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Selective oxidation of methanol on mixed oxide catalysts

Yaseneva, Polina 2011. Selective oxidation of methanol on mixed oxide catalysts. PhD Thesis, Cardiff University.

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Abstract

In the present work selective oxidation of methanol over the model Mo/Fe2O3 and Mo/Co(Zn) Fe2O4 systems has been investigated. It was shown that pure iron oxide and cobalt ferrite combust methanol to carbon dioxide and water. When molybdenum is loaded on the surface of iron oxide and calcined at 500 C, this leads to the formation of iron molybdate surface layer over Fe2C>3 core, which significantly changes selectivity in methanol oxidation towards partial oxidation products. The neighbouring Fe-Mo and Mo-Mo pairs of iron molybdate layer are responsible for the formation of carbon monoxide and formaldehyde respectively. According to XRD, Raman and XPS data, dosing of molybdenum onto the cobalt ferrite surface results in the formation of a mixed layer consisting of cobalt molybdate, iron molybdate and molybdena phases. Oxidation of methanol over Mo/CoFe2O4 results in the formation of a mixture of CO and CO2 with small traces of formaldehyde. CO is produced on mixed Fe-Mo and Co-Mo sites at temperatures above 220 C, whereas CO2 is mainly produced at lower temperatures and low oxygen conversion due to oxidation of CO by highly reactive traces of pure cobalt ferrite or cobalt molybdate present on the surface. Methanol oxidation was used as a model reaction to establish whether there is a relationship between catalytic activity and selectivity, and magnetic properties of catalysts. The catalytic behaviour of the pure and Mo impregnated ZnxCoi-xFe2O4 systems in the vicinity of Curie point was studied. Curie temperature of the material and the nature of Curie transition were adjusted varying Zn content and sample calcination temperature.

Item Type: Thesis (PhD)
Status: Unpublished
ISBN: 9781303196539
Funders: Cardiff University, ORSAS
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:30
URI: http://orca-mwe.cf.ac.uk/id/eprint/54464

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