Thermal stability mesoporous MOFs

From natural zeolites to the recently discovered meso- and macro-porous materials, the ordered porous frameworks are all constructed by inorganic species. However, in the past ten years, a new family of porous compounds composed of metal-organic frameworks (MOFs) has attracted enormous attention. The main reason is that the poor thermal and chemical stability of MOFs has been somewhat improved. In addition, the discovery of some advantages of MOFs that are lacking in molecular sieves and mesoporous materials has also stimulated the research on MOFs. 

The definition for catalytic purposes of a zeolite reads as follows a crystalline material with micropores and cation-exchange capacity that is insoluble in water and common organic solvents and has sufficient thermal stability that allows removal of all pore-filling agents present in the as-synthesized materials. This definition is narrower than that of the IZA Constitution, which includes mesoporous solids, metal organic frameworks (MOFs), cationic and anionic clays [3]. 

The diversity of ordered porous solids increases at an astonishing rate, particularly among the readily crystallised MOFs, and continues to olfer novel materials properties. There is no obvious barrier to the synthesis of a myriad of new zeolite, zeotype or hybrid structures. Challenges remain, however. For zeolitic aluminosilicates, the 10 A pore size restriction remains an important barrier, and an enantiomerically pure zeolite is still out of reach. For nonsilicate crystalline microporous solids, thermal and hydrothermal stability, rather than framework geometry, limit their applicability, since fully crystalline germanates and carboxylates with pores in the mesoporous range now exist, and these solids have enormous specific surface areas. In these hybrid solids the ability to choose chirality in the building units indicates that it will be possible to prepare these in chiral form the first examples have already been prepared. 

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