新能源汽车电池用无镁储氢合金的制备与性能研究

采用真空电弧熔炼和925 ℃/12 h退火的方法制备了Y_1-xLa_xNi_3.25Al_0.15Mn_0.15储氢合金（x=0~1）,研究了x值对储氢合金物相组成和电化学性能的影响。结果表明,x=0和0.15的储氢合金主要由LaNi₅和Ce₂Ni₇相组成,x=0.25、0.33和0.5储氢合金主要由Ce₅Co₁₉和Ce₂Ni₇相组成,x=0.75和1储氢合金主要由PuNi₃、LaNi₅和Ce₂Ni₇相组成;相同充放电循环周次下,x=0.15~1储氢合金的放电容量和抗氢致非晶化能力都高于x=0储氢合金,且随着x从0增加至1,储氢合金的最大放电容量（C_max）、容量保持率（S₁₀₀）、氢扩散系数（D₀）和高倍率放电性（HRD₉₀₀）都呈现先增加后减小趋势,在x=0.33时取得C_max、S₁₀₀、D₀和HRD₉₀₀最大值。Y_1-xLa_xNi_3.25Al_0.15Mn_0.15储氢合金的循环稳定性与合金电极的耐腐蚀性密切相关,高倍率放电性能取决于储氢合金的氢扩散速率。     

球磨时间对石墨烯复合材料电化学性能的影响

采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和电化学工作站等手段研究了球磨时间（0~60 min）对石墨烯/La₁₅Fe₂Ni₇₁Mn₆B₂Al₂复合材料微观结构和电化学性能的影响。结果表明,球磨时间为0~60 min制备的石墨烯复合储氢合金都主要由La₃Ni₁₃B₂、（Fe,Ni）、LaNi₅相组成,其中LaNi₅相的晶胞体积会随着球磨时间的增加而减小。随着球磨时间从0 min增加至60 min,石墨烯复合储氢合金的电荷转移电阻先减小后增大、交换电流密度先增大后减小、氢扩散系数和荷电保持率先增加后减小,在球磨时间为40 min时取得电荷转移电阻最小值,交换电流密度、氢扩散系数和荷电保持率最大值。此外,在相同循环次数下球磨时间为40 min制备的石墨烯复合储氢合金具有相对较高的放电比容量。适宜的石墨烯/La₁₅Fe₂Ni₇₁Mn₆B₂Al₂复合材料的球磨时间为40 min,此时氢扩散系数和荷电保持率分别为1.259×10^-8 cm²/s和97.62%,具有较好的电化学性能,这主要与此时复合材料粉末颗粒较为细小、均匀且结晶度较高等有关。     

炼厂多杂质氢网络的集成

利用演化法对某炼厂多杂质氢网络进行优化。在考虑源阱之间的各种匹配可能和氢源之间的互补可能基础上,依次求取最大匹配流量矩阵（M矩阵）、潜在匹配流量矩阵（P矩阵）和最优匹配流量矩阵（O矩阵）,确定系统的最小公用工程消耗量为1495.83 m³·h^-1,其节约量为1004.17m³·h^-1,占现行新氢消耗量的40.2%。此外,根据O矩阵确定了相应的最优氢分配网络。     

提纯回用氢系统优化

过程氢源的提纯回用能够减少氢气公用工程用量,是炼油厂节氢降耗的有效途径。今利用改进的问题表确定提纯回用氢系统的最小氢公用工程用量和最优提纯装置入口流率。改进的问题表法将能够顺利确定多股外部氢源(氢气公用工程和提纯产品气)的流率目标值并识别废氢流股。案例文献的优化结果表明,文中所提出的方法能够克服原文献仅有一股过程氢源提纯回用的局限,氢公用工程用量和废氢流股的流率分别减少了8.6%和7.2%。     

三氢化铝应用于燃料电池的研究进展

三氢化铝（AlH₃）具有储氢量大、质量轻、释氢温度较低、产物洁净等优势,是应用于燃料电池的理想储氢材料,但因其合成成本较高、室温条件下难以再生,目前尚未大规模应用。本文从燃料电池对储氢材料的要求出发,介绍了AlH₃的基本性质、合成再生方法及其释氢性能与改进方法,简述了基于AlH₃的储氢装置及系统、车载储氢和便携式电源等应用的国内外研究现状,提出今后研究工作应集中在降低释氢温度、调控释氢速率、提高释氢率、设计高效储氢系统及开发低成本制备和再生工艺。     

考虑多对耦合源阱的氢网络优化方法及其应用

在氢网络中,氢源氢阱通常连接于同一个耗氢反应器,为耦合源阱;反应器操作参数的改变影响该耦合源阱参数。在同一个氢网络中可能存在多对耦合源阱,考虑多对耦合源阱的氢网络优化能够进一步为炼厂降低氢耗,提高经济效益。通过分析氢网络的公用工程与多对耦合源阱的关系,推导确定了公用工程迁量与反应器耗氢以及耦合源阱之间的方程。据此建立了耗氢反应器参数和氢网络图像集成优化方法。案例研究表明,该方法简单、容易理解,能够直观给出公用工程迁量与反应器进口温度之间的关系。     

镁基储氢材料的性能及研究进展

镁基储氢材料具有储氢容量高、价格低廉、在自然界中镁资源丰富等优点，被认为是最具有发展前景的一类固态储氢材料。由于MgH₂稳定性好且放氢焓值高(75kJ/mol H₂)，氢分子在Mg表面解离能高及氢原子在镁晶格中扩散速率慢，导致吸放氢热力学稳定、动力学缓慢，从而限制了其在储氢方面的应用。对于镁基储氢材料性能的改善，目前已经取得了许多研究成果。本文综述了国内外镁基储氢材料的研究报道，归纳了镁基储氢材料的改性方法，重点阐述了合金化、纳米化和添加催化剂对于优化和改善热力学和动力学性能以及吸放氢机理的影响。最后对该领域的研究成果和发展前景进行了总结和展望，基于现有分析认为，在未来的研究中可以综合运用添加催化剂和纳米化改性双重机制对MgH₂体系热力学性能进行调控，以获得具有高容量、高性能的Mg/MgH₂储氢体系，满足商业化应用的要求。     

Cu、Fe掺杂六铝酸盐催化剂的催化还原脱硝性能

采用共沉淀法制备Cu和Fe掺杂的六铝酸盐催化剂（SrCu_xFe_1-xAl₁₁O_19-δ,x=0、0.2、0.4、0.5、0.6、0.8、1）,通过XRD、H₂-TPR和BET等方法对催化剂结构及性能进行研究,并考察以CO为还原剂的催化脱硝活性。结果表明,用碳酸铵作为沉淀剂在1 200 ℃焙烧4 h可形成完整的六铝酸盐晶型,Cu和Fe能取代Al³⁺,较好地促进六铝酸盐晶体结构的形成;SrCu_xFe_1-xAl₁₁O_19-δ催化剂脱硝催化活性较好,在温度不超过450 ℃和空速6 000 h-1条件下,均使NO转化率超过99%。在SrCu_xFe_1-xAl₁₁O_19-δ六铝酸盐催化剂中,Cu和Fe均为催化脱硝的主要活性元素,两种元素按一定量配比更有利于提升脱硝效果,最优催化剂为SrCu_0.5Fe_0.5Al₁₁O_19-δ。     

成分对汽车用（La0.7Mg0.3）Nix合金储氢特性的影响

为开发出具有高循环寿命和高储氢性能的新能源汽车用稀土镁基储氢合金,考察了铸态和退火态的铸锭/快淬（La_0.7Mg_0.3）Ni_x（x=2.0、2.5、3.0）储氢合金的微观结构、物相组成和储氢特性。结果表明,当x=2.5时快淬法储氢合金具有较好的吸放氢平台压力,PCT曲线中体现出完全脱氢特征,吸氢容量约为1.44%（质量分数）。经过850~950 ℃退火处理,铸锭法（La_0.7Mg_0.3）Ni_2.5储氢合金相较（La_0.7Mg_0.3）Ni_2.0储氢合金具有更高的吸放氢平台压和更宽的吸放氢平台,表明前者具有相对更好的吸放氢性能;不同退火温度下（La_0.7Mg_0.3）Ni_2.5储氢合金的吸放氢平台压较为接近,吸氢和放氢容量可达到1.6%（质量分数）。铸锭法和快淬法（La_0.7Mg_0.3）Ni_x储氢合金中的LaNi₅和（LaMg）Ni₃相会随着退火温度的升高而逐渐转变为（LaMg）₂Ni₇相;铸锭法和快淬法（La_0.7Mg_0.3）Ni_2.5储氢合金的表面粉末颗粒分别在退火温度为950 ℃和900 ℃时最为细小。     

固体氧化物燃料电池双钙钛矿陶瓷阳极缺陷结构设计与性能调控

研究了固体氧化物燃料电池Sr₂Fe Mo_0.6Mg_0.25Al_0.15O₆ (SFMMA)双钙钛矿阳极的晶体缺陷结构、热膨胀性能、电荷传输特性、氧化还原稳定性以及电化学性能。结果表明:SFMMA室温下为I 4/m四方结构,400℃时材料转变为F m 3 m立方结构。SFMMA材料的实际晶体结构式为Sr₂(Fe_0.75Mg_0.25)(Mo_0.6Fe_0.25Al_0.15)O6-δ,材料晶格中含有大量反位缺陷FeB’以及—Fe_B—O—Fe_B’—键,有利于氧空位的形成及氧离子的迁移扩散。SFMMA的热膨胀系数在25~400℃和400~900℃范围内分别为13.0×10^–6K^–1和17.6×10^–6K^–1,在氢气气氛下600~900℃温度范围内电导率超过35 S·cm^–1,并且具有较快的氧表面交换特性以及非常优异的氧化还原循环结构稳定性。在900,850,800℃和750℃时,湿润H₂(3%H₂O,50 m L/min)气氛中,SFMMA/La_0.4Ce_0.6O₂(LDC)/La_0.8Sr_0.2Ga_0.8Mg_0.2O₃(LSGM)/LDC/SFMMA对称半电池面比电阻分别为0.096,0.142,0.239Ω·cm²和0.447Ω·cm²。以SFMMA为阳极组装电解质支撑型单电池SFMMA/LDC/LSGM (300μm)/Pr Ba_0.5Sr_0.5Co_1.5Fe_0.5O₅+δ,850℃时电池最大功率密度可达886 m W·cm^–2。     

Pinch Location of the Hydrogen Network with Purification Reuse

In the hydrogen network with the minimum hydrogen utility flow rate, the pinch appears at the point with zero hydrogen surplus, while the hydrogen surpluses of all the other points are positive. In the hydrogen purity profiles, the pinch can only lie at the sink-tie-line intersecting the source purity profile. According to the alternative distribution of the negative and positive regions, the effect of the purification to the hydrogen surplus is analyzed. The results show that when the purification is applied, the pinch point will appear neither above the purification feed nor between the initial pinch point and the purification feed, no matter the purification feed lies above or below the initial pinch point. This is validated by two case studies.     

电动汽车用La-Fe-B储氢合金的制备与电化学性能研究

研究了石墨烯含量对储氢合金物相组成和电化学性能的影响。结果表明,不同石墨烯含量储氢合金都主要由La₃Ni₁₃B₂、LaNi₅和（Fe,Ni）相组成,La₃Ni₁₃B₂和（Fe,Ni）相晶胞体积会随着石墨烯含量增加而增大,LaNi₅相晶胞体积会随着石墨烯含量增加而减小。当石墨烯质量分数从0%增加至6%时,储氢合金的最大放电容量先增加后减小,在石墨烯质量分数为4%时取得储氢合金放电容量最大值（288.5 mA·h/g）,且当循环周期为100次时,石墨烯质量分数为4%和6%的储氢合金的放电容量仍然高于未添加石墨烯的储氢合金。相同温度下,添加石墨烯的储氢合金的放电容量都高于未添加石墨烯的储氢合金,且石墨烯质量分数为4%的储氢合金具有最大放电容量。随着石墨烯质量分数从0%增加至6%,储氢合金的电荷转移电阻先减小后增大、电流密度和扩散系数先增大后减小,在石墨烯质量分数为4%时取得电荷转移电阻最小值、电流密度和扩散系数最大值,适宜的石墨烯添加量为4%。     

Electrochemical and crystallographic characterization of Co-free hydrogen storage alloys for use in nickel–metal hydride batteries

Electrochemical and crystallographic characterization of Co-free hydrogen storage alloys containing Si and/or Fe was carried out. In the charge–discharge cycle test, the maximum discharge capacity of a Co-free MmNi_4.3Mn_0.4Al_0.3 (Mm=misch metal) alloy electrode was decreased by the partial substitution of Si and/or Fe for Ni, but the cycle performance was improved. The MmNi_3.6Mn_0.4Al_0.3Si_0.1Fe_0.6 electrode showed the most excellent cycle durability in this study. It was found by SEM, EPMA and XRD that Fe and Si contained in these alloys more or less suppressed the dissolution of Al and the lattice expansion with hydrogen absorption, leading to the long cycle life. This effect was strengthened by the simultaneous partial substitution of Si and Fe for Ni in the Co-free alloy.     

Catalytic combustion of gasified biomass: poisoning by sulphur in the feed

The influence of sulphur on the catalytic combustion of gasified biomass for gas turbine applications has been studied over precious metal and metal oxide based catalysts, namely Pd/LaAl₁₁O₁₈, Pt/LaAl₁₁O₁₈, Pt/La_0.5Ba_0.5Mn_0.5Fe_0.5Al₁₁O₁₉, La_0.5Ba_0.5Mn_0.5Fe_0.5Al₁₁O₁₉ and LaMnAl₁₁O₁₉. The samples were washcoated on cordierite monoliths and tested in a bench-scale reactor with a synthetic low-heating value fuel mixed with air. The fuel gas, that resembles the gas from air-blown fluidised bed gasification of wood, was composed of hydrogen, carbon monoxide, methane, ethene, carbon dioxide, water and nitrogen. Different concentrations of hydrogen sulphide as well as sulphur dioxide were added to the fuel gas. The results show that all samples were deactivated to some extent by addition of sulphur, although poisoning of the catalytic combustion for each fuel component varied depending both on the active phase and on the support and generally was reversible. The palladium catalyst was severely deactivated for combustion of methane, although activity for carbon monoxide and hydrogen was almost maintained. Platinum catalysts were more severely poisoned for carbon monoxide and hydrogen, but not for methane. Metal oxide catalysts were severely deactivated for all fuel components, especially for carbon monoxide, and the La_0.5Ba_0.5Mn_0.5Fe_0.5Al₁₁O₁₉-sample was irreversibly poisoned. The samples were also characterised by BET, XRD, ICP, SEM–EDX, XPS and SIMS.     

Performance of La1−xSrxAl1−y−y′FeyMgy′O3−δ perovskites in methane combustion: effect of aluminum and magnesium content

Perovskites of different La_1−xSr_xAl_1−y−y′Fe_yMg_y′O_3−δ compositions (x=0, 0.1, 0.15, 0.2 and y=0.1, 0.3, 0.5, 0.8) were prepared from a reactive precursor slurry of hydrated oxides. Each sample was aged between 16 and 26 h up to 1473 K. Activity in methane combustion (1%/air) was determined in a plug-flow reactor, with 1 g catalyst and 24 l/h flowrate. Gradual decrease in activity due to thermal aging was observed, the degree of activity loss being composition dependent. Nevertheless, activity of samples aged at 1370 K was nearly independent of composition. The best thermal stability showed LaAl_0.65Fe_0.15Mg_0.2O₃ perovskite. None of the magnesium substituted perovskites performed better than a La_0.85Sr_0.15Al_0.87Fe_0.13O₃ reference sample.     

Novel method for targeting the optimal purification feed flow rate of hydrogen network with purification reuse/recycle

The purification reuse/recycle is one effective resource conservation strategy. In this article, a novel conceptual method is proposed to identify the optimal purification feed flow rate (PFFR) and the corresponding maximum hydrogen utility savings (HUS) of the hydrogen network with purification reuse/recycle. In this method, the sources and sink‐tie‐lines are divided into three regions according to the purified product and purification feed. The quantitative relationship between the HUS and the PFFR is analyzed for the sink‐tie‐lines and sources of each region. With the quantitative relationship line between the HUS and the PFFR of each source plotted, the quantitative relationship diagram can be obtained and can be used to identify the pinch point and the HUS for a given PFFR. Furthermore, the optimal PFFR and the maximum HUS can be identified easily. Three cases are studied to illustrate the applicability of the proposed method. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1964–1980, 2013