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排序方式: 共有441条查询结果,搜索用时 234 毫秒
81.
Synthesis and characterization of quaternary PtRuIrSn/C electrocatalysts for direct ethanol fuel cells 总被引:1,自引:0,他引:1
K. Fatih V. Neburchilov V. Alzate R. Neagu H. Wang 《Journal of power sources》2010,195(21):7168-10631
To find a more durable anode with high performance for direct ethanol fuel cells (DEFCs), the present study investigates a series of quaternary electrocatalysts, Pt30Ru30Ir40−xSnx/C (wt.%), for the ethanol electro-oxidation reaction (EOR). The carbon-supported Pt30Ru30Ir40−xSnx/C electrocatalysts were prepared by a known impregnation-reduction (borohydride) method. The microstructure and chemical composition were determined by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The activity of the electrocatalysts for EOR was compared to commercial Pt67Ru33/C (HISPEC5000) using linear sweep voltammetry (LSV) based on similar Pt loading. The results of this study show that electrocatalyst composition with 10 and 20% Ir (wt.%) exhibit higher electrocatalytic activity than the commercial PtRu electrocatalyst. The single fuel cell testing at 90 °C comparing Pt30Ru30Ir40−xSnx/C to commercial Pt67Ru33/C and Pt83Sn17/C anodes showed an enhancement of Pt activity (normalized to Pt loading) in the following order: Pt30Ru30Ir10Sn30 > Pt30Ru30Sn40 ≥ Pt30Ru30Ir40 ≥ Pt83Sn17 > Pt67Ru33. After a long-term performance test, the activity changed to the following order: Pt30Ru30Ir10Sn30 > Pt30Ru30Ir40 > Pt30Ru30Sn40 > Pt83Sn17 > Pt67Ru33. Pt30Ru30Ir10Sn30/C exhibited both a higher performance with a specific power density of 29 mW mgPt−1 without O2 backpressure at the cathode and an excellent long-term stability in a DEFC operating at 90 °C. 相似文献
82.
东北是否发育第四纪冰川及其范围、性质与冰期问题,始终没有定论。在对长白山及大兴安岭冰川遗迹厘定基础上,进行了专项调查,并采用地理信息系统(GIS)、遥感(RS)及全球定位系统(GPS)的3S技术,采取钻探测图、孢粉、泥砾粒度与渗透性分析及14C定年等方法,在长白山及大兴安岭发现了冰蚀谷及泥砾堆积等新的冰川遗迹,进一步肯定了两座山地第四纪冰川的存在及其多期性。在小兴安岭首次发现冰蚀岩墙等冰川遗迹,填补了研究空白,证明小兴安岭也曾发育第四纪冰川。综合多种信息,确定长白山与大兴安岭分别有4次冰期和3次间冰期,小兴安岭至少有1次冰期。最后构建了可以与国际对比的冰期序列,重建了区域第四纪冰川环境演化模式:早更新世早期冷干,中晚期偏暖湿; 中更新世早期冷湿,中晚期暖湿; 晚更新世早期冷稍湿,中期暖湿,晚期冷干。 相似文献
83.
C.I. pigment red 170 is an important type of organic pigment. A new type of quaternary ammonium salt containing siloxane group was prepared and then used as a favorable dispersant in the surface treatment of pigment red 170. The quaternary ammonium salt was achieved from the reaction of N-(β-aminoethyl)-γ-aminopropyl-methyl-bimethoxy-silane and 3-chloro-2-hydroxypropyl-bimethyl-hexadecyl ammonium halide in isopropanol, and its structure was characterized by IR and NMR techniques. The flowability, dispersing extent, particle size, and wetting behaviors of pigment were determined and the results showed that a small amount of the above dispersant could bring to the high flowability, good dispersing stability, small particle size and excellent wettability of pigment red 170. We also proposed the scenarios of dispersing process of pigment red 170 based on the information obtained from above characterizations. 相似文献
84.
Hye-Young Ju Mamparambath-Dharman Manju Kyung-Hoon Kim Sang-Wook Park Dae-Won Park 《Journal of Industrial and Engineering Chemistry》2008,14(2):157-160
The synthesis of cyclic carbonate from butyl glycidyl ether (BGE) and carbon dioxide was performed in the presence of quaternary ammonium salt catalysts. Quaternary ammonium salts of different alkyl group (C3, C4, C6 and C8) and anions (Cl−, Br− and I−) were used for this reaction carried out in a batch autoclave reactor at 60–120 °C. The catalytic activity increased with increasing alkyl chain length in the order of C3 < C4 < C6. But, the quaternary ammonium salt with longer alkyl chain length (C8) decreased the conversion of BGE because it is too bulky to form an intermediate with BGE. For the counter anion of the tetrabutyl ammonium salt catalysts, the BGE conversion decreased in the order Cl− > Br− > I−. The effects of carbon dioxide pressure and reaction temperature on this reaction were also studied to better understand the reaction mechanism. 相似文献
85.
Attempts to elaborate the best organized cationic self-assembled monolayers (SAMs) with sulfur derivatives containing potentially bactericidal quaternary ammonium salt moieties have been performed on gold with the final aim to obtain contact-active antibacterial surfaces. Four molecules bearing two hydrocarbon spacers with different lengths between the sulfur atom and the quaternized nitrogen atom, and two different terminal semi-fluorinated alkyl chains have been synthesised and used in view to evaluate their capacity for leading to the highest densities and the highest organization of potentially active molecules on the metal surface. The formation and quality of SAMs characterized by X-ray photoelectron spectroscopy, Internal Reflexion Infra Red Imaging, contact angle and blocking factor measurements depend on the lengths of both the hydrocarbon spacer and terminal perfluorinated chain. 相似文献
86.
The preparations of quaternary ammonium compounds from various tertiary amines and the (environmentally friendly) alkylation
agent dimethyl carbonate were carried out. The effects of reaction temperature, reaction time, material mol ratio and solvent
dosage on quaternization were examined, and the optimum reaction conditions were determined. Under the optimum conditions,
the conversions of mono-alkyl tertiary amines could attain over 99%, while the conversions of di-alkyl tertiary amines reached
over 95%. Moreover, a series of quaternary ammonium salts with new counterions (HCO3, CH3COO, CH3CH2COO, CH3CH(OH)COO) were synthesized by the hydrolysis of methyl carbonate quaternary ammonium salts or by ion exchange reaction of
methyl carbonate quaternary ammonium salts with corresponding acids. 相似文献
87.
通过对安阳市第四系各类钻孔的搜集,基本查明了第四系在区内的分布、规模、特征、成因;该区的第四系堆积物,除分布于丘陵地区外,还广布于区内东半部的冲积平原,其岩性岩相变化大,厚度由西向东逐渐变厚,层次由多层到单层,颗粒逐渐变细,成因由冲洪积→冲积→坡冲积的变化规律,同时也反映了由老到新,坡冲积堆积范围由大到小,冲积范围由小到大的演变过程。 相似文献
88.
钻井液用阳离子甲基葡萄糖苷 总被引:1,自引:0,他引:1
针对甲基葡萄糖苷在钻井液中加量大、抗温性较差、抑制性有待提高等缺陷,在甲基葡萄糖苷分子上引入季铵盐的结构,合成了阳离子甲基葡萄糖苷CMEG。实验结果表明,合成出的CMEG具有很好的表面活性和润滑性,5%CMEG水溶液的表面张力为30.9 mN/m,摩阻系数仅为0.16(与油基钻井液相当),有助于提高采收率和加快钻井速度;具有优异的抑制页岩水化膨胀(相对回收率高达99.01%)和抗高温(150℃)的能力,且配伍性较好,能与其他处理剂产生协同作用。CMEG性能都优于甲基葡萄糖苷,预计在钻井液中具有极好的应用前景。 相似文献
89.
Solid-liquid equilibrium of quaternary system Cd<'2+>//Cl<'->, SO<,4><'2->, NO<,3><'->-H<,2>O at 298 K was studied by means of an isothermal solution saturation method. Experimental results indicate that there are three univariaut curves BE, AE and CE, one invariant point E and three crystallization fields in the quaternary system. The quaternary system belongs to a simple type, and there are no double salts or solid solution existing. The crystallization zones of equilibrium solid phases are CdCl2·5/2H2O(AFB field),3CdSO4·8H2O(AFC field)and Cd(NO3)2·4H2(BEC field),respectively. The composition of the invariant point is CdCl<,2>, Cd(NO<,3>)<,2>, CdSO<,4> and H<,2>O and the contents of which are 17.02%, 45.50%, 4.52% and 32.96%, respectively. The physico-chemicai properties of solution in the quaternary system show regular changes along with the increased cadmium concentration. The results indicate that Cd(NO<,3>)<,2> possessed the highest solubility among those three salts, which means a strong transfer of Cd ion and a high pollution risk of soil environment. And the solubility of CdSO<,4> would be restrained as the salts existing together. 相似文献
90.