A comprehensive comparative study on morphology and pervaporative performance of porous-supported mesoporous zeolitic membranes

Abstract

Abstract Mordenite (MOR) and faujasite (FAU) were formed as a membrane layer on tubular mullite and disk-shaped α-alumina supports for pervaporation (PV) dehydration of ethanol (EtOH). Structural analyses were carried out using XRD, SEM and EDAX. EtOH/water PV process was utilized to assess the membranes performances. The experiments show the fairly high separation factor representing the defect-free membrane layer and legible nonzeolitic pores on the top-layer. The effects of synthesis parameters including ceramic support, repetition of coating, seeding method, crystallization time (14 and 18 h) and temperature (160, 170 and 180 °C), and Si/Al ratio of the precursor gel formulation (12 and 16) on the membranes structures and their PV performances were investigated. Furthermore, the effective operational conditions (feed concentration (50, 70 and 90 wt% EtOH) and temperature (25 and 45 °C), and vacuum on permeate side (80 and 130 mmHg)) on PV performance of the membranes were studied. According to a combined performance parameter, pervaporation separation index (PSI), the MOR layer on α-alumina (MOR_D-II) can be reported as the best membrane for EtOH/water PV process. Permeation flux (43.43%), separation factor (30.39%) and PSI (62.35%) decrease with increasing EtOH concentration in feed (50–90 wt%). However, increasing feed temperature increases permeation flux and decreases separation factor, whereas applying higher vacuum in the permeate side leads to the opposite trend.