Patent ID: 8329951

Claim:
A process for preparing diphenylmethanediamine, comprising: reacting aniline with formaldehyde in the presence of an acid in an aqueous medium to form a reaction product comprising diphenylmethanediamine, water and the acid; neutralizing the acid in the reaction product by mixing ammonia with the reaction product to form a neutralized product; separating the neutralized product into an aqueous phase and an organic phase; first contacting the aqueous phase with at least one of an alkaline earth metal oxide and an alkaline earth metal hydroxide to form ammonia gas; then second contacting the ammonia gas with the alkaline earth metal oxide to dry the ammonia gas and to form the alkaline earth metal hydroxide; returning the ammonia gas to the reacting step; and returning the alkaline earth metal hydroxide formed in the first contacting step to the second contacting step.