过渡金属Ni催化的共轭二烯烃的双硼化反应机理研究

运用密度泛函理论(DFT)对过渡金属Ni(0)催化1,3-丁二烯的双硼化反应机理进行了研究。通过在B3LYP水平下对反应路径的中间体和过渡态进行优化计算,确定了可能的反应路线。对反应路线中所涉及的Ni配位化合物进行了深入研究,并对反应中相应的过渡态和中间体进行了自然键轨道(NBO)分析。结果表明,Ni(0)催化1,3-丁二烯的双硼化反应是一个1,4-加成过程;反应主要经历氧化硼迁移和还原消除两个步骤,其中,氧化硼迁移为该反应的决速步骤,能垒为73.0kJ·mol-1。     

Catalytic combustion study of soot on Ce0.7Zr0.3O2 solid solution

The Ce0.7Zr0.3O2 solid solution and CeO2 were prepared using the sol-gel method. The phase structure, crystallite sizes and the reducibility of the catalysts were characterized by XRD and H2-TPR techniques. XRD results indicated that Zr^4＋ had replaced part of Ce^4＋ to form a fluorite-like solid solution, which was favorable to obtain ultrafine nanoparticles. The ratio of main HE consumption for Ce0.7Zr0.3O2：CeO2 was 4.4：1.0, implying that the solid solution could improve the reducibility compared to the single CeO2. The Ce0.7Zr0.3O2 solid solution catalyst showed a sharp combustion peak at 397 ℃, which was 200 ℃ lower than that of the single soot. The good catalytic activity of the Ce0.7Zr0.3O2 was attributed to the formation of nano-CeO2-based solid solution, which enhanced the reducibility and then improved the combustion activity. As Ce0.7Zr0.3O2 could be easily reduced to Ce0.7Zr0.3O2-x meanwhile, after oxygenation, the Ce0.7Zr0.3O2.x was recovered to Ce0.7Zr0.3O2 completely. A catalytic combustion reaction mechanism was proposed： the Ce0.7Zr0.3O2 was reduced to Ce0.7Zr0.3O2-x by the reaction with carbon and then it was recovered to Ce0.7Zr0.3O2-x by the interaction with O2.     

碳纳米管修饰石墨电极的制备及应用

研究了多壁碳纳米管修饰石墨电极(MWNT/CE)的方法,并比较了不同修饰方法(嵌入法和涂层法)的修饰效果和修饰电极的稳定性.利用该修饰电极对马来酸噻吗洛尔(MET)的电催化作用,建立了一种新的电化学定量分析MLT的方法.在0.2 mol/L KNO3+0.1mol/L CH3COOH-CH3COONa(pH=4.82)体系中,MLT的浓度在2.3×10-5mol/L～5.8×10-4mol/L范围内时,氧化峰电流与浓度呈现良好的线性关系,线性相关系数为0.9996,检测限达5.6×10-6mol/L.该修饰电极用于含MLT药物样品的分析,八次平行测定结果的相对标准偏差为1.2%,样品回收率为95.1%～101.8%,结果令人满意.