Microporous Metal-Organic Framework Materials for Gas Separation

Gas is one of the fundamental states of matter, which is usually invisible, highly dispersed, and of low concentration; it easily creates mixtures and is thus difficult to handle, as exemplified by many important chemical commodities. Ten to fifteen percent of the world’s energy production has been used for separation and purification of industrial commodities through energy-intensive processes such as distillation. Adsorptive separation based on porous materials is a promising technology to lower the separation energy use. Compared to conventional porous materials such as activated carbon and zeolites, metal-organic frameworks (MOFs) represent a unique type of material with exceptional porosity, high modularity, and diverse functionality, showing great promise in addressing important gas separations. This review not only provides the updated status of MOFs for gas separation but also directs research endeavors to pursue better MOFs for practical applications. Gas separation is a very important industrial process for manufacturing chemicals, fuels, plastics, and polymers but is also energy intensive through the traditional cryogenic distillations. Adsorptive gas separation by porous materials can potentially fulfill the energy-efficient separation economy. Metal-organic frameworks (MOFs), a new generation of porous materials, have been demonstrated for their promise in addressing important gas separations. In this review, we outline the uniqueness and basic design principles of MOF chemistry for gas separation in terms of their specific pore chemistry and molecular recognition. The finely tuned micropores for the high sieving effects and immobilized functional sites on pore surfaces for specific recognition of gas molecules have enabled us to develop a variety of microporous MOFs for many gas separations with both high separation selectivity and productivity. We highlight the major progress and achievements in this very important topic, which will further facilitate the extensive research endeavors and promote their industrial implementation for gas separation. Gas separation is a very important industrial process for manufacturing chemicals, fuels, plastics, and polymers but is also energy intensive through the traditional cryogenic distillations. Adsorptive gas separation by porous materials can potentially fulfill the energy-efficient separation economy. Metal-organic frameworks (MOFs), a new generation of porous materials, have been demonstrated for their promise in addressing important gas separations. In this review, we outline the uniqueness and basic design principles of MOF chemistry for gas separation in terms of their specific pore chemistry and molecular recognition. The finely tuned micropores for the high sieving effects and immobilized functional sites on pore surfaces for specific recognition of gas molecules have enabled us to develop a variety of microporous MOFs for many gas separations with both high separation selectivity and productivity. We highlight the major progress and achievements in this very important topic, which will further facilitate the extensive research endeavors and promote their industrial implementation for gas separation.