Evaluation of CO2 adsorption capacity of solid sorbents

Abstract

The CO2 adsorption capacity of the low-cost solid sorbents of waste tire char (TC) and chicken waste char (CW) was compared with commercial active carbon (AC) and 5 A zeolite (ZA) using thermogravimetric analysis (TG), pressurized TG, and differential scanning calorimetry (DSC). The sorbents were degassed in a TG up to 150 °C to release all gases on the surface of the sample, then cooled down to the designed temperature for adsorption. TG results indicated that the CO2 adsorption capacity of TC was higher than that of CW, but lower than those of AC and ZA. The maximum adsorption rate of TC at 50 °C was 0.61% min−1, lower than that of AC, but higher than that of CW, 0.44% min−1. The maximum adsorption rate of ZA at 50 °C was 3.1% min−1. When the pressure was over 4 bar, the adsorption rate of ZA was lower than that of TC and AC. At 30 bar, the total CO2 uptake of TC was 20 wt%, higher than that of CW and ZA but lower than that of AC. The temperature, nitrogen concentration, and water content also influenced the CO2 adsorption capacity of sorbents to some extent. DSC results showed that adsorption was an exothermic process. The heat of CO2 adsorption per mole of CO2 of TC at 50 °C was 24 kJ mol−1 while the ZA had the largest heat of adsorption at 38 kJ mol−1. Comparing the characteristics of TC and CW, TC may be a promising sorbent for removal of CO2.