Professor Zhang jiepeng's team proposed a new concept of adsorption separation: intermediate size molecular sieve

Recently, Professor Zhang jiepeng of Sun Yat sen University published a paper (DOI: 10.1038 / s41563-019-0427-z) in nature materials, reported the new progress of adsorption and separation of coordination polymer porous materials, proposed and verified the concept of intermediate size molecular sieve The separation and purification of chemical mixture is a big energy consumption in chemical industry For example, as monomer raw materials of synthetic rubber, thermoplastic, resin, etc., styrene is mainly produced from catalytic cracking / dehydrogenation of ethylbenzene Because the reaction is limited by thermodynamics, there are a lot of unreacted ethylbenzene raw materials in the product, and some by-products such as benzene and toluene In industry, it is usually necessary to use several vacuum distillation / distillation columns to obtain styrene with polymerization purity (99.5%) It is expected that the energy consumption will be greatly reduced by changing the traditional separation technology such as distillation to adsorption separation based on porous materials Molecular sieves have uniform pore size of molecular level, which can only allow molecules smaller than the pore size to pass through, and can achieve ideal adsorption selectivity However, when there are many components with different sizes in the mixture, and the purification target is not the smallest component, the effect of molecular sieve will be greatly reduced For example, the size of styrene is between ethylbenzene and benzene / toluene, so it is impossible to obtain high-purity styrene by one-time adsorption with molecular sieve Professor Zhang jiepeng's research team has long been committed to the design, function and mechanism research of coordination polymer porous materials, and has developed "flexibility of dynamic control" (j.am.chem.soc 2008, 130, 6010; Natl SCI Rev 2018, 5, 907), "hydrophobic molecules trapped by hydrophilic channels" (Nat Commin 2015, 6, 8697), "controlling the molecular configuration of guest molecules to regulate adsorption selectivity" (Science 2017, 356, 1193), and other adsorption separation theories / concepts Recently, they also proposed a new adsorption and separation principle, called intermediate sized molecular sieve (ISMS), which can only absorb the target components of intermediate size in complex mixtures, and solve the major needs such as styrene separation and purification In order to achieve this special adsorption behavior, porous materials must have appropriate flexibility, so non-target components can be excluded by combining the thermodynamics principle (too small molecular adsorption energy is not enough to open the flexible framework) and the dynamics principle (too large molecular size exceeds the open pore window) They designed and synthesized maf-41, a kind of coordination polymer porous material with limited flexibility, and realized the super efficient purification of styrene (3300 selectivity) in the mixture of ethylbenzene, styrene, toluene and benzene Only one adsorption desorption cycle is needed to obtain the purity of 99.9% + phenylene Maf-41 also has super high thermal stability (500 ℃), water stability (boiling water, pH 3 ‒ 14) and super hydrophobic characteristics, which is conducive to practical application The comparison of traditional molecular sieve effect and middle size molecular sieve effect (source: Nature Materials) the Journal of nature materials published a news review paper by Professor Morris (http://dx.doi.org/10.1038/s41563-019-0437-x) at the same time, and highly praised this work The first author of the paper is Dr Zhou Dongdong (graduated from Zhongshan University in 2016, now a specially appointed associate researcher of Zhongshan University), and Professor Zhang jiepeng is the corresponding author The collaborators include Chen pin, an engineer at Sun Yat sen University's National Supercomputing Guangzhou center, Professor Du Yunfei and Dr Yan Hui This work has been strongly supported by Professor Chen Xiaoming, and supported by the National Natural Science Foundation of China, the local innovation team of the Pearl River talent program in Guangdong and the key regional R & D projects in Guangdong province.