Synthesis of ammonium cyanate and urea from NO over Pt, Os, Ru, and CuNi catalysts

Abstract

The synthesis of NH 4OCN and urea, recently reported to occur in good yields (>90%) over Pt and Rh catalysts, has been studied further over Pt, CuNi, Ru, and Os catalysts. The synthesis starts from NO, which is reduced to NH 4OCN with CO and H 2 diluted with He. Maximum yields of 98% at 360–400 °C, 70% at 390 °C, 28% at 250 °C, and 10% at 250 °C (based on 2 NO converted to NH 4OCN) were obtained for Pt, CuNi, Os, and Ru catalysts, respectively. The effects of temperature, flow rate, reactant concentrations, and pretreatment of the catalyst were studied for Pt catalysts. The mechanism of the formation of NH 4OCN and other nitrogen products is considered. Adsorbed NCO entities appear to play a central role as intermediates.