Catalytic Chemical Sorting of Intractably Mixed Plastics

全球迫切需要制定更好的策略来回收塑料。据估计，到目前为止，总共生产了8.3亿公吨塑料，令人难以置信的是，在回收符号推出40多年后，只有不到10%的废塑料被回收利用。其余的要么被倒入垃圾填埋场，要么燃烧产生二氧化碳和其他有害气体，或者最糟糕的是，被丢弃到环境中。塑料将继续在满足我们社会日益增长的需求方面发挥关键作用，而从整体上消除这些需求并不是一个现实的解决办法。因此，一个关键的挑战是充分和有效地处理我们产生的废塑料。迫切需要为塑料垃圾提供更好的寿命终结选择。塑料回收的一个关键挑战是处理复杂的塑料废物，例如多层薄膜和混合物，其中的成分不能通过机械手段轻易分离，或者特定的组合在领先的化学回收方法中造成问题。WRAP的塑料流动2025报告估计，薄膜是仅次于瓶子的第二大消费塑料包装形式(2017年为395千吨)，其中只有4%被回收，这使这成为一个重要的技术目标。因此，在现有方法可能无法应用的领域，开发一种可以补充现有机械和化学方法的技术将是有利的-要么帮助从整体上解决最具挑战性的塑料废物流，要么为现有工艺提供更清洁、更有价值的废物流。这项工作建议发展“催化化学分类”。不同塑料中不同聚合物主链的不同化学成分意味着，可以利用特定官能团的反应性在存在另一种聚合物的情况下选择性地解聚一种聚合物，包括从混合物和混合物中解聚。这一概念的推广将使复杂塑料废物的顺序、选择性解聚成为可能。为了实现这一目标，我们将使用混合计算和实验方法从根本上推进解聚催化系统，以识别和开发能够实现选择性和容忍真实塑料废物的复杂性的铅系统，例如同一塑料中的添加剂、杂质、污染物和隐含的聚合物混合物。本项目专注于发展对催化的理解和基本应用，以应对这一挑战，然而，鉴于塑料回收的重要性，研究将以我们项目合作伙伴的见解为指导，以便在项目完成后，科学方法适合于使用已开发的化学和计算工具针对行业特定的挑战进行开发。

There is an urgent global need to devise better strategies to recycle plastics. It is estimated that a total of 8300 million metric tonnes of plastics have been produced to date yet, incredibly, more than 40 years after the launch of the recycling symbol, less than 10% of waste plastics that have been manufactured are recycled. The rest are either poured into landfill, burned to produce CO2 and other harmful gases or, worst of all, discarded into the environment. Plastics will continue to be critical in addressing the growing demands of our society and to eradicate them as a whole is not a realistic solution. A key challenge therefore is fully and effectively dealing with the waste plastics that we generate. Better end-of-life options for plastic waste are urgently required. A key challenge in plastic recycling is addressing complex plastics wastes, exemplified by multilayer films and blends in which the components cannot be readily separated by mechanical means or in which the specific combinations cause problems in the leading chemical recycling methodologies. WRAP's Plastic Flow 2025 report estimates that, after bottles, film is the next largest consumer plastic packaging format (395kt in 2017) of which just 4% was recycled, making this an important technological target. Hence the development of a technology that can complement existing mechanical and chemical methods would be advantageous in areas where current methods may not be possible to apply - to either help address the most challenging plastic waste streams in their entirety or to provide cleaner, more valuable, waste streams for existing processes.This work proposes to develop 'catalytic chemical sorting'. The different chemistry of different polymer backbones in different plastics means that the reactivity of the specific functional groups can be leveraged to selectively depolymerise one polymer in the presence of another, including from mixtures and blends. Extension of this concept would enable the sequential, selective depolymerisation of complex plastic wastes. In order to achieve this, we will fundamentally advance catalytic systems for depolymerisation using a hybrid computational and experimental approach to identify and develop lead systems that can achieve selectivity and be tolerant of the complexities of real plastic wastes, such as additives, impurities, contaminants and implicit polymer mixtures within the same plastic. This project is focussed on the development of the understanding and fundamental application of catalysis to this challenge, however, given the importance of plastic recycling, the research will be guided by insights from our project partners such that on completion of the project, the scientific approach is suitable for development towards industry-specific challenges using the chemistry and computational tools that have been developed.