| Porous materials are developing at an astonishing speed due to their wide variety of applications. Many new, attractive but more challenging appications involving porous materials have merely begun. Trizines, exspecially melamines, with good stability and high N content have proven their great potential in materials chemistry. The effective design and synthesis of new functional porous materials from simple, cheap and readily available molecular monomer (i.e. melamine) remains a challenging and important line of research in materials chemistry. Here, we prepared several novel N-enrich porous materials using melamine as raw materials. The main researches were as follows:1. Based on a facile catalyst-free process using Schiff base chemistry, here, highly cross-linked porous aminal networks were rapidly prepared via microwave irradiation using melamine and terephthalaldeyde as monomers. The polymer networks contained as high as 50 wt% of nitrogen, in situ doped with sulfur, with specific surface areas of up to 301 m2/g. Adsorption kinetics and isotherm studies demonstrated that the Hg2+ removal by these polymers was extremely rapid and highly efficient. Particularly these materials also exhibited an excellent selectivity towards Hg2+ over other interfering ions. Studies by FT-IR, Raman and XPS spectra showed that all the N-containing groups as well as S-containing groups on the polymer matrix could be responsible for the Hg adsorption, through the mechanism of surface complexation.2. A simple method for the shape-controlled synthesis of 3D N-doped graphitic carbons (i.e. nanoporous frameworks, hollow nanospheres) has been developed using cheap, readily available nano-CaCO3 (ca.￥3000/ton) as template, and MF resin as carbon precursor. Carbon powders or monoliths can be prepared through two different synthetic routes. For the first time, we found that the nano-CaCO3 was a mild graphitization catalyst to prepare N-doped graphitic carbon at moderate temperatures (1000-1300℃). Both the morphology and the degree of graphitization of the resulting carbons can be easily controlled by simply varying the template amount and carbonized temperature. The obtained carbons with abundant mesopores and macropores contained as high as 20.9 wt % of N, with specific surface areas and pore volume up to 834 m2/g and 5.6 cm/g, respectively.3. To learn about the kinetic details of the formation of this unusual structure, the temperature-dependent structural evolution of graphitic carbon from MF in the presence of nano-CaCO3 was investigated. The nano-CaCO3, here, has a triple role:it acts as a hard template to generate the characterized structuring, as an inner activating agent to in situ active the carbon materials producing micropores and mesopores, and as a novel versatile catalyst for graphitization. Attractively, this simple route is also capable of producing hierarchical porous graphitic carbons with high surface area (1683 m2/g) and extremely large pore volume (6.7 cm3/g) by using carbohydrate or phenolic resin as carbon precursor. The results indicate that the intermediates CaCN2 and Ca(CN)2 (CaO and CaC2 for non-N-containing carbons) generated during the carbonization plays a critical role in the formation of highly graphitized structure.We believe these novel synthetic approachs will not only pave new ways for the preparation of N-enriched porous materials but also for mass production of high-quality nanostructured porous materials, since much more materials can be directly obtained by the current methods. |
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