Fairén-Jiménez David, Carrasco-Marín Francisco, Djurado David, Bley Françoise, Ehrburger-Dolle Françoise, Moreno-Castilla Carlos
Departamento de Química Inorganica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
J Phys Chem B. 2006 May 4;110(17):8681-8. doi: 10.1021/jp055992f.
A carbon aerogel was obtained by carbonization of an organic aerogel prepared by sol-gel polymerization of resorcinol and formaldehyde in water. The carbon aerogel was then CO(2) activated at 800 degrees C to increase its surface area and widen its microporosity. Evolution of these parameters was followed by gas adsorption and small- and wide-angle X-ray scattering (SAXS and WAXS, respectively) with contrast variation by using dry and wet (immersion in benzene and m-xylene) samples. For the original carbon aerogel, the surface area, S(SAXS), obtained by SAXS, is larger than that obtained by gas adsorption (S(ads)). The values become nearly the same as the degree of activation of the carbon aerogel increases. This feature is due to the widening of the narrow microporosity in the carbon aerogel as the degree of activation is increased. In addition, WAXS results show that the short-range spatial correlations into the assemblies of hydrocarbon molecules confined inside the micropores are different from those existing in the liquid phase.
通过间苯二酚和甲醛在水中进行溶胶 - 凝胶聚合制备有机气凝胶，再经碳化得到碳气凝胶。然后将碳气凝胶在800℃下进行CO₂活化，以增加其表面积并拓宽其微孔率。利用干样品和湿样品（浸入苯和间二甲苯中）通过气体吸附以及小角和广角X射线散射（分别为SAXS和WAXS）并采用对比变化法跟踪这些参数的演变。对于原始碳气凝胶，通过SAXS获得的表面积S(SAXS)大于通过气体吸附获得的表面积（S(ads)）。随着碳气凝胶活化程度的增加，这些值变得几乎相同。此特征归因于随着活化程度的增加，碳气凝胶中狭窄微孔的拓宽。此外，WAXS结果表明，限制在微孔内的烃分子聚集体中的短程空间相关性与液相中存在的不同。
