Recovery of adiponitrile from a mixture of adiponitrile, aminocapronitrile and hexamethylenediamine

A technology of bis-hexamethylenetriamine and cyanocyclopentylene imine, which is applied in the field of ADN and can solve problems such as the inability to separate BHMT from CPI

Inactive Publication Date: 2005-10-12
INVISTA TEXTILES (U K) LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, BHMT cannot be isolated from ADN together with CPI if simple fractional distillation is performed using conventional operating conditions (i.e. head pressure less than 20 mmHg)

Method used

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  • Recovery of adiponitrile from a mixture of adiponitrile, aminocapronitrile and hexamethylenediamine
  • Recovery of adiponitrile from a mixture of adiponitrile, aminocapronitrile and hexamethylenediamine

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Embodiment Construction

[0019] The process of the present invention was performed in a stepwise fashion (as opposed to a continuous, bulk operation) to evaluate the ability of the process to produce refined streams of HMD, ACN and ADN. Reference numbers are shown in parentheses. All percentages are by weight. The notation "ND" in the table indicates not detectable. Throughout the specification and drawings, the expressions "still pot" and "distillation column" are interchangeable.

[0020] Feed (22) was prepared by blending crude HMD with refined ACN and refined ADN. The nominal composition of the feed was: 40% HMD, 40% ACN and 20% ADN. Impurities consisting of conventional impurities such as hexamethyleneimine (HMI), diaminocyclohexane (DCH), BHMT, etc. are present in crude HMD. Air was bubbled through the feed mixture such that the THA in the feed was about 300 ppm.

[0021] All rectification columns (still pots) consisted of 2 inch diameter vacuum jacketed sections containing Sulzer BX wire m...

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Abstract

Process for the recovery of a purified adiponitrile (ADN) from a mixture of adiponitrile, aminocapronitrile and hexamethylenediamine, utilizing two sequential distillations: (1) a first distillation in which the mixture is distilled in a distillation column at a head pressure that causes at least 7% of the ADN to go into the distillate, along with bishexamethylenetriamine (BHMT) and 2-cyanocyclopentylideneimine (CPI), and (2) a second distillation in which the distillate from the first distillation is distilled in a second distillation column at a head pressure sufficient to cause minimum-temperature azeotropy between ADN and BHMT, thereby allowing the majority of the BHMT and CPI to be removed from the second distillation as distillate, and ADN, substantially free of both BHMT and CPI, to be removed as bottoms.

Description

Background of the invention [0001] The present invention relates to the recovery of unreacted ADN from a mixture of ADN, aminocapronitrile (ACN) and hexamethylenediamine (HMD) formed by the partial hydrogenation of adiponitrile (ADN). ADN can be obtained by hydrocyanation of butadiene (BD), hydrocoupling of acrylonitrile, ammonolysis of adipic acid or other processes. It is known that ADN can be partially hydrogenated to HMD and ACN by reacting ADN with hydrogen in the presence of heterogeneous catalysts, especially iron or Raney cobalt. This hydrogenation leads to the formation of undesirable by-products including bis-hexamethylenetriamine (BHMT) and high boiling tars. [0002] If this method is carried out by recycling unreacted ADN back to the hydrogenation reactor, BHMT will be recycled back to the reactor together with ADN, and as a result, BHMT can be expected to increase over time in the system, eventually accumulating to an unacceptable level. degree of acceptance. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D3/14C07C253/34C07C255/04C07C255/09
CPCB01D3/146B01D3/143Y10S203/20Y10S203/09C07C253/34C07C255/09C07C255/04
Inventor J·J·奥斯特迈尔L·S·斯科特J·D·哈斯廷斯
Owner INVISTA TEXTILES (U K) LTD
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