Pt/ZrO2/TiO2 catalysts for selective hydrogenation of crotonaldehyde:: Tuning the SMSI effect for optimum performance

Gas phase hydrogenation of crotonaldehyde was performed over Pt/ZrO2/TiO2 catalysts with different zirconia loadings, subjected to low- and high-temperature calcination (200 and 400 degrees C) and a range of reduction temperatures (200-600 degrees C). Pt/TiO2 was used as reference system. The catalysts were characterised by TPR, XPS, SEM, HR TEM, TOF-SIMS and H-2, O-2 and CO chemisorption after different stages of thermal pretreatments. The relationship between catalytic activity, selectivity towards crotyl alcohol and physicochemical properties of the catalysts was examined. The catalyst containing 30% ZrO2 in the support, calcined at 200 degrees C and reduced at 500 degrees C showed the highest selectivity (50%) while retaining good activity. The explanation of those properties was proposed, involving the mutually opposing action of two factors - presence of ZrO2 and 'permeability' of Pt phase for TiOx migration - in controlling of the SMSI effect. (c) 2007 Elsevier B.V. All rights reserved.