Low-Temperature Selective Oxidative Dehydrogenation of Cyclohexene by Titania-Supported Nanostructured Pd, Pt, and Pt–Pd Catalytic Films

0583593 - ÚFCH JH 2025 RIV US eng J - Journal Article
Vaidulych, Mykhailo - Yeh, L. - Y. - Hoehner, R. - Jašík, Juraj - Kadam, Shashikant Arun - Vorochta, M. - Khalakhan, I. - Hagen, J. - Vajda, Štefan
Low-Temperature Selective Oxidative Dehydrogenation of Cyclohexene by Titania-Supported Nanostructured Pd, Pt, and Pt–Pd Catalytic Films.
Journal of Physical Chemistry C. Roč. 128, č. 8 (2024), s. 3180-3192. ISSN 1932-7447. E-ISSN 1932-7455
EU Projects: European Commission(XE) 810310 - J. Heyrovsky Chair
Institutional support: RVO:61388955
Keywords : Aromatic compounds * Catalysts * Hydrocarbons
OECD category: Physical chemistry
Impact factor: 3.7, year: 2022
Method of publishing: Open access

Films of titania-supported monometallic Pd, Pt, and bimetallic Pt–Pd catalysts made of metallic nanoparticles were prepared by magnetron sputtering and studied in the oxidative dehydrogenation (ODH) of cyclohexene. Pd/TiOx and Pt–Pd/TiOx were found active at as low temperature as 150 °C and showed high catalytic activity with high conversion (up to 81%) and benzene selectivity exceeding 97% above 200 °C. In turn, the Pt/TiOx catalyst performed poorly with the onset of benzene production at 200 °C only and conversions not exceeding 5%. The activity of bimetallic Pt–Pd catalysts far exceeded all of the other investigated catalysts at temperatures below 250 °C. However, the production of benzene significantly dropped with a further temperature increase due to the enhanced combustion of CO2 at the expense of benzene formation. As in situ NAP-XPS measurement of the Pt–Pd/TiOx catalyst in the reaction conditions of the ODH of cyclohexene revealed Pd surface enrichment during the first temperature ramp, we assume that Pd surface enrichment is responsible for enhanced activity at low temperatures in the bimetallic catalyst. At the same time, the Pt constituent contributes to stronger cyclohexene adsorption and oxygen activation at elevated temperatures, leading to changes in conversion and selectivity with a drop in benzene formation and increased combustion to CO2. Both the monometallic Pd and the Pt–Pd-based catalysts produced a small amount of the second valuable product, cyclohexadiene, and below 250 °C produced only a negligible amount of CO2 (<0.2%). To summarize, Pd- and Pt–Pd-based catalysts were found to be promising candidates for highly selective low-temperature dehydrogenation of cyclic hydrocarbons that showcased reproducibility and stability after the temperature activation. Importantly, these catalysts were fabricated by utilizing proven methods suitable for large-scale production on extended surfaces.
Permanent Link: https://hdl.handle.net/11104/0351599