UK Catalysis Hub


Real time observation of the evolution of catalyst nanostructure

Prof. Andrew M. Beale

Understanding structure-activity relationships in heterogeneous catalysis is critical for realising why catalysts work or fail. Catalysts are highly responsive to their environment with their structure evolving, often quite significantly, in the early stages of catalytic activity (induction period) before reaching steady-state. The importance of this evolution can be put into context of catalytic activity by studying catalysts using X-ray methods applied under operando conditions (i.e. the catalytic activity is verified during the X-ray measurement). In this presentation I will show some recent results obtained on Mo-ZSM-5 catalysts used in the non-oxidative conversion of methane to aromatics; a technology that has much potential yet is beset with technical failings. Our experiments allowed us to track the evolution of the active Mo environment and to conclude that the formation of molecular and sintered Mo carbides is respectably, both necessary and unavoidable. In a second example, I show how supported Co nanoparticles used in Fischer-Tropsch synthesis evolve either subtly or dramatically and how this shows a dependency on both particle size and support type.

Figure. The evolution of Mo in H-ZSM-5 during Methane Dehydroaromatization and its impact on product distribution and catalyst deactivation as revealed by XAFS and HRPD.