苯氨基甲酸甲酯分解催化剂Bi-Zn复合氧化物的制备及其催化性能

采用共沉淀法制备了一系列Bi-Zn复合氧化物催化剂并将其用于催化苯氨基甲酸甲酯(MPC)分解制备苯基异氰酸酯(PI).用热重、X射线衍射和傅里叶变换红外光谱考察了Bi/Zn摩尔比和焙烧温度对催化剂物相结构和表面性质的影响.结果表明,Zn的加入使Bi_2O_3由α晶相转变为活性更高的β晶相,500℃焙烧时Bi-Zn前驱体分解较为完全,析出Bi_2O_3粒子的同时伴生较多Bi_(7.65)Zn_(0.35)O_(11.83)晶相.在Bi/Zn摩尔比为2/1,焙烧温度为500℃条件下制得的催化剂活性最高,此时MPC转化率为86.O%,PI选择性为91.7%,优于单独使用Bi_2O_3时的催化性能.     

水热法可控制备铋铁系化合物材料

本文以Fe(NO₃)₃·9H₂O和Bi(NO₃)₃·5H₂O为反应原料,以NaOH为矿化剂, 利用水热方法制备出几种纯相的铋铁系化合物材料,通过调节NaOH的浓度范围可以很容易的控制铋铁系化合物的物相。在NaOH浓度为0.1~0.4 mol·L^-1区间,可以得到立方相的软铋矿Bi₂₅FeO₄₀,当NaOH浓度提高到0.8~2.0 mol·L^-1区间,可以得到六方钙钛矿结构的BiFeO₃,再提高NaOH浓度至8.0 mol·L^-1以上可以得到正交相的Bi₂Fe₄O₉,在NaOH浓度为12.0 mol·L^-1时可以获得纳米片状Bi₂Fe₄O₉。同时探讨了铋铁系化合物的生长机理。     

Fabrication of Bismuth/Multi-walled Carbon Nanotube Composite Modified Glassy Carbon Electrode for Determination of Cobalt

A bismuth/multi‐walled carbon nanotube (Bi/MWNT) composite modified electrode for determination of cobalt by differential pulse adsorptive cathodic stripping voltammetry is described. The electrode is fabricated by potentiostatic pre‐plating bismuth film on an MWNT modified glassy carbon (GC) electrode. The Bi/MWNT composite modified electrode exhibits enhanced sensitivity for cobalt detection as compared with the bare GC, MWNT modified and bismuth film electrodes. Numerous key experimental parameters have been examined for optimum analytical performance of the proposed electrode. With an adsorptive accumulation of the Co(II)‐dimethylglyoxime complex at ?0.8 V for 200 s, the reduction peak current is proportional to the concentration of cobalt in the range of 4.0×10^?10?1.0×10^?7 mol/L with a lower detection limit of 8.1×10^?11 mol/L. The proposed method has been applied successfully to cobalt determination in seawater and lake water samples.     

Metal‐Triflate‐Catalyzed Synthesis of Polycyclic Tertiary Alcohols by Cyclization of γ‐Allenic Ketones

It has been established that bismuth(III) triflate catalyzes the cyclization of γ‐allenic ketones under mild reaction conditions. This reaction allows the selective formation of polycyclic tertiary alcohols from cyclic ketone derivatives. The resulting dienols can engage in stereoselective cycloadditions to efficiently afford complex polycyclic systems.     

Strong Stokes and Upconversion Luminescence from Ultrasmall Ln3+‐Doped BiF3 (Ln=Eu3+, Yb3+/Er3+) Nanoparticles Confined in a Polymer Matrix

Heavy metal fluorides like BiF₃ as a host for lanthanide ions are of interest as bismuth is the only heavy metal that is nontoxic. In this work, we report the synthesis of highly water‐dispersible ultrasmall BiF₃ nanoparticles about 6 nm in size within a poly(vinyl pyrrolidone) matrix by a hydrothermal method. Microscopy analysis reveals that the nanoparticles are well separated and confined within the polymer network. These nanoparticles were found to be excellent hosts for lanthanide (Ln³⁺) ions. Through suitable Ln³⁺ doping, BiF₃ exhibits strong emissions in the visible region upon both UV and near infrared (NIR) excitations. The non‐toxicity of both bismuth and PVP can be advantageous for the potential use of BiF₃ nanoparticles in drug delivery and bioimaging.     

Synthesis and Crystal Structure of the Heteropolymate Compound Na_3H_2[Ce_3(H_2O)_(18)Bi_2W_(22)O_(76)]·23H_2O

1 INTRODUCTION As a rich remarkable class of inorganic cluster systems, polyoxometalates continue to be the focus of significant attention in the 21th century because of their various and alluring topologies as well as their unusual physicochemical prope…     

Crystallographic report: Bis[tris(morpholindithiocarbamato)bismuth(III)]

The dimeric and centrosymmetric structure of {Bi[S₂CN(CH₂CH₂)₂O]₃}₂ features chelating dithiocarbamate ligands and intermolecular Bi? S interactions, so that a distorted pentagonal bipyramidal S₇ coordination geometry results. Copyright © 2004 John Wiley & Sons, Ltd.