Process for preparation of di- and polyamines of the diphenylmethane series

Patent metadata

Field	Value
Publication number	US-2017137367-A1
Application number	US-201515317482-A
Country	US
Kind code	A1
Filing date	Jun 22, 2015
Priority date	Jun 24, 2014
Publication date	May 18, 2017
Grant date	—

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.

First claim

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 m 1 and formaldehyde being introduced at a mass flow rate m 2 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 m 1 and formaldehyde being introduced at a mass flow rate m 2 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 m 2 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 pro

Assignees

• Covestro Deutschland Ag

Inventors

• Knauf Thomas
• Wershofen Stefan
• Gruner Klaus-Gerd
• Hartjes Volker

Classifications

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title

• B01J19/0006

  Controlling or regulating processes (controlling or regulating in general G05) · CPC title

• C07C209/78 Primary

  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 title

• C07C209/84

  Purification · CPC title

• C02F1/04

  by distillation or evaporation · CPC title