A study of stability of tungstophosphoric acid, H{sub 3}PW{sub 12}O{sub 40}, using synchrotron XPS, XANES, Hexane cracking, XRD and IR spectroscopy

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Tungstophosphoric Acid (HPW) has been investigated using different spectroscopic and chemical techniques. Bulk sensitive techniques such as x-ray diffract ion (XRD) and infrared (IR) spectroscopy indicate that the acid is stable at temperatures as high as 300 degrees C or higher. However, our work suggests that HPW starts loosing stability at temperature as low as 200 degrees C. For instance, P 2p peak was not detected in the XPS spectrum of HPW preheated at 100 degrees C, but was clearly observed after preheating the acid at 200 degrees C and 400 degrees C. This suggests the destruction of the molecules ... continued below

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Jalil, Pasl A.; Faiz, M.; Tabet, N.; Hamdan, N.M. & Hussain, Z. June 7, 2002.

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Description

Tungstophosphoric Acid (HPW) has been investigated using different spectroscopic and chemical techniques. Bulk sensitive techniques such as x-ray diffract ion (XRD) and infrared (IR) spectroscopy indicate that the acid is stable at temperatures as high as 300 degrees C or higher. However, our work suggests that HPW starts loosing stability at temperature as low as 200 degrees C. For instance, P 2p peak was not detected in the XPS spectrum of HPW preheated at 100 degrees C, but was clearly observed after preheating the acid at 200 degrees C and 400 degrees C. This suggests the destruction of the molecules of the surface leading to the enrichment of surface with phosphorus. These results may explain why HPW deactivates very fast, e.g., 8 min at 200 degrees C, in hexane cracking experiments. This could limit the use of HPW in surface reactions that even require moderate temperatures. Detailed infrared spectroscopic investigation of the HPW as a function of temperature showed a gradual in crease in absorbance of the W-O-W corner shared vibration relative to the absorbance of the other bands. This indicates that the symmetry, and hence the stability, of the molecule was decreased upon heating.

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  • Journal Name: Journal of Catalysis; Journal Volume: 217; Journal Issue: 2; Other Information: Journal Publication Date: 07/25/2003

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  • Report No.: LBNL--50830
  • Grant Number: AC03-76SF00098
  • Office of Scientific & Technical Information Report Number: 825307
  • Archival Resource Key: ark:/67531/metadc779194

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • June 7, 2002

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  • Dec. 3, 2015, 9:30 a.m.

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  • Sept. 21, 2017, 6:03 p.m.

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Jalil, Pasl A.; Faiz, M.; Tabet, N.; Hamdan, N.M. & Hussain, Z. A study of stability of tungstophosphoric acid, H{sub 3}PW{sub 12}O{sub 40}, using synchrotron XPS, XANES, Hexane cracking, XRD and IR spectroscopy, article, June 7, 2002; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc779194/: accessed December 10, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.