Kratish Yosi, Marks Tobin J
Department of Chemistry and the Institute for Catalysis in Energy Processes (ICEP), Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208 3113, USA.
Angew Chem Int Ed Engl. 2022 Feb 21;61(9):e202112576. doi: 10.1002/anie.202112576. Epub 2021 Dec 16.
Using a mechanism-based solvent-free tandem catalytic approach, commodity polyester plastics such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) are rapidly and selectively deconstructed by combining the two air- and moisture-stable catalysts, Hf(OTf) and Pd/C, under 1 atm H , affording terephthalic acid (or naphthalene dicarboxylic acid for PEN) and ethane (or butane for PBT) in essentially quantitative yield. This process is effective for both laboratory grade and waste plastics, and comingled polypropylene remains unchanged. Combined experimental and DFT mechanistic analyses indicate that Hf(OTf) catalyzes a mildly exergonic retro-hydroalkoxylation reaction in which an alkoxy C-O bond is first cleaved, yielding a carboxylic acid and alkene, and this process is closely coupled to an exergonic olefin hydrogenation step, driving the overall reaction forward.
采用基于机理的无溶剂串联催化方法，通过将两种对空气和湿气稳定的催化剂Hf(OTf)₄和Pd/C在1个大气压氢气下结合，可快速且选择性地解构商品聚酯塑料，如聚对苯二甲酸乙二酯（PET）、聚对苯二甲酸丁二酯（PBT）和聚萘二甲酸乙二酯（PEN），以基本定量的产率得到对苯二甲酸（对于PEN则为萘二甲酸）和乙烷（对于PBT则为丁烷）。该过程对实验室级塑料和废塑料均有效，且混合的聚丙烯保持不变。结合实验和DFT机理分析表明，Hf(OTf)₄催化一个轻度放能的逆氢烷氧基化反应，其中首先断裂一个烷氧基C-O键，生成羧酸和烯烃，并且该过程与一个放能的烯烃氢化步骤紧密耦合，推动整个反应向前进行。
