# US 5,705,700 A · Process for preparing a mixture of cyclohexylamine and dicyclohexylamine

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- Number: US 5,705,700 A
- Document ID: US5705700A
- Status: Granted
- Kind: A
- Application number: 08/755,512
- Filed: 1996-11-22
- Granted: 1998-01-06
- Earliest claimed: 1995-12-08
- Assignees: Bayer Aktiengesellschaft
- Inventors: Gerhard Darsow; Gerd-Michael Petruck; Wilfried Niemeier
- Web page: https://patentgrep.com/patent/US5705700A

## CPC

- C07C 209/72: by reduction of six-membered aromatic rings
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

To prepare a mixture of cyclohexylamine and dicyclohexylamine by catalytic hydrogenation of aniline at elevated temperature and elevated H.sub.2 pressure, the catalyst system used comprises two reduced, unsupported catalysts A and B which are prepared from pressed element (hydr)oxide powders. Catalyst A comprises one or more of Fe, Co, Ni, also Mn, Cu and one or more of Ca, Sr, Ba. Catalyst B comprises one or more of Fe, Co, Ni, also Mn, Si and Mg.

## Claims

### Claim 1

A process for preparing a mixture of a cyclohexylamine and a dicyclohexylamine of the formulae ##STR3## by catalytic hydrogenation of an aniline of the formula ##STR4## where, in the formulae, R.sup.1 and R.sup.2 are, independently of one another, hydrogen, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy,
at a reaction temperature of from 140.degree. to 260.degree. C. and an H.sub.2 pressure of from 10 to 400 bar, wherein the catalyst system used comprises two reduced, unsupported supported catalysts A+B comprising pressed element (hydr)oxide powders in which the following element proportions are present:
for catalyst A:
4- 60% by weight of one or more of Fe, Co, Ni;
10-20% by weight of Mn;
0.05-1.5% by weight of Cu; and
0.2-5% by weight of one or more of Ca, Sr, Ba; and
for catalyst B:
30-50% by weight of one or more of Fe, Co, Ni;
3-10% by weight of Mn;
5-15% by weight of Si; and
2-8% by weight of Mg;
where, in A and B, the remainder to 100% by weight is oxygen and the percentages are based on the total weight of the respective catalyst A or B.

### Claim 2 (depends on 1)

The process of claim 1, wherein the element from the group consisting of Fe, Co and Ni which is used is Co or Ni or a Co/Ni mixture.

### Claim 3 (depends on 2)

The process of claim 2, wherein the element from the group consisting of Fe, Co and Ni which is used is Co.

### Claim 4 (depends on 1)

The process of claim 1, wherein the element from the group consisting of Ca, Sr and Ba which is used is Sr or Ba or an Sr/Ba mixture.

### Claim 5 (depends on 4)

The process of claim 4, wherein the element from the group consisting of Ca, Sr and Ba which is used is Ba.

### Claim 6 (depends on 1)

The process of claim 1, wherein the catalysts A and B have a compressive strength of 200-800N/cm.sup.2 on flat pressed surfaces, a compressive strength of 50-200N, measured as force, on curved pressed surfaces and an internal surface area of 30-200 m.sup.2.

### Claim 7 (depends on 6)

The process of claim 6, wherein the compressive strength on flat pressed surfaces is 250-600N/cm.sup.2.

### Claim 8 (depends on 6)

The process of claim 6, wherein the compressive strength on curved pressed surfaces, measured as force, is 80-140N.

### Claim 9 (depends on 6)

The process of claim 6, wherein the internal surface area is 80-160 m.sup.2 /g.

### Claim 10 (depends on 1)

The process of claim 1, wherein the catalyst A and B are used in a weight ratio of from 0.5 A:9.5 B to 9.5 A:0.5 B.

### Claim 11 (depends on 1)

The process of claim 1, wherein the reaction is carried out continuously in the downflow mode over fixed-bed catalysts and the weight hourly velocity is 0.1-3 kg of aniline per liter of catalyst and hour.

### Claim 12 (depends on 11)

The process of claim 11, wherein the weight hourly velocity is 0.15-1.5 kg of aniline per liter of catalyst and hour.

### Claim 13 (depends on 1)

The process of claim 1, wherein the reaction is carried out at an H.sub.2 pressure of 20-350 bar.

### Claim 14 (depends on 13)

The process of claim 13, wherein the H.sub.2 pressure is 100-300 bar.

### Claim 15 (depends on 1)

The process of claim 1, wherein the reaction is carried out at a temperature of 160.degree.-230.degree. C.

### Claim 16 (depends on 1)

The process of claim 1, wherein the catalyst A and B are, prior to use, reduced separately or together by treatment with hydrogen at 160.degree.-240.degree. C. and 10-400 bar, with the hydrogen being used as H.sub.2 /inert gas mixture at the beginning of the reduction and the proportion of inert gas being completely removed during the course of the reduction.

### Claim 17 (depends on 1)

The process of claim 1, wherein the unsubstituted or substituted aniline is diluted with 10-100% by weight of a reaction-inert solvent, based on the unsubstituted or substituted aniline.

### Claim 18 (depends on 17)

The process of claim 17, wherein the unsubstituted or substituted aniline is diluted with 10-40% by weight of a reaction-inert solvent, based on the unsubstituted or substituted aniline.