Impact of high biomass loading on ionic liquid pretreatment

Area of Science:

• Biomass Pretreatment
• Biochemical Engineering
• Renewable Energy

Background:

• Ionic liquid (IL) pretreatment offers high sugar yields for biomass conversion.
• Improving process economics necessitates higher biomass loading during IL pretreatment.
• Understanding the impact of high biomass loading on IL pretreatment is crucial for industrial application.

Purpose of the Study:

• To investigate the effect of high biomass loading (up to 50 wt%) of switchgrass on IL pretreatment.
• To analyze changes in viscosity, cellulose crystallinity, chemical composition, saccharification kinetics, and sugar yield.
• To determine optimal biomass loading for efficient IL pretreatment.

Main Methods:

• Pretreatment of switchgrass using ionic liquids at varying biomass loadings (3-50 wt%).
• Rheological analysis to assess slurry viscosity and behavior (shear thinning, elastic properties).
• Characterization of pretreated solids (glucan, lignin, hemicellulose content, cellulose crystallinity).
• Enzymatic saccharification to determine sugar yields.

Main Results:

• Switchgrass/IL slurries exhibited frequency-dependent shear thinning behavior.
• A transition from viscous to elastic behavior was observed with increasing biomass loading.
• Increased biomass loading led to decreased relative glucan content and increased lignin/hemicellulose.
• IL pretreatment transformed cellulose crystallinity from I to II, and to an amorphous structure at 40-50 wt% loading.

Conclusions:

• IL pretreatment effectively reduces switchgrass recalcitrance at loadings up to 50 wt%.
• High biomass loadings increase shear viscosity but exhibit shear thinning, reducing overall viscosity.
• Rheological properties and sugar yields suggest 10-50 wt% are desirable loading ranges for IL pretreatment.