Effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis

• About 530 °C was reached within 10 min at a microwave power level of 500 W.
• Gas yield increased with increasing microwave power level.
• A high correlation between hemicellulose content and either H2 or CO2 yield.
• A high correlation between cellulose content and either CH4 or CO yield.
• Empirical equations depict contribution of lignocellulosic content to gas yield.

Agricultural residues are abundant resources to produce renewable energy and valuable chemicals. This study focused on the effects of lignocellulosic composition and microwave power level on the gaseous product of microwave pyrolysis of agricultural residues. When agricultural residues were under microwave radiation within 10 min, the maximum temperatures of approximately 320, 420, and 530 °C were achieved at the microwave power levels of 300, 400, and 500 W, respectively. Gas yield increased with increasing microwave power level, whereas solid and liquid yields decreased. Besides, gaseous products with higher H2 content and higher calorific values can be obtained at higher microwave power levels. In addition to microwave power level, lignocellulosic composition was also an important factor. H2 and CO2 yields increased with increasing hemicellulose content, whereas CH4 and CO yields increased with increasing cellulose content. Four empirical equations were derived to present the contributions of lignocellulosic materials to the yields of gaseous components.