The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 23, 2002
Filed:
Aug. 25, 1999
James P. Cosman, Sarnia, CA;
Paul D. Bettge, Lake Jackson, TX (US);
Richard J. Elwell, Terneuzen, NL;
Raymond A. Plepys, Lake Jackson, TX (US);
The Dow Chemical Company, Midland, MI (US);
Abstract
This invention involves several ways for improving a coalescing process for purifying a crude polyether. In one aspect, particulate zirconium dioxide is selected as a coalescing medium. In a second aspect, alkali metal catalyst is recovered and recycled to make additional polyether product. In a third aspect, a polyether stream obtained from the coalescing step is purified by stripping water in at least two phases, the first of which involves moderate conditions so that water but not allyl alcohol or higher molecular weight impurities are removed from the polyether, and the second of which involves more stringent stripping conditions. In a fourth aspect, crude polyether that is subjected to a holding period before undergoing a coalescing step is mixed with water to minimize the formation of impurities that are believed to compatibilize the aqueous and polyether phases. In a fifth aspect, the coalescing process is conducted under a non-oxidizing atmosphere.