CO oxidation over platinum-ceria catalysts -- Structural dynamics and reaction mechanisms
This work aims at understanding the catalytic function of platinum highly dispersed onto ceria, which is a reducible support. The kinetic behaviours during catalytic extinction and reaction orders have been experimentally determined using a fixed-bed flow reactor. To explore the structure-function relationships, operando infrared and X-ray absorption spectroscopy have been used. Also, detailed reaction pathways have been simulated using kinetic Monte Carlo with kinetic parameters determined from ab initio calculations.
The CO oxidation kinetics for Pt/ceria is qualitatively different from that of reference Pt/alumina. The extinction profile for Pt/ceria catalyst exhibits a smooth decay in CO conversion rather than a stepwise drop as for the Pt/alumina catalyst. This is due to the two supports modifying the Pt particles differently as well as complementary reaction paths towards CO2 facilitated by boundary sites only for the Pt/ceria catalyst. Furthermore, operando spectroscopy reveals that the Pt particles bind strongly with ceria showing an unaltered Pt-O bond distance of 2 Å during catalytic extinction. Although difficult to experimentally determine, charge transfer from Pt particles to ceria supplemented with reverse spillover of ceria lattice oxygen to the vicinity of Pt particles likely occur.
Chalmers, Kemi och kemiteknik, Tillämpad kemi
Mengqiao Di, Kerry Simmance, Andreas Schaefer, Yanyue Feng, Felix Hemmingsson, Magnus Skoglundh, David Thompsett, Lucy Idowu Ajakaiye Jensen, Sara Blomberg and Per-Anders Carlsson, Dynamics of small platinum particles obscured by support interactions
KB-10:an, Kemigården 4, Chalmers.
Opponent: Anders Hellman, Chalmers University of Technology, Sweden