Wu Xinbang, Turnell-Ritson Roland C, Han Peijie, Schmidt Jaques-Christopher, Piveteau Laura, Yan Ning, Dyson Paul J
Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Department of Chemical Engineering, National University of Singapore, Singapore, Singapore.
Nat Commun. 2025 May 9;16(1):4322. doi: 10.1038/s41467-025-59688-0.
Polyurethane is a versatile plastic finding applications across diverse sectors ranging from construction to household products. Recently, there is growing interest in the chemical recycling of polyurethane via catalytic hydrogenation to recover anilines and polyols. However, examples of heterogeneous catalysts are lacking despite their practicality for scale-up to a commercially relevant level. Herein, the conversion of model carbamate compounds is investigated using different metal-oxide catalysts, with CeO exhibiting the best activity and achieving the highest yield of aniline products (up to 100% conversion and 92% yield of anilines). A volcanic correlation is found between the acidity of the metal-oxide catalysts and their activity in cleaving the carbamate bond. The high activity of CeO may be primarily attributed to a low oxygen vacancy formation energy and highly redox active Ce/Ce pairs. Based on control reactions under different conditions and in situ NMR studies, a mechanism for carbamate bond dissociation on CeO was proposed. Notably, both solvent-free hydrogenation and hydrogen-free transfer hydrogenation approaches may be utilized to depolymerize various commonly encountered polyurethane (thermoplastic and thermoset) products using CeO.
聚氨酯是一种用途广泛的塑料，在从建筑到家用产品等不同领域都有应用。最近，通过催化氢化对聚氨酯进行化学回收以回收苯胺和多元醇的兴趣日益浓厚。然而，尽管非均相催化剂对于扩大规模至商业相关水平具有实用性，但此类催化剂的实例却很缺乏。在此，使用不同的金属氧化物催化剂研究了模型氨基甲酸酯化合物的转化，其中CeO表现出最佳活性，并实现了苯胺产物的最高产率（高达100%的转化率和92%的苯胺产率）。发现金属氧化物催化剂的酸度与其裂解氨基甲酸酯键的活性之间存在火山型关联。CeO的高活性可能主要归因于低氧空位形成能和高氧化还原活性的Ce/Ce对。基于不同条件下的对照反应和原位核磁共振研究，提出了CeO上氨基甲酸酯键解离的机理。值得注意的是，使用CeO时，无溶剂氢化和无氢转移氢化方法均可用于解聚各种常见的聚氨酯（热塑性和热固性）产品。
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