Patent ID: 8716517
Filing Date: 2014-05-06
Classification: C01B,C07C,Y02P

Abstract:
1. A process for preparing a diisocyanate, the process comprising: separately vaporizing a first feed stream comprising a diamine and a second feed stream comprising phosgene, to obtain a first and a second feed stream in the gas-phase; separately heating the first and second feed stream in the gas-phase to a reaction temperature for gas-phase phosgenation; and subsequently gas-phase phosgenating the diamine to obtain the diisocyanate, wherein waste heat from a plant for preparing chlorine by oxidizing hydrogen chloride in the presence of a heterogeneous catalyst, the Deacon process, is utilized for the vaporizing and the heating, and wherein a secondary heat transfer medium is utilized as heat transfer medium for indirect heat transfer to the feed streams for the gas-phase phosgenation.