Microporous carbon materials

As it can be seen in Figure 4.3, the characteristic curve for N2 superimposes over that for C02 up to a value of (A/p)2 lower than about 400 (kJ/mol)2, confirming what was previously explained. From this value, a large downward deviation is observed in the N2 characteristic curve. This behavior has been observed with other microporous carbon materials and, in fact, it is a common problematic feature of the characteristic curves for N2 adsorption in microporous carbons and hence, a limitation of its use in such low relative pressures (i.e., from 10-3 to 10-7) [10,11,17], This downward deviation... 

Microporous carbon materials arc widely used in adsorption processes for separating gaseous and liquid components [1], Fossil peat and coal [2], polymers and resins [3], wood pulp and other plant raw materials [4] are widely used as raw to produce microporous carbon-containing materials. 

As an example of the above statement. Fig. 17.3 contains the Nj adsorption isotherms for powder AC vidth different adsorption capacities [3]. These isotherms, compared with those in Figs. 17.1 and 17.2, clearly demonstrate that the adsorption isotherms do not permit neither to distinguish the ACF from the AC nor to deduce differences in the pore size distribution. However, the unique fiber shape and porous structure of the ACF are advantages that permit to deepen into the fundamentals of adsorption in microporous solids [31]. ACFs are essentially microporous materials [13, 31], with sht-shaped pores and a quite uniform pore size distribution [42, 43]. Thus, they have simpler structures than ordinary granulated ACs [31] and can be considered as model microporous carbon materials. For this reason, important contributions to the understanding of adsorption in microporous solids for the assessment of pore size distribution have been made using ACF [31, 33, 34, 39, 42-46], which merit to be reviewed. 

Several reviews covering the synthesis, properties and applications of porous carbons, especially mesoporous carbon materials, can be found in the literature. In this chapter, we summarise the recent developments in the synthesis and characterisation of templated porous carbon materials. Particular attention is paid to the synthesis of structurally ordered porous carbon materials with narrow pore size distribution via both hard and soft template methods. We especially emphasise those so-called breakthroughs in the preparation of porous carbon materials. The chapter is divided into three sections according to the pore size of carbon materials we first consider the synthesis of microporous carbon materials using zeolites and clays as hard template, then summarise the preparation of mesoporous carbon materials via both hard template and self-assembly... 

MICROPOROUS CARBON MATERIALS 4.2.1 Zeolites as Hard Template... 

Shen W, He Y, Zhang S, Li J, Fan W (2012) Yeast-based microporous carbon materials for carbon dioxide capture. ChemSusChem 5 1274-1279... 

Zeolites are microporous crystalline aluminosilicates with a channel-like or cagelike pore structure with pore-opening sizes in the range of 0.3 to 1.5 nm [13]. The spatially periodic pore structure and well-defined nanospaces of zeolites offer opportunities to control the nanostructure and morphology of microporous carbon materials at the nanometer level. As schematically illustrated in Figure 2.1, zeolite pores can be filled wifh a carbon precursor such as furfuryl alcohol (FA). After a proper treatment, followed by removal of the zeolite framework, a carbon nanostructure with pores replicated from the zeolite framework is obtained. Over the past decade, many zeolite templates (e.g., zeolite Y, zeolite (3, and ZSM-5) and carbon precursors (e.g., FA, phenol-formaldehyde, and sucrose) have been... 

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