D,L-methionine production via the carbonate process
By Chemical Engineering |
Methionine is an essential amino acid that is not synthesized by animals, so it must be obtained from their diets. Synthetic methionine is traditionally commercially available in two varieties: D,L-methionine (DLM), a racemic mixture of the two stereoisomers, and methionine hydroxy analog (MHA). For animal nutrition, the two are equivalent. Globally, 98% of methionine produced is used as an animal feed additive, especially in the poultry market. Methionine is also used in pharmaceuticals and cosmetics.
In the process shown in Figure 1, DLM is obtained via the carbonate process from 3-methylthiopropionaldehyde (MMP) and hydrogen cyanide (HCN), without forming co-products. The process presented here is similar to one developed by Evonik Industries AG (Essen, Germany; www.evonik.com), and can be divided into four main areas: hydantoin production; hydantoin hydrolysis; DLM production and filtration; and drying. Hydantoin corresponds to the intermediate 5-(2-methylmercaptoethyl)-hydantoin generated in the process.
FIGURE 1. D,L-methionine production via carbonate process
Hydantoin production. MMP, HCN and an aqueous solution of carbon dioxide (CO2) and ammonia (NH3) are fed to the hydantoin primary reactor. A gas stream containing…