Harnessing reactive radical intermediates to design new and more sustainable catalysts

Project overview

Film-electrochemical electron paramagnetic resonance spectroscopy (FE-EPR) is a transformative new experimental technique developed in the Roessler group that enables detailed insight into catalytic reactions by detecting and interrogating unpaired electrons. In this project and as part of the rEaCt CDT program, we will (1) develop and design software and hence optimally harness information from FE-EPR (with Alex Ganose), (2) engineer a user-friendly and widely applicable set-up (with Klaus Hellgardt), (3) design and screen novel working electrode materials and (4) apply FE-EPR to industrially relevant catalytic reactions (with Syngenta), focussing on TEMPO-catalysed alcohol oxidation, Cu-catalysed radical rearrangements and organic radical intermediate formation, stability and characterisation.

Detailed Description

Numerous catalytic reactions proceed via redox processes and hence short-lived radical intermediates. Yet, structure and reactivity investigations of redox-active catalysts are typically not directly connected. Hence, the mechanism of these catalytic reactions is often poorly understood, and few catalysts are designed or optimised based on detailed mechanistic understanding. An improved mechanistic understanding will support development and implementation of novel processes and allow optimisation of economic factors but importantly sustainability. These sustainability advantages could arise from switching from a thermal to radical mediated process, migration away from Pt group metal catalysts or an improved conceptualisation of waste strategies. For example, Cu-catalysts have a much higher natural abundancy and improved sustainability footprint compared to Pd, but transformation, particularly radical mediated transformations are much less well understood. TEMPO-catalysts are widely utilised but impurities generated from side reaction with terminal oxidants (e.g. bleach) and TEMPO catalysts require careful design and management of waste streams. A better understanding would allow mitigation of these issues through surface-bound catalysts, process design and upstream management. 

Film-electrochemical electron paramagnetic resonance spectroscopy (FE-EPR) is a new technique^1,2 that can provide a high level of mechanistic insight into reactions of surface-bound catalysts that proceed via radical intermediates. In addition, unlike standard (continuous-wave) EPR, pulse EPR spectroscopy can provide detailed insight into the nature and hence reactivity of radicals generated³ but has not been applied to either TEMPO- or Cu-catalysed industrial transformations.

In this collaborative and interdisciplinary project you will (1) engineer an FE-EPR set-up and develop material screening and data analysis programs that widen the scope and impact of this new technique, (2) apply the FE-EPR set-up to industrially important reactions, and (3) extend FE-EPR to include pulse EPR to provide detailed information on the electronic nature of key paramagnetic intermediates.

About the student

We are looking to recruit an outstanding Masters level graduate in Chemistry, Chemical Engineering or a related subject. You should have strong analytical skills and a keen interest in developing new methodology in a multidisciplinary project that spans from physical chemistry to organic chemistry and chemical engineering. Excellent training opportunities are available as part of the rEaCt CDT program, where you will be joining a cohort of highly motivated students. The Molecular Sciences Research Hub, the new research home for the Department of Chemistry at Imperial’s White City campus, provides access to top research facilities, including the Centre of Pulse EPR, PEPR.