MoO_3-TiO_2/SiO_2上光促表面催化甲烷和水合成甲醇和氢气

Photo Stimulated Surface Catalytic Syntheses of Methanol and Hydrogen from Methane and Water over MoO_3-TiO_2/SiO_2

用分步等体积浸渍法制备了负载型复合半导体催化剂 Mo O3-Ti O2 / Si O2 ,通过 XRD,BET,TPR,IR,UVDRS和 TPD等手段对其进行了表征 ,结果表明 ,活性组分在载体表面高度分散 ,并具有量子尺寸效应 ,吸光阈值显著蓝移 ;Ti O2 在 Si O2 表面分散可增强 Mo O3与载体的相互作用 ,调变吸光性能 ,所形成的表面活性基元能够有效地吸附活化甲烷和水 .在 1 0 0℃下利用固定床环隙反应器借助紫外光的激发 ,通过“光 -表面 -热”协同作用 ,气相甲烷和水在 Mo O3-Ti O2 / Si O2 表面生成了甲醇和氢 ,选择性达到 85 .6% .

TiO_2/SiO_2 were prepared by the chemical modification reaction on SiO_2,and MoO_3-TiO_2/SiO_2 were prepared by isovolumetric impregnation of TiO_2/SiO_2. Based on the characterization of XRD,BET,TPR,UVDRS,IR and TPD,the surface species of supported n-p coupled semiconductors(MoO_3-TiO_2/SiO_2) are well-dispersed,which have the quantum size effects and make the photo absorption threshold blue-shifting. The experiments also confirmed that the incorporation of TiO_2 can not only enhance the interaction between MoO_3 and supports but also improve photo absorption property. In addition,the reactants CH_4 and H_2O can be adsorbed and activated effectively. The gas-phase photocatalytic production of CH_3OH and H_2 from CH_4 and H_2O was performed in the presence of MoO_3-TiO_2/SiO_2 at 100 ℃ by using a fixed-bed annular photoreactor under UV irradiation,with a selectivity of CH_3OH being 85.6%. The “photo-surface-thermal” synergistic action can be formed at the reaction temperature,which accelerated the photocatalytic reaction. And the reaction mechanism was proposed. [WT5HZ]