In Situ Dispersion of Palladium on TiO2 During Reverse Water–Gas Shift Reaction: Formation of Atomically Dispersed Palladium. (11th August 2020)

• Record Type: Journal Article
• Authors: Nelson, Nicholas C.; Chen, Linxiao; Meira, Debora; Kovarik, Libor; Szanyi, János
• Is Part Of: Angewandte Chemie. Volume 132:Number 40(2020)
• Page Start: 17810
• Page End: 17816
• Publication Date: 2020-08-11
• Subjects: in situ metal dispersion -- Pd1-TiO2 -- reverse water–gas shift -- thermodynamic stability; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202007576
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The application of single‐atom catalysts (SACs) to high‐temperature hydrogenation requires materials that thermodynamically favor metal atom isolation over cluster formation. We demonstrate that Pd can be predominantly dispersed as isolated atoms onto TiO2 during the reverse water–gas shift (rWGS) reaction at 400 °C. Achieving atomic dispersion requires an artificial increase of the absolute TiO2 surface area by an order of magnitude and can be accomplished by physically mixing a precatalyst (Pd/TiO2 ) with neat TiO2 prior to the rWGS reaction. The in situ dispersion of Pd was reflected through a continuous increase of rWGS activity over 92 h and supported by kinetic analysis, infrared and X‐ray absorption spectroscopies and scanning transmission electron microscopy. The thermodynamic stability of Pd under high‐temperature rWGS conditions is associated with Pd‐Ti coordination, which manifests upon O‐vacancy formation, and the artificial increase in TiO2 surface area. Abstract : Dilution of Pd/TiO2 with neat TiO2 results in the formation of atomically dispersed Pd under reverse water–gas shift (rWGS) reaction conditions at 400 °C and a several‐fold increase in activity.