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Title: Transformation of Mo and W thiosalts into unsupported sulfide catalysts: A temperature dependent in-situ spectroscopic investigation

Highlights: • TPD–MS results suggest that the majority of S remains in the solid sample after decomposition. • Decomposition of the (CH{sub 3}){sub 4}N is not directly correlated with that of the MS{sub 4}{sup 2−} species. • Surface of materials does not track directly with the bulk at various treatment temperatures. • ATT-derived materials retained a significant amount of +6 state consistent with the precursor. - Abstract: The thermal decomposition of ammonium thiomolybdate (ATM), ammonium thiotungstate (ATT), tetramethylammonium thiomolybdate (TMATM) and tetramethylammonium thiotungstate (TMATT) are investigated as a function of temperature by using thermogravimetric analysis (TGA), temperature-programmed decomposition with mass spectroscopy (TPS–MS), in-situ Fourier transform infrared (FTIR) and Raman spectroscopies, and X-ray photoelectron spectroscopy (XPS). The results allow for correlations to be made between the changes in the bulk and surface structures of the materials, and the evolution of gas-phase decomposition products. The major difference between the ammonium and tetramethylammonium precursors is the complexity of the thermal decomposition profile, which is found to follow two steps over a wide temperature range for the former, but one step over a relatively narrow range for the latter materials. Raman and FTIR spectra reveal the decomposition of the ammonium and tetramethylammonium groups, alongmore » with the decomposition of the initial sulfide structures to metal disulfides. For both sets of precursors, XPS results show that the surface of the resulting materials at various temperatures of treatment does not track directly with the state of the bulk material. While the ATM, TMATM, and TMATT-derived material surfaces are reduced to the 4{sup +} state at the highest temperature, indicating disulfides, the ATT-derived materials still retained a significant amount of W{sup 6+} state consistent with the starting precursor.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [3] ;  [1]
  1. Laboratory of Advanced Materials and Catalytic Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)
  2. (United States)
  3. Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)
Publication Date:
OSTI Identifier:
22420528
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 56; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMMONIUM COMPOUNDS; CATALYSTS; FOURIER TRANSFORMATION; INFRARED SPECTRA; MASS SPECTROSCOPY; MOLYBDATES; ORGANIC SULFUR COMPOUNDS; PYROLYSIS; RAMAN SPECTROSCOPY; SOLIDS; SURFACES; TEMPERATURE DEPENDENCE; THERMAL GRAVIMETRIC ANALYSIS; TUNGSTATES; TUNGSTEN IONS; X-RAY PHOTOELECTRON SPECTROSCOPY