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1.
Dong Seok Shin Won G. Hong Hyun-Seok Jang Hae Jin Kim Byung Hoon Kim 《International Journal of Hydrogen Energy》2018,43(33):16136-16140
To establish the relation between optimum interlayer distance for hydrogen storage and electrical conductance, we measured the electrical conductance (G) of 3-dimensional graphene oxide (GOA) depending on high H2 pressure, from vacuum to 20 bar. The GOA was synthesized using diaminoalkanes with two lengths of alkyl chains, and the interlayer distance of GOA was modulated by thermal annealing. A decrease in G was observed as the H2 pressure increased. The maximum variation in G was observed at 7.0 Å of interlayer distance. When the interlayer distance-dependent H2 uptake was considered, we confirmed that the maximum variation in G as well as optimum H2 uptake occurred at the same interlayer distance, 7.0 Å. The variation in G due to H2 exposure provides understanding about the behavior of hydrogen molecules on these materials and on the modulation of the electronic structure of the materials. 相似文献
2.
G. Nagaraju J.P. Shubha K. Manjunath J. Dupont 《International Journal of Hydrogen Energy》2018,43(8):4028-4035
Photocatalytic hydrogen generation is one of the most promising solutions to convert light energy into green chemical energy. In the present work, methoxy ethyl methyl imidazolium methyl sulphonate ionic liquid is used for the synthesis of i-TiO2 nanoparticles via ionothermal method at 120 °C. The obtained products were characterized by various spectroscopic techniques like XRD, FTIR, Raman, UV–visible, DRS, TEM and TG-DSC analysis. XRD pattern confirmed the anatase phase with minor rutile phase having average crystallite size of 5 nm. From the FTIR spectrum, the band appeared at ~547 cm?1 confirmed the Ti–O–Ti stretching and also few bands of ionic liquid. UV–vis spectrum clearly reveals the blue shift due to size effect of TiO2. The spherical surface structure and particle size (15–30 nm) have been studied in detail using TEM images. Finally, the practical applicability of the as synthesized i-TiO2 nanoparticles is shown by using it as a photocatalyst towards the generation of H2 through water splitting reaction and it is found to be 462 μmol h?1g?1. 相似文献
3.
The mixed metal oxides NiFe2O4 and CoFe2O4 are candidate materials for the Chemical Looping Hydrogen (CLH) process, which produces pure and separate streams of H2 and CO2 without the use of complicated and expensive separations equipment. In the CLH process, syngas reduces a metal oxide, oxidizing the H2 and CO in the syngas to H2O and CO2, and “stores” the chemical energy of the syngas in the reduced metal oxide. The reduced metal oxide is then oxidized in steam to regenerate the original metal oxide and produce H2. In this study, we report thermodynamic modeling and experimental results regarding the syngas reduction and H2O oxidation of NiFe2O4 and CoFe2O4 to determine the feasibility of their use in the CLH process. Modeling predicts the oxidation of nearly all the CO and H2 in syngas to H2O and CO2 during the reduction step for both materials, and regeneration of the mixed metal spinel phase during oxidation with excess H2O. Laboratory tests in a packed bed reactor confirmed over 99% conversion of H2 and CO to H2O and CO2 during reduction of NiFe2O4 and CoFe2O4. Powder XRD analysis of the reduced materials showed, in accordance with thermodynamic predictions, the presence of a spinel phase and a metallic phase. High reactivity of the reduced NiFe2O4 and CoFe2O4 with H2O was observed, and XRD analysis confirmed re-oxidation to NiFe2O4 and CoFe2O4 under the conditions tested. When compared with a conventional Fe-based CLH material, the mixed metal spinels showed a higher extent of reduction under the same conditions, and produced four times the H2 per mass of active material than the Fe-based material. Analysis of the H2 and CO consumed in the reduction and the H2 produced during the oxidation showed over 90% conversion of the H2 and CO in syngas back to H2 during oxidation. 相似文献
4.
The hydrogen (H2) sensing properties, including the sensor response, response time and recovery time, of different sensor architectures based on tungsten oxide (WO3) were investigated to assess the feasibility of using WO3 in producing practical H2 sensors. Each of the different sensor architectures consists of 3 layers. The first layer is a 2.5-nm palladium (Pd) layer, which is always deposited onto a highly porous WO3 nanocluster layer. The third layer is an Au/Ti electrode layer, which may be constructed in the form of interdigitated electrodes or 5 × 5 mm2 pad electrodes, which is located either on the top surface of the Pd layer or at the bottom of the WO3 film. Furthermore, the WO3 layer was also constructed to be either 11.2 nm or 153 nm thick. The sensor design consisting of a 2.5-nm Pd layer on an 11.2-nm WO3 layer with interdigitated electrodes at the bottom of the layer was found to exhibit the best overall H2 sensing properties, with excellent cyclic stability over 600 cycles of operation. 相似文献
5.
Byung Hoon Kim Yong Ju Yun Won G. Hong Chang Hee KimSang Moon Lee Han Young Yu Hae Jin Kim 《International Journal of Hydrogen Energy》2011,36(20):12887-12891
The high pressure H2 sorption isotherms for vanadium pentoxide foam (VOF) were obtained at a liquid nitrogen temperature. The enhancement of hydrogen storage capacity occurred in as-prepared VOF (∼1.0 wt%) in contrast to that in pristine vanadium pentoxide (∼0.2 wt%). The maximum capacity of hydrogen storage (∼2.0 wt%) was achieved by thermal annealing at Ta = 623 K. The enhancement of hydrogen storage in VOF is attributed to the morphological modulation by thermal annealing. 相似文献
6.
We set up and validated a volumetric method to quantify the amount of hydrogen “delivered” after saturation of a solid material as adsorber at different pressures (up to 100 kgf/cm2) and temperatures (down to 77 K). This is the practically most relevant datum to quantify the effectiveness of an adsorbent for the present application. A complementary dynamic method has been also developed to take into account the reversibility of adsorption and to assess in at least a semi-quantitative way the strength of interaction between H2 and the adsorbent. The method has been applied to compare the hydrogen storage capacity of some significant different carbon-based materials (two active carbons and one graphite), as supplied or after thermal treatments under oxidising or reducing conditions. The best results, ca. 7 wt% H2 “delivered”, were achieved after saturation at 77 K, 20 kgf/cm2 with an active carbon with ca. 3000 m2/g of apparent specific surface area. The thermal treatments, almost always inducing a drop in surface area, showed effective only for saturation at 273 K, in particular the oxidising procedure. This was correlated to the formation of surface oxidised species, likely carboxylic groups, which improved the interaction strength between H2 and the adsorbent. 相似文献
7.
In this work high quality cobalt oxide silica membranes were synthesized on alumina supports using a sol–gel, dip coating method. The membranes were subsequently connected into a steel module using a graphite based proprietary sealing method. The sealed membranes were tested for single gas permeance of He, H2, N2 and CO2 at temperatures up to 600 °C and feed pressures up to 600 kPa. Pressure tests confirmed that the sealing system was effective as no gas leaks were observed during testing. A H2 permeance of 1.9 × 10−7 mol m−2 s−1 Pa−1 was measured in conjunction with a H2/CO2 permselectivity of more than 1500, suggesting that the membranes had a very narrow pore size distribution and an average pore diameter of approximately 3 Å. The high temperature testing demonstrated that the incorporation of cobalt oxide into the silica matrix produced a structure with a higher thermal stability, able to resist thermally induced densification up to at least 600 °C. Furthermore, the membranes were tested for H2/CO2 binary feed mixtures between 400 and 600 °C. At these conditions, the reverse of the water gas shift reaction occurred, inadvertently generating CO and water which increased as a function of CO2 feed concentration. The purity of H2 in the permeate stream significantly decreased for CO2 feed concentrations in excess of 50 vol%. However, the gas mixtures (H2, CO2, CO and water) had a more profound effect on the H2 permeate flow rates which significantly decreased, almost exponentially as the CO2 feed concentration increased. 相似文献
8.
Cluster-based materials are candidate materials for solid-state hydrogen storage owing to their special geometric and electronic structures. The surface adsorption and the encapsulated storage of H2 molecules in a cagelike (MgO)12 cluster have been studied using density functional theory (DFT) calculations including a dispersion interaction. The results revealed that the cagelike (MgO)12 cluster surface can adsorb 24 H2 molecules with an average adsorption energy of 0.116 eV/H2, which brings about a gravimetric density of 9.1 wt%. Compared with dispersion-corrected DFT calculations, the traditional DFT method substantially underestimates the surface adsorption strength. According to symmetric configurations, a maximum capacity of six H2 molecules can be stored in the interior space of the cagelike (MgO)12 cluster. The encapsulated H2 molecules are trapped by stepwise energy barriers of 0.433–2.550 eV, although the storage is an endothermic process. The present study will be beneficial for hydrogen storage in cagelike clusters and assembled porous materials. 相似文献
9.
A. Iriondo J.F. Cambra M.B. Güemez V.L. Barrio J. Requies M.C. Sánchez-Sánchez R.M. Navarro 《International Journal of Hydrogen Energy》2012
In this work, ZrO2 was employed as support and as Al2O3 modifier of Ni based catalysts due to its special interesting characteristics. The catalytic activity of these systems was studied in steam reforming of glycerol to produce H2. As the activity results at 773 K and 873 K showed, the NiZ catalyst allowed low glycerol conversion and H2 production when compared to the NiγA catalyst. Moreover, the NiZ catalyst was not able to reform intermediate liquid products into gaseous products. 相似文献
10.
This study investigated the effect of gases such as CO2, N2, H2O on hydrogen permeation through a Pd-based membrane −0.012 m2 – in a bench-scale reactor. Different mixtures were chosen of H2/CO2, H2/N2/CO2 and H2/H2O/CO2 at temperatures of 593–723 K and a hydrogen partial pressure of 150 kPa. Operating conditions were determined to minimize H2 loss due to the reverse water gas shift (RWGS) reaction. It was found that the feed flow rate had an important effect on hydrogen recovery (HR). Furthermore, an identification of the inhibition factors to permeability was determined. Additionally, under the selected conditions, the maximum hydrogen permeation was determined in pure H2 and the H2/CO2 mixtures. The best operating conditions to separate hydrogen from the mixtures were identified. 相似文献
11.
Kiran Raj G. Burra Ghada Bassioni Ashwani K. Gupta 《International Journal of Hydrogen Energy》2018,43(51):22852-22860
Hydrogen sulfide (H2S) gas is a by-product from natural gas refining, hydrodesulfurization of various fossil fuels, and syngas cleaning from pyrolysis and gasification. Catalytic pyrolysis of H2S provides an alternative and effective pathway to recover both H2 and sulfur. Catalysts from hydrotalcite of ZnAl, ZnNiAl, and ZnFeAl were employed for H2S pyrolysis and compared with TiO2 and MoS2 at atmospheric pressure and temperatures in the range of 923–1123 K. Kinetic analysis was carried out in a packed bed reactor which revealed the effect of H2S partial pressures to be of the order of 0.8–1 with respect to H2S. The developed novel catalysts showed improved performance with significantly reduced activation energy compared to TiO2 by 30 kJ/mol as well as higher H2S conversion during pyrolysis (17% at 1173 K) than with MoS2 catalyst, even at high H2S partial pressure which is necessary for viable hydrogen production. The new approach showed an alternate economical and efficient pathway of catalyst design to obtain high activity and stability for simultaneous H2 energy and pure sulfur recovery from unwanted H2S resources. 相似文献
12.
Yong Pan 《International Journal of Hydrogen Energy》2018,43(6):3087-3091
Hydrogen storage mechanism and hydrogen storage capacity are the great challenges for the development of hydrogen energy technology. Besides the better catalytic properties, it is crucial to search for suitable material that provides enough space to store H2 molecule. Similar to graphene, MoS2 with S-S layered structure opens up a new way to improve the hydrogen storage capacity. By using the first-principles calculations, in this work, we investigate the hydrogen diffusion mechanism, hydrogenation process and hydrogen storage capacity of MoS2 with S-S interlayer. We find that hydrogen prefers to diffuse into S-S interlayer along the interstitial site (path: IT-IT). H2 molecule is a stable in S-S interlayer because the charge interaction of H-H atoms is stronger than that of H-S atoms. Finally, we predict that MoS2 with S-S layered-by-layered stacking can effectively improve the hydrogen storage capacity. 相似文献
13.
The hydrogenation and dehydrogenation behaviours of the YNi3.5Al0.5Mg compound were studied by in situ X-ray diffraction under hydrogen pressure and at room temperature. The changes of (i) the lattice parameters, (ii) the crystallite size and (iii) the lattice strain during the sorption process (i.e. along the PC isotherms) were studied. These results indicate that the crystallite size decreases by a factor of 2. The micro deformations increase at first and then tend to almost zero at the end of the sorption cycle. This behaviour is explained in terms of co-existence of the metal (i.e. α phase) and metal hydride (i.e. β phase) phases. The change in crystallinity is consistent with the hydrogen induced amorphisation process existing in a lot of AB2 compounds. No anisotropic effects can be highlighted on this pseudo-AB2 compounds in contrary with what could be observed in AB5 compounds. 相似文献
14.
Hydrogen absorption and desorption properties in nanocrystalline LaMg2Ni are presented. Nanostructured phases have been obtained by milling grain coarse ingot and by mechanically alloying the parent elements. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis and thermal desorption measurements. Ball milling and mechanical alloying give a significant refinement of the microstructure. Reactive milling has been used for hydrogen absorption experiments. Hydrogenation by means of reactive milling at 300 K under a pressure of 0.4 MPa leads to the formation of a stable La-hydride phase together with an amorphous phase. Thermal desorption up to 983 K of hydrogenated samples leads again to parent LaMg2Ni phase. 相似文献
15.
Zhi Yang Donghong Wang Li-Chun Xu Xuguang Liu Xiuyan Li Bingshe Xu 《International Journal of Hydrogen Energy》2014
Based on density functional theory, the capacities of FeC5H5, Fe2C5H5 and one-dimensional (FeC5H5)∞ nanowire as hydrogen storage media were investigated. The results show that FeC5H5 and Fe2C5H5 can adsorb five and ten H2 molecules, respectively, and form stable FeC5H5(H2)5 and Fe2C5H5(H2)10 systems. The hydrogen storage capacities of the two systems are 7.63 wt% and 10.15 wt%, while the average adsorption energies are 0.49 and 0.73 eV/H2, indicating that FeC5H5 and Fe2C5H5 are excellent hydrogen storage media. In addition, (FeC5H5)∞ nanowire can also adsorb H2 molecules (1.62 wt%). Most importantly, the magnetic and electrical properties of the nanowire are sensitive to the additional H2, thus (FeC5H5)∞ can be used for selecting and detecting H2 molecules. 相似文献
16.
Prior investigations have proposed, and successfully implemented, a stand-alone supply of aqueous hydrogen peroxide for use in fuel cells. An apparent obstacle for considering the use of aqueous hydrogen peroxide as an energy storage compound is the corrosive nature of the nominally required 50 wt.% maximum concentration. Here we propose storage of concentrated hydrogen peroxide in a high weight percent solid slurry, namely the equilibrium system of CaO2·2H2O2(s)/H2O2(aq), that mitigates much of the risk associated with the storage of such high concentrations. We have prepared and studied surrogate slurries of calcium hydroxide/water that are assumed to resemble the peroxo compound slurries. These slurries have the consistency of a paste rather than a distinct two-phase (liquid plus solid) system. This paste-like property of the prepared surrogates enable them to be contained within a 200 lines-per-inch. (LPI) nickel mesh screen (33.6% open area) with no solids leakage, and only liquid transport driven by an adsorbent material is placed in physical contact on the exterior of the screen. This hydrogen peroxide slurry approach suggests a convenient and safe mechanism of storing hydrogen peroxide for use in, say, vehicle applications. This is because fuel cell design requires only aqueous hydrogen peroxide use, that can be achieved using the separation approach utilizing the screen material here. This proposed method of storage should mitigate hazards associated with unintentional spills and leakage issues arising from aqueous solution use. 相似文献
17.
The adsorption of hydrogen on single-walled and multi-walled carbon nanotubes (CNTs) was investigated at 77 and 298 K, in the pressure range of 0–1000 Torr. The adsorption isotherms indicate that adsorption follows the Langmuir model. Hydrogen uptakes were found to depend strongly on the nature of the CNTs. Single-walled CNTs adsorb significantly higher quantities of hydrogen per unit mass of the solid, while the opposite is true on a per unit surface area basis. This observation implies that adsorption takes place selectively on specific sites on the surface. The hydrogen uptake capacity of CNTs was also found to be affected by the purity of the materials, increasing with increasing purity. Temperature programmed desorption indicated that relatively strong adsorption bonds develop between adsorbent and adsorbate and that a single type of adsorption site exists on the solid surface. 相似文献
18.
Shin-ichi Yamazaki Kentaro Kuratani Hiroshi Senoh Zyun Siroma Kazuaki Yasuda 《Journal of power sources》2010,195(4):1-147
A one-compartment membrane-less electrochemical H2 generator from borohydride was realized using a Rh porphyrin and RuO2 as the anode and cathode, respectively. H2 generation from this cell was successfully controlled electrochemically by varying the potential applied. The regulation of H2 generation was based on the selectivity of the anode and cathode. We found that RuO2 exhibits H2O electro-reduction activity without electro-oxidation or chemical decomposition of borohydride, and used the catalyst as a selective cathode in the electrochemical H2 generator. Anode and cathode potentials of the electrochemical H2 generator were measured separately. The both potentials were discussed in terms of the catalytic activities of a Rh porphyrin and RuO2. 相似文献
19.
N.A. Sazelee N.H. Idris M.F. Md Din N.S. Mustafa N.A. Ali M.S. Yahya F.A. Halim Yap N.N. Sulaiman M. Ismail 《International Journal of Hydrogen Energy》2018,43(45):20853-20860
Previous studies have shown that ferrites give a positive effect in improving the hydrogen sorption properties of magnesium hydride (MgH2). In this study, another ferrite, i.e., BaFe12O19, has been successfully synthesised via the solid state method, and it was milled with MgH2 to enhance the sorption kinetics. The result showed that the MgH2 + 10 wt% BaFe12O19 sample started to release hydrogen at about 270 °C which is about 70 °C lower than the as-milled MgH2. The doped sample was able to absorb hydrogen for 4.3 wt% in 10 min at 150 °C, while as-milled MgH2 only absorbed 3.5 wt% of hydrogen under similar conditions. The desorption kinetic results showed that the doped sample released about 3.5 wt% of hydrogen in 15 min at 320 °C, while the as-milled MgH2 only released about 1.5 wt% of hydrogen. From the Kissinger plot, the apparent activation energy of the BaFe12O19-doped MgH2 sample was 115 kJ/mol which was lower than the milled MgH2 (141 kJ/mol). Further analyses demonstrated that MgO, Fe and Ba or Ba-containing contribute to the improvement by serving as active species, thus enhancing the MgH2 for hydrogen storage. 相似文献
20.
Yunhu Li Dianxue CaoYao Liu Ran LiuFan Yang Jinling YinGuiling Wang 《International Journal of Hydrogen Energy》2012
The growth of CuO nanosheet arrays on Cu foil was demonstrated. The morphology and structure of the CuO were examined by scanning electron microscopy and X-ray diffraction spectroscopy. The catalytic performance of the obtained CuO/Cu electrode for hydrogen peroxide electroreduction in 3.0 mol dm−3 KOH was evaluated by means of cyclic voltammetry and chronoamperometry. The CuO/Cu electrode shows an onset potential for H2O2 electroreduction comparable to Co3O4 nanowire arrays grown on Ni foam and around 100 mV more negative than precious metal catalysts, such as Pt and Pd, demonstrating its good catalytic activity for H2O2 electroreduction. The stabilized mass current density for H2O2 electroreduction on the CuO/Cu electrode at −0.3 V reached about 57% of that on Co3O4 nanowire arrays grown on nickel foam. Compared to conventional fuel cell electrodes fabricated by mixing active materials with conducting agents and polymer binders, this electrode of CuO nanosheet arrays directly grown on Cu has superior mass transport property, which combining with its low-cost and facile preparation, make it a promising electrode for fuel cell using H2O2 as the oxidant. 相似文献