不同非对称介孔碳掺杂的混合基质膜分离CO_(2)性能的提升机制  

Improvement mechanism of CO_(2) separation performance of mixed matrix membranes doped with different asymmetric mesoporous carbon

作　　者：王沛 张珂 王挺[1] 吴礼光[1] 李春娟[1] WANG Pei;ZHANG Ke;WANG Ting;WU Liguang;LI Chunjuan(School of Environmental Science and Engineering,Zhejiang Gongshang University,Hangzhou 310012)

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6期318-329,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.21776250);浙江省自然科学基金(No.LY19B060004,LY20B060001)。

摘　　要：为了阐明膜分离CO_(2)性能提升机制,以浸渍碳化-硬模板法制备的非对称介孔碳材料作为掺杂组分,通过原位聚合法构建不同聚酰亚胺(Polyimide,PI)混合基质膜.同时,结合气体吸附及渗透实验系统研究了不同非对称介孔碳材料掺杂后对混合基质膜分离CO_(2)性能提升机制.结果表明,多次浸渍碳化过程使碳材料中无序结构转变为规则孔道结构.非对称结构可以在介孔碳材料中引入丰富的晶体缺陷结构,从而使材料中产生很多可以与CO_(2)分子形成强作用的C原子sp2和sp3杂化,因此,各个非对称介孔碳材料都具有优异的CO_(2)吸附性能.浸渍碳化次数过多碳材料中孔道变得更为紧致和规则,晶体缺陷结构减少,导致材料对CO_(2)气体吸附性能下降.低掺杂量非对称介孔碳的加入不能显著提升膜分离中CO_(2)溶解性能.但C原子sp2和sp3杂化作为CO_(2)的主要捕获中心,在膜中形成CO_(2)促进扩散过程,从而显著提升混合基质膜对CO_(2)的扩散选择性.非对称介孔碳材料掺杂后混合基质膜的最优CO_(2)/N2选择性可达40,接近纯PI膜的10倍,超过CMK-3构建的混合基质膜的2倍.To explore the improvement mechanism of membrane performance for CO_(2) separation,asymmetric mesoporous carbon materials was employed as nanofillers to fabricate polyimide(PI)mixed matrix membranes(MMMs)via in-situ polymerization.The mechanism for enhancing CO_(2) separation performance of MMMs after incorporating different asymmetric mesoporous carbon was explored by combining gas adsorption and permeation experiments.The results indicated that multiple impregnations-carbonization cycles during the preparation using hard-template method would transfer the disordered structure in mesoporous carbon to an ordered and regular pore structure.Asymmetric structures would introduce many crystal defect structures into mesoporous carbon,thus causing the formation of abundant C atoms with sp2 and sp3 hybridizing and strong interactions with CO_(2) molecules.Therefore,all asymmetric mesoporous carbon had good adsorption performance for CO_(2).The pores in mesoporous carbon became more compact and regular due to excessive impregnation-carbonization cycles(four times),which resulted in a decrease of crystal defect structures of mesoporous carbon and a reduction of their CO_(2) adsorption performance.Asymmetric mesoporous carbon cannot significantly improve the CO_(2) solubility performance of MMMs at low addition content in MMMs.The C atoms with sp2 and sp3 hybridization served as the main capture center for CO_(2) molecules,which caused the CO_(2)-facilitated diffusion in the membrane,thereby significantly improving the diffusion selectivity of MMMs for CO_(2).The optimum CO_(2)/N2 selectivity of MMMs incorporating asymmetric mesoporous carbon could reach 40,which was close to 10 times that of the neat PI membrane and exceeded 2 times that of the MMMs including CMK-3.

关 键 词：非对称介孔碳 聚酰亚胺混合基质膜 CO_(2)吸附 气体渗透性 CO_(2)促进扩散 

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]