Cu-Mn氧化物催化N_2O直接分解性能

分别以Cu(NO_3)_2·3H_2O和50%Mn(NO_3)_2水溶液为铜源和锰源,K_2CO_3为沉淀剂,采用沉淀法和共沉淀法制备单一Cu、Mn氧化物催化剂和Cu-Mn-O复合氧化物催化剂,用于催化N_2O直接分解反应,并利用N_2物理吸附-脱附、XRD、FT-IR和TPR等进行表征。结果表明,单一Cu和Mn氧化物分别以体相CuO和Mn2O_3物相形式存在,Cu-Mn-O复合氧化物中除形成CuMn_2O_4尖晶石物相外,还有一定量小晶粒CuO,较单一氧化物具有更加优异的还原性能,表现出较高的催化N_2O直接分解活性。在空速10 000 h~(-1)和N_2O体积分数0.1%条件下,Cu-Mn-O复合氧化物催化剂可在440℃催化N_2O完全分解,分别较单一Cu和Mn氧化物催化剂降低了40℃和60℃。     

尖晶石型复合氧化物光催化研究进展

磺扼要叙述了尖晶石型复合氧化物(AB2O4)作为光催化剂的研究进展.包括结构,机理,制备,改性和研究现状.强调了结构和性能之问的关系并对其研究方向提出了自己的见解.     

含铜半导体氧化物的光催化应用进展

应用半导体材料光催化降解污染物和光催化分解水制氢是近几十年来的材料研究热点之一。从拓展光催化材料种类的角度出发,本文对含铜半导体氧化物的基本性质、制备方法及其在光催化方面的应用情况进行了综述。所涉及的氧化物包括含一价铜的氧化亚铜和铜铁矿类复合氧化物,以及含二价铜的氧化铜和尖晶石类复合氧化物。指出将含铜p型半导体氧化物与n型半导体材料复合,制备p-n异质型复合氧化物是有前途的研发方向。     

燃烧快速制备铁酸铋复合氧化物及光催化研究

本文采用新型燃烧剂抗坏血酸,燃烧法快速制备铁酸铋的复合氧化物.经XRD考察硝酸铁和硝酸铋物质量之比对复合氧化物的影响,电镜表征复合氧化物的形貌、BET表征复合氧化物的比表面积、紫外和红外表征复合氧化物的吸光性能.以甲基橙为目标降解物对铁酸铋的复合氧化物进行光催化研究.本文考察了复合氧化物类型、催化剂用量、溶液酸度、双氧水用量、光照时间对光催化效果的影响.最佳光催化条件为催化剂用量为0.01 g/L,pH值为5,双氧水用量为60 mL/L.BiFeO3在紫外和可见光下均有较好的光催化效果,Bi2Fe4O9只在紫外光下有较好的光催化效果.     

尖晶石型ZnCo2O4电极材料的合成及其电化学性能研究

水热法加煅烧处理合成了尖晶石型ZnCo2O4电极材料,考察反应时间、反应温度对目标材料的影响.利用XRD、SEM、CV以及恒流充放电测试等手段对目标材料进行结构表征和性能测试.结果表明,在反应时间为7 h、反应温度为120℃下合成的多孔ZnCo204褶皱微球形状规则,平均直径为10～12 μm.在此条件下得到的ZnCo...     

钛铝复合氧化物催化材料的研究进展

钛铝复合氧化物催化材料的发展为研究选择加氢反应、氧化脱氢和加氢脱硫等化工工艺提供了新途径。钛铝复合氧化物由于制备简单、可操作性强等优点,引起了人们的广泛重视。本文综述了钛铝复合氧化物催化材料的制备研究进展,同时简要概述了Ti O2-Al2O3复合氧化物材料在酯化反应、选择加氢、催化选择还原NO、氧化脱氢、甲醇合成、光催化反应、加氢脱硫等方面的应用。简要比较了几种方法制得的Ti O2-Al2O3复合氧化物,提出了该复合材料在目前研究应用中存在的问题及解决途径,并展望了其应用前景。     

纳米尖晶石型复合氧化物的合成及应用

本文综述了纳米尖晶石型复合氧化物的合成方法，包括物理合成法和化学合成法。主要介绍了化学合成法，如：沉淀法（直接沉淀法，均相沉淀法，共沉淀法），溶胶－凝胶法，水热法，化学气相沉积法和微孔液法，并比较了不同合成方法的优缺点。同时介绍了纳米尖晶石型复合氧化物的应用现状，发展前景，它可以作为颜料，磁性材料，催化材料，隐身材料等广泛应用于生产和生活的各领域中，是一类重要的无机材料。     

ZnYb2O4稀土复合氧化物合成与结构解析

报道了以流变相-先驱物法制备稀土复合氧化物ZnYb2O4的软化学方法。首先用流变相法合成草酸盐先驱物ZnYb2（C2O4）4,然后用DTA和TG研究了先驱物在空气申的热分解过程;用X射线粉末衍射和IR光谱表征了热分解固体产物;通过从头算法对热分解固体产物的晶体结构进行了解析。结构分析表明该化合物为尖晶石结构。     

稀土氧化物对反应烧结合成镁铝尖晶石的影响

以分析纯MgO(粒度<5 um)和活性仅α-Al2O3微粉(粒度<5 um)为主要原料,分别添加不同量的4种稀土氧化物粉末(Y,,2O3、La2O、Nd2O3和CeO2),共混4 h后,在100 MPa下压制成φ30 mm×20 mm的试样,经110℃干燥6 h后,分别于1 100、1 200、1 300、1 400、1 500和1 650 ℃保温3 h烧成.借助DSC、XRD、SEM和能谱分析研究稀土氧化物对反应烧结合成镁铝尖晶石的影响.结果表明:(1)添加稀土氧化物降低了镁铝尖晶石'的结晶温度,促进了尖晶石的晶粒发育;(2)添加3%Nd2O3的试样经1 650℃保温3 h制备出相对密度为92%的镁铝尖晶石;(3)稀土氧化物促进镁铝尖晶石致密化的机理不同:Y2O3和Nd2O3在试样中形成复杂氧化物活化了晶格,而La2O3和CeO2在试样中主要是形成液相,从而促进了镁铝尖晶石的烧结致密化.     

M_(0.5)Co_(2.5)O_4(M=La,Ce,Pr,Nd)尖晶石型复合氧化物催化剂催化分解N_2O性能

采用共沉淀法制备了M_(0.5)Co_(2.5)O_4(M=La,Ce,Pr,Nd)钴基尖晶石型复合氧化物催化剂,运用XRD、SEM、H_2-TPR和O_2-TPD-TG等对催化剂物化性能进行表征,并在固定床微型反应器中评价催化剂催化分解N_2O性能。结果表明,稀土金属掺杂改性的钴基尖晶石型复合氧化物催化剂粒径明显减小,比表面积增加,氧化还原性能得到改善,催化分解N_2O活性提高,其中,M_(0.5)Co_(2.5)O_4催化剂催化分解N2O温度低,T10和T95分别为342℃和499℃。     

Reactions of adenine with ethylene oxide and propylene oxide

Reactions leading to thermostable polyetherols containing purine rings were studied. Products of reaction of adenine and an excess of the oxiranes were analyzed by proton nuclear magnetic resonance and infrared spectroscopies. The physical properties of some of the products were determined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 489–497, 2002     

Vanadium oxide surfaces and supported vanadium oxide nanoparticles

The information obtained from the characterization of vanadium oxide single crystal surfaces is related to the study of vanadia nanoparticles supported on silica and alumina thin films, model systems for the so-called “supported monolayer vanadia catalysts”. It is found that these particles have properties similar to V₂O₃ surfaces, where the topmost V ions are involved in vanadyl groups and have a 5+ oxidation state. A vibrational spectroscopy investigation combined with DFT calculations show that the accepted interpretation of vibrational spectra from vanadia catalysts must be revised.     

Electronic structure of graphite oxide and thermally reduced graphite oxide

We present the electronic structure evolution from graphite oxide to thermally reduced graphite oxide. Most functional groups were removed by thermal reduction as indicated by high resolution X-ray photoelectron spectroscopy, and the electrical conductivity increased 6 orders compare with the precursor graphite oxide. X-ray absorption spectroscopy reveals that the thermally reduced graphite oxide shows several absorption peaks similar to those of pristine graphite, which were not observed in graphite oxide or chemically reduced graphite oxide. This indicates the better restoration of graphitic electronic conjugation by thermal reduction. Furthermore, the significant increased intensity of Raman 2D band of thermally reduced graphite oxide compared with graphite oxide also suggests the restoration of graphitic electronic structure (π orbital). These results provide useful information for fundamental understanding of the electronic structure of graphite oxide and thermally reduced graphite oxide.     

Processing and properties of oxide matrix/oxide fibre composite

Abstract

An all-oxide composite was fabricated. Single crystal alumina fibres were coated with a carbon/zirconia slurry, dried, and uniaxially aligned by winding. Matrix material, alumina with 5 vol.-% unstabilised zirconia added, was tape cast on top of the fibres. Pre-pregs were cut, stacked, and laminated to cross-ply material. Final sintering was done by hot isostatic pressing. A heat treatment was added to remove the carbon and create a porous zirconia interphase. Flexure strengths around 200 MPa were obtained for composites at room temperature while a strength of 124 MPa was recorded at 1200°C. The mechanical properties and non-brittle behaviour was sustained after aging at 1400°C for 1000 h in air.     

环氧乙烷环氧丙烷嵌段共聚醚应用进展

介绍了环氧乙烷环氧丙烷嵌段共聚醚的生产技术和应用领域,重点叙述了烯丙醇类环氧乙烷环氧丙烷共聚醚在减水剂行业中的应用。     

Copolymerization of ethylene oxide and propylene oxide by anhydrous potassium hydroxide

Ethylene oxide and propylene oxide have been copolymerized at low temperatures in the presence of anhydrous potassium hydroxide. The monomer reactivity ratios were found to be r(ethylene oxide) = 6.5 and r(propylene oxide) = 0.5.     

Raman and IR studies of surface metal oxide species on oxide supports: Supported metal oxide catalysts

Raman and infrared spectroscopy provide complementary information about the nature of the surface metal oxide species present in supported metal oxide catalysts. This paper reviews the type of fundamental information that is typically obtained in Raman and IR characterization studies of supported metal oxide catalysts. The molecular structures of the surface metal oxide species are reflected in the terminal M=O and bridging M-O-M vibrations. The location of the surface metal oxide species on the oxide supports is determined by directly monitoring the specific surface hydroxyls of the support that are being titrated. The surface coverage of the surface metal oxide species on the oxide supports can be quantitatively obtained since at monolayer coverage all the reactive surface hydroxyls are titrated and additional metal oxide results in the formation of crystalline metal oxide particles. The nature of surface Lewis and Brønsted acid sites present in supported metal oxide catalysts are determined by adsorbing basic probe molecules like pyridine. Information about the behavior of the surface metal oxide species during catalytic reactions are provided by in situ characterization studies. Such fundamental information is critical for the development of molecular structure-reactivity relationships for supported metal oxide catalysts. This paper will be limited to supported metal oxide catalysts containing group V-VII transition metal oxides (e.g., V, Nb, Cr, Mo, W and Re) on several different oxide supports (alumina, titania, zirconia, niobia and silica).