Activated carbon fibers characterization

Cazorla-Amords, D., dc Lecea, C. S. M., Alcaniz-Monge, J., Gardner, M., North, A. and Dore, J., Characterization of activated carbon fibers by small-angle x-ray scattering. Carbon, 1998, 36(3), 309 312. 

Cazorla-Amoros, D., Alcaniz-Mongc, J. and Linares-Solano, A., Characterization of activated carbon fibers by COj adsorption, Langmuir, 1996, 12(11), 2820 2824. 

Tanahashi, 1., Yoshida, A. and Nishino, A., Electrochemical characterization of activated carbon fiber cloth polarizable electrodes for electric double layer capacitors. J. Electrochem. Soc., 1990, 137(10), 3052 3056. 

Cazorla-Amoros D, Alcafiiz-Monge J, Linares-Solano A. Characterization of Activated Carbon Fibers by CO2 Adsorption. Langmuir 1996 12(11 ) 2820-2824. 

Yang, C.M., El-Merraoui, M., Seki, H., and Kaneko, K. Characterization of nitrogen-alloyed activated carbon fiber. Langmuir 17, 2001 675-680. 

Raymundo-Pinero, E., Cazorla-Amoros, D., Linares-Solano, A., Find, J., Wild, U., and Schlogl, R. Structural characterization of N-containing activated carbon fibers prepared from a low softening point petroleum pitch and a melamine resin. Carbon 40, 2002 597-608. 

In this chapter, we present in some detail gas adsorption techniques, by reviewing the adsorption theory and the analysis methods, and present examples of assessment of PSDs with different methods. Some examples will show the limitations of this technique. Moreover, we also focus on the use of SAXS technique for the characterization of porous solids, including examples of SAXS and microbeam small-angle x-ray scattering (pSAXS) applications to the characterization of activated carbon fibers (ACFs). We remark the importance of combining different techniques to get a complete characterization, especially when not accessible porosity exists. 

Lozano-Castello D, Cazorla-Amoros D, Linares-Solano A, Hall PJ, and Fernandez JJ. Characterization of activated carbon fibers by positron annihilation lifetime spectroscopy (PALS). In Unger KK, et al., eds. Studies in Surface Science and Catalysis, Characterisation of Porous Solids V, vol. 128, the Netherlands Elsevier Science. 2000 523-532. 

Lozano-Castello D, Raymundo-Pinero E, Cazorla-Amoros D, Linares-Solano A, Muller M, and Riekel C. Characterization of pore distribution in activated carbon fibers by microbeam small angle x-ray scattering. Carbon, 2002 40 2727-2735. 

A test matrix of about 20 different carbon samples, including commercial carbon fibers and fiber composites, graphite nanofibers, carbon nanowebs and single walled carbon nanotubes was assembled. The sorbents were chosen to represent a large variation in surface areas and micropore volumes. Both non-porous materials, such as graphites, and microporous sorbents, such as activated carbons, were selected. Characterization via N2 adsorption at 77 K was conducted on the majority of the samples for this a Quantachrome Autosorb-1 system was used. The results of the N2 and H2 physisorption measurements are shown in Table 2. In the table CNF is used to designate carbon nanofibers, ACF is used for activated carbon fibers and AC for activated carbon. 

Ishii, C., et al. (1997). Structural characterization of heat-treated activated carbon fibers, J. Porous Materials. 4, 3, 181-186. 

Microbeam small angle X-ray scattering ( SAXS) a novel technique for the characterization of activated carbon fibers. 

In this sense, the main objective of this work is to show the usefulness of the Microfocus Beamline (ID 13) in the characterization of activated carbon fibers. Thus, examples with activated carbon fibers with different bum-off degree obtained with different activating agents, and different fiber diameter will be presented. 

In order to show the suitability of the pSAXS technique to characterize activated carbon fibers, the examples have been divided in two sections i) experiments at the center of the fiber, and ii) experiments across the fiber diameter. 

These results constitute a direct proof of the different behavior of CO2 and steam as activating agents, and show the suitability of this novel experiments for characterizing different regions of activated carbon fibers. 

The examples presented in this work illustrate the suitability of pSAXS technique to characterize activated carbon fibers. It has been shown the isotropy features in activated carbon fibers prepared from different precursors and using different activating agents. In addition, this technique is able to obtain scattering measurements across the fiber diameter, which has allows us to obtain maps of pores distribution. The present results show that... 

Chemically activated carbon fibers (CACF) manufactured KOH impregnated to ACF and confirmed selective adsorption conduct of NO and NO in fixed bed adsorption column. NOx desorption studied on He at Stl/min up to SOOC using temperature programmed desorption (TPD), and observed surface characteristic at absorption-desorption. CACF was increased adsorptivity with offers selective adsorptivity by KOH in NOx adsorption, and CACF (KOH ACF == I 3) had an adsorptivity that was four times higher than that of ACF. NOx desorption on ACF was mostly occurred within 200 C. The results of surface characterization were found that NOx was produced as a KNOx(x=2,3) after adsorption and potassium ions were distributed without loss after desorption. 

Characterization of activated carbon fibers by Positron Annihilation Lifetime Spectroscopy (PALS). 

The use of Positron Annihilation Lifetime Spectroscopy (PALS) technique to characterize porous carbon materials has been analyzed. Positron annihilation lifetimes have been measured in two series of petroleum pitch-based activated carbon fibers (ACF) prepared by CO2 and steam activation. Two lifetime components were found a short-lived component, Ti from 375 to 393 ps and a long-lived component, 1 2 from 1247 to 1898 ps. The results have been compared to those obtained by Small Angle X-Ray Scattering (SAXS) and N2 and CO2 adsorption at 77K and 273K respectively The correlation found demonstrates the usefulness of PALS to get complementary information on the porous structure of microporous carbons. 

In the present work, positron annihilation lifetime spectroscopy has been applied to characterize the porosity of activated carbons fibers. These materials are essentially microporous [16], with slit shaped pores and with a homogeneous pore size distribution. Because of that, they seem to be the most appropriate materials to analyze the application of PALS technique to the characterization of porous carbon materials. 

Activated carbon fibers essentially microporous and with well-developed porosity have been used to asses the suitability of PALS to characterize microporous carbons. The lifetime spectra of the ACFs present two components. The first one with lifetime Ti = 375-395 ps corresponds to the annihilation of positrons with electrons at the surface of the pores. The second component with lifetime T2 = 1200-1900 ps corresponds to the annihilation of o-Ps. 

Wan, Y.Z., Wang, Y.L., Cheng, G.X., et al. (2001). Preparation and characterization of activated carbon fiber supporting silver-loaded mesoporous molecular sieves. Carbon, 39, 1605—16. 

Lozano-CasteUo, D., Raymundo-Pinero, E., Cazorla-Amoros, D., et al. (2002). Microbeam small angle X-ray scattering (fJtSAXS) a novel technique for the characterization of activated carbon fibers. Stud. Surf. Sd. Catal., 144, 51—8. 

---