Patent ID: 6924385

Claim:
A method for synthesizing an aliphatic isocyanate from an aromatic isocyanate which has one or more aromatic rings and one or more isocyanate groups bonded directly, indirectly or both directly and indirectly to one or more of the aromatic rings, the method comprising: i. urethanizing the aromatic isocyanate to form an aromatic urethane, wherein the urethanizing is carried out continuously or batchwise, in the presence or absence of a solvent or solvent mixture, and in the presence or absence of a catalyst, at temperatures of 20° C. to 160° C., and under normal pressure; ii. hydrogenating the aromatic urethane with hydrogen in the presence of a supported catalyst to form a hydrogenated urethane, where the supported catalyst comprises as an active metal, applied on a catalyst support, ruthenium, alone or together, with at least one metal of Group I, VII or VIII of the Periodic Table, wherein the proportion of the active metal is 0.01 to 20 wt % relative to the weight of the supported catalyst, and wherein the catalyst support has a BET surface area from greater than 30 m 2 /g to less than 70 m 2 /g, and more than 50% of the pore volume of the catalyst support is comprised of macropores with a pore diameter of larger than 50 nm, and less than 50% of the pore volume of the catalyst support is comprised of mesopores with a pore diameter of 2 to 50 nm; and iii. dissociating the hydrogenated urethane to the aliphatic isocyanate.