有机配体结构对ZIFs材料结晶度及其CO_(2)吸附性能的影响机制  

The influence mechanism of organic ligand structure on the crystallinity and CO_(2)adsorption performance of ZIFs materials

作　　者：刘晗翀 吴梦雅 吴礼光[1] 王挺[1] LIU Hanchong;WU Mengya;WU Liguang;WANG Ting(School of Environmental Science and Engineering,Zhejiang Gongshang University,Hangzhou 310018)

机构地区：[1]浙江工商大学,环境科学与工程学院,杭州310012

出　　处：《环境科学学报》2024年第8期110-121,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金资助项目(No.22078291);浙江工商大学“数字+”学科建设管理项目(No.SZJ2022B014)。

摘　　要：沸石咪唑酯框架(ZIFs)被认为是一种用于高效CO_(2)捕获的多孔晶体材料,其晶体结构是影响CO_(2)吸附性能的关键因素之一.本文分别选用2-甲基咪唑、2-乙基咪唑和3-氨基-1,2,4-三唑作为有机配体,通过反相微乳液制备了ZIFs材料用于CO_(2)的捕获.结合ZIFs材料结构表征、气体吸附、巨正则蒙特卡洛(GCMC)以及分子动力学(MD)模拟,研究了有机配体对ZIFs的结晶度、孔结构和CO_(2)吸附性能的影响.结果表明:采用2-甲基咪唑合成的ZIF-8-M与2-乙基咪唑合成的ZIF-8-N,两者除了结晶度外其它结构差异并不十分显著,但ZIF-8-M材料CO_(2)吸附容量较高,可达0.69 mmol·g^(-1);ZIF-8-N结晶度、比表面积和孔隙率较小,CO_(2)吸附容量也较低,仅为0.29 mmol·g^(-1).提高合成温度,ZIF-8-M和ZIF-8-N结晶度均明显增大,CO_(2)吸附容量也显著提高,这可能是由于高结晶度的ZIFs更有利于氢键的形成和π-π堆积作用的发生.当温度从30℃升高到60℃时,ZIF-8-M的CO_(2)吸附容量提高了2.2倍,ZIF-8-N的CO_(2)吸附容量增大了4.9倍.此外,GCMC和MD模拟结果表明:随着晶体结构无序化程度的增加,ZIF-8-M对CO_(2)分子的吸附能由-52.5 kcal·mol^(-1)增大至511.0 kcal·mol^(-1),吸附能力下降,吸附的CO_(2)分子个数明显下降.再次验证了结晶度是影响ZIFs材料吸附CO_(2)性能的关键结构参数.Zeolite imidazole ester frameworks(ZIFs)are considered as porous materials for efficient CO_(2)adsorption and capture,and their crystal structure is one of the key factors affecting CO_(2)adsorption performance.In this work,2-methylimidazole,2-ethylimidazole,and 3-amino-1,2,4-triazole were employed as organic ligands to prepare ZIFs by reverse microemulsion for CO_(2)capture.Combining structure characterization,gas adsorption,grand canonical Monte Carlo(GCMC),and molecular dynamics(MD)simulation,the influence of organic ligands on the crystallinity,pore structure,and CO_(2)adsorption performance of ZIFs was extensively investigated.The results showed that ZIF-8-M synthesized using 2-methylimidazole and ZIF-8-N synthesized using 2-ethylimidazole had the similar structures except for crystallinity.However,ZIF-8-M had a high CO_(2)adsorption capacity,up to 0.69 mmol·g^(-1).The synthesized ZIF-8-N had lower crystallinity,specific surface area,and porosity,thus exhibiting lower CO_(2)adsorption capacity(only 0.29 mmol·g^(-1)).By increasing the temperature in the ZIF preparation,the crystallinity of ZIF-8-M and ZIF-8-N significantly improved,thus enhanced their CO_(2)adsorption capacity,which might be ascribed to ZIFs with high crystallinity were more conducive to the formation of hydrogen bonds and the occurrence ofπ-πstacking.When the temperature increased from 30℃to 60℃,the CO_(2)adsorption capacity of ZIF-8-M increased by 2.2 times,and the CO_(2)adsorption capacity of ZIF-8-N increased by 4.9 times.In addition,GCMC and MD simulation results showed that as the degree of disorder in the crystal structure increased,adsorption energy of ZIF-8-M for CO_(2)molecules increased from-52.5 kcal·mol^(-1)to 511.0 kcal·mol^(-1),thus the adsorption capacity decreased.The number of CO_(2)molecules adsorbed also significantly decreased.It further verified that the crystallinity was the key structural parameter that affected the CO_(2)adsorption performance of ZIFs materials.

关 键 词：反相微乳液 ZIF-8 结晶度 CO_(2)吸附 分子动力学模拟 

分 类 号：TB332[一般工业技术—材料科学与工程] X701[环境科学与工程—环境工程]