Synthesis, Evaluation, Modeling and Simulation of Nanopore NaA Zeolite Membranes for Application in Ethanol Separation

Zeolite membranes have uniform and molecular-sized pores that separate molecules based on the differences in the molecules’ adsorption and diffusion properties. Strong electrostatic interaction between ionic sites and water molecules (due to its highly polar nature) makes the zeolite NaA membrane very hydrophilic. Zeolite NaA membranes are thus well suited for the separation of liquid-phase mixtures by pervaporation. In this study, experiments were conducted with various ethanol–water mixtures (1–20 wt. %) at 25 °C. Total flux for ethanol–water mixtures was found to vary from 0.331 to 0.229 kg/m2.h with increasing thanol concentration from 1 to 20 wt.%. Ionic sites of the NaA zeolite matrix play a very important role in water transport through the membrane. These sites act both as water sorption and transport sites. Surface diffusion of water occurs in an activated fashion through these sites. The precise Nano-porous structure of the zeolite cage helps in a partial molecular sieving of the large solvent molecules leading to high separation factors. A comparison between experimental flux and calculated flux using Stephan Maxwell (S.M.) correlation was made and a linear trend was found to exist for water flux through the membrane with ethanol concentration. A comprehensive model also was proposed for the ethanol-water pervaporation by Finite Element Method (FEM). The 2D model was masterfully capable of predicting water concentration distribution within both the membrane and the feed side of the pervaporation membrane module. Keywords: nanopores, pervaporation, ethanol separation, zeolite NaA membrane, FEM simulatio

CFD simulation of pervaporation of organic aqueous mixture through silicalite nano-pore zeolite membrane

Nanopore silicalite type membranes were prepared on the outer surface of a porous-mullite tube by in situ liquid phase hydrothermal synthesis. The hydrothermal crystallization was carried out under an autogenously pressure, at a static condition and temperature of 180 °C with tetrapropylammonium bromide (TPABr) as a template agent. The molar composition of the starting gel of silicalite zeolite membrane was: Na2O/SiO2=0.287-0.450, H2O/SiO2 = 8-15, TPABr/SiO2 = 0.01-0.04. The zeolites calcinations were carried out in air at 530 °C, to burn off the template (TPABr) within the zeolites. X-ray diffraction (XRD) patterns of the membranes consisted of peaks corresponding to the support and zeolite. The crystal species were characterized by XRD, and morphology of the supports subjected to crystallization was characterized by scanning electron microscopy (SEM). Performance of silicalite nanoporous membranes was studied for separation of water-unsymmetrical dimethylhydrazine (UDMH) mixtures using pervaporation (PV). Finally, a comprehensive steady state model was developed for the pervaporation of a water-UDMH mixture by COMSOL Multiphysics software version 5.2. The developed model was strongly capable of predicting the effect of various dimensional factors on concentration and velocity distribution within the membrane module. The best silicalite zeolite membranes had a water flux of 3.34 kg/m2.h at 27 °C. The best PV selectivity for Silicalite membranes obtained was 53

Preparation of Nano Pore ZSM-5 Membranes: Experimental, Modeling and Simulation

Nano pore ZSM-5type membranes were prepared on the outer surface of a porous-mullite tube by in situ liquid phase hydrothermal synthesis. The hydrothermal crystallization was carried out under an autogenous pressure, at a static condition and at a temperature of 180°C with tetra propyl ammonium bromide (TPABr) as a template agent. The molar composition of the starting gel of ZSM-5 zeolite membrane was: SiO2/Al2O3=100, Na2O/Al2O3=0.292, H2O/Al2O3=40–65, TPABr/ SiO2=0.02-0.05. The zeolites calcinations were carried out in the air at 530°C, to burn off the template (TPABr) within the zeolites. X-ray diffraction (XRD) patterns of the membranes consisted of peaks corresponding to the support and zeolite. The crystal species were characterized by XRD, and morphology of the supports subjected to crystallization was characterized by scanning electron microscopy (SEM). Performance of Nano-porous ZSM-5 membranes was studied for separation of water–unsymmetrical dimethylhydrazine (UDMH) mixtures using pervaporation (PV). Finally, a comprehensive unsteady-state model was developed for the pervaporation of water-UDMH mixture by COMSOL Multiphysics software version 5.2. The developed model was strongly capable of predicting the effect of various dimensional factors on concentration and velocity distributions within the membrane module. The best ZSM-5 zeolite membranes had a water flux of 2.22 kg/m2.h at 27°C. The best PV selectivity for ZSM-5 membranes was obtained to be 55