The effect of titania polymorph on the strong metal-support interaction of Pd/TiO2 catalysts and their application in the liquid phase selective hydrogenation of long chain alkadienes

• DOI: 10.1016/j.molcata.2004.02.007
• Publication Date: 2004-03-20T11:12:07Z
• Authors: Yuanzhi Li; Bolian Xu; Yining Fan; Ninyuen Feng; Anding Qiu; Jianwen Miao Jie He; Hanpei Yang; Yi Chen
• Keywords: Rutile

Abstract In situ EPR and IR investigation by using CO as probe molecules show that even pre-reduced by H 2 at lower temperature results in SMSI for anatase titania supported palladium catalyst, but not for rutile titania supported palladium catalyst, which is attributed that the Ti 3+ ions produced by reduction of Ti 4+ are fixed in the surface lattice of TiO 2 , as rutile titania is more thermodynamically and structurally stable than anatase titania so that the Ti 3+ ions fixed in the surface lattice of anatase TiO 2 is easier to diffuse to surface of palladium particle than one in the surface lattice of rutile TiO 2 . Anatase titania supported palladium catalyst 0.075% Pd/TiO 2 (A) pre-reduced by H 2 at lower temperature has higher selectivity of alkenes for the liquid phase selective hydrogenation of long chain alkadienes than rutile titania supported palladium catalysts 0.075% Pd/TiO 2 (R). For titania (rutile or anatase) supported palladium catalysts, the elevation of pre-reduction temperature from 200 to 450 °C gives rise to sharp change of catalytic properties, especially for selectivity of alkenes. The very different catalytic properties between 0.075% Pd/TiO 2 (R) and 0.075% Pd/TiO 2 (A) catalyst pre-reduced at lower temperature, and the rapid increasing of selectivity of 0.075% Pd/TiO 2 (A) and 0.075% Pd/TiO 2 (R) with the elevation of pre-reduction temperature are reasonably explained by the presence of SMSI both for anatase titania supported palladium catalyst pre-reduced at lower temperature, and titania (rutile and anatase) supported palladium catalyst pre-reduced at higher temperature.