B掺杂介孔C/SiO2复合材料的自组装法合成及其CO2吸附性能

采用溶胶-凝胶结合协同自组装法，以三嵌段共聚物F127为模板剂，以正硅酸乙酯为硅源，以酚醛树脂为碳源，改变硼酸三异丙酯硼源的投料量，制备了一系列具有丰富介孔结构的新型B掺杂介孔C/SiO₂复合材料(BC/SiO₂)，研究B的掺杂量对BC/SiO₂复合材料CO₂吸附性能的影响，采用3种等温吸附模型(Langmuir、Freundlich和DSL)分别对CO₂等温吸附曲线进行拟合分析。结果表明:BC/SiO₂复合材料呈球形，且具有较高的比表面积和均一的孔径分布；在BC/SiO₂复合材料中，大部分B原子已被均匀掺入到碳骨架中，从而产生极性位点；BC/SiO₂复合材料对CO₂的吸附能力不仅与材料比表面积大小有关，同时也与B掺杂所产生极性位点数量相关；B掺杂的BC/SiO₂复合材料对CO₂分子存在2种不同强弱的吸附位点，CO₂吸附等温线符合DSL等温吸附模型。

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.