Patents by Inventor Steven Charles Zronek

Steven Charles Zronek has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Purification of 1,3-propanediol in carbonyl-containing stream
    Patent number: 6245879
    Abstract: A process for preparing polytrimethylene terephthalate in which a carbonyl-containing 1,3-propanediol stream is purified for reuse of the 1,3-propanediol. The process involves reacting, under condensation polymerization conditions, terephthalic acid and a molar excess of 1,3-propanediol, with vacuum distillation and condensation of a major portion of the unreacted 1,3-propanediol. To this condensed stream is added a sufficient amount of base to raise the pH to a value greater than 7, and from this base-containing condensate the 1,3-propanediol is distilled and recycled to the polymerization reaction.
    Type: Grant
    Filed: January 29, 1999
    Date of Patent: June 12, 2001
    Assignee: Shell Oil Company
    Inventors: Donald Ross Kelsey, Betty Marrou Scardino, Steven Charles Zronek