Thermally Responsive Supports for Enhanced Efficiency in PET Depolymerisation

热响应支撑可提高 PET 解聚效率

• 批准号: EP/Y003667/1
• 负责人: Joseph Wood
• 金额: $ 117.7万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY003667%2F1
• 关键词: Thermally; Responsive; Supports; Enhanced; Efficiency

There is an urgent need to devise processes for recycling plastics, with an estimated 460 million metric tonnes of plastics being utilised worldwide in 2019 alone, of which only 10% is recycled globally, the remainder going to incineration, landfill or export. Burning of polymers contribute to CO2 production, causing global warming, and pollution of rivers and oceans occurs through discarding to the environment. Current mechanical and thermal recycling techniques can be used to produce lower grade products such as clothing, insulation, garden and road furniture, but these have inferior colour or mechanical properties, in comparison to virgin polymer, necessitating chemical recycling to produce virgin monomer. The principal polymer selected for study in this proposal is PET, with its wide industrial and consumer applications in bottles, packaging and clothing. In the USA 30 % of PET is currently recycled, in the EU the figure is 52 %, whilst world demand for PET resin is ~23.5 million tonnes and production capacity ~30.3 million tonnes, making a potentially large feedstock for recycling. Virgin PET resin has a much higher value at £1084/tonne compared with used PET bottles priced at £222.50/tonne, making chemical recycling to produce the virgin polymer the more economically attractive route than mechanical or thermal recycling. Chemical recycling of PET can follow a number of routes including reaction with alcohols, glycols, amines and ammonia, sometimes catalysed by basic materials like sodium bicarbonate, or more recently developed ionic organocatalysts or metal salt/organic base dual catalysts. However potential scale up for industrial production is hampered by the difficulties of separating the catalyst from the product mixture and efficient recycling. Also, there is a need to isolate and purify the product BHET from a mixture which may contain contaminants from the polymer, including dyes and additives. This proposal aims to create solutions to these problems by developing supported catalysts and separation technologies to enable a scaled-up process for PET depolymerisation, which could potentially be deployed industrially. Catalyst supports will be developed based on thermally responsive polymers, which can be solubilised to contact the reacting mixture, or solidified via simple temperature cycling to aid recovery by filtration. Key considerations will include understanding the reaction kinetics of the system, including any mass transport resistances, and optimisation of reaction conditions to achieve an attractive rate of reaction. We will experiment with polymer structures to find the optimal catalyst/support combination. In addition to catalyst recovery by temperature cycling, we will study recovery of BHET product via membrane separation. Strategies will include testing of commercial membranes and development of mixed matrix membranes incorporating zeolites to enhance the permeate flow. The proposed technologies will provide more attractive and commercially viable solutions for chemical recycling. In order to realise the benefits of the research, we have engaged Project Partners from across the recycling and polymer production sectors including Dupont Teijin Films and Siemens PSE, and academic collaborator Pennsylvania State University. They will provide, or advise on, samples for depolymerisation, provide software, technical consultation on the work plan, access to facilities and advise on routes to commercialisation and impact delivery as outlined in their letters of support.

迫切需要为回收塑料设计工艺，估计仅在2019年在全球范围内使用了4.6亿吨塑料，其中只有10％在全球范围内被回收，其余的则是焚化，垃圾或出口。聚合物的燃烧有助于二氧化碳的产量，从而导致全球变暖，以及河流和海洋的污染是通过丢弃环境而发生的。当前的机械和热回收技术可用于生产诸如服装，隔热，花园和道路家具之类的低年级产品，但是与Virgin Polymer相比，这些产品具有较低的颜色或机械性能，这些颜色或机械性能是必要的化学回收来产生Virgin单体。该提案中选择的主要聚合物是宠物，其工业和消费者在瓶子，包装和衣物中的应用都广泛。在美国，目前有30％的宠物被回收，在欧盟，该数字为52％，而世界对宠物树脂的需求约为2350万吨，生产能力约为3030万吨，这可能是回收的大型预防量。 Virgin Pet树脂的价值要高得多，价格为1084英镑/吨，而二手PET瓶的价格为222.50英镑/吨，这使得化学回收可产生Virgin聚合物，比机械或热回收的途径更具经济吸引力。 PET的化学回收可以遵循许多途径，包括与醇，乙二醇，氨的反应，有时是由碳酸氢钠等基本材料或最近开发的离子有机催化剂或金属盐/有机碱基双催化剂催化的。但是，将催化剂与产品混合物和有效的回收利用的难度妨碍了工业生产的潜在规模。同样，有必要将产品BHET与可能包含来自聚合物（包括染料和添加剂）的污染物的混合物分离和纯化。该建议旨在通过开发支持的催化剂和分离技术来为这些问题创建解决方案，以实现宠物沉积的扩大过程，这可能会在工业上部署。将根据热响应式聚合物开发催化剂支撑物，可以将其溶解以与反应混合物接触，或通过简单的温度循环固化以通过过滤帮助恢复。主要考虑因素将包括了解系统的反应动力学，包括任何质量转运性，以及优化反应条件以实现有吸引力的反应速率。我们将尝试聚合物结构，以找到最佳的催化剂/支持组合。除了通过温度循环回收催化剂，我们还将通过膜分离研究BHET产物的恢复。策略将包括对商业膜的测试以及编码沸石以增强渗透流量的混合基质膜的发展。拟议的技术将为化学回收提供更具吸引力和商业上可行的解决方案。为了实现这项研究的好处，我们与杜邦Teijin Films和Siemens PSE在内的回收和聚合物生产领域的项目合作伙伴与学术合作者宾夕法尼亚州立大学聘用了项目合作伙伴。他们将提供或建议样品进行解聚，提供有关工作计划的软件，技术咨询，访问设施以及有关商业化路线和影响交付的顾问，如他们的支持信中所述。