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1.
Density functional theory calculations of an interaction of LiBH4 represented by n = 2−6 and 12 formula units nanoclusters with models of activated carbon and porous silica show that on both non-defective substrates only physisorption is observed for all cluster sizes. The binding energies are low, reaching up to −43 kJ/mol for smallest clusters. The charge transfer between LiBH4 and the support is not observed. On defective graphene (LiBH4)2 may adsorbed dissociatively. Hydrogens detached from BH4 groups saturates under-coordinated C atoms while the binding between BH3 moiety and underlying C atoms restores sp3-hybridization in the BH4 group. The dissociative adsorption of LiBH4 clusters leads to the retrieval of the three-fold coordination of the C atoms, the subsequent (LiBH4)2 physisorps with the differential heat of adsorption not exceeding −46 kJ/mol. The present calculations indicate that chemical interaction between matrix and lithium borohydride, leading to a destabilization of LiBH4, takes place until substrate's defects remain unsaturated. 相似文献
2.
Junhong Luo Hui Wu Wei Zhou Xiangdong Kang Zhanzhao Fang Ping Wang 《International Journal of Hydrogen Energy》2012
Mechanically milling ammonia borane and lithium borohydride in equivalent molar ratio results in the formation of a new complex, LiBH4·NH3BH3. Its structure was successfully determined using combined X-ray diffraction and first-principles calculations. LiBH4·NH3BH3 was carefully studied in terms of its decomposition behavior and reversible dehydrogenation property, particularly in comparison with the component phases. In parallel to the property examination, X-ray diffraction and Fourier transformation infrared spectroscopy techniques were employed to monitor the phase evolution and bonding structure changes in the reaction process. Our study found that LiBH4·NH3BH3 first disproportionates into (LiBH4)2·NH3BH3 and NH3BH3, and the resulting mixture exhibits a three-step decomposition behavior upon heating to 450 °C, totally yielding ∼15.7 wt% hydrogen. Interestingly, it was found that h-BN was formed at such a moderate temperature. And owing to the in situ formation of h-BN, LiBH4·NH3BH3 exhibits significantly improved reversible dehydrogenation properties in comparison with the LiBH4 phase. 相似文献
3.
R.A. Varin L. Zbroniec M. Polanski Y. Filinchuk R. Černý 《International Journal of Hydrogen Energy》2012
Manganese borohydride (Mn(BH4)2) was successfully synthesized by a mechano-chemical activation synthesis (MCAS) from lithium borohydride (LiBH4) and manganese chloride (MnCl2) by applying high energy ball milling for 30 min. For the first time a wide range of molar ratios n = 1, 2, 3, 5, 9 and 23 in the (nLiBH4 + MnCl2) mixture was investigated. During ball milling for 30 min the mixtures release only a very small quantity of H2 that increases with the molar ratio n but does not exceed ∼0.2 wt.% for n = 23. However, longer milling duration leads to more H2 released. For the equimolar ratio n = 1 the principal phases synthesized are Li2MnCl4, an inverse cubic spinel phase, and the Mn(BH4)2 borohydride. For n = 2 a LiCl salt is formed which coexists with Mn(BH4)2. With the n increasing from 3 to 23 LiBH4 is not completely reacted and its increasing amount is retained in the microstructure coexisting with LiCl and Mn(BH4)2. Gas mass spectrometry during Temperature Programmed Desorption (TPD) up to 450 °C shows the release of hydrogen as a principal gas with a maximum intensity around 130–150 °C accompanied by a miniscule quantity of borane B2H6. The intensity of the B2H6 peak is 200–600 times smaller than the intensity of the corresponding H2 peak. In situ heating experiments using a continuous monitoring during heating show no evidence of melting of Mn(BH4)2 up to about 270–280 °C. At 100 °C under 1 bar H2 pressure the ball milled n = 2 and 3 mixtures are capable of desorbing quite rapidly ∼4 wt.% H2 which is a very large amount of H2 considering that the mixture also contains 2 mol of LiCl salt. The H2 quantities experimentally desorbed at 100 and 200 °C do not exceed the maximum theoretical quantities of H2 expected to be desorbed from Mn(BH4)2 for various molar ratios n. It clearly confirms that the contribution from B2H6 evolved is negligibly small (if any) when desorption occurs isothermally in the practical temperature range 100–200 °C. It is found that the ball milled mixture with the molar ratio n = 3 exhibits the highest rate constant k and the lowest apparent activation energy for dehydrogenation, EA ∼ 102 kJ/mol. Decreasing or increasing the molar ratio n below or above 3 increases the apparent activation energy. Ball milled mixtures with the molar ratio n = 2 and 3 discharge slowly H2 during storage at room temperature and 40 °C. The addition of 5 wt.% nano-Ni with a specific surface area of 60.5 m2/g substantially enhances the rate of discharge at 40 °C. 相似文献
4.
Baicheng Weng Zhu WuZhilin Li Hui YangHaiyan Leng 《International Journal of Hydrogen Energy》2011,36(17):10870-10876
Ammonia borane (NH3BH3) and lithium borohydride (LiBH4) are promising hydrides as they contain 19.6 wt.% and 18.5 wt.% hydrogen respectively. However, hydrolysis of NH3BH3 needs catalysts or high temperature to initiate the release of hydrogen. On the other hand, hydrolysis of LiBH4 is incomplete, because the agglomeration of LiBH4 and its products limits its full utilization. In the present work, hydrolysis performance of LiBH4/NH3BH3 mixture was investigated. The results show that LiBH4/NH3BH3 mixture can fully release its theoretical amount of hydrogen at room temperature without catalysts. In the presence of LiBH4, NH3BH3 can be fully hydrolyzed at room temperature. In return, in the presence of NH3BH3, the agglomeration can be avoided resulting in a complete hydrolysis process. Our results indicate that the improvements are attributed to the intermolecular electron migration between LiBH4 and NH3BH3, which changes the reactivity of these compounds. Hydrolytic heat of LiBH4 also contributes to the promoted hydrolysis of NH3BH3. Our results present a novel strategy for noncatalytic hydrolysis of NH3BH3 and LiBH4 for proton exchange membrane fuel cell applications. 相似文献
5.
A novel lithium amidoborane borohydride complex, Li2(NH2BH3)(BH4), was synthesized using mechanochemical method and its crystal structure was successfully determined by a combination of X-ray diffraction (XRD) analysis and first-principles calculations. Interestingly, this compound does not exist as a pure phase, but requires almost equivalent amount of amorphous LiAB as a stabilizing agent. In this paper, we report a careful study of the structure, property, and dehydrogenation mechanism of the 1:1 Li2(NH2BH3)(BH4)/LiAB composite. This composite can release ∼8 wt% H2 at 100 °C via a two-step dehydrogenation process, with dehydrogenation kinetics better than the parenting phases. The composite and its dehydrogenation products were characterized by the combined XRD, Fourier transformation infrared (FTIR) spectroscopy, and solid-state 11B MAS NMR techniques. Selective deuterium labeling was performed to elucidate a reaction sequence for the hydrogen release by analyzing the released gases. 相似文献
6.
In the present study, we employed a multi-component combination strategy to constitute an AB/LiNH2/LiBH4 composite system. Our study found that mechanically milling the AB/LiNH2/LiBH4 mixture in a 1:1:1 molar ratio resulted in the formation of LiNH2BH3 (LiAB) and new crystalline phase(s). A spectral study of the post-milled and the relevant samples suggests that the new phase(s) is likely ammoniate(s) with a formula of Li2−x(NH3)(NH2BH3)1−x(BH4) (0 < x < 1). The decomposition behaviors of the Li2−x(NH3)(NH2BH3)1−x(BH4)/xLiAB composite were examined using thermal analysis and volumetric method in a wide temperature range. It was found that the composite exhibited advantageous dehydrogenation properties over LiAB and LiAB·NH3 at moderate temperatures. For example, it can release ∼7.1 wt% H2 of purity at temperature as low as 60 °C, with both the dehydrogenation rate and extent far exceeding that of LiAB and LiAB·NH3. A selectively deuterated composite sample has been prepared and examined to gain insight into the dehydrogenation mechanism of the Li2−x(NH3)(NH2BH3)1−x(BH4)/xLiAB composite. It was found that the LiBH4 component does not participate in the dehydrogenation reaction at moderate temperatures, but plays a key role in strengthening the coordination of NH3. This is believed to be a major mechanistic reason for the favorable dehydrogenation property of the composite at moderate temperatures. 相似文献
7.
Yun Song Fang Fang Yongtao Li Qiyang Zhao Dalin Sun Qingan Zhang Liuzhang Ouyang Min Zhu 《International Journal of Hydrogen Energy》2012
The evolution of diborane accompanying H2 release during the decomposition of transition metal borohydrides reduces the purity of evolved hydrogen and results in capacity loss during cycling. To solve the problem, a small amount of LiNH2 is doped into a 3LiBH4/MnF2 composite and the decomposition properties are investigated. The results show that after doping LiNH2, the formation of diborane during decomposition is effectively suppressed meanwhile the decomposition temperature is significantly reduced. Around 5 wt.% pure hydrogen can be released at 95–140 °C from 5 wt.% LiNH2-doped 3LiBH4/MnF2 composite. These improvements in the decomposition performance are mainly attributed to the prevention of the formation of B–H–B bonds for B2H6 and the destabilization of B–H bonds in borohydrides by the interaction of BH4− and NH2−. 相似文献
8.
Julien Hannauer Umit B. Demirci Christophe Geantet Jean-Marie Herrmann Philippe Miele 《International Journal of Hydrogen Energy》2012
Hydrazine borane N2H4BH3 (denoted HB) is a novel candidate in hydrogen generation by catalytic hydrolysis. The challenge with this material is the dehydrogenation of the N2H4 moiety, which occurs after the hydrolysis of the BH3 group. This challenge requires the utilization of a reactive and selective metal-based catalyst. In this work, we considered various transition metal salts as precursors of in situ forming catalysts by reduction in the presence of HB. According to their reactivity, the metals studied can be classified into 3 groups: (1) Fe- and Re-based catalysts, showing a limited reactivity in the hydrolysis of the BH3 group; (2) Co-, Ni-, Cu-, Pd-, Pt- and Au-based catalysts, only active in the hydrolysis of BH3 (3 mol H2 per mol HB generated); (3) Ru-, Rh, and Ir-based catalysts, being also active in the decomposition of N2H4. With the Rh-based catalyst, characterized as agglomerated Rh0 nanorods (10 × 4 nm) by XRD, TEM, SAED and XPS, 4.1 mol H2 + N2 per mol HB can be produced at 50 °C. Rhodium is thus a possible candidate for synthesizing nanosized particles and bimetallic nanoalloys in order to tune its reactivity and increase its selectivity up to the targeted conversion of 100%. Our main results are reported herein and the behavior of the metals is discussed. 相似文献
9.
Juan Xu Rongrong Meng Jianyu Cao Xiaofang Gu Zhongqing Qi Wenchang Wang Zhidong Chen 《International Journal of Hydrogen Energy》2013
The investigation of thermally induced dehydrogenation of LiBH4 reveals that LiBH4 doped with the graphene catalysts shows superior dehydrogenation and rehydrogenation performance to that of Vulcan XC-72, carbon nanotube and BP2000 doped LiBH4. For doping with 20 wt.% graphene, thermal dehydrogenation of LiBH4 is found to start at ca. 230 °C and a total weight loss of 11.4 wt.% can be obtained below 700 °C. With increased loading of graphene within a LiBH4 sample, the onset dehydrogenation temperature and the two main desorption peaks from LiBH4 are found to decrease while the hydrogen release amount is found to increase. Moreover, variation of the equilibrium pressure obtained from isotherms measured at 350–450 °C indicate the dehydrogenation enthalpy is reduced from 74 kJ mol−1 H2 for pure LiBH4 to ca. 40 kJ mol−1 H2 for 20 wt.% graphene doped LiBH4. Importantly, the reversible dehydrogenation/rehydrogenation process was achieved under 3 MPa H2 at 400 °C for 10 h, with a capacity of ca. 4.0 wt.% in the tenth cycle. Especially, LiBH4 is reformed and new species, Li2B10H10, is detected after the rehydrogenation process. 相似文献
10.
《International Journal of Hydrogen Energy》2020,45(33):16634-16643
Alkali hydrazinidoboranes MN2H3BH3 (M = Li, Na, K, Rb) have been developed for hydrogen storage. To complete the family of MN2H3BH3, we focused on cesium hydrazinidoborane CsN2H3BH3 (CsHB). It has been synthesized by reaction of cesium with hydrazine borane (N2H4BH3) at −20 °C under inert atmosphere, and it has been characterized. A crystalline solid (monoclinic, s.g. P21 (No. 4)) has been obtained. Its potential for hydrogen storage has been studied by combining different techniques. It was found that, under heating at constant heating rate (5 °C min−1) or at constant temperature (e.g. 120 °C), CsHB decomposes rather than it dehydrogenates. It releases several unwanted gaseous products (e.g. NH3, B2H6) together with H2, and transforms into a residue that poses safety issues because of shock-sensitivity and reactivity towards O2/H2O. Though the destabilization brought by Cs+ onto the anion [N2H3BH3]− has been confirmed, the effect is not efficient enough to avoid the aforementioned drawbacks. All of our results are presented herein and discussed within the context of solid-state hydrogen storage. 相似文献
11.
Successful synthesis of LiBH4·NH3 confined in nanoporous silicon dioxide (LiBH4·NH3@SiO2) was achieved via a new “ammonia-deliquescence” method, which avoids the involvement of any solvents during the process of synthesis. Compared to the pure LiBH4·NH3, the confined LiBH4·NH3@SiO2 exhibited significantly improved dehydrogenation properties, which not only suppressed the emission of NH3, but also decreased the onset dehydrogenation temperature to 60 °C, thus leading to an enhanced conversion of NH3 to H2. In the temperature range of 60–300 °C, the mole ratio of H2 release for the confined LiBH4·NH3@SiO2 is 85 mol % of the total gas evolved, compared to 2.66 mol % for the pristine LiBH4·NH3. Isothermal dehydrogenation results showed that the LiBH4·NH3@SiO2 is able to release about 1.26, 2.09, and 2.35 equiv. of hydrogen, at 150 °C, 200 °C, and 250 °C, respectively. From analysis of the Fourier transform infrared, Raman, and nuclear magnetic resonance spectra of the confined LiBH4·NH3@SiO2 sample heated to various temperatures, as well as its dehydrogenation product under NH3 atmosphere, it is proposed that the improved dehydrogenation of LiBH4·NH3@SiO2 is mainly attributable to two crucial factors resulting from the nanoconfinement: (1) stabilization of the NH3 in the nanopores of SiO2, and (2) enhanced combination of LiBH4 and NH3 groups, leading to fast dehydrogenation at low temperature. 相似文献
12.
《International Journal of Hydrogen Energy》2019,44(14):7392-7401
The possibility of hydrogen generation by hydrolysis of magnesium borohydride and its ammoniates was explored. Results show that catalyst-free Mg(BH4)2 can generate 1700 mL (H2)·g−1 in 1 min, 2760 mL (H2)·g−1 in 2 h, and 3004 mL (H2)·g−1 in 5 h without any diborane (B2H6) emission. Mg(BH4)2 presents the highest hydrogen yield reported to date. However, the hydrogen generation rate of Mg(BH4)2 may be too fast to be controllable in some hydrogen production cases. Therefore, NH3 was added to form ammoniates to further regulate the hydrogen supply kinetics of Mg(BH4)2. The hydrogen yields of Mg(BH4)2·0.5NH3, Mg(BH4)2·NH3, Mg(BH4)2·2NH3, Mg(BH4)2·3NH3 and Mg(BH4)2·6NH3 are 2376, 2029, 1780, 1665 and 1180 mL (H2) g−1, respectively, which demonstrates a well-controlled hydrogen supply rate. These results indicate that catalyst-free Mg(BH4)2 and its ammoniates have good hydrolysis performance and show promise as convenient high-density hydrogen generation materials. 相似文献
13.
C. Rongeat I. LindemannA. Borgschulte L. SchultzO. Gutfleisch 《International Journal of Hydrogen Energy》2011,36(1):247-253
Calcium borohydride is one of the most interesting compounds for solid-state hydrogen storage, in particular because of its high hydrogen capacity. In this paper, the synthesis of Ca(BH4)2 by metathesis reaction via ball milling of a mixture of LiBH4 and CaCl2 is described. The effectiveness of this synthesis technique and the possible substitution of Cl ions in the borohydride phases is analysed depending on the back-pressure used for milling. When performed by ball milling under Ar, the metathesis reaction is not successful. A large quantity of a solid solution Li(BH4)1−xClx remains in the sample and CaHCl is formed rather than Ca(BH4)2. In contrast, the use of H2 back-pressure during milling favours the borohydride phases rather than CaHCl and leads to the formation of a solid solution Ca(BH4)2-yCly where [BH4]− groups are partially substituted by Cl ions. This compound has a similar structure as β-Ca(BH4)2 but with smaller lattice parameters. It is present in the as-milled sample together with LiCl and Li(BH4)1−xClx. The decomposition of the mixture occurs at lower temperature than for pure LiBH4 but higher than for pure Ca(BH4)2. The presence of chlorides in the structure of borohydride compounds changes dramatically the thermal properties of the material prepared and should be considered each time a metathesis reaction is used for synthesis. 相似文献
14.
Nickel-based bimetallic catalysts were screened using the sodium borohydride NaBH4 hydrolysis and the aqueous hydrazine borane N2H4BH3 dehydrogenation. A total of 22 bimetallic catalysts were synthesized according to an easy process while focusing on metals like Fe, Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt and Au. In the end, the bimetallic candidate Ni87.5Pt12.5 showed to be the most active and the most selective for the dehydrogenation of N2H4BH3. At 70?°C, it is able to decompose N2H4BH3 into 5.8 equivalents of H2+N2 in less than 12?min such as: N2H4BH3?+?3H2O?→?0.95 N2?+?0.1 NH3?+?B(OH)3?+?4.85H2. Durability and stability tests were also performed. In our conditions, Ni87.5Pt12.5 was found to suffer from small loss of performance because of an electronic evolution of the catalytic surface leading to modified sorption properties of the catalytic sites. Our main results are reported and discussed herein. 相似文献
15.
This study shows the hydrogen desorption kinetics and reversible hydrogen storage properties of 0.55LiBH4–0.45Mg(BH4)2 melt-infiltrated in different nanoporous carbon aerogels with different BET surface areas of 689 or 2660 m2/g and pore volumes of 1.21 or 3.13 mL/g. These investigations clearly show a significantly improved hydrogen storage capacity after four cycles of hydrogen release and uptake for bulk 0.55LiBH4–0.45Mg(BH4)2 and infiltrated in carbon aerogel and the high surface area scaffold, where 22, 36 and 58% of the initial hydrogen content remain after four cycles of hydrogen release and uptake, respectively. Nanoconfinement in high surface area carbon aerogel appears to facilitate hydrogen release illustrated by release of 13.3 wt% H2 (93%) and only 8.4 wt% H2 (58%) from bulk hydride in the first cycle using the same physical condition. Notably, nanoconfinement also appear to have a beneficial effect on hydrogen uptake, since 8.3 wt% H2 (58%) is released from the high surface area scaffold and only 3.1 wt% H2 (22%) from the bulk sample during the fourth hydrogen release. 相似文献
16.
A series of mixtures of LiAB/LiBH4 with different molar ratios were prepared and their hydrogen storage properties were investigated in this study. Among them, a new structure was found in the LiAB/LiBH4 sample with a molar ratio of 1/1. It is of orthorhombic structure and composed of alternative layers of LiAB and LiBH4. It shows similar hydrogen desorption behaviors of LiAB–LiBH4 and LiAB–0.5LiBH4. For use in hydrogen storage, high hydrogen capacity and low operation temperature are demanded, thus, the dehydrogenation properties of LiAB–0.5LiBH4 were subsequently measured. Three steps of desorption were observed during the heating process, with a total release of 11.5 wt% H2 at 500 °C. The reaction path was identified using a combined investigation of XRD and 11B solid state NMR. Dehydrogenation kinetic analyses show that the complex has lower activation energy (61 ± 4 kJ mol−1 H2) than that of LiAB (71 ± 5 kJ mol−1 H2). It is likely that dehydrogenation process was promoted due to the presence of LiBH4. 相似文献
17.
《International Journal of Hydrogen Energy》2019,44(20):9883-9895
Electrospun nanofibers are prepared through electrospinning followed by post-treatment and preferred to use in catalytic applications. The electrospinning provides advantages for active catalysts design based on activity profiles and features of catalyst. In the present study, we fabricated nano-crystalline cobalt oxide (Co3O4) catalyst by electrospinning technique followed by thermal conditioning. Polyacrylonitrile (PAN) based Co as-spun mats (Co/NMs) with homogeneous diameter were prepared by electrospinnig process under several conditions as applied voltage (15–25 kV), working distance (5–7.5 cm) with the feed rate of 1 ml min−1. The calcination process as a post-treatment was applied at different temperatures (232 °C, 289 °C and 450 °C) to obtain electrospun nano-crystalline Co3O4 catalyst. Co/NMs catalysts were characterized by XRD, SEM, TEM, XPS, FT-IR, TG/DTG, and ICP-MS techniques. The parametrically study was performed for evaluating the hydrogen production activity of catalyst from sodium borohydride (NaBH4, SBH) and its originated compounds as ammonia borane (NH3BH3, AB) and methyl-amine borane (CH3NH2BH3, MeAB). The relation between the internal-external properties and catalytic activities of catalysts for hydrogen production was investigated. The beadless Co/NMs-1 catalyst with homogeneous diameter was obtained under electrospinnig process conditions at 15 kV applied voltage and 7.5 cm working distance. All catalysts showed activity for hydrogen production, also the significant effect of post treatment process was observed on the catalytic activity as given order: Co/NMs-1450 > Co/NMs-1289 > Co/NMs-1 > Co/NMs-1232. Furthermore, mesoporous Co3O4 cubic crystals (26 nm) in fibrous architecture was prepared by 450 °C-post-treatment. Hydrogen production rates were recorded at 60 °C as 2.08, 2.20, and 6.39 l H2.gcat−1min−1 for NaBH4, CH3NH2BH3, and NH3BH3, respectively. 相似文献
18.
The significantly enhanced dehydrogenation performance of binary complex system, NH3BH3/LiBH4·NH3, were achieved through a chemical modification of LiH to form ternary composites of x (LiH–NH3BH3)/LiBH4·NH3. Among the studied composites, 3LiH–3NH3BH3/LiBH4·NH3 released ca. 10 wt. % high-pure hydrogen (>99.9 mol%) below 100 °C with fast kinetics, while less than 8 wt. % hydrogen, accompanied with a fair number of volatile byproducts, were released from 3NH3BH3/LiBH4·NH3 at the same conditions. Further investigations revealed that the hydrogen emission from x (LiH–NH3BH3)/LiBH4·NH3 composites is based on the combination mechanism of Hδ+ and Hδ− through the interaction between LiH–NH3BH3 and NH3 group in LiBH4·NH3, in which the controllable protic hydrogen source from the stabilized NH3 group played a crucial role in providing optimal stoichiometric ratio of Hδ+ and Hδ−, and thus leading to the significant improvement of dehydrogenation capacity and purity. 相似文献
19.
A new hydrogen storage system NaZn(BH4)3?2NH3-nNH3BH3 (n = 1–5) was synthesized via a simple ball milling of NaZn(BH4)3?2NH3 and NH3BH3 (AB) with a molar ratio from 1 to 5. Dehydrogenation results revealed that NaZn(BH4)3?2NH3-nAB (n = 1–5) showed a mutual dehydrogenation improvement in terms of significant decrease in the dehydrogenation temperature and preferable suppression of the simultaneous evolution of by-products (i.e. NH3, B2H6 and borazine) compared to the unitary compounds (NaZn(BH4)3?2NH3 and AB). Specially, the NaZn(BH4)3?2NH3-4AB sample is shown to reach the maximum hydrogen purity (99.1 mol %) and favorable dehydrogenation properties rapidly releasing 11.6 wt. % of hydrogen with a peak maximum temperature of 85 °C upon heating to 250 °C. Isothermal dehydrogenation results revealed that 9.6 wt. % hydrogen was liberated from NaZn(BH4)3?2NH3-4AB within 80 min at 90 °C. High-resolution in-situ XRD and Fourier transform infrared (FT-IR) measurements indicated that the significant improvements on the dehydrogenation properties in NaZn(BH4)3?2NH3-4AB can be attributed to the interaction between the NH3 group from NaZn(BH4)3?2NH3 and AB in the mixture, resulting a more activated Hδ+···−δH combination. The research on the reversibility of the spent fuels of NaZn(BH4)3?2NH3-4AB showed that regeneration could be partly achieved by reacting them with hydrazine in liquid ammonia. These aforementioned favorable dehydrogenation properties demonstrate the potential of the combined systems to be used as solid hydrogen storage material. 相似文献
20.
Leigang Li Jianmei Huang Meng Li Qian Li Liuzhang Ouyang Min Zhu Xuebin Yu 《International Journal of Hydrogen Energy》2013
Two new cobalt-based ammine borohydrides were prepared via ball milling of LiBH4 and CoCln·3NH3 (n = 3, 2) with molar ratios of 3:1 and 2:1, respectively. X-ray diffraction (XRD) results revealed the as-prepared composites having amorphous state. Thermogravimetric analysis-mass spectrometry (TG-MS) measurements showed that the two composites mainly release H2, concurrent with the evolution of a small amount of NH3. Further results showed that the excessive addition of LiBH4 can suppress the liberation of NH3, resulting in the release of H2 with a high purity (>99 mol.%). By combination with the temperature-programmed-desorption (TPD) results, the CoCl3·3NH3/4LiBH4 and CoCl2·3NH3/3LiBH4composites can release 7.3 wt.% (4.2 wt.% including LiCl) and 4.2 wt.% (2.0 wt.% including LiCl) pure hydrogen, respectively, in the temperature range of 25–300 °C. Isothermal dehydrogenation results reveal that CoCl3·3NH3/3LiBH4 shows favorable dehydrogenation rate at low temperatures, releasing about 5.2 wt.% (2.9 wt.% including LiCl) of hydrogen within 45 min at 80 °C. 相似文献