Gas Adsorption and Separation

Shimizu and coworkers [112] tested their bisurea nanotube 33b-tube by CO2 adsorption. The CO2 uptake was 71.5 cm g at 0.5 atm. and -78 °C and the calculated Brunauer-Emmett-Teller (BET) surface area was 341 m g comparable to those of microporous zeolites. Unlike the reliable bisurea system, the predictable assemble of molecules into solids is still very difficult. Therefore, McKeown and co workers [113] proposed to search the existing compounds. 

Rational construction has also been achieved. Champness, Schroder and coworkers [117] designed a rigid multifunctional and multidirectional unit 84, which self-assembled to a 3D framework SOF-1 with pyridyl decorated channels. 

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Li J-R, Kuppler RJ, Zhou H-C (2009) Selective gas adsorption and separation in metal-organic frameworks. Chem Soc Rev 38(5) 1477-1504... 

Selective gas adsorption and separation in flexible MOFs is considerably more complicated than that in their rigid counterparts. Due to the high degree of cooperativity in these systems (e.g. in inducing framework deformation, the uptake of one guest can dramatically alter the uptake of another), comparison of adsorption isotherms of pure gases is of limited use and competitive measurements are essential if separation capabilities are to be determined. Due to the fact that such measurements remain very rare, and that structural information is often unavailable for the mixed-sorbed phases, only limited understandings of gas separations in flexible MOFs currently exist. 

The regular crystal structures of microporous solids have led, directly and indirectly, to their widespread study and application. The starting point in understanding their behaviour is the architecture of the repeat unit, or unit cell, which controls their properties. The well-defined pore size permits discrimination between molecules (and transition states in catalytic reactions) to better than 0.1 A activities for oxidation and solid acid catalysis are determined by the structural constraints on the local environments of framework cations and protons within the structure and the regular distribution of extra-framework, charge-balancing cations is responsible for cation exchange and gas adsorption and separation behaviour. 

Li JR, Ma YG, McCarthy MC et al (2011) Carbon dioxide capture-related gas adsorption and separation in metal-organic frameworks. Coord Chem Rev 255 1791-1823... 

In this final section of this report, we would like to draw a structure property relationship in the FMOF series. Now, looking through the applications of the FMOFs, many of them has been exploited for gas adsorption, storage, gas/hydrocarbon separation, and so on. In this regard, depending on the end applications of these MOFs, they are divided into two parts (i) FMOFs for gas adsorption and separation and (ii) FMOFs for hydrocarbon uptake. 

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