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In-Situ Dynamic Transformation of Vanadyl Hydrogen Phosphate Hydrate, VOHPO4·1/2H2O, to Vanadyl Pyrophosphate Catalyst, (VO)2P2O7

Published online by Cambridge University Press:  15 February 2011

P. L. Gai  and
C. C. Torardi
P. L. Gai
Affiliation:
Central Research & Development, DuPont Science and Engineering Laboratories, Experimental Station, Wilmington, Delaware 19880–0356.
C. C. Torardi
Affiliation:
Central Research & Development, DuPont Science and Engineering Laboratories, Experimental Station, Wilmington, Delaware 19880–0356.
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Abstract

We report, for the first time, direct studies of the dynamic VOHPO4·1/2H2O precursor to (VO)2P2O7 catalyst transformation using recently developed in-situ environmental-cell, high-resolution, electron microscopy (in-situ ECELL-HREM) under controlled environments. Our observations provide fundamental evidence concerning the nature of the topotactic transformation and associated temperature regimes critical to the formation of active catalysts. The direct ECELL-HREM studies show that the structural transformation begins at ˜ 400°C, and a mixture of the precursor and pyrophosphate phases exists at ˜ 425°C. At 450°C, most of the conversion to VPO has taken place. These atomic-scale studies reveal no amorphous phases during the transformation, and that the atomic periodicity is maintained throughout. No other phases have so far been identified in the transformation. The direct studies are important in the development of selective catalysts.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 404: Symposium J – In Situ Electron and Tunneling Microscopy of Dynamic Processes , 1995 , 61
Copyright
Copyright © Materials Research Society 1996

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