Amount Of Hydrogen Uptake Research Articles

Optimizing parameters affecting synthetize of CuBTC using response surface methodology and development of AC@CuBTC composite for enhanced hydrogen uptake

CuBTC, a widely studied metal-organic framework, is a promising candidate for industrial applications owing to its easy synthesis procedure and excellent textural properties. In this research CuBTC was synthesized by solvothermal method with the purpose of hydrogen uptake. Response surface methodology (RSM) was employed in order to determine the optimum synthesis condition with the highest hydrogen capacity. Amount of ligand, volume of solvent, synthesis temperature, and synthesis time were chosen as independent variables, while the amount of hydrogen uptake was selected as the response. Subsequently, activated carbon (AC) was incorporated within the optimized CuBTC structure as a “void space filling agent” and adsorption behavior of AC@MOF composite was evaluated from the view point of different AC contents. It was observed that the hydrogen uptake of AC@CuBTC composite was increased compared to bare CuBTC samples. This finding could be attributed to effective utilization of micropore volume of CuBTC structure by AC incorporation.

Hydrogen adsorption on single walled carbon nanotubes-tungsten trioxide composite

In this work, hydrogen storage property of single walled carbon nanotubes-tungsten trioxide (SWCNTs-WO3) composite is investigated. The composite is prepared and hydrogenated by electron beam (e-beam) evaporation technique. Hydrogenation is carried out during the preparation of the composite itself. The amount of hydrogen uptake by the composite is 2.7 wt%, which is due to the collective adsorption of hydrogen by CNTs and WO3 nanostructured materials, the method of preparation and hydrogenation involved. The incorporated hydrogen is completely (100%) released in the temperature range of 175–305 °C which in turn infers that the hydrogenated composite is stable at room temperature. The stored hydrogen has the average binding energy of 0.4 eV and the nature of binding is found to be weak chemisorption. Spillover mechanism is attributed for the hydrogen uptake of the composite.

Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG) Over Nickel-Phosphorus-Alumina Xerogel Catalyst Prepared by a Carbon-Templating Epoxide-Driven Sol-Gel Method.

A nickel-phosphorus-alumina xerogel catalyst was prepared by a carbon-templating epoxide-driven sol-gel method (denoted as CNPA catalyst), and it was applied to the hydrogen production by steam reforming of liquefied natural gas (LNG). For comparison, a nickel-phosphorus-alumina xerogel catalyst was also prepared by a similar method in the absence of carbon template (denoted as NPA catalyst). The effect of carbon template addition on the physicochemical properties and catalytic activities of the catalysts in the steam reforming of LNG was investigated. Both CNPA and NPA catalysts showed excellent textural properties with well-developed mesoporous structure. However, CNPA catalyst retained a more reducible nickel aluminate phase than NPA catalyst. XRD analysis of the reduced CNPA and NPA catalysts revealed that nickel sintering on the CNPA catalyst was suppressed compared to that on the NPA catalyst. From H2-TPD and CH4-TPD measurements of the reduced CNPA and NPA catalysts, it was also revealed that CNPA catalyst with large amount of hydrogen uptake and strong hydrogen-binding sites showed larger amount of methane adsorption than NPA catalyst. In the hydrogen production by steam reforming of LNG, CNPA catalyst with large methane adsorption capacity showed a better catalytic activity than NPA catalyst.

Hydrogen storage in a series of Zn-based MOFs studied by Sanchez–Lacombe equation of state

One of the most famous porous adsorbents used for separation and storage of hydrogen is metal organic framework (MOF). In this study, the experimental data related to hydrogen adsorption on and desorption from five adsorbents including MOF-5, MOF-177, MOF-200, MOF-205 and MOF-210 is adopted. Then, the hydrogen sorption is modeled by applying Sanchez–Lacombe Equation of State (SL EoS). The amount of hydrogen uptake in the adsorbents is obtained through hydrogen-adsorbents phase equilibrium calculations at temperature 77 K and various pressures up to 80 × 105 Pa. The result is compared with the experimental data to show the precision of SL equation of state in predicting the hydrogen sorption trend. SL EoS predicts the experimental results satisfactorily, even though in comparison with PHSC EoS, the latter shows a little reduction in average absolute deviation.

Hydrogen storage in a series of Zn-based IRMOFs studied by Sanchez–Lacombe equation of state

In this work, the adsorptive behaviors of molecular hydrogen in 10 different isoreticular metal-organic frameworks, namely, IRMOF-1, -2, -3, -6, -8, -10, -11, -13, -18 and -20 have been studied using Sanchez–Lacombe equation of state. Sanchez–Lacombe equation of state has three characteristic parameters: characteristic density, characteristic pressure, and characteristic temperature which have been calculated from group contribution procedure. The amount of hydrogen uptake in IRMOFs has been obtained through gas-adsorbents phase equilibrium calculations at temperature 77 K and various pressures up to 80 × 105 Pa. Finally, the results have been compared with the experimental data to show the precision of SL equation of state in predicting the hydrogen sorption data.

Hydrogen storage in a series of Zn-based MOFs studied by PHSC equation of state

One of the most famous porous adsorbents used for separation and storage of several gases is metal organic framework (MOF). In this study, the experimental data related to hydrogen adsorption on and desorption from five adsorbents including MOF-5, MOF-177, MOF-200, MOF-205 and MOF-210 is adopted. Then, the hydrogen sorption is modeled by applying Perturbed Hard Sphere Chain Equation of State (PHSC EoS). PHSC equation of state has three molecular-based parameters, namely, the number of segments per molecule, the hard-sphere diameter and the non-bonded interaction energy, respectively. The amount of hydrogen uptake in the adsorbents is obtained through gas-adsorbents phase equilibrium calculations at temperature 77 K and various pressures up to 80 × 105 Pa. Finally, the result is compared with the experimental data to show the precision of PHSC equation of state in predicting the hydrogen sorption trend.

The effect of alloying modifications on hydrogen uptake of zirconium-alloy welding specimens during corrosion tests

The hydrogen uptake behavior during corrosion tests for electron beam welding specimens made out of Zircaloy-4 and zirconium alloys with different compositions was investigated. Results showed that the hydrogen uptake in the specimens after corrosion tests increased with increasing Cr content in the molten zone. This indicated that Cr element significantly affected the hydrogen uptake behavior. Fe and Cr have a low solubility in α-Zr and exist mainly in the form of Zr(Fe,Cr) 2 precipitates, which is extremely reactive with hydrogen in its metallic state. It is concluded that the presence of Zr(Fe,Cr) 2 second phase particles (SPPs) is responsible for the increase in the amount of hydrogen uptake in the molten zone of the welding samples after corrosion, as Zr(Fe,Cr) 2 SPPs embedded in α-Zr matrix and exposed at the metal/oxide interface could act as a preferred path for hydrogen uptake.

Synthesis and evaluation on performance of hydrogen storage of multi-walled carbon nanotubes decorated with platinum

By means of chemical reduction, nanoparticles of platinum were deposited on the surface of multi-walled carbon nanotubes (MWCNTs). The performance of hydrogen storage of as-prepared MWCNTs decorated with platinum was investigated. The results indicate that: (1) Hydrogen uptake is more quick and intense for decorated MWCNTs than that for not decorated ones at 10.931 MPa and room temperature. The saturation of hydrogen uptake of the former only lasts about 30 min, while the latter needs about 150 min; (2) The amount of hydrogen uptake of decorated MWCNTs is about 1.13wt%, which is larger than that of not decorated ones (about 0.54wt%); (3) However, more than 37% hydrogen absorbed by decorated MWCNTs is chemisorbed.

Hydrogen Storage in Titanium-Magnesium-Nickel Mixtures

ABSTRACTThe hydrogen interaction properties of mechanically alloyed mixtures of Ti, Mg, and Ni have been shown to be strongly dependent on the time and energy of ball milling. Mixtures ball milled at a ball to powder ratio (by mass) of 20:1 were able to absorb 3–4 wt% hydrogen. Mixtures ball milled at a ball to powder ratio of 70:1 were able to absorb up to 11 wt% hydrogen. The dependence of hydrogen uptake on ball milling time and energy is shown to be related to the microstructural morphology of the ball milled powders. The original Mg powder particles were heavily deformed by the ball milling process and contained nano-sized inclusions of both Ti and Ni at the surface. The higher energy ball milled samples showed a more refined microstructure and a greater hydrogen capacity. In addition, there was an inverse relationship between the amount of hydrogen uptake and the size of inclusions at the surface of the particles.

The effect of novel processing on hydrogen uptake in FeTi- and magnesium-based alloys

This paper discusses the production and initial evaluation of hydrogen storage alloys produced by physical vapour deposition (PVD) and mechanical alloying (MA). PVD is usually associated with the production of thin films and coatings. However, DERA Farnborough have developed a high rate vapour condensation process to produce bulk deposits, in some cases up to 44 mm thick. Vapour condensation using electron beam evaporation produces the ultimate in cooling rates with extended solid solubility and refinement of microstructure, which produce enhanced physical and mechanical properties. MA is a complimentary technique for processing hydrogen storage materials which has been developed within DERA over the past 3 years. These techniques have been applied to Mg and FeTi alloy systems and it is shown that both methods greatly enhance the amount of hydrogen uptake and the ease of activation.

Buchbesprechung

CuBTC, a widely studied metal-organic framework, is a promising candidate for industrial applications owing to its easy synthesis procedure and excellent textural properties. In this research CuBTC was synthesized by solvothermal method with the purpose of hydrogen uptake. Response surface methodology (RSM) was employed in order to determine the optimum synthesis condition with the highest hydrogen capacity. Amount of ligand, volume of solvent, synthesis temperature, and synthesis time were chosen as independent variables, while the amount of hydrogen uptake was selected as the response. Subsequently, activated carbon (AC) was incorporated within the optimized CuBTC structure as a “void space filling agent” and adsorption behavior of [email protected] composite was evaluated from the view point of different AC contents. It was observed that the hydrogen uptake of [email protected] composite was increased compared to bare CuBTC samples. This finding could be attributed to effective utilization of micropore volume of CuBTC structure by AC incorporation.

Hydriding behavior in Ca/1bMg/1bNi/1bB

Hydriding behavior (thermodynamic, kinetic and structural data) of selected materials in Ca/1bMg/1bNi/1bB is reported. A number of new hydrides is established including CaNi 2H 3.4, CaNi 3H 4.6 and CaNi 4BH 3.8. Mg substitutes for Ca in CaNi 2 within a broad homogeneous range. This leads to a reduction in the rate as well as amount of hydrogen uptake. The reduction in the hydriding rate yields crystallographically better defined hydride phases. Most hydrides based on Ca react violently with water yielding fine particles of Ni, H 2 and Ca(OH) 2. CaNi 5H 6 is found to show decomposition reactions both in the hydriding process as well as on storage over extended periods of time (of order a year).

Magnetic properties of hydrides of YMn 2−xFe x

Hydrides of YMn 2- x Fe x and related materials show a characteristic shift in the ordering temperatures when compared with the parent materials. This is in line with a predictive scheme based on a rigid band approach. The degree of amorphicity and amount of hydrogen uptake have pronounced effects on magnetic properties.

Steam Reforming of Hydrocarbons on Noble Metal Catalysts (Part 2)

Steam-reforming of n-heptane on rhodium catalysts was investigated under atmospheric pressure and in the temperature range from 550 to 800°C. The degree of dispersion of supported rhodium was determined from hydrogen chemisorption data measured at 25°C by a pulse technique.Rhodium supported on silica was found to sinter considerably on reduction in hydrogen flow, and its activity also decreased. On the other hand, γ-alumina support was found to keep the dispersion of rhodium unchanged on reduction in the temperature range from 550 to 800°C.The activity per weight of a catalyst increased with the concentration of rhodium supported on γ-alumina. The activity was correlated with the amount of hydrogen uptake when more than 0.2% of rhodium was supported.The product composition from reactions at 600°C was compared with the equilibrium composition determined by the following two reactions: i) CH4+H2O=CO+3H2, and ii) CO+H2O=CO2+H2. The composition was found to deviate considerably from the equilibrium at earlier stages of the reaction, but to approach it with increasing conversion of n-heptane. It was suggested that the rate of these equilibrating reactions, especially of the reaction ii), was smaller than that of the initial decomposition of the feed hydrocarbon.