Process for preparing 1,2-propanediol from propane

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).