Influence mechanism of CaO on gasification characteristics and kinetic behaviors of carbon-CO2 reaction

•The carbon-CO2 gasification characteristics under different w(CaO) were studied.•The effect of CaO on the kinetic behavior of carbon-CO2 gasification was analyzed.•CaO has a positive catalytic effect on the gasification reaction of carbon-CO2.•After CaO adsorption, the carbon matrix stability decreases and activity increases. In order to deeply understand the influence of CaO on the gasification reaction of carbon and CO2, the non-isothermal gasification processes of carbon-CO2 at different heating rates under different w(CaO) were studied by thermogravimetric analysis, and the influence law and mechanism of CaO on the reaction characteristic parameters and kinetic processes were analyzed. The results show that, CaO has a positive catalytic effect on the gasification reaction of carbon and CO2. The start temperature, end temperature and the temperature with the maximum reaction rate of carbon-CO2 gasification gradually decrease with increasing w(CaO) at each heating rate. With the increase of w(CaO), the activation energy decreases as a whole, w(CaO) increases from 0% to 6%, which reduces the reaction activation energy by 16.18 kJ/mol, and the reaction becomes easier. The mechanism function after adding CaO is determined by f(α) = 3(1-α)2/3 to f(α) = 2(1-α)1/2. The adsorption of CaO on the surface of carbon matrix makes the C–C bond length between active C atoms longer, the electronegativity increases, the reaction activity increases, the energy of carbon matrix increases by 76.965 kJ/mol, and the structural stability decreases, which are conducive to the occurrence of carbon-CO2 gasification reaction.