Patent ID: 8759591

Claim:
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 H 12 MDA, 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 % H 6 MDA, except for the solvent; and b) separating the reaction solution obtained from step a) by conventional means to obtain H 12 MDA with desired purity and recycle accumulated un-reacted MDA and intermediate product to the hydrogenation reaction.