title: Sum frequency generation vibrational spectroscopy of 1,3-butadiene hydrogenation on 4 nm Pt@SiO2, Pd@SiO2, and Rh@SiO2 core-shell catalysts.
abstract: 1,3-Butadiene (1,3-BD) hydrogenation was performed on 4 nm Pt, Pd, and Rh nanoparticles (NPs) encapsulated in SiO2 shells at 20, 60, and 100 °C. The core-shells were grown around polyvinylpyrrolidone (PVP) coated NPs (Stöber encapsulation) prepared by colloidal synthesis. Sum frequency generation (SFG) vibrational spectroscopy was performed to correlate surface intermediates observed in situ with reaction selectivity. It is shown that calcination is effective in removing PVP, and the SFG signal can be generated from the metal surface. Using SFG, it is possible to compare the surface vibrational spectrum of Pt@SiO2 (1,3-BD is hydrogenated through multiple paths and produces butane, 1-butene, and cis/trans-2-butene) to Pd@SiO2 (1,3-BD favors one path and produces 1-butene and cis/trans-2-butene). In contrast to Pt@SiO2 and Pd@SiO2, SFG and kinetic experiments of Rh@SiO2 show a permanent accumulation of organic material.
authors.affiliation: Chemical Sciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: James M
authors.initials: JM
authors.lastname: Krier
authors.forename: William D
authors.initials: WD
authors.lastname: Michalak
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Cai
authors.forename: Lindsay
authors.initials: L
authors.lastname: Carl
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Komvopoulos
authors.forename: Gabor A
authors.initials: GA
authors.lastname: Somorjai
keywords: 1,3-Butadiene hydrogenation; core−shell nanoparticles; surface vibrational spectroscopy