Study on CO2 gasification reactivity and physical characteristics of biomass, petroleum coke and coal chars

•CO2 gasification kinetics with biomass, coke and coal chars were measured in TGA.•Physical structures and chemical components of different chars were examined.•The crystalline structure is an key factor to evaluate reactivities of various chars.•The difference in diffusion effects among gasification with various chars is obvious.•The difference is attributed to intrinsic reactivity and physical property of chars. Gasification reactivities of six different carbonaceous material chars with CO2 were determined by a Thermogravimetric Analyzer (TGA). Gasification reactivities of biomass chars are higher than those of coke and coal chars. In addition, physical structures and chemical components of these chars were systematically tested. It is found that the crystalline structure is an important factor to evaluate gasification reactivities of different chars and the crystalline structures of biomass chars are less order than those of coke and coal chars. Moreover, initial gasification rates of these chars were measured at high temperatures and with relatively large particle sizes. The method of calculating the effectiveness factor η was used to quantify the effect of pore diffusion on gasification. The results show that differences in pore diffusion effects among gasification with various chars are prominent and can be attributed to different intrinsic gasification reactivities and physical characteristics of different chars.