Abstract: Processes suitable for purifying aromatic-containing feed streams, and processes using such purified streams are described, wherein the purification processes comprise: (a) providing a process feedstream comprising an aromatic component; and (b) bringing the process feedstream into contact with a first zeolite and a second zeolite; wherein the first zeolite has a mean pore size of 0.3 to 0.5 nm, and wherein the second zeolite has a mean pore size of 0.6 to 0.8 nm.

Abstract: In a process for preparing mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number by two-stage reaction of the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, separation of the excess phosgene and solvent after the phosgenation is complete and thermal treatment of the reaction product, the mass ratios of phosgene to hydrogen chloride in the residence time apparatus of the second stage of the phosgenation are at the same time 10-30:1 in the liquid phase and 1-10:1 in the gas phase.