Engineering of Plastic Degrading Enzymes

塑料降解酶工程

• 批准号: 2607949
• 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: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2607949
• 关键词: Engineering; Plastic; Degrading; Enzymes

The misuse of manmade plastics has resulted in an accumulation of non-degradable materials in the biosphere. It is now widely recognized that these plastics pose a serious global pollution threat, especially in marine ecosystems (Science 2010, 329, 1185-1188. Science 2015, 347, 768-771). Consequently, there is a pressing demand for new catalytic strategies to efficiently deconstruct these anthropogenic contaminants to minimize and reverse their environmental impact and to allow valuable raw materials to be recovered in an environmentally sustainable manner. In this studentship we will develop integrated and scalable catalytic processes for the efficient recycling of single polymer feedstock of PVC and complex laminated products, such as blister packs. In 2018, PVC made up about 10% of the polymer resin demand and over 12,000 tonnes of blister pack packaging were shipped into the UK for use in medicine delivery and toothbrush packaging. This project aims to address the recycling difficulties associated with PVC and the separation problems associated with mixed composite materials. PVC is problematic as it is readily unzips to yield HCl between 250-400oC producing a highly unsaturated C rich "poly-ene" with low levels of organo-chlorine (0.1%) remaining, problematic for on-processing. The efficiency of Cl removal is further reduced by the use of additives in the packaging, such as dioctylphthalate (Energy & Fuels 2003, 17, 896).Ionic liquids have the capability of dissolving a wide range of materials and we will examine the potential to selectively solubilise the component parts of problematic polymers to allow the downstream processing to value added products more tractable. This will involve the synthesis of ionic liquids which will allow the breakdown of binders as well as potentially reduce the molecular mass of the polymer materials. The development and optimisation of low temperature dehydrochlorination of PVC using ionic liquids, will facilitate the potential recycling of PVC by addition to hydrogen-rich polyolefin mixed polymer streams using slurry and spinning basket reactors, (Garforth, Patent EP 2437886 -2019).Enzymatic deconstruction of unsaturated C rich "poly-ene". Our lab has recently developed automated high-throughput directed evolution workflows to engineer enzymes that efficiently deconstruct plastics with hydrolysable backbones (e.g. PET, unpublished data). These workflows will now be extended to discover and engineer enzymes that efficiently operate on the C-rich poly-ene fraction generated following the dehydrochlorination of PVC. Several families of oxidative enzymes have been discovered which are active towards varying hydrocarbon chain lengths (Sci. Rep. 2014, 4968), which serve as attractive starting points for enzyme engineering to afford commercially viable biocatalysts for PVC deconstruction to allow valuable raw materials to be recovered in an environmentally sustainable fashion.Hydrocracking of unsaturated C rich "poly-ene" comingled with PP initially will be studied under hydrotreating and hydrocracking conditions using a batch reactor. Heterogeneous catalysts established in our lab based on noble metals (Pt, Pd and Ni), or bimetallic sulphides, such as, Co/MoS or Ni/MoS with the acidic supports being alumina or zeolites (Garforth). Traditional ion exchange and impregnation techniques will be supplemented with aerosol-assisted chemical vapour deposition (AACVD) where a single source precursor has been used to produce a range of thin film Mo1-xWxS2 (0<-x<-1) alloys. This inexpensive ambient pressure CVD technique will be extended to Co and Ni. As noted above, the presence of halides, for example in PVC transformations, have the potential to poison the catalysts and this will be examined in detail.The project takes a truly innovative approach to merge the fields of biocatalysis, ionic liquids and heterogeneous bifunctional catalysis, and thus is perfectly aligned to iCAT's priorities.

人造塑料的滥用导致生物圈中不可降解材料的积累。现在人们广泛认识到这些塑料对全球造成严重的污染威胁，特别是在海洋生态系统中（Science 2010, 329, 1185-1188。Science 2015, 347, 768-771）。因此，迫切需要新的催化策略来有效地解构这些人为污染物，以最大限度地减少和扭转其对环境的影响，并允许以环境可持续的方式回收有价值的原材料。在这个学生项目中，我们将开发集成且可扩展的催化工艺，用于有效回收 PVC 单一聚合物原料和复杂的层压产品（例如泡罩包装）。 2018年，PVC约占聚合物树脂需求的10%，超过12,000吨的泡罩包装被运往英国，用于药品输送和牙刷包装。该项目旨在解决与 PVC 相关的回收困难以及与混合复合材料相关的分离问题。 PVC 是有问题的，因为它很容易在 250-400oC 之间解压产生 HCl，产生高度不饱和的富含 C 的“多烯”，且残留有机氯含量较低 (0.1%)，这对加工产生问题。在包装中使用添加剂（例如邻苯二甲酸二辛酯）会进一步降低 Cl 去除效率（Energy & Fuels 2003, 17, 896）。离子液体具有溶解多种材料的能力，我们将研究其潜力选择性地溶解有问题的聚合物的组成部分，使下游加工增值产品更容易处理。这将涉及离子液体的合成，离子液体将分解粘合剂并可能降低聚合物材料的分子量。使用离子液体进行 PVC 低温脱氯化氢的开发和优化，将通过使用浆料和旋转篮式反应器添加到富氢聚烯烃混合聚合物流中，促进 PVC 的潜在回收利用（Garforth，专利 EP 2437886 -2019）。不饱和富含C的“多烯”。我们的实验室最近开发了自动化的高通量定向进化工作流程来设计酶，从而有效地解构具有可水解主链的塑料（例如 PET，未发表的数据）。这些工作流程现在将扩展到发现和设计酶，这些酶可以有效地作用于 PVC 脱氯化氢后产生的富含碳的多烯馏分。已经发现了几个对不同烃链长度具有活性的氧化酶家族（Sci. Rep. 2014, 4968），这为酶工程提供了有吸引力的起点，为 PVC 解构提供商业上可行的生物催化剂，从而使有价值的原材料成为可能。以环境可持续的方式回收。最初将使用间歇式反应器在加氢处理和加氢裂化条件下研究与PP混合的不饱和富C“多烯”的加氢裂化。我们实验室建立的基于贵金属（Pt、Pd 和 Ni）或双金属硫化物（例如 Co/MoS 或 Ni/MoS ）的多相催化剂，酸性载体为氧化铝或沸石（Garforth）。传统的离子交换和浸渍技术将得到气溶胶辅助化学气相沉积 (AACVD) 的补充，其中使用单一源前驱体生产一系列薄膜 Mo1-xWxS2 (0<-x<-1) 合金。这种廉价的环境压力 CVD 技术将扩展到 Co 和 Ni。如上所述，卤化物的存在（例如 PVC 转化中的卤化物）有可能使催化剂中毒，对此将进行详细研究。该项目采用真正创新的方法来合并生物催化、离子液体和多相双功能催化领域，因此与 iCAT 的优先事项完全一致。