纤维素-三(3,5-二甲基苯基氨基甲酸酯)涂敷氧化锆手性固定相的制备和色谱评价

制备并表征了涂敷纤维素-三(3，5-二甲基苯基氨基甲酸醋)-ZrO2手性固定相。以正己烷／异丙醇为流动相，研究了正相色谱条件下手性固定相对几类光学异构体的手性拆分能力。实验结果表明：氧化锆载体表面的碱性性质对光学对映体的手性拆分有很大影响；在常用流动相条件下，酸性对映体被完全滞留；纤维素-三(3，5-二甲基苯基氨基甲酸醋)-ZrO2手性固定相对于中性及碱性对映异构体的分离呈现出较好的手性拆分能力。     

Influence of the Plasma Chemistry on the Composition of ZrOx and NbOx Thin Films Deposited by Reactive Magnetron Sputtering

The plasma chemistry of magnetron sputtered Zr and Nb in an Ar/O₂ atmosphere has been measured as a function of the O₂ partial pressure. The previously reported composition of films deposited onto grounded non-intentionally heated substrates was correlated with the dominant positive and negative ion populations in the plasma. While the oxygen deficient films were grown in the Ar⁺ dominant mode, the close-to-stoichiometric films were grown in the O⁺/O⁻ dominant mode. The formation of close-to-stoichiometric ZrO_2.1 is observed in the compound mode (CM), while the formation of close-to-stoichiometric Nb₂O_4.7 thin films was reported in addition to the CM also in the transition mode (TM). This may be understood based on the 1.5–1.9 times higher power dissipated in the Nb–Ar–O₂ plasma as compared to the Zr–Ar–O₂ plasma. We suggest that at larger power O₂ dissociation may be more efficient and lead to the presence of sufficient atomic oxygen to fully oxidize the films. This finding may provide a pathway towards a deposition rate enhancement, since compound formation at the substrate is enabled in the TM of the higher power Nb–Ar–O₂ plasma and not only in the CM, as in the case of the lower power Zr–Ar–O₂ plasma.     

PICA法制备用于高效液相色谱的锆胶基质柱填料

迄今 ,硅胶基质固定相在 HPLC领域仍占据主导地位 ,但由于它的 p H使用范围窄 ,尤其在碱性条件下基质逐渐溶解 ,其使用受到限制 [1] .为此 ,寻找稳定性能高的新基质成为当前色谱学研究的热点之一 ,二氧化锆因具有良好化学稳定性和机械强度而受到关注 .目前 ,制备微米级、球形和多孔二氧化锆基质柱填料的常用方法有两种 :(1 )油乳化法 (OEM) ;(2 )聚合诱导胶体凝聚法 (PICA) .OEM法操作简单 ,但制备的二氧化锆微球粒径分布宽且孔径较小 .Carr[2 ,3] ,Unger[4 ] ,Rassi[5,6 ]和 Kawahara等[7,8] 在用 OEM法制备二氧化锆微球方面做了…     

环己酮肟在改性氧化锆催化剂上的Beckmann重排反应Ⅲ．B_2O_3对ZrO_2的改性效应

采用ＩＲ和ＸＲＤ技术研究了Ｂ２Ｏ３／ＺｒＯ２催化剂的结构性质，用ＩＣＰ－ＭＳ测定了样品中Ｂ２Ｏ３的含量，通过Ｈａｍｍｅｔ指示剂正丁胺滴定法测定了Ｂ２Ｏ３／ＺｒＯ２系列催化剂的表面酸性；研究了载体预处理温度对样品表面酸性和结构的影响，以及Ｂ２Ｏ３含量对样品催化性能的影响；比较了Ｂ２Ｏ３负载于ＺｒＯ２，Ａｌ２Ｏ３，ＳｉＯ２，ＴｉＯ２，ＭｇＯ和ＨＺＳＭ－５上催化活性和目的产物选择性的差异，讨论了Ｂ２Ｏ３／ＺｒＯ２催化剂在气固相Ｂｅｃｋｍａｎｎ重排反应中的作用特点     

聚合物包覆二氧化锆液相色谱固定相的制备与评价

在溶液体系中通过自由基引发长链碳烯-1、二乙烯苯和乙烯基二氧化锆交联聚合反应得到聚长链碳烯-苯乙烯包覆二氧化锆固定相.考察了这种交联聚合物包覆柱填料的色谱性能和化学稳定性,并用这种填料分离了稠环芳烃和碱性化合物.     

Au/ZrO2催化剂中ZrO2的尺寸效应:1,3-丁二烯加氢反应

在不同温度(673～1073K)下,于流动N2气中焙烧ZrO(OH)2醇(乙醇)凝胶,制备了不同尺寸的ZrO2-AN纳米晶(6～30nm).采用沉积-沉淀方法制备了相应的质量分数为0.7%的Au/ZrO2-AN催化剂.用XRD,XRF,TEM/HRTEM,EDS,N2吸附和1,3-丁二烯加氢反应对ZrO2-AN和Au/ZrO2-AN催化剂进行了表征.结果表明,在所有的Au/ZrO2-AN样品中,Au粒子的平均尺寸为4～5nm,ZrO2-AN的颗粒大小没有因为负载Au粒子而发生改变.1,3-丁二烯在Au/ZrO2-AN催化剂催化下能以100%的选择性进行加氢反应生成单烯烃.随着Au/ZrO2-AN催化剂中ZrO2-AN纳米晶尺寸的增加或“载体”焙烧温度的升高,1,3-丁二烯的转化率明显降低;1-丁烯的选择性先增加后减小,2-丁烯中反/顺异构体的摩尔比在0.5～1.0的范围内逐渐增大,TEM/HRTEM表征结果清楚地表明,Au/ZrO2-AN催化剂中Au粒子与ZrO2-AN颗粒接触界面/周边随ZrO2-AN颗粒尺寸的减小而明显增加,这很可能是含有更小尺寸ZrO2-AN纳米粒子的Au/ZrO2-AN催化剂具有更高的催化活性的重要原因.     

In situ fabrication of polyacrylate/nanozirconia hybrid material via frontal photopolymerization

Frontal photopolymerization was applied to fabricate polymer/nanozirconia hybrid material by using acrylates as polymerizable components and tetrabutyl zirconate (TBZ) as the precursor of nanozirconia, respectively. The nanozirconia particles were in-situ generated with the polymerization front traveling and gradiently dispersed in the simultaneously formed polymer rod. The iodonium salt was utilized as photoacid generator to produce protonic acid and drive TBZ into nanozirconia particles. With the frontal polymerization traveling downward, the particle size and concentration of zirconia increased, but layer-resolved conversion of TBZ decreased. The particle size of zirconia could be reduced remarkably by the protection of monoalkyl titanate bearing six long chains. The refractive index of the hybrid rod was found to increase from top to down. The top–down layer-resolved storage modulus of the hybrid rod increased due to nanoparticle filling effect but decreased beyond the depth of 4 cm from the top, which may be ascribed to particle aggregation. This project is supported by the National Natural Science Foundation of China (grant no. 20304019, 60378029).     

Study of thermal transfer in oxygen lambda sensors

Chemical sensors based on zirconia solid electrolyte are widely used in cars for control of air/fuel ratio. Their application is based on the sharp change of electromotive force (emf) at the stoichiometric point (lambda λ = 1). On the basis of experimental measurements of electrical input into the sensor heater and emf’s at selected temperatures under controlled conditions, a heat transfer model has been constructed to characterize the behavior of oxygen lambda sensors.     

Separation of enantiomers on bovine serum albumin coated zirconia in reversed-phase liquid chromatography

Summary Zirconia is known to be one of the best materials for the chromatographic support due to its excellent chemical, thermal and mechanical stability. In this work we report preparation and use of bovine serum albumin (BSA)-immobilized zirconia as a chiral stationary phase for separation of some enantiomers in reversed-phase liquid chromatography. The BSA-zirconia showed good enantioselectivity for some of the enantiomers studied and could be used for RPLC separations in mobile phases of alkaline pH.     

Studies on the ZrO/W(100) surface by means of low-energy electron diffraction and X-ray photoelectron spectroscopy

The low work-function ZrO/W(100) surface was examined with the aim of understanding the reducing mechanism of the work function. Low-energy electron diffraction (LEED) was employed to analyze the surface atomic arrangement, and X-ray photoelectron spectroscopy (XPS) was used to identify the surface chemical condition. The ZrO/W(100) surface was made as follows: (i) around three monolayers of Zr were deposited on a clean W(100) surface, (ii) the sample was heat treated in an oxygen ambience of 1.3x10⁻⁵ Pa for several tens of minutes at 1500 K, and (iii) the sample was flash heated at 2000 K in ultrahigh vacuum (UHV). During heat treatment in O₂, the deposited Zr was oxidized to ZrO₂, and the LEED pattern formed was p(2×1). The work function increased to 5.3 eV. Subsequent flash heating in UHV changed the p(2×1) LEED pattern into a c(4×2) pattern, and transformed ZrO₂ into the so-called Zr–O complex, the oxidized level of which is between ZrO₂ and metallic Zr. A drastic decrease in the work function to 2.7 eV ensued. The angular dependence of XPS showed that the Zr–O complex segregated within a few monolayers at the surface.