A kind of regeneration method of catalyst in the continuous production process of 4,4'-diaminodicyclohexylmethane

Abstract

The invention discloses a catalyst regeneration process in the continuous production process of 4,4'-diaminodicyclohexylmethane (PACM20), comprising the following steps: using diaminodiphenylmethane as a raw material for continuous hydrogenation to prepare PACM20, when When the catalyst activity decreases, the feed is sequentially switched to liquid ammonia, alkali metal salt solution and liquid ammonia for corresponding regeneration treatment, and then the feed is switched to diaminodiphenylmethane to restore the catalyst activity. The process activates the deactivated catalyst on-line without stopping the vehicle to take out the deactivated catalyst. The operation is simple and the production efficiency is greatly improved.

Description

technical field [0001] The invention relates to a catalyst regeneration process in the continuous production process of 4,4'-diaminodicyclohexylmethane (PACM20). Background technique [0002] Diaminodicyclohexylmethane (PACM for short) has three stereoisomers with different thermodynamic properties: anti-trans, cis-trans, and cis-cis. Among them, PACM20 refers to the PACM product with an anti-trans isomer content of about 20wt%, which is mainly used in the fields of isocyanate synthesis and epoxy curing agent. Due to the stability and steric hindrance effect of the aromatic ring, the hydrogenation of MDA is very difficult. Most patents use supported noble metal catalysts to carry out intermittent catalytic reactions under high temperature and high pressure in stirred tank reactors or fixed bed reactors to obtain satisfactory yields and anti-anti-body ratios. [0003] Since noble metal catalysts are expensive, the life of the catalyst often determines the production cost of...

AI Technical Summary

Problems solved by technology

[0010] 1) Using oxygen or air to oxidize at high temperature to regenerate the catalyst is the most commonly used method. The operating temperature of this method is generally above 300°C, which can easily cause metal sintering on the surface of the catalyst, which will accelerate the deactivation of the catalyst.

Therefore, the traditional method of removing carbon deposits by high-temperature oxidation is not suitable for most fine chemicals and some hydrogenation catalysts.

[0011] 2) After the catalyst activity decreases, it is necessary to stop the vehicle to take out the old catalyst, and use separate equipment to activate the catalyst, which increases the investment cost and is not conducive to continuous production

[0012] 3) After the catalyst activity is reduced, the catalyst is activated during the hydrogenation reaction by introducing the isomers of MDA. A separate separation process is required to separate the isomers of the hydrogenation product, while 2,4’-H 12 MDA and 4,4'-H 12 The physical and chemical properties of MDA are close, which increases the difficulty of the separation process and is not conducive to industrial production