PROCESS FOR PREPARATION OF DI- AND POLYAMINES OF THE DIPHENYLMETHANE SERIES

• US 20170137367A1
• Filed: 06/22/2015
• Published: 05/18/2017
• Est. Priority Date: 06/24/2014
• Status: Active Grant

• Current Assignee: Covestro Deutschland AG
• Original Assignee: Covestro Deutschland AG
• Inventors: Knauf, Thomas, Wershofen, Stefan, Gruner, Klaus-Gerd, Hartjes, Volker
• Granted Patent: US 10,689,322 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 17/02 Separation of non-miscible liquids
• CPC Class Codes: B01D 3/12 Molecular distillation
• CPC Class Codes: B01D 3/14 Fractional distillation or use of a fractionation or rectification column
• CPC Class Codes: B01J 14/00 Chemical processes in general for reacting liquids with liquids; Apparatus specially adapted therefor B01J8/00, B01J19/08 take precedence
• CPC Class Codes: B01J 19/0006 Controlling or regulating processes controlling or regulating in general G05
• CPC Class Codes: B01J 19/245 placed in series
• CPC Class Codes: B01J 2219/00225 stopping the system or generating an alarm
• CPC Class Codes: C02F 1/04 by distillation or evaporation
• CPC Class Codes: C02F 2101/38 containing nitrogen
• CPC Class Codes: C02F 2103/36 from the manufacture of organic compounds
• CPC Class Codes: C07C 209/78 from carbonyl compounds, e.g. from formaldehyde, and amines having amino groups bound to carbon atoms of six-membered aromatic rings, with formation of methylene-diarylamines
• CPC Class Codes: C07C 209/84 Purification
• CPC Class Codes: C07C 209/86 Separation
• CPC Class Codes: C07C 211/50 with at least two amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials

Abstract

The present invention relates to a process for preparing di- and polyamines of the diphenylmethane series (MDA), a system for producing MDA and a process for operating a system for preparing MDA. The invention enables optimization of production standstills during operation of the MDA process with respect to time expenditure and optionally also with respect to energy and material consumption by means of a so-called recirculation mode for individual system components. During interruption of the process or interruption of the operation of individual system components, formaldehyde is not introduced into the reaction and the system components that are not affected by a revision, repair, or cleaning measure are operated in so-called recirculation mode. This enables, among other things, that only the affected system component can be put in standstill during the time period of the measure, which is advantageous in terms of productivity and economy of the process as well as in terms of the quality of the products produced.

Claims

1. A process for preparing diamines and polyamines of the diphenylmethane series, which comprises the steps:

IA) reaction of reacting aniline and formaldehyde in the absence of an acid catalyst in a reactor to form an aminal, with aniline being introduced at a mass flow rate m₁ and formaldehyde being introduced at a mass flow rate m₂ into the reactor, followed by separation of the reaction mixture obtained into an aqueous phase and an organic phase containing the aminal in a phase separation facility integrated into the reactor or in a separate phase separation apparatus;

IIA) reacting at least part of the organic phase containing the aminal which is obtained in step IA) with acid in a reactor, with the aminal reacting to form diamines and/or polyamines of the diphenylmethane series;

or

IB) reacting aniline and acid in a reactor;

IIB) reacting at least part of the reaction mixture obtained in step IB) with formaldehyde in a reactor to form diamines and polyamines of the diphenylmethane series, with the aniline-containing reaction mixture from step IB) being introduced at a mass flow rate m₁ and formaldehyde being introduced at a mass flow rate m₂ into the reactor of step IIB);

and the optional steps III) to VIII)

III) neutralizing the reaction mixture obtained in step IIA) or IB) in a reactor;

IV) separating the neutralized reaction mixture obtained in step III) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase in a separation vessel;

V) washing the organic phase with washing liquid in a washing vessel;

VI) separating the mixture obtained in step V) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase in a separation vessel;

VII) distilling the organic phase from step VI), with diamines and polyamines of the diphenylmethane series being separated off from water and aniline, giving a stream containing water and aniline; and

VIII) working up the aqueous phase from step IA) and/or the aqueous phase from step IV) and/or the aqueous phase from step VI) and/or the stream containing water and aniline from step VII) in a wastewater work-up facility;

wherein

in the case of a shutdown of one or more plant parts of steps I) to VIII), if these are carried out, the mass flow rate m₂ in step IA) or in step IIB) is reduced to zero and the output stream from at least one of the plant parts which have not been shut down is reused as feed stream to the respective plant part or an upstream plant part.

2. The process as claimed in claim 1 comprising the steps III) to VII).

3. The process as claimed in claim 1, wherein the output stream in all plant parts which have not been shut down, with the exception of the washing vessel used in step V) and the separation vessel used in step VI), is reused as feed stream to the respective plant part.

4. A plant for preparing diamines and polyamines of the diphenylmethane series, which comprises the plant parts:

IA) a reactor having an integrated phase separation facility or a reactor and a separate phase separation apparatus configured to react aniline and formaldehyde in the absence of an acid catalyst to form an aminal and configured to subsequently separate the reaction mixture obtained into an aqueous phase and an organic phase containing the aminal and

IIA) a reactor configured to react the organic phase containing the aminal obtained in the reactor IA) with acid;

or

IB) a reactor configured to react aniline with acid and

IIB) a reactor configured to react the reaction mixture obtained in the reactor IB) with formaldehyde;

and optionally

III) a reactor configured to neutralize of the reaction mixture from IIA) or IIB);

IV) a separation vessel configured to separate the neutralized reaction mixture from III) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase;

V) a washing vessel configured to wash the organic phase from IV) by means of washing liquid;

VI) a separation vessel configured to separate the mixture from V) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase;

VII) a distillation apparatus configured to distill the organic phase from VI) to give diamines and polyamines of the diphenylmethane series and a stream containing water and aniline; and

VIII) a wastewater work-up facility configured to work-up the aqueous phase from IA) and/or the aqueous phase from IV) and/or the aqueous phase from VI) and/or the stream containing water and aniline from VII);

wherein

the plant is configured in such a way that no further Introduction of formaldehyde into the reactor IA) or IIB) takes place in the case of a shutdown of one or more of the plant parts I) to VIII), insofar as these are present, and the output stream can be recirculated in at least one of the plant parts which have not been shut down and used as feed stream for the respective plant part or an upstream plant part.

5. The plant as claimed in claim 4 comprising the plant parts III) to VII).

6. The plant as claimed in claim 4, wherein the configuration of the plant for interruption of the introduction of formaldehyde when one or more plant parts are shut down is achieved by means of process control facilities.

7. The plant as claimed in claim 4, wherein the plant is configured so that the output stream can be recirculated in each plant part which has not been shut down, with the exception of the washing vessel V) and the separation vessel VI), insofar as these are present, and be used as feed stream to the respective plant part.

8. The plant as claimed in claim 4, wherein the plant is configured so that the output streams in all plant parts which have not been shut down can be simultaneously recirculated and used as feed streams.

9. The plant as claimed in claim 4, wherein the plant is configured so that the output streams in all plant parts which have not been shut down can be independently recirculated and used as feed streams.

10. The plant as claimed in claim 4, wherein the plant is configured so that

reactor IA) comprises an aniline feed conduit to the reactor, a siphon and a phase separator for separating off aniline, where, in the reactor IA), aniline can be circulated via the aniline feed conduit, the siphon and the phase separator and back to the aniline feed conduit,

or so that

reactor IB) comprises an aniline feed conduit which can be shut off, an acid feed conduit which can be shut off, a mixing apparatus and a heat exchanger for regulating the temperature of the reaction mixture, where the mixing apparatus in the reactor IB) is shut down after the aniline feed conduit and the acid feed conduit have been shut off.

11. The plant as claimed in claim 4, wherein the plant is configured so that

the reactor IIA) comprises a rearrangement tank, an aminal conduit and a rearrangement cascade, where, in the reactor IIA), the output stream can be circulated via the aminal conduit into the rearrangement tank, the rearrangement cascade and the aminal conduit into the rearrangement tank,

or so that

reactor IIB) comprises a feed conduit for the reaction product of aniline and acid which can be shut off or, if reactor IIB and IB are identical, in each case a separate feed conduit for aniline and acid, a feed conduit for formaldehyde which can be shut off, a mixing apparatus and a heat exchanger for regulating the temperature of the reaction mixture, where the mixing apparatus in the reactor IIB) is configured to be shut down after the feed conduit for formaldehyde has been shut off and after the feed conduit for the reaction product of aniline and acid has been shut off, or, if reactor IIB) and IB) are identical, after the feed conduit for aniline and the feed conduit for acid have been shut off.

12. A method of operating a plant for preparing diamines and/or polyamines of the diphenylmethane series, where the plant comprises the following plant parts:

IA) a reactor having an integrated phase separation facility or a reactor and a separate phase separation apparatus configured to react aniline and formaldehyde in the absence of an acid catalyst to form an aminal and configured to subsequently separate the reaction mixture obtained into an aqueous phase and an organic phase containing the aminal and

IIA) a reactor configured to react the organic phase containing the aminal obtained in the reactor IA) with acid;

or

IB) a reactor configured to react aniline with acid and

IIB) a reactor configured to react the reaction mixture obtained in the reactor IB) with formaldehyde;

and optionally

III) a reactor configured to neutralize the reaction mixture from IIA) or IIB);

IV) a separation vessel configured to separate the neutralized reaction mixture from III) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase;

V) a washing vessel configured to wash the organic phase from V) by means of washing liquid;

VI) a separation vessel configured to separate the mixture from V) into an organic phase comprising diamines and polyamines of the diphenylmethane series and an aqueous phase;

VII) a distillation apparatus configured to distill the organic phase from VI) to give diamines and/or polyamines of the diphenylmethane series and a stream containing water and aniline; and

VIII) a wastewater work-up facility configured to work-up the aqueous phase from IA) and/or the aqueous phase from IV) and/or the aqueous phase from VI) and/or the stream containing water and aniline from VII);

wherein

to shut down one or more plant parts I) to VIII), if these are present, the following steps are carried out;

(i) a) stopping the introduction of formaldehyde into the reactor IA);

(ii) a) stopping the introduction of aniline into the reactor IA);

(iii) a) stopping the introduction of acid into the reactor IIA);

or

(i) b) stopping the introduction of formaldehyde into the reactor IIB);

(ii) b) stopping the introduction of acid into the reactor IB);

(iii) b) stopping the introduction of aniline into the reactor IB);

and

(iv) operating at least one plant part In such a way that the output stream from the respective plant part is used as feed stream to the respective plant part or an upstream plant part;

(v) shutting down of at least one plant part;

(vi) optionally opening the at least one plant part which has been shut down in step (v);

(vii) optionally performing a maintenance, cleaning and/or repair measure in the at least one plant part which has been shut down in step (v); and

(viii) optionally closing and optionally making inert the at least one plant part which has been shut down in step (v).

13. The method as claimed in claim 12, wherein the plant comprises the plants parts Ill) to VII).

14. The method as claimed in either claim 12, wherein, in step (iv), the output stream in all plant parts which have not been shut down, with the exception of the washing vessel V) and the separation vessel VI), insofar as these are present, is reused as feed stream for the respective plant part.

15. The method as claimed in claim 12, wherein, to restart the production process for preparing the diamines and polyamines of the diphenylmethane series, all plant parts are started up again after step (viii) in an order which is the reverse of the order of the shutdown or of the changing to recirculation of the output stream from the respective plant part as feed stream to the respective plant part.