Carbon, activated characterization

Rodrigucz-Rcinoso, F., Activated carbon structure, characterization,... 

The adsorption of hydrocarbons by activated carbon is characterized by the development of adsorption isotherms, adsorption mass and energy balances, and dynamic adsorption zone flow through a fixed bed. 

Specific Activity (SA) and Mass Activity (MA) of Pt Electrocatalysts Supported on Different Carbon Powders Characterized by Specific Surface Area (S) and Particle Size (d)... 

Rodrigucz-Reinoso, F., Activated carbon structure, characterization, preparation and applications. In Introduction to Carbon Technologies, ed. H. Marsh, E. A. Heintz and F. Rodriguez-Reinoso, University of Alicante (Spain) Publications, 1997, pp. 35 101. 

The yields obtained after 10 min in a batch reactor with MgO, CaO, or SrO exceeded 92%, whereas with BaO the yield was lower (72%), probably because of its low surface area (2m /g). When alkaline earth hydroxides were used as basic catalysts, the yields were lower than for the corresponding oxides. The most active hydroxides were Sr(OH)2 8H2O and Ba(OH)2 8H2O, which gave the additional compound in yields of 75% and 70%, respectively, whereas carbonates were characterized by very poor activity. As observed for other reactions, the catalytic activity of MgO strongly depends on the pre-treatment temperature. A maximum in activity was observed when MgO was pre-treated at 673 K. At this temperature, decomposition of Mg(OH)2 to MgO is not complete, and Mg(OH)2 remains in the catalyst. It was suggested that the surface OH groups act as active sites, as for the Michael addition reactions described above. 

The pore network connectivity is usually determined by gas sorption analysis [2-4] or mercury intrusion [5] based on percolation theory. Recently, Ismadji and Bhatia [6] have successfully employed the liquid phase adsorption isotherms to determine the pore network connectivity and the pore size distribution of three commercial activated carbons. In our recent study [7], the pore network connectivity of three commercial activated carbons was characterized using liquid phase adsorption isotherms of eight different compounds. In that study we used ester molecules with complex structure, as probe molecules. 

A comparison of the data in Fig. 2 (Plate A, filled circles) and Fig. 5 (Plate B, open symbols) reveals that the performance of the heat-treated wood-based carbon, even under some preloading conditions, is similar to single solute TCE uptake by coal-based activated carbons in the absence of preloading [9]. The observed effect may result from some combination of optimum surface acidity, optimal type of surface functional group, and/or pore structure effects. The WVB carbon has a mesoporous pore structure, which has been observed to minimize the impacts of preloading in preliminary comparative experiments designed to isolate this effect (data not shown). Future work will employ carbon surface characterization techniques that will allow identification of functional groups and more accurate correlation with surface reactivity. 

The carbon selected for study is a coal based, high activity (109 %CTC), extruded carbon (2 mm diameter pellets) from Sutcliffe Speakman (Tarbons Ltd (SSC). The carbon was characterized using N2 adsorption at 77 K and mercury porosimetiy. An analysis of the chemical nature of the carbon surface using the PZC method and Bohem titration revealed that its surface is mostly clean of acidic groups. 

The coke materials discussed so far are made from coal. They are sometimes also called active carbon , if they are employed for purification processes. Capacities as high as 300 Ah/kg are reported in the literature [189]. Some papers are of special interest, for a broad spectrum of graphites and carbons were evaluated in the same laboratory [190,191]. Figure 21 shows that lithium-carbons are characterized by discharge curves with potentials which comprise a broader potential region of 0.1-1V vs. Li. The lithium-graphite potential is held at 0.1-0.3 V vs. Li, as mentioned above. 

Similar studies in an organic solvent yielded almost the same product [66]. Nanostructured particles of amorphous carbon-activated palladium metallic clusters have been prepared (in situ) at room temperature by ultrasound irradiation of an organometallic precursor, tris-//-[dibenzylideneacetone]dipalladium [(p-CH= CH-CO-CH=CH-5 )3Pd2] in mesitylene. Characterization studies show that the product powder consists of nanosize particles, agglomerated in clusters of approximately 800 A. Each particle is found to have a metallic core, covered by a carbonic shell that plays an important role in the stability of the nanoparticles. The catalytic activity in a Heck reaction, in the absence of phosphine ligands, has been demonstrated. 

Huang, Z.H., Kang, F.Y., Huang, W.L., et al. (2002). Pore structure and fractal characteristics of activated carbon fiben characterized by using HRTEM. J. Colloid Interface Sd., 249, 453—7. 

In previous works [8,9], bimetallic Bi-Pd catalysts supported on activated carbon and characterized by various Bi/Pd molar ratios ((Pd+Bi)=10 wt.%) were prepared from the thermal degradation of Bi and Pd acetate-type precursors under nitrogen at 773 K. Because several binary Bi-Pd alloys were heavily suspected in the supported catalysts, three intermetallic compounds, Bi2Pd, BiPd and BiPda were also prepared from the same precursors, according to the same... 

The use of CO2 adsorption at 273 K for the characterization of (ultra)microporous carbons has been repeatedly proposed as an alternative to of Ni at 77 K in view of the well-kimwn activated diffusion limitations to N2 adsorption at 77 K in carbon ultramicropores [28], Mesurement of CO2 adsorption at high pressures [29] afforded a comparison of CO2 (273 K) and N2 (77 K) adsorption at similar adairption potentials, and led to the conclusion that similar mechanisms operate for these two adsorptives at the temperatures indicated. More recently, Lozano-Castelld et al. [30] have reviewed this topic and provided additional examples for the useMness of CO2 adsorption to characterize microporous carbons. Aigon is another usefiil adsorptive for carbon porosity characterization, whose application to ACFs has also been discusssed recently [31]. 

All activated carbons are characterized by their ramified pore system within which various mesopores (r = 1-25 run), micropores (r = 0.4-1.0 run) and submicropores (r < 0.4 nm) each of which branch off from macropores (r > 25 run). 

Nicolas, L., et al. 1992. Nanoscale platinum (0) clusters in glassy carbon Synthesis, characterization, and uncommon catalytic activity. J Am Chem Soc 114 769. 

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