Qi Kai, Yu Junmei, Gao Yifei, Shi Lijuan, Yi Qun, Li Xuelian, Zeng Jian, Gao Longsheng, Gao Lili. (2024). Ultrathin and Self-Supporting MOF/COF-Based Composite Membranes for Hydrogen Separation and Purification from Coke Oven Gas. Langmuir. (SCI, 二区/Q2, IF=3.7)
DOI:10.1021/acs.langmuir.4c01368
Abstract
Coke oven gas (COG) is considered to be one of the most likely raw materials for large-scale H2 production in the near or medium term,with membrane separation technologies standing out from traditional technologies due to their less energy-intensive structures as well as simple operation and occupation.Based on the“MOF-in/on-COF” pore modification strategy, the COF membrane (named the PBD membrane) and ZIF-67 were used as assembly elements to design advanced molecular sieving membranes for hydrogen separation. The composition and microstructure of membranes before and after ZIF-67 loading as well as ZIF-67-in-PBD membranes under different preparation conditions (metal ion concentration,metal-ligand ratio, and reaction time) were investigated by various characterizations to reveal the synthesis regularity and microstructure regulation. Furthermore, H2/CH4 separation performances and separation mechanisms were also analyzed and compared.Finally,a dense,continuous,ultrathin,and self-supporting ZIF-67-in-PBD membrane with a Co2+ concentration of 0.02 mol/L,a metal−ligand ratio of 1:4,and a reaction time of 6 hexhibited the largest specific surface area,micropore proportion,and the best H2/CH4 separation selectivity (α=33.48) ,which was significantly higher than the Robeson upper limit and was in a leading position among reported MOF membranes.The separation mechanism was mainly size screening, and adsorption selectivity also contributed a little.
焦炉煤气（COG）被认为是近期或中期最有可能大规模生产氢气的原料之一，而膜分离技术因其结构能耗低、操作和占用简单而在传统技术中脱颖而出。本文基于“MOF-in/on-COF”孔修饰策略，以COF膜（命名为PBD膜）和ZIF-67为组装元件，设计了先进的氢分离分子筛膜。通过各种表征研究了负载ZIF-67前后膜的组成和微观结构，以及不同制备条件（金属离子浓度、金属配体比和反应时间）下ZIF-67-in- pbd膜的合成规律和微观结构规律。此外，还对H2/CH4的分离性能和分离机理进行了分析和比较。结果表明，在Co2浓度为0.02 mol/L、金属配体比为1:4、反应时间为6 h的条件下，致密、连续、超薄、自支撑的ZIF-67-in-PBD膜具有最大的比表面积、微孔比例和最佳的H2/CH4分离选择性（α=33.48），显著高于Robeson上限，在已报道的MOF膜中处于领先地位。分离机理主要以粒度筛选为主，吸附选择性也起一定作用。
