微乳液法制备纳米草酸钆的热解机理的研究

Gd₂O₃∶Tb³⁺ luminescent nanoparticles were prepared by the thermal decomposition of the nanosized oxlate prepared in the reverse microemulsions based on triton X-100 / n-hexyl alcohol, n-octane, and water. From TG-DTA, XRD and FTIR analyses, the mechanism of thermal decomposition of the nanosized oxalate precursor is suggested as follows: Gd₂(C₂O₄)₃·10H₂O → Gd₂(C₂O₄)₃ + 10H₂O, Gd₂(C₂O₄)₃ → Gd₂O₂(CO₃) + 3CO +2CO₂, Gd₂O₂(CO₃) → Gd₂O₃ + CO₂. The kinetic parameters of thermal decomposition reaction-activation energy E of stage 2 and 3 are 194.6 kJ·mol^-1, 110.9 kJ·mol^-1, respectively, using Ozawa method. And the reaction order n is 2.9 and 0.43, respectively, according to the TG curves.     

Thermal Decomposition of Polytetrafluoroethylene Oxide

The thermal degradation of polytetrafluoroethylene oxide has been examined by the isothermal and thermogravimetric methods in the temperature range 450 to 650°C. The main components of the volatile gas are trifluoro-acetyl fluoride, carbonyl fluoride, and tetrafluoroethylene. The thermogravimetric decompositions of polytetrafluoroethylene oxide and of polytetrafluoroethylene have been compared.     

N2O的催化分解研究

N2O是主要的温室气体之一,它在对流层中具有破坏臭氧的作用,因此,N2O的消除越来越引起人们的重视。N2O的直接催化分解是公认的消除N2O污染的最有前景的方法之一,具有操作简单、成本低、不需引入其他杂质、不产生二次污染等特点。本文综述了近年来在N2O催化分解领域广受关注的几类催化剂的最新研究进展,包括金属氧化物催化剂、负载型贵金属催化剂和分子筛催化剂体系,概括了这些催化剂的优点和缺点,介绍了固体催化剂表面N2O催化分解的反应动力学、分子模拟及反应机理。从工业应用角度出发综述了工业生产过程中可能对催化活性造成影响的NOx、O2、H2O和SO2等其他气体对催化剂活性、寿命和稳定性的影响。最后指出了N2O催化分解理论研究及催化剂体系存在的一些问题,并在此基础上对N2O催化分解体系的发展前景进行了展望。     

热分解法制备纳米氧化钕

采用热分解法以2-硝基苯甲酸和硝酸钕为原料制备了纳米氧化钕微粉,利用正交设计对合成条件进行了优化,得出了最佳的合成条件,即原料2-硝基苯甲酸与硝酸钕物质的量比2.5∶1,溶液pH值5.5,反应时间3h、干燥时间8 h,在此条件下制得了平均粒径为15 nm的氧化钕微粉,并利用XRD和TEM对制得的纳米微粉进行了结构表征.     

Crystal Structure and Magnetic Property of Heteronuclear Copper—Lanthanum Carboxylate Complex

ＥｘｐｅｒｉｍｅｎｔａｌＳｙｎｔｈｅｓｉｓａｎｄｅｌｅｍｅｎｔａｌａｎａｌｙｓｉｓＬａＬ3·2Ｈ2 Ｏ (86 0ｍｇ ,2 0ｍｍｏｌ ;ＨＬ =ＣＨ2 Ｃ(ＣＨ3) ＣＯＯＨ)ａｎｄＣｕ(ＮＯ3) 2 ·3Ｈ2 Ｏ (2 4 2ｍｇ ,1 0ｍｍｏｌ)ｗｅｒｅｄｉｓｓｏｌｖｅｄｉｎｔｏ 2 0ｍＬｏｆＨ2 ＯａｎｄａｄｊｕｓｔｅｄｔｏｐＨ 4 1ｗｉｔｈＨＬ (0 1ｍｍｏｌ/ｃｍ3) .Ａｎｅｔｈａｎｏｌｓｏｌｕｔｉｏｎｏｆ 1,10 ｐｈｅｎａｎｔｈｒｏｌｉｎｅ (2 0 0ｍｇ ,1 0ｍｍｏｌ)ｗａｓａｄｄｅｄｉｎｔｏｔｈｅｍｉｘｅｄｓｏｌｕｔｉｏｎｗｉｔｈｓｔｉ…     

Cu-Mn-Ce/γ-Al2O3汽车尾气净化催化材料的合成及性能的研究

采用固定床反应装置，模拟汽车尾气的组成成分，以CO氧化和NH3选择还原NO为探针反应，研究了焙烧温度和焙烧时间等因素对复合金属氧化物催化材料Cu-Mn-Ce-O／γ-Al2O3的催化活性的影响，并考察了该催化剂的抗硫化中毒性能。在本研究条件下，焙烧温度在700℃左右，焙烧时间为2．5h时，催化剂对NO-CO体系中CO的氧化率在76％，以上，对NH3-NO体系中的NO的最佳催化还原率在80％以上。催化剂在3．O％S02／空气气氛中强制中毒后，其在NH3-NO气氛中的最佳反应温度．450℃，同样条件下未中毒催化剂的最佳反应温度为350℃左右，并且催化剂中毒后对NO—NH3的最大转化率没有下降，但是对NO-CO体系的反应活性明显下降，说明该催化剂具有良好的高温活性和抗硫中毒性能。     

堇青石蜂窝陶瓷负载锰氧化物催化分解臭氧性能

为了提高臭氧分解催化剂的实际应用能力,通过采用过渡金属锰氧化物为原料与铝胶混合涂覆到堇青石蜂窝陶瓷载体表面,制备了不同锰氧化物负载的整体式催化剂。 然后在常温常压下考察了整体式催化剂分解臭氧的性能。 通过X射线衍射(XRD)、扫描电子显微镜(SEM)、拉曼(Raman)光谱、X射线光电子能谱仪(XPS)、BET比表面积法和程序升温还原技术(H₂-TPR)对催化剂进行了表征。 研究结果表明,不同锰氧化物催化剂的活性按以下顺序排列:氧化锰八面体分子筛(OMS-2)＞MnO₂＞Mn₂O₃＞Mn₃O₄＞MnO。 相比其它锰氧化物,OMS-2负载的整体式催化剂对臭氧的反应活性最高,这可能归因于OMS-2具有较大的比表面积和较好的还原性能,从而有利于表面氧空位的生成和参与臭氧分解反应。 研究结果为提高堇青石蜂窝陶瓷负载型整体式催化剂应用于臭氧分解的性能提供了理论依据。     

Synthesis of Molybdenum Oxide by Thermal Decomposition of Molybdenum Acetylacetonate Sol-Gel

Synthesis of monophasic ultrafine molybdenum oxide at low temperatures by thermal decomposition of molybdenum acetylacetonate sol-gel is reported. The sol-gel is obtained through a solvent extraction technique from the organic solvent with the reduction in oxidation state of molybdenum. The thermal behaviour of the sol-gel is studied from the thermal analysis traces. The structural changes accompanying the thermal decomposition of the gel and the formation of monophasic molybdenum oxide is also reported with the help of X-ray diffraction and scanning electron microscopy techniques. This revised version was published online in August 2006 with corrections to the Cover Date.     

含镧复合氧化物的合成及其电催化性能

合成了一系列Ｌａ－Ｎｉ－Ｒｕ钙钛矿型复合氧化物，通过ＸＲＤ等测试，讨论了影响复合氧化物合成的因素。采用复合电镀法，将该复合氧化物制成阴极，并进行氢极化曲、连续电极及抗反电流性能测试，证明该复合氧化物具有良好的电催化活性。     

柠檬酸络合-有机模板剂分解法制备介孔La-Co-Ce-O混合氧化物催化剂

 采用柠檬酸络合-有机模板剂分解法制备了不同原子配比的La-Co-Ce-O混合氧化物催化剂. 这些样品具有较大的比表面积(>100 m2/g)和均匀的孔径(3.7～3.9 nm), 并显示出较高的热稳定性. 模板剂分解法制备的样品中CeO2和Co3O4的分散性以及对CO和丙烷氧化的催化活性均明显优于传统共沉淀法制备的样品. 催化剂活性并不与表面钴原子分数成正比,而与表面钴、铈物种间的协同效应密切相关,当表面钴、铈原子分数接近时,协同效应最佳,催化氧化性能最好.     

溶胶负载法制备的Au/AC催化分解低浓度臭氧

采用溶胶负载法制备了高分散的活性炭载纳米Au(Au/AC),研究了其在室温下对低浓度臭氧的催化分解性能,并用N<,2>吸附-脱附、扫描电镜、X射线光电子能谱等手段对反应前后的催化剂进行了表征.结果表明,与普通的传导加热方式相比,微波加热方式所制备的活性炭载Au颗粒的分布更均匀、尺寸更小,具有更高的催化臭氧分解性能.Au前驱体溶液pH值对Au/AC催化剂的臭氧分解性能有显著影响,以pH=8最佳.降低空速而延长臭氧与催化剂的接触时间可以提高催化剂对臭氧的分解性能.空速120000 h-1条件下.催化剂处理约1 g臭氧后,臭氧去除率降低至78.6%:而60 000 h-1条件下处理1.25 g臭氧后,臭氧的去除率仍保持在93.3%.Au/AC催化剂在分解臭氧后,表面部分C被氧化而含氧量增加,但比表面积和孔容等变化不大,主要通过负载Au颗粒本身催化分解臭氧.     

Synthesis of Porous Magnesium Oxide by Thermal Decomposition of Basic Magnesium Carbonate

On calcination of basic magnesium carbonate at 20-800°C, an induction period was observed in the initial stage of thermal decomposition. At the decomposition degree higher than 20% of the weight loss, the specific surface area varied in proportion with the decomposition degree, which points to equal rates of gas liberation and recrystallization of intermediate products into an active oxide. The individual phase of magnesium oxide alone is identified at the minimal temperature of 500°C. As the calcination temperature and time increase, the MgO phase is structured further, which decreases in its specific surface area and basicity.     

烷基羧甲砜基氢氧化铁热脱羧和热分解法制备纳米氧化铁

十六烷基羧甲砜基氢氧化铁和丁基羧甲砜基氢氧化铁通过热脱羧方法,合成了纳米氧化铁颗粒。采用X射线衍射、红外光谱及透射电镜等手段对纳米氧化铁的合成过程和结构特征进行了表征。制备的纳米氧化铁具有8~18 nm的晶粒尺寸。羧甲砜基的热脱羧过程使得表面活性剂从纳米颗粒表面去除相对容易,特别是丁基羧甲砜基化合物。十六烷基羧甲砜基氢氧化铁制备纳米氧化铁颗粒存在脱羧有机分子还原Fe³⁺过程,而丁基羧甲砜基氢氧化铁通过热脱羧分解的方式合成纳米氧化铁颗粒。     

Characterisation and Catalytic Properties of Vanadium Oxide Supported on Alumina Prepared by Sol-Gel Method

Vanadia-alumina xerogels were prepared by sol-gel method using organic precursors of metal and acetic acid as hydrolysis source. The purpose of this work is to study the change in the structure of dispersed vanadia as a function of preparation parameters, mainly the hydrolysis ratio k = [CH₃COOH]/[Al(O-s-Bu)₃] and the vanadium content V/V + Al (%).The amount of acetic acid affects considerably the solid texture, thus the pore size increases with the k ratio. In the same time, ⁵¹V NMR spectroscopy shows a decrease in the vanadium coordination from six-fold to fourfold. The investigation by temperature programmed reduction (TPR) shows that the reducibility of catalysts is determined in the order: K = 3 > K = 2 > K = 1. Furthermore, the catalytic activity in paraxylen oxidation follows a trend similar to that observed in TPR.The increase of vanadium content from 5 to 10%, favours the association of vanadium monomeric species, resulting in a new surface species. Hence, the coordination of vanadium changes from tetrahedral to octahedral, which induces a fall in partial oxidation selectivity.     

Synthesis and Catalytic Property of Fibrous Titanium-Containing Graphite Oxide

A new layered graphite oxide is synthesized by a two-step oxidation of commercial graphite powders, which is further covalently modified by a titanium complex in order for oxidation of alkenes. Characterizations reveal the present graphite oxide is thicker than classical graphene oxide, but shows fibrous morphology after modification of titanium complex. Furthermore, the composition and morphology of synthetic composite are highly relative to the heating condition in preparation. In catalysis, high conversions of alkenes as well as various oxidized products are obtained by using available and green terminal oxidants. Lastly, a composite catalyst is reused for nine rounds in oxidation of R-(+)-limonene, approving its satisfactory stability for recycling. This work provides a highly promising catalytic material, showing values for the design of solid catalysts.     

热氧化制备的钯氧化物电极的组成与pH敏感性能

用钯氧化物电极作pH敏感元件已引起人们的兴趣^[1～3],但对其性能及其与制备条件的关系仍缺乏了解。本文着重讨论热氧化制备的钯氧化物电极的组成和pH敏感性能同氧化温度的关系。     

离子自组装超分子荧光材料及其光致各向异性特性

采用离子自组装的方法,制备了侧链含有肉桂酸光敏基元和二苯乙烯荧光基元的新型超分子复合物PCAMSTIL.通过核磁共振(NMR)和红外光谱(FT-IR)表征了该超分子复合物的结构,并用热重分析(TGA)、紫外可见光谱(UV-Vis)和荧光光谱(FL)研究了其热稳定性和光学性能.将PCAMSTIL旋涂成膜,薄膜经过266 nm偏振脉冲激光辐照后,肉桂酸发生轴向选择的[2+2]加成,薄膜垂直于激光偏振方向的紫外可见吸收明显大于平行方向的吸收,证实薄膜具有取向性.取向薄膜的最大吸收二向色性取向值最大可达0.103,优于一般肉桂酸材料的取向性,肉桂酸分子的取向也引起二苯乙烯荧光分子的协同取向,荧光偏振发射比可达1.73.     

稀土钙钛矿型氧化物催化剂的研究进展

综述了近年来国内外稀土钙钛矿型氧化物催化剂在一氧化碳氧化、甲烷氧化、乙烷氧化、氮氧化物消除和汽车尾气净化等方面的研究进展, 讨论了该类催化材料的结构缺陷与性能之间的构效关系, 简要地分析了今后我国开展稀土钙钛矿型氧化物催化剂研究的重要性及其应用前景.     

Constitution and Properties of Nanocomposites Prepared by Thermal Decomposition of Silver Salts Sorbed by Polyacrylate Matrix

Constitution and dispersity of the products of thermal decomposition of silver nitrate ammonia complex sorbed by polyacrylate matrix are studied by the methods of small- and wide-angle X-ray scattering, optical, photoelectron and Auger-electron spectroscopies. It is shown that, at temperatures of 140–150°C, the complete decomposition of the complex occurs with the formation of nanoparticles and charged silver clusters in polymer bulk. No initial or intermediate products were observed. The average size of obtained nanoparticles is equal to 5 nm. The particles with the size less than 5 nm are amorphous according to X-ray data. The stabilization of nanoparticles occurs due to the adsorption of acrylic copolymer (presumably, via oxygen atoms) on their surfaces. Upon long-term storage in air, the self-diffusion of silver particles and clusters takes place from the surface to composite bulk caused by the detachment of oxygen-containing groups occurring at the metal–polymer interface.     

纳米晶PbTiO3负载CuO催化NO分解

A large specific surface area perovskite-type mixed oxide PbTiO₃ supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H₂-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO₃ was inactive for the reactions, but 1wt % Cu/PbTiO₃ catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO₃. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO₃ support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.