The CsxH3 - XPW12O40 catalysts microstructure model

V. Z. Sasca, O. Verdes, L. Avram, A. Popa, A. Erdohelyi, A. Oszko

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The salts of the H3PW12O40 (H 3PW) with Cs counter cation were prepared and characterized by thermal analysis, IR, XRD, BET, XPS LEIS and SEM methods. The samples are denoted as CsxH3 - xPW12O40 (x = 1, 2, 2.25, 2.5 and 3). The catalytic activity of the compounds prepared with various cesium/Keggin unit ratios was tested in ethanol conversion by pulse reaction technique. The change of catalytic activity vs. pulse number was explained by formation of strong adsorbed species on catalysts. A microstructure model of the CsxH3 - xPW12O40 containing spherical aggregates, which consist of Cs3PW 12O40 crystallites core coated with H3PW 12O40 layers, was proposed on the basis of the structural-textural properties and their catalytic performances in ethanol conversion. The model explains the abrupt increase of the specific surface area for x > 2 and also the highest selectivity for C4 hydrocarbons on Cs2.5H0.5PW12O40 due to its special microstructure: a H3PW monolayer embedding a core of Cs 3PW. The Cs concentrations on the CsxH 3 - xPW12O40 surface were determined by XPS and were found less than expected based on their chemical composition, but which correspond to the proposed model of microstructure.

Original languageEnglish
Pages (from-to)50-57
Number of pages8
JournalApplied Catalysis A: General
Volume451
DOIs
Publication statusPublished - Jan 31 2013

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Keywords

  • Cesium tungstophosphates
  • Ethanol conversion
  • Heteropoly compounds
  • Keggin structure
  • Microstructure model
  • XPS measurements

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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