Gas evolution kinetics of two coal samples during rapid pyrolysis

Quantitative gas evolution kinetics of coal primary pyrolysis at high heating rates is critical for developing predictive coal pyrolysis models. This study aims to investigate the gaseous species evolution kinetics of a low rank coal and a subbituminous coal during pyrolysis at a heating rate of 1000 °C s− 1 and pressures up to 50 bar using a wire mesh reactor. The main gaseous species, including H2, CO, CO2, and light hydrocarbons CH4, C2H2, C2H4, C2H6, C3H6, C3H8, were quantified using high sensitivity gas chromatography. It was found that the yields of gaseous species increased with increasing pyrolysis temperature up to 1100 °C. The low rank coal generated more CO and CO2 than the subbituminous coal under similar pyrolysis conditions. Pyrolysis of the low rank coal at 50 bar produced more gas than at atmospheric pressure, especially CO2, indicating that the tar precursor had undergone thermal cracking during pyrolysis at the elevated pressure.