Template carbonisation

Historically, the hard template carbonisation method was first reported by Knox et al. in 1986. They demonstrated the synthesis of graphitised porous carbons for liquid chromatography separation by impregnation of spherical porous silica gel with phenolic resin and subsequent carbonisation and removal of silica gel. Since the first reported use of template carbonisation, the method has been employed extensively to prepare ordered porous carbons. A variety of inorganic porous templates including zeo-... 

Indeed, the past ten years have witnessed rapid advances in using template carbonisation to produce ordered porous carbon materials, ranging from microporous to mesoporous and macroporous carbons. The template carbonisation method has thus been regarded as one of the most effective approaches to prepare porous carbon materials with desirable physical and chemical properties. It has, therefore, opened up new opportunities in making novel porous materials for a wide range of applications. 

Lee, K.T. and Oh, S.M. (2002). Novel synthesis of porous carbons with tunable pore size by surfactant-templated sol-gel process and carbonisation. Chem. Commun., 22, 2722—3. 

The disadvantage of traditional hard template synthesis of porous carbon is that it usually involves several steps starting with the preparation of a mesoporous silica/surfactant mesophase followed by calcination to remove the surfactant (to generate the mesoporous sUica hard template), introduction of carbon precursor into the mesoporous siUca, carbonisation of the carbon precursor and finally silica etching (i.e. washing with HF or NaOH) to generate the mesoporous carbon. Therefore, recently there have been some attempts to prepare mesoporous carbon via more direct methods involving fewer steps. 

Yoon etal)- reported the synthesis of mesoporous carbon using as-synthesised MCM-48 silica/surfactant mesophase as the template, followed by introduction of carbon precursor (divinylbenzene), carbonisation and removal of silica. Hyeon and co-workers " reported the synthesis of mesoporous carbon by the carbonisation of composites containing silica, P123 triblock copolymer and phenol resin, followed by removal of silica. The synthesis was achieved by treating the as-synthesised silica/triblock copolymer nanocomposite with sulfuric acid to crosslink the triblock copolymers followed by carbonisation. " Kim et al. reported the synthesis of carbon nanotubes using PI 23 surfactant inside mesoporous silica, although ordered arrays of carbon nanotubes were not observed.Kawashima et al. synthesised mesoporous carbon via copolymerisation of tetraethoxysilane (TEOS) and furfuryl alcohol. 

Hu et al. have synthesised ordered mesoporous and macroporous carbon monoliths by template method using silica monoliths as template. In this preparation, the mesophase pitch was used as the carbon precursor [54]. The silica monolith templates were filled with a 10 wt.% solution of mesophase pitch in tetrahydrofuran solvent and then carbonised at different temperatures. The physical characteristics of these various mesoporous and macro-porous carbon are presented in Table 7.8, which demonstrates these carbons have more prominent graphitic structures as the carbonisation temperature increases. SEM images of the carbon monoliths obtained at carbonisation temperature of 700°C and 2500°C are shown in Figure 7.59. 

Duke, M.C., da Costa, JC. D., Lu, G. Q., Petch, M. and Gray, P. (2004b) Carbonised template molecular sieve silica membranes in fuel processing systems permeation, hydrostability and regeneration. Journal of Membrane Science, 241, 325-333. 

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