Pd catalysts supported on rGO-TiO_2 composites for direct synthesis of H_2O_2: Modification of Pd^(2+)/Pd^0 ratio and hydrophilic property  

作　　者：Shuying Chen Rui Tu Jun Li Xiaohua Lu 

机构地区：[1]State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University

出　　处：《Chinese Journal of Chemical Engineering》2018年第3期534-539,共6页中国化学工程学报（英文版）

基　　金：Supported by the National Key Basic Research Program of China(2013CB733505,2013CB733501);the National Natural Science Foundation of China(91334202);the Natural Science Foundation of Jiangsu Province of China(BK2012421,BK20130062);the Research Fund for the Doctoral Program of Higher Education of China(20123221120015);the Project for Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)

摘　　要：The use of nanostructured composites as catalyst supports is a promising route to prepare catalysts with high selectivity and productivity. In this work, reduced graphene oxide-TiO_2(rGP-x) composites with a variation of reduced graphene oxide(rGO) content were synthesized by hydrothermal method. Pd/rGP-x catalysts were prepared in incipient-wetness impregnation method for the direct synthesis of H_2O_2 from H2 and O_2. The morphology and electronic properties of catalysts were investigated by XPS, TEM, and Raman spectroscopy.The ratio of Pd^(2+)/Pd^0 and the hydrophobicity of the catalysts were increased with the rising content of rGO. As the amount of rGO in the catalysts varied in the range of 0.025 wt%–2 wt%, the selectivity of H_2O_2 exhibited a tendency of increasing firstly and then decreasing from 0.1 wt% to 2 wt%. It indicates that good catalytic performance for H_2O_2 synthesis can be achieved only when appropriate amount of rGO is introduced. The H_2O_2 selectivity and productivity of Pd/r GP-0.025 both improved remarkably compared with Pd/P25. This enhancement originated from the combined effects of the proper ratio of Pd^(2+)/Pd^0 and hydrophobicity of the catalyst.The use of nanostructured composites as catalyst supports is a promising route to prepare catalysts with high selectivity and productivity. In this work, reduced graphene oxide-TiO2 （rGP-x） composites with a variation of reduced graphene oxide （rGO） content were synthesized by hydrothermal method. Pd/rGP-x catalysts were prepared in incipient-wetness impregnation method for the direct synthesis of H2O2 from H2 and O2. The morphology and electronic properties of catalysts were investigated by XPS, TEM, and Raman spectroscopy. The ratio of Pd^2＋/Pd^0 and the hydrophobicity of the catalysts were increased with the rising content of rGO. As the amount of rGO in the catalysts varied in the range of 0.025 wt%-2 wt%, the selectivity of H2O2 exhibited a tendency of increasing firstly and then decreasing from 0.1 wt% to 2 wt%. It indicates that good catalytic performance for H2O2 synthesis can be achieved only when appropriate amount of rGO is introduced. The H2O2 selectivity and productivity of Pd/rGP-0.025 both improved remarkably compared with Pd/P25. This enhancement originated from the combined effects of the proper ratio of Pd^2＋/Pd^0 and hydrophobicity of the catalyst.

关 键 词：Direct H2O2 synthesis Reduced graphene oxide Hydrothermal Electronic structure Desorption Selectivity 

分 类 号：O643.36[理学—物理化学] TS745[理学—化学]