Temperature-dependent phase behaviour of tetrahydrofuran–water alters solubilization of xylan to improve co-production of furfurals from lignocellulosic biomass

Journal Article · Tue Mar 06 00:00:00 EST 2018 · Green Chemistry

DOI:https://doi.org/10.1039/C7GC03608F· OSTI ID:1435286

Smith, Micholas Dean  ^[1]; Cai, Charles M.  ^[2]; Cheng, Xiaolin ^[3]; Petridis, Loukas ^[1]; Smith, Jeremy C. ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Univ. of California, Riverside, CA (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Xylose, Xylan, Hemicellulose, CELF, THF, Co-solvent, Pretreatment, Biomass ABSTRACT: Xylan is an important polysaccharide found in the hemicellulose fraction of lignocellulosic biomass that can be hydrolysed to xylose and further dehydrated to the furfural, an important renewable platform fuel precursor. Here, pairing molecular simulation and experimental evidences, we reveal how the unique temperature-dependent phase behaviour of water-tetrahydrofuran (THF) co-solvent can delay xylan solubilization to synergistically improve catalytic co-processing of biomass to furfural and 5-HMF. Our results indicate, based on polymer correlations between polymer conformational behaviour and solvent quality, that both co-solvent and aqueous environments serve as ‘good’ solvents for xylan. Interestingly, the simulations also revealed that unlike other cell-wall components (i.e., lignin and cellulose), the make-up of the solvation shell of xylan in THF-water is dependent on the temperature-phase behaviour. At temperatures between 333K and 418K, THF and water become immiscible, and THF is evacuated from the solvation shell of xylan, while above and below this temperature range, THF and water are both present in the polysaccharide’s solvation shell. This suggested that the solubilization of xylan in THF-water may be similar to aqueous-only solutions at temperatures between 333K and 418K and different outside this range. Experimental reactions on beachwood xylan corroborate this hypothesis by demonstrating 2-fold reduction of xylan solubilization in THF-water within a miscible temperature regime (445K) and unchanged solubilization within an immiscible regime (400K). Translating this phase-dependent behaviour to processing of maple wood chips, we demonstrate how the weaker xylan solvation in THF-water under miscible conditions can delay furfural production from xylose, allowing 5-HMF production from cellulose to “catch-up” such that their high yield production from biomass can be synergized in a single pot reaction.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Univ. of California, Riverside, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-00OR22725; FWP ERKP752; EE0007006; AC02-05CH11231
• OSTI ID: 1435286
• Alternate ID(s): OSTI ID: 1434087; OSTI ID: 1595233
• Journal Information: Green Chemistry, Vol. 20, Issue 7; ISSN 1463-9262
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

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