Operando Analysis of Industrially Relevant Rh-P catalysed Olefin Hydroformylation by Multi-Nuclear FlowNMR Spectroscopy

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In this project we will use operando FlowNMR as a tool to gain unprecedented levels of insight into hydroformylation catalysis mediated by rhodium-phosphine complexes. Although olefin hydroformylation is a well-established technology and with >10 Mt p.a. one of the largest homogeneously catalysed processes in the world, there still are many application-relevant questions around the origin of chemo-, regio- and enantioselectivity as well as dormant and deactivated catalyst species leading to the formation of unwanted side-products in this chemistry. This is particularly true for some of the more 'unusual' phosphines such as Evonik's bulky phosphonites and bis-phosphites and as well as Eastman's fluoro-phosphites that give high levels n-selectivity under surprisingly mild conditions. Understanding how and why they differ from the classical aryl-phosphine Wilkinson systems promises access to design principles that will allow the development of improved systems that be tailored to a desired product selectivity, and thus form the basis of new, cleaner and more efficient hydroformylation processes.We will use Bath's unique capabilities in operando FlowNMR spectroscopy to follow catalyst activation, turnover, and recovery & reuse by rapid and quantitative in-situ 1H, 19F and 31P FlowNMR. Multi-dimensional correlation spectroscopy, selective decoupling, hetero-nuclear diffusion analysis and polarisation transfer experiments in conjunction with selective excitation of low intensity signals will give a comprehensive picture of catalyst speciation that may be directly correlated with the overall reaction progress. A particular focus will lie on identifying pathways that lead into dormant species, irreversible deactivation and unwanted side-product formation, all important considerations for large-scale application. Spectral traces will be analysed by Reaction Progress Kinetic Analysis (RPKA) using Variable Time-Normalization (VTN) to establish solid kinetic descriptors for all relevant parameters describing the behaviour of the catalytic system.