Process for the production of di- and polyamines of the diphenylmethane series

Abstract

The invention relates to a production process for di- and polyamines of the diphenylmethane series by the rearrangement of a condensation product of aniline and a methylene group-supplying agent preferably selected from the group consisting of aqueous formaldehyde solution, gaseous formaldehyde, para-formaldehyde, trioxane and mixtures thereof, wherein said condensation product is reacted in the presence of at least one silica-alumina catalyst, said catalyst having a surface area as determined by the BET method carried out according to ASTM D3663-03 (2015) of from 200 m2/g to 520 m2/g, preferably of from 350 m2/g to 495 m2/g, particularly preferably of from 400 m2/g to 490 m2/g, a molar ratio of silica/alumina on the catalyst surface of A, an overall (bulk) molar ratio of silica/alumina of C, and a quotient B=A/C; said catalyst being characterised in that “low” A values (i.e. equal to or lower than 8.0) are combined with “high” B values (i.e. of from 1.50 to 3.00), and “high” A values (i.e. larger than 8.00, especially equal to or larger than 8.50) are combined with “low” B values (i.e. of from 0.15 to 1.40).

Dependencies are inferred from the claim text.