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Magnetic Resonance Studies of Three-Phase Heterogeneous Catalytic Hydrogenation Reactions https://doi.org/10.17863/CAM.118209 Petch, Kathryn Mantle, Mick The work described in this thesis focuses on the development and implementation of nuclear magnetic resonance (NMR) methods to study heterogeneously catalysed hydrogenation reactions, under continuous reaction conditions. The techniques developed aimed to elucidate the chemical composition inside the reactor and to provide a better understanding of the interactions of the reaction species with the catalyst material and reactor. Bulk and spatially resolved 2D NMR relaxation and diffusion measurements were used to characterize reaction species. Experiments were carried out on the species in their pure state as bulk liquids and imbibed in the catalyst material (Pd/Al2O3). Single component liquids as well as mixtures were investigated to understand their behaviour inside the porous catalyst material. A peak fitting method was developed to facilitate the quantification of species within a reactor from chemical shift imaging (CSI). This method helped to identify overlapping peaks caused by the broadening effects of liquids imbibed within porous catalyst materials. The method was tested on known samples of reaction species involved in the hydrogenation of styrene and phenylacetylene, to understand the accuracy and reliability of the procedure. Hydrogenation reactions of styrene and phenylacetylene were carried out in a trickle bed reactor (TBR), under varying hydrogen concentrations. The catalyst bed was analysed using the 2D relaxation and diffusion measurements, as well as CSI. The peak fitting method was applied to CSI data of the catalyst bed to understand the effect of hydrogen concentration on the composition in the catalyst bed. The in situ data was also compared with off-line spectral data for the reaction outlet products. This work demonstrates that a peak-fitting algorithm, constrained by system-specific knowledge, can successfully identify chemical species at various locations within a reactor from CSI data of a two-stage hydrogenation reaction. This approach helps overcome the challenges of line broadening and peak overlap commonly encountered with species confined in porous materials. This, in combination with the development of state-of-the-art spatially resolved T₁–T₂ and D–T₂ experiments, expands the NMR toolkit for characterizing and studying continuous three-phase catalytic reactions. University of Cambridge 2025-01-24 Thesis Doctoral Doctor of Philosophy (PhD) eng https://www.repository.cam.ac.uk/handle/1810/384083 embargo 2026-05-15 https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/f3574184-5ab9-4110-be41-45784c51666a/download e89e8f799c4d12aca903599ae96acbaa https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/01087e7b-19a8-410e-9b67-91ddc7de31a2/download 87eda9de84448d1f82354d60eee3eb5f http://purl.org/NET/rdflicense/allrightsreserved 2D correlation NMR catalytic reaction Chemical Shift Imaging Deconvolution diffusion D-T2 hydrogenation in situ Magnetic Resonance NMR Pd/Al2O3 Peak fitting Phenylacetylene hydrogenation Porous media relaxation Spatially resolved NMR Styrene hydrogenation T1-T2 Three-Phase Trickle bed reactor