ECN publication
Inorganic membranes for pervaporation: proof of concept
Published by: Publication date:
ECN Energy Efficiency in Industry 1-6-2004
ECN report number: Document type:
ECN-C--04-106 ECN publication
Number of pages: Full text:
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The aim of the here described project was to develop membranes, modules and systems to come to a quick implementation of tubular inorganic membranes in dewatering pervaporation processes in the process industry as a cost effective and energy efficient alternative for e.g. distillation.

Based upon commercially available ceramic support tubes microporous silica membranes for pervaporation have been made using fully automatic techniques on a commercial scale. The production facility has been designed for an output of 12,000 tubes (or about 500 m2) annually. Dehydration of several organic mixtures using these membranes has been performed from lab scale up to a scale of 1 m2 of membrane area and shows good selectivities and fluxes that are much higher than for polymeric membranes. Process calculations for some processes show high energy savings and favourable economics.

The silica membranes however show flux decline in time (at an almost constant selectivity) and the membrane performance has been improved by incorporating methyl groups into the silica structure. This methylated silica membrane now meets the long term flux demands as needed in industrial processes. As the silica based membrane shows a structural reorganisation at temperatures above 100oC, the use is at this moment limited to this temperature. Membrane fouling due to salts in the feed mixture in combination with membrane cleaning is a topic for further research.

An isothermal module for the inorganic pervaporation membranes has been developed and optimised by chemical engineering and computational fluid dynamics calculations towards heat transfer and pressure drop. Also costs for membrane systems have been optimised by smart module arrangements in a pervaporation set-up. Modules up to 5 m2 and designs for larger scale modules have been made.

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