The pore structure evolution and stability of mesoporous carbon FDU-15 under CO₂, O₂ or water vapor atmospheres

Mesoporous carbons FDU-15 with ordered hexagonal structure were prepared by using triblock copolymer Pluronic F127 as a template and resol as a carbon precursor via evaporation induced organic-organic assembly method. The pore structure evolution and stability of FDU-15 functioned with the treatment temperature and time were systematically investigated in CO₂, O₂ or water vapor atmospheres. A variety of techniques such as powder X-ray diffraction (XRD), nitrogen sorption and transmission electron microscopy (TEM) were used to characterize the thermal stability of the carbon mesostructure. N₂ sorption measurements show that the activation process can simply increase the specific surface area and pore volume of the mesoporous carbons. The effect of structural regularity, pore size, meso- or microporosity, and wall thickness on the thermal stability at different treatment temperature and time was discussed. The results show that mesoporous carbon FDU-15 materials after the carbonization at 900 °C have a good thermal stability under CO₂ at 750 °C, O₂ at 350 °C and water vapor at 800 °C for at least 3 h. Nevertheless, CO₂, O₂ or water vapor develops the pore system through different ways. For CO₂, the thermal treatment leads to large mesopore volumes while the micropores are slightly increased during the carbon burn-off. Different from CO₂, water vapor activation renders a continuous increase of micropore volumes as well as the total pore volumes with increasing the carbon burn-off. Under O₂-treatment at 350 °C, the ordered mesostructures can be rapidly destroyed due to the fast burning reactions of oxygen with mesoporous carbons.