Professor Wang Haihui's team of South China University of technology has made new progress in fine tuning the pore size of rigid zif-8 membrane with electric driven mixed ligand strategy

Since the 21st century, due to the increasing consumption of non renewable energy such as coal, oil and natural gas and the decreasing storage, people are increasingly aware of the need to find a new renewable clean energy to curb the further expansion of the energy crisis As a new clean energy, methane has the highest ratio of hydrogen to carbon in all hydrocarbons, and can be used in power generation, cooking, heat source and fuel Renewable energy biogas contains a lot of methane, but at the same time, it also contains a lot of carbon dioxide Therefore, how to remove carbon dioxide from biogas to obtain high-purity methane is the main problem and challenge we are facing The traditional method is to remove carbon dioxide and purify methane by adsorption or ammonia solution absorption, but the operation cost is high because the adsorbent / solvent needs to be recycled As a promising separation technology, membrane separation has attracted more and more attention because of its advantages of low energy consumption, high efficiency and easy operation In particular, ZIF series of metal organic framework films have been widely used in separation field because of their good thermal stability and high porosity The pore size of zif-8 is just between the molecular size of carbon dioxide and methane, so it can be separated efficiently in theory Recently, Professor Wang Haihui's team of South China University of technology has used the fast current drive method to prepare the mixed ligand zif-7 X-8 membrane with relative rigidity and continuously adjustable pore size, which shows superior separation performance of CO2 / CH4 The results of XRD show that the zif-7 X-8 film has a rigid phase structure In this work, the separation factor of zif-722-8 membrane for CO2 / CH4 is as high as 25, which is an order of magnitude higher than that of traditional zif-8 membrane, and has long-term temperature stability This dual strategy of "rigidity and shrinkage" simultaneously can be further applied to the preparation of other flexible MOF membranes to improve the screening performance of gas molecules The research results were published in Angel W chem Int ed (angel W chem Int ed 2019, 58, 327-331) and selected as VIP articles The first author of this research work is Hou Qianqian, a postgraduate student, and the corresponding authors are Professor Wang Haihui, researcher Wei Yanying and Professor J ü rgencaro (source: angelw Chem Int ed.)