Analysis of thermodynamics, kinetics, and reaction pathways in the amination of secondary alcohols over Ru/SiO2
Analysis of thermodynamics, kinetics, and reaction pathways in the amination of secondary alcohols over Ru/SiO2
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DOI：
10.1016/j.jcat.2023.05.003
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发表时间：
2023-05
影响因子：
7.3
通讯作者：
Xin Gao;Dia Sahsah;Andreas Heyden;Jesse Q. Bond
中科院分区：
文献类型：
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作者：
Xin Gao;Dia Sahsah;Andreas Heyden;Jesse Q. Bond
本工作考虑了钌介导的胺化仲醇与氨在蒸汽和液体介质。我们映射热力学约束，我们探测物种分压，停留时间，反应温度对速率，选择性和催化剂稳定性的影响。醇胺化不消耗H2，H2对胺化动力学没有显著影响;然而，在H2下操作有利于Ru稳定性。伯胺的选择性随着氨压力和醇转化率的增加而增加，并且后一观察结果与通过连续反应的网络形成伯胺一致。不幸的是，伯胺易受二次脱氨基作用而形成烃。作为寻求分离反应性中间体的典型工艺，这里的主要选择性挑战是确定停留时间，该停留时间足够长以积累高底物转化率，但足够短以避免二次脱氨基。通常，适度的停留时间将使伯胺的产量最大化。洞察力延伸到广泛的底物范围，我们观察到70 - 90%的伯胺产率来自线性，环状和杂环醇。也就是说，杂环醇似乎对产物抑制敏感，因此实现高转化率需要更长的停留时间和/或增加的氨压力。
This work considers the Ru-mediated amination of secondary alcohols with ammonia in vapor and liquid media. We map thermodynamic constraints, and we probe the impacts of species partial pressure, residence time, and reaction temperature on rate, selectivity, and catalyst stability. Alcohol amination consumes no H2, and H2has no significant impact on amination kinetics; however, operating under H2benefits Ru stability. Primary amine selectivity increases with ammonia pressure and alcohol conversion, and the latter observation is consistent with the formation of primary amines through a network of sequential reactions. Unfortunately, primary amines are susceptible to secondary deamination to form hydrocarbons. As is typical of processes that seek to isolate a reactive intermediate, the main selectivity challenge here is identifying residence times that are long enough to accumulate high substrate conversion but short enough to avoid secondary deamination. In general, moderate residence times will maximize the production of primary amines. Insights extend across a broad substrate scope, and we observe 70 – 90% yield of primary amines from linear, cyclic, and heterocyclic alcohols. That said, heterocyclic alcohols appear susceptible to product inhibition, so achieving high conversions requires longer residence times and/or increased ammonia pressures.