Ionic liquid biorefining: lignocellulose deconstruction and bio-derived renewable polymers

Lead Research Organisation: Imperial College London
Department Name: Department of Chemical Engineering

Abstract

This project will develop key aspects of an ionic liquid-based biorefinery, by developing optimal strategies for production of pure cellulose for biofuels and high-quality lignin for chemical upgrading. The focus will be on aspects of the deconstruction (pretreatment) process that control the quality and yield of biopolymers from both pure and mixed feedstocks.
Lignocellulosic biomass is the most viable, non-fossil feedstock for large-scale chemical and materials production in an integrated biorefinery, which can only be commercially viable if all components become value-added products. This project will develop efficient routes for the separation of biomass into lignin and carbohydrates, and convert those into renewable materials, demonstrating full pathways from raw material to useful products and biofuels.
A major challenge for biorefineries will be securing a sufficient and reliable supply of sustainably produced feedstock throughout the year. This presents problems for processing due to variation in lignocellulosic composition. While there are various fast-growing bioenergy crops (Miscanthus, switchgrass, willow) and agricultural wastes (wheat straw, corn stover, sugar cane bagasse) available, there are no coherent strategies for processing of mixed feedstocks in an integrated manner. In this project, we will compare IL deconstruction efficiency on several feedstocks of mixed composition, including native (virgin) bioenergy crops, agricultural wastes, and municipal wastes. The goal is to develop a robust, adjustable strategy for dealing with mixed feedstocks.
Our approach. We will separate lignin from carbohydrates as the first step of a biorefinery, building upon our recent success in biomass fractionation with low-cost mineral acid-based IL/water mixtures. To enable this we will determine the key variables controlling both biomass fractionation and recovery of ILs, evaluate their potential for manipulation and exploit these to design ILs for biomass fractionation.
We will use a range of 'protic' ILs, the family used in all IL industrial processes, because their simple acid-base chemistry makes them easy and cheap to prepare and recycle. We recently reported that [HSO4]- ILs with 20% water can quantitatively delignify biomass. The lignin is recovered as a separate fraction in a soluble form, creating a valuable feedstock solution.
We will also assess the impact of these ILs on lignin depolymerization, as this will be a major factor in selecting a suitable solvent system. The suitability of lignin for further valorisation will be an important part of this process - we have targetted several renewable polymers to replace fossil-derived products with lignin- or cellulose-derived alternatives. A project could also be directed in this area, depending on the interests of the researcher.
The quality of both the lignin and cellulose fractions will ultimately drive biorefinery applications. Suitable lignin for chemical catalytic valorisation and cellulose for biofuel production are the essential products of any renewable resource-driven bioeconomy.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509486/1 01/10/2016 30/09/2021
1855916 Studentship EP/N509486/1 20/10/2016 19/04/2020 Amir Al Ghatta
 
Description The research so far have brought important outcomes on different aspects in the production of biochemicals from biomass. The chemical path starts from cellulose as feedstock to arrive to platform chemicals as DFF, FDCA and FFCA used to produce bioplastic, commodites (soaps) and pharmaceutical chemicals . We discovered new chemical concepts in the synthesis of these molecules using ionic liquids as solvents. Today most of the chemical industry relies on oil derivative solvents making the process non carbon neutral. The implementation of ionic liquids in biomass valorisation can give rise to a green process where both the feedstock and the solvent are environmentally friendly .While previously all the literature agreed that the valorisation of biomass in ionic liquids is unfeasible due to product separations, we show that by introducing catalysts in ionic liquids we can produce different molecules that can be easily separated from the solvents. During this research, new catalytic concepts were discovered especially the relationship solvent-catalyst on the selectivity of the reactions particularly we observed that there is a relationship between the chemical proprieties of the catalyst support and the solvent ability to interact with the molecules. Further study is focused to maximise the yield in the production of these molecules by optimising the process parameters.
Exploitation Route The discover of new methodology of product separation form ionic liquid can give an incentive for other researchers in studying different catalysts in these solvents and develop new green routes for biochemicals that can replace oil derivate products, reducing CO2 emissions and the depletion of oil reserves. Further study on these fields can give important contributions on catalysis mechanism and solvent recyclability.
Sectors Chemicals,Environment,Other

URL https://pubs.acs.org/doi/abs/10.1021/acssuschemeng.9b06691
 
Description The award permitted to expand the study towards biosurfactants , which will result are very promising and used to submit a patent.
First Year Of Impact 2020
Sector Chemicals