Size- and composition selected supported subnanometer Cu, Pd and CuPd clusters in the oxidative dehydrogenation of cyclohexene Stanislav Valtera 1 , Juraj Jašík 1 , Mykhailo Vaidulych 1 , Joanna Elżbieta Olszówka 1 , Muntaseer Bunian 2 , Yu Lei 2 , Avik Halder 3 , Hana Tarabková 4 , Magda Zlámalová 4 , Martin Jindra 4,5 , Ladislav Kavan 4 , Otakar Frank 4 , Stephan Bartling 6 , Štefan Vajda 1 1 Department of Nanocatalysis, J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Czech Republic, 2 Department of Chemical and Materials Engineering, The University of Alabama in Huntsville, USA, 3 Materials Science Division, Argonne National Laboratory, USA, 4 Department of Electrochemical Materials, J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Czech Republic, 5 Department of Physical Chemistry, University of Chemistry and Technology in Prague, Czech Republic, 6 Leibniz Institute for Catalysis (LIKAT), Germany Preceding studies performed on copper particles consisting of one to seven atoms supported on thin titania films made by atomic layer deposition identified the copper tetramer (Cu 4 ) the most active in the oxidative dehydrogenation (ODH) of cyclohexene to benzene [1], while also finding this tetramer to produce cyclohexadiene when supported on SiO 2 . However, the activity of the cluster on silica-support was about an order of magnitude lower than on titania. Motivated by these findings and earlier reports on highly active palladium clusters in the oxidative dehydrogenation of cyclohexane [2], the focus turned to identifying new cluster-support combinations for the ODH of cyclohexene with tunable selectivity between producing benzene or cyclohexadiene. Select tetramer- based size- and composition selected Cu m Pd n (m+n=4) clusters supported on zirconia and ultrananocrystalline diamond were investigated with the goal to assess the effect of replacing atoms of copper in Cu 4 in an atom-by- atom fashion along with the effect of the two supports. The obtained results demonstrate that the use of these two control knobs, i.e. the atomic composition of the bimetallic CuPd tetramer and the support allow for fine-tuning both the activity and the selectivity of these catalysts, while suppressing the combustion channel: Tetramers with prevailing Pd content are found to be the most active and dominantly producing benzene, with increasing number of Cu atoms the selectivity gradually shifts towards cyclohexadiene [3]. References 1. “Atom by Atom Built Subnanometer Copper Cluster Catalyst for the Highly Selective Oxidative Dehydrogenation of Cyclohexene”,S. Valtera,J. Jašík,M. Vaidulych,J. E. Olszówka,M. Zlámalová,H. Tarábková, L. Kavan, andŠ.Vajda, J. Chem. Phys. 156 , 114302 (2022), DOI:10.1063/5.0065350 2. “Oxidative Dehydrogenation of Cyclohexane by Cu vs Pd Clusters: Selectivity Control by Specific Cluster Dynamics”, A. Halder, M.-A. Ha, H. Zhai, B. Yang, M. J. Pellin, S. Seifert, A.N. Alexandrova, S.Vajda, ChemCatChem. 12 , 1307–1315, (2020) DOI: 10.1002/cctc.201901795, front cover 3. “Oxidative dehydrogenation of cyclohexene on atomically precise subnanometer Cu 4-n Pd n (0≤n≤4) tetramer clusters: The effect of cluster composition and support on performance”, J. Jašík, S. Valtera, M. Vaidulych, M.Bunian , Y. Lei, A. Halde 3 , H. Tarabková, M. Jindra, L. Kavan, O. Frank, S. Bartling, Š. Vajda, Faraday Discussions (2022), accepted
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