New approaches to deliver high surface area Exsolution Catalysts
New approaches to deliver high surface area Exsolution Catalysts
Johnson Matthey co-funded project with EAsiCAT
4 year PhD with standard stipend
This project will address catalytic approaches to air pollution remediation. The materials composition, the intended nanostructures and the coating concept for exsolution materials are all highly novel. This project offers new highly active catalysts with reduced PM loading and high stability. The collaboration originates in a collaboration involving an important report of Pt exsolution catalysts1.
Redox exsolution has recently been demonstrated to yield catalytic metallic nanoparticles that have strong support interaction, often being socketed. This process involves preparing precursors, typically titanate perovskites, where the precursor metal ion is dissolved in the support before it is exsolved on reduction. Both transition metals and platinum group metals have been exolved to demonstrate strong and stable catalytic activity for reactions such as CO oxidation, NOx removal and ammonia slip catalysis. An important limitation of such materials is low intrinsic surface area of the support which limits the possible catalytic activity. This occurs as the fabrication process generally necessitates high temperature solid state reaction significantly decreasing surface area.
Here we seek to coat a high surface area alumina support with the exsolving perovskite. Titanates tend to react with alumina supports and so are not ideal exsolution hosts in this scenario. Recent work has highlighted to possibility of exsolution from lanthanum aluminate perovskites and these seem well suited to deposition onto alumina based supports and monoliths. Co and Fe seem to exsolve particularly well, often in combination to yield nano-alloys. In this study we will seek to integrate Pt into such aluminate perovskites, targeting nanoparticle Pt exsolution. These structures will be characterised via XRD electron microscopy, BET and thermal analysis before being characterised for catalytic activity. Target reactions will include CO oxidation and NOx removal.
Figure 1 Pt exsolution from Calcium Titanate as applied to air clean-up