Novel improvement of CO2 adsorption capacity and selectivity by ethylenediamine-modified nano zeolite

Abstract

In this study, nano zeolite (NZ) was modified with ethylenediamine (EDA) to improve the CO2 adsorption–desorption properties. The CO2 adsorption capacity of NZ-EDA increased as the temperature was increased from 20°C to 70°C, but then decreased as the temperature was further increased from 70 °C to 100°C. The CO2 adsorption capacity of NZ-EDA was 7.48mmol/g, which is 2.6-fold more than that by NZ. The mechanism of CO2 adsorption onto NZ is entirely physical interaction. With NZ-EDA, however, chemical interaction between CO2 and NZ-EDA becomes the key adsorption mechanism. The adsorption selectivity of CO2 over N2 by NZ-EDA was influenced by temperature and peaked at 56.01 at 50°C. The cyclic adsorption and desorption of CO2 showed that the adsorbed CO2 could be desorbed from the surface of NZ at 60°C and NZ-EDA at 85°C. The adsorption–desorption percentages of NZ and NZ-EDA remained above 80% even after 15 cycles. This stability of CO2 adsorption–desorption characteristics after repeated cycling indicates that NZ-EDA can be a cost-effective sorbent for CO2 capture.