skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels

Abstract

We report the hydrogen surface excess sorption saturation value of 5.3 wt% at 30 bar pressure at 77 K, from an activated carbon aerogel with a surface area of 3200 m{sup 2}/g as measured by Brunauer-Emmett-Teller (BET) analysis. This sorption value is one of the highest we have measured in a material of this type, comparable to values obtained in high surface area activated carbons. We also report, for the first time, the surface area dependence of hydrogen surface excess sorption isotherms of carbon aerogels at 77 K. Activated carbon aerogels with surface areas ranging from 1460 to 3200 m{sup 2}/g are evaluated and we find a linear dependence of the saturation of the gravimetric density with BET surface area for carbon aerogels up to 2550 m{sup 2}/g, in agreement with data from other types of carbons reported in the literature. Our measurements show these materials to have a differential enthalpy of adsorption at zero coverage of {approx}5 to 7 kJ/mole. We also show that the introduction of metal nanoparticles of nickel improves the sorption capacity while cobalt additions have no effect.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
964101
Report Number(s):
UCRL-JRNL-227848
Journal ID: ISSN 0897-4756; CMATEX; TRN: US200922%%96
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials, vol. 18, no. 26, December 26, 2006, pp. 6085-6087; Journal Volume: 18; Journal Issue: 26
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 25 ENERGY STORAGE; 08 HYDROGEN; ACTIVATED CARBON; ADSORPTION; CAPACITY; CARBON; COBALT ADDITIONS; ENTHALPY; HYDROGEN; HYDROGEN STORAGE; ISOTHERMS; NICKEL; SATURATION; SORPTION; SURFACE AREA

Citation Formats

Kabbour, H, Baumann, T F, Satcher, J H, Saulnier, A, and Ahn, C C. Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels. United States: N. p., 2007. Web.
Kabbour, H, Baumann, T F, Satcher, J H, Saulnier, A, & Ahn, C C. Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels. United States.
Kabbour, H, Baumann, T F, Satcher, J H, Saulnier, A, and Ahn, C C. Mon . "Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels". United States. doi:. https://www.osti.gov/servlets/purl/964101.
@article{osti_964101,
title = {Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels},
author = {Kabbour, H and Baumann, T F and Satcher, J H and Saulnier, A and Ahn, C C},
abstractNote = {We report the hydrogen surface excess sorption saturation value of 5.3 wt% at 30 bar pressure at 77 K, from an activated carbon aerogel with a surface area of 3200 m{sup 2}/g as measured by Brunauer-Emmett-Teller (BET) analysis. This sorption value is one of the highest we have measured in a material of this type, comparable to values obtained in high surface area activated carbons. We also report, for the first time, the surface area dependence of hydrogen surface excess sorption isotherms of carbon aerogels at 77 K. Activated carbon aerogels with surface areas ranging from 1460 to 3200 m{sup 2}/g are evaluated and we find a linear dependence of the saturation of the gravimetric density with BET surface area for carbon aerogels up to 2550 m{sup 2}/g, in agreement with data from other types of carbons reported in the literature. Our measurements show these materials to have a differential enthalpy of adsorption at zero coverage of {approx}5 to 7 kJ/mole. We also show that the introduction of metal nanoparticles of nickel improves the sorption capacity while cobalt additions have no effect.},
doi = {},
journal = {Chemistry of Materials, vol. 18, no. 26, December 26, 2006, pp. 6085-6087},
number = 26,
volume = 18,
place = {United States},
year = {Mon Feb 05 00:00:00 EST 2007},
month = {Mon Feb 05 00:00:00 EST 2007}
}
  • Titania, zirconia, and niobia aerogels were prepared by the sol-gel synthesis from alcoholic metal alkoxide solutions under acidic conditions and the subsequent supercritical drying with carbon dioxide. At a stoichiometric amount of the water and a constant alkoxide concentration the nitric acid contents were varied to examine the characteristics of gel formation behavior and the produced aerogels properties. The range of acid content in which transparent polymeric gels were obtained was determined. under these conditions there was little effect of acid content on the surface area of the calcined aerogel samples. On the other hand, the pore size distributions weremore » significantly affected by the acid contents. The resulting titania, zirconia, and niobia aerogels, after calcination at 773 K for 2h, had BET surface areas of about 200, 100, and 200m{sup 2}/g, respectively, and relatively narrow pore size distributions in the mesopore region. The result suggest a simple way to control the pore sizes of the high-surface-area aerogel only by adjusting the amount of nitric acid used in the sol-gel synthesis. 28 refs., 8 figs., 2 tabs.« less
  • High surface area platinum-titania aerogels with marked meso-to macroporosity have been synthesized via the sol-gel-aerogel route. An acid-catalyzed titania gel was prepared from tetrabutoxy-titanium(IV) with methanol as solvent. The platinum precursor solutions added after the redispersion of the titania gel were either PtCl[sub 4], (NH[sub 4])[sub 2]PtCl[sub 6] or Pt(acac)[sub 2] dissolved in protic solvents. Platinum metal particles formed upon high-temperature supercritical drying. The platinum-titania aerogels have a BET surface area of 150 to 190 m[sup 2] g[sup [minus]1] after thermal pretreatments up to 673 K and the titania matrix consists of well-developed anatase crystallites of about 8-9 nm meanmore » size. Depending on the platinum precursor used, the volume-weighted-mean particle size, determined by TEM, varies in the range 3.6 to 68 nm, consistent with XRD results for the platinum component. All aerogel samples showed a pronounced stability of both the titania matrix and the platinum particles towards air or hydrogen at temperatures up to 673 K. Thermal analysis, combined with mass spectroscopy, revealed that the untreated catalysts contain a considerable amount of entrapped organic impurities after the high-temperature supercritical drying. For the characterization of the activity and the accessibility of platinum particles the liquid phase hydrogenations of trans-stilbene and benzophenone were used as test reactions. Compared to a commercial alumina-supported platinum catalyst, the untreated 2-5 wt% platinum-titania catalysts derived from (NH[sub 4])[sub 2]PtCl[sub 6]- and especially PtCl[sub 4]-precursor solutions exhibit a markedly higher catalytic activity. In general, air pretreatments at 573 K or above had either no or promoting influence on activity. In contrast, pretreatments in hydrogen produced either no or detrimental activity change. 50 refs., 9 figs., 3 tabs.« less
  • Alumina aerogels were prepared through the addition of propylene oxide to aqueous or ethanolic solutions of hydrated aluminum salts, AlCl{sub 3} {center_dot} 6H{sub 2}O or Al(NO{sub 3}){sub 3} {center_dot} 9H{sub 2}O, followed by drying with supercritical CO{sub 2}. This technique affords low-density (60-130 kg/m{sup 3}), high surface area (600-700 m{sup 2}/g) alumina aerogel monoliths without the use of alkoxide precursors. The dried alumina aerogels were characterized using elemental analysis, high-resolution transmission electron microscopy, powder X-ray diffraction, solid state NMR, acoustic measurements and nitrogen adsorption/desorption analysis. Powder X-ray diffraction and TEM analysis indicated that the aerogel prepared from hydrated AlCl{sub 3}more » in water or ethanol possessed microstructures containing highly reticulated networks of pseudoboehmite fibers, 2-5 nm in diameter and of varying lengths, while the aerogels prepared from hydrated Al(NO{sub 3}){sub 3} in ethanol were amorphous with microstructures comprised of interconnected spherical particles with diameters in the 5-15 nm range. The difference in microstructure resulted in each type of aerogel displaying distinct physical and mechanical properties. In particular, the alumina aerogels with the weblike microstructure were far more mechanically robust than those with the colloidal network, based on acoustic measurements. Both types of alumina aerogels can be transformed to {gamma}-Al{sub 2}O{sub 3} through calcination at 800 C without a significant loss in surface area or monolithicity.« less
  • Vanadium pentoxide gels have been obtained from decavanadic acid prepared by ion exchange on a resin from ammonium metavanadate solution. The progressive removal of water by solvent exchange in supercritical conditions led to the formation of high surface area V{sub 2}O{sub 5}, 1.6H{sub 2}O aerogels. Heat treatment under ammonia has been performed on these aerogels in the 450-900 deg. C temperature range. The oxide precursors and oxynitrides have been characterized by XRD, SEM, TGA, BET. Nitridation leads to divided oxynitride powders in which the fibrous structure of the aerogel is maintained. The use of both very low heating rates andmore » high surface area aerogel precursors allows a higher rate and a lower threshold of nitridation than those reported in previous works. By adjusting the nitridation temperature, it has been possible to prepare oxynitrides with various nitrogen enrichment and vanadium valency states. Whatever the V(O,N) composition, the oxidation of the oxynitrides in air starts between 250 and 300 deg. C. This determines their potential use as chemical gas sensors at a maximum working temperature of 250 deg. C.« less