Since 1978, TiO
2-supported noble metals and related catalysts have been studied extensively in relation to SMSI (Strong Metal-Support Interaction). Initially, so-called “pill-box” structure model was proposed for SMSI, and widely accepted. This model stated that Pt hemisphere particle changes its morphology into thin pill-box, accompanied with direct chemical bond between Pt and Ti
+3 as a result of a partial reduction of TiO
2 during high temperature H
2 reduction. However, a recently proposed alternative model, i.e., “migration” model, has been replacing the above one. In the “migration” model, suboxide, TiOx, produced by reduction of support covers the metal surface, which is responsible for severe suppression of H
2 and CO chemisorption.
Many works have been done on the effect of SMSI upon such catalysis as hydrogenolysis, hydrogenation and dehydrogenation of hydrocarbons and CO hydrogenation, and discussed in relation to SMSI mechanism.
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