Process for the simultaneous production of 1,2- and 1,3-propanediol

A process for the simultaneous production of 1,2- and 1,3-propanediol from glycerol, said method comprising:

• (a) dehydrating glycerol with formation of an aqueous solution containing acrolein and hydroxyacetone by feeding a glycerol-water mixture with a glycerol content of 10 to 40 wt % in the gas phase at 250.degree. to 340.degree. C. over an acidic solid catalyst with an H.sub.0 value (Hammett acidity function) of less than +2 and condensing the gaseous product stream to the aqueous solution mentioned;
• (b) hydrating the acrolein contained in the condensed product stream to 3-hydroxypropionaldehyde by treating the condensed product stream of stage (a) at 20.degree. to 120.degree. C. in the presence of an acidic hydration catalyst;
• and
• (c) catalytically hydrogenating the 3-hydroxypropionaldehyde and hydroxyacetone contained in the aqueous reaction solution of stage (b) to 1,3- and 1,2-propanediol by freeing the reaction solution of stage (b) from unreacted acrolein and subsequently hydrogenating the reaction solution using a hydrogenation catalyst and separating the reaction mixture of stage (c) into 1,2- and 1,3-propanediol by distillation.