Beijing Key Laboratory for Green Catalysis and Separation, Department of Environmental and Chemical Engineering, Beijing University of Technology, Beijing 100124, China.
Molecules. 2022 Apr 18;27(8):2597. doi: 10.3390/molecules27082597.
Various cation-exchanged clinoptilolites (M-CPs, M = Li, Cs, Ca, Sr) were prepared, and their exchanged thermodynamic (and kinetic) properties and adsorption performances for CH, N, and CO were investigated. The results demonstrated that the relative crystallinity of M-CP 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 ΔGmθ values of exchange process of Li, Cs, Ca, or Sr presented the increased trend with the enhanced exchange times, but they decreased as the temperature increased. The negative ΔGmθ values and the positive ΔHmθ and ΔSmθ 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 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 CH and 0.38 mmol/g of N by (Na, K)-CP, and 2.32 mmol/g of CO by Li-6-CP.
制备了不同阳离子交换的斜发沸石（M-CPs，M=Li、Cs、Ca、Sr），研究了它们的交换热力学（和动力学）性质以及对 CH、N 和 CO 的吸附性能。结果表明，M-CP 的相对结晶度随交换次数的增加而降低。除 Cs-x-CP 外，它们的化学结合水失重逐渐随交换次数的增加而增加。Li、Cs、Ca 或 Sr 的交换过程的ΔGmθ 值随交换次数的增加呈现出增加的趋势，但随着温度的升高而降低。负的ΔGmθ 值和正的ΔHmθ 和ΔSmθ 值表明交换过程属于自发、吸热和熵增加的行为；它们的动力学性能遵循拟二级模型。然而，交换过程的计算 值随交换次数的增加呈现出增加的趋势，表明交换过程变得更加困难。最后，初步的吸附结果表明，在 273 K 和 1 bar 下，（Na，K）-CP 对 CH 的最大吸附量为 0.51 mmol/g，对 N 的最大吸附量为 0.38 mmol/g，Li-6-CP 对 CO 的最大吸附量为 2.32 mmol/g。
