Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session J39: Focus Session: Hydrogen Storage I |
Hide Abstracts |
Sponsoring Units: FIAP DMP Chair: Gregory Meisner, General Motors R&D Room: Colorado Convention Center 502 |
Tuesday, March 6, 2007 11:15AM - 11:51AM |
J39.00001: Strategies for increasing hydrogen storage capacity and adsorption energy in MOFs Invited Speaker: Storage of hydrogen in its molecular form is difficult and expensive because it requires employing either extremely high pressures as a gas or very low temperatures as a liquid. Worldwide effort is focused on storage of hydrogen with sufficient efficiency to allow its use in stationary and mobile fueling applications. DOE has set performance targets for on-board automobile storage systems to have densities of 60 mg H$_{2}$/g (gravimetric) and 45 g H$_{2}$/L (volumetric) for year 2010. These are system goals. Metal-organic frameworks (MOFs) have recently been identified as promising adsorbents (physisorption) for H$_{2}$ storage, although little data are available for their adsorption behavior at saturation: a critical parameter for gauging the practicality of any material. This presentation will report adsorption data collected for seven MOF materials at 77 K which leads to saturation at pressures between 25 and 80 bar with uptakes from 2{\%} to 7.5{\%}. Strategies for increasing the adsorption energy of hydrogen in MOFs will also be presented. [Preview Abstract] |
Tuesday, March 6, 2007 11:51AM - 12:03PM |
J39.00002: Structure, lattice dynamics, and hydrogen adsorption properties of zeolitic imidazolate framework-8 W. Zhou, H. Wu, T. Yildirim Zeolitic imidazolate frameworks (ZIFs) are a new family of nanoporous metal-organic framework compounds that possess interesting zeolite-type structures with very high chemical stability [1,2]. We performed high-pressure isotherm measurements at various temperatures to characterize the H$_{2}$ adsorption properties of ZIF8, which consists of ZnN$_{4}$ clusters linked by 2-methylimidazole [H$_{2}$C$_{3}$N$_{2}$-(CH$_{3})$]. We find that the adsorption capacity is 1.2 wt{\%} at 77 K and 1 atm, while the maximal adsorption is 4.5 wt{\%} at 30~K and 3 atm. The initial heat of adsorption is $\sim $5 kJ/mol. Using neutron powder diffraction, we investigated the structure of ZIF8 and its associated hydrogen adsorption sites. These sites were directly determined using difference Fourier analysis and agree well with first-principles predictions. Furthermore, we studied the structural stability and lattice dynamics of ZIF8, combining inelastic neutron scattering and first-principles calculations. Several interesting phonon modes were identified. [1] X. C. Huang et al., Angew. Chem. Int. Ed. 45, 1557 (2006). [2] K. S. Park et al., Proc. Natl. Acad. Sci. U.S.A. 103, 10186 (2006). [Preview Abstract] |
Tuesday, March 6, 2007 12:03PM - 12:15PM |
J39.00003: Quantum methyl rotations in zeolitic imidazolate framework-8: Inelastic neutron scattering and first-principles calculations J. J. Rush, W. Zhou, H. Wu, T. J. Udovic, T. Yildirim Zeolitic imidazolate framework-8 (ZIF8), which consists of ZnN$_{4}$ clusters linked by 2-methylimidazole [H$_{2}$C$_{3}$N$_{2}$-(CH$_{3})$], is a newly discovered framework compound with interesting hydrogen-adsorption properties. The presence of a single type of methyl group in its crystal structure renders ZIF8 an ideal system for studying quantum methyl rotations. Combining inelastic neutron scattering measurements and first-principles calculations, we studied the quantum rotational tunneling and phonons associated with the ZIF8 methyl groups. The rotational tunnel splitting is an extremely sensitive probe of the local potential. The measured tunnel splitting ($\sim $345 $\mu $eV at 1.4~K) indicated a nearly free quantum rotor ($i.e.$, a very low methyl rotational barrier), which is unusual for the solid state. With guest molecules adsorbed inside the framework, the rotational barrier was found to change significantly. Hydrogen adsorption decreased the barrier at low loading, yet increased it at higher loading. Methane adsorption nearly doubled the rotational barrier. These results provided clues for understanding the nature of the ZIF-guest molecule interactions. [Preview Abstract] |
Tuesday, March 6, 2007 12:15PM - 12:27PM |
J39.00004: Hydrogen molecule binding to unsaturated metal sites in metal-organic frameworks studied by neutron powder diffraction and inelastic neutron scattering Yun Liu, Craig Brown, Dan Neumann, Mircea Dinca, Jeffrey Long, Vanessa Peterson, Cameron Kepert Metal organic framework (MOF) materials have shown considerable potential for hydrogen storage arising from very large surface areas. However, the low binding energy of hydrogen molecules limits its storage capability to very low temperatures ($<$ 77 K), which is impractical for industrial applications. Using neutron powder diffraction (NPD), we have characterized the hydrogen adsorption sites in a selected series of MOF materials with exposed unsaturated metal ions. Direct binding between the unsaturated metal ions and hydrogen molecules is observed and responsible for the enhanced initial hydrogen adsorption enthalpy. The different metals centers in these MOFs show different binding strength and interaction distances between the hydrogen molecule and metal ions. The organic linker also affects the overall H$_{2}$ binding strength. Inelastic neutron scattering spectra of H$_{2}$ in these MOFs are also discussed. [Preview Abstract] |
Tuesday, March 6, 2007 12:27PM - 12:39PM |
J39.00005: Infrared spectroscopy of trapped hydrogen in metal-organic-frameworks Stephen FitzGerald, Kelty Allen, Patrick Landerman, Jesse Rowsell We present a novel use of diffuse reflectance infrared spectroscopy to study the quantum dynamics of molecular hydrogen trapped within metal-organic-framework (MOF) hosts. This technique is particularly useful in the context of hydrogen storage since it provides detailed information about the intermolecular potential at the binding site. The spectra consist of quite sharp bands associated with the quantized vibrational and rotational motion of the trapped hydrogen. The vibrational bands are redshifted relative to the gas phase while the rotational sidebands contain an additional fine structure due to the orientational dependence of the binding potential. Results on MOF-5 reveal the presence of two primary binding sites. The first saturates at a loading concentration on the order of 4 {H$_{2} $} per Zn ion and has a binding energy of roughly 4 kJ/mole. The second has a somewhat lower binding energy. Both site produce an ortho to para conversion rate on the order of 30-50 \% per hour. [Preview Abstract] |
Tuesday, March 6, 2007 12:39PM - 12:51PM |
J39.00006: Gas separation using novel materials: kinetics of gas adsorption on RPM-1 and Cu-BTC metal-organic frameworks~ Kathleen Lask, Vaiva Krungleviciute, Aldo Migone, J.-Y. Lee, Jing Li We have measured the adsorption kinetics of two gases, freon and argon, on two microporous metal-organic framework materials, RPM-1 (or [Co$_{3}$(bpdc)$_{3}$bpy]$\cdot $4DMF$\cdot $H$_{2}$O, bpdc = biphenyldicarboxylate) and Cu-BTC (or [Cu$_{3}$(btc)$_{2}$(H$_{2}$O)$_{3}$], btc = benzenetricarboxylate). The measurements were conducted at comparable values of the scaled temperatures (T$_{isotherm}$/T$_{critical})$ for the respective gases. In our experiments, we monitor the pressure decrease as a function of time after a dose of gas is admitted into the experimental cell. The kinetics results obtained for both gases are similar on Cu-BTC, while they are significantly different in RPM-1. Our results indicate that RPM-1 has potential for gas separation for mixtures of species with dimensions similar to argon and freon; this is not the case for Cu-BTC MOF. [Preview Abstract] |
Tuesday, March 6, 2007 12:51PM - 1:03PM |
J39.00007: ABSTRACT WITHDRAWN |
Tuesday, March 6, 2007 1:03PM - 1:15PM |
J39.00008: High Pressure Volumetric Sorption Measurements On Small Samples At Low Temperatures Philip Parilla, Linn Simpson, Jeff Blackburn, Anne Dillon, Michael Heben With recent efforts to develop new hydrogen storage materials needed for the hydrogen economy, fast and accurate hydrogen capacity measurements are needed to screen the numerous types of test samples. Having an ability to perform such measurements on small masses facilitates the research both by reducing the effort required to produce enough material for testing and by increasing measurement throughput since small samples have process faster. Here, we report on improvements to the volumetric method that allows measurements at high pressures ($\sim $ 80 bar) and low temperature (77 K). Critical components for the exact control of temperature gradients from room temperature to the LN2 bath as well as methods used to minimize the effect of the falling LN2 level will be described. Experimental procedure, instrument calibration, accuracy estimates, and instrument verification will be discussed. Finally, example data with samples will be used to show the functioning of the instrument. [Preview Abstract] |
Tuesday, March 6, 2007 1:15PM - 1:27PM |
J39.00009: Novel H2 Sorption Measurements of Nanostructured Materials Lin Simpson, Phillip Parilla, Jeff Blackburn, Kevin O'Neill, Michael Sanders, Anne Dillon, Erin Whitney, Michael Heben, Thomas Gennett To expeditiously develop nanostructured materials with high hydrogen sorption capacities, a novel volumetric measurement apparatus was designed and constructed that is suitable for rapid analysis of the small samples (milligram) typically available in the laboratory. The instrument enables both low temperature (down to $\sim $12K) volumetric measurements and high temperature (up to 1300K) sample processing without the need for sample transfers. The instrument has been used to study the hydrogen sorption behavior of chemically and thermally processed raw and purified nanostructured materials (e.g. nanotubes, activated carbons, polymers, aerogels). Hydrogen sorption, specific surface area, and binding energy results for different samples will be reported. The goal of these activities is to engineer hydrogen sorption materials that can ultimately meet the DOE's targets for vehicular fuel cell applications. Funding for this effort provided by the DOE's EERE Hydrogen Program within the Center of Excellence on Carbon-based Hydrogen Storage Materials, and by the Office of Science, Basic Energy Sciences, Materials Science and Engineering under subcontract DE-AC36-99GO10337 to NREL. [Preview Abstract] |
Tuesday, March 6, 2007 1:27PM - 1:39PM |
J39.00010: Hydrogen Adsorption in Carbon-Based Materials Studied by NMR Yue Wu, Alfred Kleinhammes, Robert Anderson, Shenghua Mao Hydrogen adsorption in carbon-based materials such as boron-doped graphite and boron-doped single-walled carbon nanotubes (SWNTs) were investigated by nuclear magnetic resonance (NMR). $^{1}$H NMR is shown to be a sensitive and quantitative probe for detecting adsorbed gas molecules such as H$_{2}$, methane, and ethane. NMR measurements were carried out in-situ under given H$_{2}$ pressure up to a pressure of over 100 atm. From such $^{1}$H NMR measurement, the amount of adsorbed H$_{2}$ molecules was determined versus pressure. This gives an alternative method for measuring the adsorption isotherms where the H$_{2}$ signature is identified based on spin properties rather than weight or volume as in gravimetric and volumetric measurements. The measurement shows that boron doping has a favorable effect on increasing the adsorption enthalpy of H$_{2}$ in carbon-based systems. This work was done in collaboration with NREL and Department of Chemistry, University of Pennsylvania, within the DOE Center of Excellence on Carbon-based Hydrogen Storage Materials and is supported by DOE. [Preview Abstract] |
Tuesday, March 6, 2007 1:39PM - 1:51PM |
J39.00011: In-situ electronic structure study of H$_2$ adsorption on HOPG Per-Anders Glans, Jinghua Guo The storage of hydrogen in a both safe and compact manner is of great importance for, for example, hydrogen powered vehicles. Interesting candidates for dense storage of hydrogen are different types of carbon based nanomaterials: single (SWCNT) and multi-walled carbon nanotubes, C$_{60}$ and C$_{70}$. Various groups have reported different amounts of hydrogen stored using SWCNTs. Highly ordered pyrolytic graphite (HOPG) has similarities with the carbon systems mentioned above. Photon-in, photon-out techniques are well suited for measurements of the electronic structure of these materials under ambient hydrogen pressure. X-ray absorption (XAS) and emission spectroscopy (XES) measurements have been performed on HOPG under different hydrogen pressures. The measured partial density of states of this system will be presented. [Preview Abstract] |
Tuesday, March 6, 2007 1:51PM - 2:03PM |
J39.00012: Hydrogen Adsorption on Nanoporous Biocarbon M.B. Wood, J.W. Burress, C.M. Lapilli, P. Pfeifer, P.S. Shah, G.J. Suppes, A.C. Dillon, P.A. Parilla As a part of the Alliance for Collaborative Research in Alternative Fuel Technology (http://all-craft.missouri.edu) we study activated carbons made from corncob, optimized for storing methane and hydrogen (H2) by physisorption at low pressure. We report here: (a) storage capacities of 73-91 g H2/kg carbon at 77 K and 47 bar, validated in three different laboratories (the 2010 DOE target is 60 g H2/kg system); (b) binding energies from H2 adsorption isotherms (c) temperature-programmed desorption data; (d) degree of graphitization of the carbon surface from Raman spectra; (e) pore structure of carbon from nitrogen and methane adsorption isotherms, and small-angle x-ray scattering. The structural analysis shows that the carbon is highly microporous and that the pore space is highly correlated (micropores do not scatter independently). [Preview Abstract] |
Tuesday, March 6, 2007 2:03PM - 2:15PM |
J39.00013: Adsorption of supercritical carbon dioxide and propane in porous aerogel Yuri Melnichenko, Gernot Rother, George Wignall, David Cole, Henrich Frielinghaus We demonstrate that small-angle neutron scattering (SANS) can be used to determine the density and volume fraction of the adsorbed fluid phase in porous materials. The developed methodology is used to study the adsorption of near-critical CO2 and propane in aerogel as a function of pressure and temperature. For the first time the variation of the density and volume fraction of the adsorbed phase of near-critical fluids is reported and analyzed. These parameters are used to determine the absolute fluid adsorption without additional assumptions commonly used in the literature. The adsorption of CO2 and propane (8 g/g and 1 g/g, respectively) is found to be significantly higher in aerogels than in activated carbons and silica gels. The results provide new insights in the adsorption behavior of supercritical fluids, such as a non-monotonic variation of the density of the adsorbed phase and depletion of aerogel at high pressures. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700