Stability and performance of cation vacant Fe3-x-yVx□yO4 spinel phase catalysts in methanol oxidation

Research output: Contribution to journalArticle

Standard

Stability and performance of cation vacant Fe3-x-yVx□yO4 spinel phase catalysts in methanol oxidation. / Häggblad, Robert; Hansen, Staffan; Wallenberg, Reine; Andersson, Arne.

In: Journal of Catalysis, Vol. 276, No. 1, 2010, p. 24-37.

Research output: Contribution to journalArticle

Harvard

APA

CBE

MLA

Vancouver

Author

RIS

TY - JOUR

T1 - Stability and performance of cation vacant Fe3-x-yVx□yO4 spinel phase catalysts in methanol oxidation

AU - Häggblad, Robert

AU - Hansen, Staffan

AU - Wallenberg, Reine

AU - Andersson, Arne

N1 - The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Engineering (011001014), Polymer and Materials Chemistry (LTH) (011001041)

PY - 2010

Y1 - 2010

N2 - A series of spinel type Fe-V-O phases were prepared with V/Fe atomic ratios ranging from 0 to 1 and were used for methanol oxidation to formaldehyde. X-ray powder diffraction shows that the basic spinel-type structure is retained after use of the samples in methanol oxidation. Compared with the freshly prepared samples, in and ex situ analyses of the samples with XANES show that both V and Fe are oxidized under influence of methanol oxidation, where octahedrally coordinated V3+ partially is oxidized to V4+. Simultaneously, partial oxidation occurs of Fe2+ in tretrahedral and octahedral coordinations to form Fe3+ species. XPS reveals that in general the surfaces with predominantly V5+ and Fe3+ species are more oxidized compared to the bulk. Besides XRD, HRTEM imaging confirms that the basic rutile-type structure is stable in methanol oxidation. Consequently, the structure is very flexible allowing the cations to change oxidation state by forming cation vacancies without structural breakdown. All preparations show activity of similar magnitude although great differences in selectivity to formaldehyde. The best performing spinel catalyst is poor in vanadium with a V/Fe ratio of 1/14, indicating that isolated vanadia moieties perform better than polymeric vanadia structures. The stable and flexible structure makes the spinel-type Fe-V-O catalysts an interesting alternative to the presently used industrial catalyst consisting of a mixture of MoO3 and ferric molybdate. Opposed to the industrial catalyst, which suffers from Mo volatilization, the spinel samples show no measurable volatilization of vanadium.

AB - A series of spinel type Fe-V-O phases were prepared with V/Fe atomic ratios ranging from 0 to 1 and were used for methanol oxidation to formaldehyde. X-ray powder diffraction shows that the basic spinel-type structure is retained after use of the samples in methanol oxidation. Compared with the freshly prepared samples, in and ex situ analyses of the samples with XANES show that both V and Fe are oxidized under influence of methanol oxidation, where octahedrally coordinated V3+ partially is oxidized to V4+. Simultaneously, partial oxidation occurs of Fe2+ in tretrahedral and octahedral coordinations to form Fe3+ species. XPS reveals that in general the surfaces with predominantly V5+ and Fe3+ species are more oxidized compared to the bulk. Besides XRD, HRTEM imaging confirms that the basic rutile-type structure is stable in methanol oxidation. Consequently, the structure is very flexible allowing the cations to change oxidation state by forming cation vacancies without structural breakdown. All preparations show activity of similar magnitude although great differences in selectivity to formaldehyde. The best performing spinel catalyst is poor in vanadium with a V/Fe ratio of 1/14, indicating that isolated vanadia moieties perform better than polymeric vanadia structures. The stable and flexible structure makes the spinel-type Fe-V-O catalysts an interesting alternative to the presently used industrial catalyst consisting of a mixture of MoO3 and ferric molybdate. Opposed to the industrial catalyst, which suffers from Mo volatilization, the spinel samples show no measurable volatilization of vanadium.

KW - Fe3-x-yVx□yO4 catalysts

KW - Fe-V-O spinel-type phases

KW - Volatility

KW - in situ XANES

KW - XRD

KW - XPS

KW - HRTEM

KW - TPO

KW - Formaldehyde

KW - Selective oxidation

KW - Methanol

U2 - 10.1016/j.jcat.2010.08.012

DO - 10.1016/j.jcat.2010.08.012

M3 - Article

VL - 276

SP - 24

EP - 37

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 1090-2694

IS - 1

ER -