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This work reports some surface and structural features of multi-wall carbon nanotubes (MWNT)-supported PtPd crystallites in order to explain their very good ability to hydrogenate aromatic rings in comparison with other catalyst systems consisting of the same metallic function but changing the support substrate (amorphous SiO 2 –Al 2 O 3 (ASA) and silica-delaminated zirconium...
A three-dimensional microstructure of green and pressed tapes cast with graphite particles of non-spherical shape were examined quantitatively on the basis of the distribution of void sizes among the packed particles. The distributions measured over the cross-sections of the tape in three directions were expressed by the theoretical ones deduced for non-spherical particles. Particle shape was characterized...
Carbon aerogels were successfully fabricated by a microemulsion-templated sol–gel polymerization method. When a suitable molar ratio of surfactant to resorcinol (S/R) and an appropriate resorcinol–formaldehyde concentration were selected, the organic gels thus obtained could be dried with little shrinkage by heating at ambient pressure. The size of carbon nano-particles and the pore size of carbon...
Adsorption dynamics are of fundamental importance in applications of adsorbents in real situations. The adsorption/desorption characteristics of a series of adsorbates, with varying hydrophilic/hydrophobic and structural characteristics, for activated carbon BAX950, were investigated for temperatures in the range 288–323K. These data provide a comprehensive kinetic study of adsorption/desorption for...
Previous studies of the adsorption of benzene and toluene at low concentration showed that both porosity and surface chemistry of the activated carbon play an important role. This paper analyses the adsorption behaviour of a mixture of VOCs (benzene–toluene) on AC, due to the lack of information regarding the adsorption of mixtures. Thus, the performance of chemically activated carbons, physically...
A series of carbon foams was developed by using low-cost precursors, such as coal, coal tar pitch and petroleum pitch. The properties of the resultant carbon foams cover a wide range, e.g., bulk density, 0.32–0.67g/cm 3 , compressive strength, 2.5–18.7MPa, isotropic and anisotropic microstructure, etc. The investigation of foaming mechanism and the relationship between properties and structure...
Physical and chemical properties of activated carbons produced from commercial xylan, cellulose, and Kraft lignin by H 3 PO 4 activation at various process conditions were studied. The results show that the more reactive the precursor under acidic conditions, the easier the porosity development, particularly mesoporosity. In addition, Boehm titration and Fourier Transform Infrared...
The experimental conditions for the pyrolysis of olive stones to produce a swelling of the particle and eventually the formation of carbon foam are described and discussed. The greatest expansion of the material occurred when 200–300g of precursor, in the presence of steam at a pressure of 1MPa, is introduced into a 1000ml stainless steel reactor placed inside a sand-bath furnace previously heated...
Fatigue behaviour of polycrystalline, isotropic graphite FU2590 (porosity 13vol%) and of FU2590 infiltrated with the aluminium alloy AlSi7Mg (FU2590/AlSi7Mg) is investigated. The interpenetrating graphite–aluminium composite is produced by squeeze casting infiltration, where the open porosity of FU2590 (10–11vol%) is infiltrated with AlSi7Mg. Fully reversed bending fatigue tests at cycling frequency...
The preferential blocking of the interior adsorption sites of single walled carbon nanotubes (SWNTs) by n-nonane is demonstrated. Following adsorption of n-nonane and evacuation for 24h at 323K, it was found that interior sites with diameters less than ∼14Å remained filled with n-nonane, blocking the physical adsorption of N 2 on these sites at 77.3K. We demonstrate that “nonane blocking”...
Carbon aerogels were prepared by polymerization of a resorcinol–formaldehyde mixture using different polymerization catalysts such as: sodium or potassium carbonates, oxalic acid or para-toluenesulfonic acid. The carbon aerogel obtained with this last acid was further CO 2 -activated to 8.5% and 22% burn-off. All samples were characterized by N 2 and CO 2 adsorption at −196...
A soft chemical method was used to insert silica bridging species between the layers of a graphite oxide precursor to form nanoporous graphitic composites (NPGC) and the effect of various synthetic conditions including colloidal dispersion, interlayer pre-expansion, and hydrolysis of silica source on the pore formation of NPGC was examined. It was found that an optimal alkali concentration for GO...
A series of activated carbons (ACs) with progressively changing nanotextural characteristics was obtained by heat-treatment of a bituminous coal at temperatures ranging from 520 to 1000°C, and subsequent activation by KOH at 700°C or 800°C. As the pre-treatment temperature increases, the total pore volume V T decreases from 1.28 to 0.30cm 3 g −1 , and the BET specific surface...
Different fibrous activated carbons were prepared from natural precursors (jute and coconut fibers) by physical and chemical activation. Physical activation consisted of the thermal treatment of raw fibers at 950°C in an inert atmosphere followed by an activation step with CO 2 at the same temperature. In chemical activation, the raw fibers were impregnated in a solution of phosphoric acid...
We have developed a method that would allow for the fabrication of carbon aerogel (CA) spheres. The inverse phase suspension polymerization of resorcinol and formaldehyde monomers with Na 2 CO 3 as a catalyst followed by supercritical drying was explored. The effects of the chemical formulation and processing procedures and the conditions of the structures of organic and related carbon...
Scanning tunneling microscopy (STM) has been employed for a comparative structural characterization, down to the atomic scale, of a representative set of porous carbons with different adsorption characteristics and prepared either by activation (physical or chemical) or templating techniques. The studied materials included a chemically activated, supermicroporous high surface area carbon, two activated...
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