Zeolite-templated microporous carbons

FIGURE 3.25 Diffusion of electrolyte ions into the pores of a conventional activated carbon and the ordered microporous carbon prepared using the zeolite template. 

Ania, C.O., Khomenko, V., Raymundo-Pinero, E., Parra, J.B., and Beguin, F. The large electrochemical performance of microporous doped carbon obtained by using a zeolite template. Adv. Fund. Mat. 17, 2007 1828-1836. 

Zeolites were already employed as templates in the synthesis of microporous carbon with ordered structures.[247] The discovery of ordered mesoporous silica materials opened new opportunities in the synthesis of periodic carbon structures using the templating approach. By employing mesoporous silica structures as hard templates, ordered mesoporous carbon replicas have been synthesized from a nanocasting strategy. The synthesis is quite tedious and involves two main steps (i) Preparation and calcination of the silica mesophase, and (ii) filling the silica pore system by a carbon precursor, followed by the carbonization and selective removal of the silica framework. 

J. Rodriguez-Mirasol, T. Cordero, L.R. Radovic, and J.J. Rodriguez, Structural and Textural Properties of Pyrolytic Carbon Formed within a Microporous Zeolite Template. Chem. Mater., 1998, 10, 550-558. 

Paredes, J.I., Martinez-Alonso, A., Yamazaki, T., et al. (2005). Structural investigation of zeolite-templated, ordered microporous carbon by scanning tunneling microscopy and Raman spectroscopy. Langmuir, 21, 8817-23. 

Rodriguez-Mirasol, J., Cordero, T., Radovic, L.R., and Rodriguez, J.J. (1998). Structural and textural properties of pyrolytic carbon formed within a microporous zeolite template. Chem. Mater., 10, 550-8. 

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... 

In order to improve the structural ordering of zeolite-templated carbons, Ma et al. have investigated systematically the synthesis of microporous carbons using zeolite Y as hard template. They used a two-step method to prepare an ordered, microporous carbon with high surface area, which retained the structural regularity of zeolite Y by filling as much carbon precursor as possible into the zeolite pores so as to prevent any subsequent partial collapse of the resulting carbon framework. In the... 

Figure 4.2 XRD patterns of (a) zeolite Y and (b) zeolite Y-templated carbon liberated from the carbon/zeolite Y composite. Reprinted with permission from Z.X. Ma, T. Kyotani and A. Tomita, Chem. Comm, Preparation of a high surface area microporous carbon having the structural regularity of Y zeolite. Issue 23,2365-2366. Copyright (2000) RSC Publishing...

Figure 4.3 HRTEM image and corresponding diffraction pattern (inset) of zeolite Y-templated ordered microporous carbon.Reprinted with permission from Z.X. Ma, T. Kyotani, Z. Liu, O. Terasaki and A. Tomita, Chem. Mater., Very High Surface Area Microporous Carbon with a Three-Dimensional Nano-Array Structure Synthesis and its Molecular Structure. 13, 4413. Copyright (2001) American Chemical Society...

In this chapter, we provide an overview of the recent research and development in the preparation, characterization, and application of novel porous carbons using both the endotemplate and the exotemplate methods. A discussion of zeolite templates for microporous carbons is followed by that of ordered mesoporous silica templates for OMCs, nanoparticle templates for mesoporous carbons, sol-gel processed porous carbons, self-assembled colloidal crystal templates for ordered macroporous carbons, and colloidal sphere templates for hollow carbon spheres, as well as other templating approaches to preparing carbon nanostructures. Then,... 

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... 

Kyotani and coworkers [81] systematically demonstrated the preparation of micro-porous carbons using zeolite templates, whereas early studies [82-84] described the pyrolysis of carbon precursors to make carbon materials in the presence of zeolites. Subsequently, Mallouk and coworkers [85] employed zeolites Y, L, and P as templates to prepare microporous carbons with a specific surface area as high as 1580 m /g. It was reported that the zeolite template has a direct relationship with the structural and topological properties of the resultant carbon. Rodri-guez-Mirasol et al. [71] described the preparation of microporous carbons with a wide distribution of pore sizes, well-developed mesoporosity, and high adsorption capacity. Zeolite Y was used as template, and a chemical vapor infiltration method was employed to deposit carbon in the template pores. It was found that the apparent surface area of the resultant carbons increased with increasing deposition temperatures. Meyers et al. [72] synthesized porous carbon materials with a surface area of about 1000 m /g using zeolites Y, p, and ZSM-5 as templates and acrylonitrile, FA, pyrene, and vinyl acetate as carbon precursors. The template-encapsulated carbon precursors were pyrolyzed at 600 C, and the resultant materials were observed to be composed of disordered carbon arrays. 

Barata-Rodrigues et al. [73] reported that the CVD technique does not help improve the structural regularity of a zeolite-templated carbon. We indeed found that, when wet impregnation is followed by a CVD treatment, the XRD peak at 6° 20 can be observed, indicating the appearance of an ordered pore structure [75]. However, this XRD peak cannot be resolved for the carbon prepared without using the CVD technique [74]. An alternative route to the synthesis of ordered microporous carbons by using zeolite Y as template has also been described [88]. In addition, the use of other zeolite templates such as EMC-2 to improve structural regularity of replicated microporous carbons has been demonstrated... 

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