A study on factors influencing CO2 adsorption by coal

The effects of moisture, pH value, and coal rank on adsorption of CO2 by coal were studied using a self-made small sample coal adsorption device. Coal of different ranks was dried, acidified, and alkalized. CO2 gas (16%) was injected into the device at normal temperature and pressure. The results showed that the moisture and pH value in the environment and the coal rank had an influence on the CO2 adsorption capacity of coal. The saturation adsorption capacity of CO2 of acid-treated coal and alkaline-treated coal increased by 3.342%–4.255% and 0.808%–2.22%, respectively, compared to dry coal. The saturated adsorption capacity of CO2 of untreated coal was reduced by 2.176%–2.521% compared to the dry sample. According to experimental data, the existence of moisture inhibited the adsorption of CO2 by coal, and the increase or decrease in the pH value promotes the adsorption of CO2 by coal. The decrease in the pH value had the greatest influence on the adsorption of CO2 by coal. The higher coal rank resulted in the increased saturated adsorption capacity of CO2.