Silica aerogel pore size distributions

Fig. 7. The effect of preparation on the pore size distribution (a), titanium dispersion (b), and the activity for epoxidation of cyclohexene (c) of titania—silica containing 10 wt % titania and calcined in air at 673 K. Sample A, low-temperature aerogel Sample B, high-temperature aerogel Sample C, aerogel.

These results, coupled with the recent findings in solgel, aerogel, and modified aerogel syntheses of porous metal oxides, as well as the literature of zeolites, pillared clays, and mesoporous silicas, suggest that future investigations will lead to precise control of pore sizes, pore size distribution, and chemical functionality of the pore walls. 

El Rassy H, Buisson P, BouaU B, Perraid A, Pierre AC (2(X)3) Surface Characterization of Silica aerogels with Different Proportions of Hydrophobic Groups, dried by the CO2 Supercritical Method Langmuir, 19 358-363 Harreld JH, Ebina T, Tsubo N, Stucky G (2(X)2) Manipulation of pore size distributions in silica and ormosil gels dried under ambient pressure crmditions. J Non-Cryst Solids 298 241 251... 

Zeng, S.Q., A.J. Hunt, W. Cao, and R. Greif. 1994. Pore size distribution and apparent gas thermal conductivity of silica aerogel. Journal of Heat Transfer 116(3) 756-759. 

Here, C is a constant for material stiffness that needs to be determined experimentally. Figure 5.10b shows the pore size distribution obtained using this equation. It should be noted that densification curves may also be used to determine the bulk compression modulus of silica aerogels (Scherer et ah, 1995b). 

Brown S.M., Lard E.W. A comparison of nitrogen and mercury pore size distribution of silica of varyingpore volume. Powder Technol. 1974 9 187 Dieudonne, Ph., Phalippou J. Textural properties ofdensified aerogels. J. Sol-Gel Sci. Technol. 1999 14 1... 

Figure 13-8. Pore size distribution of silica aerogels, determined by nitrogen-adsorption isotherms.

Pore size distribution for silica aerogel after treatments with water, (a) Original sample, (b) After storage in water vapor, (c) After storage in liquid water. These data obtained by nitrogen adsorption do not reveal the larger pores that constitute most of the pore volume. From Schuck et at. [102]. 

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