Resorcinol-formaldehyde gel

In templating method, many polymeric precursors including resorcinol-formaldehyde gel,38,40,42,69,70,73"76 furfuryl alcohol,41,49,53, 55 7677 phenolic resin,49 72 74 melamine-formaldehyde resin,69,72 and mesophase pitch,17,45,46,54 etc. are generally used as carbonaceous precursors. The porous carbons are prepared by templating method according to the following procedures ... 

Carbon materials issued from evaporative drying and pyrolysis of resorcinol-formaldehyde gels were used as metal catalyst supports. These carbons, whose pore texture and composition are controllable, lead to high metal dispersion. Moreover, pore texture control is a great advantage diffusional limitations can be lowered, and even eliminated, by choosing an appropriate pore texture range. 

In templating method, many polymeric precnrsors inclnding resorcinol-formaldehyde gel,38 40.42,69,70,73-76 alcohol, " ... 

Other carbon sources have also been used as matrices such as multiwall carbon nanotubes (MWNTs), which led to narrower mesopore distributions than with carbon black pearls. In addition, the use of carbon fibers also allowed cylindrical mesopores to be obtained with low tortuosity. Carbon aerogel monoliths, obtained from resorcinol-formaldehyde gels after drying with COj under supercritical conditions and pyrolysis under nitrogen atmosphere at 1323 K, have also been used as templates for the generation of mesoporosity in zeolites [158]. This method presents the added advantage that the mesoporous zeolite can be synthesized as a monolith. 

Even when looking at samples with rather good contrast, such as mineral oxides in water, much longer exposure times (of the order of minutes) must be used with X-ray scattering than with light (of the order of seconds) and samples must, in general, be much more concentrated. Berthon et al. [45] used USAXS to measure fractal structure in resorcinol-formaldehyde gels. 

Mathieu, A., Blacher, S., Pirard, R., Pirard, J.P., Sahouli, B. and Brouers, F. (1997). Freeze-dried resorcinol-formaldehyde gels. J. Non-Cryst. Solids, 212, 250-261. 

B. Mathieu, S. Blacher, R. Pirard, J.-P. Pirard, B. Sahouh, and F. Brouers, Freeze-Dried Resorcinol-Formaldehyde Gels, J. Non-Cryst. Solids, 212, pp. 250-61, 1997. 

Kocklenberg R, MathieuB,BlacherS, PirardR, Pirard JP, Sobry R, VandenBossche G (1998) Texture control of freeze-dried resorcinol-formaldehyde gels. J Non-Cryst Solids 225 8-13... 

Gommes C J, Roberts A P (2008) Structure development of resorcinol-formaldehyde gels Microphase separation or colloid aggregation. Physical Review E 77 041409-041421... 

Gommes C J, Job N, Prrard J Pet al (2008) Critical opalescence points to thermodynamic instability relevance to smaU-angle X-ray scattering of resorcinol-formaldehyde gel formation at low pH. Journal of Applied... 

Gross J, Scherer G W, Alviso C T et al (1997) Elastic properties of crosslinked Resorcinol-Formaldehyde gels and aerogels. Journal of Non-Crystalline Solids 211 132-142... 

Despetis F, Barral K, Kocon L, Phalippou J (2000) Effect of aging on mechanical properties of resorcinol-formaldehyde gels. J Sol-Gel Sci Tech 19 829-831. 

Hyeon et al. [116] successfully synthesized carbon nanoeoils composed of nanometer-thiek graphitic fibers by the catalytic graphitization of a resorcinol-formaldehyde gel. The carbon nanocoils were applied as eleetrode materials for direct methanol fuel cells. The SEM image reveals that the carbon materials consisted of partieles approximately 100 mn in diameter (Figure 10.14(a)). The TEM image (Figure 10.14(b)) shows that each individual particle is composed of... 

Job N, PanarieUo F, Marien J, Crine M, Pirard JP, Leonard A (2006) Synthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels. J Non-Cryst Solids 352 24-34... 

The carbon support used in this smdy is a mesoporous xerogel X25 (maximum mesopore size ca. 25 run, Sbet 660 m. g ), obtained by evaporative drying and subsequent pyrolysis of an aqueous resorcinol-formaldehyde gel prepared imder well-... 

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