Experimental measurement of propane and propylene absorption in NMP/AgNO3 solvent

To enhance olefin/paraffin separation by absorption process, different ionic salts are used to react with olefin while they are not able to react with the paraffin. In this study, experiments were performed to measure the equilibrium solubility of propane and propylene in N-methyl pyrrolidone (NMP) containing silver nitrate (AgNO3) salt. Batch wise absorption experiments were performed at different temperatures (276 K, 293 K, and 328 K), different pressures up to 8.3 bar, and different salt concentrations (5 g/l and 10 g/l). The results showed that the solubility of propane and propylene in pure NMP and NMP containing silver ion increases with increasing pressure and decreasing temperature. Furthermore, the solubility of propane and propylene increases with the addition of silver nitrate salt into the solvent while the solubility of propylene is also greater than that of propane at the same operating conditions. The ratio of propylene to propane solubility at T = 293 K and 5 g/l and 10 g/l silver nitrate concentration was 1.30 and 1.48, respectively. Therefore, NMP containing silver nitrate salt is a suitable solvent for propylene/propane separation.