CO2 Adsorption Properties of Amine-Modified Zeolites Synthesized Using Different Types of Solid Waste

Abstract

In this study, organic amines were used to modify zeolite NaA and analcime synthesized using fly ash and iron tailing slag as raw materials, respectively, and the adsorption properties of the modified zeolites toward CO2 were determined. We found that when tetraethylenepentamine (TEPA) was used, the modified zeolite NaA and analcime had the highest nitrogen content. The adsorption capacity of the modified zeolite NaA for CO2 was 4.02 mmol/g and that of the modified analcime was 1.16 mmol/g when the adsorption temperature was 70 °C and the CO2 flow rate was 50 mL/min. According to the adsorption isotherm, kinetic, and thermodynamic model fitting, the adsorption surface of the modified zeolite was not uniform, and the CO2 adsorption of the modified zeolites was classified as chemical adsorption. In a mixed atmosphere of 15% CO2/85% N2, the dynamic selection coefficients of the modified zeolite NaA and analcime for CO2 were 3.8942 and 2.9509, respectively; thus, the two amine-modified zeolites had good selectivity for CO2. After five cycles, the adsorption efficiencies of the modified zeolite NaA and modified analcime for CO2 were 92.8% and 89%, respectively. Therefore, the two amine-modified zeolites showed good recycling performance.