High temperature membranes

Staudt, R. and J. Boyer, Development of polybenzimidazole-based, high temperature membrane and electrode assemblies for stationary and automotive applications, U.S. DOE 2004 Annual Program Review Proceedings, Philadelphia, PA, May 2004. 

Another example of the high-temperature membrane technologies is a dual-phase membrane developed at Columbia University, which consists of solid oxide and molten carbonate. This membrane technology takes advantage of oxide and carbonate ionic transport. At the face of the membrane exposed to the high concentration of COz, carbonation dioxide... 

Rejection of sodium sulphate was exceptional at the lower temperatures but permeate recovery was low. The testing at 81°C fulfilled Kvaerner s need to reduce overall skid costs and provide good rejection with an acceptable recovery rate. The use of high temperature membranes has provided the means to optimise the number of membrane elements, reduce the equipment costs and ensure that the SRS skid is an economically attractive package. 

Table 11.1 High-temperature membranes effect of temperature on recovery and rejection. 

The development of high temperature membranes for hydrogen separation. 

PEM high temperature membrane, low catalyst loading, high performance MEA. 

Commercial applications have been identified primarily in the electronics industry where requirements for dimensional stability, mechanical properties, and high temperature resistance make these systems attractive in advanced circuit board technology. Other commercial applications include high temperature membranes and filters where these materials offer performance improvements over glass, Kevlar, and graphite composites. Industrial development of these types of materials will most likely be dependent on monomer cost and advances in various product properties requirements. 

Operation with low relative humidity of the gases at the stack inlet is preferred because it simplifies the system (humidification of reactant gases and water recovery). PEM fuel cells are operational even at room temperature, but the typical operating temperature is between 60°C and 80°C. In order to reduce the size of the heat rejection equipment there is a lot of reserch and development (R D) on high temperature membranes that would allow operation at 130-140°C. 

Bredesen, R., Jordal, K. and Bolland, O. (2004) High-temperature membranes in power generation with CO, capture. Journal of Membrane Science, 43, 1129-1158. 

High temperature membrane reactors for dean productions. Clean Products and Processes, 2, 179—186. 

The goal of the present study is the development of a high temperature membrane reactor for steam reforming of natural gas (methane), which occurs by the following reaction ... 

The membrane tubes must be sealed, possibly to each other and to the collector plate of the reactor vessel. The sealing has to be adherent and mechanically strong but also gas-tight and thermally resistant, up to temperatures of at least 700°C. These high demands make sealing one of the most important problems in current high temperature membrane technology. 

G Saraco, G F Versteeg, W P M van Swaaij, Current hurdles to the success of high-temperature membrane reactors , J Membr Sci, 1994, 95, 105-123... 

High temperature membranes, that can operate at temperatures above 100 °C, are desirable to promote heat rejection, speed up electrode reaction rates, and to improve tolerance to impurities. This is an active area of materials research. Unfortunately, space constraints preclude a detailed description of fuel cell technologies and the underlying issues. Instead, the reader is referred to excellent reviews and books that exist on this topic.45 47... 

Wainright, J.S., Litt, M.H., and Savinell, R.E., High-temperature membranes, in Handbook of Fuel Cells Eundamentals, Technology, and Applications, 1st ed., Vielstich, W., Lamm, A., and Gasteiger, H.A., Eds., John Wiley Sons, West Sussex, England, 2003, p. 436. 

Ilias and Govind(lO) have reviewed the development of high temperature membranes lor membrane reactor application. Hsieh(4) has summarized the technology in the area of important inorganic membranes, the thermal and mechanical stabilities of these membranes, selective permeabilities, catalyst impregnation, membrane/reaction considerations, reactor configuration, and reaction coupling. 

Winnick, J., 1990, High temperature membranes for H2S and SO2 separations, DOE Quarterly Progress Report DOE/PC/90293-T1. 

The combination of high temperature and chemical exposure poses a very challenging material problem that is quite common in high-temperature membrane reactor applications. The consequence of structural degradation as a result of such a combination not only affects the permeability and permselectivity but also leads to physical integrity or mechanical properties. These issues apply to both metal and ceramic membranes. 

A major drawback of surface diffusion for high-temperature membrane reactor application lies in the fact that adsorptive bonds l>etween molecules and surfaces become less and less strong as long as temperature increases, thus lowering the separation factors achievable. 

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