无机材料学报, 2020, 35 (4): 469, 网络出版: 2021-03-01
混合超微孔材料中CO2/N2吸附与分离的理论研究
巨正则蒙特卡洛 混合超微孔材料 吸附 分离 grand-canonical Monte Carlo hybrid microporous materials adsorption separation
摘要
碳捕获与封存技术是一种具有前景的CO2减排策略。本工作采用巨正则蒙特卡洛模拟研究了温度为298 K、压强在0~5 kPa范围内三种混合超微孔材料SIFSIX-X-Cu(以SiF62-排列, Cu为金属中心, X=2, 3, O)中CO2/N2吸附与分离的行为。结果显示, 相比于SIFSIX-2-Cu, SIFSIX-3-Cu和SIFSIX-O-Cu中CO2在0.5 kPa就达到吸附饱和, 且在1 kPa下的吸附量分别达到了2.70与2.39 mmol·g -1。CO2/N2混合气体中CO2的吸附量几乎没有下降。SIFSIX-3-Cu和SIFSIX-O-Cu具有接近于CO2分子动力学直径的孔径, 对CO2亲和力较大, 吸附热分别达到了59和66 kJ·mol -1。密度泛函理论分析发现, 在两种结构中每个孔隙只吸附一个CO2分子, 且几乎处于孔道的中心。本工作为低压下吸附与分离CO2的混合超微孔材料的开发提供了理论指导。
Abstract
Carbon capture and storage (CCS) is a promising strategy for reduction of CO2 emissions. Herein, CO2/N2 adsorption and separation in three SIFSIX-X-Cu (arrayed via SiF62- with Cu metal center, X = 2, 3, O) hybrid ultramicroporous materials at 298 K within 0-5 kPa were investigated by using grand canonical Monte Carlo (GCMC) simulation. Results showed that, in contrast to SIFSIX-2-Cu, CO2 adsorption in SIFSIX-3-Cu and SIFSIX-O-Cu reached saturation at 0.5 kPa and their CO2 adsorption capacity were 2.70 and 2.39 mmol·g -1 at 1 kPa, respectively. The CO2 adsorption capacity in CO2/N2 mixture barely decreased. SIFSIX-3-Cu and SIFSIX-O-Cu owned close pore sizes to CO2 dynamics diameter, thereby exhibiting high CO2 affinity with adsorption heat of 59 and 66 kJ·mol -1, respectively. Density functional theory (DFT) analyses showed only one CO2 molecule could be adsorbed in each hole and located at the center of SIFSIX-3-Cu and SIFSIX-O-Cu. Our results provide a theoretical guidance for developing ultramicroporous materials in adsorption and separation of CO2 at low pressure.
鲁效庆, 王茂槐. 混合超微孔材料中CO2/N2吸附与分离的理论研究[J]. 无机材料学报, 2020, 35(4): 469. Xiaoqing LU, Maohuai WANG.