The Self-assembly Synthesis and CO₂ Adsorption Property of Boron-doped Mesoporous C/SiO₂ Composites

A serias of novel mesoporous carbon/silica composites (BC/SiO₂) with abundant mesoporous structure were successfully prepared with the sol-gel self-assembly method, wherein triblock copolymer F127 was used as a template, tetraethoxysilane was used as an inorganic silicon precursor, and phenolic resin and triisopropyl borate were selected as C- and B- containing precursors. Meanwhile, the effect of the content of boron doped on the CO₂ capture capacity of BC/SiO₂ composites was investigated and the adsorption isotherms of CO₂ were determined. The results were fitted and analyzed using three kinds of adsorption isotherms models (Langmuir, Freundlich and DSL models). These results demonstrated that the BC/SiO₂ composites exhibited a spherical shape and had a high specific surface area and uniform pore distribution and a large amount of boron atoms was uniformly doped in the carbon framework of BC/SiO₂ composite, which introduced the polar sites. The capability of capturing CO₂ was not only related to the specific surface area of the composite material but also to the number of polar sites generated by doped boron. It was found that the adsorption CO₂ molecules on BC/SiO₂ composites presented two adsorption sites with different degrees and adsorption isotherms of CO₂ were highly consistent with the DSL model.