【作者】 赵瑞；

【导师】 吴洪； 陈赞；

【作者基本信息】 天津大学 ， 化学工程， 2020， 硕士

【摘要】 碳捕集技术是解决能源气净化和缓解温室效应的关键。膜分离过程因其能耗低、环境友好等优点在CO₂分离领域显示出良好的发展前景。本论文以强化CO₂分离性能为目标,分别以共价有机骨架（COF）和二维纳米材料蛭石（VMT）为构筑单元,设计制备CO₂分离膜。在膜内构建气体分子传递通道并进行修饰改性,调控通道物理化学微环境,实现膜内分子筛分和溶解-扩散-反应多重选择机制的集成,提高膜的分离性能。主要研究内容如下:离子液体修饰共价有机框架孔道及膜分离性能强化:基于COFs具有规整的孔道结构及有机性质,通过杂化法以COF-300为构筑单元并利用离子液体（IL）进行修饰改性,制备IL@COF-300/Pebax混合基质膜,在Pebax高分子主体内构建气体分子传递通道。IL修饰后,COF-300孔道尺寸缩小,提高了CO₂和CH₄的扩散选择性;IL与CO₂具有强亲和性,强化了溶解选择性。所制备的IL@COF-300/Pebax膜CO₂渗透系数达1601 barrer,CO₂/CH₄选择性达39,与纯Pebax膜相比分别提高209%和87.5%,超越了2008年Robeson上限。氨基酸插层二维蛭石层板间通道及膜分离性能强化:基于VMT可剥离性和层间阳离子可交换性,以VMT纳米片为构筑单元,通过真空辅助组装法制备VMT膜,将氨基酸引入层间调控二维通道的物理化学微环境。氨基酸中的酸碱对作为CO₂的促进传递载体,强化了促进传递机制。氨基酸的插层调控VMT膜的层间距,强化了扩散机制。所制备的精氨酸（Arg）插层VMT膜（Arg-VMT）CO₂通量达330 GPU,CO₂/CH₄选择性32.1,与纯VMT膜相比分别提高49.3%和105%。此外,Arg-VMT膜具有良好的长期稳定性。无机酸刻蚀二维蛭石层板内通道及膜分离性能强化:基于VMT的可刻蚀性,通过无机酸HCl刻蚀制备多孔蛭石（HVMT）纳米片,利用真空辅助组装法制备HVMT膜,构建膜内二维层板间通道和层板内通道。经HCl刻蚀后,蛭石层板的Mg、Al和Ca等阳离子溶出形成空穴,提高了孔体积和比表面积,增加了气体分子在VMT层板内的传递通道。将富含氨基的PEI分子引入HVMT层间,调控了膜通道尺寸和化学微环境,强化了溶解-扩散-反应机制。PEI-HVMT膜具有良好的CO₂/CH₄分离性能,CO₂通量达568 GPU,选择性27.6,与VMT膜相比通量和选择性分别提高了157%和89%。PEI-HVMT膜具有良好的长期稳定性。更多还原

【Abstract】 Carbon capture technology is the key to energy gas purification and mitigation of greenhouse effect.The membrane separation technology shows a good prospect in the CO₂ separation field due to its advantages of low energy consumption and environmen-tal friendliness.Aiming at enhancing CO₂ separation performance,CO₂ separation membranes have been prepared using covalent organic framework（COF）and two-di-mensional nanomaterial vermiculite（VMT）as building blocks,constructing gas mo-lecular transport channels and modification,regulating the physical and chemical mi-croenvironment to realize the integration of molecular sieve and dissolution-diffusion-reaction multi-selection mechanisms,and to improve the separation performance of the membranes significantly.The details are as follows:Ionic liquid（IL）modified pore channels of COF and enhanced separation perfor-mance of membranes:Based on the regular pore structure and organic properties of COFs,the IL@COF-300/Pebax membranes are fabricated by hybrid method with COF-300 modified by ionic liquid（IL）as the building blocks,and constructing CO₂ transport channels in Pebax matrix.The pore size of COF-300 decreases,improving the diffusion selectivity of CO₂ and CH₄.Moreover,IL affords strong affinity toward CO₂ to improve the solubility selectivity.The IL@COF-300/Pebax membrane shows high CO₂ perme-ability of 1601 barrer with CO₂/CH₄ selectivity of 39,which are 209%and 87.5%higher than that of pristine membrane,respectively,surpassing the 2008 Robeson upper bound.Amino acid intercalation of two-dimensional VMT interlaminar channels and sep-aration performance enhancement of membranes:Based on exfoliability and cation ex-changeability of VMT,VMT membranes are fabricated by vacuum-assisted self-assem-bly using VMT nanosheets as the building blocks.Amino acids are introduced into the VMT to regulate the physical and chemical microenvironment of two-dimensional transport channels.The acid-base pairs in amino acids provide carriers for CO₂transport thus strengthen the reaction mechanism of membranes.The amino acids en-large the interlayer spacing of VMT membranes and strengthen the diffusion mecha-nism.The Arg-VMT membrane shows high CO₂ permeance of 330 GPU with CO₂/CH₄selectivity of 32.1,which are 49%and 105%higher than that of VMT membrane,re-spectively.In addition,the Arg-VMT membrane exhibit good long-term operation stability.Inorganic acid etched two-dimensional VMT laminate channels andseparation performance enhancement of membranes:Based on the etchability of VMT,porous vermiculite（HVMT）nanosheets are prepared by HCl etching,and HVMT membranes are fabricated by vacuum assisted self-assembly method to construct two-dimensional interlaminar channels and laminate channels.The Mg、Al and Ca cations of VMT can be dissolved to form nanopores under appropriate HCl concentration and etching reac-tion conditions,improving the porosity and specificsurface area of VMT,and increas-ing the transport channels on VMT laminates.The amino-rich PEI molecules are intro-duced into HVMT membranes to regulate the channel size and to enhance the diffusion of CO₂.Amino groups afford affinity to CO₂ and thus enhance dissolution and reaction mechanism.The PEI-HVMT membrane shows high CO₂ permeance of 568 GPU with CO₂/CH₄ selectivity of 27.6,which are 157%and 89%higher than that of VMT mem-brane,respectively.In addition,the PEI-HVMT membrane exhibits good long-term operation stability.更多还原