Abstract: Phenyl isocyanates are removed from a solvent stream obtained from an MDI and/or PMDI manufacturing process by reaction in the presence of a carbodiimidization catalyst to form the corresponding N,N-diphenylcarbodiimides. The N,N-diphenylcarbodiimides can be recycled into the MDI and/or PMDI manufacturing process where they can react with MDI and/or PMDI to form uretonimines. The uretonimines have at most minimal effect on the properties and usefulness of the MDI and/or PMDI product and so can be left in the MDI and/or PMDI product.

Abstract: Organic isocyanates are converted to ureas by heating in the presence of certain cobalt, magnesium, chromium and lanthanide series organometallic catalysts. The process requires no water or other reactants. The process is particularly useful for removing small quantities of monoisocyanates from a solvent stream recovered from a polyisocyanate manufacturing process. The urea compounds in some instances can be recycled back into the polyisocyanate manufacturing process and reacted with polyisocyanate compounds to form biurets.

Abstract: Monoisocyanate impurities are removed from a process stream obtained when solvent is separated from a polyisocyanate product. The monoisocyanates are reacted with amine compounds at specific molar ratios to produce ureas. The ureas can be discarded by burning, landfilling or otherwise. Alternatively the ureas can be recycled back into the polyisocyanate manufacturing process, where they are formed into biuret compounds that can remain with the polyisocyanate product.