The effect of CO on coal-biomass co-gasification with CO2

•Coal-biomass blended char was gasified with CO2 in the presence of CO.•Inhibition effect of CO on char-CO2 gasification was studied.•Langmuir-Hinshelwood (L-H) equation was used to describe the CO inhibition effect.•Random pore model was used to interpret the carbon conversion data.•L-H kinetic parameters were obtained and expressed in an Arrhenius equation form.

In this study, co-gasification of coal and biomass chars with CO2 in the presence of CO was investigated at three different temperatures: 850, 875, and 900 °C. A coal-biomass (bituminous-pineapple sawdust) mixture with a mass ratio of 1:1 was used for devolatilization and co-gasification. Random pore model was employed to determine the kinetic coefficient from experimentally obtained carbon conversion data. The Langmuir-Hinshelwood (L-H) equation, which has been widely used in literatures to describe the relationship between kinetic coefficient of the gasification and partial pressures of reacting gases, effectively represented the inhibition effect of CO on char-CO2 gasification. The kinetic parameters of the L-H equation were acquired from the experimental data. The activation energy (E) and pre-exponential factor (A) of each kinetic parameter of L-H equation were obtained using the Arrhenius equation. CO inhibition effect was more powerful in the Char-CO2 co-gasification of the mixed sample compared to those in the unmixed samples. Further, for each sample, the inhibition effect was stronger at lower temperature owing to a smaller number of active sites.