Oxidation of methanol to formaldehyde on cation vacant Fe-V-Mo-oxide

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Oxidation of methanol to formaldehyde on cation vacant Fe-V-Mo-oxide. / Massa, Mariano; Häggblad, Robert; Hansen, Staffan; Andersson, Arne.

In: Applied Catalysis A: General, Vol. 408, No. 1-2, 2011, p. 63-72.

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Massa, Mariano ; Häggblad, Robert ; Hansen, Staffan ; Andersson, Arne. / Oxidation of methanol to formaldehyde on cation vacant Fe-V-Mo-oxide. In: Applied Catalysis A: General. 2011 ; Vol. 408, No. 1-2. pp. 63-72.

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TY - JOUR

T1 - Oxidation of methanol to formaldehyde on cation vacant Fe-V-Mo-oxide

AU - Massa, Mariano

AU - Häggblad, Robert

AU - Hansen, Staffan

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: Polymer and Materials Chemistry (LTH) (011001041), Chemical Engineering (011001014)

PY - 2011

Y1 - 2011

N2 - A spinel-type catalyst of the composition Fe(2.50(1-z/3))V(0.20(1-z/3))Mo(0.30(1-z/3))square(z)O(4), where z is the number of cation vacancies (El), was prepared under reducing atmosphere. From the reduced sample a number of preoxidized samples were made by TPO treatment of the reduced material to different end temperatures ranging from 150 to 450 degrees C. XRD shows that the spinel-type structure is maintained irrespective of the degree of preoxidation of the sample and the related increasing number of cation vacancies. The number of cation vacancies z increases from 0.12 for the most reduced sample up to 0.62 for the most oxidized sample. XANES data reveals that in the most reduced sample the cations are essentially Fe(2+),Fe(3+), V(3+), Mo(4+) and Mo(5+) in the bulk, whereas the most oxidized sample has Fe(3+), V(4+) and Mo(6+). XPS analysis shows that at the surface the metals are mainly in their highest oxidation state, i.e. Fe(3+),V(5+) and Me(6+). Irrespective of the degree of preoxidation of the catalyst, the same catalytic performance and composition of both the surface and the bulk are approached when the samples are used in methanol oxidation. Both the activity and the selectivity to formaldehyde increase initially with time-on-stream, and in parallel there is some enrichment of vanadium and molybdenum taking place at the surface. At steady state conditions the spinel-type catalyst gives a selectivity to formaldehyde of about 86% at high methanol conversion. Our results demonstrate that the spinel-type structure is flexible and stable at both reducing and oxidizing conditions, allowing the cations to change valence while maintaining the same basic structure type. Moreover, the spinel-type catalyst is stable towards volatilization. (C) 2011 Elsevier B.V. All rights reserved.

AB - A spinel-type catalyst of the composition Fe(2.50(1-z/3))V(0.20(1-z/3))Mo(0.30(1-z/3))square(z)O(4), where z is the number of cation vacancies (El), was prepared under reducing atmosphere. From the reduced sample a number of preoxidized samples were made by TPO treatment of the reduced material to different end temperatures ranging from 150 to 450 degrees C. XRD shows that the spinel-type structure is maintained irrespective of the degree of preoxidation of the sample and the related increasing number of cation vacancies. The number of cation vacancies z increases from 0.12 for the most reduced sample up to 0.62 for the most oxidized sample. XANES data reveals that in the most reduced sample the cations are essentially Fe(2+),Fe(3+), V(3+), Mo(4+) and Mo(5+) in the bulk, whereas the most oxidized sample has Fe(3+), V(4+) and Mo(6+). XPS analysis shows that at the surface the metals are mainly in their highest oxidation state, i.e. Fe(3+),V(5+) and Me(6+). Irrespective of the degree of preoxidation of the catalyst, the same catalytic performance and composition of both the surface and the bulk are approached when the samples are used in methanol oxidation. Both the activity and the selectivity to formaldehyde increase initially with time-on-stream, and in parallel there is some enrichment of vanadium and molybdenum taking place at the surface. At steady state conditions the spinel-type catalyst gives a selectivity to formaldehyde of about 86% at high methanol conversion. Our results demonstrate that the spinel-type structure is flexible and stable at both reducing and oxidizing conditions, allowing the cations to change valence while maintaining the same basic structure type. Moreover, the spinel-type catalyst is stable towards volatilization. (C) 2011 Elsevier B.V. All rights reserved.

KW - Fe-V-Mo-oxide

KW - Spinel-type catalyst

KW - Cation vacancies

KW - XRD

KW - XANES

KW - XPS

KW - Methanol oxidation

KW - Formaldehyde

U2 - 10.1016/j.apcata.2011.09.015

DO - 10.1016/j.apcata.2011.09.015

M3 - Article

VL - 408

SP - 63

EP - 72

JO - Applied Catalysis A: General

T2 - Applied Catalysis A: General

JF - Applied Catalysis A: General

SN - 0926-860X

IS - 1-2

ER -