Synthesis of Carbon Aerogels

Wiener, M., Reichenauer, G., Scherb, T, Fricke, J., 2004. Accelerating the synthesis of carbon aerogel precursors. /. Non-Cryst. Solids 350 126-130. 

Berthon-Fabry et al. detected significant anisotropies in the SAXS pattern of carbon aerogels derived with acetone as a solvent and harsh synthesis conditions the anisotropy was found for q values <4 x 10 nm , while the scattering pattern revealed an isotropic structure at larger scattering vectors [41]. 

Abstract Carbon aerogels are nanostructure porous carbon materials with high specific surface areas and relative low electric resistance. In recent years, they have attracted much attention because of their extraordinary properties and potential uses in a wide variety of technological applications. Many studies have been carried out concerning carbon aerogel synthesis and characterization. This contribution summarizes recent developments in the synthesis, properties, and applications of carbon aerogels. 

Whereas no reaction occurred in the absence of catalyst, ruthenium catalysts were able to remove most of the Total Organic Carbon (TOC) of p-HBZ acid aqueous solutions at relatively mild conditions after 7h. The most important intermediates detected were phenol, hydroquinone and maleic acid. The results related to the study of the effects of the acid used for the preparation of aerogel supports (TiOa, ZrOa) and the nature of ruthenium precursor on the catalytic properties of the samples are gathered in the Tables 4 and 5. As shown in Table 4, the use of nitric acid during the synthesis of the Ti02 support and Ru(N0)(N03)3 as the metal precursor leads to the more efficient Ru/TiOa catalyst (63.8% TOC abatment). 

Synthesis of Zr-doped carbon aerogels resnlted in microporons materials, whereas doping with Ce only yielded a material with very low microporosity. 

To date, metal-doped carbon aerogels and xerogels have been used as catalysts in different reaction types, which can be grouped into environmental and fuel cell applications, C=C double-bond hydrogenation, skeletal isomerization, hydrodechlorination, and other reactions, including synthesis of methyl... 

X. K. Li, L. Liu, Y. X. Zhang, Sh. D. Shen, Sh. Ge and L. Ch. Ling, Synthesis of nanometre silicon carbide whiskers from binary carbonaceous silica aerogels. Carbon, 39,159-165(2001). 

Fig. 5.8 Synthesis of metal-doped organic and carbon aerogels (post-synthesis, impregnation).

Aerogels are quasi-stable, low-density, three-dimensional assemblies of nanoparticles, which have usually poor mechanical properties. A facile one-pot synthesis of Kevlar-like aerogels based on the reaction of multifunctional isocyanates and carboxylic acids has been reported [57]. The materials exhibit an ultimate compressive strength, a high specific energy absorption, and a thermal conductivity like foamed PS. By a pyrolysis process at 800 °C, the materials can be converted to a porous, electrically conducting carbon with a high surface area. 

Chidambareswarapattar C, Larimore Z, Sotiriou-Leventis C, Mang JT, Leventis N (2010) One-step room-temperature synthesis of fibrous polyimide aerogels from anhydrides and isocyanates and conversion to isomorphic carbons. J Mater Chem 20 6978-9666... 

Han TY-J, Worsley MA, Baumann TF, Satcher JH (2011) Synthesis of ZnO coated activated carbon aerogel by simple sol-gel route. J Mater Chem 21 330-333... 

In the field of carbon nanotubes synthesis, widely studied for the moment, the one-step sol-gel method is examined as a way to prepare bimetallic catalysts leading to a high productivity in single-walled carbon nanotubes (SWNTs). For example, Su et al. [145] prepared a Fe-Mo/AljOj aerogel (dried in supercritical COj) and Mehn et al. [133] prepared a Fe-Mo/AljOj cryogel (freeze-dried) both with a good activity in SWNTs synthesis. 

C. Moreno-CastUla, F. J. Maldonado-H6dar, J. Rivera-UtriUa, and E. Rodriguez-Castellon, Group 6 Metal Oxide-Carbon Aerogels. Their Synthesis, Characterization and Catalytic Activity in the Skeletal Isomerization of 1-Butene, Appl. Catal. A, 183, pp. 345-56, 1999. 

F. J. Maldonado-Hodar, M. A. Ferro-Garcfa, J. Rivera-UtrUla, and C. Moreno-CastiUa, Synthesis and Textural Characteristics of Organic Aerogels, Transition-Metal-Containing Organic Aerogels and their Carbonized Derivatives, Carbon, 37, pp. 1199-1205, 1999. 

Worsley, M.A., Satcher, J.H., and Baumann, T.E (2008) Synthesis and characterization of monolithic carbon aerogel nanocomposites containing double-walled carbon nanotubes. Langmuir, 24(17), 9763-9766. 

Wohlgemuth SA, White RJ, Willinger MG, Titirici MM, Antonietti M (2012) A one-pot hydrothermal synthesis of sulfur and nitrogen doped carbon aerogels with enhanced electrocatalytic activity for oxygen reduction reaction. Green Chem 14 1515-1523... 

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