Zeolite imidazolate framework material

The presence of water vapour will define which materials can be used based on their hydrolytic stability. As an example metal-organic frameworks (MOFs) and covalent organic framework (COFs) are crystalline microporous materials which can exhibit exceptionally high surface areas and gas sorption capacities and, as such, have been proposed as potential materials for CCS. However, some of these materials can be unstable in the presence of moisture. The IRMOF series and the more recently produced COF materials are particularly unstable (e.g., loss of porosity at room temperature in air). Clearly, materials of this type would be unsuitable for CCS application. If such materials are to be used, more stable types are required for example, one class of MOF known as zeolitic imidazole frameworks (ZIFs) are reported to have greatly improved hydrolytic stability. 

It turns out that compressing MOF materials to very high pressures gives results that are much more significant than just academic curiosity. Similar experiments performed on the zeolitic imidazolate framework known as ZIF-8 [(Zn(meim)2], meim = 2-methylimidazolate again show expansion at modest pressures as the PTM is squeezed into the cavities, but at 1.5 GPa the material undergoes a phase transition... 

Figure 2 Different approaches to improve polymeric membrane materials. Notes MOF = metal-organic frameworks ZIF = zeolitic imidazolate frameworks CNT = carbon nanotubes PLO = porous layer oxides. (Reproduced from Ref. 36, MDPI AG (Basel, Switzerland) 2012.)...

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