Cu/NiO-MoO3/SiO2光催化CO2与CH3OH合成碳酸二甲酯的反应性能

 采用表面改性法制备了MoO3-SiO2复合氧化物,用等体积浸渍法制备了Cu/NiO-MoO3/SiO2光催化剂,并用XRD, Raman, IR, TPD-MS, UV-Vis DRS和光促表面反应研究了催化剂的结构、化学吸附性能、吸光性能和光促CO2与CH3OH合成碳酸二甲酯(DMC)的反应性能. 结果表明, Cu和NiO的引入提高了MoO3在SiO2表面的分散度,且Cu和NiO在MoO3-SiO2表面分散均匀; 在金属Cu位和Lewis酸位Mo6+(或Ni2+)的协同作用下, CO2在催化剂表面形成活性较高的的卧式吸附态, CH3OH在催化剂表面形成分子吸附态和解离吸附态; NiO与MoO3复合后部分形成了 Mo-O-Ni 键联,提高了对光的吸收强度; 金属Cu的负载扩展了材料在可见光范围的吸收; 与热表面催化相比,光催化反应在较低的温度下就能显著进行,并提高了CH3OH的转化率,在110 ℃常压和空速300 h-1的条件下,CH3OH转化率可达13.9%,DMC选择性可达90.1%.

Photocatalytic Reaction for Synthesis of Dimethyl Carbonate from CO2 and CH3OH over Cu/NiO-MoO3/SiO2 Catalyst

The Cu/NiO-MoO_3/SiO_2 catalyst was made by the methods of surface reaction modification and isometric impregnation.The structure,chemisorption and photoabsorption properties of Cu/NiO-MoO_3/SiO_2 were studied by XRD,Raman,IR,TPD and UV-Vis DRS techniques,and the reaction behavior for the photocatalytic reaction of CO_2 and CH_3OH to dimethyl carbonate(DMC) was studied by photo-stimulated reaction technique.The results showed that the addition of Cu and NiO greatly increased the dispersion of MoO_3 on SiO_2,and Cu and NiO could also disperse evenly on the support.The CO_2 horizontal state with high activity and the CH_3OH molecular and dissociative adsorption states formed on the surface of Cu/NiO-MoO_3/SiO_2 catalyst under the synergic action of metallic Cu sites and Lewis acid sites(Mo~(6+) or Ni~(2+)).The(Mo-O-Ni) bonds formed and the absorption intensity was enhanced through the coupling of MoO_3 and NiO.The absorption region was expanded to visible light after Cu was supported on the coupled semiconductor NiO-MoO_3/SiO_2.Compared with the thermal surface catalytic reaction,the photo-stimulated surface reaction for synthesis of DMC from CO_2 and CH_3OH over Cu/NiO-MoO_3/SiO_2 could proceed at lower reaction temperature and give higher reactant conversion.Under the proper conditions,the CH_3OH conversion was up to 13.9% with DMC selectivity of 90.1%.