Synthesis of diamine diphenyl methane (DADPM) and its higher homologues on delaminated zeolites: a challenge for a non-polluting process

Delaminated zeolitic materials ITQ-2 and ITQ-6 show excellent activity for the production of DADPM and longer catalyst life than conventional zeolite. Exfoliated materials are free of diffusion hindrance and present full accessibility to their acid sites. High yields in primary amines are achieved even when working with low aniline-formaldehyde (A-F) ratios and small amounts of water. The ratio of 4,4′/(2,2′+2,4′) DADPM can be modified by changing the structure of the delaminated materials. These catalysts allow the replacement of HCl in the current homogeneous process, avoiding the production of a substantial amount of wastes.