Effect of carbonization temperature on CO₂ adsorption behavior of activated coal char

Nowadays, the increase of CO₂ concentration caused by the utilization of traditional fossil fuels has a negative impact on the environment and human health. Therefore, there is an urgent need to explore effective measures to control CO₂ emission. In this work, activated coal char for CO₂ capture was prepared with different carbonization temperatures by two-step method with KOH as the activator. The effects of carbonization temperature and adsorption temperature on the CO₂ adsorption performance of activated coal char were investigated. Elemental analysis, BET, XPS and SEM analysis of the activated coal char were performed. The results showed that the microporous structure has an important influence on the adsorption performance of activated coal char. With the increase of carbonization temperature, the microporous volume increases first following by a decrease and the amount of CO₂ adsorption also shares the same trend. For the adsorption temperature, as the adsorption temperature rises, the CO₂ adsorption capacity of activated coal char decreases. The maximum CO₂ adsorption capacity of 4.8 mmol/g was achieved at optimal conditions of carbonization temperature 600 °C, adsorption temperature 0 °C and pressure 1 bar. In addition, the activated coal char with a carbonization temperature of 600 °C also shows good selectivity for CO₂ over N₂, which indicated its prospects in the practical CO₂ capture applications.