表面修饰DBS基团对TiO2气相光催化性能的影响

采用溶胶-水热法直接获得表面修饰十二烷基苯磺酸钠(DBS)分子基团的TiO2纳米粒子, 并考察了DBS表面修饰对纳米TiO2光催化氧化降解气相n-C5H12反应的活性和寿命的影响, 并利用表面光电压(SPS)谱和光致发光(PL)光谱等方法研究了DBS表面修饰的影响机制. 结果表明, 表面修饰DBS分子基团能够抑制TiO2纳米微晶生长, 促进纳米TiO2分散, 增强吸附性和提高光生电荷分离, 使光催化活性显著提高. 但寿命并未下降, 这与TiO2和DBS基团的光稳定性有关. 动力学研究结果表明, TiO2光催化氧化n-C5H12反应遵循Langmuir-Hinshelwood动力学模型, 为准一级反应.     

Advanced analytical techniques: platform for nano materials science

This paper reviews a range of instrumental microanalytical techniques for their potential in following the development of nanotechnology. Needs for development in secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), Auger emission spectrometry (AES) laser mass spectrometry, X-ray photon spectroscopy are discussed as well as synchrotron-based methods for analysis. Objectives for development in all these areas for the coming 5 years are defined. Developments of instrumentation in three European synchrotron installations are given as examples of ongoing development in this field.     

新型固载化螯合钛酸酯催化合成高沸点酯的研究

新型固载化螯合钛酸酯催化合成高沸点酯的研究１）刘继红王春凤车丕智邢伯军孔祥球（哈尔滨师范大学化学系哈尔滨１５００８０）关键词固载化螯合钛酸酯催化剂高沸点酯酯化反应分类号Ｏ６４３．３２目前，固载化催化剂以其独特的功能日益受到人们的重视．均相催化剂的高分...     

二维层状配位聚合物{[Cd(p-CMSP)(Him)(H2O)]·3H2O}n

The novel coordination polymer {[Cd(p-CMSP)(Him)(H₂O)]·3H₂O}_n ( p-CMSP^2-=p-(carboxymethoxy)phenylthioacetate, Him=imidazole) was synthesized by the reaction of Cd(NO3)₂, imidazole and p-(carboxymethoxy)phenylthioacetic acid in an aqueous solution, and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The crystal structure is of monoclinic, space group P2₁/c with a=1.144 0(2) nm, b=1.876 7(4) nm, c=0.877 89(18) nm, β=106.31(3)° and V=1.808 9(7) nm³, Z=4, R=0.023 2, wR=0.051 4. Each Cd(II) atom displays a distorted octahedral coordination geometry, defined by three carboxyl O atoms from different p-CMSP^2- ligands, one S atom from thioether, one N atom from imidazole and one water molecule. Adjacent Cd(II) ions are bridged by p-CMSP^2- groups, resulting in a 2D layer structure. The adjacent Cd…Cd distances are 0.492 7 nm and 1.144 0 nm. Furthermore, such layers are linked through hydrogen bonds to form supramolecular network. CCDC: 269474.     

Complete reversal of enantioselection using oxazoline-containing Schiff base ligands derived from l-serine in enantioselective addition of diketene to aldehydes

Starting from one stereogenic center (in this case from l-serine), we obtained two chiral Schiff bases possessing oxazoline moieties, each of which recognized a different enantioface of aldehydes with a high enantiomeric excess [up to 93% ee (R) and 89% ee (S)] in the addition reaction of diketene to 2-furfural.     

合成介质对稀土铽-邻苯二甲酸有机配合物荧光强度的影响

在不同介质(依次为甲醇、乙醇、正丙醇、正丁醇)中合成了邻苯二甲酸Tb3+稀土二元配合物. 利用元素分析和红外光谱分析等对配合物的组成和结构进行了表征. 荧光光谱结果表明, 直链醇作为合成介质时配合物的荧光强度大小顺序依次为: 甲醇>乙醇>正丙醇>正丁醇. 同时该配合物在2~300 K范围内测定的变温磁化率说明该配合物具有反铁磁性.     

Resonance-enhanced 2-photon ionization studies of induction period of methane dehydro-aromatization over Mo/HZSM-5

The behavior of benzene produced during the fixed-temperature reaction and the temperature-programmed surface reaction of methane under non-oxidation aromatization over Mo/HZSM-5 catalyst was monitored in real-time by the resonance-enhanced 2-photon ionization technique. A new phenomenon of benzene formation in the induction period is found to correspond to the migration of the molybdenum species in the catalyst. This revised version was published online in June 2006 with corrections to the Cover Date.     

Selective skeletal isomerization of n-butene over modified MCM-22 zeolite catalysts

Summary Modification of HMCM-22 zeolite with tetraethoxysilane (TEOS) can considerably improve the catalytic performances, especially the selectivity to isobutene, for the reaction of n-butene skeletal isomerization.     

Ab initio studies of structural and electronic properties of Li4Ti5O12 spinel

Structural and electronic properties of Li₄Ti₅O₁₂ spinel are studied from density functional theory based first principles calculations. Differences on these properties between delithiated state Li₄Ti₅O₁₂ and lithiated state Li₇Ti₅O₁₂ are compared. The optimized lattice constant of Li₄Ti₅O₁₂ is 8.619 Å, which is even a little larger (0.2%) than 8.604 Å of the lithiated state Li₇Ti₅O₁₂. The arrangement of the Li and Ti atoms at the 16d sites of the spinel structure is also investigated in a cubic unit cell. Large 1 × 1 × 3 supercell models are constructed and used to calculate the total energy and electronic structure. The average intercalation potential is also calculated, with metallic lithium as reference.