中孔炭的水玻璃模板法制备、结构调控及球形功能化

以廉价水玻璃为原料, 通过控制水解条件, 合成出具有不同尺寸的SiO₂溶胶, 并与间苯二酚-甲醛(RF)溶胶形成均相的凝胶复合物, 经常压干燥、炭化、酸洗, 得到具有可控结构的中孔炭材料。考察了水解温度、水解时间和反应物组成对孔结构的影响, 并通过氮气吸附、扫描电镜和透射电镜对材料的微观结构进行了表征。结果表明: 中孔炭的孔隙反相复制于SiO₂凝胶网络, 其平均孔径随水解时间的延长或水解温度的升高而增大, 并在6~12 nm范围内精细调控, 而其总孔隙率可以通过改变炭、SiO₂前驱体比例调节。对液相复合溶胶通过悬浮聚合法和喷雾干燥法处理, 分别制备出毫米级和微米级的中孔炭球, 进而实现了中孔炭在宏观形貌上的调控。本工作为中孔炭的低成本制备、精细结构调控以及球形功能化提供了重要参考。

Facile Preparation,Structural Control and Spheroidization of Mesoporous Carbons Using Hydrolyzed Water Glass as a Template

Mesoporous carbons (MC) with controlled pore structure were synthesized using hydrolyzed water glass (sodium silicate) as hard template precursor. The mixture of carbon precursor (resorcinol-formaldehyde) sol and silica sol followed by Sol-Gel process generated a polymer/silica dual hydrogels. After ambient drying, carbonization and HF etching, mesoporous carbons with developed mesoporous structure were obtained. The hydrolysis conditions of water glass including hydrolysis temperature and hydrolysis time, and the weight ratio of RF polymer to silica were studied respectively to investigate their effects on the mesoporous structure. The microstructures of the mesoporous carbons were characterized by N₂ adsorption, SEM and TEM observations. It was found that as-prepared mesoporous carbons displayed disordered mesoporous channels which replicated from the initial colloidal silica networks. The average mesopore size could be precisely adjusted in the range from 6 nm to 12 nm by tuning the hydrolysis time and hydrolysis temperature, while the total porosity could be controlled by changing the weight ratio of polymer precursor to silica. Furthermore, with the assistant of suspension polymerization and spray drying technologies, spherical mesoporous carbons with millimetre and micrometer-sized particles were produced, respectively. The present work provides a low-cost approach for deliberately controlling the mesoporous structure and spherical morphology to mesoporous carbons that can be extended to many different applications.