Thermal analysis of cyclic carbonation behavior of CaO derived from carbide slag at high temperature

In this work, CaO derived from the carbide slag (CaO?Ccarbide slag) as a kind of typical industrial waste was used to capture CO₂ during the calcination/carbonation cycles. The carbonation kinetics and cyclic carbonation behavior of CaO?Ccarbide slag were investigated in a thermogravimetric analyzer. The chemical reaction activation energy and the product layer diffusion activation energy for carbonation of CaO?Ccarbide slag are 12.46 and 36.83?kJ?mol^?1, respectively, which are significantly less than those for carbonation of CaO derived from the limestone (CaO?Climestone). CaO?Ccarbide slag shows higher carbonation conversion than CaO?Climestone after enough reaction time and at the same number of cycles. Moreover, the calcination temperature and CO₂ concentration in the carbonation atmosphere have important effect on the carbonation behavior of CaO?Ccarbide slag. The BET surface area of CaO?Ccarbide slag is 1.6 times as large as that of CaO?Climestone after 1 cycle and the average pore size of CaO?Ccarbide slag is much smaller. In addition, the carbide slag contains much more Al₂O₃ than most of the limestones. These are reasons why carbide slag as a precursor can retain greater carbonation conversion than limestone in calcination/carbonation cycles.