用Al(NO3)3·9H2O 作为Al2O3 源,间苯二酚-糠醛为碳源,环氧丙烷为凝胶促进剂,通过溶胶-凝胶方法一釜合成了湿凝胶,并经超临界正己烷干燥和碳化制备了Al2O3-C 杂化气凝胶. 研究了Al2O3含量、间苯二酚-糠醛浓度和环氧丙烷/铝摩尔比对所合成的杂化气凝胶孔隙性质的影响.结果表明,此杂化气凝胶均为中孔结构,其平均孔径小于20 nm,Al2O3属于γ-型结构但X射线衍射峰很宽.杂化气凝胶在Al2O3含量小于5.31 wt%和间苯二酚-糠醛浓度为10 g/mL时可形成整体块状.在其他条件相同的情况下,中孔孔容、BET比表面、外表面积和中孔孔径随环氧丙烷/铝摩尔比增加而增大.制备过程中凝胶的体积收缩率和炭化收率随Al2O3含量增加而增大,但密度随Al2O3含量增加在4.93 wt%处达到最大.中孔孔容和孔径以及外表面积在环氧丙烷/铝摩尔比为5和6时随间苯二酚-糠醛浓度增加而减小,而在环氧丙烷/铝摩尔比为4时随间苯二酚-糠醛浓度增加而增大.
Al2O3-C hybrid aerogels were prepared by a one-pot sol-gel method, supercritical n-hexane drying and carbonization using Al(NO3)3·9H2O as the Al2O3 source, resorcinol (R) and furfural (F) as carbon precursors, and propylene oxide (PO) as a gelation initiator.The effects of the Al2O3 contents, the R+F concentrations and the PO/Al molar ratios on the porosity of the hybrid aerogels were investigated using a constant R/F molar ratio of 0.5.It was found that the hybrid aerogels are all mesoporous with an average pore size below 20 nm.The crystalline structure of Al2O3 is γ-type, but its diffraction peaks are quite broad.The hybrid aerogels are monolithic when the Al2O3 content is below 5.31 wt% with an R+F concentration of 10 g/100 mL.The mesopore volume and size, BET surface area and external surface area all increase with increasing PO/Al molar ratio under otherwise identical conditions.The volume shrinkage decreases, carbonization yield increases and the density of the hybrid aerogel exhibits a maximum with an Al2O3 content of 4.93 wt%.The size and volume of the mesopores, and the external surface area decrease with the increasing R+F concentration at PO/Al ratios of 5 and 6, but increase with increasing R+F concentration at a PO/Al ratio of 4.
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