聚乙烯醇膜的阻醇及导电性能(Ⅱ)戊二醛交联聚乙烯醇膜

为提高直接甲醇燃料电池(DMFC)用膜的阻醇性能，采用在渗透蒸发领域广泛使用且具有良好分离效果的聚乙烯醇(PVA)为主要材料，制备了戊二醛(GA)交联PVA膜，考察了此类膜的阻醇及质子导电能力。PVA(GA)膜的阻醇效果较目前在DMFC中广泛使用的Nation膜有显著提高，但其自身不具有质子导电能力，需外加电解质溶液以提高其电导率。     

In situ FTIR spectroscopy on rhodium-exchanged NaX zeolite with different metal dispersion during syngas reaction

In situ FTIR spectroscopy has been applied to study the reason of the different selectivity behaviour of rhodium in the CO hydrogenation reaction in dependence on the different particle size. Several forms of molecularly adsorbed CO are observed, such as linearly- and bridgedbonded CO on metallic rhodium as well as dicarbonyl species with Rh(I) centres formed by oxidation of Rh(0) with protons in presence of CO. Furthermore, non-reactive formate, acetate, and carbonate species are produced as side products of the reaction. The higher selectivity to oxygenates, particularly to methanol, is explained by the existence of multiple-bonded CO present only on small rhodium crystallites. The multiple-bonded CO formed at low temperatures is converted at higher temperatures to the highly reactive formyl species, which is hydrogenated to methanol.     

SAPO-34/SiO_2催化甲醇制烯烃

采用水热法合成了SAPO-34分子筛,并用X射线粉末衍射仪和扫描电子显微镜对SAPO-34分子筛的结构进行了表征,同时探讨了黏合剂种类、甲醇分压、催化剂粒径和硅源等对SAPO-34分子筛催化甲醇制烯烃(MTO)反应性能的影响。实验结果表明,在MTO反应中,三烯(乙烯、丙烯和丁烯)选择性在反应初期存在明显的诱导期;以S iO2为黏合剂合成的SAPO-34/S iO2催化剂不但可缩短MTO反应的诱导期,三烯选择性也较未添加黏合剂或以A l2O3为黏合剂时高1~2个百分点;且当催化剂活性明显下降时,三烯选择性下降的幅度较小。催化剂粒径、甲醇分压及硅源对催化剂的诱导期也有明显的作用。在甲醇分压低于19kPa、催化剂粒径0.25~0.38mm、S iO2为黏合剂、硅酸四乙酯为硅源时,SAPO-34/S iO2催化剂的MTO性能明显提高。     

分离有机/有机混合物的PVA、CA系列膜及其渗透汽化性能研究(Ⅱ) 成膜条件对渗透汽化性能的影响

用溶剂完全蒸发法制备了PVA复合膜 .经对MTBE/MeOH混合物的分离实验得到了PVA复合膜的最佳成膜条件 ,即 :铸膜液中PVA、马来酸浓度分别为 7%、3% ,热处理温度130～ 15 0℃ .在 1%～ 2 %丙酮水溶液中浸泡处理 4～ 8h ,CTA中空纤维RO膜被改性成渗透汽化膜 .CTA中空纤维膜的分离性能优于其它醋酸纤维素系列膜 ,PVA/CA复合膜的性能优于PVA/PAN复合膜和CA/PAN复合膜     

The relationship between denitrifying bacteria and methanogenic bacteria in a mixed culture system of acclimated sludges

The interaction between denitrification and methanogenesis, with methanol functioning as an electron donor, has been examined through usage of a mixed culture system of denitrifying sludge and methanogenic sludge in an anaerobic bioreactor. Competition for methanol between these two kinds of biocommunity could not be observed, whereas methanogenesis was suppressed as long as nitrate and nitrite were made available in the mixed system. The inhibition of methanogenesis in the methanogenic sludge caused by nitrogen oxides was studied. The redox potential (E_h) of the culture was monitored and/or controlled for the sake of characterizing the behavior of the biocommunities. An addition of nitrite elevated the E_h of the culture less than nitrate did. Nitrite addition, however, exerted a stronger inhibitory effect on methanogenesis as compared to nitrate at the same concentration. The influence of redox potential on the methanation of methanol was examined by using a methanogenic sludge in the E_h-stat batch culture. The hypothesis that the inhibitory effect being expressed by the nitrogen oxides is not simply attributed to an elevation of the redox potential of the culture is supported by the experimental results. The toxic effect of the nitrogen oxides themselves could also have possibly contributed significantly.     

甲醇与碳酸二甲酯共沸液的分离研究进展

综述了DMC-CH_3OH二元共沸液的各种分离方法。讨论了共沸精馏和萃取精馏的工艺流程。     

甲醇氧化制甲醛铁钼催化剂的研究

采用共沉淀法制备甲醇氧化制甲醛无载体铁钼催化剂,并考察了催化剂制备老化条件、焙烧温度、外型尺寸以及活性测试反应温度、空速对催化剂性能的影响。该催化剂在280~300℃、气空速7000 h-1~8000 h-1、进料φ(甲醇)为5.5%的下,可获≥98%的甲醇转化率,≥92%的甲醛选择性和≥90%的甲醛产率。催化剂活性高,强度好,性能稳定。     

Electron transport in direct methanol fuel cells

A three-dimensional (3D), two-phase, isothermal model of direct methanol fuel cells (DMFCs) was employed to investigate effects of electron transport through the backing layer and the land in bipolar plates. It was found that the electronic resistance of the backing layer, affected by backing layer electronic conductivity, backing layer thickness and flow channel width, played a relatively important role in determining the current density distribution and cell performance. In order to ignore the electron transport effect on the average current density, the minimum electronic conductivity of the backing layer has to be 1000 S m⁻¹, with the relative error in the average current density less than 5%, under the given conditions.     

甲醇合成化学平衡常数的测定与推算

以低压法(5MPa)甲醇合成为背景,建立了气相法甲醇合成化学平衡常数的实验测定系统,测定了不同温度和压力下,CO、CO_2同时加H_2合成CH_3OH反应的平衡组成及化学平衡常数K_p,同时以实验结果为依据,对K_p的理论推算进行了探讨,其中对文献中计算以逸度表示的平衡常数K_f的各种方程进行了比较。结果表明,基于Cherednichenko的K_(f,Ⅰ)和Bissett的K_(f,Ⅱ),采用修正的SRK方程,对K_p的推算取得了满意的结果。     

“十一五”我国石油替代和再生能源部分产品发展分析

能源多元化对保障国家能源安全,紧跟世界能源发展趋势,及时转变能源发展战略的意义重大。分类讨论替代燃料,分析其发展态势和需要的支撑条件。