A method for the preparation of 1,2-propanediol, dipropylene glycol and tripropylene glycol

• Main Authors: GLENNEBERG, JUERGEN, BOLZ, DAVID, WIEDERHOLD, HOLGER
• Format: Patent
• Language: Chinese; English
• Published: 01.09.2022
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY

The method for preparing 1,2-propanediol, dipropylene glycol and tripropylene glycol comprises step (a) of reacting propene with hydrogen peroxide containing nitrate in the presence of a catalyst mixture comprising a phase transfer catalyst and a heteropolytungstate in a liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6 and an organic phase; step (b) of separating the reaction mixture into an aqueous phase comprising 1,2-propanediol, dipropylene glycol, tripropylene glycol and nitrate and an organic phase; step (c) of recycling at least part of the separated organic phase to the reaction step (a); step (d) of hydrogenating the separated aqueous phase using a heterogeneous hydrogenation catalyst to provide a hydrogenated aqueous phase with a reduced nitrate content; and step (e) of recovering 1,2-propanediol, dipropylene glycol and tripropylene glycol from the hydrogenated aqueous phase by a sequential multiple step distillation.