# US 11,897,836 B2 · Process for the preparation of methionine

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- Number: US 11,897,836 B2
- Document ID: US11897836B2
- Status: Granted
- Kind: B2
- Application number: 17/618,145
- Filed: 2020-06-08
- Published: 2022-07-21
- Granted: 2024-02-13
- Earliest claimed: 2019-06-13
- Assignees: Evonik Operations GmbH
- Applicants: Evonik Operations GmbH
- Inventors: Jürgen Bilz; Cornelia Borgmann; Achim Fischer; Lucas Geist; Anja Nordschild; Christian Renner; Christian Reus; Axel Ronneburg
- Web page: https://patentgrep.com/patent/US11897836B2

## CPC

- C07C 319/20: by reactions not involving the formation of sulfide groups
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

The present invention relates to a process for the preparation of methionine comprising the step of contacting a solution or suspension comprising 2-amino-4-(methylthio)butanenitrile and/or 2-amino-4-(methylthio)butaneamide with water in the presence of a catalyst to give a methionine comprising mixture, wherein the catalyst comprises CeO2 comprising particles, wherein the CeO2 comprising particles have a BET surface area of from 175 to 300+/−10% m2/g measured according to DIN ISO 9277-5 (2003), a mean maximum Feret diameter xFmax, mean of from 3+/−10% to 40+/−10% nm and a mean minimum Feret diameter xFmin, mean of from 2+/−10% to 30+/−10% nm, both measured according to DIN ISO 9276-6 (2012).

## Claims

### Claim 1

A process for producing methionine, the process comprising contacting a solution or suspension comprising at least one selected from the group consisting of 2-amino-4-(methylthio)butanenitrile and 2-amino-4-(methylthio)butaneamide with water in the presence of a catalyst to give a methionine comprising mixture, wherein the catalyst comprises CeO2 comprising particles, wherein the CeO2 comprising particles have a BET surface area of 225+/−10% to 300+/−10% m2/g measured according to DIN ISO 9277-5 (2003), a mean maximum Feret diameter xFmax, mean of 3+/−10% to 40+/−10% nm, a mean minimum Feret diameter xFmin, mean of 2+/−10% to 30+/−10% nm, and a mean aspect ratio xFmin, mean/xFmax, mean of 0.55+/−10% to 0.80+/−10%, each measured according to DIN ISO 9276-6 (2012).

### Claim 2 (depends on 1)

The process of claim 1, wherein the catalyst comprises 25 to 100 wt.-% CeO2, based on a total weight of the catalyst.

### Claim 3 (depends on 1)

The process of claim 1, wherein the CeO2 comprising particles comprise 50 to 100 wt.-% CeO2, based on a total weight of the CeO2 comprising particles.

### Claim 4 (depends on 1)

The process of claim 1, wherein the BET surface area of the CeO2 comprising particles is 225+/−10% to 265+/−10% m2/g.

### Claim 5 (depends on 1)

The process of claim 1, wherein the CeO2 comprising particles have a lattice plane distance of 0.24+/−10% to 0.32+/−10% nm.

### Claim 6 (depends on 1)

The process of claim 1, wherein the CeO2 comprising particles comprise octahedral particles.

### Claim 7 (depends on 1)

The process of claim 1, wherein the CeO2 comprising particles have a mean equivalent circular diameter xA, mean of 3+/−10% to 30+/−10% nm, measured according to DIN ISO 9276-6 (2012).

### Claim 8 (depends on 1)

The process of claim 1, wherein the CeO2 comprising particles have a crystallinity of at least 50%.

### Claim 9 (depends on 1)

The process of claim 1, wherein the contacting is performed at a temperature no greater than 90° C. with a 2-amino-4-(methylthio)butanenitrile comprising solution or suspension.

### Claim 10 (depends on 1)

The process of claim 1, further comprising contacting the methionine comprising mixture with water in the presence of the catalyst.

### Claim 11 (depends on 10)

The process of claim 10, wherein the contacting of the methionine comprising mixture is performed at a temperature of 70 to 140° C.

### Claim 12 (depends on 1)

The process of claim 1, further comprising separating the catalyst from the methionine comprising mixture by a continuous cross flow filtration.

### Claim 13 (depends on 1)

The process of claim 1, wherein the method further comprises vacuum distilling the methionine comprising mixture or stripping the with water vapor following the contacting.