Reversible Transformations of Palladium-Indium Intermetallic Nanoparticles upon Repetitive Redox Treatments in H2/O2

The transformations of chemical states and structures occurring in the PdIn/Al2O3 catalyst upon redox treatments in different gaseous atmospheres at different temperatures are addressed by an assortment of in situ bulk- (XRD) and surface-sensitive (XPS and DRIFTS CO) techniques. Any desired state of the catalyst between two opposite extremes of highly dispersed oxide species and regularly ordered PdIn intermetallic compound could be set in fully controlled and reversible ways by selecting appropriate conditions for the reductive treatment starting from the fully oxidized state. Since mutual conversions of multi-atomic Pdn centers into single-site Pd-1 centers are involved in these transformations, the methodology could be used to find an optimum balance between the activity and selectivity of the catalytic system.

Automated summary

This study investigates the transformations of chemical states and structures in the PdIn/Al2O3 catalyst during redox treatments at different temperatures and in different gaseous atmospheres using various in situ techniques. The results show that it is possible to control and reverse the state of the catalyst between highly dispersed oxide species and regularly ordered PdIn intermetallic compound by selecting appropriate conditions for the reductive treatment. This transformation involves the conversion of multi-atomic Pdn centers into single-site Pd-1 centers and could be used to optimize the activity and selectivity of the catalytic system.