Covalent Organic Frameworks COFs

For CH4 storage, the highest values were observed for COF-103 (175 mg g ) and COF-102 (187 mg g ), and were comparable to MOFs (MOF-210 220 mg g ). Theoretical simulation studies predict the strong interaction of 

COFs with boronate-ester linkages show effective ammonia sorption due to the Lewis acid-base interaction. Among them, COF-10 exhibits an uptake capacity of 15 molkg at 298 K and 1 bar. COFs can be recycled several times without much loss of activity. 

CMPs exhibit enthalpies of adsorption for hydrogen up to 18 kj mol . Such a high value is indicative of reversible hydrogen storage at room temperature. CMP-0 demonstrated an H2 capacity of 1.4 wt% at 77 K and 1 bar. The introduction of Pd nanoparticles into CMP-0 enhances its capacity. Incorporation of acid functionalities into the CMP material decreases the CO2 adsorption capacity more than for the non-functionalized CMP analogues.  

JUC-Z5 and JUC-Z4 showed reversible methane adsorption isotherms. CH4 uptake of JUC-Z5 was 16 cm g while that of JUC-Z4 was 20 cm g and that of PAF-1 was 18 cm g at 273 K/760 mm Hg. In spite of the much lower specific surface areas of JUC-Z5 and JUC-Z4 compared to PAF-1, the strong interactions between CH4 and the phosphorus (P) moieties make JUC-Z5 and JUC-Z4 comparable with PAF-1 in the case of methane uptake. 

Key features that make JUC-Z5 and JUC-Z4 very effective for CO2 capture are the excellent physico-chemical stability with well-defined micropore sizes (pore size lnm). For JUC-Z5, JUC-Z4 and PAF-1, the CO2 storage capacities at 273 K and 760mmHg are 56, 59 and 46 cm g respectively, while the values are 38, 34 and 25 cm g at 298 K and 1 bar. 

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Figure 4.6 Illustration of a covalent organic framework (COF) material composed of hexahydroxytriphenylene and either tetra(4-dihydroxyborylphenyl)methane or silane crosslinking moieties. (From Reference [56] with permission.)...

Very recently covalent organic frameworks (COFs) 33 have been designed and synthesized by simply condensation of phenyl diboronic acid with hexahy-droxytriphenylene (67) (Fig. 14). Material 33 is composed of expanded porous graphitic layers, with pore sizes up to 27 A. Covalent organic framework (33) is thermally stable till 500-600°C and have a surface area of 1590 m g. This exceeds the highest reported surface area of 1300 m g for macroporous ordered silica. 

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs)... 

Covalent organic frameworks (COFs Sect. 3.1) 711-4,210 0.32-1.66" High thermeil stability porosity sensitive to air for B-conteiining COFs Highest MOP surface areas crystalline tunable pores [14, 20, 67]... 

Figure 1.9 ThevariationofH2adsorbed(wt%)atsaturationat77KwithBET (a)and Langmuir surface area (b) for porous MOFs, carbons, zeolites, silicas, polymers, and covalent organic frameworks (COFs). Reprinted with permission from K.M. Thomas, Dalton Trans., 9,1487-1505. Copyright (2009) Royal Society of Chemistry...

Ding S-Y, Wang W (2013) Covalent organic frameworks (COFs) from design to applications. Chem Soc Rev 42 548-568... 

Microporous materials have important potential applications for many fields of science, including gas storage, heterogeneous catalysis and chemical separations. Examples of microporous networked materials include metal organic frameworks (MOFs), " covalent organic frameworks (COFs), zeolites and microporous organic polymers (MOPs). ... 

Porous organic frameworks (POFs), such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), conjugated micro-porous polymers (CMPs), ° polymers of intrinsic microporosity (PIMs), crystalline triazine-based organic frameworks (CTFs), hyper-crosslinked... 

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. 

Figure 8.4 Covalent organic framework (COF) structure based on a condensation process followed by boroxine monomer extraction to give a 3D boroxine framework. (Reproduced from ref. 18 with the permission of Elsevier.)...

The separation factor of these organic polymer membranes is typically located in a moderate range, of around 5 and 10, but rarely higher than 20. As a rule of thumb and proven by recent publications, the membrane selectivity can be approximated as the product of the adsorption selectivity and diffusion selectivity [2]. This chapter provides a wealth of information on diffusion inside micro- and mesoporous structures using concepts and ideas that originate from Maxwell and Stefan. A molecular-level understanding of diffusion in a variety of materials such as zeolites, MOFs, covalent organic frameworks (COFs), carbon nanotubes, and cylindrical silica pores is provided with the aid of extensive data sets of molecular... 

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