The universality of like-disperses-like rule for supported simple metal oxide catalysts

The rutile SnO₂ monolayer dispersion capacity on the rutile TiO₂ (r-TiO₂) was obviously higher than that on the anatase TiO₂ (a-TiO₂) via the qualification of the X-ray diffraction extrapolation method, presenting a like-disperses-like rule. Combined hydrogen temperature-programmed reduction and X-ray photoelectron spectroscopy results revealed that stronger interaction occurred between the supported SnO₂ and the r-TiO₂ than and the a-TiO₂, thus resulting in higher SnO₂ dispersion on the r-TiO₂. The SnO₂/r-TiO₂ catalysts exhibited higher CO activity than the SnO₂/a-TiO₂ catalysts with the same SnO₂ loadings, verified that the supported SnO₂ and the support sharing a crystalline phase is favorable to achieve the more active dispersed component. The CeO₂ monolayer dispersion capacities on cubic c-ZrO₂ and monoclinic m-ZrO₂ supports further confirmed the universality of the like-disperses-like rule for oxide–oxide systems independent on preparation methods. By comparing a series of oxide–oxide systems, the like-disperses-like rule involved not only the crystalline phase and lattice matching, but also M–O bond characteristics of two oxides.