现代化工

现代化工 ›› 2026, Vol. 46 ›› Issue (10) : 138-145. DOI: 10.16606/j.cnki.issn0253-4320.2026.10.024

科研与开发

IL调控ZIF-8孔道用于混合基质膜CO₂/CH₄分离研究

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ZIF-8 pores confined by ionic liquids for mixed matrix membranes in CO₂/CH₄ gas separation research

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Received		Published
2025-12-08		2026-10-20
Issue Date	Revised Date
2026-10-14	2025-12-08

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摘要

为开发高性能CO₂/CH₄分离混合基质膜,离子液体@金属有机骨架(IL@MOF)复合材料的制备已成为研究热点。以二氯甲烷为活化介质,采用“活化-浸渍”法制备不同[BMIM][BF₄]负载量的IL@ZIF-8复合材料,并将其作为填料掺入聚砜(PSF)基质制备混合基质膜,系统探究填充颗粒的结构特性及其对膜CO₂/CH₄分离性能的影响。研究表明离子液体可稳定负载于ZIF-8的方钠石(SOD)笼内,且IL@ZIF-8填料在PSF基质中分散均匀、界面相容性良好。IL负载量为2.64、填料含量10%的IL@ZIF-8/PSF-2膜表现出最优分离性能:与纯PSF膜相比CO₂渗透性提升56%,达到15.09 Barrer;CO₂/CH₄分离选择性提升52%,达到42.5。吸附扩散机理研究表明IL@ZIF-8填料的选择性吸附与扩散筛分产生的协同效应,是混合基质膜分离性能提升的核心机制。

Abstract

The development of high-performance CO₂/CH₄ separation mixed matrix membranes has positioned the preparation of ionic liquid-@metal-organic framework (IL@MOF) composites as a prominent area of research.Utilizing dichloromethane as the activation medium,IL@ZIF-8 composite materials with varying loading of [BMIM][BF₄] were synthesized via the “activation-impregnation” method.These composites were incorporated as fillers into polysulfone (PSF) to fabricate mixed matrix membranes.A systematic investigation was conducted to assess the structural characteristics of the filled particles and their influence on the CO₂/CH₄ separation performance of the membranes.Findings indicate that ionic liquids can be stably incorporated within the ZIF-8 sodalite (SOD) cage,resulting in the uniform dispersion of the IL@ZIF-8 filler within the PSF matrix and demonstrating favorable interfacial compatibility.The IL@ZIF-8/PSF-2 membrane,featuring an IL loading of 2.64 and a filler content of 10%,exhibited optimal separation performance:CO₂ permeability increased by 56% compared to the pure PSF membrane,achieving 15.09 Barrer,while the CO₂/CH₄ separation selectivity improved by 52% to 42.5.Research into the adsorption and diffusion mechanisms suggests that the synergistic effect arising from the selective adsorption and diffusion sieving of the IL@ZIF-8 fillers constitutes the primary mechanism for enhancing the separation performance of mixed matrix membranes.

Graphical abstract

关键词

混合基质膜 / 离子液体 / 金属有机骨架材料 / 气体分离

Key words

mixed matrix membranes / ionic liquid / metal-organic frameworks / gas separation

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companyList=[AuthorCompany(id=1317175116648903047, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1317138598442004989, xref=null, ext=[AuthorCompanyExt(id=1317175116695040396, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1317138598442004989, companyId=1317175116648903047, language=EN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=School of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, China), AuthorCompanyExt(id=1317175116716011917, tenantId=1226480274814496768, journalId=1226484258170171394, articleId=1317138598442004989, companyId=1317175116648903047, language=CN, country=null, province=null, city=null, postcode=null, companyName=null, departmentName=null, remark=河南科技学院化学化工学院, 河南新乡 453003)])])] 郭昂,吕臣贞,刘陶陶,李英. IL调控ZIF-8孔道用于混合基质膜CO₂/CH₄分离研究[J]. 现代化工, 2026, 46(10): 138-145 DOI:10.16606/j.cnki.issn0253-4320.2026.10.024

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天然气、煤层气及沼气等能源气中普遍伴生10%~80%的CO₂,形成典型CO₂/CH₄混合体系,CO₂不仅降低CH₄净热值、引发输气设备腐蚀^[1];还与CH₄同属强效温室气体,无序排放已成为全球气候变化的关键诱因^[2]。因此,开发高效低能耗CO₂/CH₄分离技术,实现“CH₄高纯度回收-CO₂定向捕集”,是低品位甲烷开发的技术前提和“双碳”目标落地的核心保障^[3]。气体膜分离技术凭借能耗低、操作简便、可规模化应用等显著优势,在CO₂/CH₄分离领域展现出广阔前景^[4]。相较于吸附^[5]、低温精馏^[6]等传统分离技术,气体膜分离无需复杂相变过程,兼具设备占地小、绿色节能等特点^[7-8]。然而,现有膜材料仍面临诸多瓶颈:聚合物膜受限于渗透-选择性“Trade-off”制约,且易溶胀老化^[9];分子筛^[10]、金属有机框架(MOF)^[11]等无机膜虽选择性优异,但是机械强度低、规模化制备难。混合基质膜(MMMs)通过无机填料-有机基质”复合设计,有效突破单一膜材料的固有缺陷,已成为最具工业化应用前景的膜材料^[12]。

MOF材料因孔径可调、比表面积高、表面可修饰等优势,成为MMMs填料的研究热点^[13],但单纯MOF与聚合物基质界面结合弱、长期运行性能衰减。离子液体(IL)修饰MOF形成IL@MOF复合材料,不仅通过表面配位作用调控MOF的分散性,降低其与聚合物基质的界面能,还凭借对CO₂的特异性吸附能力形成连续的气体传输通道,实现吸附-筛分-传质功能集成^[14-15],混合基质膜的CO₂渗透性与选择性较聚合物膜提升幅度明显,同时机械强度与耐老化性能也得到强化。IL@MOF复合材料的结构调控与规模化制备已成为研究热点。

Ferreira等^[16]通过原位合成法制备IL@MOF复合材料,并掺入Matrimid^®5218制备MMMs用于CO₂/N₂分离,孔结构变化证明成功将IL负载到MOF孔道中,在20%最优填充量时CO₂/N₂选择性为26.9。Guo等^[17]通过两步吸附/渗透策略,将离子液体[BMIM][PF₆]限制在ZIF-8纳米笼中,制备的IL@ZIF-8/Pebax混合基质膜中,IL负载量增加CO₂/N₂选择性持续提升,IL₈@ZIF-8/Pebax MMMs(25%填充量)表现最佳,CO₂渗透性117 Barrer、CO₂/N₂选择性84.5,超越2008年Robeson上限。

目前,IL@MOF复合材料的制备主要有离子热原位合成法、湿浸渍法、机械研磨法、真空浸渍法等。离子热原位合成法可避免有机溶剂竞争,但需特定反应体系,高温下易发生非预期配位反应,原料利用率低且IL负载量难以精准调控^[18];湿浸渍法操作简单,IL负载量可通过溶剂比例灵活调控,MOF结构保留完整,但高负载量下易出现IL团聚,且有机溶剂容易残留^[19];机械研磨法无溶剂污染,操作快速高效,适合规模化制备,但IL易局限于MOF表面,且研磨过程可能破坏MOF晶体结构,分散均匀性较差^[20];真空浸渍法利用真空环境去除MOF孔道内的溶剂分子,使IL高效、均匀地渗透至MOF孔道及表面^[21],通常需对MOF材料进行真空干燥活化预处理,以去除孔道内的溶剂分子,但干燥后的MOF样品在后续混合基质膜制备中分散困难,极易产生非选择性界面缺陷。

二氯甲烷可作为MOF活化溶剂与IL溶解介质,兼具客体分子脱除高效、晶体结构保留完整、低沸点易脱除等优势,适配MOF后功能化修饰,兼容湿浸渍法和真空浸渍法,在IL@MOF复合材料制备领域具有不可替代的应用价值。

本文以二氯甲烷为活化介质,常温下完成纳米ZIF-8颗粒的活化处理,摒弃真空干燥步骤,直接采用真空加热浸渍法,在MOF未干燥状态下精准调控温度、时间等参数,制备不同[BMIM][BF₄]负载量的IL@ZIF-8复合材料。通过“二氯甲烷活化-真空浸渍”设计保障IL高效负载并避免MOF干燥后分散难题,在此基础上,进一步探究典型负载量 IL@ZIF-8的气体吸附性能,并将其引入聚砜基质制备MMMs,研究复合材料对CO₂/CH₄分离性能的提升机制,为IL@MOF复合材料以及高效气体分离膜的制备提供新的技术思路。

1 材料与试剂

1.1 材料

聚砜(PSF,M_w=80 000,纯度98%),上海麦克林生化科技股份有限公司;Ar、CO₂、CH₄(纯度均为99.99%),河南源正特种气体有限公司。

六水合硝酸锌[Zn(NO₃)₂·6H₂O,分析纯99.0%]和2-甲基咪唑(2-methyl imidazole,分析纯99.0%),西格玛奥德里奇(上海)贸易有限公司;1-丁基-3-甲基咪唑四氟硼酸盐([BMIM][BF₄],纯度99%),上海成捷化学有限公司;甲醇(分析纯99.5%)、二氯甲烷(分析纯99.0%)和氯仿(分析纯99.0%),天津科密欧化学试剂有限公司。

1.2 仪器

HMS-203D型磁力搅拌器,上海沪析实业有限公司;LC-JA1003型电子天平,力辰科学仪器有限公司;H1750型台式高速离心机,湘仪离心机厂;DZF-6021型真空干燥箱,上海一恒科学仪器有限公司;RH-120S型超声探头破碎仪,东莞歌能超声设备有限公司;KQ5200V型超声波清洗器,昆山舒美超声仪器有限公司。

2 实验部分

2.1 ZIF-8纳米颗粒的合成

准确称量0.90 g六水合硝酸锌分散于50 mL甲醇,搅拌成A液;另取2.00 g 2-甲基咪唑溶于 50 mL甲醇得到B液。对A和B液进行超声处理至溶质完全溶解后,将A液加入B液中,室温搅拌反应1 h。反应结束后,进行离心分离,收集底部颗粒并用30 mL甲醇超声洗涤3次去除未反应的金属盐和配体。所得固体于室温下晾干6 h,随后转移至60℃鼓风干燥箱中干燥24 h。

2.2 IL@ZIF-8复合材料的制备

取经甲醇洗涤(步骤同2.1,未干燥)的ZIF-8样品,用30 mL二氯甲烷浸泡并搅拌12 h完成活化;离心分离后,将底部湿润固体转移至玻璃小瓶,加入10 mL离子液体[BMIM][BF₄]浸没固体,超声水浴处理10 min以确保二者充分接触。将玻璃小瓶置于真空干燥箱中,控制浸渍温度(80、100、120℃)与时间(24、48、96 h),抽真空使[BMIM][BF₄]渗入ZIF-8的SOD笼中。浸渍结束后,样品用30 mL无水甲醇超声洗涤2次,以去除颗粒表面吸附的离子液体。

2.3 PSF膜以及ZIF-8/PSF、IL@ZIF-8/PSF混合基质膜的制备

将真空干燥后的PSF颗粒溶于氯仿,配制质量分数8%的PSF铸膜液,密封后室温高速搅拌24 h。将光滑玻璃板固定于刮膜台并加热至40℃,以 10 mm/s速度刮涂;刮涂后于40℃玻璃板上干燥 5 min,取下薄膜后依次经60℃干燥24 h、60℃真空干燥24 h,制得PSF自支撑薄膜。

ZIF-8/PSF、IL@ZIF-8/PSF混合基质膜的制备是在纯PSF膜工艺基础上增加纳米颗粒掺杂步骤。取经甲醇洗涤(未干燥)的ZIF-8或IL@ZIF-8颗粒,用氯仿超声清洗2次以置换溶剂;向湿润凝胶状固体中加适量氯仿,探头超声10 min(冰水冷却、密封防氯仿挥发)。将制备的纳米颗粒-氯仿溶胶逐滴加入PSF-氯仿铸膜液中,密封高速搅拌24 h。铸膜液理论配比:纳米颗粒/(纳米颗粒+PSF)=10%,(纳米颗粒+PSF)/总质量=8%。后续刮膜及干燥流程与纯PSF膜完全一致。

2.4 纳米颗粒和混合基质膜的表征

采用Bruker D8 Advance A25型X-射线衍射仪(扫描速率5°/min,角度2~40°)分析纳米颗粒和薄膜的晶相结构;数显万分尺测量薄膜厚度;高分辨扫描电镜S5500观测纳米颗粒形貌;JSM-7800F高分辨扫描电镜(测试前薄膜经液氮冷冻30 min、淬断及喷金处理)观察薄膜截面形貌;德国Netzsch STA 449 F5 Jupiter同步热分析仪(升温速率10℃/min,室温~1 000℃,空气流速40 mL/min)研究热稳定性;Lambda FTIR-7600傅里叶变换红外光谱仪(扫描范围650~4 000 cm^-1,分辨率4 cm^-1)分析化学结构;ASAP 2020麦克物理吸附仪(77 K下N₂吸附等温线)分析颗粒比表面积及孔分布;智能重量吸附仪IGA测试25℃下CO₂、CH₄物理吸附等温线,利用Langmuir吸附模型[式(1)]拟合CO₂、CH₄吸附曲线并按[式(2)]计算溶解平衡常数。

(1)${Q}_{i}=\left({C}_{\mathrm{H}}bp\right)/(1+bp)$

式中:Q_i为吸附质的吸附容量,cm³(STP)/cm³;p为平衡时分压,cmHg;C_H为Langmuir平衡常数,cm³(STP)/cm³;b为Langmuir亲和常数,cmHg^-1。

溶解平衡常数S_i[cm³(STP)·cm^-3·cmHg^-1]为吸附量Q_i与压力p的比值[式(2)]。

(2)${S}_{i}={Q}_{i}/{p}_{i}=\left({C}_{\mathrm{H}}b\right)/(1+bp)$

2.5 PSF膜和混合基质膜的气体渗透性能测试

采用Wicke-Kallenbach法,通过配备TDX-01填充柱与热导检测器的福立GC 9790Ⅱ气相色谱仪进行气体渗透测试。25℃下,将有效面积0.95 cm²的薄膜密封于不锈钢组件中;原料侧通入3 bar压力、总流量100 mL/min、体积比50/50的CO₂/CH₄混合气,渗透侧保持常压并以10 mL/min的Ar作吹扫气。每张膜测试不少于5 h以确保达到渗透平衡。膜的气体渗透性由公式(3)计算得到。

(3)${P}_{i}=\left({q}_{i}l\right)/\left(A\mathrm{\Delta }{P}_{i}\right)$

式中:P_i为气体渗透性,1 Barrer=10^-10cm³(STP)·cm·cm^-2·s^-1·cmHg^-1;q_i为气体在标准温度和压力(STP)下的体积流量,cm³/s;l为膜厚度,cm;A为膜有效面积,cm²;ΔP_i为膜两侧压力差,cmHg。

渗透率P_i(Barrer)亦表示为扩散系数D_i(cm²/s)与吸附系数S_i[cm³(STP)·cm^-3·cmHg^-1]的乘积,如式(4)所示。

(4)${P}_{i}={D}_{i}\times {S}_{i}$

分离因子按式(5)计算。

(5)${\alpha }_{ij}=({y}_{i}/{y}_{j})/({x}_{i}/{x}_{j})$

其中,x_i/x_j、y_i/y_j分别为组分x和y在进料侧和渗透侧的摩尔分数。

3 结果与讨论

3.1 纳米颗粒以及薄膜样品的TG、XRD、FT-IR、SEM表征

图1为填充颗粒与薄膜在空气气氛下热重(TG)曲线。由图可见,ZIF-8在80~200℃区间的失重主要是ZIF-8孔道和表面吸附溶剂分子和水挥发所致;当温度升至450℃以上时,ZIF-8骨架结构开始坍塌,质量急剧下降;700℃以后TG曲线趋于平稳,残余质量分数为34.11%,对应残余产物ZnO。与纯ZIF-8不同,IL@ZIF-8样品在400℃前质量损失可忽略不计,这归因于IL占据ZIF-8孔道后,其孔道及表面吸附的溶剂分子显著减少。IL@ZIF-8的热稳定性较ZIF-8略有降低,400℃以上即发生骨架坍塌,900℃后TG曲线出现平台。基于ZIF-8与IL@ZIF-8在空气气氛中残余质量分数的差异,可计算得到ZIF-8的SOD笼内[BMIM][BF₄]离子液体的负载量(以笼内[BMIM][BF₄]的分子个数表示),不同温度与时间条件下的具体负载量见表1。对于纯PSF膜及IL@ZIF-8/PSF混合基质膜二者均在500℃以上出现尖锐失重峰,表明两种薄膜材料在500℃以下具有良好的热稳定性。

图2(a)为IL@ZIF-8与ZIF-8的X射线衍射(XRD)图谱,二者特征峰基本一致,表明IL负载未显著改变ZIF-8晶相结构。此外未观察到IL特征峰,说明在保持ZIF-8框架稳定的前提下,IL成功负载到ZIF-8的SOD笼中。进一步分析可见,IL@ZIF-8中ZIF-8的特征衍射峰峰强明显降低且发生低角度偏移,这是由于IL嵌入ZIF-8孔道及晶格间隙撑开骨架并且IL与ZIF-8咪唑环间的氢键作用引发晶格轻微膨胀,进而增大晶面间距所致。图2(b)为纯PSF膜与MMMs的XRD图谱。纯PSF膜在12~25°范围内呈无定形宽包;当掺入ZIF-8及2种IL@ZIF-8颗粒后,MMMs中出现ZIF-8的(110)、(200)、(211)特征衍射峰,证实3种填充颗粒均在膜中稳定存在。

图3(a)为ZIF-8与IL@ZIF-8-1粉末的红外谱图(FT-IR)。两种样品均出现1 145 cm^-1(咪唑环C—N伸缩振动)与1 311 cm^-1(咪唑环弯曲振动)的特征峰,说明IL负载未破坏ZIF-8的咪唑环结构。ZIF-8在1 180 cm^-1处的2-甲基咪唑环C—H面内弯曲振动峰,在IL@ZIF-8中红移至1 172 cm^-1,这是由于咪唑环C—H(氢键给体)与[BF₄]^-(氢键受体)形成氢键,使C—H键电子云密度降低、键长增加,导致振动能量减小^[22]。此外,IL@ZIF-8在 1 023、1 058、1 112 cm^-1处出现[BMIM][BF₄]的[BF₄]^-的特征分裂峰^[23],进一步证明IL稳定负载于ZIF-8孔道内。聚砜(PSF)的强极性基团红外吸收强度远高于低负载量的ZIF-8,且二者部分峰重叠,因此纯PSF膜及MMMs中主要呈现PSF的红外峰,仅在952 cm^-1处可观测到ZIF-8咪唑环的面外弯曲振动峰[图3(b)]。ZIF-8及IL@ZIF-8基MMMs均含该特征峰,表明填充颗粒在PSF基质中稳定性良好。

图4为IL负载前后ZIF-8的扫描电镜(SEM)图,可见纳米颗粒形貌(不规则小球)与尺寸(直径约80 nm)均未发生明显变化。图5为PSF纯膜与MMMs的截面SEM图,纯PSF膜截面致密,无明显孔结构;当引入相同掺杂量(10%)的不同填充颗粒后,MMMs呈现聚合物链网络状结构,未观察到明显颗粒团聚,表明填充颗粒与PSF基质具有良好相容性。

3.2 纳米颗粒以及薄膜样品的吸附表征

图6(a)为ZIF-8及3种不同IL负载量的IL@ZIF-8材料在77 K下的氮气吸附-脱附等温线。经计算发现,材料比表面积随离子液体负载量增大呈显著下降趋势,孔容变化规律与比表面积一致,具体数据如表2所示。图6(b)为采用Horváth-Kawazoe(HK)模型分析得到的ZIF-8及3种IL@ZIF-8样品的孔径分布曲线。随着离子液体负载量提升,高负载量复合材料在0.8 nm与1.0 nm处的特征孔明显消失,同时在0.5 nm以前出现新的微孔,证实通过离子液体负载可实现ZIF-8孔结构的精准调变,成功制备出超微孔丰富的复合材料。

图7为ZIF-8及两种IL@ZIF-8样品在25℃下的CO₂与CH₄吸附等温线,采用Langmuir模型[式(1)]对吸附曲线进行拟合,其中圆点为实验测试数据,实线为Langmuir模型拟合曲线,拟合所得吸附常数如表3所示。结果表明,随离子液体负载量增加,IL@ZIF-8对CO₂与CH₄的饱和吸附量均显著下降,而吸附亲和常数b则呈上升趋势,且CO₂吸附亲和常数的增幅远大于CH₄,使得复合材料的CO₂/CH₄吸附选择性显著提升。根据拟合曲线计算,当CO₂/CH₄摩尔比为1∶1时,材料的理想吸附溶液理论(IAST)吸附选择性由ZIF-8的8.36提升至IL@ZIF-8(2.64)的19.94。

图8为纯聚砜膜及混合基质膜在25℃等温条件下的CO₂与CH₄吸附等温线。实验结果表明,在PSF聚合物基体中引入纳米颗粒填料后,混合基质膜对CO₂和CH₄平衡吸附量均显著提升。采用Langmuir吸附模型[式(1)]对吸附等温线进行非线性拟合,拟合所得的Langmuir特征参数列于表4。两类膜其对CH₄的吸附能力均相对较弱,且在高压吸附区,CH₄在膜材料吸附位点上呈现出明显的竞争排斥效应,导致吸附量增长趋于平缓甚至略有下降。

3.3 PSF膜以及IL@ZIF-8/PSF混合基质膜的气体分离性能

图9为PSF纯膜及混合基质膜在3 bar压力、25℃下的气体分离性能数据。PSF纯膜的CO₂渗透性为9.70 Barrer,CO₂/CH₄分离选择性为27.9;当向PSF基质中掺杂10% ZIF-8纳米颗粒时,CO₂/CH₄选择性提升至32.1,CO₂渗透性提高至15.66 Barrer。进一步采用IL@ZIF-8作为填料,制备两种混合基质膜IL@ZIF-8/PSF-1(IL负载量2.33)与IL@ZIF-8/PSF-2(IL负载量2.64),且填料掺杂量均为10%。性能测试表明,IL的引入进一步强化膜的选择分离能力:CO₂/CH₄选择性分别提升至36.7和42.5;相较于ZIF-8/PSF膜,CO₂渗透性略有降低,为15.09 Barrer,仍高于PSF纯膜。IL负载量最高的IL@ZIF-8/PSF-2膜性能最优,相较于PSF纯膜,其CO₂/CH₄选择性提升52%,CO₂渗透性提升56%,实现渗透性与选择性的协同优化。混合基质膜分离性能的提升机制可归结为两方面:一是纳米填料(ZIF-8、IL@ZIF-8)在PSF基质中分散性良好;二是IL修饰调控ZIF-8的孔道微环境,增强对CO₂分子的选择性吸附与扩散传质能力,从而强化膜的分离性能。

利用表4中模拟得到的Langmuir吸附等温线参数,根据公式(2)计算得到CO₂和CH₄在不同膜上的溶解平衡常数以及相应的选择性,并根据膜的渗透性数据计算得到CO₂和CH₄在不同杂化膜上的扩散系数和相应扩散选择性,探究膜性能提升的分离机制,相关数据见表5。

结合吸附/扩散数据及膜分离性能可知,吸附与扩散作用的协同调控是混合基质膜CO₂/CH₄分离性能的关键因素:吸附作用主导分离选择性的提升,扩散作用则保障CO₂渗透性并进一步优化分离效能;其中吸附作用通过选择性捕获CO₂成为分离选择性提升的核心驱动力,未修饰ZIF-8掺杂体系中,10% ZIF-8掺杂使膜的CO₂吸附系数从纯PSF膜的0.061 5升至0.072 1 cm³(STP)·cm^-3·cmHg^-1,吸附选择性从5.39提升至5.82,IL@ZIF-8体系中低、高IL负载量样品吸附选择性分别达6.01和6.75,而扩散作用通过“构建高效传质通道-抑制非目标气体扩散”双重路径提供关键支撑,纯ZIF-8掺杂体系中CO₂扩散系数从纯PSF膜的1.58×10^-8增至2.14×10^-8 cm²/s,扩散选择性从5.17升至5.38,IL修饰后IL@ZIF-8/PSF-1及IL@ZIF-8/PSF-2膜的扩散选择性进一步提升至6.10和6.23,IL@ZIF-8/PSF-2膜凭借高吸附选择性(6.75)与扩散选择性(6.23)的协同优势实现最优分离性能,证实吸附选择性强化与扩散选择性提高的协同作用是混合基质膜突破纯PSF膜性能瓶颈的核心机制,二者的协同效应为混合基质膜的性能调控提供明确方向。

4 结论

针对IL@MOF复合材料的制备问题,创新采用二氯甲烷介入的“活化-浸渍”法制备IL@ZIF-8复合材料并与聚砜复合制备混合基质膜;通过热重、XRD、红外、电镜表征及吸附-分离性能测试,系统探究不同IL负载量IL@ZIF-8填料的孔道结构、吸附性能以及对PSF基混合基质膜CO₂/CH₄分离性能的调控机制。研究结果表明:IL可稳定负载于ZIF-8的SOD笼内,通过孔道占据与氢键作用调控其孔结构与表面特性,使IL@ZIF-8呈现超微孔富集特征,CO₂/CH₄吸附选择性显著提升;将10% IL@ZIF-8掺入PSF基质后,填料分散性良好且与基体相容性优异,混合基质膜的分离性能实现协同优化,其中IL负载量2.64的IL@ZIF-8/PSF-2膜性能最优,相较于纯PSF膜,CO₂渗透性提升56%,CO₂/CH₄分离选择性提升52%;吸附-扩散机制研究表明,吸附作用主导分离选择性提升,扩散作用保障CO₂高效传质,二者的协同调控是混合基质膜气体分离性能提升的关键,为高性能气体分离膜的设计与制备提供指导方向。

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