氢气储存材料

介绍制氢方法及当前国内外储氢材料的最新研究进展,重点阐述镁基合金材料、氢化物储氢材料和有机储氢材料的储氢性能及评价,并预测了各种储氢材料的发展前景.     

高密度储氢材料的研究进展

氢是一种清洁的燃料,氢能被公认为人类未来的理想能源,而氢能的利用最关键的环节就是氢能的储存。氢的储存是氢能现阶段开发和利用的瓶颈。氢的储存方法有高压气态储存、低温液态储存和固态储存等3种,其中高压气态储存或低温液态储存不能满足将来的储氢目标。固态储氢是通过化学或物理吸附将氢气储存于固态材料中,其能量密度高且安全性好,被认为是最有发展前景的一种氢气储存方式。目前该领域的研究取得了一些阶段性的成果,虽然目前发展的各种材料都有不易克服的缺点,但储氢材料的前景还是十分广阔的。高密度储氢材料由轻元素构成,包括铝氢化物、硼氢化物、氨基氢化物、氨硼烷等,理论储氢质量分数均达到5%以上。简述了氢能的优势及储存方法,介绍了镁基储氢材料、络合物储氢材料、Li-B-H系和2种或2种以上储氢材料复合4类有望实用化的储氢材料的研究现状,并指出了储氢材料的发展方向。     

储氢合金的研究进展

储氢合金是近年来开发的一类新型高性能材料。本文介绍了储氢合金的工作原理、基本类型、性能及开发的最新进展 ,讨论了它在氢的储存、运输、净化、催化和镍。氢化物电池等高技术领域中的应用前景     

球磨时间对TiZr氢化物掺杂NaAlH4储放氢性能的影响

采用XRD、Sievert等容法储放氢性能测试、SEM等分析手段,研究了球磨工艺对TiZrH1.7～1.9氢化物掺杂NaAlH4材料的形态、物相及可逆储放氢性能的影响.研究结果表明:TiZrH1.7～1.9氢化物掺杂NaA1H4可以实现可逆吸放氢,其中球磨10 h的复合储氢材料在160℃、0.1 MPa放氢条件下,总放氢量(质量分数)达4.5%,40 min可逆放氢量超过3.0%,显示了良好的储放氢动力学性能;TiZrH1.7～1.9氢化物在复合储氢材料吸放氢前后保持物相和结构不变,对NaAlH4配位氢化物的可逆储放氢反应起到了催化改善作用.     

铝氢化钠储氢性能及其改进方法研究进展

配位氢化物NaAlH₄具有较高的储氢密度且生产成本低廉,是一种典型的储氢材料;然而,较高的脱氢温度、较慢的氢吸放速率及较差的可逆性限制了其实际应用。作为一种很有前途的车载储氢介质,其储氢性能的改性研究长期备受关注。论述了NaAlH₄储氢性能及其改进方法,阐明了添加催化剂和结构纳米化2种基本改进方法的原理,也阐述了理论模拟在研究NaAlH₄储氢性能中的重要促进作用。     

金属氢化物导热系数测量

储氢材料是一类新的功能材料.研究它的导热性能,对于储氢材料使用时放氢所需的热源以及加热时间是十分重要的.通过稳态测量和非稳态测量理论分析,设计出相应的实验装置,探讨金属氢化物导热系数的测定.     

FeCl2掺杂对LiBH4-LiAlH4体系放氢动力学性能的影响

为提高LiBH 4 的放氢动力学性能，研究了LiBH 4 -LiA1H 4 混合金属氢化物体系及FeCl 2 掺杂对其储氢性能的影响，相关因素包括FeCl 2 比例、球磨时间等.研究表明,2 mol% FeCl 2 掺杂的2LiBH 4 -LiAlH 4 样品在450 ℃恒温状态下能放出8.25wt%的氢气，且放氢动力学性能得到显著的改善；在混合氢化物体系中LiAlH 4 和FeCl 2 相互协同，共同作用改善LiBH 4 的储氢性能.     

储氢合金

最近,日本使用了储氢合金.储氢合金在温度下降而加压时就会吸入氢气形成金属氢化物,同时产生热量.相反,在温度升高并减压时,又还原为金属和氢气,同时吸热.属于这类合金的有铁钛系、镧镍系、钛锰系、混合稀土类合金等.     

替代元素对储氢合金ZrMn2电子结构的影响

利用电荷离散变分Xα(SCC-DV-Xα)方法计算ZrMnM(M=Mn、Co、V、Fe)及其氢化物的电子结构，分析替代元素M电子结构变化对吸氢性能的影响。结果表明，替代元素M的3d电子变化是影响ZrMnM合金储氢性能的主要原因之一，替代元素3p轨道的电荷占据数可作为比较ZrMnM氢化物稳定性的依据。     

A2B型Ti2Ni基储氢合金研究进展

质量轻、储量大、清洁的氢是未来一种比较理想的能源载体.而氢的安全、高效存储是实现氢应用的关键问题之一.作为一种储氢材料的储氢合金一直是储氢研究的热点之一.其中,A2B型Ti2Ni基储氢合金具有较大的理论储氢容量(约500mAh/g),受到广泛的关注.介绍了晶态Ti2Ni合金的结构特性,概述了Ti2Ni基储氢合金的研究进展,并提出了相关研究中存在的问题及今后发展的研究方向.     

Hydrogen——A sustainable energy carrier

Hydrogen may play a key role in a future sustainable energy system as a carrier of renewable energy to replace hydrocarbons. This review describes the fundamental physical and chemical properties of hydrogen and basic theories of hydrogen sorption reactions, followed by the emphasis on state-of-the-art of the hydrogen storage properties of selected interstitial metallic hydrides and magnesium hydride, especially for stationary energy storage related utilizations. Finally, new perspectives for utilization of metal hydrides in other applications will be reviewed.     

The use of metal hydrides in fuel cell applications

This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field, as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells.The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H_2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H_2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally, the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.     

Materials design and modification on amide-based composites for hydrogen storage

Amide-based composite system has the potential to meet the needs of onboard hydrogen storage for fuel cell vehicles due to its relatively high hydrogen capacity and tunable thermodynamics. A large number of amide–hydride and amide–complex hydride composites have been developed in the past decades. This article reviews the state-of-the-arts of amide–hydride composite systems with the focus on the materials design and modification.     

Significantly enhanced hydrogen desorption properties of Mg(AlH4)2 nanoparticles synthesized using solvent free strategy

Mg(AlH_4)_2 nanoparticles with a particle size less than 10 nm have been successfully synthesized by mechanochemical method using LiAlH_4 and MgCl_2 as raw materials together with Li Cl buffering additive. In comparison to Mg(AlH_4)_2 microparticles, Mg(AlH_4)_2 nanoparticles exhibit a faster hydrogen desorption kinetics and lower desorption temperature. The hydrogen desorption temperatures of the first and second dehydrogenation steps are 80 and 220 °C for the Mg(AlH_4)_2 nanoparticles, which are about 65 and 60 °C, respectively, lower than those of Mg(AlH_4)_2 microparticles. The decomposition activation energy is reduced from 135 k J/mol for Mg(AlH_4)_2 microparticles to 105.3 k J/mol for Mg(AlH_4)_2 nanoparticles. It is proposed that the shortened diffusion distance and enhanced diffusivity of Mg(AlH_4)_2/MgH_2 nanoparticles provide an energy destabilization for lowering the dehydrogenation temperature, and thus being the key factor for promoting the hydrogen desorption kinetics. More importantly, it is demonstrated that the dehydrided nano MgH_2 hydride with a particle size below 10 nm can be formed after rehydrogenation process, resulting in the good cycling hydrogen desorption performance of nano MgH_2.     

Facile synthesis of nanosized sodium magnesium hydride, NaMgH3

The ternary magnesium hydride NaMgH 3 has been synthesised via reactive milling techniques.The method employed neither a reactive H2 atmosphere nor high pressure sintering or other post-treatment processes.The formation of the ternary hydride was studied as a function of milling time and ball:powder ratio.High purity NaMgH 3 powder(orthorhombic space group Pnma,a 5.437(2),b 7.705(5),c 5.477(2) ;Z 4) was prepared in 5 h at high ball:powder ratios and characterised by powder X-ray diffraction(PXD),Raman spectroscopy and scanning electron microscopy/energy dispersive X-ray spectroscopy(SEM/EDX).The products formed sub-micron scale(typically 200-400 nm in size) crystallites that were approximately isotropic in shape.The dehydrogenation behaviour of the ternary hydride was investigated by temperature programmed desorption(TPD).The nanostructured hydride releases hydrogen in two steps with an onset temperature for the first step of 513 K.     

Recent advances in additive-enhanced magnesium hydride for hydrogen storage

The discovery of new hydrogen storage materials has greatly driven the entire hydrogen storage technology forward in the past decades. Magnesium hydride, which has a high hydrogen capacity and low cost, has been considered as one of the most promising candidates for hydrogen storage. Unfortunately, extensive efforts are still needed to better improve its hydrogen storage performance, since MgH2 suffers from high operation temperature, poor dehydrogenation kinetic, and unsatisfactory thermal management. In this paper, we present an overview of recent progress in improving the hydrogenation/de-hydrogenation performance of MgH2, with special emphases on the additive-enhanced MgH2 composites. Other widely used strategies (e. g. alloying, nanoscaling, nanoconfinement) in tuning the kinetics and thermodynamics of MgH2 are also presented. A realistic perspective regarding to the challenges and opportunities for further researches in MgH2 is proposed.     

Nanomaterials for renewable hydrogen production, storage and utilization

An ever growing demand for energy coupled with increasing pollution is forcing us to seek environmentally clean alternative energy resources to substitute fossil fuels. The rapid development of nanomaterials has opened up new avenues for the conversion and utilization of renewable energy. This article reviews nanostructured materials designed for selected applications in renewable energy conversion and utilization. The review is based on the authors’ research, with particular focus on solar hydrogen production, hydrogen storage and hydrogen utilization. The topics include photoelectrochemical (PEC) water splitting and photocatalytic hydrogen production, solid-state hydrogen storage, and proton exchange membrane fuel cells (PEMFCs). It is expected that the rational design of nanomaterials could play an important role in achieving a renewable energy based economy in the coming decades.     

Hydrogen storage performance of LaNi3.95Al0.75Co0.3 alloy with different preparation methods

Rare-earth AB₅-type La–Ni–Al hydrogen storage alloys are widely studied due to their extensive application potentials in hydrogen isotope storage, hydrogen isotope isolation and hydrogen compressors, etc. Good hydriding/dehydriding kinetics, easily activation, high reversibility are important factors for their practical application. However, their overall hydrogen storage performance, especially plateau pressure and hydrogen absorption/desorption durability need to be further optimized. In this study, the microstructures and the hydrogen storage properties of as-cast, annealed, and melt-spun LaNi_3.95Al_0.75Co_0.3 alloys were investigated. The experimental results of XRD and SEM showed that all alloys contained a pure CaCu₅ type hexagonal structure LaNi₄Al phase. The cell volume increased in an order of annealed ?> ?melt-spun ?> ?as-cast, resulting in a lower hydrogen absorption/desorption plateau pressure and a more stable hydride phase. The hydrogen storage capacity of three alloys was almost the same. The slope factor of the annealed and melt-spun alloys is smaller than the as-cast alloy, indicating that heat-treatment process can make the alloys more uniform. For the cycle stability of the alloys, the hydrogen absorption rate of the annealed alloy and melt-spun alloy was much faster than that of the as-cast alloy after 500 cycles. The melt-spun alloy showed high pulverization resistance during hydrogen absorption/desorption, and exhibited an excellent cycling retention of 99% after 500 cycles, suggesting that melt-spinning process can enhance the cycle stability and improve the cycle life of the alloy.     

混氢天然气物性规律及管道水合物生成模拟分析

氢能是一种绿色低碳的二次能源,在天然气管道中掺入氢气进行大规模运输是当前研究的热门领域。但氢气与天然气混合后因其物性参数的改变,使管道产生堵塞、氢脆、泄漏、聚积、燃烧和爆炸等问题。基于此,利用Aspen HYSYS软件,选取代表性数据,运用理论研究、数据模拟和数据分析等方法,针对不同混氢比下天然气与氢气混合后的物性变化规律和管道水合物生成情况进行模拟分析。结果表明：随着混氢比增大,混合气体温度先降低再升高,在混氢比为36%时达到最低温度;混合后气体质量密度和比热容比与混氢比呈负相关;质量焓、质量熵、质量基准热值、Z因子、热导率、运动黏度均与混氢比成正相关;随着混氢比增大,水合物生成温度降低,压力升高。可见在天然气管道中适当混入少量氢气可抑制水合物的生成;混氢天然气物性参数变化规律为探究适合不同条件下的最优混氢比、保证管道输送及使用的安全性提供了数据基础。     

MgH2-X(X=Si,Ge,Sn,Pb)体系解氢能力的第一原理计算

采用基于密度泛函理论的第一原理赝势平面波方法,研究了MgH2-X(X=Si,Ge,Sn,Pb)合金化体系的能量、几何与电子结构.负形成热的计算发现:合金化元素X在镁氢化合物(MgH2)中少量固溶时,体系相结构稳定性变差,预示着解氢能力得到改善.电子态密度(DOS)与电子密度的进一步分析发现:镁氢化合物X合金化后,X与其周围的H原子相互作用不明显,而Mg-H之间的成键作用减弱.体系Ge合金化解氢能力增强的理论计算与实验结果一致,预测Si,Sn,Pb少量固溶于MgH2能提高体系的解氢能力.