Porosity carbons

Coating of fine-porosity carbon for catalytic applications. 1... 

High porosity carbons ranging from typically microporous solids of narrow pore size distribution to materials with over 30% of mesopore contribution were produced by the treatment of various polymeric-type (coal) and carbonaceous (mesophase, semi-cokes, commercial active carbon) precursors with an excess of KOH. The effects related to parent material nature, KOH/precursor ratio and reaction temperature and time on the porosity characteristics and surface chemistry is described. The results are discussed in terms of suitability of produced carbons as an electrode material in electric double-layer capacitors. 

Weng T.C., Teng H., Characterization of high porosity carbon electrodes derived from mesophase pitch for electric double-layer capacitors, J. Electrochem. Soc. 2001 148 368-373. 

M. Mirzaeian and P.J. Hall, Preparation of controlled porosity carbon aerogels for energy storage in rechargeable lithium oxygen batteries, Electrochim. Acta, 54(28) 7444-7451, December 2009. 

Lozano-Castello D., Lillo-Rodenas M.A., Cazorla-Amoros D., Linares-Solano A., Preparation of activated carbons from Spanish anthracite. Carbon 2001 39 741-749. Weng T.C., Teng FI., Characterization of high porosity carbon electrodes derived from mesophase pitch for electric double-layer capacitors, J. Electrochem. Soc. 2001 148 368-373. 

Porosity. The fraction of total (bulk) volume occupied by the voids is defined as the porosity of the porous medium. A porous medium can be classified according to the type of porosity involved. In sandstone and unconsolidated sand, the voids are between sand grains, and this type of porosity is known as intergranular. Carbonate rocks are more complex and may contain more than one type of porosity. The small voids between the crystals of calcite or dolomite constitute intercrystalline porosity (47). Often carbonate rocks are naturally fractured. The void volume formed by fractures constitutes the fracture porosity. Carbonate rocks sometimes contain vugs, and these carbonate rocks constitute the vugular porosity. Still some carbonate formations may contain very large channels and cavities, which constitute the cavernous porosity. 

The coking and regeneration of a reforming catalyst was studied by physical characterization methods (pore volume, tortuosity, porosity, carbon distribution) as well as by kinetic investigations on the reaction rate of coke bum-off. For temperatures of industrial relevance for the Pt/Re-A Os catalyst, i.e. below 550°C (deactivation), the bum-off rate is determined by the interplay of chemical reaction and pore diffusion limitation by external mass transfer can be excluded. Based on the kinetic parameters, the process of the regeneration of a technical reactor is discussed. 

Keywords Freeze-drying synthesis Co-precipitation Nanoparticle isolation Oriented porosity Carbon cryogel... 

Carbon is a commonly used solid electrode material as a substrate for biosensors, particularly in the form of glassy carbon, due to its wide positive potential window, mechanical stability, and low porosity. Carbon film, carbon composite and graphite are other substrates which have been investigated. Carbon film electrodes made from carbon film electrical resistors have been extensively employed by us as electrode substrate [43], obtained by pyrolytically coating a ceramic cylindrical substrate with a thin carbon layer. 

Gahan et al. (2004) High-porosity carbons were prepared from bituminous coal pitches by combining chemical and physical activation. Chemical activation used KOH impregnation (450 °C for 1 h) followed by carbonization in nitrogen (375-850 °C). The ratio of KOH pitch of 3 1 optimized the development of porosity. In the carbonization range 800-850 °C, a carbon was produced with a micropore volume of 1.02cm g" and a BET surface area of 2350 m g . 

Thionyl chloride, sulphuryl chloride or sulphur dioxide where the solvent is also the electroactive species at the positive electrode, made from a high surface-area, high-porosity carbon. In thionyl and sulphuryl chloride cells the electrolyte is usually lithium tetrachloroaluminate while sulphur dioxide is... 

Kohhneyer, R. R., Ror, M., Deng, J., Riu, H., and Chen, J. 2011. Preparation of stable carbon nanotube aerogels with high electrical conductivity and porosity. Carbon 49 2352-2361. 

The irradiation behavior of the C/C materials is more complex and there are much less results in the literature than for the graphite materials. They are nonhomogeneous materials and possess various constituents (fibers, matrix, interface, multiscale porosity), carbon textures, and geometrical structures that influence the irradiation behavior. One of the most essential requirements, and the hardest to fulfill, for a high level of irradiation, such as for control rod applications, is dimensional stability (a variation of 2%, at the working temperature is generally considered as a maximal acceptable value). 

Figure 12. Effect of pore size and distribution on the electrical behavior of various types of carbon. Dependence of phase angle on frequency for (o) 76-angstrom controlled porosity carbon ( ) 166-angstrom controlled porosity carbon (x ) C black (Black-Pearls) (+) high surface-area activated carbon. (Adapted with permission from Ref. 46.)...

P. Eklund, T. C. M. Chung, H. C. Foley, and V. H. Crispy, Advanced Boron and Metal-Loaded High Porosity Carbons, DOE Hydrogen Program Annual Progress Report, Department of... 

Focke and Munn (1987) found that low porosity carbonates with mostly interparticle (intercrystalline) porosity are associated with m values below 2. A higher percentage of moldic or vuggy porosity raises m values from 1.8 at low porosities to over 5 at high porosities. 

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