甲酯催化脱水生产丙烯酸及其酯有望成为生产主要商品化学品的可再生途径。碱金属阳离子交换的沸石能够催化该反应;然而，对脱水途径的选择性控制仍然是一个挑战。通过结合动力学和透射光谱研究，我们证明，向反应进料中引入碱吡啶可以增加丙烯酸酯的选择性，同时抑制副产物的形成（即，乙醛和焦化）。与不存在吡啶的情况相比，当进料中包含吡啶（吡啶/乳酸甲酯1/10）时，期望的脱水和不期望的脱羰基途径的转换频率的比率（TOFDH/TOFAD）增加了1/20。透射红外光谱研究表明，脱羰活性的降低与脱羰反应中吡啶猝灭产生的布朗斯台德酸中心直接相关。
Catalytic dehydration of biomass-derived methyl lactate to produce acrylic acid and its esters promises a renewable route to produce a major commodity chemical. Alkali metal cation exchanged zeolites are capable of catalyzing this reaction; however, selectivity control toward the dehydration pathway remains a challenge. Through combined kinetic and transmission spectroscopic investigations, we demonstrate that introducing pyridine, a base, to the reaction feed increases selectivity to acrylates while inhibiting the formation of side products (i.e., acetaldehyde and coking). The ratio of the turnover frequencies for the desired dehydration and undesired decarbonylation pathways (TOFDH/TOFAD) increases by a factor of ∼20 when pyridine is included in the feed (pyridine/methyl lactate 1/10), in comparison to the case where pyridine is absent. Transmission FTIR investigations show that the reduced decarbonylation activity can be directly related to pyridine quenching Bronsted acid sites generated during the re...