Show simple item record Anderson, RJ McNicholas, TP Kleinhammes, A Wang, A Liu, J Wu, Y
dc.coverage.spatial United States 2011-06-21T17:26:25Z 2010-06-30
dc.identifier.citation J Am Chem Soc, 2010, 132 (25), pp. 8618 - 8626
dc.description.abstract (1)H NMR spectroscopy is used to investigate a series of microporous activated carbons derived from a poly(ether ether ketone) (PEEK) precursor with varying amounts of burnoff (BO). In particular, properties relevant to hydrogen storage are evaluated such as pore structure, average pore size, uptake, and binding energy. High-pressure NMR with in situ H(2) loading is employed with H(2) pressure ranging from 100 Pa to 10 MPa. An N(2)-cooled cryostat allows for NMR isotherm measurements at both room temperature ( approximately 290 K) and 100 K. Two distinct (1)H NMR peaks appear in the spectra which represent the gaseous H(2) in intergranular pores and the H(2) residing in micropores. The chemical shift of the micropore peak is observed to evolve with changing pressure, the magnitude of this effect being correlated to the amount of BO and therefore the structure. This is attributed to the different pressure dependence of the amount of adsorbed and non-adsorbed molecules within micropores, which experience significantly different chemical shifts due to the strong distance dependence of the ring current effect. In pores with a critical diameter of 1.2 nm or less, no pressure dependence is observed because they are not wide enough to host non-adsorbed molecules; this is the case for samples with less than 35% BO. The largest estimated pore size that can contribute to the micropore peak is estimated to be around 2.4 nm. The total H(2) uptake associated with pores of this size or smaller is evaluated via a calibration of the isotherms, with the highest amount being observed at 59% BO. Two binding energies are present in the micropores, with the lower, more dominant one being on the order of 5 kJ mol(-1) and the higher one ranging from 7 to 9 kJ mol(-1).
dc.format.extent 8618 - 8626
dc.language eng
dc.language.iso en_US en_US
dc.relation.ispartof J Am Chem Soc
dc.relation.isversionof 10.1021/ja9109924
dc.title NMR methods for characterizing the pore structures and hydrogen storage properties of microporous carbons.
dc.title.alternative en_US
dc.type Journal Article
dc.description.version Version of Record en_US 2010-6-30 en_US
duke.description.endpage 8626 en_US
duke.description.issue 25 en_US
duke.description.startpage 8618 en_US
duke.description.volume 132 en_US
dc.relation.journal Journal of the American Chemical Society en_US
pubs.issue 25
pubs.organisational-group /Duke
pubs.organisational-group /Duke/Trinity College of Arts & Sciences
pubs.organisational-group /Duke/Trinity College of Arts & Sciences/Chemistry
pubs.publication-status Published
pubs.volume 132
dc.identifier.eissn 1520-5126

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