Patents by Inventor Donald L. Pferdehirt

Donald L. Pferdehirt 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: 7504533
    Abstract: Isocyanates are produced by a) reacting at least one amine with phosgene, optionally in the presence of a solvent to produce the corresponding isocyanate and a stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances is obtained, b) separating the stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances in an at least two-stage sequence of absorption steps that includes (1) at least one isothermal absorption step and (2) at least one adiabatic absorption step, to obtain (i) a hydrogen chloride stream containing phosgene in concentrations of at most 0.5 wt. % (based on the weight of the hydrogen chloride stream) and (ii) a liquid phosgene stream, and c) recycling the liquid phosgene stream (ii) to the reaction of amine with phosgene.
    Type: Grant
    Filed: April 24, 2006
    Date of Patent: March 17, 2009
    Assignees: Bayer MaterialScience LLC, Bayer MaterialScience AG
    Inventors: Matthias Böhm, Wolfgang Lorenz, Bill L. Brady, Jr., Donald L. Pferdehirt