Fabrication of High-quality NaA Zeolite Membranes with a Novel Plate & Frame Configuration for Molecular-scale Mixture Separations

Bioethanol has come into widespread use as fuel additives worldwide, especially in the U.S. and Brazil, aiming to mitigate CO2 emissions by up to 70% and sustain the carbon-neutral ecosystem. Generally, bioethanol in various fermentation broths has a maximum concentration of 6-8 wt.%. Hence, concentration of bioethanol from dilute streams poses a grand challenge from the standpoint of energy efficiency. In bioethanol dehydration processes, the conventional distillation process is adopted, followed by energy-intensive pressure swing adsorption (PSA) dehydration process. Many bioethanol plants in the U.S. ran the PSA process more than 10 years ago, and will require adsorbent bed retrofitting in next several years. Energy-efficient membrane separation technologies are considered a highly cost-competitive alternative to PSA process for bioethanol concentration & purification. However, in order for these membrane technologies to become incorporated into real world applications, focused R&D needs to be conducted in order to increase the technical feasibility and to lower the cost of implementation. In this proposal, nGimat will make great endeavors to fabricate a new class of high quality NaA zeolite membranes for energy efficiency applications, e.g., energy-saving recovery of bio- chemicals or biofuels from a wide range of fermentation broths. It is anticipated that the production cost of these zeolite membranes will be at least 50% lower than zeolite membranes available nowadays, and will play a critical role in reaching the cost objective of $0.02-0.09/L of bioethanol isolated from fermentation broths, thereby enabling membranes for energy-efficient applications. Development of such low-cost NaA zeolite membranes will require distinct innovations in substrate formulation and membrane configuration design to outperform best-in-class commercially available membranes. During Phase I, nGimat will (1) develop NaA zeolite crystal seeded metallic plates with big pores and high porosity (≥90%) as substrates for formulating well-intergrown hierarchically-structured zeolite membranes; and (2) assemble membrane elements in the fashion of a plate & frame configuration to achieve comparable packing density in comparison with commonly used tubular-type membrane modules. It is expected that our newly designed zeolite membranes will enable the manufacture of high-quality zeolite membranes in an economical yet reproducible way. Overall, key improvements pursued in this effort will be reflected by overcoming prohibitively high production cost of these membranes, and by a significant energy saving of about 20-40%, as compared to conventional separation technologies such as distillations. Phase II of this SBIR effort will be concentrated on further optimization and scale-up production of the best-performing NaA zeolite membranes to meet the demands of energy efficiency.