Production of Furfural from Process-Relevant Biomass-Derived Pentoses in a Biphasic Reaction System

Furfural is an important fuel precursor which can be converted to hydrocarbon fuels and fuel intermediates. In this work, the production of furfural by dehydration of process-relevant pentose rich corn stover hydrolyzate using a biphasic batch reaction system has been investigated. Methyl isobutyl ketone (MIBK) and toluene have been used to extract furfural and enhance overall furfural yield by limiting its degradation to humins. The effects of reaction time, temperature, and acid concentration (H₂SO₄) on pentose conversion and furfural yield were investigated. For the dehydration of 8 wt % pentose-rich corn stover hydrolyzate under optimum reaction conditions, 0.05 M H₂SO₄, 170 °C for 20 min with MIBK as the solvent, complete conversion of xylose (98–100%) and a furfural yield of 80% were obtained. Under these same conditions, except with toluene as the solvent, the furfural yield was 77%. Additionally, dehydration of process-relevant pentose rich corn stover hydrolyzate using solid acid ion-exchange resins under optimum reaction conditions has shown that Purolite CT275 is as effective as H₂SO₄ for obtaining furfural yields approaching 80% using a biphasic batch reaction system. This work has demonstrated that a biphasic reaction system can be used to process biomass-derived pentose rich sugar hydrolyzates to furfural in yields approaching 80%

3D Electron Tomography of Pretreated Biomass Informs Atomic Modeling of Cellulose Microfibrils

Fundamental insights into the macromolecular architecture of plant cell walls will elucidate new structure–property relationships and facilitate optimization of catalytic processes that produce fuels and chemicals from biomass. Here we introduce computational methodology to extract nanoscale geometry of cellulose microfibrils within thermochemically treated biomass directly from electron tomographic data sets. We quantitatively compare the cell wall nanostructure in corn stover following two leading pretreatment strategies: dilute acid with iron sulfate co-catalyst and ammonia fiber expansion (AFEX). Computational analysis of the tomographic data is used to extract mathematical descriptions for longitudinal axes of cellulose microfibrils from which we calculate their nanoscale curvature. These nanostructural measurements are used to inform the construction of atomistic models that exhibit features of cellulose within real, process-relevant biomass. By computational evaluation of these atomic models, we propose relationships between the crystal structure of cellulose Iβ and the nanoscale geometry of cellulose microfibrils