中国科学技术大学包信和团队报道了二氧化碳有利于聚烯烃塑料在低温下升级回收为芳烃。相关研究成果于2024年3月15日发表在《国家科学评论》。

塑料是生产量最大的合成材料和最大的商品之一，用于人类生活的许多领域。将废塑料升级为增值化学品是一项全球性挑战。尽管在热解和加氢裂化方面取得了重大进展，主要导致热解油的形成，但一步催化升级循环到包括苯、甲苯和二甲苯（BTX）在内的增值芳烃，仍然受到高反应温度（>500oC）和低产率的限制。

该文中，研究人员报道了通过双功能Pt/MnOx-ZSM-5催化剂，CO₂促进聚烯烃及其塑料产品在300℃以下向芳烃的升级循环。ZSM-5催化聚烯烃的裂解和芳构化，同时产生氢气，而Pt/MnOx催化氢气与CO₂的反应，从而推动反应走向芳构化。同位素实验表明，每1.0 kg PE消耗0.2 kg CO₂，并且消耗的CO₂的90%被掺入芳香族产物中。此外，与仅产生0.33kg芳烃的传统热解或加氢裂化工艺相比，该新工艺产生0.63kg芳烃（BTX占60%）。通过这种方式，塑料垃圾和温室气体CO₂都转化为碳资源，为废塑料的联合循环和碳利用提供了一种新的策略。

附：英文原文

Title: CO2 facilitated upcycling of polyolefin plastics to aromatics at low temperature

Author: Ding, Yi, Zhang, Shuchi, Liu, Cheng, Shao, Yu, Pan, Xiulian, Bao, Xinhe

Issue&Volume: 2024-03-15

Abstract: Plastics are one of the most produced synthetic materials and the largest commodities, used in numerous sectors of human life. To upcycle waste plastics into value-added chemicals is a global challenge. Despite significant progress in pyrolysis and hydrocracking which mainly leads to formation of pyrolysis oil, catalytic upcycling to value-added aromatics including benzene, toluene and xylene (BTX) in one step is still limited by high reaction temperatures (> 500oC) and a low yield. We report herein CO2 facilitated upcycling of polyolefins and their plastic products to aromatics below 300oC, enabled by a bifunctional Pt/MnOx-ZSM-5 catalyst. ZSM-5 catalyzes cracking of polyolefins and aromatization, generating hydrogen at the same time while Pt/MnOx catalyzes the reaction of hydrogen with CO2, consequently driving the reaction towards aromatization. Isotope experiments reveal that 0.2 kg CO2 is consumed per 1.0 kg PE and 90% of the consumed CO2 is incorporated into the aromatic products. Furthermore, this new process yields 0.63 kg aromatics (BTX accounting for 60%), comparing favorably with the conventional pyrolysis or hydrocracking processes which produce only 0.33 kg aromatics. In this way, both plastic wastes and the greenhouse gas CO2 are turned into carbon resources, providing a new strategy for combined waste plastics upcycling and carbon utilization.

DOI: 10.1093/nsr/nwae097

Source: https://dx.doi.org/10.1093/nsr/nwae097