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Hydrogen Adsorption (hydrogen + adsorption)

Distribution by Scientific Domains
Chemistry62%

Selected Abstracts

Network Topology of a Hybrid Organic Zinc Phosphate with Bimodal Porosity and Hydrogen Adsorption,

ANGEWANDTE CHEMIE, Issue 33 2009
Shu-Hao Huang
Füll,s auf! Ein nanoporöses hybrides Zinkphosphat (siehe Bild; ,[Zn2PO4]-Säulen in Dunkelblau) mit in die Struktur integrierten organischen Liganden (Amin: grau; Arylcarboxylat: cyan) weist eine ungewöhnliche bimodale Porosität und Wasserstoffgas-Speicherfähigkeit auf. [source]

Hydrogen Adsorption and Diffusion in p - tert -Butylcalix[4]arene: An Experimental and Molecular Simulation Study

CHEMISTRY - A EUROPEAN JOURNAL, Issue 38 2010
Dr. Saman Alavi
Abstract Experimental adsorption isotherms were measured and computer simulations were performed to determine the nature of the H2 gas uptake in the low-density p - tert -butylcalix[4]arene (tBC) phase. 1H,NMR peak intensity measurements for pressures up to 175,bar were used to determine the H2 adsorption isotherm. Weak surface adsorption (up to ,2,mass,% H2) and stronger adsorption (not exceeding 0.25,mass,% or one H2 per calixarene bowl) inside the calixarene phase were detected. The latter type of adsorbed H2 molecule has restricted motion and shows a reversible gas adsorption/desorption cycle. Pulsed field gradient (PFG) NMR pressurization/depressurization measurements were performed to study the diffusion of H2 in the calixarene phases. Direct adsorption isotherms by exposure of the calixarene phase to pressures of H2 gas to ,60,bar are also presented, and show a maximum H2 adsorption of 0.4,H2 per calixarene bowl. Adsorption isotherms of H2 in bulk tBC have been simulated using grand canonical Monte Carlo calculations in a rigid tBC framework, and yield adsorptions of ,1,H2 per calixarene bowl at saturation. Classical molecular dynamics simulations with a fully flexible calixarene molecular force field are used to determine the guest distribution and inclusion energy of the H2 in the solid with different loadings. [source]

Computational Investigation of Hydrogen Adsorption by Alkali-Metal-Doped Organic Molecules: Role of Aromaticity

CHEMPHYSCHEM, Issue 2 2009
Kancharlapally Srinivasu
Abstract Hydrogen storage: Simple organic molecular systems (CnHn, n=4, 5, 6, 8) are proposed for hydrogen storage purposes based on the concept of aromaticity. The adsorption of hydrogen is attributed to pronounced charge transfer from the sodium atom (green, see picture) to the organic systems and the electrostatic interaction between the ion and hydrogen molecules. Theoretical studies on hydrogen adsorption in small organic molecular systems, such as cyclobutadiene (C4H4), the cyclopentadienyl radical (C5H5), benzene (C6H6), and cyclooctatetraene (C8H8) and their metal-doped modifications, are carried out. Our results reveal that the simple van der Waals surfaces of pure organic molecules are not good enough for hydrogen adsorption due to the weak interaction between hydrogen molecules and the organic molecular surface. However, doping of alkali-metal atoms in the above organic molecular systems increases their hydrogen adsorption ability significantly, mainly due to electron transfer from the metal atom to the carbon surface. This charged surface created around the metal atom is found to enhance the hydrogen adsorption capacity of the complex considerably, both in terms of interaction energy and the number of adsorbed hydrogen molecules, with a hydrogen adsorption capacity ranging from 10 to 12 wt,%. The role of aromaticity in such molecular systems is important in stabilizing these ionized organo-alkali-metal complexes. [source]

Exploiting the Kubas Interaction in the Design of Hydrogen Storage Materials

ADVANCED MATERIALS, Issue 18 2009
Tuan K. A. Hoang
Abstract Hydrogen adsorption and storage using solid-state materials is an area of much current research interest, and one of the major stumbling blocks in realizing the hydrogen economy. However, no material yet researched comes close to reaching the DOE 2015 targets of 9,wt% and 80,kg,m,3 at this time. To increase the physisorption capacities of these materials, the heats of adsorption must be increased to ,20,kJ,mol,1. This can be accomplished by optimizing the material structure, creating more active species on the surface, or improving the interaction of the surface with hydrogen. The main focus of this progress report are recent advances in physisorption materials exhibiting higher heats of adsorption and better hydrogen adsorption at room temperature based on exploiting the Kubas model for hydrogen binding: (,2 -H2),metal interaction. Both computational approaches and synthetic achievements will be discussed. Materials exploiting the Kubas interaction represent a median on the continuum between metal hydrides and physisorption materials, and are becoming increasingly important as researchers learn more about their applications to hydrogen storage problems. [source]

Modelling CO poisoning and O2 bleeding in a PEM fuel cell anode

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2003
J.J. Baschuk
Abstract Fuel gas containing carbon monoxide severely degrades the performance of a polymer electrolyte membrane (PEM) fuel cell. However, CO poisoning can be mitigated by introducing oxygen into the fuel (oxygen bleeding). A mathematical PEM fuel cell model is developed that simulates both CO poisoning and oxygen bleeding, and obtains excellent agreement with published, experimental data. Modelling efforts indicate that CO adsorption and desorption follow a Temkin model. Increasing operating pressure or temperature mitigates CO poisoning, while use of reformate fuel increases the severity of the poisoning effect. Although oxygen bleeding mitigates CO poisoning, an unrecoverable performance loss exists at high current densities due to competition for reaction sites between hydrogen adsorption and the heterogeneous catalysis of CO. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Investigation of Hydrogen Physisorption Active Sites on the Surface of Porous Carbonaceous Materials

CHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2008
Deyang Qu
Abstract Hydrogen physisorption in different carbonaceous materials was investigated in liquid nitrogen (77,K). The total hydrogen adsorption was found to have a linear relationship with the surface area of pores <30,Å. The surface area and porosity of the carbon materials were determined by dinitrogen adsorption at 77,K and density function theory (DFT). The active sites for hydrogen adsorption were investigated and found to be related to the edge orientation of defective graphene micro-sheet domains. [source]

Computational Investigation of Hydrogen Adsorption by Alkali-Metal-Doped Organic Molecules: Role of Aromaticity

CHEMPHYSCHEM, Issue 2 2009
Kancharlapally Srinivasu
Abstract Hydrogen storage: Simple organic molecular systems (CnHn, n=4, 5, 6, 8) are proposed for hydrogen storage purposes based on the concept of aromaticity. The adsorption of hydrogen is attributed to pronounced charge transfer from the sodium atom (green, see picture) to the organic systems and the electrostatic interaction between the ion and hydrogen molecules. Theoretical studies on hydrogen adsorption in small organic molecular systems, such as cyclobutadiene (C4H4), the cyclopentadienyl radical (C5H5), benzene (C6H6), and cyclooctatetraene (C8H8) and their metal-doped modifications, are carried out. Our results reveal that the simple van der Waals surfaces of pure organic molecules are not good enough for hydrogen adsorption due to the weak interaction between hydrogen molecules and the organic molecular surface. However, doping of alkali-metal atoms in the above organic molecular systems increases their hydrogen adsorption ability significantly, mainly due to electron transfer from the metal atom to the carbon surface. This charged surface created around the metal atom is found to enhance the hydrogen adsorption capacity of the complex considerably, both in terms of interaction energy and the number of adsorbed hydrogen molecules, with a hydrogen adsorption capacity ranging from 10 to 12 wt,%. The role of aromaticity in such molecular systems is important in stabilizing these ionized organo-alkali-metal complexes. [source]