FIELD: chemistry.
SUBSTANCE: invention relates to a method of producing adiponitrile through double hydrocyanation of a hydrocarbon mixture, which is a C4 petroleum fraction and contains at least one diolefin. The method involves a first hydrocyanation of diolefins by reacting the hydrocarbon mixture with hydrocyanic acid in the presence of a catalyst system, which contains nickel in zero oxidation state and an organophosphorous ligand; extraction of linear unsaturated nitriles from the reaction mixture with formation of a first stream PN1; second hydrocyanation of the PN1 stream in the presence of hydrocyanic acid and a catalyst system, which contains nickel in zero oxidation state, an organophosphorous ligand and a Lewis acid; extraction of unreacted unsaturated nitriles from the reaction mixture through distillation, with formation of a second stream PN2; extraction of formed dinitriles from the catalyst system through liquid/liquid extraction with a hydrocarbon solvent, which allows for extracting an organometallic complex, with formation of a first stream of dinitriles DN1; simultaneous delivery of streams PN2 and DN1 to the distillation stage to obtain a first run F1, which contains the said solvent, and a last run Q1, which contains dinitrile compounds and unsaturated nitriles; delivering the last run Q1 to the second distillation stage to separate unsaturated nitriles, which form a first run F2, from dinitriles which form a last run Q2; taking the last run Q2 to the third distillation stage to obtain a fraction which contains adiponitrile.
EFFECT: method involves a sequence of stages for separating different compounds, which eliminates by-products, such as alkyne trimerisation products which are contained in the C4 fraction, and prevents their accumulation in hydrocyanation reactors.
4 cl, 1 dwg
