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Effect of surface oxygen groups in carbons on hydrogen storage by spillover / Lifeng Wang in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2920–2926 Titre : Effect of surface oxygen groups in carbons on hydrogen storage by spillover Type de document : texte imprimé Auteurs : Lifeng Wang, Auteur ; Frances H. Yang, Auteur ; Ralph T. Yang, Auteur Année de publication : 2009 Article en page(s) : pp. 2920–2926 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  materials  Hydrogen  adsorption  Pd  nanoparticles Résumé : Hydrogen adsorption properties of two different carbon materials (superactivated carbon, AX-21, and graphite oxide) doped with Pd nanoparticles have been studied. The effect of surface oxygen groups in AX-21 on hydrogen storage was investigated, and the results showed Pd supported on oxygen-modified AX-21 (Pd/AX-21-O) had a higher hydrogen storage capacity than Pd supported on unmodified AX-21 (Pd/AX-21). Overall heats of adsorption were obtained from the temperature dependence of the isotherms, and higher values were shown on the oxygen-modified AX-21 sample than the unmodified one, showing that the surface oxygen groups were favorable for hydrogen adsorption. Furthermore, a sample comprising Pd supported on graphite oxide with more surface oxygen (Pd/graphite oxide) was studied. The hydrogen adsorption on this sample showed a hydrogen storage capacity of 0.95 wt % at 100 atm and 298 K. Normalized by the BET surface area, the Pd/graphite oxide exhibited 2.8× the storage capacity of Pd/AX-21-O and 3.4× that of the Pd/AX-21 sample. Molecular orbital calculations showed that the presence of oxygen groups increased the binding energies of the spiltover H on graphite, which is consistent with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014507 [article] Effect of surface oxygen groups in carbons on hydrogen storage by spillover [texte imprimé] / Lifeng Wang, Auteur ; Frances H. Yang, Auteur ; Ralph T. Yang, Auteur . - 2009 . - pp. 2920–2926. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2920–2926 Mots-clés : Carbon  materials  Hydrogen  adsorption  Pd  nanoparticles Résumé : Hydrogen adsorption properties of two different carbon materials (superactivated carbon, AX-21, and graphite oxide) doped with Pd nanoparticles have been studied. The effect of surface oxygen groups in AX-21 on hydrogen storage was investigated, and the results showed Pd supported on oxygen-modified AX-21 (Pd/AX-21-O) had a higher hydrogen storage capacity than Pd supported on unmodified AX-21 (Pd/AX-21). Overall heats of adsorption were obtained from the temperature dependence of the isotherms, and higher values were shown on the oxygen-modified AX-21 sample than the unmodified one, showing that the surface oxygen groups were favorable for hydrogen adsorption. Furthermore, a sample comprising Pd supported on graphite oxide with more surface oxygen (Pd/graphite oxide) was studied. The hydrogen adsorption on this sample showed a hydrogen storage capacity of 0.95 wt % at 100 atm and 298 K. Normalized by the BET surface area, the Pd/graphite oxide exhibited 2.8× the storage capacity of Pd/AX-21-O and 3.4× that of the Pd/AX-21 sample. Molecular orbital calculations showed that the presence of oxygen groups increased the binding energies of the spiltover H on graphite, which is consistent with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014507

Hydrogen storage properties of low--silica type X zeolites / Lifeng Wang in Industrial & engineering chemistry research, Vol. 49 N° 8 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3634–3641 Titre : Hydrogen storage properties of low--silica type X zeolites Type de document : texte imprimé Auteurs : Lifeng Wang, Auteur ; Ralph T. Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 3634–3641 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Hydrogen  Silica  Zeolites Résumé : Hydrogen adsorption properties of low-silica type X zeolites (LSX, Si/Al = 1) containing alkali or alkali-earth metal cations (Li+, Ca2+, and Mg2+) have been studied. It was found that the hydrogen adsorption capacities of LSX zeolites at 77 K were determined mainly by the porosity of the zeolite, while at 298 K, the storage capacities depended on both the H2−cation interactions and the porosity. Among the three exchanged zeolites, Li-LSX had the highest H2 capacity of 1.5 wt % at 77 K and 1 atm, and Ca-LSX had the highest capacity of 0.50 wt % at 298 K and 10 MPa. The hydrogen storage in LSX zeolites via spillover was also investigated. Three methods including bridge building with a catalyst, metal doping via incipient wetness impregnation and metal doping via chemical vapor deposition (CVD) were employed to induce hydrogen spillover, and enhance the storage capacities. Thus, the storage capacities were increased to 0.96−1.2 wt % on the Pt-doped zeolites at 298 K and 10 MPa. The differences between the three methods were compared and discussed. Furthermore, 5 and 10 wt % Ni were doped on Ca-LSX zeolite. The 10 wt % Ni-doped Ca-LSX zeolite showed a storage capacity of 1.15 wt % at 100 atm and 298 K. The important volumetric storage capacities of these zeolites were also estimated based on the densities of the densified zeolites. A 21 g/L portion was obtained for Pt-doped Ca-LSX, and 20 g/L was obtained for Ni-doped Ca-LSX, both at 298 K and 10 MPa. The high volumetric capacities were obtained because of the high densities of zeolites which are substantially higher (2−3 times higher) than that of carbons and metal−organic frameworks. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1003152?prevSearch=Hydrogen%2Bstorage%2Bpr [...] [article] Hydrogen storage properties of low--silica type X zeolites [texte imprimé] / Lifeng Wang, Auteur ; Ralph T. Yang, Auteur . - 2010 . - pp. 3634–3641. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3634–3641 Mots-clés : Hydrogen  Silica  Zeolites Résumé : Hydrogen adsorption properties of low-silica type X zeolites (LSX, Si/Al = 1) containing alkali or alkali-earth metal cations (Li+, Ca2+, and Mg2+) have been studied. It was found that the hydrogen adsorption capacities of LSX zeolites at 77 K were determined mainly by the porosity of the zeolite, while at 298 K, the storage capacities depended on both the H2−cation interactions and the porosity. Among the three exchanged zeolites, Li-LSX had the highest H2 capacity of 1.5 wt % at 77 K and 1 atm, and Ca-LSX had the highest capacity of 0.50 wt % at 298 K and 10 MPa. The hydrogen storage in LSX zeolites via spillover was also investigated. Three methods including bridge building with a catalyst, metal doping via incipient wetness impregnation and metal doping via chemical vapor deposition (CVD) were employed to induce hydrogen spillover, and enhance the storage capacities. Thus, the storage capacities were increased to 0.96−1.2 wt % on the Pt-doped zeolites at 298 K and 10 MPa. The differences between the three methods were compared and discussed. Furthermore, 5 and 10 wt % Ni were doped on Ca-LSX zeolite. The 10 wt % Ni-doped Ca-LSX zeolite showed a storage capacity of 1.15 wt % at 100 atm and 298 K. The important volumetric storage capacities of these zeolites were also estimated based on the densities of the densified zeolites. A 21 g/L portion was obtained for Pt-doped Ca-LSX, and 20 g/L was obtained for Ni-doped Ca-LSX, both at 298 K and 10 MPa. The high volumetric capacities were obtained because of the high densities of zeolites which are substantially higher (2−3 times higher) than that of carbons and metal−organic frameworks. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1003152?prevSearch=Hydrogen%2Bstorage%2Bpr [...]