Granted Patent
Utility
US 4,663,028 · App. 06/770,082
Process of preparing a donor solvent for coal liquefaction
Inventor:
John G. Ditman
Patented Case
View Patent ↗
Granted: May 5, 1987
Filed: Aug 28, 1985
Inventor
John G. Ditman
Assignee (at issue)
Foster Wheeler USA Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.