Improving Comparability of Hydrogen Storage Capacities of Nanoporous Materials

Tuesday, November 9, 2010: 3:55 PM
Alta Room (Marriott Downtown)
Valeska P. Ting1, Nuno Bimbo1, Anna Neczaj-Hruzewicz1, Laura Fisher2, Sean P. Rigby1, Andrew D. Burrows2 and Timothy J. Mays1, (1)Department of Chemical Engineering, University of Bath, Bath, United Kingdom, (2)Department of Chemistry, University of Bath, Bath, United Kingdom

One of the primary barriers to the successful and timely implementation of a “Hydrogen Economy” with hydrogen as an energy carrier is the ability to efficiently store hydrogen for later use. The storage of hydrogen via physisorption of H2 onto porous solid state materials benefits from reversible and rapid adsorption and desorption at moderate temperatures and pressures compared to either chemical storage or storage of hydrogen as a compressed gas or cryogenic fluid. The search for the optimal porous solid state storage medium exhibiting acceptably high volumetric and gravimetric densities has long been the focus of intense research. Due to a lack of standardized data collection and analysis routines, it is difficult, if not impossible, to directly compare the hydrogen storage capacities of such materials, as the real material properties cannot be decoupled from the influence of the different data collection or modeling methods used. We present our investigations into producing a standardized routine for the assessment of the hydrogen storage capacities of different nanoporous materials. This includes the formulation of rigorous and systematic data collection routines for the purpose of obtaining universally reproducible H2 isotherms under sub-atmospheric, and high pressure conditions, as well as new methods for modelling the resultant isotherms in order to extract information on the interactions of H2 gas with the porous solid and gain an improved understanding of the physisorption process itself. We will demonstrate these practices, as applied to the analysis of some well-characterized standard materials including commercially-available zeolites and tailored activated carbons materials, as well as applying them to the investigation of the hydrogen uptake capacity of some novel metal-organic frameworks based on mixed ratios of organic ligands, which were synthesized in-house. With this greater knowledge of the variables that affect the quality of hydrogen sorption data, the resultant routines will permit better control of the myriad contributing experimental factors. Combined with the improved data modelling methods, it will become possible to directly compare the hydrogen storage capabilities of any nanoporous materials, a development which will prove invaluable in the evaluation of hydrogen storage materials investigated in the future.

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