CHARACTERISTICS OF TiO2 SUPPORTED PT-BASED CATALYSTS PREPARED BY FLAME SPRAY PYROLYSIS IN HYDROGENATION OF 3-NITROSTYRENE

Abstract

The liquid-phase selective hydrogenation of 3-nitrostyrene was investigated over nanocrystalline Pt/TiO2 ,PtCo/TiO2 and PtCe/TiO2 catalysts synthesized by the single-step flame spray pyrolysis (FSP) method. The obtained powder was characterized by N2 physisorption, X-ray diffraction (XRD), CO pulse chemisorption, transmission electron spectroscopy (TEM), temperature program reduction (TPR), and infrared spectroscopy of adsorbed CO (CO-IR). For Pt/TiO2 catalyst, the catalyst performances in terms of both hydrogenation activity and selectivity to vinylaniline (VA) improved by reduction at high temperature (200-600 ◦C). Compared to the FSP-made catalysts (F-Pt/Ti), the Pt/TiO2 obtained by conventional impregnation (I-Pt/Ti) on a sol-gel TiO2 contained higher amount of rutile phase composition and exhibited much lower Pt dispersion and hydrogenation activity. For PtCo/TiO2 and PtCe/TiO2 catalysts were prepared by the single step flame spray pyrolysis with Co and Ce loadings varied at 0-1.5 wt%. The addition of Co and Ce led to higher amount of Pt terrace atoms being formed on the catalyst surface which promoted the selectivity towards ethylnitrobenzene. Nevertheless, the positive effect of Co and Ce addition can be observed when the catalysts were reduced at 500oC , suggesting the modification of Pt surface by the decoration of TiO2.