Steady-State and Transient Kinetic Studies of the Acetoxylation of Toluene over Pd–Sb/TiO2

• Published in: ACS catalysis 2016-07, Vol.6 (7), p.4621-4629
• Main Authors: Reining, Sven, Kondratenko, Evgenii V, Kalevaru, Narayana V, Martin, Andreas
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.6b00646

A combination of steady-state catalytic tests, transient studies with isotopic tracers, and kinetic modeling was used to derive detailed insights into the individual reaction pathways in the course of toluene acetoxylation over a Pd–Sb/TiO2 catalyst. This reaction can be considered as an environmentally friendly route for the production of benzyl alcohol. Benzyl acetate and benzaldehyde are the only products formed from toluene, while acetic acid gives CO2 in addition to benzyl acetate. The Arrhenius plots revealed apparent activation energies for formation of benzyl acetate and benzaldehyde of 24.9 and 27.5 kJ mol–1, respectively, thus, indicating that these products originate from the same surface intermediate, i.e. benzyl cation. The corresponding value for CO2 formation was 152.9 kJ mol–1. Transient isotopic studies and their kinetic evaluation demonstrated the participation of lattice oxygen and adsorbed oxygen species in activation of acetic acid, with the latter species favoring oxidation of the acid to CO2.