用EXAFS方法研究双功能催化剂NiO-MoO3/γ-A2O3的表面分散那

Surface Dispersion Studies of Bifunctional NiO-MoO3/γ-Alumina Catalyst by EXAFS

The surface dispersion of bifunctional NiO-MoO_3/γ-alumina catalysts prepared by different procedures was studied with Ni-K EXAFS spectroscopy. The contents of NiO(13.6%) and MoO_3(16.5%) were the same in the three samples, which were a little higher than the monolayer dispersion capacity of each component on γ-Al_2O_3. The dispersion temperature was 450 ℃. The sample impregnated with NiO first shows that the NiO is monolayer-dispersed on γ-Al_2O_3 surface and the outer layer is MoO_3. The sample impregnated with MoO_3 and the outer layer is NiO. There is strong interaction between MoO_3 and γ-Al_2O_3 which affects the dispersion of NiO on the surface. The sample impregnated with NiO and MoO_3 simultaneously shows that the Ni is not dispersed in the form of NiO but another compound on the surface.