2024 AIChE Annual Meeting

(687d) High Efficient Organosolve Pretreatment of Lignocellulose for Biorefinery System Construction

Author

Zhuang, X. - Presenter, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences
Pretreatment is the basis to realize the bio-refining process of preparing fuel and chemicals from lignocellulosic biomass, which determines the direction and efficiency of refining. Organic solvent pretreatment has become one of the hot spots in pretreatment research because of its high efficiency of component disassembly, high retention of decomposed cellulose components and high purity of recycled lignin components.

Phenoxyethanol is considered a green, non-toxic organic solvent, with a good ability to dissolve lignin. Due to its water immiscible, we constructed a biphasic phenoxyethanol/water system for rice straw pretreatment1,2. After pretreatment, the residue is mainly cellulose, meanwhile, five-carbon sugars decomposed from hemicellulose are dissolved in aqueous phase and lignin is distributed in organic phase. The biphasic pretreatment shows outstanding advantages and broad application prospects in the biorefinery of lignocellulosic substrates due to the separation process for products in the solvent phase, and the reutilization of solvents. The phenoxyethanol/water biphasic system could also be performed under alkaline conditions3. However, a small amount of water is still dissolved in the organic solvent that makes up biphasic system, and few studies have focused on the pretreatment performance of this monophasic system.

Herein, the effects of water content in phenoxyethanol solution on fractionated components and enhanced enzymatic hydrolysis of poplar pretreatment under acid condition was investigated. With the decrease of water content, the solvent system changed from biphasic to monophasic. Compared to biphasic system, the monophasic system overcame the mass transfer hindrance and showed better delignification and hemicellulose removal during the pretreatments. Impressively, a one-step pretreatment of poplar below 130°C in monophasic system with lower water content resulted in almost complete removal of lignin and hemicellulose, yielding a residue with ~90% cellulose content, and with ~90% enzymatic digestion. Overall, water was involved not only in changing the phase state of the system, but also in changing the lignin solubilization properties of the solution, determining the strength of the reaction and supporting the hydrolysis of the components. Our findings are useful for organosolv pretreatment and bio-refinings.

References:

  1. Screening Solvents Based on Hansen Solubility Parameter Theory To Depolymerize Lignocellulosic Biomass Efficiently under Low Temperature. ACS Sustainable Chem. Eng. 2019, 7, 8678
  2. Biphasic fractionation of rice straw under mild condition in acidified 2-phenoxyethanol/water system. Industrial Crops & Products. 2020, 145, 112091
  3. A Novel Recyclable Alkaline Biphasic 2‑Phenoxyethanol/Water System for Rice Straw Biorefinery under Mild Conditions. ACS Sustainable Chem. Eng. 2020, 8, 7649
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