Inventor · Leverkusen, DE

Friedhelm Steffens

36Patents
6h-index
70Co-inventors
72Inventor score

Filing activity: Oct 2, 1986 → Jun 24, 2020

Most-cited inventions

PatentTitleAreaCited byStatus
US6719957B2 Process for purification of anhydrous hydrogen chloride gas Chemistry; Metallurgy 45 Expired
US7118653B2 Process for the purification of mixtures of toluenediisocyanate incorporating a dividing-wall distillation column Emerging Cross-Sectional Technologies 24 Expired
US9024057B2 Process for the preparation of isocyanates in the gas phase Chemistry; Metallurgy 12 Active
US7541487B2 Process for the preparation of isocyanates in the gas phase Chemistry; Metallurgy 11 Active
US7615662B2 Process for the preparation of isocyanates in the gas phase Chemistry; Metallurgy 10 Active
US8563768B2 Process for the preparation of isocyanates Chemistry; Metallurgy 8 Active
US7645900B2 Process for the preparation of isocyanates Chemistry; Metallurgy 6 Active
US4732685A Method of liquid-liquid extraction using material exchange columns Performing Operations; Transporting 5 Expired
US9480958B2 Device and method for producing phosgene Performing Operations; Transporting 4 Active
US8063241B2 Process for the preparation of toluene-diisocyanate Chemistry; Metallurgy 4 Active
US9932299B2 Process for separating an isocyanate prepared by phosgenation of a primary amine in the gas phase from the gaseous crude product of the phosgenation Chemistry; Metallurgy 2 Active
US8399702B2 Process for the production of aromatic diisocyanates in the gas Chemistry; Metallurgy 2 Active
US7322565B2 Stirring device and process for carrying out a gas-liquid reaction Performing Operations; Transporting 2 Expired
US7511176B2 Process for the preparation of toluenediamines by catalytic hydrogenation of dinitrotoluenes Chemistry; Metallurgy 2 Active
US8030522B2 Process for the production of toluene diisocyanate Chemistry; Metallurgy 2 Active
US9029595B1 Method for working up distillation residues from isocyanate production Chemistry; Metallurgy 1 Active
US7575660B2 Process for the distillative separation of aqueous amine solutions Emerging Cross-Sectional Technologies 1 Active
US9840461B2 Method for operating a gas-phase phosgenation plant Chemistry; Metallurgy 1 Active
US9376377B2 Method for producing isocyanates Chemistry; Metallurgy 1 Active
US9365503B2 Process for the preparation of isocyanates in the gas phase Chemistry; Metallurgy 1 Active
US10435353B2 Method for producing isocyanates Chemistry; Metallurgy 0 Active
US11267703B2 Method and a system for separating and treating impurities from a hydrogen chloride liquid mixture Chemistry; Metallurgy 0 Active
US9938147B2 Process for purifying raw-material gases by fractionation Chemistry; Metallurgy 0 Active
US9845286B2 Process for operating a gas phase phosgenation plant Performing Operations; Transporting 0 Active
US10576392B2 Distillation column and use thereof for cleaning isocyanates Chemistry; Metallurgy 0 Active

Source: USPTO / EPO open patent data. Inventor disambiguation is heuristic; counts are objective bibliographic measures.