Developing and understanding lignin dissolving ionic liquids for sustainable carbon fibre production from lignin

开发和了解木质素溶解离子液体，用于从木质素可持续生产碳纤维

• 批准号: 2376398
• 金额: --
• 依托单位: Imperial College London
• 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: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2376398
• 关键词: Developing; understanding; lignin; dissolving; ionic

Ionic liquids (ILs) are increasingly popular alternative solvents for many processes, due to their tuneable physicochemical properties.1 They are utilised in catalysis,2 electrodeposition3,4 and biomass valorisation, in particular, in the high yielding dissolution and recovery of lignin from wood biomass. In order to enable a larger numbers of viable industrial processes utilising ionic liquids, both cost and safety need to be assessed for each ionic liquid that shows promising performance. While certain ionic liquids are known to be able to withstand high-temperature processes, resulting in high recyclability in principle, they are often expensive to synthesise. A number of ILs have been shown to have high solubility for lignin, with water being an inexpensive antisolvent, which makes these ILs interesting solvents for isolating lignin from biomass and for use in lignin purification and in fibre formation. Recently reported protic hydrogen sulfate ionic liquids have shown particular promising potential as industrial candidates for wood fractionation, with bulk solvent cost as low as $1.87 kg-1.6,7 However, the thermal properties of these ILs are poorly understood. Hence, one aim of this project is to produce comprehensive kinetic and thermal data regarding the stability and decomposition mechanisms of lignin dissolving low-cost ILs, and the vapour phase composition upon degradation of these ionic liquids will be studied. A second aim of the project is to produce lignin dissolving ionic liquids that display the anisotropic behaviour of liquid crystals phases at temperatures of interest. It is the hypothesis that the unsatisfactory performance of lignin based carbon fibres to date is the disordered arrangement of the lignin polymers in the precursor fibres, which appears to limit the formation of ordered graphitic domains during carbonisation and hence the strength and stiffness of resulting carbon fibres. Using isotropic hydrogen sulfate ionic liquids as well as the novel ionic liquid crystals, the project will investigate whether either type of ionic liquid can help produce more ordered precursor fibres, which should result in stronger, cheaper, more sustainable carbon fibres. The ILs will be used to modify the lignin either as part of the extraction or as a post-extraction purification step. As a third aim, to enable fibre production, the project will develop a heated microextruder, which can be used for melt-spinning lignin fibres or for hot wet-sinning of lignin fibres at a very small (<1 g) scale, with the heat helping to reduce the viscosity of the spinning dope, which increases polymer loading in the ionic liquid dopes and hence improving processing economics.

离子液体（IL）由于其可调节的物理化学性质，越来越成为许多工艺的替代溶剂。1它们用于催化、2电沉积3，4和生物质增值，特别是用于从木材生物质中高产溶解和回收木质素。为了使更多的可行的工业过程利用离子液体，成本和安全性都需要评估每种离子液体，显示有前途的性能。虽然已知某些离子液体能够承受高温过程，原则上导致高可再循环性，但它们的合成通常是昂贵的。许多IL已经显示出对木质素具有高溶解度，水是廉价的抗溶剂，这使得这些IL成为用于从生物质中分离木质素以及用于木质素纯化和纤维形成的令人感兴趣的溶剂。最近报道的质子硫酸氢盐离子液体已经显示出作为木材分馏的工业候选物的特别有前途的潜力，其中本体溶剂成本低至$1.87 kg-1.6，7。然而，这些离子液体的热性质知之甚少。因此，该项目的一个目的是产生关于木质素溶解低成本离子液体的稳定性和分解机制的综合动力学和热数据，并将研究这些离子液体降解后的气相组成。该项目的第二个目的是生产溶解木质素的离子液体，其在感兴趣的温度下显示液晶相的各向异性行为。假设迄今为止木质素基碳纤维的不令人满意的性能是木质素聚合物在前体纤维中的无序排列，这似乎限制了碳化过程中有序石墨域的形成，因此限制了所得碳纤维的强度和刚度。利用各向同性的硫酸氢离子液体以及新型离子液体晶体，该项目将研究两种离子液体是否可以帮助生产更有序的前体纤维，这将导致更强，更便宜，更可持续的碳纤维。IL将用于改性木质素，作为提取的一部分或作为提取后纯化步骤。作为第三个目标，为了实现纤维生产，该项目将开发一种加热的微型挤出机，该挤出机可用于熔融纺丝木质素纤维或用于非常小（<1 g）规模的木质素纤维的热湿烧结，热量有助于降低纺丝原液的粘度，这增加了离子液体原液中的聚合物负载，从而提高了加工经济性。