Enhancement of biomass conversion in catalytic fast pyrolysis by microwave-assisted formic acid pretreatment

• Microwave-assisted formic acid (MA-FA) pretreatment can rapidly destruct biomass structure.
• MA-FA pretreatment selectively removes hemicellulose and lignin components of biomass.
• MA-FA pretreatment increases the valuable aromatic products in CFP of biomass.
• MA-FA pretreatment decreases the undesired coke formation in CFP of biomass.

This study investigated microwave-assisted formic acid (MW-FA) pretreatment as a possible way to improve aromatic production from catalytic fast pyrolysis (CFP) of lignocellulosic biomass. Results showed that short duration of MW-FA pretreatment (5–10 min) could effectively disrupt the recalcitrant structure of beech wood and selectively remove its hemicellulose and lignin components. This increased the accessibility of cellulose component of biomass to subsequent thermal conversion in CFP. Consequently, the MW-FA pretreated beech wood produced 14.0–28.3% higher yields (26.4–29.8 C%) for valuable aromatic products in CFP than the untreated control (23.2 C%). In addition, the yields of undesired solid residue (char/coke) decreased from 33.1 C% for the untreated control to 28.6–29.8 C% for the MW-FA pretreated samples. These results demonstrate that MW-FA pretreatment can provide an effective way to improve the product distribution from CFP of lignocellulose.