Effects of Ligand Structure on Reactive Vapor−Liquid Distribution Ratio and Selectivity for C6-Olefin Isomers

Abstract

Vapor−liquid equilibrium experiments are performed to evaluate the suitability of π-complexing silver of various phosphoric and sulfonic acids for application as functionalized solvents in Reactive Extractive Distillation to separate 1-hexene from other C6-olefin isomers. The effect of solvent structure is investigated by testing five different ligands, di (2-ethylhexyl) phosphoric acid (D2EHPA), di (butyl) phosphoric acid (DBPA), mono (2-ethylhexyl) phosphoric acid (MEHPA), di (nonyl) naphthalene sulfonic acid (DNNSA), and dodecyl benzene sulfonic acid (DBSA), for a variety of C6-olefin isomers (1-hexene, 2-methyl-1-pentene, n-hexane, 1,5-hexadiene, trans-2-hexene). The introduction of silver in the solvent increases the solvent selectivity for 1-hexene. At equal silver concentration the ligand size does not influence the selectivity of chemically similar components (1-hexene/2-methyl-1-pentene) but increases that of chemically different components (1-hexene/n-hexane). A lower pressure, a higher silver concentration, or higher solvent-to-feed (S/F) ratio are beneficial for the 1-hexene selectivity. The highest selectivity is obtained for Ag−DBPA (20 wt % Ag, S/F-ratio of 3): 1.23 for 2-methyl-1-pentene and 1.42 for n-hexane, relative to 1.04−1.06 for unreactive solvents.