# US 7,408,081 B2 · Process for treating an aqueous medium containing cyclohexanone oxime and cyclohexanone

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- Number: US 7,408,081 B2
- Document ID: US7408081B2
- Status: Granted
- Kind: B2
- Application number: 10/496,873
- Filed: 2001-12-04
- Published: 2005-03-24
- Granted: 2008-08-05
- Earliest claimed: 2001-12-04
- Assignees: Dsm IP Assets B.V.
- Inventors: Arno Benneker; Henk Oevering; Johannes A. L. Brouwers
- Web page: https://patentgrep.com/patent/US7408081B2

## CPC

- C07C 249/08: by reaction of hydroxylamines with carbonyl compounds
- C07C 249/14: Separation; Purification; Stabilisation; Use of additives
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

The invention relates to a process for treating an aqueous medium containing cyclohexanone oxime and cyclohexanone, said process comprising stripping the aqueous medium with steam, wherein said stripping is carried out at a pressure higher than 0.11 MPa. The invention also relates to a process for the preparation of cyclohexanone oxime, which involves stripping at a pressure higher than 0.11 MPa.

## Claims

### Claim 1

A process for preparing cyclohexanone oxime comprising:
passing an aqueous medium containing phosphate from a hydroxylammonium synthesis zone to a cyclohexanone oxime synthesis zone, from the cyclohexanone oxime synthesis zone to a stripping zone and from the stripping zone back to the hydroxylammonium synthesis zone,
in said hydroxylammonium synthesis zone, preparing hydroxylammonium by catalytically reducing nitrate or nitrogen oxide with hydrogen;
in said cyclohexanone oxime synthesis zone, preparing cyclohexanone oxime by reacting hydroxylammonium with cyclohexanone;
in said stripping zone, stripping the aqueous medium with steam; wherein said stripping is carried out at a pressure higher than 0.11 MPa.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the concentration of hydroxylammonium in the aqueous medium entering the cyclohexanone oxime synthesis zone is higher than 1.0 mol/l.

### Claim 3 (depends on 2)

The process according to claim 2, wherein the concentration of hydroxylammonium in the aqueous medium entering the cyclohexanone oxime synthesis zone is higher than 1.4 mol/l.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the stripping is carried out at a pressure higher than 0.15 MPa.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the superficial gas velocity of said steam is between 0.2 and 3 m/s.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the process comprises obtaining said steam by evaporating water from the aqueous medium.

### Claim 7 (depends on 1)

The process according to claim 1, wherein said stripping is carried out in a column.

### Claim 8 (depends on 1)

The process according to claim 1, wherein said column is a plate column or a packed column.

### Claim 9 (depends on 1)

The process according to claim 1, wherein the aqueous medium is an acidic aqueous medium.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the aqueous medium to be stripped has a pH of between 0 and 4.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the aqueous medium to be stripped contains 2.0-8.0 mol/l of phosphate, 0.5-8.0 mol/l of ammonium and 0.1-5.0 mol/l of nitrate.

### Claim 12 (depends on 1)

The process according to claim 1, wherein the joint content of cyclohexanone oxime and cyclohexanone in the aqueous medium to be stripped is less than 0.5 wt. %.

### Claim 13 (depends on 1)

The process according to claim 1, wherein said stripping is carried out in a stripping zone, and wherein the process comprises discharging a vapor stream from said stripping zone, said vapor stream having a pressure higher than 0.11 MPa.

### Claim 14 (depends on 13)

The process according to claim 13, wherein said vapor stream comprises steam and cyclohexanone.

### Claim 15 (depends on 13)

The process according to claim 13, wherein the process comprises exchanging heat of the vapor stream to a process liquid.

### Claim 16 (depends on 15)

The process according to claim 15, wherein said process liquid is a process liquid in a production process for caprolactam.

### Claim 17 (depends on 16)

The process according to claim 16, wherein said process liquid is mixture comprising toluene and cyclohexanone oxime.