Inorganic membranes applications

R. R. Bhave, Inorganic Membranes Synthesis, Characteristics and Applications, Van Nostrand Reinhold, New York, 1991. 

The ceramic membrane has a great potential and market. It represents a distinct class of inorganic membrane. In particular, metallic coated membranes have many industrial applications. The potential of ceramic membranes in separation, filtration and catalytic reactions has favoured research on synthesis, characterisation and property improvement of inorganic membranes because of their unique features compared with other types of membrane. Much attention has focused on inorganic membranes, which are superior to organic ones in thermal, chemical and mechanical stability and resistance to microbial degradation. 

The vast increase in the application of membranes has expanded our knowledge of fabrication of various types of membrane, such as organic and inorganic membranes. The inorganic membrane is frequently called a ceramic membrane. To fulfil the need of the market, ceramic membranes represent a distinct class of inorganic membrane. There are a few important parameters involved in ceramic membrane materials, in terms of porous structure, chemical composition and shape of the filter in use. In this research, zirconia-coated y-alumina membranes have been developed using the sol-gel technique. 

In this chapter, we Hmit ourselves to the topic of zeolite membranes in catalysis. Many types of membranes exist and each membrane has its specific field where it can be appHed best. Comparing polymeric and inorganic membranes reveals that for harsher conditions and high-temperature applications, inorganic membranes outperform polymeric membranes. In the field of heterogeneous catalYsis, elevated temperatures are quite common and therefore this is a field in which inorganic membranes could find excellent applications. 

Guizard, C., Bac, A., Barboiu, M. and Hovnanian, N. (2001) Hybrid organic-inorganic membranes with specific transport properties. Applications in separation and sensors technologies. Separation and Purification Technology, 25, 167-180. 

In Table 4.3, a selection of inorganic membrane suppliers is given. Very little data are available on applications in catalysis so far. The membranes can be used for separation in the ultra- or nanofiltration range. 

Bhave, R. 1991. Inorganic membranes Synthesis, characteristics and applications, 95-107, 129-54. New York Van Nostrand Reinhold. 

In the recent years, many researchers have devoted attention to the development of membrane science and technology. Different important types of membranes, such as these for nanofiltration, ultrafiltration, microfiltration, separation of gases and inorganic membranes, facilitated or liquid membranes, catalytic and conducting membranes, and their applications and processes, such as wastewater purification and bio-processing have been developed [303], In fact, almost 40 % of the sales from membrane production market are for purifying wastewaters. 

All major industrial participants in the developments that took place in the period 1980-1985, were companies which actively participated in the development and manufacture of inorganic membranes for nuclear applications. 

This concept later evolved into the Ucarsep membrane made of a layer of nonsintered ceramic oxide (including Zr02) deposited on a porous carbon or ceramic support, which was patented by Union Carbide in 1973 (Trulson and Litz 1973). Apparently, the prospects for a significant industrial development of these membranes were at the time rather limited. In 1978, Union Carbide sold to SPEC the worldwide licence for these membranes, except for a number of applications in the textile industry in the U.S. At that time, SPEC recognized the potential of inorganic membranes, but declassification of the inorganic membrane technology it had itself developed for uranium enrichment was not possible. 

Since membranes no longer had important nuclear applications in future, SPEC was sold in 1987 by the CEA to the French company Rhone-Poulenc which merged them with their polymeric membrane division to form the new subsidiary, currently known as Tech Sep. Zr02 based ultrafiltration membranes on 6 mm inner-diameter carbon tubes continues to be the main product line of Tech Sep in terms of inorganic membranes. 

In summary, the development of inorganic membranes was initially oriented towards uranium enrichment which is still by very far their most significant application. Some of the key participants involved in the nuclear programs further developed them into cross-flow filtration membranes. The recent years have seen the start of a much broader exploration of the manyfold potentialities of inorganic membranes, both in terms of materials and applications. Thus, a multifaceted new field of technology is emerging. 

INORGANIC MEMBRANES SYNTHESIS AND APPLICATIONS Table 2.3. Advantages and Disadvantages of Inorganic (Ceramic) Membranes... 

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