Patents by Inventor Stefan Frentzen

Stefan Frentzen 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).

  • Patent number: 5773622
    Abstract: A process for the continuous preparation of 4-amino-2,2,6,6-tetramethylpiperidine (TAD), comprising: passing triacetoneamine, ammonia and hydrogen over a catalyst of at least two layers in a reactor, wherein at least one catalyst layer comprises at least one element of the 4th, 5th, or 6th row of the 8th transition group of the Periodic Table or combinations of these metal elements on a suitable support, where the catalyst content with respect to each individual catalytically active element changes independently from the reactor inlet to the reactor outlet.
    Type: Grant
    Filed: December 2, 1996
    Date of Patent: June 30, 1998
    Assignee: Huels Aktiengesellschaft
    Inventors: Udo Jegelka, Gerhard Bachstaedter, Stefan Frentzen, Guenter Kreilkamp, Gerhard Thelen
  • Patent number: 5693817
    Abstract: A process for preparing 4-amino 2,2,6,6-tetramethylpiperidine (TAD) from 2,2,6,6-tetramethylpiperidone (TAA), ammonia and hydrogen using a cobalt or nickel catalyst on a support which allows the omission of any added solvent, and provides substantially simplified work-up and increased space-time yields by significantly reducing the amounts of excess ammonia and catalyst needed to accomplish the reaction.
    Type: Grant
    Filed: December 4, 1995
    Date of Patent: December 2, 1997
    Assignee: Huels Aktiengesellschaft
    Inventors: Stefan Frentzen, Elmhart Neuber, Gerhard Thelen