Porous biochar production from pyrolysis of corn straw in a microwave heated reactor

Abstract

Conversion of corn straw into biochar by pyrolysis was considered as an environmentally friendly and efficient method for biomass sources because porous biochar has excellent properties and wide applications. Porous biochar production from corn straw in a microwave heated reactor was the main purpose of this study. The yields and microstructures of biochar produced at different pyrolysis temperatures (500, 600, 700, 800, and 900 °C), microwave powers (600, 650, 700, 750, and 800 W), and pyrolysis times (30, 40, 50, 60, and 70 min) were studied. The results showed that biochar yield ranged from 44.69 to 59.90 wt% with the changes of reaction conditions. Biochar with the nanoscale pores was first obtained at pyrolysis temperature of 800 °C, microwave power of 600 W, and pyrolysis time of 30 min, indicating that corn straw biochar had the potential to produce nanoscale pores. This study also quantitatively described the relationship between microstructure and productivity of corn straw biochar at different experimental conditions (pyrolysis temperature, microwave power, pyrolysis time), which can provide guidance for the reuse of corn straw and the production of porous biochar.