)Preparation of ordered macroporous carbons by using ice crystal growth and control of their hierarchical structure

以间苯二酚和甲醛为原料，通过溶胶-凝胶缩聚、单向冷冻、冷冻干燥、热解等工艺制备了碳冷冻微蜂窝。CMHS具有大孔和中孔/微孔的分级结构。然而，CMHS的孔隙率低于传统方法制备的碳冷冻胶。研究了冷冻、HCl老化或CO2活化对CMHS多孔性能的影响。冷冻操作大大减少了CMHS的中孔体积。由于冷冻操作是制备CMHS不可缺少的步骤，因此其孔隙率应在形成蜂窝结构后形成。有机微孔蜂窝的HCl老化可形成CMHS的微孔或中孔。CO2活化对提高CMHS的孔隙率非常有利，因为活化过程中保留了蜂窝结构。将间苯二酚-甲醛水凝胶的合成条件与CO_2活化条件相结合，可以制备出介孔发达的CMH。将炭黑在硅溶胶中减压浸泡，通过单向冷冻、溶剂交换、冷冻干燥等方法制备了碳-二氧化硅复合材料。通过单向冷冻，可以在CMHS内部形成硅胶蜂窝或纤维状硅胶。实验结果表明，以胶体白炭黑为原料制备硅胶，可制得结晶度高、抗压强度高的碳-白炭黑复合材料。

Carbon cryogel microhoneycombs (CMHs) were prepared via sol-gel polycondensation of resorcinol with formaldehyde, unidirectional freezing, freeze drying and pyrolysis. CMHs had a hierarchical structure of macropores and meso/micropores. However, the porosity of CMHs was lower than that of carbon cryogels prepared by a conventional method. The influence of freezing, HCl aging or CO_2 activation on their porous properties of CMHs was studied. The freezing operation greatly decreased the mesopore volume of CMHs. Since the freezing operation was indispensable to the preparation of CMHs, their porosity should be developed after the formation of honeycomb structure. The HCl aging of organic microhoneycombs could develop micropores or mesopores of CMHs. CO_2 activation was extremely useful for improving porosity of CMHs because the honeycomb structure was kept during activation. The CMH whose mesoporosity was much developed could be prepared by the combination of synthesis conditions of resorcinol-formaldehyde hydrogels and CO_2 activation. The CMHs were also immersed in silica sol under reduced pressure, and the carbon-silica composites were prepared via unidirectional freezing, solvent exchange and freeze drying. Silica gel honeycombs or fibrous silica gels could be formed inside the CMHs by unidirectional freezing. The experimental results suggested that the carbon-silica composites with high crystalinity and high compressive strength were prepared in the case where colloidal silica was used as a raw material for silica gels.