Effect of ZnO on Cu/ZnO/Al_2O_3 catalysts for methanol synthesis

[中文文摘]用高速碰撞共沉淀法制备m(CuO) /m(ZnO) /m(Al2 O3 )比分别为 60 /3 0 /1 0和 3 0 /60 /1 0的 1 #和 2 #催化剂 ,结果表明高ZnO的 2 #催化剂活性较好 ,分散度较大。XPS测试表明 2 #催化剂表面ZnO吸附的中间体 (CHx 或CHxO)较多且表面的Cu+1浓度较高 ,从而促进CO加氢合成甲醇的活性。[英文文摘]Cu/ZnO/Al_2O_3 catalysts with ratios of 60/30/10 and 30/60/10 have been prepared by high speed collision coprecipitation method. The performance of the catalyst with the higher ZnO content shows the higher activity in methanol synthesis. The characterization results indicated that the catalyst with the higher ZnO content has higher dispersion. On the surface of the higher ZnO content catalyst, there was more Cu+1 and more intermediate (CH_x and CH_xO) adsorpted. It is beneficial for the CO hydrogenating to produce methanol

化学信息学网络考试系统的构建

在WindowsNT 4 .0服务器建立化学信息学的Access试题数据库 ,使用ASP编写网络考试系统 ,供学生在Internet上使用浏览器进行在线考试。该系统安全可靠、应用范围广 ,是发展远程教育的重要工具

铝氧原子簇负离子的激光产生与结构

二元以至多元原子簇(包括铝氧原子簇)的产生与研究是当前十分活跃的领域.最近,我们在自制的装置上,以功率密度达10~8W·cm~(-2)的脉冲激光束(波长532nm)在10_4~-Pa 的真空中溅射AlN 样品时,在实验记录的正负离子质谱中出现的几乎都是铝原子簇离子;而当我们选择α-Al_2O_3为样品时,则观察到了一系列质量分布很广的二元铝氧原子簇负离子,如图1所示.图1的飞行时间质谱是连续100次记录的数据叠加的结果,图中各Al_nO_m~-分别以(n,m

理科化学系列

厦门大学校内自建数据

The Key Techniques in Developing Homepage of Xiamen University

厦门大学主页具有丰富多采的装饰图案和新颖的动感画面、版面设计美观多样.文中介绍制作厦门大学主页使用的技术.这些技术的综合，使得用户浏览主页时交互性强，操作方便，视觉效果良好.The Homepage of Xiamen University has been well known For its beautiFul and diversiFied having rich and colorFul decorations and vivid animated images.This paper summarizes some key techniques in the Homepage developing, such as basic HTML, Java language, JavaScript, CGI programs, image map, Frames, animated GIF Files and images compression.The user can browse Homepage of Xiamen University more conveniently and interactively with the combination above techniques

Geometry Prediction For Coalescence of Fullerenes

采用分子图形软件编辑设计出C60的可能聚合构型（C118，C128，C138，C178及Td，d6d，d5d和d2d点群的C120分子），对它们进行分子力学优化，并计算出C120分子的各种聚合形式力学能量值，从中可看出以单链连接的哑铃状结构的C60二聚体稳定存在的可能性很少。而经离解重组的笼状结构体系能量较低。文章还进一步讨论并描绘了C60聚合过程中可能经历的结构重组过程与机理。Abstract The coalescence model of Fullerenes (C118, C128, C138, C178)and C120 isomers(Td, D6d, D5d, D2d )have been designed with the molecular graphics software.AFter the optimization with molecular mechanics, the energies of the C120 isomers have been listed.The dumbbell-shaped C120 is not stable yet and the energies of lagger, higher order Fullerenes dramatically reduce according to the calculation results.We propose the coalescence structure may be diFFerent iF the cages remain intact during the photO polymerization.In addition, the growth processes For D5d C120 isomer were also discussed.国家自然科学基

Study on the Bond Valance Parameters Related to Lanthanoid

[中文文摘]根据镧系元素络合物的晶体结构数据确定了单价键长R0的镧系收缩效应,并对已有的键价参数进行了系统的修订.建立了Ln-O键的R0对原子序数N在普适参数B=0.037nm下的线性方程R0(nm)=0.2879-0.00132N.用不同参数进行键价和的计算并对结果进行了对比和讨论,最后展望了相关研究的前景.[英文文摘]Based on the crystal structure data of the lanthanide complexes, lanthanide contraction of the single valance bond length R0 for Ln-O bond is confirmed. The R0 values with B=0.037 nm were re determined systematically as described by the linear equation R0(nm)=0.2879-0.00132N, where N is the atomic number of lanthanide. Using the parameters suggested by Brown O′Keeffe and thepresent authors, the bond valance sums for Ln(III) in some organometallic compoumds were calculated and discussed in detail.Prospects for the further studies in the line of bond valence parameters were bridfly presented

A density functional study of CO2 adsorption on the (100) face of Cu(9,4,1) cluster model

The adsorption modes of inert CO2 on the (100) face of Cu(9,4,1) cluster model have been studies by the Slater DFT code of the Amsterdam density; functional (ADF) program. The side-on adsorption mode with near linear CO2 lying at the short bridge site has the highest binding energy of 26.31 kJ mol(-1). The binding energies of CO2 in similar geometry on the cross bridge, hollow, and on-top sites vary from 19.66 to 21.8 kJ mol(-1). The investigation also revealed that a number of CO2 bent modes with O-C-O angles equal to approximate to 150 degrees can coordinate with the surface with binding energies ranging from 9.66 to 23.56 kJ mol(-1). Further calculations indicated that to cause the CO2 molecule to bend to approximate to 150 degrees, there is negative charge transferred from the copper cluster to the CO2 molecule. (C) 1997 Elsevier Science B.V