One of the key challenges in biorefining is the initial separation or deconstruction of lignocellulosic feedstock into separate components. Ionic liquids (organic salts) offer unique advantages in this area, due to their unusual thermochemical properties. However, there are serious concerns about the economic viability of their use due to the very high cost of most ionic liquids (&gt; €50/kg) [2]. We have overcome this by redesigning the IL based deconstruction process to use low-cost, acidic ILs for lignin dissolution rather than cellulose dissolution [1], yielding filterable cellulose and a dissolved lignin for precipitation or conversion to high-value chemicals. We have found that processability of the cellulose is high and lignin recoveries near quantitative. We use a range of ‘protic’ ILs, the family typically used in IL industrial processes, because their simple acid-base chemistry results in a simple and cheap synthesis, with a cost (&lt; €1/kg) similar to common organic solvents such as acetone or toluene [3]. This presentation will discuss pretreatment conditions, saccharification yields, pulp quality, lignin characterisation, ionic liquid interactions with the biopolymers, and manufacturing approaches. Studies involving model compounds for lignin and cellulose have been used in an effort to understand the molecular-scale chemistry and mechanistic events underpinning the observed solution chemistry. This will eventually enable us to identify target compounds and synthesis routes for the valorization of our biomass feedstocks. The results from this study demonstrate that the ILs maintain solvent stability under long-term processing conditions, that they can be recovered and continue to exhibit very good cellulose lignin fractionation after multiple reuses. These properties highlight that the ILs have the flexibility to be useful for a variety of downstream chemical processing techniques, and for use in other applications as well. References [1] A. George, A. Brandt, S. Singh, B.A. Simmons, J.P. Hallett, Green Chem., 2015, in press (DOI: 10.1039/C4GC01208A). [2] D. Klein-Marcuschamer, B.A. Simmons, H.W. Blanch, Biofuels, Bioprod. Biorefin., 2011, 5, 562–56. [3] L. Chen, M. Sharifzadeh, N. Mac Dowell, T. Welton, N. Shah, J.P. Hallett, Green Chem., 2014, 16, 3098-3106.

Low-cost ionic liquids for lignocellulose deconstruction

251st National Meeting (2016)

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