中温固体氧化物燃料电池Pr1.2Sr0.8NiO4阴极材料的制备、结构和性能

以相应的氧化物粉末和盐为原料,通过甘氨酸-硝酸盐法合成出了中温固体氧化物燃料电池(IT-SOFC)Pr1.2Sr0.8NiO4(PSNO)阴极原料粉体,并制备出了烧结体试样.采用X射线衍射(XRD)分析对所合成粉体的相组成进行了分析,分别采用热膨胀仪和四端子法对PSNO烧结体试样的热膨胀系数和电导率进行了测定,同时对该阴极材料与Sm0.2Ce0.8O1.9(sco)电解质材料的电化学阻抗谱(EIS)进行了测试分析以SCO作电解质,分别以NiO/SCO和PSNO作阳极和阴极材料,制备出固体氧化物燃料单电池,并对其性能进行测试.实验结果表明,通过甘氨酸-硝酸盐法,在1050℃以上煅烧前驱体,可以获得具有K2NiF4结构的PSNO粉体.所制备的PSNO烧结体试样在200-800℃间的热膨胀系数约为12×10-6 K-1,在450℃下的电导率约为155 S· cm-1,在400-800℃,平均电导活化能为0.034 eV.电化学阻抗谱分析结果表明,在700 ℃下PSNO阴极和SCO电解质间的比表面阻抗(ASR)为0.37Ω·cm2,而Ni-SCO/SCO/PSNO单电池的比表面阻抗为0.61Ω·cm2;所制备的SOFC单电池在800℃下的输出功率为288 mW· cm-2,开路电压为0.75 V.本研究的初步结果表明PSNO 材料是一种综合性能较为优良的新型巾温固体氧化物燃料电池阴极材料.     

复合掺杂氧化物La0.5Sr0.5CoO2.91的性能和稳定性

采用固相反应法和柠檬酸-硝酸盐溶胶-凝胶低温自蔓延燃烧法（简称柠檬酸法）合成了La0.5Sr0.5CoO2．91（LSC）复合氧化物。借助XRD和SEM对不同制备方法合成粉体的晶体结构和晶粒形貌进行了研究。结果表明：固相反应法可制得均一钙钛矿结构的LSC氧化物，柠檬酸法除制得LSC氧化物外，还有LaSrCoO4相的生成。柠檬酸-硝酸盐溶胶-凝胶低温自蔓延燃烧法合成粉体的粒度相对较小。为研究以Ce0．9Gd0.1O1．95（GDC）为电解质的固体氧化物燃料电池阴极材料的性能，将LSC粉体与GDC粉体按6：4（质量比）制备了固体氧化物燃料电池（SOFC）的阴极片。在空气气氛下使用直流四探针法研究了烧结样品300～800℃的电导率，发现由柠檬酸法得到粉体制备的阴极片的电导率值较高。将制备的样品置于马弗炉中800℃条件下烧结800h，比较失效前后电导率的变化情况，并借助XRD，SEM等测试手段分析样品电导率变化的原因。分析发现，失效后两种样品的电导率值都有所降低，且样品中都有新相生成，晶体形貌有较大的变化。     

中温燃料电池阴极材料la0.6sr0.4fe0.8co0.2o3的合成与性能

固体氧化物燃料电池;阴极材料;溶胶-凝胶法     

溶胶-凝胶流动相异型直接甲醇燃料电池性能研究

以掺杂石墨粉的中间相碳微球(MCMB/G)烧结管为阴极支撑体,采用浸涂工艺分别制备了扩散层和催化层并在其外表面包裹Nafion膜,制得管状异型阴极并组装成异型直接甲醇燃料电池;采用溶胶-凝胶法制备了适用于直接甲醇燃料电池的溶胶-凝胶流动相。研究了溶胶-凝胶流动相异型直接甲醇燃料电池的阻抗,考察了阴极支撑体壁厚、阴极扩散层载量、实验温度和溶胶黏度等对电池极化性能的影响。结果表明,异型电池阻抗比传统平板电池大,但活化后电池阻抗明显下降;较低的溶胶黏度和较高的工作温度有利于提高电池性能;支撑体壁厚为1.3 mm、扩散层载量为3.5 mg/cm2时的电极性能最优。     

中温固体氧化物燃料电池复合阴极Pr0.6-zSr0.4Co0.8Fe0.2O3-δ-SDC性能研究

采用改进的溶胶-凝胶法合成固体氧化物燃料电池阴极系粉体Pr0.6-zSr0.4Co0.8Fe0.2O3-δ(PSCF)(z=0,0.02,0.05,0.1)。使用X射线衍射(XRD)、扫描电子显微镜(SEM)对其相结构与形貌进行了分析,结果表明:900℃以上焙烧后的阴极粉体Pr0.6-zSr0.4Co0.8Fe0.2O3-δ(z=0,0.02,0.05,0.1)为单一的钙钛矿结构。1000℃烧结的样品内粒子分布比较均匀,且颗粒内部存在一定程度的空隙,并与电解质附着情况良好。用直流四电极法测试阴极体系样品在400～750℃的电导率,发现各试样混合离子电子电导率均高于786 S.cm-1,能够满足固体氧化物燃料电池对阴极电导率的要求。用交流阻抗法测定PSCF-Ce0.8Sm0.2O1.9体系样品的阻抗谱,得到1000℃烧结的阴极体系对称电池在测试温度为750℃z=0,z=0.02,z=0.05时的极化电阻分别为0.041,0.040,0.034Ω.cm-2。     

BaCe0.5Zr0.4Y0.1O3-δ粉体的溶胶-凝胶法和高温固相法制备及性能表征

分别通过溶胶-凝胶法和高温固相反应法制备了BaCe0.5Zr0.4Y0.1O3-δ粉体.采用热重-差热分析(TG-DTA),粉末X射线衍射(XRD),扫描电子显微镜(SEM),傅立叶红外衍射(FT-IR),N2吸附-脱附等方法对所制备的粉体进行了表征.结果表明:用溶胶-凝胶法在1200 ℃×10 h可以合成纯的BaCe0.5Zr0.4Y0.1O3-δ粉体,合成温度比传统的高温固相反应法降低400 ℃左右;溶胶-凝胶法合成粉体具有多孔结构特征,与固相法合成粉体相比具有较高的比表面积.但致密化试验表明:溶胶-凝胶法合成粉体与固相法合成粉体相比具有较低的烧结活性.溶胶-凝胶法合成粉体颗粒表面残余的有机基团和颗粒内部的大量微孔将在致密化过程中产生空间位阻,从而影响高温下原子的迁移,阻碍材料的致密化过程.     

合成温度对镁离子电池正极材料MgCo_(0.4)Mn_(1.6)O_4的影响

应用溶胶-凝胶法合成镁离子电池正极材料MgCo0.4Mn1.6O4,TG-DTA和XRD测试表明所得MgCo0.4Mn1.6O4粉体表现为单一的尖晶石相.以该材料作镁离子电池正极,其电化学性能与MgCo0.4Mn1.6O4粉体的煅烧温度有关,其中于700℃下煅烧制备的样品表现出相对较好的电化学行为.     

固-溶法制备中温固体氧化物燃料电池高性能La_(0.8)Sr_(0.2)MnO_3-Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_3阴极（英文）

研究了新型固溶法合成La0.8Sr0.2MnO3(LSM)包覆Ba0.5Sr0.5Co0.8Fe0.2O3(BSCF)复合粉体(LSM-BSCF),并探讨了其作为中温固体氧化物燃料电池阴极材料的电化学性能.LSM-BSCF阴极结合了LSM和BSCF阴极的优点,不仅增大了三相界面,而且稳定了微观结构.当温度为600儃750°C时,其极化阻抗为0.61儃0.09Ω·cm2.与溶液注入法制备的高性能电极相比,极大地提高了性能稳定性.     

新型电解质材料CaZr_(0.1)Ti_(0.9)O_3的制备与电性能

采用溶胶-燃烧法合成了可用于固体氧化物燃料电池(SOFC)的新型固体电解质材料CaZr_(0.1)Ti_(0.9)O_3.通过XRD、交流复阻抗等电化学方法对样品的结构、电导性能进行了表征,并考察了材料的烧结性能. 结果表明,溶胶-燃烧法可以成功制备出具有良好烧结性能的CaZr_(0.1)Ti_(0.9)O_3电解质粉末,1 400 ℃下得到的烧结体的相对密度可达到95%. 电性能测试表明,CaZr_(0.1)Ti_(0.9)O_3烧结体在中温范围内具有较高的氧离子电导率(σ_(800 ℃)＝2.24×10~(-3)S/cm)、低的电导活化能(0.89 eV).     

La0.75Sr0.25Cr0.5Mn0.5O3的制备及其NO2气敏性能

利用高温固相反应法和溶胶-凝胶法制备了La0.75Sr0.25Cr0.5Mn0.5O3钙钛矿复合氧化物粉体。采用XRD,TEM对粉体物相组成及颗粒形貌进行表征,并以制备的两种粉体作为敏感材料分别制成管状传感器,测试了其NO2气敏性能。结果表明：采用高温固相反应法和溶胶-凝胶法在不同焙烧温度下,均可制得单相La0.75Sr0.25Cr0.5Mn0.5O3粉体,采用溶胶-凝胶法在800℃焙烧2 h得到的粉体粒径约为20 nm;传感器输出电动势信号对NO2浓度之间呈良好的线性关系;溶胶-凝胶法制得粉体的气敏性能优于高温固相反应法制得粉体的气敏性能。     

On the escape process during phase inversion of an emulsion

This paper deals with a phenomenon which plays an important role in the phase inversion process of emulsions. This process is governed by the interplay of coalescence of droplets, often leading to double emulsions, and the escape of those internal droplets. The latter process retards the inversion process. Coalescence has been the subject of many studies, contrary to the escape event. This paper addresses the escape process both theoretically and experimentally. The model developed analyses the rate of the escape of internal droplets from the mother droplet via a coalescence process, where the internal flow, as generated by the external flow, generates the viscous force for coalescence. Incomplete mixing in the droplet has been assumed. Experimental data on the escape rate of oil droplets from O/W/O emulsions have been analysed using a Computational Fluid Dynamics approach, where the model as indicated above has been incorporated. Experimental data and simulations compare very well. Data have been compared on varying the size of the inner droplets and the rotational speed of the vessel where the double emulsion has been formed and where the escape took place.     

热化学循环分解水制氢研究进展

热化学循环分解水制氢是利用核能或太阳能进行大规模、无污染制氢的有前景的方法 ,已经提出了多种流程.本文对热化学制氢流程及其评价标准进行了综述,重点介绍了碘硫循环、UT-3循环和Westinghouse循环等先进流程的研究进展.     

The principle of increasing mixing character and some of its consequences

The Principle of Increasing Mixing Character, previously postulated by one of us (and derived for the case of an ensemble of isolated systems obeying a master equation) as a stronger version of the second law of thermodynamics, is re-derived using von Neumann's density matrix formulation of statistical mechanics. To make the principle more convenient for applications, it is reformulated in terms of Mixing Homomorphic Functions, a set of state functions all of which must increase in an allowed irreversible process in an-isolated system. The entropy is one such function, but no one function, and no finite set of functions, suffices to determine the increase of mixing character. The principle is extended to the case of a system which is not isolated, but in contact with a heat bath, for which it takes a form which we name the Principle of Decreasing Mixing Distance from the equilibrium distribution. As examples, applications are made to two simple cases: diffusion in an ideal solution, and chemical reactions in ideal gas mixtures.     

反应和分离过程的结合

本文简要介绍了近年来反应和分离过程结合的现状和发展趋势。     

Candelilla Wax Extracted by Traditional Method and an Ecofriendly Process: Assessment of Its Chemical,Structural and Thermal Properties

A comparative study was carried out on the chemical, structural and thermal properties of candelilla wax from four wax-producing communities in Mexico, which was obtained by two extraction processes, the conventional one using sulfuric acid (SA) and an eco-friendly alternative process using citric acid (CA) as the extracting agent. The waxes were analyzed by basic chemistry (acidity, saponification, ester indexes, and others), color, Fourier transform infrared spectroscopy (FTIR), Raman micro-spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and hardness and brittleness measurements. The waxes obtained by the environmentally friendly process showed differences in their physicochemical properties when compared to waxes from the conventional process. In addition, they showed some improvements, such as lighter shades and harder waxes, suggesting that the new environmentally friendly process is a viable option.     

Re-entrant volume phase transition of hydrogel membrane of microcapsule

Re-entrant volume phase transition of hydrogel wall membrane of microcapsules (MC) was first observed using MC suspensions consisting of poly (L-lysine-alt-terephthalic acid) wall and aqueous inner and outer solutions with different pHs. To analyze the dynamics of the re-entrant phase transition, we extended the theory for the swelling and the shrinking dynamics of the microcapsule gel [T. Narita, T. Yamamoto, D. Suzuki, T. Dobashi, Langmuir 19 (2004) 4051]. In the theory, the microcapsule size and the force constant for the driving force which gives rise to the size relaxation were chosen as the thermodynamic variables. The time course of the cross-sectional area of the microcapsules fitted well to the theoretical equations, and the time constants determined as the fitting parameters were discussed in terms of the force constant relaxation and the size relaxation.     

Development of an efficient and safe process for a grignard reaction via reaction caloremetry

A Grignard reaction of reactantA and phenyl magnesium chloride is used to make a pharmaceutical intermediate at the production scale. The elimination of protecting groups onA was proposed as a means to reduce synthesis costs. This new synthesis route, however, had process efficiency and safety issues associated with it: (1) build-up of unreactedA in the reactor, (2) influence ofA's particle size on the reaction rate, (3) the sensitivity of the reaction rate to the reaction temperature and to the (changing) solvent composition, and (4) the highly exothermic nature of the reaction.The Mettler RC1 Reaction Calorimeter was used to quantify the influence of solvent composition, temperature, and particle size on the reaction rate. Results indicated a dramatic effect of solvent composition and reaction temperature on the reaction rate; for example, over a temperature range of just 30°C, the reaction time decreased from more than a day to just a few minutes. At such high reaction rates, the vessel jacket could not remove the reaction heat sufficiently and the internal temperature rose adiabatically.These results were used to make process design and operation recommendations for safe and efficient plant operation with this modified Grignard reaction system.The authors would like to thank the following for their assistance in this work: E. Daugs for preparing the Grignard reagents, K.L. Gonzales for her help in running the experiments and in the subsequent data work-up; P.M. Russell for his assistance in the design of the slurry addition assembly, and K. Chritz and J. Engel for performing the HPLC analyses of the samples.     

Synthesis of polyurethane acrylate oligomers based on polybutadiene polyol

Polyurethane acrylate oligomers (PUA) were prepared by a competitive reaction of 4,4′-dicyclohexyl methane diisocyanate (H₁₂MDI) with hydroxy terminated polybutadiene (HTPB) and hydroxyethylacrylate (HEA). Kinetic models were established for noncatalytic and catalytic systems, and the reaction constants were calculated using a numerical method. The evolution of the noncatalyzed and catalyzed reactions were analyzed, respectively, by SEC and FTIR. Comparing the reactivities of HTPB and HEA, as well as other small molar mass model alcohols, the HTPB showed the higher reactivity. HTPB is 700 times more reactive than HEA at 80°C. This high reactivity was analyzed as a result of lower concentration of hydrogen bonds in bulk HTPB. The activation energy of the noncatalyzed and catalyzed reactions were found to be, respectively, 56.98 and 45.16 KJ/mol. The structures of the PUA synthetized in one-step or two-step process were analyzed and discussed using a gelation model and the kinetic data obtained. © 1996 John Wiley & Sons, Inc.     

镁离子存在下乙醇-水混合溶液中碳酸钙结晶行为的研究

通过对不同反应体系中合成样品的物相及镁含量变化规律的分析, 认为水溶液中碳酸钙的结晶遵循溶解重结晶机理, 乙醇-水溶液中则以聚集重构为主, 碳酸根阴离子的溶剂化作用对碳酸钙的沉积产生显著影响. 采用XRD, IR等手段对醇水混合溶液中合成的碳酸钙样品进行分析, 认为形成了含镁方解石及具有类白云石结构的过渡相同时存在的混合物相, 醇水溶液中含镁方解石趋于白云石化.     

甲基环己基二氯硅烷合成工艺的研究

研究了在常压和无光照的情况下由环己烯和甲基二氯硅烷合成甲基环己基二氯硅烷的工艺，着重研究了合适的催化剂和助催化剂对氢硅加成反应的影响，并就反应液温度和反应时问对反应产物的影响进行色谱跟踪，研究显示反应过程可由反应液温度或反应时间来控制。该过程生产设备简单、操作简便、收率高。