Issue 29, 2013

Evolution of active catalysts for the selective oxidative dehydrogenation of methanol on Fe2O3 surface doped with Mo oxide

Abstract

Iron molybdate catalysts are used for the selective oxidation of methanol to formaldehyde. In this paper we have attempted to understand what determines high selectivity in this reaction system by doping haematite with surface layers of Mo by incipient wetness impregnation. This works well and the Mo appears to form finely dispersed layers. Even very low loadings of Mo have a marked effect on improving the selectivity to formaldehyde. Haematite itself is a very poor catalyst with high selectivity to combustion products, whereas, when only 0.25 monolayers of Mo are deposited on the surface, formaldehyde and CO selectivities are greatly enhanced and CO2 production is greatly diminished. However, even with as much as seven monolayers of Mo dosed on to the surface, these materials achieve much less selectivity to formaldehyde at high conversion than do the industrial catalysts. The reason for this is that the Mo forms a ‘skin’ of ferric molybdate on a core of iron oxide, but does not produce a pure Mo oxide monolayer on the surface, a situation which is essential for very high yields of formaldehyde.

Graphical abstract: Evolution of active catalysts for the selective oxidative dehydrogenation of methanol on Fe2O3 surface doped with Mo oxide

Article information

Article type
Paper
Submitted
28 Jan 2013
Accepted
22 Mar 2013
First published
02 Apr 2013

Phys. Chem. Chem. Phys., 2013,15, 12056-12067

Evolution of active catalysts for the selective oxidative dehydrogenation of methanol on Fe2O3 surface doped with Mo oxide

M. Bowker, C. Brookes, A. F. Carley, M. P. House, M. Kosif, G. Sankar, I. Wawata, P. P. Wells and P. Yaseneva, Phys. Chem. Chem. Phys., 2013, 15, 12056 DOI: 10.1039/C3CP50399B

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