Separation of propyne, propadiene and propylene with carboxylate ionic liquids

Abstract

Separation of C3 gases including propyne, propadiene and propylene is important for propylene purification. The absorption separation technology using ionic liquid as the separation medium can overcome the shortcomings of traditional organic solvents and is expected to be promising to the separation of C3 gases. The solubilities of C3 gases in strongly hydrogen-bonding basic carboxylate ionic liquids (ILs) have been measured in this work, and the results showed that these ILs had both high capacity and high selectivity in the separation of C3 gases. In particular, [P4442][C5COO] had a molar solubility of 0.3 mol/mol for propyne at 313.1 K, which reached the highest value so far, meanwhile, the solubility of propadiene reached 0.14 mol/mol, significantly higher than that of propylene. The solubility of C3 gases in ILs with different anion lengths and different temperatures showed that the better C3 gases separation performance was achieved with a shorter anion and a lower temperature. Absorption-desorption recycling tests proved that these ILs had great recycling performance.