Morphological effect of lanthanum-based supports on the catalytic performance of Pt catalysts in crotonaldehyde hydrogenation

摘要

Rod-like and particle-like La2O2CO3 and La2O3 were obtained via morphology-preserved thermal transformation of the La(OH)(3) precursors. La2O2CO3- and La2O3-supported Pt catalysts were prepared by impregnation method and tested in the liquid-phase crotonaldehyde hydrogenation reaction. The textural and physicochemical properties of the samples were studied by a series of techniques including XRD, TG-DSC, N-2 adsorption-desorption, TEM and HRTEM, IR spectrum, H-2-TPD, and H-2-TPR. Even after 600 A degrees C reduction, Pt particles of about 0.8-2.8 nm interplayed with support surface to form Pt-doped interface, thereby preventing the catalysts from migration and affording a high dispersion of platinum. The specific exposed crystal-facets and surface oxygen species depending on the shape of the support affected the preferential deposition of Pt species and the metal-support interaction. Thus, Pt catalysts performed different physicochemical properties and catalytic performance relying on the morphology and structure of the supports. During the cycle experiment, severe deactivation was observed for NP-supported catalysts with an increased selectivity due to the aggregation and growth of Pt particles. Meantime, the NR-supported catalysts retained relatively high reactivity as a consequence of the crystal-facet confinement of rod-shaped lanthanum supports.