摘要
A series of Co/TiO2 catalysts were prepared by incipient wetness impregnation. The pH value of the impregnation solution was adjusted by using nitric acid and urea. The XRD, TPR and XPS characterization results indicate that the change of the pH value of the impregnation solution is correlated with the crystal particle size of cobalt oxide species (Co3O), dispersion behavior and metal-support interaction. When the pH value of the solution is higher than the IEP (ion equipotential point) of titania, the larger Co3O4 particle size could be obtained on the surface of the catalyst. High pH value favores the adsorption and dispersion of active cobalt species over the titanium dioxide, and facilitates the interaction between cobalt and titania, and depresses the reduction degree of the catalyst. In the F-T reaction, catalysts prepared at high pH value have low activities and high methane selectivities. When the pH value of the solution is lower than the IEP of titania, the Co3O4 particle size is small, the interactions between cobalt species and support are weak and the reduction degrees are high, which further enhance the F-T reaction activity and suppress methane selectivity.
A series of Co/TiO2 catalysts were prepared by incipient wetness impregnation. The pH value of the impregnation solution was adjusted by using nitric acid and urea. The XRD, TPR and XPS characterization results indicate that the change of the pH value of the impregnation solution is correlated with the crystal particle size of cobalt oxide species (Co3O4) , dispersion behavior and metal-support interaction. When the pH value of the solution is higher than the IEP (ion equipotential point) of titania, the larger Co3O4 particle size could be obtained on the surface of the catalyst. High pH value favores the adsorption and dispersion of active cobalt species over the titanium dioxide, and facilitates the interaction between cobalt and titania, and depresses the reduction degree of the catalyst. In the F-T reaction, catalysts prepared at high pH value have low activities and high methane selectivities. When the pH value of the solution is lower than the IEP of titania, the Co3O4 particle size is small, the interactions between cobalt species and support are weak and the reduction degrees are high, which further enhance the F-T reaction activity and suppress methane selectivity.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2005年第4期506-508,共3页
Journal of Fuel Chemistry and Technology
基金
国家重点基础研究发展规划(973计划
G1999022402)~~