Stamicarbon, N.V. v. Chemical Construction Corp.

This interference proceeding involves an alleged improvement in the process of synthesizing urea from carbon dioxide and ammonia. The prior art taught that when carbon dioxide and excess ammonia are subjected to high pressure in a reaction vessel a reversible reaction occurs in which is formed an intermediate product called ammonium carbamate. That intermediate product in turn decomposes into urea and water. The process stream comes from the high pressure reaction vessel as a mixture of excess ammonia, unconverted ammonium carbamate, urea and water. The end product of the process is a liquid…