Preparation Of Hierarchical Ordered Mesoporous Carbon Materials Deriving From Starch

Mesoporous carbon materials are a novel porous materials with high surface area, high pore volume, uniform pore structure, superior physical and chemical properties, and are widely applied in adsorption of large molecules, heterogeneous catalyst supports, water purification filters, electric double layer capacitors, energy generation and storage applications. Templating technology is the most effective method to synthersis ordered mesoporous carbon. However, the pore structure is difficult to adjust and the surface chemical properties are not easy to modify due to its hydrophobic. Pore structure and surface chemical properties of carbon materials determine their applications. Compared with the ordered mesoporous carbon that derived from templating process, hierarchical mesoporous carbons with plenty of surface chemical groups should display potential application advantage.In this work, hierarchical ordered mesoporous carbons were synthesized by using starch as precursor at lower carbonization temperature. Based on the structural property of starch molecules and adopting molecular self-assembly technology, starch was formed an organized nanoscale lamellar structure through self-assembly. Hierarchical mesoporous carbon was obtained after carbonization, its yields and benzene adsorption amounts were investigated. The detail preparation process, such as, solvent, gelatinization temperatures and time, additive reagents, block polymerization, drying condition and carbonization temperature were compared and analyzed. The pore structures and surface chemical properties of the carbon samples were characterized by N2 adsorption-desorption isothermal, scanning electron microscopy and FT-IR spectra.The results showed that Hierarchical mesoporous carbon materials could be synthesized by using starch as precursor without template agent at lower carbonization temperature. The higher benzene adsorption amount of hierarchical mesoporous carbon was synthesized as following: hydroxypropyl starch mixed with distilled water in mass ratio of 1:1, gelatinized at 85oC for 6h, then extracted by solvent and dried at 75oC for 12h, finally, carbonized at 600oC~800oC for 2h with a nitrogen flow of 30ml/min. The surface area and pore volume of prepared hierarchical mesoporous carbons were 250m2/g~1200m2/g and 0.250cm3/g~0.600cm3/g, respectively, the pore size distribution was around 3.8nm and 10.0nm~40.0nm and the mesoporous content was higher than 70%. The surface chemical groups of hierarchical mesoporous carbon were mainly hydroxyl and carbonyl, so, it was easy to modify and introduce some new groups.