Preparation and characterization of TiO2 support for Pd catalysts: Application in hydrogenation of 4-carboxybenzaldehyde

The formed TiO2 supports were prepared by compression method and then used in the Pd/TiO2 catalytic hydrogenation of 4-carboxybenzaldehyde (4-CBA). Supports and catalysts were characterized by the intensity test, BET, XRD, SEM and ICP techniques. Results showed that the pore-forming agent can adjust both the specific surface and average pore diameter. The suitable content is 4 wt.%. Silicon additive inhibits the growth of TiO2 grain and the anatase-rutile phase transformation. Forming pressure brings out a certain crushing strength and pore characteristic. The crushing strength of support significantly increases with increasing support calcination temperature. However, the specific surface and pore volume decrease. The TiO2 support has the side crushing strength of 122 N/cm and the specific surface of 38 m(2)/g at the optimum preparation conditions of silicon additive of 4 wt.%, forming pressure of 150 MPa and calcination temperature of 700 degrees C. A series of Pd/TiO2 catalysts were prepared by incipient wetness of impregnation and liquid-phase chemical reduction method. On Pd/TiO2700 (Pd, 0.5 wt.%) catalyst, the 99.5% conversion of 4-CBA is obtained after reaction for 90 min at reaction temperature of 280 degrees C and hydrogen partial pressure of 0.6 MPa.