scholarly journals Molecular Simulation of Hydrogen Storage in Ion-Exchanged X Zeolites

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Xiaoming Du
Keyword(s):  
Adsorption Capacity ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Adsorption Temperature ◽  
X Zeolites ◽  
Cation Type ◽  
Simulated Distribution

Grand Canonical Monte Carlo (GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on ion-exchanged X zeolites at 100–293 K and pressures up to 10 MPa in this paper. The effect of cation type, temperature, and pressure on hydrogen adsorption capacity, heat of adsorption, adsorption sites, and adsorption potential energy of ion-exchanged X zeolites was analyzed. The results indicate that the hydrogen adsorption capacity increases with the decrease in temperatures and the increase in pressures and decreases in the order ofKX<LiX<CaX. The isosteric heat of adsorption for all the three zeolites decreases appreciably with the increase in hydrogen adsorption capacity. The hydrogen adsorption sites in the three zeolites were determined by the simulated distribution of hydrogen adsorption energy and the factors that influence their variations were discussed. Adsorption temperature has an important effect on the distribution of hydrogen molecules in zeolite pores.

Determination of the Isosteric Heat of Adsorption of Hydrogen on the Multi-Walled Carbon Nanotubes

2012 ◽  
Vol 512-515 ◽  
pp. 1484-1491 ◽  
Author(s):  
Qing Rong Zheng ◽  
Shuai Gao ◽  
Chen Jie
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Step Method ◽  
Surface Loading ◽  
Isosteric Heat Of Adsorption ◽  
Hydrogen Molecules ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The isosteric heat of adsorption was used to study the interaction between hydrogen molecules and the Multi-Walled Carbon Nanotubes (MWCNTs). Characterizations of the MWCNTs sample were carried out based on the N2 adsorption isotherm at 77 K and the images from TEM and HRTEM. Step by step method was used to volumetrically measure hydrogen adsorption isotherms at equilibrium temperature-pressures from 123-310 K and 0-12.3 MPa. Isosteric heats of adsorption at seven excess adsorption amounts and that at zero surface loading were respectively determined by the slopes of the adsorption isosteres and the plot of the temperature dependence of the Henry’s constants. Results show that the limit of the isosteric heat of adsorption at zero surface loading is about and the mean under the experimental condition is about . The values are in the same grade as those of hydrogen on the activated coconut charcoal but smaller than those of hydrogen on the graphitized carbon black P33, the activated carbon AX-21 and the Single-Walled Carbon Nanotubes (SWCNTs). Conclusions are drawn that relatively lower adsorption amounts and the isosteric heat of hydrogen adsorption on the MWCNTs could be ascribed to the small specific surface area and the large mesopores.

Investigation, using density function theory, of coverage of the kaolinite (001) surface during hydrogen adsorption

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 393-402 ◽  
Author(s):  
Jian Zhao ◽  
Wei Gao ◽  
Zhi-Gang Tao ◽  
Hong-Yun Guo ◽  
Man-Chao He
Keyword(s):  
Density Functional ◽  
Hydrogen Adsorption ◽  
Function Theory ◽  
Lattice Relaxation ◽  
Electronic Density ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Coverage Dependence ◽  
Hydrogen Molecules ◽  
Wide Range

ABSTRACTKaolinite can be used for many applications, including the underground storage of gases. Density functional theory was employed to investigate the adsorption of hydrogen molecules on the kaolinite (001) surface. The coverage dependence of the adsorption sites and energetics was studied systematically for a wide range of coverage, Θ (from 1/16 to 1 monolayer). The three-fold hollow site is the most stable, followed by the bridge, top-z and top sites. The adsorption energy of H2 decreased with increasing coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighbouring H2 molecules. The coverage has obvious effects on hydrogen adsorption. Other properties of the H2/kaolinite (001) system, including the lattice relaxation and changes of electronic density of states, were also studied and are discussed in detail.

Intriguing differences in hydrogen adsorption in CPO-27 materials induced by metal substitution

2015 ◽  
Vol 3 (9) ◽  
pp. 4827-4839 ◽  
Author(s):  
Mali H. Rosnes ◽  
Martin Opitz ◽  
Matthias Frontzek ◽  
Wiebke Lohstroh ◽  
Jan Peter Embs ◽  
...  
Keyword(s):  
Comparative Study ◽  
Gas Adsorption ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Hydrogen Gas ◽  
The Other ◽  
Metal Substitution ◽  
Isosteric Heat Of Adsorption ◽  
Open Metal Sites

We present a comparative study of hydrogen gas adsorption experiments on CPO-27–Cu and –Mn. The initial isosteric heat of adsorption in CPO-27–Cu is low for a material containing open metal sites and in contrast to the other members of the CPO-27 series, including the Mn compound.

Hydrogen Storage using Carbon Materials at Room Temperature

2003 ◽  
Vol 801 ◽  
Author(s):  
H. Kajiura ◽  
S. Tsutsui ◽  
K. Kadono ◽  
Y. Murakami ◽  
M. Kakuta ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Room Temperature ◽  
Carbon Materials ◽  
Hydrogen Adsorption ◽  
Constant Pressure ◽  
Graphite Powder ◽  
Milling Process ◽  
Volumetric Method ◽  
Hydrogen Molecules ◽  
Available Carbon

ABSTRACTThe hydrogen adsorption capacity of commercially available carbon materials with different nanostructures was measured at room temperature using an apparatus based on a volumetric method with an error of less than 0.04 wt% per one gram of sample. The obtained results suggest that nanosutures of the sample influence the hydrogen adsorption capacity. To confirm this hypothesis, we prepared nanostructured graphite from graphite powder using a mechanical milling process at a pressure of 2.0 × 10−4 Pa. The untreated graphite adsorbed 0.02wt% of hydrogen at 6 MPa at room temperature, while 0.20 − 0.25 wt% of hydrogen can be repeatedly adsorbed by the nanostructured graphite. Measurements of the hydrogen adsorption rate at constant pressure and pore-size distribution imply that the hydrogen molecules are adsorbed through a diffusion process in pores with a diameter less than 1 nm.

Hydrogen Adsorption in MOF-74 Studied by Inelastic Neutron Scattering

2007 ◽  
Vol 1041 ◽  
Author(s):  
Yun Liu ◽  
Craig M. Brown ◽  
Dan A. Neumann ◽  
Houria Kabbour ◽  
Channing C. Ahn
Keyword(s):  
Neutron Scattering ◽  
Binding Site ◽  
Binding Sites ◽  
Hydrogen Adsorption ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Attractive Potential ◽  
Potential Wells ◽  
Adsorption Sites ◽  
Hydrogen Molecules

AbstractAdsorption of hydrogen and the occupancy of different binding sites as a function of hydrogen loading in MOF-74 are studied using inelastic neutron scattering (INS). Hydrogen molecules are observed to fully occupy the strongest binding site before populating other adsorption sites. The comparison of the INS spectra at 4 K and 60 K indicates that hydrogen adsorbed at the strongest binding site is strongly bound and localized. We also show that when two hydrogen molecules are adsorbed into a single, attractive potential well, the shortest inter-H2 distance is about 3 Å, consistent with our previous observation of inter-H2 distance when adsorbed in two neighboring potential wells.

Ti-coated BC2N nanotubes as hydrogen storage materials

2013 ◽  
Vol 91 (7) ◽  
pp. 598-604 ◽  
Author(s):  
Seifollah Jalili ◽  
Farzad Molani ◽  
Jeremy Schofield
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Molecular Form ◽  
Hydrogen Storage Materials ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Bc2n Nanotubes

Density functional theory (DFT) calculations have been performed to investigate Ti adsorption on BC2N nanotubes and the hydrogen adsorption capacity of Ti-coated structures. Different adsorption sites have been examined for the Ti adatom, and it is found that the most stable structure has a configuration with alternating columns of carbon and boron–nitrogen hexagons. The DFT calculations indicate that an adsorbed Ti atom on a carbon hexagon can bind four hydrogen molecules in molecular form, while Ti atoms on boron–nitride hexagons can adsorb three hydrogen molecules and two hydrogen atoms. Based on the calculations, the gravimetric efficiency corresponding to decoration of 67% of six carbon rings with Ti adatoms is estimated to be 8 wt %. Computation of the charge transfer reveals that the Ti atom on BC2N is in a cationic state. In addition, Ti adsorption has a significant influence on the electronic structure of the nanotubes and allows for the conversion of nanotubes from semiconductors in the pristine state to conductors upon doping. The interactions between the nanotubes, the Ti atom and hydrogen molecules have also been analyzed using Dewar coordination and Kubas interactions.

scholarly journals Contribution of Ash Content Related to Methane Adsorption Behaviors of Bituminous Coals

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yanyan Feng ◽  
Wen Yang ◽  
Wei Chu
Keyword(s):  
Adsorption Capacity ◽  
Coalbed Methane ◽  
Textural Properties ◽  
Isosteric Heat ◽  
Micropore Volume ◽  
Ash Content ◽  
Heat Of Adsorption ◽  
Methane Adsorption ◽  
Adsorbed Phase ◽  
Adsorption Processes

Methane adsorption isotherms on coals with varying ash contents were investigated. The textural properties were characterized by N2adsorption/desorption isotherm at 77 K, and methane adsorption characteristics were measured at pressures up to 4.0 MPa at 298 K, 313 K, and 328 K, respectively. The Dubinin-Astakhov model and the Polanyi potential theory were employed to fit the experimental data. As a result, ash content correlated strongly to methane adsorption capacity. Over the ash range studied, 9.35% to 21.24%, the average increase in methane adsorption capacity was 0.021 mmol/g for each 1.0% rise in ash content. With the increasing ash content range of 21.24%~43.47%, a reduction in the maximum adsorption capacities of coals was observed. In addition, there was a positive correlation between the saturated adsorption capacity and the specific surface area and micropore volume of samples. Further, this study presented the heat of adsorption, the isosteric heat of adsorption, and the adsorbed phase specific heat capacity for methane adsorption on various coals. Employing the proposed thermodynamic approaches, the thermodynamic maps of the adsorption processes of coalbed methane were conducive to the understanding of the coal and gas simultaneous extraction.

ENHANCEMENT EFFECT OF LITHIUM-DOPING FUNCTIONALIZATION ON HYDROGEN ADSORPTION IN METAL-ORGANIC FRAMEWORK

2016 ◽  
Vol 24 (05) ◽  
pp. 1750067 ◽  
Author(s):  
LIANGZHI XIA ◽  
QING LIU ◽  
FENGLING WANG ◽  
YUPENG LI
Keyword(s):  
Hydrogen Adsorption ◽  
Metal Organic Framework ◽  
Enhancement Effect ◽  
Li Doping ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Metal Organic ◽  
Gravimetric Adsorption ◽  
Hydrogen Storage Performance ◽  
Grand Canonical

Grand canonical Monte-Carlo simulation was carried out to study the effect of linker functionalization by Li atoms. In this work, two new Li-doping structures, MOF-808-Li and MOF-808-OLi were theoretically constructed by physical modification and chemical modification, respectively. The results show that both these methods can improve the hydrogen storage performance significantly, owing to the Li atoms increasing the interaction energy between the hydrogen molecules and the Li-doped MOF-808. Furthermore, MOF-808-OLi shows higher hydrogen capacity in comparison to the H2 adsorption in the MOF-808-Li, this can be attributed to the new adsorption sites created by oxygen atom. The gravimetric adsorption capacity of MOF-808-OLi can reach 3.17[Formula: see text]wt.% at 77[Formula: see text]K and 1[Formula: see text]bar, which are significantly higher than the hydrogen adsorption in the unmodified MOF-808.

scholarly journals Adsorption Sites of Hydrogen Atom on Pure and Mg-Doped Multi-Walled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
A. A. Al-Ghamdi ◽  
E. Shalaan ◽  
F. S. Al-Hazmi ◽  
Adel S. Faidah ◽  
S. Al-Heniti ◽  
...  
Keyword(s):  
Hydrogen Adsorption ◽  
Md Simulations ◽  
Material System ◽  
Magnesium Atom ◽  
Multiwalled Carbon ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Mg Doped

Hydrogen adsorption sites on pure multiwalled carbon nanotube (MWCNT) and Mg-doped MWCNTs material system have been investigated using molecular dynamics (MD) simulations as well as quantum chemical calculations. Through combining MWCNTs with Mg, the hydrogen adsorption sites energy on this Mg-MWCNTs system is found to be larger than that of the pure MWCNTs. Additionally, it was found that, through Mg-doping, new adsorption sites for hydrogen molecules are created in comparison with undoped nanotubes. It is also found that H atom is preferably adsorbed at every place near magnesium atom.

INVESTIGATION OF HYDROGEN ADSORPTION ON PLATINUM-DECORATED SINGLE-WALLED CARBON NANOTUBE USING MOLECULAR DYNAMICS SIMULATIONS

2009 ◽  
Vol 08 (04n05) ◽  
pp. 425-432 ◽  
Author(s):  
SEIFOLLAH JALILI ◽  
AREZOU JABERI ◽  
MOHAMMAD GHASEM MAHJANI ◽  
MAJID JAFARIAN
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Adsorption Isotherms ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Hydrogen Desorption ◽  
Dynamics Simulation ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Hydrogen Molecules

Hydrogen adsorption isotherms for (8, 0) platinum-decorated single-walled carbon nanotube were studied using molecular dynamics simulation. Adsorption isotherms were obtained for both internal and external surfaces of nanotube at several temperatures from 77 K up to 400 K. The results were compared with the bare nanotube at the same conditions. Adsorption coverage, isosteric heat, binding energy, hydrogen desorption, and readsorption were calculated for both internal and external surfaces of nanotube. At low temperatures, hydrogen molecules were adsorbed significantly, but at higher temperatures, thermal energies reduced this capacity. Under the same conditions, the platinum-decorated single-walled carbon nanotube hydrogen adsorption is significantly higher than the bare one.

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