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US-12617750-B2 - Process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of Raney nickel and a basic co-catalyst

US12617750B2US 12617750 B2US12617750 B2US 12617750B2US-12617750-B2

Abstract

The present invention relates to a process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst and a basic co-catalyst containing potassium hydroxide, wherein the basic co-catalyst contains a further basic compound selected from the group consisting of alkaline hydroxides, alkaline earth hydroxides and ammonium hydroxides.

Inventors

  • Maxime HUCHEDE
  • Sandra Chouzier

Assignees

  • BASF SE

Dates

Publication Date
20260505
Application Date
20210324
Priority Date
20200325

Claims (14)

  1. 1 . A process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst and a basic co-catalyst containing potassium hydroxide, wherein the basic co-catalyst contains a further basic compound selected from the group consisting of alkaline hydroxides, alkaline earth hydroxides and ammonium hydroxides, wherein the alkaline hydroxides contain cesium hydroxide, wherein the alkaline earth hydroxides contain barium hydroxide, and wherein the ammonium hydroxides contain an ammonium hydroxide of the general formula NR 4 OH, wherein each R is independently from each other an alkyl group having from 1 to 16 carbon atoms.
  2. 2 . The process according to claim 1 , wherein the basic co-catalyst contains barium hydroxide Ba(OH) 2 .
  3. 3 . The process according to claim 1 , wherein the basic co-catalyst contains cesium hydroxide.
  4. 4 . The process according to claim 1 , wherein each R is independently from each other an alkyl group having from 1 to 4 carbon atoms.
  5. 5 . The process according to claim 4 , wherein each R is independently from each other methyl or butyl.
  6. 6 . The process according to claim 5 , wherein R is methyl.
  7. 7 . The process according to claim 5 , wherein R is n-butyl.
  8. 8 . The process according to claim 1 , wherein the basic co-catalyst contains from 50 to 95 mol-% of KOH and from 5 to 50 mol-% of the further basic compound.
  9. 9 . The process according claim 1 , wherein the basic co-catalyst contains from 70 to 90 mol-% of KOH and from 10 to 30 mol-% of the further basic compound.
  10. 10 . The process according to claim 9 , wherein the basic co-catalyst contains from 75 to 85 mol-% of KOH and from 15 to 25 mol-% of the further basic compound.
  11. 11 . The process according to claim 1 , wherein the basic co-catalyst is present in an amount of from 0.1 to 2.0 mol OH − /kg Ni.
  12. 12 . The process according to claim 1 , wherein the hydrogenation is carried out in hexamethylenediamine as solvent containing from 1 to 20% by weight of an aqueous solution of the basic co-catalyst.
  13. 13 . The process according to claim 1 , wherein the hydrogenation is carried out at a temperature of from 50 to 150° C. at a hydrogen pressure of from 1 to 100 bar.
  14. 14 . The process according to claim 1 , wherein the Raney nickel catalyst optionally comprises one or more dopants selected from chromium, titanium, molybdenum, tungsten, manganese, vanadium, zirconium, iron, and zinc.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national stage application (under 35 U.S.C. § 371) of PCT/EP2021/057591, filed Mar. 24, 2021, which claims benefit of European Application No. 20165609.7, filed Mar. 25, 2020, both of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The present invention relates to a process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst and a basic co-catalyst. BACKGROUND ART Hexamethylenediamine is a compound used in numerous applications, the main ones of which are the manufacture of polyamides such as poly(hexamethylene adipamide), more commonly known as PA 6,6, and the manufacture of hexamethylene diisocyanate. Several processes for manufacturing hexamethylenediamine have been proposed, which generally consist of a hydrogenation of adiponitrile (tetramethylene dicyanide) in the presence of a hydrogenation catalyst. Two types of process are utilized industrially that use different catalysts and different temperature and pressure conditions. Thus, a first type of hydrogenation process that is utilized and described in the literature consists in hydrogenating nitrile compounds in the presence of ammonia and under high pressure, with a ruthenium-based catalyst for example. Iron based catalysts under high pressure and temperature are also used. A second type of process consists in carrying out the hydrogenation of nitrile compounds under pressure pressure and at a not very high temperature, for example at 25° C. and 80 bar, in the presence of a basic compound and a catalyst based on Raney nickel. In the latter type of process, the hydrogenation of nitrile compounds to amines takes place in the presence of a catalyst based on optionally doped Raney nickel. These catalysts are prepared by the leaching of aluminium, from Ni—Al alloys, in a strongly alkaline medium. The catalysts obtained are composed of agglomerates of nickel crystallites, having a high specific surface area and a variable residual aluminium content. It is known that adiponitrile can react by hydrogenation to give a cyclic diamine, diaminocyclohexane (DCH). However, DCH is particularly troublesome since it has a boiling point close to the boiling point of the targeted amine and is therefore very difficult to separate. There is an industrial need for optimization of the hydrogenation of adiponitrile to hexamethylenediamine, by means of Raney nickel catalysts, especially with respect to the activity, the selectivity and the deactivation behaviour of the final catalyst. In particular, it is important to limit the formation of diaminocyclohexane in order to obtain a hexamethylendiamine which can be purified with a minimum capital cost and a minimum energy consumption. US 2003/0144552 A1 discloses the hydrogenation of adiponitrile to hexamethylene-diamine in the presence of Raney nickel doped with chromium in a solution containing hexamethylenediamine and KOH. The use of a further hydroxide is not described. It is an object of the present invention to provide a process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst which is characterized in a low formation of diaminocyclohexane (DCH) as side product. SUMMARY OF THE INVENTION The object is achieved by a process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst and a basic co-catalyst containing potassium hydroxide, wherein the basic co-catalyst contains a further basic compound selected from the group consisting of alkaline hydroxides, alkaline earth hydroxides and ammonium hydroxides. DETAILED DESCRIPTION Further alkaline hydroxides are hydroxides of Li, Na, Rb and Cs. Alkaline earth hydroxides are hydroxides of Mg, Ca, Sr and Ba. In one embodiment, the basic co-catalyst contains cesium hydroxide CsOH as further basic compound. In one preferred embodiment, the basic co-catalyst contains barium hydroxide Ba(OH)2 as further basic compound. In further preferred embodiments, the basic co-catalyst contains an ammonium hydroxide of the general formula NR4OH, wherein each R is independently from each other an alkyl group having from 1 to 16 carbon atoms, preferably from 1 to 4 carbon atoms. In particular preferred embodiments, each R in NR4OH is independently from each other methyl, ethyl, propyl or butyl. In a very preferred embodiment, each R in NR4OH is methyl, i.e. the basic co-catalyst contains tetramethylammonium hydroxide as further basic compound. In a further very preferred embodiment, each R in NR4OH is n-butyl, i.e. the basic co-catalyst contains tetra(n-butyl)ammonium hydroxide, as further basic compound. Preferably, the basic co-catalyst contains from 50 to 95 mol-% of KOH and from 5 to 50 mol-% of the further basic compound. More preferably, the basic co-catalyst contains from 70 to 90 mol-% of KOH and from