Controlled spillover in a single catalyst pellet: Rate modification, mechanism and relationship with electrochemical promotion

The effect of spillover processes on the activity of a catalyst system consisting of a mixed oxygen ion and electronic conducting support La0.6Sr0.4Co0.2Fe0.8O3−δ and a metal catalyst (Pt) were investigated. Two types of model single-pellet catalysts were used employing Pt deposited on both sides of a dense LSCF disc pellet. One of these single pellets employed highly disperse, physically non-continuous Pt, in contrast to studies on electrochemical promotion, while the other used a low dispersion continuous film. Driving forces for promoter migration were controlled through the manipulation of the oxygen chemical potential difference across the membrane. Catalyst rate modification was observed in all cases. However, it was found that there is a complex relationship between the rate modification, the driving forces for spillover and the geometrical arrangement of the catalyst on the support (i.e. catalyst dispersion).

Graphical abstractThe effect of spillover processes on the activity of a catalyst system consisting of a mixed oxygen ion and electron conducting support (La0.6Sr0.4Co0.2Fe0.8O3−δ) and a metal catalyst (Pt) were investigated. Driving forces for promoter migration were controlled through the manipulation of the oxygen chemical potential difference across the catalyst which was in the form of a pellet membrane. It was found that there is a complex relationship between the rate modification through spillover, the driving forces for spillover and the geometrical arrangement of the catalyst on the support (i.e. catalyst dispersion).Figure optionsDownload full-size imageDownload high-quality image (60 K)Download as PowerPoint slideHighlights► Effect of spillover on a model Pt–La0.6Sr0.4Co0.2Fe0.8O3−δ catalyst pellet studied. ► Continuous catalyst film rate promotion observed as a result of spillover. ► Non-reversible promotion indicative of new higher reactivity state. ► First study of EPOC on a non-continuous Pt catalyst in a simple two-phase system. ► Dispersed catalyst Pt (non-continuous) classical EPOC behaviour.