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In situ spectroscopic investigations of MoOx/Fe2O3 catalysts for the selective oxidation of methanol

DOI: 10.1039/C5CY01175B DOI Help

Authors: Catherine Brookes (University of Cardiff) , Peter Wells (University College London) , Emma Gibson (University College London) , Diego Gianolio (Diamond Light Source) , Khaled Mohammed (University College London (UCL)) , Stephen Parry (Diamond Light Source) , Scott Rogers (Rutherford Appleton Laboratory; University College London (UCL)) , Ian Silverwood (University College London (UCL)) , Michael Bowker (University of Cardiff)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Catalysis Science & Technology

State: Published (Approved)
Published: August 2015
Diamond Proposal Number(s): 8071

Open Access Open Access

Abstract: Multicomponent oxide shell@core catalysts have been prepared, affording overlayers of MoOx on Fe2O3. This design approach allows bulk characterization techniques, such as X-ray Absorption Fine Structure (XAFS), to provide surface sensitive information. Coupling this approach with in situ methodologies provides insights during crucial catalytic processes. Calcination studies were followed by a combination of XAFS and Raman, and demonstrate that amorphous multi-layers of MoOx are first converted to MoO3 before formation of Fe2(MoO4)3. However, a single overlayer of Oh Mo units remains at the surface at all times. In situ catalysis studies during formaldehyde production identified that Mo6+ was present throughout, confirming that gas phase oxygen transfer to molybdenum is rapid under reaction conditions. Reduction studies in the presence of MeOH resulted in the formation of reduced Mo-Mo clusters with a bonding distance of 2.6 Å. It is proposed that the presence of the clusters indicates that the selective conversion of MeOH to formaldehyde requires multiple Mo sites.

Subject Areas: Chemistry

Instruments: B18-Core EXAFS