纳米氧化锰负载钛基电催化膜制备及其苯甲醇催化氧化性能

利用乳液法制备出MnO_x纳米颗粒,将其负载于微孔管式钛膜制得MnO_x负载钛基电催化膜(MnO_x/Ti).运用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、循环伏安法(CV)和计时电流法(CA)等表征方法系统考察了不同焙烧温度下MnO_x晶型结构、MnO_x/Ti催化膜电化学性能以及催化氧化苯甲醇的变化规律.结果表明:随着焙烧温度的升高, MnO_x的晶型由初始的Birnessite-MnO₂逐渐转变为K_0.27MnO₂,再由Mn3O4最终转变为α-MnO₂.所得MnO_x/Ti膜中, α-MnO₂晶粒尺寸小于30 nm,结晶度较高,颗粒分布均匀.同时,由于其含有不饱和配位的锰原子和氧空位以及与基体Ti之间存在键合作用,表现出优异的电化学性能和催化性能.以450 ℃焙烧所得的α-MnO₂/Ti为阳极构建电催化膜反应器催化氧化苯甲醇.在反应温度为25 ℃, 50mmol·L^-1苯甲醇水溶液,电流密度为2 mA·cm^-2,停留时间为15 min的条件下,膜反应器苯甲醇转化率达64%,苯甲醛选择性为79%.

Preparation of Nano-Manganite Loaded Titanium Electocatalytic Membrane for the Catalytic Oxidation of Benzyl Alcohol

MnO_x nanoparticles obtained by the emulsion method were loaded on a microporous tubular titanium membrane to prepare a functional MnO_x/Ti electrocatalytic membrane. The effects of calcination temperature on the crystal structure of MnO_x as well as the electrochemical properties and catalytic performance to oxidize benzyl alcohol of MnO_x/Ti membrane were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), cyclic voltammetry (CV), chronoamperometry (CA), and other characterization methods. The results indicated that the crystal structure of MnO_x was gradually transformed from Birnessite-MnO₂ to K_0.27MnO₂, and finally to α-MnO₂ from Mn3O4 with increasing calcination temperature. The α-MnO₂ particles in the MnO_x/Ti electrocatalytic membrane showed high crystallinity and uniform particle size (less than 30 nm). The superior electrochemical properties and catalytic performance of α-MnO₂/Ti membrane obtained at a calcination temperature of 450 ℃ could be attributed to the binding effects between unsaturated coordination atoms of Mn and oxygen vacancies with the Ti substrate. The α-MnO₂/Ti membrane obtained at 450 ℃ was used as the anode to assemble an electrocatalytic membrane reactor to oxidize benzyl alcohol. 64% conversion of benzyl alcohol and 79% selectivity to benzaldehyde was achieved under the operating conditions: reaction temperature 25 ℃, aqueous benzyl alcohol solution of 50 mmol·L^-1, current density 2 mA·cm^-2, and residence time 15 min.