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Operando Magnetic Resonance Studies of Phase Behaviour and Oligomer Accumulation Within Catalyst Pores During Heterogeneous Catalytic Ethene Oligimerization

Baker, L; Renshaw, M P; Mantle, M D; Sederman, A J; Wain, A J; Gladden, L F (2018) Operando Magnetic Resonance Studies of Phase Behaviour and Oligomer Accumulation Within Catalyst Pores During Heterogeneous Catalytic Ethene Oligimerization. Applied Catalysis A - General, 557. pp. 125-134.

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Abstract

Two-dimensional 1H magnetic resonance imaging and spatially-resolved 1H magnetic resonance spectroscopy and diffusion measurements were recorded as a function of time-on-stream within a fixed-bed reactor to provide direct measurements of the progress of the heterogeneous catalytic oligomerization of ethene occurring over a 1 wt% Ni-Al2O3-SiO2 catalyst. The catalyst bed was of internal diameter 2 cm; magnetic resonance measurements were recorded over a bed length of 5.5 cm. Experiments were conducted at a temperature and pressure of 110 °C and 29 bara, respectively, with continuous downflow of ethene at a flowrate of 0.78 L h-1. During conversion the accumulation of 1H-containing species within the catalyst pellets was imaged, and spatiallyresolved 1H NMR spectra were recorded at 1mm intervals along the length of the reactor. Diffusion-filtered 1D chemical shift imaging was used to discriminate between gas- and liquid-phase species along the length of the reactor at 1mm intervals. Finally, spectrally-encoded pulsed field gradient measurements of molecular diffusion were employed to infer the molecular composition of the gas and liquid phases and to identify populations of these phases inside and external to the pore space of the catalyst pellets; these measurements were spatially resolved along the length of the reactor, with data being averaged over sections of height 4 mm. The results are consistent with oligomers of carbon number C20 and greater existing within the pores of the catalyst pellets which act to block the pore space, thereby deactivating the catalyst.

Item Type: Article
Subjects: Advanced Materials > Electrochemistry
Divisions: Engineering, Materials & Electrical Science
Identification number/DOI: 10.1016/j.apcata.2018.03.011
Last Modified: 18 Jun 2018 13:32
URI: http://eprintspublications.npl.co.uk/id/eprint/7953

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