| Over the past few decades, the development of membrane materials both in research-oriented and industrial applications attracts people much interests. The membrane just seems like a barrier, it can selectively control some materials to pass through and make other substances not, as a result, we can use the membrane to separation the mixtures. Compared with the traditional separation methd, the separation based membrane has the advantage of energy saving and efficiency.Although for a long time, the development and application of the membrane is document by the polymer membrane, because it has the disadvantages of short-life,low working temperature, lower chemical stability and selectivity, people need to explore some new membrane materials that has stable performance and are more conductive to separation. MOFs become the excellent candidates of membrane fabrication, due them has diversity structures, uniform pore size, permanent porosity,high thermal and chemical stability. As is known to all, the membrane separation is mainly based on the molecular size sieve, and it also can separate some materials that can react with the membrane through the method of adsorption and diffusion. The membrane based MOFs has developed quickly, because we can control the pore size easily by changing the metal ions and organic ligands and we can also modified the surface of their pores through some approaches. ZIFs, subfamily of the MOF materials, have higher thermal and chemical stability than MOFs and become one of the members of porous materials that used to fabrication membrane quckly. Although more and more MOF membrane has been synthesized successfully, how make the membrane has higher gas permeability as well as the higher selectivity also has much challenge.As another porous material that emerged recently, covalent organic framework(COF) is formed by some lightweight elements(C, N, O, B) through covalent bond constituted the network skeleton that has long range order. This material also has some advantages, like high stability, permanent porosity, high surface area and the lowest density in the porous materials. COF is also the preface materials that canapply in the gas adsorption and gas store like MOF materials, in addition, it also can be used for drug release and photoelectric. As we know, there is few reports about the membrane based COF that can be used for gas or liquid separation.In this article, we firstly synthesize the Zn2(bdc)2(dabco) membrane that can be used for gas separation on the SiO2 disk modified by PANI. In the mixture H2/CO2 separation, the membrane show the favourable property, the H2/CO2 selectivity is 6.97 and the permeance of H2 is 7.88×10-7mol·m-2·s-1·Pa-1 on the membrane. We also synthesize the ZIF-8 membrane on the same support, and the mixture H2/CO2 selectivity is 9.10 and the permeance of H2 is 6.47×10-7molm-2s-1Pa-1 on the ZIF-8membrane. This gas separation properties is much better than the ZIF-8 membrane reported before. Moreover, we firstly fabricate one compact and continuous COF membrane that has excellent gas separation properties on the support modified by the PANI successfully, the mixture H2/CO2 selectivity is 6.01, and the permeance of the H2 is 8.11×10-7molm-2s-1Pa-1.What is more, we firstly synthesize two types of COF/MOF composite membranes, COF-300/Zn2(bdc)2(dabco) and COF-300/ZIF-8composite membrane, all of them show the much more excellent properties than the individual MOF membrane and COF membrane. The selectivity of mixture H2/CO2 is12.63 and the permeance of H2 is 4.56×10-7molm-2s-1Pa-1 on the COF-300/Zn2(bdc)2(dabco) composite membrane. The selectivity of mixture H2/CO2 is 13.53 and the permeance of H2 is 3.58×10-7molm-2s-1Pa-1 on the COF-300/ZIF-8composite membrane. |
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