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NaBH4–NH3BH3 composites were prepared by high-energy ball-milling processes for hydrogen generation through hydrolysis. After ball milling, there were no new phases found in the XRD patterns of NaBH4–NH3BH3 composites. The experimental results demonstrate that when the molar ratios of NaBH4–NH3BH3 composites range from 1:4 to 2:1, these composites can release above 90% hydrogen in 30 min at 70 °C. Comparing with neat NaBH4 or NH3BH3, the hydrolysis properties of these composites are greatly enhanced. And the hydrolysis reaction mechanism is turned out to be more explicit as Na2B4O5(OH)4·8H2O appears in the hydrolysis products. Since the preparation processes of these composites are simple and cost-effective and the hydrolysis of these composites achieves efficient hydrogen release, it is promising that this kind of composites can be applied in hydrogen generation. 相似文献
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基于介质阻挡放电理论设计一套低温等离子体(non-thermal plasmal,NTP)发生器。采用溶胶-凝胶法制备了钙钛矿催化剂La0.8K0.2MnO3(LKMO)和LaMnO3(LMO),并利用X射线衍射分析(X-ray diffraction,XRD)对其性能进行表征。通过柴油机台架试验,研究了NTP辅助LKMO和LMO催化对NOx的作用规律。研究结果表明:制备的催化剂形成了钙钛矿晶体结构,温度在200~350℃时,NTP辅助LMO只存在NO和NO2的吸附和脱附,而NOx总量未降低;在NTP辅助LKMO作用下,NOx浓度降低较明显,K元素的掺入提高了催化剂活性,且NTP提高了催化剂对NOx的去除效率。 相似文献
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采用管式炉研究了在O2/CO2气氛下添加CaCO3对PM2.5(空气动力学直径小于2.5,μm的颗粒物)排放特性的影响.试验采用荷电低压撞击器(ELPI)采集和分析燃烧后的PM2.5.结果表明,添加CaCO3是燃烧过程中影响PM2.5生成的重要因素.添加CaCO3后,生成PM1的数密度和质量浓度均降低,而PM1-2.5的数密度和质量浓度均略有增加,PM2.5粒径分布均呈双峰分布,峰值点分别出现在0.2,μm和2.0,μm左右.随着CaCO3添加质量分数的增加,PM2.5中的S、Pb、Cu、Na和K几种元素的浓度呈下降趋势. 相似文献
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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
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Hujun Cao Yongshen Chua Yao Zhang Zhitao Xiong Guotao Wu Jieshan Qiu Ping Chen 《International Journal of Hydrogen Energy》2013
Ball milling the mixture of Mg(NH2)2, LiH and NH3BH3 in a molar ratio of 1:3:1 results in the direct liberation of 9.6 wt% H2 (11 equiv. H), which is superior to binary systems such as LiH–AB (6 equiv. H), AB–Mg(NH2)2 (No H2 release) and LiH–Mg(NH2)2 (4 equiv. H), respectively. The overall dehydrogenation is a three-step process in which LiH firstly reacts with AB to yield LiNH2BH3 and LiNH2BH3 further reacts with Mg(NH2)2 to form LiMgBN3H3. LiMgBN3H3 subsequently interacts with additional 2 equivalents of LiH to form Li3BN2 and MgNH as well as hydrogen. 相似文献
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A. Abdelkader H. Daly Y. Saih K. Morgan M.A. Mohamed S.A. Halawy C. Hardacre 《International Journal of Hydrogen Energy》2013
Co3O4, Fe2O3 and a mixture of the two oxides Co–Fe (molar ratio of Co3O4/Fe2O3 = 0.67 and atomic ratio of Co/Fe = 1) were prepared by the calcination of cobalt oxalate and/or iron oxalate salts at 500 °C for 2 h in static air using water as a solvent/dispersing agent. The catalysts were studied in the steam reforming of ethanol to investigate the effect of the partial substitution of Co3O4 with Fe2O3 on the catalytic behaviour. The reforming activity over Fe2O3, while initially high, underwent fast deactivation. In comparison, over the Co–Fe catalyst both the H2 yield and stability were higher than that found over the pure Co3O4 or Fe2O3 catalysts. DRIFTS-MS studies under the reaction feed highlighted that the Co–Fe catalyst had increased amounts of adsorbed OH/water; similar to Fe2O3. Increasing the amount of reactive species (water/OH species) adsorbed on the Co–Fe catalyst surface is proposed to facilitate the steam reforming reaction rather than decomposition reactions reducing by-product formation and providing a higher H2 yield. 相似文献
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Junliang Li Shaorong Wang Zhengrong WangRenzhu Liu Tinglian WenZhaoyin Wen 《Journal of power sources》2008
(La0.74Bi0.10Sr0.16)MnO3−δ (LBSM)–(Bi2O3)0.7(Er2O3)0.3(ESB) composite cathodes were fabricated for intermediate-temperature solid oxide fuel cells with Sc-stabilized zirconia as the electrolyte. The performance of these cathodes was investigated at temperatures below 750 °C by AC impedance spectroscopy and the results indicated that LBSM–ESB had a better performance than traditional composite electrodes such as LSM–GDC and LSM–YSZ. At 750 °C, the lowest interfacial polarization resistance was only 0.11 Ω cm2 for the LBSM–ESB cathode, 0.49 Ω cm2 for the LSM–GDC cathode, and 1.31 Ω cm2 for the LSM–YSZ cathode. The performance of the cathode was improved gradually by increasing the ESB content, and the performance was optimal when the amounts of LBSM and ESB were equal in composite cathodes. This study shows that the sintering temperature of the cathode affected performance, and the optimum sintering temperature for LBSM–ESB was 900 °C. 相似文献
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Nawadee Srisiriwat Supaporn Therdthianwong Apichai Therdthianwong 《International Journal of Hydrogen Energy》2009
Oxidative steam reforming of ethanol at low oxygen to ethanol ratios was investigated over nickel catalysts on Al2O3 supports that were either unpromoted or promoted with CeO2, ZrO2 and CeO2–ZrO2. The promoted catalysts showed greater activity and a higher hydrogen yield than the unpromoted catalyst. The characterization of the Ni-based catalysts promoted with CeO2 and/or ZrO2 showed that the variations induced in the Al2O3 by the addition of CeO2 and/or ZrO2 alter the catalyst's properties by enhancing Ni dispersion and reducing Ni particle size. The promoters, especially CeO2–ZrO2, improved catalytic activity by increasing the H2 yield and the CO2/CO and the H2/CO values while decreasing coke formation. This results from the addition of ZrO2 into CeO2. This promoter highlights the advantages of oxygen storage capacity and of mobile oxygen vacancies that increase the number of surface oxygen species. The addition of oxygen facilitates the reaction by regenerating the surface oxygenation of the promoters and by oxidizing surface carbon species and carbon-containing products. 相似文献
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Madhu Chennabasappa Brandon Kelly Dominik Bender Josh Garrett Manivannan Venkatesan 《International Journal of Hydrogen Energy》2018,43(8):4101-4107
Composite ceramic cathodes represented by the formula (1-x-y) LiNi1/3Co1/3Mn1/3O2·xLi2MnO3·yLiCoO2 were studied. A ternary compositional diagram was built with these ceramic materials as end-members, and selected points were chosen to represent the compositional space. Synthesized ceramic composite materials were investigated as to whether integration of structurally compatible units leads to improved electrochemical performance. Detailed structural (X-ray diffraction – XRD), elemental (X-ray photoelectron spectroscopy-XPS), microstructure (Scanning electron microscopy – SEM), and electrochemical (galvanostatic testing of half-cells) studies were performed and are presented. Within eight samples studied three compositions are found to exhibit first discharge capacity of around 230 mAh/g. 相似文献
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Pristine Ni/γ–Al2O3 and CeO2–Ni/γ–Al2O3 catalysts were prepared by co-impregnation technique for dry reforming of propane. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to examine the structure and morphology of the catalysts before and after the reforming reactions. The excellent interaction between catalyst active phases was observed in both CeO2–Ni/γ–Al2O3 and Ni/γ–Al2O3 stabilized with polyethelene glycol (Ni/γ–Al2O3–PEG). Towards C3H8 and CO2 conversion, the CeO2–Ni/γ–Al2O3 and Ni/γ–Al2O3–PEG showed improved catalytic activity when compared to the pristine Ni/γ–Al2O3 catalyst. Interestingly, high H2 concentration was achieved with the CeO2–Ni/γ–Al2O3 and high CO concentration with the Ni/γ–Al2O3–PEG, which is due to the nanoconfinement of nickel particles within the support and favorable metal-support interaction as a result of plasma reduction. The CeO2–Ni/γ–Al2O3 catalyst exhibited better stability for anti-sintering and coke resistance, thus exhibiting high reactivity and durability in the dry reforming. 相似文献
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Yucun Zhou Zhencheng Zhang Chun Yuan Junliang Li Changrong Xia Zhongliang Zhan Shaorong Wang 《International Journal of Hydrogen Energy》2013
Metal-supported solid oxide fuel cells (SOFCs) containing porous 430L stainless steel support, Ni-YSZ anode and YSZ electrolyte were fabricated by tape casting, laminating and co-firing in a reduced atmosphere. (Bi2O3)0.7(Er2O3)0.3–Ag composite cathode was applied by screen printing and in-situ sintering. The polarization resistances of the composite cathode were 1.18, 0.48, 0.18, 0.09 Ω cm2 at 600, 650, 700 and 750 °C, respectively. A promissing maximum power density of 568 mW cm−2 at 750 °C was obtained of the single cell. Short-term stability was measured as well. 相似文献
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The organic-inorganic composite g-C3N4–SrTiO3:Rh was prepared for the first time as a photocatalyst for hydrogen production and the resulting hydrogen evolution rate under visible light irradiation from aqueous methanol solution was measured. A high hydrogen evolution rate of 223.3 μmol h−1 was achieved by using 0.1 g of as-prepared photocatalyst powder comprised of 20 wt.% g-C3N4 80 wt.% SrTiO3:Rh (0.3 mol%). The hydrogen evolution rate was greater than that obtained by SrTiO3:Rh (0.3 mol%) by a factor of 3.24. The quantum efficiency of as-prepared composite photocatalyst was 5.5% at 410 nm for hydrogen evolution. The high activity of the composite photocatalyst for hydrogen evolution stemmed from its electron–hole separation and transportation capabilities due to the hetero-junctions of the organic-inorganic composite materials. The proposed mechanism for the electron–hole separation and hydrogen evolution of the g-C3N4–SrTiO3:Rh composite under visible light irradiation featured the reduced recombination of the photo-generated charge carriers. The doping of Rh ions into the SrTiO3 has contributed to the high photocatalytic activity by forming a donor level from the valance band to the conduction band. 相似文献
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具有三维网络结构的NASICON型Na3V2(PO4)3材料,由于其稳定的电压平台,较高的理论容量(117 mA·h/g),被视为一种具有良好应用前景的钠离子电池负极材料。采用溶剂热和进一步热处理的方式,获得石墨烯包封Na3V2(PO4)3的复合材料[Na3V2(PO4)3/G],有效提高了Na3V2(PO4)3的电子导电性。在0.01~3.00 V电压区间,0.2 C倍率进行测试时,Na3V2(PO4)3/G复合材料在230圈循环后,其放电比容量保持在100.9 mA·h/g,容量保持率高达68.4%,即使在5 C倍率,其放电比容量仍可达65.2 mA... 相似文献
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Shu-Sheng Liu Li-Xian Sun Jian Zhang Yao Zhang Fen Xu Yong-Heng Xing Fen Li Jijun Zhao Yong Du Wang-Yu Hu Hui-Qiu Deng 《International Journal of Hydrogen Energy》2010
To improve the dehydrogenation properties of MgH2, a novel hydrogen storage system, MgH2–Li3AlH6, is prepared by mechanochemical milling. Three physical mixtures containing different mole ratios (1:4, 1:1 and 4:1) of MgH2 and Li3AlH6 are studied and there exists a mutual destabilization effect between the components. The last mixture shows a capacity of 6.5 wt% H2 with the lowest starting temperature of dehydrogenation (170 °C). First, Li3AlH6 decomposes into Al, LiH and H2, and then the as-formed Al can easily destabilize MgH2 to form the intermetallic compound Mg17Al12 at a temperature of 235 °C, which is about 180 °C lower than the decomposition temperature of pristine MgH2. Finally, the residual MgH2 undergoes a self-decomposition whose apparent activation energy has been reduced by about 22 kJ mol−1 compared with pristine MgH2. At a constant temperature of 250 °C, the mixture can dehydrogenate completely under an initial vacuum and rehydrogenate to form MgH2 under 2 MPa H2, showing good cycle stability after the first cycle with a capacity of 4.5 wt% H2. The comparison between 4 MgH2 + Li3AlH6 and 4 MgH2 + LiAlH4 mixtures is also investigated. 相似文献
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Porous composite cathodes including (La0.74Bi0.10Sr0.16)MnO3−δ (LBSM) and Bi1.4Er0.6O3 (ESB) were fabricated and characterized using AC impedance spectroscopy. In our earlier work, the growth and aggregation of ESB particles were found in LBSM–ESB composite cathodes. In this study, therefore, two approaches were used to restrain the growth and aggregation of ESB particles. First, the sintering temperature of the composite cathode was reduced by introducing a sintering function layer, which caused a 22% reduction in the initial polarization resistance (R), but the cathode polarization resistance decreased at a rate of 2.15 × 10−4 Ω cm2 h−1 at 700 °C during a period of 100 h. Second, nano-sized Gd-doped ceria powder (CGO) was added to the composite cathode system. Stability improvement was achieved at 10 vol% CGO, and the degradation rate at 700 °C was 4.01 × 10−5 Ω cm2 h−1 during a period of 100 h. 相似文献
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Peng Xiao Xiaoming Ge Lan Zhang Jong-Min Lee Jing-Yuan Wang Xin Wang 《International Journal of Hydrogen Energy》2012
Strontium molybdate (SrMoO3) as an electronic conductor was incorporated with yttria-stabilized zirconia (YSZ) to form an anode scaffold for solid oxide fuel cells. Gd0.2Ce0.8O1.9 (GDC) nanoparticles were introduced by wet impregnation to complete the Ni-free GDC infiltrated SrMoO3–YSZ anode fabrication. The effects of SrMoO3 on the electrode conductivity and GDC infiltration on the catalytic activity were examined. A pronounced performance improvement was observed both on wet H2 and CH4 oxidation for the 56 wt.% GDC infiltrated SrMoO3–YSZ. In particular, the polarization resistance decreased from 8 Ω cm2 to 0.5 Ω cm2 under wet H2 (3% H2O) at 800 °C with the introduction of GDC. Under wet CH4 at 900 °C, a maximum power density of 160 mW cm−2 was obtained and no carbon deposition was observed on the anode. It was found that the addition of H2O in the anode caused an increase of electrode ohmic resistance and a decrease of open circuit voltage. Redox cycling stability was investigated and only a slight drop in cell performance was observed after 5 cycles. These results suggest that GDC infiltrated SrMoO3–YSZ is a promising anode material for solid oxide fuel cells. 相似文献
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Thermal behaviors and stability of glass/glass–ceramic-based sealant materials are critical issues for high temperature solid oxide fuel/electrolyzer cells. To understand the thermophysical properties and devitrification behavior of SrO–La2O3–Al2O3–B2O3–SiO2 system, glasses were synthesized by quenching (25 − X)SrO–20La2O3–(7 + X)Al2O3–40B2O3–8SiO2 oxides, where X was varied from 0.0 mol% to 10.0 mol% at 2.5 mol% interval. Thermal properties were characterized by dilatometry and differential scanning calorimetry (DSC). Microstructural studies were performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). All the compositions have a glass transition temperature greater than 620 °C and a crystallization temperature greater than 826 °C. Also, all the glasses have a coefficient of thermal expansion (CTE) between 9.0 × 10−6 K−1 and 14.5 × 106 K−1 after the first thermal cycle. La2O3 and B2O3 contribute to glass devitrification by forming crystalline LaBO3. Al2O3 stabilizes the glasses by suppressing devitrification. Significant improvement in devitrification resistance is observed as X increases from 0.0 mol% to 10.0 mol%. 相似文献