Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2001-12-19
2002-08-20
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S453000, C564S461000
Reexamination Certificate
active
06437186
ABSTRACT:
The invention relates to an improved process for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine, hereinbelow also named isophorone diamine or abbreviated to IPDA, from 3-cyano-3,5,5-trimethylcyclohexanone, hereinbelow also named isophorone nitrile or abbreviated to IPN, by hydrogenation through to amine in the presence of a formed Raney hydrogenation catalyst based on cobalt. The invention preferably includes a first stage for the at least partial conversion of isophorone nitrile into isophorone nitrilimine and a second stage for the hydrogenation of the reaction mixture through to amine in the presence of a fixed-bed Raney hydrogenation catalyst based on cobalt. The process enables isophorone diamine to be prepared at yields as high as or higher than those of the methods known hitherto while simultaneously utilising markedly lower quantities of catalyst.
Isophorone diamine is used as a starting material for the preparation of isophorone diisocyanate, as an isocyanate component for polyurethane systems, as an amine component for polyamides and as a curing agent for epoxy resins. Isophorone diamine is in many instances prepared from isophorone nitrile, with the carbonyl group being converted into an amino group and the nitrile group into an aminomethyl group in the presence of ammonia, hydrogen and hydrogenation catalysts. The starting material, isophorone nitrile can be obtained in known manner by an addition reaction between hydrogen cyanide and isophorone (q.v. Example, DE-OS 39 42 371, for example).
Raney catalysts based on cobalt are frequently preferred because of their good catalytic properties in the synthesis of isophorone diamine from isophorone nitrile or isophorone nitrilimine and their substantially simpler preparation in comparison with supported catalysts.
Raney catalysts, also known as activated metal catalysts, comprise an alloy of at least one catalytically active metal and at least one alkali-leachable metal. Aluminium is predominantly utilised for the alkali-soluble alloy component, but other metals such as, for example, zinc and silicon are also usable. The leachable component is dissolved out by the addition of alkali to the alloy, thus activating the catalyst.
Powdered catalysts have the disadvantage of being utilisable only in a batch process and requiring costly separation from the reaction media after the catalytic reaction. For this reason, among others, it is preferable to carry out the preparation of isophorone diamine in continuous processes. This requires fixed-bed catalysts which, in addition to having good catalytic activity, must also be sufficiently strong for continuous operation.
Patent specification DE 195 40 191 describes a two-stage process for the preparation of isophorone diamine. In this process isophorone nitrile is first converted with ammonia into the corresponding imine in the presence or in the absence of an imination catalyst, and the product mixture which is obtained is hydrogenated to isophorone diamine with the addition of hydrogen. A formed Raney catalyst based on cobalt serves as the hydrogenation catalyst. In addition to the catalyst alloy of cobalt and aluminium, the catalyst also contains further metallic cobalt which, as a binder, ensures the necessary stability of the formed body. The disadvantage of this process is that the cobalt added as the binder has only low catalytic activity, thus reducing the activity of the catalyst below that of binder-free catalysts. As a result the amount of catalyst or of the metal cobalt required is relatively large. The result is high capital costs for the cobalt as well as for reactor design, occasioned, for example, by the great weight of the catalysts.
This disadvantage is avoided in the preparation of isophorone diamine as described in document EP 0 880 996. For the hydrogenation a formed cobalt catalyst of the Raney type is used which, before activation by leaching of the aluminium, comprises exclusively a cobalt-aluminium alloy. This catalyst has the advantage over the catalyst used in document DE 19540191 of a markedly lower bulk density of only 1.2 kg/l. Despite the lower bulk density, the hydrogenation with the catalyst comprising exclusively the catalyst alloy leads to slightly higher yields for the same catalyst mass. The disadvantage of the method described in EP 0 880 996 lies in the fact that the catalyst used, however, still has very high bulk densities, relative to the catalyst according to the invention.
Document DE 199 33 450.1 describes metal catalysts which are present in the form of hollow bodies, preferably in the form of hollow spheres. These catalysts have a low bulk density of from 0.3 to 1.3 g/ml. In addition to the catalysts, their use in hydrogenation reactions is furthermore claimed. The Examples mention activity tests in respect of the hydrogenation of nitrobenzene to aniline, in which when the hollow spherical catalysts are used, hydrogen consumption, and hence the activity of the catalyst, is markedly higher per gramme of catalyst than when a comparison catalyst is used. However, the preparation of isophorone diamine with use of the catalysts described is not mentioned as such.
The object of the present invention is therefore to develop a process for the preparation of isophorone diamine from isophorone nitrile, in which the hydrogenation through to amine is carried out with a fixed-bed Raney hydrogenation catalyst which, while having a substantially lower bulk density than comparable catalysts, has the same or better hydrogenating activity. It is a further aim of the invention to achieve the same or better conversion rates of isophorone nitrile or isophorone nitrilimine, while utilising less catalyst material than in known processes.
The invention on which this rests has surprisingly shown that with the preparation of isophorone diamine from isophorone nitrilimine or isophorone nitrile by hydrogenation through to amine with the aid of the hollow-body-form catalysts (preferably cobalt catalysts) of the Raney type described in the document DE 199 33 450.1 markedly higher conversion rates can be obtained per unit of mass of catalyst than with comparable catalysts. This observation is surprising inasmuch as it cannot necessarily be taken that the hollow-body-form (cobalt) catalyst reaches the required activities in the specific case of the hydrogenation of isophorone nitrile or isophorone nitrilimine.
The invention provides a process for the preparation of isophorone diamine by hydrogenation through to amine of mixtures containing isophorone nitrile or isophorone nitrilimine in the presence of at least ammonia and hydrogen, in which a formed Raney hydrogenation catalyst is used as the hydrogenation catalyst, which is characterised in that the Raney catalyst is present in the form of hollow bodies.
In one embodiment of the invention a Raney catalyst based on cobalt and/or based on nickel and/or based on copper and/or iron may be used as the Raney catalyst.
This process has the advantage that isophorone diamine can be prepared with markedly less catalyst material but at conversion rates the same as or better than has been possible hitherto in accordance with the prior art.
The advantage on which this invention is based is achieved by the use of Raney catalysts in the form of hollow bodies, in particular on the basis of cobalt and/or on the basis of nickel and/or on the basis of copper and/or iron. The catalysts used in the process according to the invention may be prepared in accordance with the method described in DE 199 33 450.1. In accordance with this method, for example, a mixture of a cobalt alloy powder with a leachable metal, preferably aluminium, an organic binder and optionally water as well as promoters is applied to spheres prepared from a thermally removable material. Expanded polystyrene spheres may preferably be used. The mixture containing the metal alloy may preferably be applied to the polymer spheres in a fluidised bed. From 0.0-10 wt. % polyvinyl alcohol and/or from 0.0-3 wt. % glycerol may preferably be utilised as the org
Berweiler Monika
Finke Norbert
Jaeger Bernd
Lettmann Christian
Ostgard Daniel
Barts Samuel
Degussa - AG
Venable
LandOfFree
Process for the preparation of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the preparation of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2961893