Characterization of pilot-scale dilute acid pretreatment performance using deacetylated corn stover

Area of Science:

• Biomass Pretreatment
• Biomass Conversion
• Renewable Energy

Background:

• Dilute acid pretreatment is effective for lignocellulosic biomass deconstruction.
• High acid concentrations (1-4%) have historically limited cost-effectiveness and scalability.
• Reducing acid loading can decrease chemical costs and reactor material requirements.

Purpose of the Study:

• To optimize dilute acid pretreatment of deacetylated corn stover at low acid loadings.
• To identify optimal reaction conditions for maximizing sugar yields.
• To evaluate the feasibility of low-acid pretreatment in pilot-scale operations.

Main Methods:

• Conducted over 25 pilot-scale experiments in a 1-ton/day horizontal reactor.
• Varied reactor temperatures (150-170°C) and residence times (10-20 min).
• Utilized low sulfuric acid concentrations (0.15-0.30% w/w).

Main Results:

• Achieved 73.5% ± 1.5% total xylose yield from pretreatment.
• Demonstrated >97% xylan component balance closure across multiple runs.
• Obtained 77% feedstock reactivity after enzymatic hydrolysis.

Conclusions:

• Identified an optimal low-acid pretreatment condition for deacetylated corn stover.
• Successfully integrated this condition into pilot-scale cellulosic ethanol production.
• Highlighted challenges for continuous systems, including char formation and feedstock feeding.