Phosphorus penta:sulphide continuous prodn. in 2 stages - with addn. of reactants to vapour phase in first small reactor to assist heat exchange

摘要

Continuous prodn. of P pentasulphide (I) involves reacting yellow P with liq. S at above the m.pt. A fluid P sulphide (II) melt contg. over 28.2% P is produced in a first stage in a small reactor and converted to (I) by adding S in a second stage in a large reactor. The novel features are that in the first stage, the reactants are introduced into the vapour phase above the liq. level, so that vapour forms at the surface of the boiling liq. and (II) contg. at least 50% P4S3 forms in the vapour phase, and the (II) vapour is condensed in the condenser and introduced into the (II) melt. ADVANTAGE - The cost of mfr. and safety precautions is reduced, operation is safer than usual and the plant capacity is improved. The low m.pt. of a (II) mixt. with a high P4S3 content facilitates heat exchange, so that the heat exchanger system can operate at normal or slightly elevated pressure, instead of the usual high pressure. Corrosion in the (I) condenser is also reduced. Injecting the reactants into the vapour phase prevents the nozzles becoming blocked.