Dow Global Technolgoies LLC

Kevin C Seavey

Carlos M Villa

John W Weston

Jean-Paul Masy

Walter C Moore

Organic materials are stripped and dried in a single column having two contact zones. A stripping gas is introduced into an upper contact zone and flows through the organic material in that zone. A drying gas is introduced into a lower contact zone. The drying gas contacts the organic material in both the upper and lower contact zones, and is removed from the top of the column together with the stripping gas. This process permits very efficiently removal of volatile organic compounds as well as efficient drying, while requiring on low levels of the stripping and drying gasses.

Single column stripping and drying process

Polyether polyols having equivalent weights of up to 500 are continuously prepared in the presence of a double metal cyanide catalyst. A first step of the reaction is performed at a temperature of at least 150&#xb0; C., while controlling the hydroxyl content and unreacted alkylene oxide content of the reaction mixture to within certain ranges. A portion of that reaction mixture is withdrawn and permitted to react non-isothermally to consume the unreacted alkylene oxide. This process is highly efficient, does not result in catalyst deactivation, as is commonly seen in previous processes, and does not produce a significant ultra high molecular weight tail.

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Clute, TX, United States of America

Kevin C Seavey