Shifts in catalyst deactivation mechanisms as a function of surface coverage during Friedel-Crafts acylation in zeolites
Shifts in catalyst deactivation mechanisms as a function of surface coverage during Friedel-Crafts acylation in zeolites
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沸石傅克酰化过程中催化剂失活机制随表面覆盖度的变化
DOI：
10.1016/j.jcat.2023.07.009
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发表时间：
2023
影响因子：
7.3
通讯作者：
Crossley, Steven
中科院分区：
文献类型：
--
作者：
Alalq, Ismaeel;Nguyen-Phu, Huy;Crossley, Steven
利用可再生资源生产大宗化学品通常伴随着催化剂快速失活。一个重要的例子是直接弗里德尔克拉夫茨酰化，它可以产生一系列有价值的产品，从表面活性剂到可再生运输燃料。呋喃酰基受体是最有趣和最有前途的可能受体之一。然而，它们在布朗斯台德酸表面位点存在的情况下发生自偶联反应，导致催化剂快速失活。在这篇文章中，我们研究了在 160 至 240 °C 的温度下，在 HZSM-5 催化剂上用乙酸进行的 2-甲基呋喃酰化反应，揭示了失活行为随乙酸表面覆盖度的变化而发生的显着变化。我们发现，用乙酸饱和的表面通过阻止呋喃物质直接进入表面位点来降低失活率。然而，在羧酸完全饱和的表面上，失活是通过吸附产物与气相甲基呋喃反应物之间的反应进行的。
The production of commodity chemicals from renewable resources is often accompanied by rapid catalyst deactivation rates. An important example is direct Friedel Crafts acylation, which can yield a range of valuable products from surfactants to renewable transportation fuels. Furanic acyl acceptors are among the most intriguing and promising possible acceptors; however, they undergo self-coupling reactions in the presence of Brønsted acid surface sites leading to rapid catalyst deactivation. In this contribution, we study 2-methylfuran acylation with acetic acid over HZSM-5 catalysts at temperatures ranging from 160 to 240 °C, revealing the remarkable shift in deactivation behavior as a function of surface coverage of acetic acid. We reveal that a surface saturated with acetic acid lowers the deactivation rate by blocking the direct access of furanic species to surface sites. However, on surfaces fully saturated with carboxylic acids, deactivation is revealed to proceed via reactions between adsorbed products with gas phase methylfuran reactants.