Patents by Inventor David John Royall

David John Royall 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).

  • Production of terephthalic acid
    Patent number: 6307099
    Abstract: An aromatic carboxylic acid such as terephthalic acid is produced by the liquid phase oxidation of a precursor thereof, the oxidation being carried out in such a way that substantially all of the aromatic carboxylic acid produced in the course of the reaction is maintained in solution during the reaction.
    Type: Grant
    Filed: January 7, 2000
    Date of Patent: October 23, 2001
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: John Arthur Turner, David John Royall, Duncan Stuart Hugall, Graham Howard Jones, Duncan Charles Woodcock
  • Production of aromatic carboxylic acids and recovery of Co/Mn catalyst from ash
    Patent number: 6255510
    Abstract: Cobalt and/or manganese is recovered from the ash obtained following incineration of the catalyst containing residue arising from the liquid phase oxidation of an aromatic carboxylic acid such as terephthalic acid. Recovery is effected by contacting the ash with an organic acid or an organic acid anhydride such as acetic anhydride, optionally in the presence of bromide ions (e.g. HBr), so that the cobalt and/or manganese metals are recovered as monocarboxylic acid soluble salts thereof thus permitting recycle thereof to the liquid phase oxidation process.
    Type: Grant
    Filed: March 24, 2000
    Date of Patent: July 3, 2001
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: David John Royall, Julie Ann Bartlett, Roger Gaskell Fairhurst