共查询到20条相似文献,搜索用时 15 毫秒
1.
Mei-qiang Fan Shu Liu Li-Xian Sun Fen Xu Shuang Wang Jian Zhang De-sheng Mei Fen-lei Huang Qing-ming Zhang 《International Journal of Hydrogen Energy》2012
Solid-state AlLi/NaBH4 mixture activated by CoCl2 salt is fabricated for hydrogen generation via a milling process, providing uniform dispersion of AlLi alloy and CoCl2 salt among pulverized NaBH4 particles in order to improve NaBH4 hydrolysis through the contact of NaBH4 with active catalytic sites. The active catalytic sites come from Co2B loaded in Al(OH)3 (Bayerite) or LiAl2(OH)7 hydrate, generated from the reaction of CoCl2, AlLi alloy, and NaBH4 in water. The results show that the gravimetric hydrogen storage capacity is as high as 6.4 wt.% and an efficiency of above 90% in 30-min hydrolysis at 323 K could be achieved using the limited amount of water. The hydrogen generation amount and rate could be regulated by changing the composition, mixing style, mixture/water weight ratio, and hydrolysis temperature. The relative mechanism is explored. 相似文献
2.
3.
Mei-qiang Fan Shu LiuWen-qiang Sun Yong FeiHua Pan Chun-Ju LvDa Chen Kang-Ying Shu 《International Journal of Hydrogen Energy》2011,36(24):15673-15680
On-demand hydrogen generation from solid-state Al/NaBH4 hydrolysis activated by Li-NiCl2 additives are elaborated in the present paper. Hydrogen generation amount and rate can be regulated by changing Al/NaBH4 weight ratio, Li and NiCl2 amount, hydrolytic temperature, etc. The optimized Al−10 wt.% Li−15 wt.% NiCl2/NaBH4 mixture (weight ratio of 1:1) yields 1778 ml hydrogen/1 g mixture with 100% efficiency within 50 min at 323 K. The improved hydrolytic performance comes from the effect of Li-NiCl2 additives, which decrease aluminum particle size in the milling process and produce the catalytic promoter BNi2/Al(OH)3 in the hydrolytic process. Compared with the conventional reaction of Al and NaBH4 in water, there is an interaction of Al/NaBH4 hydrolysis which improves the hydrolytic kinetics of Al/NaBH4 via the catalytic effect of hydrolysis by-products Al(OH)3, BNi2, and NaBO2. The Al/NaBH4 mixture may be applied as a portable hydrogen generation material. Our experimental data lay a foundation for designing practical hydrogen generators. 相似文献
4.
Xiaofeng Wang Shaorui Sun Zili Huang Haijun Zhang Shaowei Zhang 《International Journal of Hydrogen Energy》2014
Poly(N-vinyl-2-pyrrolidone)(PVP)-protected Au/Ni bimetallic nanoparticles (BNPs) were prepared in one-vessel via chemical reduction of the corresponding ions with dropwise addition of NaBH4, and their catalytic activity in the hydrogen generation from hydrolysis of a basic NaBH4 solution was examined. The structure, particle size, and chemical composition of the resultant BNPs were characterized by Ultraviolet–visible spectrophotometry (UV–Vis), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM) and High-resolution transmission electron microscopy (HR-TEM). The effects of processing parameters such as metal composition, metal ion concentration, and mole ratio of PVP to metal ion on the hydrolysis of a basic NaBH4 solution were studied in detail. The results indicated that as-prepared Au/Ni BNPs showed a higher catalytic activity than corresponding monometallic NPs (MNPs) in the hydrogen generation from the hydrolysis reaction of a basic NaBH4 solution. Among all the MNPs and BNPs, Au/Ni BNPs with the atomic ratio of 50/50 exhibited the highest catalytic activity, showing a hydrogen generation rate as high as 2597 mL-H2 min−1 g-catalyst−1 at 30 °C, which can be ascribed to the presence of negatively charged Au atoms and positively charged Ni atoms. Based on the kinetic study of the hydrogen generation from the hydrolysis reaction of a basic NaBH4 solution over the PVP-protected Au/Ni BNPs, the corresponding apparent activation energy was determined as 30.3 kJ/mol for the BNPs with the atomic ratio of 50/50. 相似文献
5.
In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH4 gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH4 concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl2 catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH4 gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH4 solution. The NaBH4 gel also successfully powered a NaBH4-air battery. 相似文献
6.
Guiling Wang Xunying Wang Rongrong Miao Dianxue Cao Kening Sun 《International Journal of Hydrogen Energy》2010
Activation of the MmNi4.03Co0.42Mn0.31Al0.24 hydrogen storage alloy electrode is performed by immersing the electrode in a solution containing 6.0 mol dm−3 NaOH and 0.1 mol dm−3 NaBH4. The effects of activation on the electrocatalytic activity of the electrode for NaBH4 oxidation are investigated by cyclic voltammetry and chronoamperometry. Immersion activation greatly improves the electrocatalytic activity of the alloy electrode. Hydrogen was absorbed in the alloy during the immersion activation treatment and its electrooxidation is responsible for the high initial oxidation current. The stabilized current mainly results from the direct oxidation starting from the borohydride species. The effects of activation on structure and surface chemistry of the alloy are also discussed. 相似文献
7.
In this work, the complex hydrogen sorption behaviors in a 3NaBH4/HoF3 composite prepared through mechanical milling were carefully investigated, including the reactions occurred during ball milling and de-/rehydrogenation processes. Different from other rear earth fluorides, the HoF3 can react with NaBH4 during ball milling, leading to the formations of Na–Ho–F and Na–Ho–BH4 complex compounds. The first dehydriding of the 3NaBH4/HoF3 composite can be divided into 4 steps, including the ion exchange between H− and F−, the formation of NaHo(BH4)4, the decomposition of NaHo(BH4)4 and reaction of NaBH4 with Na–Ho–F compounds. The final products, HoB4, HoH3 and NaF, can be rehydrogenated to generate NaBH4 and NaHoF4 with an absorption capacity of 2.3 wt% obtained at 400 °C. Based on the Pressure–Composition–Temperature measurements, the de-/rehydrogenation enthalpies of the 3NaBH4/HoF3 composite are determined to be 88.3 kJ mol−1 H2 and −27.1 kJ mol−1 H2, respectively. 相似文献
8.
Mei Qiang Fan Yu Wang Guang Lei Tian De sheng Mei Da Chen Kang Yin Shu 《International Journal of Hydrogen Energy》2013
Hydrogen generation from the hydrolysis of aluminum lithium/sodium borohydride (referred to as AlLi/NaBH4) system activated by Co powder with different particle size and amount was evaluated in this paper. The designed aluminum–lithium–cobalt (referred to as Al–Li–Co/NaBH4) systems including Al-5 wt% Li-50 wt% nano Co, Al-7.5 wt% Li-25 wt% nano Co, Al-5 wt% Li-50 wt% micro Co, and Al-7.5 wt% Li-25 wt% micro Co had 100% hydrogen yield at 323 K. The hydrogen generation rates of these systems were regulated by Co species, Co amount, as well as consecutive runs of NaBH4 hydrolysis. The underlying activation mechanism, including the formation of Al0.94Co1.06 alloy and highly active and stable Co-based catalyst has been elaborated in this study. Experimental data present an inexpensive and highly efficient hydrogen source for portable fuel cell. 相似文献
9.
Cheng-Hong Liu Yi-Chia Kuo Bing-Hung Chen Chan-Li Hsueh Kuo-Jen Hwang Jie-Ren Ku Fanghei Tsau Ming-Shan Jeng 《International Journal of Hydrogen Energy》2010
Solid-state composites of NaBH4 and Co-based catalyst have been fabricated for hydrogen generation via a novel mechanochemical technique, i.e. the high-energy ball milling, in which the gravimetric storage capacity of hydrogen has reached 6.7 wt%, meeting the 2010 target of at least 0.06 kg H2/kg set by the U.S. Department of Energy (DOE). The active catalysts used in the hydrolysis reaction of sodium borohydride for hydrogen generation are mainly cobalt oxides. Controlled addition of water, namely water used as a limiting agent, to the solid composites of NaBH4 and Co-based catalyst greatly improves the H2 storage capacity and resolved the issues of low gravimetric H2 storage in conventional aqueous system of sodium borohydride. Factors influencing the performance of hydrogen production such as amounts of H2O added, catalyst loadings and durations of ball-milling processes are investigated. Moreover the hydrolyzed products of NaBH4 and spent catalysts are analyzed as well. 相似文献
10.
In this paper we report the solution combustion synthesis of cobalt oxide nanofoam from solutions of cobalt nitrate and glycine and subsequent use as an effective catalyst precursor for NaBH4 hydrolysis. The catalytic activity results show that the hydrogen generation rate (HGR) at room temperature was much higher for the solution combustion synthesized material than for commercial Co3O4 nanopowder, though their specific surface areas were comparable (∼26–32 m2/g). Using a 0.6 wt.% aqueous solution of NaBH4 at 20 °C and a 5 wt.% catalyst precursor loading, a HGR of 1.93 L min−1 gcat−1 was achieved for solution combustion synthesized Co3O4. In contrast, at the same conditions, for commercial Co3O4 and elemental Co powders HGRs of 0.98 and 0.49 L min−1 gcat−1 were achieved respectively. This type of synthesis is amenable to many complex metal oxide catalysts as well, such as LiCoO2, which have also been shown to be good catalyst precursors for hydrolysis of NaBH4. 相似文献
11.
Sandra Kurko Annalisa Aurora Daniele Mirabile Gattia Vittoria Contini Amelia Montone Željka Rašković-Lovre Jasmina Grbović Novaković 《International Journal of Hydrogen Energy》2013
The hydrogen sorption properties of magnesium hydride–sodium borohydride composites prepared by means of high-energy ball milling under Ar atmosphere were investigated. Mutual influence of milling time and the content of NaBH4 were studied. Microstructural and morphological analyses were carried out using X-ray Diffraction (XRD), laser scattering measurements and Scanning Electron Microscopy (SEM), while kinetic analysis and cycling were performed in a Sievert's volumetric apparatus. It has been shown that low content of NaBH4 and short milling time are beneficial for hydrogen sorption kinetics. 相似文献
12.
Solid-state NaBH4/Ru-based catalyst composites have been fabricated for hydrogen generation through a high-energy ball-milling process, providing uniform dispersion of resin-supported Ru3+ catalysts among pulverized NaBH4 (SBH) particles, so as to increase the contacts of SBH with active catalytic sites. Consequently, the gravimetric hydrogen storage capacity as high as 7.3 wt% could be achieved by utilizing water as a limiting reagent to overcome the issue of deactivated catalysts whose active sites are often blocked by precipitates caused by limited NaBO2 solubility occurring in conventional aqueous SBH systems for hydrogen productions. Products of hydrolyzed SBH that greatly influence the gravimetric H2 storage capacity are found to be most likely NaBO2·2H2O and NaBO2·4H2O from SBH/H2O reacting systems with initial weight ratios, SBH/H2O = 1/2 and 1/10, respectively, according to the TGA and XRD analyses. 相似文献
13.
Anthony Garron Dariusz ŚwierczyńskiSimona Bennici Aline Auroux 《International Journal of Hydrogen Energy》2009
To our knowledge, the present study is the first investigation by liquid-phase calorimetry of the mechanism of hydrogen generation by hydrolysis of sodium borohydride catalyzed by Co2B nanoparticles generated in situ. The differential reaction calorimeter was coupled with a volumetric hydrogen measurement, allowing a simultaneous thermodynamic and kinetic study of the reaction. At the end of the reaction, the catalyst was characterized ex situ by TEM, XRD, magnetism, N2 adsorption, TGA–DTA, and the liquid hydrolysis products were analyzed by Wet-STEM and 11B-NMR. The in situ preparation method made it possible to form nanoparticles (<12 nm) of Co2B which are the active phase for the hydrolysis reaction. In semi-batch conditions, the Co2B catalyst formed in situ is subsequently reduced by each borohydride addition and oxidized at the end of the hydrolysis reaction by OH− in the presence of metaborate. A coating of the nanoparticles has been observed by calorimetry and physico-chemical characterization, corresponding to the formation of a 2–3 nm layer of cobalt oxide or hydroxide species. 相似文献
14.
The catalysts Rh/Al2O3 and Rh/TiO2 for hydrogen production from NaBH4 were prepared by deposition technique from RhCl3 reduced by NaBH4 and were studied by XPS and TEM. It was found that the RhCl3/Al2O3 system is more stable comparing to RhCl3/TiO2 which starts to decompose by weak heat treatment. It was shown that NaBH4 reduced RhCl3/TiO2 (Al2O3) to supported metal Rh nanoparticles in both cases. In the case of Rh/TiO2 SMSI effect it was found after RT reduction. The SMSI (Strong Metal-Support Interaction) effect gave an explanation for the difference of activity between Rh/TiO2 and Rh/Al2O3 catalysts in hydrolysis reaction of NaBH4. 相似文献
15.
Hyuck-Chul Kang Yingbo Chen Ernest Evans Arthur Hern Kim 《International Journal of Hydrogen Energy》2014
Polymer microcapsules were prepared and used as catalyst support for hydrogen generation from sodium borohydride. Polyvinylidene fluoride (PVDF) porous microcapsule membranes immobilized with metal salt (cobalt (II) chloride hexahydrate) catalyst and cobalt–boron catalyst were prepared, denoting them as MS and MP method respectively. Non-solvent coagulation bath consisting of a mixture of water and isopropanol (IPA) were used to prepare the microcapsules. The compositions of the non-solvents were changed with a ratio of 10:90 (v/v%)–50:50 (v/v%) with 1 wt% NaOH and 0.5 wt% NaBH4. The effects of a number of parameters such as the kinds of additives, the size and morphology of the resulting microcapsules were studied on hydrogen generation. The structures and physical–chemical properties of the metal catalyst-loaded microcapsule membranes were characterized using SEM and EDX. The MS method used in preparing the microcapsule showed good performance in hydrogen generation from sodium borohydride. There was also improved performance in hydrogen generation with increasing IPA composition used in the metal salts loaded microcapsule preparation. The control of three regions inside the microcapsules (hollow region, crust region and skin layer) as well as the specific loading of metal catalysts gave a good hydrogen generation performance. The catalyst-loaded microcapsule also maintained an appreciable performance and stability after many runs of hydrolysis reaction for the hydrogen generation. 相似文献
16.
Thermochemical recycling of hydrolyzed NaBH4. Part II: Systematical study of parameters dependencies
This paper focuses on the yields of both main product NaBH4 and byproduct MgH2 of the thermochemical process. The influence of parameters such as i) the isothermal reaction temperature in the range 480 °C–660 °C, ii) the stoichiometric ratio of solid reactants NaBO2:Mg prepared from 1:2 to 1:8, iii) H2 pressure supplied from 2 to 31 bars and iv) the reaction time kept at isotherm from 0 to 16 h have been systematically investigated. The yields are estimated by in-situ and ex-situ evaluations. Two temperature regimes for MgH2 and NaBH4 formation are recognized from 370 °C to 450 °C and above 500 °C respectively. With regard to NaBH4 regeneration, temperature is the most important factor that positively accelerates the apparent reaction rate between 500 °C and 650 °C providing a sufficient H2 pressure. To efficiently obtain high NaBH4 yield mixtures with molar stoichiometric ratio between solid reactants not less than 1:4 is suggested. Experimental results also reveal that at 12 bars of H2 pressure high NaBH4 yield is obtained. Hence, more efficient way to improve mass transfer of solid reactants (e.g. advance reactor enhances mobility of reactants) rather than increasing H2 pressures is advised. Under optimized condition, 100% conversion of NaBO2 can be achieved within 1.5 h. 相似文献
17.
Jianfeng MaoZaiping Guo Xuebin Yu Mohammad IsmailHuakun Liu 《International Journal of Hydrogen Energy》2011,36(9):5369-5374
The mutual destabilization of LiAlH4 and MgH2 in the reactive hydride composite LiAlH4-MgH2 is attributed to the formation of intermediate compounds, including Li-Mg and Mg-Al alloys, upon dehydrogenation. TiF3 was doped into the composite for promoting this interaction and thus enhancing the hydrogen sorption properties. Experimental analysis on the LiAlH4-MgH2-TiF3 composite was performed via temperature-programmed desorption (TPD), differential scanning calorimetry (DSC), isothermal sorption, pressure-composition isotherms (PCI), and powder X-ray diffraction (XRD). For LiAlH4-MgH2-TiF3 composite (mole ratio 1:1:0.05), the dehydrogenation temperature range starts from about 60 °C, which is 100 °C lower than for LiAlH4-MgH2. At 300 °C, the LiAlH4-MgH2-TiF3 composite can desorb 2.48 wt% hydrogen in 10 min during its second stage dehydrogenation, corresponding to the decomposition of MgH2. In contrast, 20 min was required for the LiAlH4-MgH2 sample to release so much hydrogen capacity under the same conditions. The hydrogen absorption properties of the LiAlH4-MgH2-TiF3 composite were also improved significantly as compared to the LiAlH4-MgH2 composite. A hydrogen absorption capacity of 2.68 wt% under 300 °C and 20 atm H2 pressure was reached after 5 min in the LiAlH4-MgH2-TiF3 composite, which is larger than that of LiAlH4-MgH2 (1.75 wt%). XRD results show that the MgH2 and LiH were reformed after rehydrogenation. 相似文献
18.
Bo Chen Sijiang Chen Harshad A. Bandal Richard Appiah-Ntiamoah Amol R. Jadhav Hern Kim 《International Journal of Hydrogen Energy》2018,43(19):9296-9306
A novel recyclable cobalt nanocatalyst, supported on magnetic carbon with core-shell structure, was successfully synthesized by using wetness impregnation-chemical reduction method for hydrogen generation from hydrolysis of NaBH4. The resultant nanocomposite was characterized to determine the structural and physical-chemical properties by a series of analytical techniques such as FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscope), EDX (energy-dispersive X-ray spectroscopy), TEM (transmission electron microscopy), etc. The results demonstrated that amorphous cobalt nanoparticles were homogeneously surrounded on the surface of the support due to having abundant hydrophilic groups (such as aldehyde and hydroxyl groups) on the surface of carbon layer for the effective immobilization of metal ions. The supported catalyst showed superior catalytic performance towards the hydrolysis reaction of NaBH4 at room temperature. The total rate of hydrogen generation and activation energy were calculated to be 1403 ml H2 gcat?1 min?1 and 49.2 kJ mol?1, respectively, which were comparable to the values of most cobalt-based catalyst reported for hydrogen production from hydrolysis of NaBH4. Additionally, reusability test revealed that the hydrogen in NaBH4 substrate could be completely released within 25 min with a minimum hydrogen generation rate of 832 ml H2 gcat?1 min?1 even after five runs of hydrolytic reaction, implying the as-prepared Co/Fe3O4@C composite could be considered as a promising candidate catalyst for portable hydrogen fuel system such as PEMFC (proton exchange membrane fuel cells). 相似文献
19.
Chan-Li HsuehCheng-Hong Liu Bing-Hung ChenMing-San Lee Cheng-Yen ChenYu-Wen Lu Fanghei TsauJie-Ren Ku 《Journal of power sources》2011,196(7):3530-3538
Hydrolysis of sodium borohydride (NaBH4) is a promising method for on-board hydrogen supply to polymer electrolyte membrane fuel cells (PEMFC). This article presents an attempt to design a novel solid-state NaBH4 composite, which is made up of NaBH4 powder, Co2+/IR-120 catalyst and silicone rubber, for hydrogen generator. The silicone rubber can act as a stabilizer in the solid-state NaBH4 composite because of its surface hydrophobicity leading to reduced diffusion rate of water into the composite. The solid-state NaBH4 composite can produce hydrogen stably near 25 mL min−1 for at least 2 h without employment of any mechanical control system. Using the hydrogen generated from the solid-state NaBH4 composite, a 2 W PEMFC stack is successfully operated to power a cellular phone. 相似文献
20.
The composites of (NaBH4+2Mg(OH)2) and (LiBH4+2Mg(OH)2) without and with nanometric Ni (n-Ni) added as a potential catalyst were synthesized by high energy ball milling. The ball milled NaBH4-based composite desorbs hydrogen in one exothermic reaction in contrast to its LiBH4-based counterpart which dehydrogenates in two reactions: an exothermic and endothermic. The NaBH4-based composite starts desorbing hydrogen at 240 °C. Its ball milled LiBH4-based counterpart starts desorbing at 200 °C. The latter initially desorbs hydrogen rapidly but then the rate of desorption suddenly decelerates. The estimated apparent activation energy for the NaBH4-based composite without and with n-Ni is equal to 152 ± 2.2 and 157 ± 0.9 kJ/mol, respectively. In contrast, the apparent activation energy for the initial rapid dehydrogenation for the LiBH4-based composite is very low being equal to 47 ± 2 and 38 ± 9 kJ/mol for the composite without and with the n-Ni additive, respectively. XRD phase studies after volumetric isothermal dehydrogenation tests show the presence of NaBO2 and MgO for the NaBH4-based composite. For the LiBH4-based composite phases such as MgO, Li3BO3, MgB2, MgB6 are the products of the first exothermic reaction which has a theoretical H2 capacity of 8.1 wt.%. However, for reasons which are not quite clear, the first reaction never goes to full completion even at 300 °C desorbing ∼4.5 wt.% H2 at this temperature. The products of the second endothermic reaction for the LiBH4-based composite are MgO, MgB6, B and LiMgBO3 and the reaction has a theoretical H2 capacity of 2.26 wt.%. The effect of the addition of 5 wt.% nanometric Ni on the dehydrogenation behavior of both the NaBH4-and LiBH4-based composites is rather negligible. The n-Ni additive may not be the optimal catalyst for these hydride composite systems although more tests are required since only one n-Ni content was examined. 相似文献