GB1060781A - Improvements relating to the production of urea - Google Patents

Abstract

Urea is prepared by reacting CO with sulphur vapour at 250 DEG -700 DEG C. for 0.01-20 seconds in the presence of a sulphide of a metal of Group V, VI, VII or VIII of the Periodic Table, cooling the resulting COS, adding NH3, and passing the mixture at 60 DEG -100 DEG C. over a microporous material (such as active alumina, silica gel, pumice or active carbon); with the proviso that when active carbon is used as the microporous material and the COS is produced at 300 DEG -700 DEG C., the reaction time for the production of the COS is not 1-20 seconds. The urea is produced on the microporous material, together with H2S; the latter may be desorbed with CO-containing gas which is then fed to the COS reactor. The urea is extracted from the reactor by means of liquid ammonia, or aqueous urea solutions obtained from previous extractions. More than one urea reactor may be used. The last reactor may be operated at below 40 DEG C., when residual NH3 is bound as NH4SH, which will react to form urea when another reactor is switched in and the temperature of the previously last reactor is raised.ALSO:Carbonyl sulphide is produced by reacting CO with sulphur vapour at 250-700 DEG C. for 0.01-20 seconds in the presence of a sulphide of a metal of Group V, VI, VII or VIII of the Periodic Table.