Abstract:
Al
2O
3-C hybrid aerogels were prepared by a one-pot sol-gel method,supercritical n-hexane drying and carbonization using Al (NO
3)
3·9H
2O as the Al
2O
3 source,resorcinol (R) and furfural (F) as carbon precursors,and propylene oxide (PO) as a gelation initiator.The effects of the Al
2O
3 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 Al
2O
3 is
γ-type,but its diffraction peaks are quite broad.The hybrid aerogels are monolithic when the Al
2O
3 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 Al
2O
3 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.