Corrosion-resistant lightweight metallic bipolar plates for PEM fuel cells

Corrosion resistant treated metal bipolar plates with higher rigidity and electrical conductivity than graphite were developed and tested for PEM fuel cell applications. Six replicas of single cells were used three of which were made of graphite composites bipolar plates and the other three of the treated metallic plates. A Membrane Electrode Assembly (MEA) with 5.55 cm² active electrode areas, 0.3 mg cm^–2 Pt loading and Nafion membrane 115 was fitted to each cell and operated under identical conditions. The experimental testing was conducted at room temperature (20 °C). The average value of the data obtained for the three graphite cells was plotted. Similarly, the average value of the data obtained for the three treated metal cells was plotted on the same graph for comparison. Generally, the treated metal bipolar plate provided at least 12% saving in hydrogen consumption in comparison to graphite. This is attributed to the lower bulk and surface contact resistance of the metal used in this study in relation to graphite. The results of lifetime testing, conducted at room temperature under variable loading showed no indication of power degradation due to metal corrosion for at least 1500 hours.     

重庆建筑与风土人情

通过对重庆两个旧居住区的调研,探讨山城建筑艺术与特点,以及具有民俗个性的生活空间,为今后的重庆建筑发展及旧区保护等问题的解决,提供素材。     

复射影空间中的整体Pinching定理

本文讨论了复射影空间的偶维紧致全实极小于流形,得到了几个关于第二基本形式模的平方的整体pinching定理,进而得到了使该类子流形成为全测地子流形的几个充分条件。     

一类广泛的耦合Schrodinger-klein-Gordon方程组的初边值问题

本文考虑一类非线性耦合Schrdinger—klein—Gordon方程组的初边值问题,采用Galerkin方法与紧致性原理,在较弱的条件下,证明了该问题整体解的存在性。     

大米安全度夏的试验报告

选用武汉地区三种不同水分的大米,分别采用不同的储藏方式,对其进行了安全度夏的试验。摸索出被储藏大米的物理特性、生化品质、微生物的污染等情况。对不同水分的大米在武汉地区安全度夏的技术措施提出建议。     

正态模糊随机过程的基本性质

正态F随机过程是在理论和应用中都很重要的特殊F随机过程。本文在文[4]的基础上,继续研究正态F随机过程的基本性质,并且把讨论范围扩充到了复F随机过程的情形。引入了正态复F随机过程的概念,讨论了它们的若干基本性质。     

浸胶帆布经向刚度影响因素分析

综合分析各方面因素对浸胶帆布经向刚度的影响。结果表明纤维材料的种类、线密度和捻度,帆布织物的材质和结构,浸胶工艺中的附胶量、温度、浸胶速度、循环风机频率、浸渍张力和柔化器,测试中的实验室外部环境、放置时间和操作方法均会对浸胶帆布的经向刚度产生影响。实际生产中可以采取相应措施来控制经向刚度的大小,以满足客户需求。     

新型PVC/OHA/D2EHPA基膜增强型聚合物包容膜的制备及性能评价

为解决聚合物包容膜(PIM)传输效率低的问题。制备了一种以聚氯乙烯(PVC)为基体,包含固液两种载体的基膜增强型PIM。以N-羟基正辛酰胺(OHA)作为新型载体固定于基膜孔道内,利用其与有机萃取剂二(2-乙基己基)磷酸酯(D2EHPA)的协同作用,实现高效传质。对制备的基膜增强型PIM进行SEM、EDS、FTIR、XPS、力学性能以及传质性能考察与表征。结果表明,载体配比为22% OHA+17% D2EHPA的基膜增强性PIM对50 mg/L的Zn_²⁺的10h回收效果最佳,萃取率和反萃率分别为59.86%和51.10%。5个周期的运行实验中,基膜增强型PIM初始传质通量为587.36 mg.m_^-2.h_^-1,约是仅包含液相萃取剂PIM传质通量(312.64 mg.m_^-2.h_^-1)的2倍。5个循环周期结束后,基膜增强型PIM传质通量仍高于仅包含液相萃取剂PIM传质通量。     

Pt-modulated Cu/SiO2 catalysts for efficient hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol

Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene car-bonate (EC),a key step in the indirect conversion of CO2 to methanol.However,a high H2/EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved.Herein,we fabricated a series of Pt-modulated Cu/SiO2 catalysts and investigated their catalytic perfor-mance for hydrogenation of EC in a fixed bed reactor.By modulating the Pt amount,the optimal 0.2Pt-Cu/SiO2 catalyst exhibited the highest catalytic performance with ～99％ EC conversion,over 98％ selectiv-ity to ethylene glycol and 95.8％ selectivity to methanol at the H2/EC ratio as low as 60 in feed.In addition,0.2Pt-Cu/SiO2 catalyst showed excellent stability for 150 h on stream over different H2/EC ratios of 180-40.It is demonstrated a proper amount of Pt could significantly lower the H2/EC molar ratio,promote the reducibility and dispersion of copper,and also enhance surface density of Cu+ species.This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice.Meanwhile,a relatively higher amount of Pt would deteriorate the catalytic activity,which could be due to the surface coverage and aggregation of active species.These findings may enlighten some fundamen-tal insights for further design of Cu-based catalysts for the hydrogenation of carbon-oxygen bonds.     

APTES改性ZIF-L/PEBA混合基质膜强化渗透汽化分离苯酚研究

渗透汽化(PV)膜分离是一种高效节能、无污染的化工分离技术,在有机废水处理领域的应用潜力巨大。以3-氨丙基三乙氧基硅烷(APTES)改性二维ZIF-L(AZLs),将其引入聚醚嵌段酰胺(PEBA)内制备AZLs/PEBA混合基质膜,用于分离水溶液中的苯酚。系统表征了所制膜的微结构与物化特性,考察了APTES添加量、AZLs填充量、操作温度、料液浓度等对膜分离性能的影响。结果表明：AZLs均匀分散在PEBA基质中,表明两者具有良好的界面相容性。AZLs的加入使得膜疏水性增强而表面自由能降低,从而提高了PEBA膜的选择性。当分离80℃、1000 mg/kg苯酚水溶液时,AZLs/PEBA膜总通量可达2046 g/(m²·h),分离因子为25.4,并且具有一定的稳定性。所制AZLs/PEBA混合基质膜在含酚废水处理方面具有应用前景。