Kinetic behaviors of coke gasification with CO2and H2O

Abstract

In the temperature range of 1 173-1 573 K, the constant temperature weight-loss experiment of coke reaction with CO2and H2O was carried out by thermogravimetry. The gasification kinetic behaviors of coke reaction with CO2and H2O were compared and analyzed, and the mechanism of the difference of the kinetic behaviors was discussed. The results show that the internal diffusion condition and interfacial reaction condition of coke gasification in H2O are better than those in CO2, and the difference of diffusion property is greater than that of interface reaction property. The activation energies of internal diffusion and interface reaction of coke gasification in H2O are 80.36 kJ/mol and 36.97 kJ/mol lower than that in CO2, respectively. In H2O, the controlling region of interfacial reaction is larger than that in CO2, and the effect of temperature on controlling region of the interfacial reaction is also greater than that in CO2. The energy required for the chemical adsorption of H2O on the coke surface to form a stable intermediate configuration is 40.22 kJ/mol less than that of CO2, and the energy barrier that needs to cross during the coke gasification in H2O is 29.11 kJ/mol less than that in CO2. The chemisorption capacity of CO2on coke surface is weaker than that of H2O.