Force-activated organocatalysts for plastic recycling

用于塑料回收的强制激活有机催化剂

• 批准号: 2608091
• 金额: --
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2608091
• 关键词: Force; activated; organocatalysts; plastic; recycling

Synthetic polymers are used in almost every aspect of modern life. For this reason, they also present an important environmental challenge. Although some polymers can be easily recycled (e.g.), required costly and/or challenging processes. This is especially true if the plastic is composed of mixed polymers and/or if the recovery of the monomer is targeted. This step could be facilitated if plastic where embedded with an additive that could accelerate their degradation at the end of their life. This goal could be achieved by implementing mechanoresponsive molecules, called mechanophores, that react upon application of a force to generate a useful chemical entity. For example, a force-activated catalyst could be used to facilitate depolymerisation. In this project we will produce new mechanocatalysts based on varied NHC-precursors, and investigate their mechanocatalytic properties in solution, using ultrasound and in the solid state. Ultimately, we aim to produce a mechanocatalyst able to increase the degradability/depolymerisation of challenging commodity polymer (e.g. PET, PU) in recycling/processing conditions such as : extrusion or batch hydrolysis/aminolysis.Only a handful of mechanocatalysts have been reported but they are all metal-based, which make them expensive and difficult to process due to their low thermal and mechanical stability. The ideal mechanocatalyst is only activated when needed (and not for example during the production or the normal usage of the product). In other words, it must display a minimal sensitivity to a change in pH, temperature and humidity, but respond to a desired level of force. We have recently introduced a thermally-stable and environment-friendly alternative, based on a force-activated N-heterocyclic carbene (NHC) precursor (Nat. Chem. 2020, 12, 826; JACS 2021, 143, 3033). Recent heterogeneous catalysis work in CEAS has demonstrated that a number of pure polyolefin feedstocks (polyethylene, polypropylene and polystyrene) and blends of these three can be successfully hydrocracked rapidly at much reduced temperatures yielding a predominantly C3 - C9 hydrocarbons (Ind. Eng. Chem. Res., 58 (45), 20601; EP Patent 2437886B1 -2019). Further work on the condensation polymer, polyethylene terephthalate (PET) using hydrolysis has led to conversions of 80% with around 80% selectivity to terephthalic acid at 220oC in 90 minutes. This project will extend this current work and will target the production of a mechanocatalyst able to increase the depolymerisation of challenging commodity polymer [e.g. PET, polyurethane (PUR)] in recycling/processing conditions such as, extrusion or batch hydrolysis/hydrocracking.Objective 1: Catalyst design and optimisation of the mechanochemical and catalytic properties in solution Objective 2: Exploration of the mechanochemical and catalytic properties in the solid state/meltObjective 3: Investigation of various modes of activation in batch reactor (e.g. turbulent flow, vapor-induced elongational flow)Objective 4: Optimisation of the mechanochemical and catalytic properties in hydrolysis/hydrocracking conditions for PET and PU.With over 4.0 Mte of plastic waste being sent to landfill or incinerated annually in the UK (8 % is PET and a similar amount of PUR, PlasticsEurope, The Facts 2020), the development of integrated catalytic approaches for plastic recycling would allow us to make a significant and lasting contribution to this important area. The ability to control the lifecycle of polymers would have a dramatic impact on the flux of plastic waste (Nature 2016, 540, 363). Embedded molecular mechanisms act to prolong the life of high-performance polymers. The mechanocatalysts we propose to investigate could be used to implement self-degrading mechanisms in PET, PU, or polyamides to facilitate their degradation/depolymerisation at the end of their lifecycle.

合成聚合物几乎用于现代生活的各个方面。因此，它们也带来了重大的环境挑战。虽然一些聚合物可以很容易地回收（例如），需要昂贵和/或具有挑战性的过程。如果塑料由混合聚合物组成和/或如果以单体回收为目标，则尤其如此。如果塑料中嵌入了一种添加剂，可以在其寿命结束时加速其降解，则可以促进这一步骤。这一目标可以通过实施机械响应分子来实现，称为机械载体，其在施加力时反应以产生有用的化学实体。例如，力活化的催化剂可用于促进解聚。在这个项目中，我们将基于不同的NHC前体生产新的机械催化剂，并研究它们在溶液中，使用超声和固态下的机械催化性能。最终，我们的目标是生产一种机械催化剂，能够在回收/加工条件下提高具有挑战性的商品聚合物（如PET，PU）的降解性/解聚性，例如：挤出或分批水解/氨解。目前只有少数机械催化剂被报道，但它们都是金属基的，这使得它们昂贵且难以加工，因为它们的热稳定性和机械稳定性较低。理想的机械催化剂仅在需要时被激活（而不是例如在产品的生产或正常使用期间）。换句话说，它必须对pH值、温度和湿度的变化表现出最小的敏感性，但对所需的力水平做出响应。我们最近介绍了一种热稳定且环境友好的替代品，其基于力活化的N-杂环卡宾（NHC）前体（Nat. Chem. 2020，12，826; JACS 2021，143，3033）。CEAS中最近的多相催化工作已经证明，许多纯聚烯烃原料（聚乙烯、聚丙烯和聚苯乙烯）和这三种的共混物可以在低得多的温度下成功地快速加氢裂化，产生主要为C3 - C9烃（Ind. Eng. Chem. Res.，58（45），20601; EP专利2437886 B1 - 2019）。对缩聚物聚对苯二甲酸乙二醇酯（PET）的进一步研究使用水解导致在220 ° C下在90分钟内转化率为80%，对对苯二甲酸的选择性约为80%。该项目将扩展目前的工作，并将针对机械催化剂的生产，该催化剂能够在回收/加工条件下（如挤出或间歇水解/加氢裂化）增加具有挑战性的商品聚合物[例如PET、聚氨酯（PUR）]的解聚。目标1：催化剂设计和溶液中机械化学和催化性能的优化目标2：固态/熔体中机械力化学和催化性质的探索目标3：间歇反应器中各种活化模式的研究（例如湍流、蒸汽诱导的拉伸流）目的4：优化水解中的机械化学和催化性能/在英国，每年有超过4.0 Mte的塑料废物被送往垃圾填埋场或焚烧，（8%是PET和类似数量的PUR，PlasticsEurope，The Facts 2020），塑料回收综合催化方法的开发将使我们能够为这一重要领域做出重大而持久的贡献。控制聚合物生命周期的能力将对塑料废物的通量产生巨大影响（Nature 2016，540，363）。嵌入式分子机制可延长高性能聚合物的寿命。我们建议研究的机械催化剂可用于在PET、PU或聚酰胺中实现自降解机制，以促进其在生命周期结束时的降解/解聚。