The University of Southampton
University of Southampton Institutional Repository

Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde

Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde
Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde
The performance of Mo-enriched, bulk ferric molybdate, employed commercially for the industrially important reaction of the selective oxidation of methanol to formaldehyde, is limited by a low surface area, typically 5-8 m(2) g(-1). Recent advances in the understanding of the iron molybdate catalyst have focused on the study of MoOx@Fe2O3 (MoOx shell, Fe2O3 core) systems, where only a few overlayers of Mo are present on the surface. This method of preparing MoOx@Fe2O3 catalysts was shown to support an iron molybdate surface of higher surface area than the industrially-favoured bulk phase. In this research, a MoOx@Fe2O3 catalyst of even higher surface area was stabilised by modifying a haematite support containing 5 wt% Al dopant. The addition of Al was an important factor for stabilising the haematite surface area and resulted in an iron molybdate surface area of ?35 m(2) g(-1), around a 5 fold increase on the bulk catalyst. XPS confirmed Mo surface-enrichment, whilst Mo XANES resolved an amorphous MoOx surface monolayer supported on a sublayer of Fe2(MoO4)3 that became increasingly extensive with initial Mo surface loading. The high surface area MoOx@Fe2O3 catalyst proved amenable to bulk characterisation techniques; contributions from Fe2(MoO4)3 were detectable by Raman, XAFS, ATR-IR and XRD spectroscopies. The temperature-programmed pulsed flow reaction of methanol showed that this novel, high surface area catalyst (3ML-HSA) outperformed the undoped analogue (3ML-ISA), and a peak yield of 94% formaldehyde was obtained at ?40 °C below that for the bulk Fe2(MoO4)3 phase. This work demonstrates how core-shell, multi-component oxides offer new routes for improving catalytic performance and understanding catalytic activity.
0301-7249
115-129
Chapman, Stephanie
02fa6ac4-c0e7-4cd3-8ffb-bf1c88cbfd45
Brookes, Catherine
fcbf76ed-9e86-4aea-b8f5-174607bae342
Bowker, Michael
c9ab10a5-d144-4533-bf6d-2fa16b669565
Gibson, Emma K.
738c74e4-ab68-42fe-bda8-9d4a43669b31
Wells, Peter
bc4fdc2d-a490-41bf-86cc-400edecf2266
Chapman, Stephanie
02fa6ac4-c0e7-4cd3-8ffb-bf1c88cbfd45
Brookes, Catherine
fcbf76ed-9e86-4aea-b8f5-174607bae342
Bowker, Michael
c9ab10a5-d144-4533-bf6d-2fa16b669565
Gibson, Emma K.
738c74e4-ab68-42fe-bda8-9d4a43669b31
Wells, Peter
bc4fdc2d-a490-41bf-86cc-400edecf2266

Chapman, Stephanie, Brookes, Catherine, Bowker, Michael, Gibson, Emma K. and Wells, Peter (2016) Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde. Faraday Discussions, 188, 115-129. (doi:10.1039/c5fd00153f). (PMID:27067956)

Record type: Article

Abstract

The performance of Mo-enriched, bulk ferric molybdate, employed commercially for the industrially important reaction of the selective oxidation of methanol to formaldehyde, is limited by a low surface area, typically 5-8 m(2) g(-1). Recent advances in the understanding of the iron molybdate catalyst have focused on the study of MoOx@Fe2O3 (MoOx shell, Fe2O3 core) systems, where only a few overlayers of Mo are present on the surface. This method of preparing MoOx@Fe2O3 catalysts was shown to support an iron molybdate surface of higher surface area than the industrially-favoured bulk phase. In this research, a MoOx@Fe2O3 catalyst of even higher surface area was stabilised by modifying a haematite support containing 5 wt% Al dopant. The addition of Al was an important factor for stabilising the haematite surface area and resulted in an iron molybdate surface area of ?35 m(2) g(-1), around a 5 fold increase on the bulk catalyst. XPS confirmed Mo surface-enrichment, whilst Mo XANES resolved an amorphous MoOx surface monolayer supported on a sublayer of Fe2(MoO4)3 that became increasingly extensive with initial Mo surface loading. The high surface area MoOx@Fe2O3 catalyst proved amenable to bulk characterisation techniques; contributions from Fe2(MoO4)3 were detectable by Raman, XAFS, ATR-IR and XRD spectroscopies. The temperature-programmed pulsed flow reaction of methanol showed that this novel, high surface area catalyst (3ML-HSA) outperformed the undoped analogue (3ML-ISA), and a peak yield of 94% formaldehyde was obtained at ?40 °C below that for the bulk Fe2(MoO4)3 phase. This work demonstrates how core-shell, multi-component oxides offer new routes for improving catalytic performance and understanding catalytic activity.

Text
c5fd00153f.pdf - Version of Record
Available under License Other.
Download (851kB)

More information

Accepted/In Press date: 8 December 2015
e-pub ahead of print date: 8 December 2015
Published date: 1 July 2016
Organisations: Organic Chemistry: SCF

Identifiers

Local EPrints ID: 400537
URI: http://eprints.soton.ac.uk/id/eprint/400537
ISSN: 0301-7249
PURE UUID: 1d66b748-e8b4-4249-9dc8-a0f2ab54634c
ORCID for Peter Wells: ORCID iD orcid.org/0000-0002-0859-9172

Catalogue record

Date deposited: 19 Sep 2016 10:31
Last modified: 15 Mar 2024 03:24

Export record

Altmetrics

Contributors

Author: Stephanie Chapman
Author: Catherine Brookes
Author: Michael Bowker
Author: Emma K. Gibson
Author: Peter Wells ORCID iD

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×