Erco Industries Limited

Tenneco Canada Inc.

Helena Twardowska

James D McGilvery

Slawomir M Cybulski

Phosphorous acid is formed by gaseous phase oxidation of phosphorus with water vapour to form predominantly P.sub.2 O.sub.3 and dissolving the P.sub.2 O.sub.3 so-formed in water. The P.sub.2 O.sub.3 also can be recovered as the product by quenching the P.sub.2 O.sub.3 to a stable temperature using an inert cooling medium rather than water. Oxygen also may be used in conjunction with the water vapour. Sufficiently rapid quenching of reaction products may result in the formation of red amorphous phosphorus from unreacted phosphorus.

Preparation of phosphorous acid

Particulate red amorphous phosphorus is stabilized against oxidation and phosphine formation by the use of a combination of titanium dioxide or titanium phosphate and an organic resin, usually an epoxy resin, a melamine-formaldehyde resin or a urea-formaldehyde resin.

Stabilization of red phosphorus

Particulate red amorphous phosphorus is stabilized against oxidative degradation to phosphorus acids and phosphine by the use of titanium dioxide or titanium phosphate.

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Mississauga, Canada

Helena Twardowska