Hydrogenative Depolymerization of Nylons
Hydrogenative Depolymerization of Nylons
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DOI：
10.1021/jacs.0c05675
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发表时间：
2020-08-19
影响因子：
15
通讯作者：
Milstein, David
中科院分区：
文献类型：
--
作者：
Kumar, Amit;von Wolff, Niklas;Milstein, David
普遍存在的塑料污染危机要求发现新的、可持续的方法来降解尼龙等坚固的塑料。使用一种基于氢化的绿色和可持续的方法，在150℃和70bar H-2的Ru钳形催化剂的存在下，我们在这里报告了通常被广泛使用的传统尼龙和聚酰胺的第一个氢化解聚的例子。在相同的催化条件下，我们还展示了聚氨酯加氢生成二元醇、二胺和甲醇的过程。此外，我们还展示了一个例子，在这个例子中，从加氢过程中获得的单体(和低聚物)可以被脱氢成分子量相近的聚寡聚酰胺，从而完成聚酰胺的闭合循环。在实验和密度泛函理论研究的基础上，我们提出了一个由金属-配体协作性促进的催化循环。总体而言，这种前所未有的转变，尽管是在概念验证层面上，提供了一种新的方法，以更清洁的方式回收尼龙。
The widespread crisis of plastic pollution demands discovery of new and sustainable approaches to degrade robust plastics such as nylons. Using a green and sustainable approach based on hydrogenation, in the presence of a ruthenium pincer catalyst at 150 degrees C and 70 bar H-2, we report here the first example of hydrogenative depolymerization of conventional, widely used nylons and polyamides, in general. Under the same catalytic conditions, we also demonstrate the hydrogenation of a polyurethane to produce diol, diamine, and methanol. Additionally, we demonstrate an example where monomers (and oligomers obtained from the hydrogenation process can be dehydrogenated back to a poly(oligo)amide of approximately similar molecular weight, thus completing a closed loop cycle for recycling of polyamides. Based on the experimental and density functional theory studies, we propose a catalytic cycle for the process that is facilitated by metal-ligand cooperativity. Overall, this unprecedented transformation, albeit at the proof of concept level, offers a new approach toward a cleaner route to recycling nylons.