English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Surface chemistry of phase-pure M1 MoVTeNb oxide during operation in selective oxidation of propane to acrylic acid

Hävecker, M., Wrabetz, S., Kröhnert, J., Csepei, L.-I., Naumann d'Alnoncourt, R., Kolen’ko, Y. V., et al. (2012). Surface chemistry of phase-pure M1 MoVTeNb oxide during operation in selective oxidation of propane to acrylic acid. Journal of Catalysis, 285, 48-60. doi:10.1016/j.jcat.2011.09.012.

Item is

Files

show Files
hide Files
:
1108560.pdf (Any fulltext), 2MB
Name:
1108560.pdf
Description:
-
OA-Status:
Visibility:
Public
MIME-Type / Checksum:
application/pdf / [MD5]
Technical Metadata:
Copyright Date:
2012
Copyright Info:
Elsevier
License:
-
:
1108560 CTA.pdf (Copyright transfer agreement), 112KB
 
File Permalink:
-
Name:
1108560 CTA.pdf
Description:
-
OA-Status:
Visibility:
Private
MIME-Type / Checksum:
application/pdf
Technical Metadata:
Copyright Date:
-
Copyright Info:
-
License:
-
:
1108560.pdf (Correspondence), 84KB
 
File Permalink:
-
Name:
1108560.pdf
Description:
-
OA-Status:
Visibility:
Private
MIME-Type / Checksum:
application/pdf
Technical Metadata:
Copyright Date:
-
Copyright Info:
-
License:
-

Locators

show

Creators

show
hide
 Creators:
Hävecker, Michael1, Author           
Wrabetz, Sabine1, Author           
Kröhnert, Jutta1, Author           
Csepei, Lenard-Istvan1, Author           
Naumann d'Alnoncourt, Raoul1, Author           
Kolen’ko, Yuri V.1, Author           
Girgsdies, Frank1, Author           
Schlögl, Robert1, Author           
Trunschke, Annette1, Author           
Affiliations:
1Inorganic Chemistry, Fritz Haber Institute, Max Planck Society, ou_24023              

Content

show
hide
Free keywords: MoVTeNb oxide; M1 phase; Propane oxidation; Acrylic acid; Adsorption; Microcalorimetry; In situ XPS; Operando; Active sites
 Abstract: The surface of a highly crystalline MoVTeNb oxide catalyst for selective oxidation of propane to acrylic acid composed of the M1 phase has been studied by infrared spectroscopy, microcalorimetry, and in situ photoelectron spectroscopy. The acid–base properties of the catalyst have been probed by NH3 adsorption showing mainly Brønsted acidity that is weak with respect to concentration and strength of sites. Adsorption of propane on the activated catalyst reveals the presence of a high number of energetically homogeneous propane adsorption sites, which is evidenced by constant differential heat of propane adsorption qdiff,initial = 57 kJ mol−1 until the monolayer coverage is reached that corresponds to a surface density of approximately 3 propane molecules per nm2 at 313 K. The decrease of the heat to qdiff,initial = 40 kJ mol−1 after catalysis implies that the surface is restructured under reaction conditions. The changes have been analyzed with high-pressure in situ XPS while the catalyst was working applying reaction temperatures between 323 and 693 K, different feed compositions containing 0 mol.% and 40 mol.% steam and prolonged reaction times. The catalytic performance during the XPS experiments measured by mass spectrometry is in good agreement with studies in fixed-bed reactors at atmospheric pressure demonstrating that the XPS results taken under operation show the relevant active surface state. The experiments confirm that the surface composition of the M1 phase differs significantly from the bulk implying that the catalytically active sites are no part of the M1 crystal structure and occur on all terminating planes. Acrylic acid formation correlates with surface depletion in Mo6+ and enrichment in V5+ sites. In the presence of steam in the feed, the active ensemble for acrylic acid formation appears to consist of V5+ oxo-species in close vicinity to Te4+ sites in a Te/V ratio of 1.4. The active sites are formed under propane oxidation conditions and are embedded in a thin layer enriched in V, Te, and Nb on the surface of the structural stable self-supporting M1 phase.

Details

show
hide
Language(s): eng - English
 Dates: 2011-09-122011-10-182012-01
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1016/j.jcat.2011.09.012
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Journal of Catalysis
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: San Diego, CA. : Academic Press
Pages: - Volume / Issue: 285 Sequence Number: - Start / End Page: 48 - 60 Identifier: ISSN: 0021-9517
CoNE: https://pure.mpg.de/cone/journals/resource/954922645027