Ordered mesoporous carbon pore-size distribution

FT-IR spectra are obtained from mesoporous silica (MCM-41) dispersed in potassium bromide (KBr) pellets (the mass ratio of MCM-41 over KBr is in the 10 range). MCM-41 is obtained by a sol-gel process. It is an ordered mesoporous silica with a hexagonal array of one-dimensional pores and a narrow pore-size distribution of about four nanometers. The glass was baked at 140°C for one hour and then at 400°C for another hour to remove any carbon contaminates. 

Ordered mesoporous carbons (OMCs) are new carbon materials that were developed over the last ten years. Their mesopores have a defined width with a very narrow pore size distribution. This sets them aside from older nanoporous carbons, such as activated carbons or activated carbon fibers. The last two classes of carbons are produced from various carbon-containing materials by carbonization followed by partial oxidation (activation). To a certain degree, the pore structure of these materials can be controlled by the carbonization and activation conditions. However, it is not possible to produce purely mesoporous activated carbons or activated carbon fibers. Furthermore, these materials generally exhibit a broad pore size distribution [1, 2]. 

The values of the mesopore volumes and radii and the value of the fiactal dimension, are convergent, as for the size order, with the corresponding values obtained during studies of the structure AI2O3 [64], Values of pore volume near 2 nm have the highest intensity in this curve. The concentration of mesopores decreases with increase of their radius. The observed shape of the pore-size distribution curve is typical for most industrial mesoporous adsorbents. For example, this shape is similar to that found from low-temperature nitrogen adsorption isotherms on various activated carbons by using the Dollimore-Heal method [63]. 

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... 

OMC carbons obtained from replication of structured mesoporous silicas show a narrow pore size distribution, but with mesopores smaller (< 15 nm) than those obtained from colloidal replication. PtRu nanoparticles supported on ordered mesoporous carbon CMK-3 were analyzed by Din et al. [63] Although a good nanoparticle dispersion was obtained, the catalyst synthesized showed a worse performance than nanoparticles supported on Vulcan XC-72 for methanol oxidation. 

Hierarchically ordered mesoporous carbons (HOMC) are attractive as a support for fuel cell applications because of their interconnected bimodal pore-size distribution. Both pore systems can be mesoporous or one can be mesoporous while other can be macroporous. While a mesoporous pore structure imparts high surface area and uniform distribution of catalyst particles, macropores provide efficient mass transfer. Of course, the interconnectivity between pores has a significant role in realizing the advantages of both pore stmctures. Also, a novel feature about these structures is that the two pore structures can be adjusted independently, allowing for good control over their porosity [73, 74]. Like OMC, controllable pore structure, and carbon microstracture and surface chemistry, makes them an attractive support for fuel cell catalysis. Fang et al. have shown that Pt on hollow... 

OMCs have highly ordered mesoporous structures with very narrow pore size distributions. Uniform and small metal catalysts can be easily prepared even using impregnation method. Ordered mesoporous carbons are one type of... 

Recently, attention has been paid to porous carbon materials, owing to their large surface area, large pore volume, chemical inertness, and electrical conducting properties. Porous carbon materials with controlled architecture, morphology, and relatively narrow pore size distribution are usually prepared by a templating (hard or soft) method followed by carbonization processes. The main synthetic way to produce ordered mesoporous carbons relies on the use of ordered mesoporous silica with interconnected pore structures as a hard template. This synthetic route (see Fig. 16.6 for the hard template route) requires (1) preparation of... 

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