Synthesis, properties, and application of zeolite-templated carbons

Abstract

Zeolite-templated carbons (ZTCs) are microporous carbon materials synthesized by the carbon replication of microporous zeolites. Well-made ZTCs can exhibit ordered 3-dimensional microporous structures with large surface areas (> 2800 m2 g-1), micropore volumes (> 1.0 cm3 g-1), and narrow micropore size distributions. Furthermore, ZTCs have a unique carbon structure consisting of 3-dimensionally connected graphene layer, resulting in high electrical conductivity and abundant presence of edge sites in carbon frameworks. In spite of their high potential to various application due to unique-pore structure, ZTCs have not been used in real industries yet, compared to other commercialized carbons (e.g., carbon nanotube). One possible reason is that the mass production of highly-ordered ZTCs is quite challenging, because a carbon deposition within micropore of zeolite templates is sensitive to synthesis conditions (e.g., carbon precursors, synthesis temperature, and reactor design). In this study, I have successfully synthesized high-quality ZTCs in a large scale (100 g scale) by choosing an appropriate synthesis conditions. The key point is preventing the formation of external carbon layers on zeolite surfaces during the synthesis, by inducing the synthesis conditions as uniform mass/heat transfer. The resultant ZTCs showed highly-ordered microporous structures with large surface area (> 3000 m2 g-1) and micropore volume (> 1.1 cm3 g-1). Furthermore, I demonstrated that the micropore diameter of ZTCs can be tailored by a post-synthesis thermal treatment in the range of 1.1–1.5 nm. This is attributed to systematic contraction of ZTC frameworks. Using this system, I studied the effects of the carbon microporous structure on CH4 adsorption. With additional study about relationship between carbon morphologies and adsorbent packing densities, I synthesized ZTCs with highly promising volumetric CH4 storage capacity as 210 cm3STP cm-3.