Dynamic membranes commercial developments

Some of those developments at Oak Ridge were believed to spin off in some form at Union Carbide and some aspects of the efforts led to the commercialization of dyiuunically formed membranes primarily for ultrafiltration and hypeiTiltration (reverse osmosis) applications. In these dynamic membranes, a mixture of zirconium hydroxide and polyacrylic acid deposited on a porous support which provides the necessary mechanical strength. The support is mostly made of porous carbon although porous ceramic and stainless steel are also used. These non-sintered membranes, in great contrast to most of the membranes discussed in this book, are formed in situ and require periodic regeneration with new zirconium hydroxide and polyacrylic acid. 

Dynamic membranes originated in the research at the Oak Ridge National Laboratory in the 196O s. Development has produced commercial ultrafiltration and hyperfiltration membranes for industrial separation applications. Research continues in several laboratories to improve the selectivity and productivity of the membranes and to tailor them for specific applications. The development of dynamic membranes and current research is reviewed briefly. Research on polyelectrolyte blend membranes is described in detail as a representative method for tailoring dynamic membranes. 

This paper reviews some recent developments in dynamic membrane research, describes properties and applications of commercial membranes, and reports properties of dynamic polyblend membranes. Formation of Dynamic Membranes... 

A new supercritical fluid process has been developed for the continuous extraction of liquids. The most useful solvent employed in the recently patented process is supercritical or near-critical carbon dioxide(l). At the heart of the process are porous membranes. Their porosity combined with a near-critical fluid s high diffusivity create a dynamic non-dispersive contact between solvent and feed liquid. The technique is dubbed porocritical fluid extraction and will be commercialized as the Porocrit Process. 

The evaluation of the commercial potential of ceramic porous membranes requires improved characterization of the membrane microstructure and a better understanding of the relationship between the microstructural characteristics of the membranes and the mechanisms of separation. To this end, a combination of characterization techniques should be used to obtain the best possible assessment of the pore structure and provide an input for the development of reliable models predicting the optimum conditions for maximum permeability and selectivity. The most established methods of obtaining structural information are based on the interaction of the porous material with fluids, in the static mode (vapor sorption, mercury penetration) or the dynamic mode (fluid flow measurements through the porous membrane). 

The 2" phase (2006-2009) R D activities undertake a SI process optimization and the performance tests of various chemical reactors selected for the SI cycle. The 2" phase research covers a dynamic code development for the SI process, a construction of a lab. scale( l 000 NL/h) SI process, and integrated operations of the process at prototypical pressures. On the other hand, conceptual and basic designs of a pilot scale( 100 Nm /li) SI process and its equipment will also be carried out according to the optimized process established from the theoretical evaluation using a commercial-base computer code and the experiences of the lab. scale construction and operations. Preliminary performance tests of the equipment, mechanical devices, and accessories for the pilot scale SI process should be carried out to obtain the design basis. Not only the several catalysts based on non-noble metals required for section II in the SI cycle but also a membrane for the separation of the hydrogen required for section III will be developed during the 2" phase research period. 

In the absence of any mass-transfer resistance induced by the porous membrane, the continuous sweep of products in the gaseous phase effected a shift in thermodynamic equilibrium towards formation of alcohol. This was also demonstrated by the authors by introducing a convective mass transfer to the batch reaction model. In fact, a dynamic model of the reactor was also developed, and the results of simulations compared favorably with experiment and the performance of a commercially operated conventional reactor. 

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