Liquefied petroleum gas desulfurization by HTBN/PAN composite membrane

Hydroxyl-terminated polybutadiene/acrylonitrile (HTBN) polymer material was selected for deep desulfurization of liquefied petroleum gas (LPG) according to the solubility parameter method, and then crosslinked HTBN membranes were prepared, in which asymmetric polyacrylonitrile (PAN) membranes prepared with phase inversion method acted as the microporous supporting layer in the flat-plate composite membrane. The different function compositions of composite membranes were characterized by reflection FTIR in order to investigate the crosslinking reaction. The surface and section of composite membranes were investigated by scanning electron microscope (SEM). The composite membranes prepared in this study were used in LPG for deep desulfurization. Effects of amount of HTBN and operation pressure on the desulfurization efficiency of LPG were investigated experimentally. Experiment results demonstrated that with the membrane having a HTBN layer of 11 μm, permeability parameter of methyl mercaptan came to 17,002 Barrer and that of hydrocarbon came to 504 Barrer at 30 wt % of HTBN and 0.25 MPa, which showed that the membrane used to desulfurization in LPG can achieve high-removal efficiency. These results demonstrated that the membrane separation method could be significant in practical application for deep desulfurization of LPG.