Selective hydrogenation using palladium bioinorganic catalyst

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Colleges, School and Institutes

Abstract

Palladium bioinorganic catalyst (bio-Pd) was manufactured using bacteria (Desulfovibrio desulfuricans and Escherichia coli) via the reduction of Pd(II) to bio-scaffolded Pd(0) nanoparticles (NPs). The formed Pd NPs were examined using electron microscopy and X-ray powder diffraction methods: a loading of 5 wt% Pd showed an average particle size of ~4 nm. The catalytic activities of the prepared bio-Pd NPs on both bacteria were compared in two hydrogenation reactions with that of a conventionally supported Pd catalyst (Pd/Al2O3). Concentration profiles of the different hydrogenation products were fitted using a Langmuir-Hinshelwood expression. In 2-pentyne hydrogenation, 5 wt% PdE.coli achieved 100% of 2-pentyne conversion in 20 mins and produced 10.1 ± 0.7 × 10-2 mol L-1 of desired cis-2-pentene, in contrast 5 wt% Pd/Al2O3 yielded 6.5 ± 0.4 × 10-2 mol L-1 of cis-2-pentene after 40 mins. In the solvent-free hydrogenation of soybean oil, the use of 5 wt% PdE.coli yielded cis-C18:1 of 1.03 ± 0.04 mol L-1 and trans-C18:1 of 0.26 ± 0.03 mol L-1 (~50% less of the latter than 5 wt% Pd/Al2O3) after 5 h. Similar results were obtained using bio-PdE.coli and bio-PdD.desulfuricans. Bio-Pd was concluded to have the advantage of a lower cis-trans isomerisation in hydrogenation of alkyne/alkenes. Hence biomanufacturing is an environmentally attractive, scalable and facile alternative to conventional heterogeneous catalyst for application in industrial hydrogenation processes. D. desulfuricans is inconvenient to grow at scale but wastes of E. coli are produced from various industrial processes. 'Second life' (i.e. recycled from a pilot scale biohydrogen production process) E. coli cells were used to make bio-Pd catalysts. Although 'bio-Pdsecondlife' gave a slower conversion rate of 2-pentyne and soybean oil compared to bio-Pd from purpose-grown cells it showed a higher selectivity to the cis-isomer product.

Details

Original languageEnglish
Pages (from-to)108-122
Number of pages15
JournalApplied Catalysis B: Environmental
Volume199
Early online date3 Jun 2016
Publication statusPublished - 15 Dec 2016

Keywords

  • 2-pentyne, Bacteria, Hydrogenation, Isomerisation, Palladium, Soybean oil