Final Report: Low-Cost Zeolite Membrane Modules for Solvent DehydrationEPA Contract Number: 68D03013
Title: Low-Cost Zeolite Membrane Modules for Solvent Dehydration
Investigators: Higgins, Richard J.
Small Business: CeraMem Corporation
EPA Contact: Manager, SBIR Program
Project Period: April 1, 2003 through September 1, 2003
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2003) RFA Text | Recipients Lists
Research Category: Nanotechnology , SBIR - Nanotechnology , Small Business Innovation Research (SBIR)
The goal of this Phase I research project was to demonstrate the technical feasibility of fabricating fully inorganic pervaporation membrane modules that, when scaled up, would combine state-of-the-art separation capabilities for dewatering solvents with costs low enough to provide an economic driver for industrial adoption of the technology. The pervaporation membrane modules combine a sodium A (NaA or 4A) zeolite membrane with a ceramic multichannel monolithic support configuration. The primary technical goal of this research project was to demonstrate that the zeolite membranes could be applied to small membrane "coupons" of the monolithic geometry, and that the resulting membrane modules exhibited desirable separation properties for dewatering of near-azeotropic solutions of alcohol and water.
The potential applications for these pervaporation membrane modules, if successfully scaled up to larger module sizes and commercialized, include dewatering of solvents at a large scale in industrial chemical manufacturing, pharmaceutical manufacturing, semiconductor manufacturing, and biotechnology industries. For the users, the main driving force for adoption of the technology would be lowered capital costs (compared with alternative pervaporation membrane systems), superior separation performance, and environmental/energy utilization characteristics (compared with nonmembrane separations used for dewatering, such as tertiary distillation or absorption with molecular sieves).
Experimental tasks carried out by the CeraMem Corporation during this Phase I research project were as follows: (1) fabrication of microfiltration (MF) membranes on porous silicon carbide (SiC) monolith coupons; (2) development of synthesis procedures for sodium A zeolite membranes applied on the MF-coated coupons, including characterization tests primarily aimed at detecting flaws in the zeolite membranes; and (3) testing of qualified zeolite membrane modules for pervaporative separation of near-azeotropic solutions of water and alcohol. MF membrane fabrication was routine and based on procedures previously developed by the contractor. The primary focus of the research project was development of specific procedures to produce high-quality sodium A zeolite membranes on the multichannel monolith supports. Special procedures were developed to enable the application of the membranes to the supports. Although resource limitations did not permit optimization of synthesis procedures, the best membranes developed during Phase I exhibited selectivities for water over isopropanol in excess of 1,000. Water flux levels approached 1 kg/m2-hr at 75°C when measures were taken to reduce permeate-side pressure drop restrictions within the modules.
This Phase I research project was successful in demonstrating all of the specific technical goals. Accomplishments include:
· Small monolithic coupons of the same material and flow configuration envisioned for ultimate full-scale products were successfully coated with sodium A zeolite membranes having desirable physical characteristics.
· In experiments of relatively brief duration, it was demonstrated that a monolith-based sodium A zeolite membrane module coupon had selectivities for water removal from a near-azeotropic alcohol-water feed solution that was similar to other zeolite membranes. It also was shown that, although the permeate fluxes obtained in these tests were lower than those for similar nonmonolith-supported membranes, the permeate flux limitations were attributed to permeate-side flow resistances that can be mitigated significantly using: (1) the "permeate conduits" that will be part of larger modules, and (2) larger pore size support materials.
· The sodium A membranes did not significantly deteriorate from run to run because of mechanical degradation.