Dow considers enzymatic dehalogenation

Chlorinated propanes and butanes are low-value coproducts from the production of propylene oxide, epichlorohydrin, and butylene oxide at Dow Chemical Co. In a study of enzyme-based dehalogenation as a possible means of recovering feedstock materials from these streams, Dow has found a haloalkane dehydrogenase enzyme in the soil that can catalyze the conversion of 1,2,3-trichloropropane to dichlorohydrin, an epichlorohydrin precursor. The enzyme, which is very stable when immobilized, is used in a continuous-flow reactor. However, productivity is limited and the product inhibits activity of the enzyme, thus, random mutagenesis and gene recombination have been used to conduct directed evolution to improve the enzyme. The enzyme's catalytic power has been significantly increased. The tools developed include a mathematical model to link the performance of a soluble enzyme with its performance in a packed bed bioreactor.