Explorations on Thermodynamic and Kinetic Performances of Various Cationic Exchange Durations for Synthetic Clinoptilolite |
| |
Authors: | Keling Wang Bingying Jia Yehong Li Jihong Sun Xia Wu |
| |
Institution: | Beijing Key Laboratory for Green Catalysis and Separation, Department of Environmental and Chemical Engineering, Beijing University of Technology, Beijing 100124, China; (K.W.); (B.J.); (Y.L.) |
| |
Abstract: | Various cation–exchanged clinoptilolites (M–CPs, M = Li+, Cs+, Ca2+, Sr2+) were prepared, and their exchanged thermodynamic (and kinetic) properties and adsorption performances for CH4, N2, and CO2 were investigated. The results demonstrated that the relative crystallinity of M–CPS decreased with the increase of exchange times. Their chemisorbed water weight loss gradually increased with the increasing exchange times, except that of Cs–x–CP. The Δr values of exchange process of Li+, Cs+, Ca2+, or Sr2 presented the increased trend with the enhanced exchange times, but they decreased as the temperature increased. The negative Δr values and the positive Δr and Δr values suggested that the exchanged procedure belonged to spontaneous, endothermic, and entropy-increasing behaviors; their kinetic performances followed a pseudo–second–order model. However, the calculated Ea values of exchange process showed the increased tendencies with the enhanced exchange times, indicating that the exchange process became more difficult. Finally, the preliminary adsorption results indicated that the maximum adsorption amount at 273 K and 1 bar was 0.51 mmol/g of CH4 and 0.38 mmol/g of N2 by (Na, K)–CP, and 2.32 mmol/g of CO2 by Li–6–CP. |
| |
Keywords: | clinoptilolite ion exchange thermodynamic kinetics gas separation |
|
|