(2d) Mechanism of Production of 3-hydroxypropionic acid (3-HP) in the Shell PDO Process

The Shell PDO Process was developed by Shell in the 1990’s, culminating in the construction and operation of a 75 KTA production plant in Geismar, LA. The process involves the cobalt mediated hydroformylation of ethylene oxide into 3-hydroxypropionaldehyde in a wet ether solvent under 100 bar of syn gas. The aldehyde intermediate is separated from the cobalt catalyst via water extraction and subsequently hydrogenated to make 1,3-propanediol. In plant operations it was discovered that the aldehyde intermediate could be oxidized to 3-hydroxypropionic acid (3-HP) in the hydroformylation section of the plant. This oxidation took place under syn gas pressure and was mediated by a cobalt hydride. This talk will briefly introduce the process and present detailed information on this transformation and how the mechanism of conversion was elucidated via on-line analysis in a commercial production environment.