Issue 9, 2003

Mixed cobalt–iron oxide absorbents for low-temperature gas desulfurisation

Abstract

High surface area cobalt–iron oxides (with Co ∶ Fe ratios of [3 ∶ 1], [1 ∶ 1] and [1 ∶ 2]) have been prepared by the calcination of predominantly single-phase, coprecipitated hydrotalcite-type precursors prepared from mixed-Co2+–Fe3+ aqueous solutions. The oxide structures were all spinels; for the Co–Fe [3 ∶ 1] oxide, this was a Co3O4-type lattice, for the Co–Fe [1 ∶ 2] sample, it was a Fe3O4-type lattice and for Co–Fe [1 ∶ 1] an equal mix of the two was observed. The H2S uptake of all the oxides was tested at 303 K and the data correlated with sorbent preparation and characterisation. The Co–Fe [1 ∶ 1] oxide absorbed the most H2S before breakthrough and further studies into the preparation of this oxide showed that nitrate-free precursors produced at pH 7 and then aged for 30 minutes or more gave rise to the best oxide sorbents after calcination at 623 K rather than 723 K. These observations have been rationalised on the basis that these oxides had lower density and a greater mix of Co2+/3+ and Fe2+/3+ leading to more distortion of the parent oxide lattice. Increased H2S uptake was ascribed to more rapid ion diffusion through the sorbent lattice leading to enhanced replenishment of surface oxide.

Graphical abstract: Mixed cobalt–iron oxide absorbents for low-temperature gas desulfurisation

Supplementary files

Article information

Article type
Paper
Submitted
26 Mar 2003
Accepted
30 Jun 2003
First published
16 Jul 2003

J. Mater. Chem., 2003,13, 2341-2347

Mixed cobalt–iron oxide absorbents for low-temperature gas desulfurisation

T. Baird, K. C. Campbell, P. J. Holliman, R. Hoyle, G. Noble, D. Stirling and B. P. Williams, J. Mater. Chem., 2003, 13, 2341 DOI: 10.1039/B303449F

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