Method for intermittently producing 4,4′-diaminodicyclohexylmethane with a low amount of the trans-trans isomer

摘要

The present invention discloses a method for intermittently producing 4,4′-diaminodicyclohexyl methane (H12MDA) with a low amount of the trans-trans isomer thereof, which comprises: controlling the reaction process by stopping the reaction when, except for a solvent, the reaction solution comprises MDA of 0-5 wt % and H6MDA of 1-20 wt %; and b) separating the reaction solution obtained from step a) by conventional means to obtain H12MDA product with desired purity, and allowing the un-reacted material and intermediate product to be recycled to the reactor after being accumulated. The method of the present invention decreases the amount of the trans-trans isomer in H12MDA, increases the yield of the reaction, and reduces the production cost. The present invention also provides a post treatment process of the reaction mixture.

主权项

1. A method for intermittently producing 4,4′-diaminodicyclohexylmethane with a low amount of the trans-trans isomer, wherein the method comprises:
a) subjecting MDA to a hydrogenation reaction in an organic solvent at a reaction temperature of 120-190° C., and under a hydrogen pressure of 50-150 bar in the presence of a catalyst to generate H12MDA, wherein the hydrogenation reaction is stopped when the hydrogen consumption reaches 92-98 volume % of the theoretical hydrogen consumption required for complete hydrogenation of the MDA in order to obtain a reaction solution comprising 0-5 wt % MDA and 1-20 wt % H6MDA, except for the solvent; and b) separating the reaction solution obtained from step a) by conventional means to obtain H12MDA with desired purity and recycle accumulated un-reacted MDA and intermediate product to the hydrogenation reaction.