Nanoparticle-templated mesoporous carbon

Zeolites are widely used as acid catalysts, especially in the petrochemical industry. Zeolites have several attractive properties such as high surface area, adjustable pore size, hydrophilicity, acidity, and high thermal and chemical stability. In order to fully benefit from the unique sorption and shape-selectivity effects in zeolite micropores in absence of diffusion limitation, the diffusion path length inside the zeolite particle should be very short, such as, e.g., in zeolite nanocrystals. An advantageous pore architecture for catalytic conversion consists of short micropores connected by meso- or macropore network [1]. Reported mesoporous materials obtained from zeolite precursor units as building blocks present a better thermal and hydrothermal stability but also a higher acidity when compared with amorphous mesoporous analogues [2-6]. Alternative approaches to introduce microporosity in walls of mesoporous materials are zeolitization of the walls under hydrothermal conditions and zeolite synthesis in the presence of carbon nanoparticles as templates to create mesopores inside the zeolite bodies [7,8]. 

Making use of constrained polymerisation of divinylbenzene on surfactant-modified colloid silica, Jang and Lim prepared carbon nanocapsules and mesocellular foams. Later, they reported that mesoporous carbons with highly uniform and tunable mesopores were fabricated by one-step vapour deposition polymerisation using colloidal silica nanoparticles as template and polyacrylonitrile as carbon precursor. Hampsey et al. recently reported the synthesis of spherical mesoporous carbons via an aerosol-based, one-step approach using colloidal silica particles and/or silicate clusters as template. ... 

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,... 

FIGURE 2.33 Proposed mechanism for the formation of nanopores in carbon using a colloidal silica nanoparticle template. (From Pang, J., Hu, Q., Wu, Z., Hampsey, J.E., He, J., and Lu, Y. Micropor Mesopor Mater lA 73-78, 2004. With permission.)... 

FIGURE 12.6 (a) Illustration of the preparation of mesoporous Au-mesoporous carbon and silica capsules using glucose as carbon source. (From Kim, J. Y. et al., Chemical Communications, 790, 2003.) (b) TEM images of Au nanoparticles in microporous carbon hollow spheres prepared from dopamine as the carbon precursor. The carbon spheres were as large as the Au-silica template spheres, approximately 400 nm in diameter, and the carbon walls were A nm thick. (From Liu, R. et al., Angewandte Chemie-Intemational Edition, 50, 6799, 2011.)... 

Novel Surface-Mediated Fabrication of Rh and RhPt Nanoparticles Using Mesoporous Templates in Supercritical Carbon Dioxide... 

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