高效率氢氧化镁脱硫技术在越南某60 MW热电工程中的应用

文章描述了高效率氢氧化镁脱硫技术在越南某60 MW热电工程中的应用。WFGD湿法脱硫的原理是藉由喷洒氢氧化镁Mg(OH)₂浆液与锅炉烟气反应生成无害的硫酸镁(MgSO₄)溶剂,以减少二氧化硫排放。台朔重工(宁波)有限公司采用创新的方法修改WFGD工艺以达到严格的排放要求,系统对于锅炉负载和SO₂含量的变化具有灵活的弹性。     

硝酸盐/膨胀石墨储热材料的制备及热性能研究

为了得到膨胀石墨(EG)含量对NaNO₃-KNO₃/EG复合储热材料导热系数的影响,通过水溶液法,采用NaNO₃-KNO₃共晶盐作为储热材料,不同质量分数的EG作为基体材料,制备出NaNO₃-KNO₃/EG复合储热材料。分别用同步热分析仪(STA)和激光闪射仪(LFA)测量了材料的潜热和导热系数。结果表明,NaNO₃-KNO₃/EG复合材料的潜热随EG含量的增加而减小,导热系数相较于纯硝酸盐均有明显提升。添加20%的EG时,复合材料的平均导热系数可以达到3.95 W/(m·K),约为纯硝酸盐的7.4倍。将EG加入到二元硝酸盐中制备成复合储热材料是提高其传热性能的一种有前景的候选材料。     

纳米金属/石蜡复合相变蓄热材料的实验研究

以石蜡为相变材料基体、纳米金属铜、镍、铝、铁和锌为导热增强剂、油酸为分散剂,采用超声波震荡法制备纳米金属/石蜡复合相变蓄热材料体系。通过复合蓄热体系的步冷曲线分析,结果显示纳米铁为有效导热增强剂。对不同质量分数纳米铁/石蜡复合相变蓄热体系进行DSC和导热系数测试分析,结果表明:随着纳米铁质量分数的增加,复合材料的导热系数逐渐增大,相变潜热值逐渐降低,相变温度变化不大;纳米铁质量分数为0.1%时,复合材料的固态导热系数可增大2.8倍,相变潜热值下降1.1%。     

石墨烯包封Na3V2(PO4)3用作钠离子电池负极材料的电化学性能探究

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...     

纳米Fe2O3/硬脂酸/十八醇纳米复合相变蓄热材料的性能研究

针对有机相变材料热导率低的问题,将高热导率的纳米Fe₂O₃添加到硬脂酸/十八醇二元有机复合蓄热相变材料中,制备纳米复合蓄热相变材料。从分散剂的种类、分散剂与纳米材料的添加量以及超声时间4个方面研究其对纳米复合相变蓄热材料的稳定性及热物性的影响。结果表明,阴离子表面活性剂的分散效果优于阳离子和非离子表面活性剂。复合相变材料中添加质量分数为0.8%,十二烷基苯磺酸钠(SDBS)和质量分数为0.4%Fe₂O₃的体系,超声时间为80 min时,纳米Fe₂O₃在相变材料中的分散效果最好。添加纳米Fe₂O₃后复合蓄热相变材料的相变潜热及相变温度有所下降,热导率提高34.9%。300次热循环复合相变材料的相变温度波动区间不超过0.41℃,相变潜热波动区间不超过4.0%,热稳定性良好。     

Capacitive performance and cycling stability of NixCo1-x(OH)2 xerogels

研究了Ni_xCo_1-x(OH)₂干凝胶中钴含量对其电性能及循环稳定性的影响。用溶胶-凝胶法制备了Ni_xCo_1-x(OH)₂干凝胶材料,用液氮吸附、XPS和XRD研究了含钴Ni(OH)₂干凝胶的组成和结构,用恒电流技术研究了它们的电容性能。结果表明,Ni_xCo_1-x(OH)₂干凝胶具有较高的比表面积和丰富的中孔;添加钴改善了Ni_xCo_1-x(OH)₂干凝胶的倍率性能,当钴含量达到24%时效果最佳;充放电后Co_xNi_1-x(OH)₂干凝胶的晶态结构仍是β-Ni(OH)₂晶相结构,钴含量20%以上的Co_xNi_1-x(OH)₂干凝胶充放电后微晶尺寸变化不明显;组成的活性炭/ Ni_0.76Co_0.24(OH)₂干凝胶电容器20 mA/cm²充放电循环时,库仑效率达到95%以上,循环100000次以上,电容器的比容量仍保持在90%以上。在长循环过程中,Ni_0.76Co_0.24(OH)₂干凝胶的微晶尺寸变化不大,微晶晶胞a轴逐渐变大、c轴逐渐缩小,晶胞参数趋向理想的β-Ni(OH)₂晶体。     

MIL-101(Cr)-NH2/CaCl2复合材料的热化学蓄热性能研究

将金属有机骨架MIL-101(Cr)-NH₂与CaCl₂通过浸渍的方法复合得到MIL-101(Cr)-NH₂/CaCl₂热化学蓄热复合材料。采用X射线衍射分析仪（XRD）、扫描电子显微镜（SEM）、能谱分析（EDS）、全自动比表面积及孔径分析仪以及同步热分析仪（TG-DSC）等分析了复合材料的表观形貌、盐含量、比表面积和蓄热密度等参数。结果显示,复合材料的盐含量为49%,在30℃、32%湿度下的最大吸水量为0.54 g(H₂O)/g(样品),蓄热密度达到了1 204 kJ/kg,并且在经历了17次吸附-解吸循环后,其蓄热密度仅降低了6.5%,表现出优异的循环稳定性,出色的吸附性能表明这一新型复合材料在太阳能蓄热领域具有广阔的应用前景。     

O2/CO2/H2O气氛下CO燃烧机理的分子动力学模拟研究

采用反应分子动力学(ReaxFF MD)模拟方法研究了O₂/CO₂/H₂O气氛下CO的燃烧。结果表明：根据化学平衡原理,高浓度CO₂抑制CO的氧化,同时CO₂在高温下参与反应CO₂+H—→CO+OH,进一步抑制CO氧化。在较低温度条件下,较高浓度H₂O的三体效应显著,抑制了CO氧化。另一方面,在较高温度条件下,H₂O参与的H₂O+H—→H₂+OH和H₂O+O—→OH+OH反应占据其化学作用的主导地位,进而促进CO氧化。随着O₂浓度的增加,CO的氧化速度加快。     

自支撑CC/NiS2纳米片中间层制备与锂硫电池性能研究

多硫离子的穿梭效应是限制锂硫电池发展的一个关键问题。通过水热法和进一步的硫化反应合成了自支撑的碳布/二硫化镍纳米片(CC/NiS₂)复合材料,并将其用作锂硫电池中间层来有效抑制多硫离子的穿梭效应。NiS₂纳米片均匀生长在CC表面,具有较大的比表面积和优异的催化活性,能够显著增强对多硫离子的化学吸附能力并促进电化学反应动力学。相比于碳布(CC)中间层电池,CC/NiS₂中间层电池具有明显提高的倍率性能和良好的循环寿命,在0.5C下放电的初始比容量为1 254 mA·h·g^-1(增加52%),在2C下循环300圈后的比容量仍高达928 mA·h·g^-1,容量衰减率仅为每圈0.015%。     

CaO/CaCO3储能系统材料设计研究进展

为了解决CaO/CaCO₃化学储能系统中材料循环稳定性差、导热系数低、吸光性差的问题,从钙基原料的选择、复合材料中元素的掺杂、运行条件的调整等方面探讨了改善钙基材料性能的方法。结果表明：Al、Mn、Ti等元素的添加可以在材料内形成惰性氧化物,抑制烧结,提高材料的循环稳定性;掺杂具有较高导热系数的材料如Al₂O₃、MgO、SiO₂、ZnO,可以增强材料的导热性能;掺杂Mn、Cu、Fe、Co、Cr等元素能够提高材料的光谱吸收率。相关总结可以为热化学储能材料的设计提供参考。     

Dehydration and hydration behavior of metal-salt-modified materials for chemical heat pumps

Lithium chloride (LiCl) modified magnesium hydroxide (Mg(OH)₂) is a potential new material for chemical heat pumps. However, there is insufficient information concerning its dehydration and hydration behavior. In this study, the dehydration and hydration reactions, corresponding to the heat storage and the heat output operations, respectively, of authentic Mg(OH)₂ and LiCl-modified Mg(OH)₂ were investigated by thermogravimetric methods and near infrared spectroscopy. The dehydration of authentic Mg(OH)₂ proceeded as a one-step reaction. In contrast, the dehydration of LiCl-modified Mg(OH)₂ occurred in two steps. The dehydration reaction rates were increased by LiCl modification of the Mg(OH)₂ surface, while the activation energy for the first-order dehydration reaction was lowered. The mechanism for the hydration reaction of magnesium oxide (MgO) was different to that for the hydration of LiCl-modified MgO. This difference was explained by the effect of the LiCl on the MgO particle surface.     

A Facile Method to Construct Graphene Oxide–Based Magnesium Hydroxide for Chemical Heat Storage

Mg(OH)₂ nanoparticles anchored on graphene oxide (GO) were facilely prepared by a hydrothermal method. The main diameter scale of nanoparticles on the graphene sheet was about 25–50 nm shown by transmission electron microscopy characterization results. X-ray diffraction results indicated that the nanoparticles are in accordance with the data on magnesium hydroxide. This material exhibited significantly improved heat storage capacity and a higher hydration rate than pure magnesium oxide, and the introduction of GO leads to greatly increased thermal conductivity of the nanocomposites. As a novel thermochemical heat storage material, Mg(OH)₂/GO has huge potential for high-efficiency energy systems.     

Optimization of magnesium hydroxide composite material mixed with expanded graphite and calcium chloride for chemical heat pumps

A composite chemical heat storage material (EMC) comprising a mixture of expanded graphite (EG), magnesium hydroxide (Mg(OH)₂), and calcium chloride (CaCl₂) was developed as a magnesium oxide/water chemical heat pump reactant. The optimization of a mixing weight ratio between the Mg(OH)₂ content of EMC and EMC itself was discussed from the viewpoints of both heat storage capacity and reactivity by considering the reaction rate constants from a kinetic analysis. It was confirmed that the dehydration reactivity of EMC increased as the mixing weight ratio decreased; however, the heat capacity of the EMC unit mass decreased. A multiplied factor consisting of the multiplied value dehydration rate constant and mixing weight ratio was introduced. It was suggested that a weight ratio of approximately 0.80 was the optimized value when the mixing molar ratio between CaCl₂ and Mg(OH)₂ was 0.10. Dehydration of EMC with an optimized mixing weight ratio and dehydration of pure Mg(OH)₂ were conducted under various temperatures to compare the reaction rate constants of each material. From this study, it was demonstrated that EMC performed better on dehydration than pure Mg(OH)₂.     

The electrochromic properties of hydrated nickel oxide films formed by colloidal and anodic deposition

Hydrated nickel oxide NiO_xH_y films were deposited onto indium tin oxide (ITO) coated glass by two methods (i) colloidal precipitation and (ii) anodic electrodeposition. The electrochromic properties of hydrated nickel oxide films were studied by transmittance measurements (UV/VIS/NIR), and Fourier transform infrared reflectance spectroscopy as a function of the key deposition parameters. The solar transmittance was calculated for films switched in both bleached and coloured states. The best results were achieved for films produced by anodic electrodeposition from stable solutions with solar transmittance T_s(bleached) = 0.82 and T_s(coloured) = 0.22. Corresponding optimum values for the films produced by colloidal precipitation were solar transmittance T_s(bleached = 0.82 and T_s(coloured) = 0.47. Fourier transform spectrophotometry was used for elucidating changes in hydration, hydroxylation and for the characterization of structural characteristics in the bleached and coloured states. It was found that free OH stretching vibration at 3647 cm⁻¹ corresponds to Ni(OH)₂ for both anodic and colloidal deposited films in the reduced (bleached) state. In the oxidised state hydrogen bonded OH at 3360 cm⁻¹ is observed.     

Improvement of the catalytic properties of Ti-doted Raney-Nickel for H2-Anodes of alkalione fuel cells by Ni(OH)2-surface coating

This paper belongs to a series of three dealing with the latest improvements in the alkaline H₂---O₂ fuel cells operating under mild conditions thanks to their Raney-Ni-catalysts. The first of these papers describes the benefication of a Ni(OH)₂ surface coating on the catalytic activity of Ti-doted Raney-Ni in supported electrodes. This Ni(OH)₂ surface coating is produced by carefully optimized oxidation. A Ni(OH)₂-content of 5 up to 6wt% increases the attainable current density by the factor 3–4. In addition, the exchange current density is markedly enlarged up to a Ni(OH)₂-fraction by 5%, but remains unchanged when further increasing the Ni(OH)₂ percentage. Thus, one may conclude that the Ni(OH)₂ surface coating improves markedly the charge exchange reaction. On the other side, the surface diffusion of H-atoms on the pore walls to the location of charge exchange reaction is hindered by too much Ni(OH)₂.     

Generation of enhanced stability of SnO/In(OH)3/InP for photocatalytic water splitting by SnO protection layer1

InP shows a very high efficiency for solar light to electricity conversion in solar cell and may present an expectation property in photocatalytic hydrogen evolution. However, it suffers serious corrosion in water dispersion. In this paper, it is demonstrated that the stability and activity of the InP-based catalyst are effectively enhanced by applying an anti-corrosion SnO layer and In(OH)₃ transition layer, which reduces the crystal mismatch between SnO and InP and increases charge transfer. The obtained Pt/SnO/In(OH)₃/InP exhibits a hydrogen production rate of 144.42 µmol/g in 3 h under visible light illumination in multi-cycle tests without remarkable decay, 123 times higher than that of naked In(OH)₃/InP without any electron donor under visible irradiation.     

Production of hydrogen gas from novel chemical hydrides

Six ligand-stabilized complexes have been synthesized and tested for use as hydrogen storage media for portable fuel cell applications. The new hydrides are: [HC(3,5-Me₂pz)₃]LiBH₄ (1), {[H₂C(3,5-Me₂pz)₂]Li(BH₄)}₂ (2) (pz = pyrazolyl), [(TMEDA)Li(BH₄)]₂ (3) (TMEDA = (CH₃)₂NCH₂CH₂N(CH₃)₂), [HC(pz)₃]LiBH₄ (4), {[H₂C(pz)₂]Li(BH₄)}₂ (5) and Mg(BH₄)^.₂ 3THF (6) (THF = tetrahydrofuran). Hydrolysis reactions of the compounds liberate hydrogen in quantities which range from 56 to 104 (± 5%) percent of the theoretical yield. Gas chromatographic analysis of the product gases from these reactions indicate that hydrogen is the only gas produced. Thermally initiated reactions of the novel compounds with NH₄Cl were unsuccessful. Although the amount of hydrogen energy which can be theoretically obtained per unit weight is lower than that of the classical hydrides such as LiBH₄ and NaBH₄, the reactions are less violent and hydrolysis of compounds 1, 2, 4, 5 and 6 releases less heat per mole of hydrogen generated.