三角形MOF孔道中CO_(2)捕获分离:孔径尺寸和官能团数量的影响

CO_(2) capture and separation in triangular MOF pores:effects of pore size and functional group number

日益增加的化石燃料消耗造成了大量CO_(2)排放,给我们的生活环境带来严重威胁,碳捕获、利用和封存(CCUS)技术应运而生。该技术的核心问题是CO_(2)捕获材料的设计与开发。设计了一系列具有不同孔径尺寸和—NO_(2)官能团数量的三角形MOF结构,并利用GCMC模拟研究了在298K和0.1~1.0bar条件下该系列MOF对CO_(2)的吸附分离性能。结果表明:随着孔径尺寸的增加,CO_(2)吸附量从S-1结构的0.39mmol/g增加到M-1结构的3.26mmol/g,随着孔径尺寸的持续增加,降低到L-1结构的1.71mmol/g。而官能团数量的增加则分别将S-1、M-1和L-1的CO_(2)吸附量提升到了S-2、M-2和L-2的1.03mmol/g、3.87mmol/g和2.78mmol/g。等温吸附热和CO_(2)相对于N_(2)/CH_(4)的选择性也呈现出类似的变化规律,范德华和库仑相互作用分析进一步阐明了不同结构间CO_(2)的吸附分离性能差异的本质原因。可为CO_(2)捕获材料的设计和开发提供重要指导。

The increasing consumption of fossil fuels has led to a significant amount of CO_(2) emissions,posing a serious threat to our living environment.Carbon capture,utilization,and storage(CCUS)technology has emerged in response to this issue.The core challenge of this technology lies in the design and development of CO_(2) capture materials.In this study,a series of triangular MOF structures with different pore sizes and numbers of—NO_(2) functional groups were designed,and the adsorption and separation performance of the MOFs for CO_(2) were investigated using GCMC simulations at 298K and 0.1~1.0bar.The results demonstrated that as pore size increased,the CO_(2) adsorption capacity increased from 0.39mmol/g in S-1 structure to 3.26mmol/g in M-1 structure,and then declined to 1.71mmol/g in L-1 structure with the continuous increase of pore size.Furthermore,the increase in the number of functional groups raised the CO_(2) adsorption capacities of S-1,M-1 and L-1 to 1.03mmol/g,3.87mmol/g,and 2.78mmol/g for S-2,M-2,and L-2,respectively.The isosteric heat of adsorption and the selectivity of CO_(2) relative to N_(2)/CH_(4) also exhibited similar trends.The analysis of van der Waals and Coulomb interactions further elucidated the inherent reasons for the differences in the adsorption and separation performance of CO_(2) among the different structures.This study provides important guidance for the design and development of CO_(2) capture materials.