Abstract: A catalytic process for hydrogenating aromatic di- and polyamines with the aid of a selected catalyst system is provided, which comprises a mixture of a first heterogeneous catalyst and a second heterogeneous catalyst and a nitro compound (nitrate and/or nitrite salt). The first and second heterogeneous catalyst each independently comprise a metal selected from the group consisting of Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd and/or Pt and the metal selected for the second heterogeneous catalyst is different from the metal selected for the first heterogeneous catalyst. Hydrogenation of aromatic rings having two or more amino groups bound to the aromatic ring produces cycloaliphatic di- and polyamines, which are useful chemical intermediates, e.g., for further reaction with epoxides or isocyanates. The amino groups may also be converted to isocyanates via reaction with phosgene. The resulting cycloaliphatic di- and polyisocyanates may also be used as monomers for making polymers.

Abstract: A catalytic process for hydrogenating aromatic di- and polyamines with the aid of a selected catalyst system is provided, which comprises a mixture of a first heterogeneous catalyst and a second heterogeneous catalyst and a nitro compound (nitrate and/or nitrite salt). The first and second heterogeneous catalyst each independently comprise a metal selected from the group consisting of Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd and/or Pt and the metal selected for the second heterogeneous catalyst is different from the metal selected for the first heterogeneous catalyst. Hydrogenation of aromatic rings having two or more amino groups bound to the aromatic ring produces cycloaliphatic di- and polyamines, which are useful chemical intermediates, e.g., for further reaction with epoxides or isocyanates. The amino groups may also be converted to isocyanates via reaction with phosgene. The resulting cycloaliphatic di- and polyisocyanates may also be used as monomers for making polymers.