Granted Patent B2

US 12,606,507 · App. 18/249,825 · Granted Apr 21, 2026

Inventors: Holger Wiederhold (Darmstadt, DE); David Bolz (Frankfurt, DE); Jürgen Glenneberg (Offenbach, DE)

Assignee: Evonik Operations GmbH

C07C29/48B01D3/143B01J23/42B01J31/0255C07C29/80

Abstract

Claims (24)

1 . A method for the preparation of 1,2-propanediol, comprising:

a) reacting propene with hydrogen peroxide in the presence of a catalyst mixture comprising a phase transfer catalyst, phosphoric acid, and a heteropolytungstate, in a liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6 and an organic phase, wherein apparent pH refers to a value determined by measurement with a glass electrode employing a commercial pH meter calibrated with aqueous buffer solutions of known pH for measuring dilute aqueous solutions;

b) separating the liquid reaction mixture into an aqueous phase (P a ) comprising 1,2-propanediol and formic acid, and an organic phase (P o );

c) recycling at least a part of the organic phase (P o ) to a);

d) contacting at least a part of the aqueous phase (P a ) separated in b) with a palladium catalyst to provide a treated aqueous phase, wherein no hydrogen is added in d); and

e) recovering the 1,2-propanediol from the treated aqueous phase provided in d).

2 . The method of claim 1 , wherein the contacting in d) is conducted at a pressure sufficient to maintain a liquid aqueous phase.

3 . The method of claim 2 , wherein the pressure in d) is from 1 to 100 bar.

4 . The method of claim 1 , wherein a temperature in d) is between 0° C. and 200° C.

5 . The method of claim 1 , wherein between b) and d) or between d) and e), at least a part of the aqueous phase (P a ) is subjected to a catalytic hydrogenation at a temperature in the range of 80° C. to 140° C.

6 . The method of claim 1 , wherein e) comprises a multi-step distillation, with a first distillation step and optionally further distillation steps providing an overhead product comprising water and a bottoms product which is passed to a next distillation step, and a subsequent distillation step providing an overhead product comprising the 1,2-propanediol and a residuals bottoms product.

7 . The method of claim 6 , wherein the residuals bottoms product is subjected to at least one further distillation step.

8 . The method of claim 1 , wherein phosphoric acid is present in a), and wherein the heteropolytungstate is a polytungstophosphate.

9 . The method of claim 1 , wherein the organic phase in a) comprises an organic solvent having a boiling point of more than 100° C. at atmospheric pressure and a solubility in water at 20° C. of less than 250 mg/kg.

10 . The method of claim 1 , wherein the phase transfer catalyst comprises at least one selected from the group consisting of a tertiary amine, a tertiary ammonium salt, and a quaternary ammonium salt, and

wherein the tertiary amine, the tertiary ammonium salt, and the quaternary ammonium salt each comprises in total at least 12 carbon atoms.

11 . The method of claim 10 , wherein the phase transfer catalyst comprises a tertiary or quaternary ammonium ion having the structure R 1 R 2 R 3 NR 4+ ,

wherein

R 1 , R 2 , and R 3 are the same or different and are cach an alkyl group having from 8 to 10 carbon atoms, and

R 4 is hydrogen or methyl.

12 . The method of claim 11 , wherein in d), the formic acid is decomposed.

13 . The method of claim 4 , wherein the temperature in d) is in the range of 100° C. to 180° C.

14 . The method of claim 5 , wherein the catalytic hydrogenation is at a temperature in the range of 90° C. to 120° C.

15 . The method of claim 9 , wherein the organic solvent is an alkylated aromatic hydrocarbon having 8 to 12 carbon atoms.

Priority Claims (1)

Continuity (1)

References Cited (23)