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Proceedings Paper

Kinetic studies of phosgene reduction via in situ Fourier transform infrared analysis
Author(s): Stuart Farquharson; J. Paul Chauvel Jr.
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Paper Abstract

Phosgene, a common reactant in the production of polyurethanes and polycarbonates, is unfortunately hazardous (threshold limit value equals 0.1 ppm). Consequently, the detection and elimination of atmospheric releases are paramount safety and environmental concerns. Proper design of systems to mitigate phosgene requires knowledge of the reaction kinetics for the chemistry involved. This paper presents our investigation of the reactions for phosgene with steam and ammonia. A Fourier transform infrared spectrometer (FTIR) equipped with a large volume (15 L), temperature controlled (+0.5 degree(s)C), 24.5 cm path length cell was used to measure the reaction kinetics. The reaction of phosgene with steam at 110 degree(s)C followed first order kinetics (t1/2 equals 10.2 min.) producing carbon dioxide and hydrogen chloride. The reaction of phosgene with ammonia at 80 degree(s)C followed second order kinetics (t1/2 equals 1.2 min.) producing ammonium chloride and urea. It was found, however, that at 25 degree(s)C this reaction follows a previously unreported pathway producing ammonium chloride and ammonium isocyanate at a faster rate (t1/2 equals 15 sec.). Based on this reaction, a pilot scale scrubbing tower was built with a manifold to mix ammonia with ppm levels of phosgene. A complete description of the experimental conditions, the reaction pathways as a function of temperature, and the performance of the ammonia scrubbing tower are given.

Paper Details

Date Published: 1 April 1991
PDF: 12 pages
Proc. SPIE 1434, Environmental Sensing and Combustion Diagnostics, (1 April 1991); doi: 10.1117/12.48468
Show Author Affiliations
Stuart Farquharson, Dow Chemical Co. (United States)
J. Paul Chauvel Jr., Dow Chemical Co. (United States)

Published in SPIE Proceedings Vol. 1434:
Environmental Sensing and Combustion Diagnostics
Joseph J. Santoleri, Editor(s)

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