Structural analysis of a Pt Pd core-shell/Al-SBA-15 catalyst synthesized by the solid-state impregnation route

Abstract

Abstract Synthesis of a bimetallic catalyst of Pt core-Pd shell nanoparticles impregnated onto Al-SBA-15 particles is reported. The simultaneous impregnation of metals was performed by a route modified of the solid state impregnation method. The metal load impregnated onto alumina-grafted SBA-15 particles of atomic ratio Si/Al ≅ 13, was 1.3 wt% with a Pd/Pt atomic ratio of 1.8. Thickening of the hexagonal arrangement pore walls without mesopores plugging by the metal impregnation was evidenced. In situ FTIR spectroscopy of adsorption/desorption of pyridine in the samples revealed Al-SBA-15 particles with a small amount of moderate-strong Bronsted acid sites in the form of Si O(H) Al bridges and with the Pd and Pt incorporation suggests Si O(H) Al-M (M = Pd, Pt) bridges. The bimetallic nanoparticles were well dispersed onto the Al-SBA-15 particles. The average size calculated was around 2.4 ± 0.7 nm and their structure was Pt Pd core-shell type according to Nanoprobe EDX line scan and atomic resolution image analysis. A big population of structural and surface defects in the nanoparticles was revealed, too.