共查询到20条相似文献,搜索用时 62 毫秒
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采用浸渍法与化学还原法相结合制备了一系列USY型分子筛负载非晶态合金硼化钴(CoB/USY)催化剂,并系统探究了该催化剂在催化硼氢化钠水解制氢中的催化活性。 XRD表征表明,USY分子筛载体上负载的活性组分CoB属于非晶态结构。 通过扫描电子显微镜,对比了负载型CoB/USY催化剂和粉末状CoB催化剂的微观形貌,发现非晶态合金活性组分CoB能够很好的分布在USY分子筛载体表面,较粉末状CoB有更高的分散度。 催化硼氢化钠水解制氢实验结果表明,相对于粉末状CoB催化剂,负载型CoB/USY催化剂在硼氢化钠水解制氢中具有更高的催化活性,30 ℃时NaBH4水解产氢速率约为1.5 L/(min·g)。 反应动力学的计算结果显示,负载型CoB/USY催化剂在催化NaBH4水解制氢反应中表观活化能约为65.9 kJ/mol,大大低于粉末状CoB催化剂的活化能(72.1 kJ/mol)。 相似文献
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泡沫镍载钌催化硼氢化钠水解制氢 总被引:1,自引:0,他引:1
应用化学镀法制备泡沫镍载钌(Ru)催化剂,以其用于燃料电池硼氢化钠(NaBH4)水解即时供氢.该催化剂具有稳定高效的活性和稳定性能,而泡沫镍的预处理是一重要步骤.研究了制氢过程中NaBH4浓度、反应温度及使用次数对产氢速率的影响.结果表明:产氢速率随温度的升高快速上升,当反应温度从15℃升高到60℃,产氢速率增加了十几倍;在NaBH4浓度为20%的3%NaOH溶液中,使用载Ru量为3%的催化剂,于23.5℃常压下,水解NaBH4,其产氢速率达到0.784 mL.s-1.g-1.这种容易制备的催化剂在多次使用后仍显示出较高的活性. 相似文献
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硼氢化钠水解制氢的研究 总被引:8,自引:0,他引:8
采用置换镀的方法在泡沫镍基体上获得不同载钌量的NaBH4水解制氢催化剂。实验结果表明,NaBH4水解制氢反应为零级反应,氢气生成速率随载钌量的增加而变快;当泡沫镍表面完全被钌覆盖时,载钌量为6%,相应的催化能力最强。与离子交换树脂载钌催化剂相比,泡沫镍载钌催化剂更稳定、耐用。实验还证实,30%比35%的NaBH4水溶液在相同的催化剂作用下更易发生水解反应;NaBH4水溶液中加入少量的NaOH有助于提高钌催化剂的催化性能。通过对NaBH4储氢体系的能量计算,说明采用该氢源体系的微型燃料电池的能量密度有望达到甚至超过锂离子电池的比能量水平。 相似文献
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当前,化石燃料的大量消耗和对能源日益增长的需求推动了可再生和高效能源材料的开发。氢因丰富的来源以及清洁的特性而被视为潜在的能源载体。通过水解氨硼烷制备清洁可再生的氢气是解决能源问题的有效途径之一。开发高效安全的催化剂一直是该领域研究的重点和热点。金属-有机骨架材料(MOFs)因其独特的结构、组成和特性,在氨硼烷水解制氢中有广泛的应用。本文以MOFs材料在催化剂设计制备中的作用为侧重点,综述了不同MOFs材料在催化氨硼烷水解制氢反应中的作用,对其在催化氨硼烷水解制氢应用过程中所存在的问题和今后的发展进行了总结和展望。 相似文献
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氢气作为全球公认的清洁能源载体,备受关注。寻找安全高效的储氢材料以转型到氢能社会是当前氢能应用面临最大的挑战之一。氨硼烷(NH3BH3,AB)具有非常高的储氢质量分数(19.6 wt%)和体积储氢密度(0.145 kgH2/L),因其在储氢和放氢性能方面的显著优势,被认为是一种颇具应用潜力的化学储氢材料。氨硼烷能够通过热解、醇解和水解放出氢气。其中,氨硼烷水解制氢可以通过催化剂进行可控放氢,且具有反应条件温和、不产生CO(易使催化剂中毒)等优点,被认为是一种安全高效和实用性强的制氢技术。本文简要介绍了氨硼烷的性质和合成,阐述了氨硼烷水解制氢的机理,综述了近年来氨硼烷水解制氢催化剂的研究进展,分析了碱对氨硼烷水解制氢的促进作用,并讨论了水解产物回收利用问题。 相似文献
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超临界水气化有机物制氢研究 总被引:2,自引:0,他引:2
针对一些有机物的超临界水气化(SCWG)制氢过程,分别概述了模型有机物如葡萄糖、甲醇、纤维素、木质素和真实生物质及有机废物/水的影响因素、中间产物及反应路径;分析了均相催化剂如碱、碱金属盐和非均相催化剂如ZrO2、活性碳、贵金属、过渡金属的催化气化效率及催化机理,并指出非均相催化SCWG过程是SCWG技术的重要发展方向;对SCWG制氢过程热力学进行初步的讨论;简要介绍了目前世界上的3套SCWG制氢中试装置的运行情况,提出SCWG过程工业化应用的难点及未来技术的发展方向。 相似文献
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将PdAg纳米颗粒负载到MIL-101(Fe)上作为硼氢化钠水解制氢的催化剂。采用XRD、TEM、HRTEM、XPS、SEM和EDS等方法对催化剂PdAg/MIL-101(Fe)的结构进行了表征。PdAg/MIL-101(Fe)在硼氢化钠水解制氢中表现出较高的催化活性,在温和的条件下水解制氢最大速率为2.60 L·min–1·gcat.–1。详细研究了反应温度、催化剂用量、氢氧化钠和硼氢化钠浓度对该催化反应的影响规律。结果发现,制氢速率很大程度上依赖于反应温度,随着反应温度的升高,制氢速率明显增加,制氢的表观活化能为54.89 kJ·mol–1。该催化剂重用性能好,5次循环后仍能保持活性。 相似文献
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Vasudeva Rao Bakuru Marilyn Esclance DMello Prof. Dr. Suresh Babu Kalidindi 《Chemphyschem》2019,20(10):1177-1215
Hydrogen is in limelight as an environmental benign alternative to fossil fuels from few decades. To bring the concept of hydrogen economy from academic labs to real world certain challenges need to be addressed in the areas of hydrogen production, storage, and its use in fuel cells. Crystalline metal-organic frameworks (MOFs) with unprecedented surface areas are considered as potential materials for addressing the challenges in each of these three areas. MOFs combine the diverse chemistry of molecular linkers with their ability to coordinate to metal ions and clusters. The unabated flurry of research using MOFs in the context of hydrogen energy related activities in the past decade demonstrates the versatility of this class of materials. In the present review, we discuss major strategical advances that have taken place in the field of “hydrogen economy and MOFs” and point out issues requiring further attention. 相似文献
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A. Venkataraman 《Journal of Thermal Analysis and Calorimetry》1996,46(1):219-224
Thermal techniques viz., TG/DTA/DSC methods have been employed in understanding the formation and decomposition of hydrogen ferrite phase (H-F) as a metastable intermediate in the conversion of -Fe2O3·xH2O, to -Fe2O3. Magnetic hysteresis measurements carried out at liquid N2 and at room temperature for the vacancy ordered -Fe2O3 and its H-F phase also supplement these studies.The author thanks prof. M.R. Udpa, IIT, Madras for supplying TG/DTA data on Stanton Redcroft Instrument and to the Head, Department of Chemistry, S.P. University, Vallabh Vidyanagar for providing the facilities. 相似文献
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Kevin Bläsing Dr. Jonas Bresien René Labbow Prof. Dr. Axel Schulz Dr. Alexander Villinger 《Angewandte Chemie (International ed. in English)》2018,57(29):9170-9175
A highly labile dimer of hydrogen cyanide, HCN???HCN, was extracted from liquid HCN by adduct formation with the bulky Lewis acid B(C6F5)3, affording HCN???HCN?B(C6F5)3, which was fully characterized. The influence of the solvent (HCN, CH2Cl2, and aromatic hydrocarbons) on the crystallization process was studied, revealing dimer formation when using HCN or CH2Cl2 as solvent, whereas aromatic hydrocarbons led to the formation of monomeric arene??HCN?B(C6F5)3 adducts, additionally stabilized by η6‐coordination of the aromatic ring system similar to well‐known half‐sandwich complexes. 相似文献
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催化剂Ni/Y2O3上低温乙醇水蒸气重整制氢研究——氢气预还原对催化剂性能的影响 总被引:5,自引:3,他引:5
用浸渍-热分解-氢还原法(IHDHR)和浸渍-热分解法(IHD)分别制备了两种纳米尺寸的Ni/Y2O3催化剂,并应用X-光电子能谱、X-射线衍射、BET比表面测试等分析技术对两种催化剂的结构进行了表征和比较。采用固定床反应器对两种催化剂的催化性能进行实验测试。结果表明,氢气预还原与否对该纳米Ni/Y2O3催化剂的催化性能有一定的影响,经过氢气预还原的催化剂对低温乙醇水蒸气重整反应表现出较高的活性和稳定性,250?℃时,乙醇的转化率达到81.9%;320 ℃时,乙醇的转化率达到95.3%,对氢气的选择性为53.6%。对经过氢预还原的Ni/Y2O3催化剂进行了60 h的稳定性测试。 相似文献
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Davi Fernando BackManfredo Hörner Fernanda BrochGelson Manzoni de Oliveira 《Polyhedron》2012,31(1):558-564
The new ligand 1,3-bis(3-methoxy-4-methylbenzoate) triazene (1, bmmbt), and the already known ligand 1,3-bis(4-acetylphenyl)triazene (bapht), yield the two new palladium(II) complexes [(bmmbt)Pd(PPh3)2Cl]·DMSO (2) and [(bapht)Pd(PPh3)2Cl] (3) (Ph = phenyl; DMSO = dimethylsulfoxide). Compound 1 shows the existence of more than one interaction promoting the coupling between the triazene chains. Other remarkable types of interactions in 1 are bifurcated hydrogen contacts and non-classical CH···π bonding. Complexes 2 and 3 present a planar geometry, supported also through bifurcated intramolecular Cl···H-C interactions, as well as the occurrence of trifurcated Cl···H-C intermolecular interactions. 相似文献
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In this work, the excited-state hydrogen bonding dynamics of photoexcited coumarin 102 in aqueous solvent is reconsidered. The electronically excited states of the hydrogen bonded complexes formed by coumarin 102 (C102) chromophore and the hydrogen donating water solvent have been investigated using the time-dependent density functional theory method. Two intermolecular hydrogen bonds between C102 and water molecules are considered. The previous works (Wells et al., J Phys Chem A 2008, 112, 2511) have proposed that one intermolecular hydrogen bond would be strengthened and the other one would be cleaved upon photoexcitation to the electronically excited states. However, our theoretical calculations have demonstrated that both the two intermolecular hydrogen bonds between C102 solute and H(2)O solvent molecules are significantly strengthened in electronically excited states by comparison with those in ground state. Hence, we have confirmed again that intermolecular hydrogen bonds between C102 chromophore and aqueous solvents are strengthened not cleaved upon electronic excitation, which is in accordance with Zhao's works. 相似文献
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《Acta Crystallographica. Section C, Structural Chemistry》2017,73(10):814-819
The synthesis, 1H and 13C NMR spectra, and X‐ray structures are described for three dialkoxy ethynylnitrobenzenes that differ only in the length of the alkoxy chain, namely 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene, C14H17NO4, 1,2‐dibutoxy‐4‐ethynyl‐5‐nitrobenzene, C16H21NO4, and 1‐ethynyl‐2‐nitro‐4,5‐dipentoxybenzene, C18H25NO4. Despite the subtle changes in molecular structure, the crystal structures of the three compounds display great diversity. Thus, 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene crystallizes in the trigonal crystal system in the space group , with Z = 18, 1,2‐dibutoxy‐4‐ethynyl‐5‐nitrobenzene crystallizes in the monoclinic crystal system in the space group P 21/c , with Z = 4, and 1‐ethynyl‐2‐nitro‐4,5‐dipentoxybenzene crystallizes in the triclinic crystal system in the space group , with Z = 2. The crystal structure of 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene is dominated by planar hexamers formed by a bifurcated alkoxy sp‐C—H…O,O′ interaction, while the structure of the dibutoxy analogue is dominated by planar ribbons of molecules linked by a similar bifurcated alkoxy sp‐C—H…O,O′ interaction. In contrast, the dipentoxy analogue forms ribbons of molecules alternately connected by a self‐complementary sp‐C—H…O2N interaction and a self‐complementary sp2‐C—H…O2N interaction. Disordered solvent was included in the crystals of 1‐ethynyl‐2‐nitro‐4,5‐dipropoxybenzene and its contribution was removed during refinement. 相似文献