Separation of Butanes and Butylenes by Extractive Distillation with MEK/NFM Mixed Solvent

The feasibility of methyl-ethyl-ketone (MEK) and N-formylmorpholine (NFM) as combination solvent for separation of butanes and butylenes by extractive distillation was investigated. Based on the thermodynamic studies and laboratory data, five butylenes-enriching plants of 30,000 t/a scale were established. The concentration of butylenes product were 97% (wt%), and the recovery of butylenes achieved was 90%. Antifoam agent was employed to prevent the solvent from foaming and worked effectively. As compared with NFM/MOR (morpholine) solvent system or DMF, MEK/NFM solvent system showed advantages such as low bottom temperature of strip column and low toxicity. Further comparison with ACN (acetonitrile) solvent system indicates that MEK/NFM system presented low residue in top production.