METHOD FOR PREPARING DIAMINO-DICYCLOHEXYL METHANE

摘要

Disclosed is a method for preparing diamino-dicyclohexyl methane (H 12 MDA) by hydrogenation of diamino-diphenyl methane (MDA). In the process, 4,4'-MDA used as the starting material is firstly hydrogenated to prepare 4,4'-H 12 MDA. When the activity of the catalyst is reduced, the feed is switched from 4,4'-MDA to the mixture of 2,4'-MDA and 4,4'-MDA, and then when the conversion is stabilized, the feed is switched to 4,4'-MDA again. The deactivated catalyst is activated on line by switching the feed to the mixture of 2,4'-MDA and 4,4'-MDA. 4,4'-H 12 MDA having the trans-trans isomer content of 16~24wt% is produced, and the mixture of 2,4'-H 12 MDA and 4,4'-H 12 MDA is also produced, wherein the content of 2,4'-H 12 MDA in the mixture is 4~15 wt%.