(182e) High Surface Area Zeolite Membrane for Efficient Bio-Fuel Production

Distillation and adsorption has been commonly used for respective enrichment and polishing of ethanol fuels in today’s ethanol plants. In this presentation, development of thin zeolite/metal sheet membranes of surface area packing density comparable to polymeric sheets is discussed to enhance ethanol dehydration energy efficiency and lower capital costs. The mechanical structural integrity of this new membrane product concept is substantiated with stress modeling. A relatively simple fabrication process that renders its low-cost manufacturing is delineated with experimental results. Separation process studies are conducted along with the membrane product development, which include (i) performance tests with real-world feeds and (ii) process design and simulation of membrane separation integrated with whole plants. The present membrane is highly permeable to water that significant one-pass dehydration can be obtained within a short residence time (seconds).  However, the membrane performance can be drastically affected by the feedstock. Proper pre-treatment is necessary to achieve stable separation performances with the real-world feed. Based on experimental results, a two-stage membrane separation system is proposed to conduct ethanol enrichment and purification by replacing respective distillation and adsorption processes. More than 90% energy saving is shown using the membrane separation. Due to high permeance and high membrane area packing density, the membrane module estimated for a 40-million gal/year ethanol plant can be fairly compact, about the size of plate heat exchangers. This membrane technology is promising for retrofitting of existing corn ethanol plants and for building of new cellulosic ethanol plants in the future as well.