金属-氮-氢体系储氢材料

氢能作为未来理想的清洁能源之一,已经成为全球研究的重要领域,而在氢能的应用中最关键的问题是氢气的存储.近年来,人们的研究集中在固态储氢材料上,许多新型储氢材料不断出现,其中由轻元素组成的金属-氮-氢体系拥有储氢容量高、可逆性好等优点,被认为是最有前景的储氢材料之一.目前金属-氮-氢体系已经发展出许多体系,而研究最多的是Li-N-H和Li-Mg-N-H两种体系.本文重点综述了两者作为可逆储氢材料的研究现状,主要从制备方法、储氢性能、反应机理、理论计算和存在的问题等方面进行了讨论,同时指出了金属-氮-氢储氢体系的发展趋势.     

甲醇水蒸气重整制氢CuAl2O4催化材料的研究

以γ-Al_2O_3为原料采用原位合成法制备CuAl_2O_4催化材料,通过XRF、XRD、BET和H_2-TPR等手段对催化材料进行表征,考察铜铝物质的量比对CuAl_2O_4催化材料结构、性质及其催化甲醇水蒸气重整制氢性能的影响。结果表明,不同铜铝物质的量比主要影响了铜物种的还原性能,从而影响了其催化甲醇水蒸气重整制氢的性能。当铜铝物质的量比为1∶2时,CuAl_2O_4催化材料的催化性能较好,在反应温度为260℃,水醇物质的量比为1.2,甲醇气体空速为800 h~(-1)时,甲醇转化率为100%,产氢速率为895 mL/(kg·s)。     

基于绿色氢科学理念构筑从低碳制氢到高效储氢的氢能体系

本文从低碳制氢和高效储氢的角度思考及探讨氢能体系绿色化发展过程中的关键科学问题.提出＂绿色氢科学＂理念与＂低碳制氢,高效储氢＂技术发展路线图,以期通过相关科学问题的认识,来构建具有高度原子经济性及可持续性的绿色氢能体系.     

氨硼烷催化水解制氢

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。     

储氢研究进展

氢能是21世纪主要的新能源之一。作为一种新型的清洁能源,氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题,而氢的储存是氢能应用的关键。储氢材料能可逆地大量吸放氢,在氢的储存与输送过程中是一种重要载体。本文综述了目前所采用或正在研究的主要储氢材料与技术,如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等,比较了各种储氢的优缺点,并指出其相关发展趋势。     

储氢研究进展

氢能是21世纪主要的新能源之一.作为一种新型的清洁能源,氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题,而氢的储存是氢能应用的关键.储氢材料能可逆地大量吸放氢,在氢的储存与输送过程中是一种重要载体.本文综述了目前所采用或正在研究的主要储氢材料与技术,如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等,比较了各种储氢的优缺点,并指出其相关发展趋势.     

储氢研究进展

氢能是21世纪主要的新能源之一。作为一种新型的清洁能源，氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题，而氢的储存是氢能应用的关键。储氢材料能可逆地大量吸放氢，在氢的储存与输送过程中是一种重要载体。本文综述了目前所采用或正在研究的主要储氢材料与技术，如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等，比较了各种储氢的优缺点，并指出其相关发展趋势。     

甲醇水蒸气重整制氢Cu/ZnO/Al2O3催化剂的研究

燃料电池作为一种无污染、高效率的能源引起世界各大汽车公司的广泛关注[1,2]。用于燃料电池的燃料目前研究较多的是氢气,用氢气作燃料存在储存、安全、运输等问题,寻求合适贮氢方法或替代燃料,实现车载制氢是解决问题的办法。甲醇作为液体燃料,因具有高能量密度,低碳含量,以及运输和贮存等优势成为车载制氢的理想燃料,甲醇水蒸气重整制氢反应也成为研究的热点[3～10]。车载制氢对甲醇水蒸气重整制氢反应体系中的产氢速率,氢气和CO的含量都有一定的要求。尤其对CO含量要求更为苛刻,因CO易引起燃料电池阳极催化剂中毒[11,12]。因此,开…     

新型高效甲醇水相低温制氢催化剂

<正>新能源的开发和利用能有效缓解能源危机和环境问题。氢能单位质量燃烧热值高,生成的尾气清洁无污染,是重要的新能源材料。氢燃料电池可以将氢能高效地转化为电能,然而,氢气的存储和输运一直是阻碍氢能大规模应用的瓶颈[1]。将氢气储存于液体燃料再通过催化反应原位释放氢气并供给燃料电池使用是一种行之有效的间接储氢策略[2,3]。甲醇作为一种候选液态储氢介质具有单位体积储氢量高、活化温度低、副产物少以     

MAlH4(M=Li,Na)储氢材料*

氢能是一种新型的清洁能源,有望替代碳经济,而氢的储存是氢能应用的关键。近年来,研究集中在具有储氢容量高和可逆性好等优点的固态储氢材料上。许多新型储氢材料不断出现,其中以MAlH₄(M=Li, Na)为代表的金属复合氢化物体系被认为是最有前景的储氢材料之一。本文综述了MAlH₄(M=Li, Na)作为可逆储氢材料的研究现状,主要从吸放氢反应、储氢性能、反应机理、理论计算和存在的问题等方面进行了讨论,并指出其相关发展趋势。     

Low-Temperature Direct Electrochemical Methanol Reforming Enabled by CO-Immune Mo-Based Hydrogen Evolution Catalysts

Hydrogen storage in the form of intermediate artificial fuels such as methanol is important for future chemical and energy applications, and the electrochemical regeneration of hydrogen from methanol is thermodynamically favorable compared to direct water splitting. However, CO produced from methanol oxidation can adsorb to H₂-evolution catalysts and drastically reduce activity. In this study, we explore the origins of CO immunity in Mo-containing H₂-evolution catalysts. Unlike conventional catalysts such as Pt or Ni, Mo-based catalysts display remarkable immunity to CO poisoning. The origin of this behavior in NiMo appears to arise from the apparent inability of CO to bind Mo under electrocatalytic conditions, with mechanistic consequences for the H₂-evolution reaction (HER) in these systems. This specific property of Mo-based HER catalysts makes them ideal in environments where poisons might be present.     

R&D activities in Japan on methanol synthesis from CO2 and H2

Methanol synthesis from CO₂ and H₂ can be a useful process for conversion and transportation of hydrogen energy derived from non-fossil energies. More than ten research groups in Japan have extensively investigated the methanol synthesis from both academic and practical points of view. Recent R&D activities in Japan for developing high performance catalysts, for elucidating the reaction mechanism and also for operating a bench scale plant have been reviewed in this paper.     

Methanol Synthesis at a Wide Range of H2/CO2 Ratios over a Rh-In Bimetallic Catalyst

There is increasing interest in capturing H₂ generated from renewables with CO₂ to produce methanol. However, renewable hydrogen production is expensive and in limited quantity compared to CO₂. Excess CO₂ and limited H₂ in the feedstock gas is not favorable for CO₂ hydrogenation to methanol, causing low activity and poor methanol selectivity. Now, a class of Rh-In catalysts with optimal adsorption properties to the intermediates of methanol production is presented. The Rh-In catalyst can effectively catalyze methanol synthesis but inhibit the reverse water-gas shift reaction under H₂-deficient gas flow and shows the best competitive methanol productivity under industrially applicable conditions in comparison with reported values. This work demonstrates a strong potential of Rh-In bimetallic composition, from which a convenient methanol synthesis based on flexible feedstock compositions (such as H₂/CO₂ from biomass derivatives) with lower energy cost can be established.     

Methanol Synthesis at a Wide Range of H2/CO2 Ratios over a Rh‐In Bimetallic Catalyst

There is increasing interest in capturing H₂ generated from renewables with CO₂ to produce methanol. However, renewable hydrogen production is expensive and in limited quantity compared to CO₂. Excess CO₂ and limited H₂ in the feedstock gas is not favorable for CO₂ hydrogenation to methanol, causing low activity and poor methanol selectivity. Now, a class of Rh‐In catalysts with optimal adsorption properties to the intermediates of methanol production is presented. The Rh‐In catalyst can effectively catalyze methanol synthesis but inhibit the reverse water‐gas shift reaction under H₂‐deficient gas flow and shows the best competitive methanol productivity under industrially applicable conditions in comparison with reported values. This work demonstrates a strong potential of Rh‐In bimetallic composition, from which a convenient methanol synthesis based on flexible feedstock compositions (such as H₂/CO₂ from biomass derivatives) with lower energy cost can be established.     

稀土掺杂改性对Cu/ZnAl水滑石衍生催化剂甲醇水蒸气重整制氢性能的影响

采用原位合成法在γ-Al₂O₃表面合成了锌铝水滑石,再通过顺次浸渍法制备了一系列掺杂稀土改性的M（M=Y、La、Ce、Sm、Gd）/Cu/ZnAl催化材料,并将其应用于甲醇水蒸气重整制氢反应。探讨了稀土掺杂改性对Cu/ZnAl催化剂催化性能的影响,并采用XRD、SEM-EDS、BET、H₂-TPR、XPS和N₂O滴定等手段对催化剂进行了表征。结果表明,催化剂的活性与Cu比表面积和催化剂的还原性质密切相关,Cu比表面积越大,还原温度越低,催化活性越高。稀土Ce、Sm、Gd的引入能改善活性组分Cu的分散度、Cu比表面积以及催化剂的还原性质,进而提高催化剂的催化活性。其中,Ce/Cu/ZnAl催化剂表现出最佳的催化活性,在反应温度为250 ℃时,甲醇转化率达到100%,CO含量为0.39%,相比Cu/ZnAl催化剂,甲醇转化率提高了近40%。     

Rapid Production of High‐Purity Hydrogen Fuel through Microwave‐Promoted Deep Catalytic Dehydrogenation of Liquid Alkanes with Abundant Metals

Hydrogen as an energy carrier promises a sustainable energy revolution. However, one of the greatest challenges for any future hydrogen economy is the necessity for large scale hydrogen production not involving concurrent CO₂ production. The high intrinsic hydrogen content of liquid‐range alkane hydrocarbons (including diesel) offers a potential route to CO₂‐free hydrogen production through their catalytic deep dehydrogenation. We report here a means of rapidly liberating high‐purity hydrogen by microwave‐promoted catalytic dehydrogenation of liquid alkanes using Fe and Ni particles supported on silicon carbide. A H₂ production selectivity from all evolved gases of some 98 %, is achieved with less than a fraction of a percent of adventitious CO and CO₂. The major co‐product is solid, elemental carbon.     

Efficient Disproportionation of Formic Acid to Methanol Using Molecular Ruthenium Catalysts

The disproportionation of formic acid to methanol was unveiled in 2013 using iridium catalysts. Although attractive, this transformation suffers from very low yields; methanol was produced in less than 2 % yield, because the competitive dehydrogenation of formic acid (to CO₂ and H₂) is favored. We report herein the efficient and selective conversion of HCOOH to methanol in 50 % yield, utilizing ruthenium(II) phosphine complexes under mild conditions. Experimental and theoretical (DFT) results show that different convergent pathways are involved in the production of methanol, depending on the nature of the catalyst. Reaction intermediates have been isolated and fully characterized and the reaction chemistry of the resulting ruthenium complexes has been studied.     

An Update on Formic Acid Dehydrogenation by Homogeneous Catalysis

Formic acid (FA) has been extensively studied as one of the most promising hydrogen energy carriers today. The catalytic decarboxylation of FA ideally leads to the formation of CO₂ and H₂ that can be applied in fuel cells. A large number of transition‐metal based homogeneous catalysts with high activity and selectivity have been reported for the selective FA dehydrogentaion. In this review, we discussed the recent development of C,N/N,N‐ligand and pincer ligand‐based homogeneous catalysts for the FA dehydrogenation reaction. Some representative catalysts are further evaluated by the CON/COF assessment (catalyst on‐cost number)/(catalyst on‐cost frequency). Conclusive remarks are provided with future challenges and opportunities.     

Promoted H2 Generation from NH3BH3 Thermal Dehydrogenation Catalyzed by Metal–Organic Framework Based Catalysts

The application of ammonium borane (AB) as a hydrogen storage material is limited by the sluggish kinetics of H₂ release. Two catalysts based on metal–organic frameworks (MOFs) have been prepared either by applying MOF as precursors or by the in situ reduction method. In the release of H₂ from AB, the high H₂ content of the whole system, the remarkably lower reaction onset temperature, the significantly increased H₂ release rates at ≤90 °C, and the decreased reaction exothermicity have all been achieved with only 1.0 mol % MOF‐based catalyst. Moreover, the clear catalytic diversity of three catalysts has been observed and discussed. The in situ synthesized Ni⁰ sites and the MOF supports in the catalysts were proven to show significant and different effects to promote the catalytic activities. With MOF‐based catalysts, both the enhanced kinetics and the high H₂ capacity of the AB system present great advantages for future use.     

Hydrogen Production from a Methanol–Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions

An efficient catalytic system for the production of hydrogen from a methanol–water solution has been developed using a new anionic iridium complex bearing a functional bipyridonate ligand as a catalyst. This system can be operated under mild conditions [weakly basic solution (0.046 mol L^?1 NaOH) below 100 °C] without the use of an additional organic solvent. Long‐term continuous hydrogen production from a methanol–water solution catalyzed by the anionic iridium complex was also achieved.