US 12,459,882 B2
Process for preparing 1,2-propanediol from propane
David Bolz, Frankfurt (DE); and Holger Wiederhold, Darmstadt (DE)
Assigned to Evonik Operations GmbH, Essen (DE)
Appl. No. 18/249,729
Filed by Evonik Operations GmbH, Essen (DE)
PCT Filed Oct. 7, 2021, PCT No. PCT/EP2021/077652
§ 371(c)(1), (2) Date Apr. 19, 2023,
PCT Pub. No. WO2022/084048, PCT Pub. Date Apr. 28, 2022.
Claims priority of application No. 20203009 (EP), filed on Oct. 21, 2020.
Prior Publication US 2023/0382835 A1, Nov. 30, 2023
Int. Cl. C07C 29/50 (2006.01); C07C 29/84 (2006.01)
CPC C07C 29/50 (2013.01) [C07C 29/84 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A process for preparing 1,2-propanediol, comprising:
a) dehydrogenating a feed stream SI comprising propane, to provide a product stream S2 comprising propane, propene and hydrogen;
b) separating product stream S2 into a stream S3 consisting essentially of the hydrogen and a stream S4 comprising the propane and the propene with a combined amount of the propane and the propene of at least 95% by weight;
c) reacting all or a part of stream S3 with oxygen, to provide a stream S5 comprising hydrogen peroxide;
d) separating stream S4 into a stream S6 enriched in the propane and a stream S7 enriched in the propene;
e) reacting all or a part of stream S7 with stream S5 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, wherein apparent pH refers to a value determined by measurement with a glass electrode employing a commercial pH meter calibrated with aqueous buffer solution of known pH for measuring dilute aqueous solutions;
f) separating the liquid reaction mixture of e) into an aqueous phase (Pa) comprising 1,2-propanediol and an organic phase (Po);
g) recycling the organic phase (Po) separated in f) to the reaction of e); and
h) separating the 1,2-propanediol from the aqueous phase (Pa) separated in f).