Heterogeneous Acid Catalytic Esterification by Porous Polyoxometalate-tantalum Pentoxide Nanocomposites  

作　　者：许蕾蕾 GUOYihang MA Huiru 官建国 

机构地区：[1]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology [2]School of Chemistry, Northeast Normal University

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2013年第3期580-585,共6页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Natural Science Foundation of China(No.51002111);the Fundamental Research Funds for the Central Universities(No.2012-IV-085)

摘　　要：Polyoxometalates （POMs） are useful catalysts in both redox and acid catalysis reactions since its catalytic features can be controlled at a molecular level. We investigated POM （POM = H3PW12040） on tantalum pentoxide （Ta2O5） via hydrolysis of tantalum pentachloride （TaCl5） in the presence of POM using the sol-gel method for acid catalytic reaction. All obtained amorphous materials have been characterized by inductively coupled plasma atomic emission spectroscopy （ICP-AES）, Fourier transform infrared （FT-IR） spectra, Raman scattering spectroscopy, 31P magic-angle spinning （MAS） NMR, field emission scanning electron microscopy （FESEM）, and nitrogen adsorption/desorption analysis, in order to confirm the structure integrity of the Keggin unit in as-prepared composites and investigate the morphology and surface textural property of the composites. Catalytic activity of the catalysts has been evaluated for esterification of acetic acid with ethanol as a model reaction with different catalytic reaction parameters such as POM loading, reaction time, catalyst dose, molar ratio of the reactants, etc. The conversion of ethanol reached 87.4 % and the turnover frequency （TOF） was 2.9x 103.Meanwhile, it is easy to separate and recover POM/Ta205 from the reaction system.Polyoxometalates （POMs） are useful catalysts in both redox and acid catalysis reactions since its catalytic features can be controlled at a molecular level. We investigated POM （POM = H3PW12040） on tantalum pentoxide （Ta2O5） via hydrolysis of tantalum pentachloride （TaCl5） in the presence of POM using the sol-gel method for acid catalytic reaction. All obtained amorphous materials have been characterized by inductively coupled plasma atomic emission spectroscopy （ICP-AES）, Fourier transform infrared （FT-IR） spectra, Raman scattering spectroscopy, 31P magic-angle spinning （MAS） NMR, field emission scanning electron microscopy （FESEM）, and nitrogen adsorption/desorption analysis, in order to confirm the structure integrity of the Keggin unit in as-prepared composites and investigate the morphology and surface textural property of the composites. Catalytic activity of the catalysts has been evaluated for esterification of acetic acid with ethanol as a model reaction with different catalytic reaction parameters such as POM loading, reaction time, catalyst dose, molar ratio of the reactants, etc. The conversion of ethanol reached 87.4 % and the turnover frequency （TOF） was 2.9x 103.Meanwhile, it is easy to separate and recover POM/Ta205 from the reaction system.

关 键 词：ESTERIFICATION POLYOXOMETALATE tantalum pentoxide SOL-GEL porous mataterials 

分 类 号：TB33[一般工业技术—材料科学与工程]