GB957102A - Improvements relating to processes for the production of urea - Google Patents

Abstract

Carbonyl sulphide for use in the production of urea (see Division C2) is obtained by reading carbon monoxide or a gas containing it with sulphur vapour at 300-700 DEG C. for 1-20 seconds. The reaction may be carried out in a reactor filled with ceramic material, which may be coated with a heavy metal sulphide, such as molybdenum or tungsten sulphide, as catalyst, at 550-700 DEG C. for 5-20 seconds. The reaction is preferably carried out with more than a 25% excess of sulphur. The small amount of CS2 in the reaction gas can be removed by washing it out with a suitable solvent or adsorbing it on activated carbon; or it may be removed by passage through a tower containing sulphur, sulphur for the reaction being taken from this tower and vaporized, addition of CO2 then converting the CS2 into COS. The mixture of reactants can also be obtained by passing pre-heated CO-containing gas through liquid sulphur.ALSO:Urea is obtained by reacting carbon monoxide or a carbon monoxide-containing gas with sulphur vapour at 300-700 DEG C. for 1-20 seconds to obtain carbonyl sulphide COS, cooling, adding ammonia and passing the mixture at 60-100 DEG C. over activated carbon. The first step may be carried out or reactor filled with ceramic material, which may be coated with a heavy metal sulphide catalyst, at 550-700 DEG C. for 5-20 seconds. The activated carbon in the second step may be stationary in one or more vertical towers, or may be moved countercurrent to the reactants. The urea deposited on the activated carbon may be dissolved in water and the solution concentrated to crystallise the urea.