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

In order to deeply understand the influence of CaO on the gasification reaction of carbon and CO2, the nonisothermal 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(alpha) = 3(1-alpha)2/3 to f(alpha) = 2(1-alpha)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.

Automated summary

The positive catalytic effect of CaO on the gasification reaction of carbon and CO2 was investigated. It was found that CaO can decrease the start temperature, end temperature, and the temperature with the maximum reaction rate of carbon-CO2 gasification. The addition of CaO also reduces the activation energy of the reaction, making it easier to occur. Furthermore, CaO modifies the structure and electrical properties of the carbon matrix, leading to increased reaction activity.