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Hydrodynamic effects on three phase micro-packed bed reactor performance – gold-palladium catalysed benzyl alcohol oxidation

Al-Rifai, N; Galvanin, F; Morad, M; Cao, E; Cattaneo, S; Sankar, M; Dua, V; ... Gavriilidis, A; + view all (2016) Hydrodynamic effects on three phase micro-packed bed reactor performance – gold-palladium catalysed benzyl alcohol oxidation. Chemical Engineering Science , 149 pp. 129-142. 10.1016/j.ces.2016.03.018. Green open access

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Abstract

The hydrodynamics of a three-phase micro-packed bed reactor and its effect on catalysed benzyl alcohol oxidation with pure oxygen were studied in a silicon-glass microstructured reactor. The microreactor was operated at 120 °C and 1 barg and contained a channel with a 300 μm ×600 μm cross section, packed with 1 wt% Au-Pd/TiO2 catalyst 65 μm in average diameter. Improvements in the conversion of benzyl alcohol and selectivity to benzaldehyde were observed with increasing gas-to-liquid ratio, which coincided with a change in the flow pattern from a liquid-dominated slug to a gas-continuous regime. The observed enhancement is attributed to improved external mass transfer, associated with an increase in the gas-liquid interfacial area and reduction in the liquid film thickness that occur with gradual changes in the flow pattern. A maximum selectivity of 93% to benzaldehyde was obtained under partial wetting - which introduced the added benefit of direct gas-solid mass transfer - outperforming the selectivity in a conventional glass stirred reactor. However, this was at the expense of a reduction in the conversion. A response surface model was developed and then used to predict optimal operating conditions, which were in the gas-continuous flow regime. This corresponded to relatively high gas flow rate in conjunction with moderate liquid flow rate ensuring sufficient catalyst wetting with a thin film to reduce transport resistances.

Type: Article
Title: Hydrodynamic effects on three phase micro-packed bed reactor performance – gold-palladium catalysed benzyl alcohol oxidation
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.ces.2016.03.018
Publisher version: http://dx.doi.org/10.1016/j.ces.2016.03.018
Language: English
Additional information: This is an Open Access article published under a Creative Commons Attribution 4.0 International licence (http://creativecommons.org/licenses/by/4.0/).
Keywords: Multiphase microreactor; Hydrodynamics; Multiphase flow; Aerobic oxidation; Gold/palladium catalyst; Response Surface Methodology
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1482107
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