Patent ID: 7329785

Claim:
A process for preparing 1,3-propanediol via hydrogenation of 3-hydroxypropanal comprising the steps of: (a) preparing an aqueous mixture of 3-hydroxypropanal, (b) passing the aqueous 3-hydroxypropanal mixture to a hydrogenation zone wherein the hydrogenation zone is comprised of at least two stages wherein the hydrogenation in the first stage is carried out under hydrogenation conditions at a temperature in the range of about 50 to about 130° C. in the presence of a fixed bed or slurry hydrogenation catalyst and wherein an acidic cocatalyst, which is selected from the group consisting of acidic zeolites, acid form cationic exchange resins, heteropolyacids, and soluble acids, is added in or present in at least one of the later stages, and the hydrogenation in said later stages is carried out under hydrogenation conditions at a higher temperature than that of the first hydrogenation stage and in the range of about 70 to about 155° C. in the presence of a fixed bed or slurry hydrogenation catalyst to form an aqueous solution of 1,3-propanediol, wherein when the acidic cocatalyst is a soluble acid the soluble acid provides a pH from about 2 to about 5.5; and (c) recovering said 1,3-propanediol.