Pd/MoO3-TiO2/SiO2光催化CO2与C2H6合成烃类氧化物的反应性能

 采用化学反应改性和等体积浸渍法制备了负载型Pd/MoO3-TiO2/SiO2催化剂,并用IR,FT-Raman,TPD-MS,UV-Vis DRS和活性评价等方法研究了催化剂的表面结构、光吸收性能、化学吸附性能及光催化CO2与C2H6合成烃类氧化物的反应性能. 结果表明,SiO2负载的MoO3和TiO2之间存在着强相互作用,并能部分形成Mo-O-Ti键联,使得两种氧化物微粒均匀分布于载体表面; 表面MoO3和TiO2的复合作用使TiO2/SiO2的吸光带边红移,扩展了其吸光域,Pd的引入明显提高了固体材料的可见光吸收率; CO2和C2H6能较好地吸附在催化剂表面,在紫外光的激发下,CO2吸附态能解离生成CO,而C2H6单位吸附态能部分转化为C和H同时吸附在两个晶格氧上的双位吸附态; 光促CO2和C2H6反应主要生成丙醛、乙醇和乙醛; 在合适的条件下,烃类氧化物的选择性可超过90%.

Photocatalytic Synthesis of Hydrocarbon Oxygenates from CO2 and C2H6 over Pd/MoO3-TiO2/SiO2 Catalyst

The supported Pd/MoO3-TiO2/SiOe semiconductor material catalyst was prepared by surface modification and incipient wetness impregnation. The surface structure, photoabsorption performance, chemisorption properties and photocatalytic activity of the catalyst samples were characterized by IR, FT-Raman, UV-Vis DRS, TPD-MS and photocatalytic reaction of CO2 and C2H6 to hydrocarbon oxygenates, respectively. The results showed that all active components were dispersed homogeneously on the support surface as a result of strong interaction between MoO3 and TiO2. A significant red shift of the absorption edge was brought out owing to the formation of Mo-O-Ti bond, and the extension for photoabsorption range of the catalyst occurred. The addition of metal Pd improved photoabsorptivity of the semiconductor materials obviously. CO2 and C2H6 could be chemisorbed on the support surface, CO2 could be dissociated to CO, and a new adsorption state of C2H6 could be formed under UV irradiation. Photocatalysis reaction of CO2 and C2H6 produced mainly propanal, ethanol and acetaldehyde. Under the proper conditions, the selectivity for hydrocarbon oxygenates was more than 90 %.