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Commercial inorganic membranes

The separation efficiency (e.g. permselectivity and permeability) of inorganic membranes depends, to a large extent, on the microstructural features of the membrane/support composites such as pore size and its distribution, pore shape, porosity and tortuosity. The microstructures (as a result of the various preparation methods and the processing conditions discussed in Chapter 2) and the membrane/support geometry will be described in some detail, particularly for commercial inorganic membranes. Other material-related membrane properties will be taken into consideration for specific separation applications. For example, the issues of chemical resistance and surface interaction of the membrane material and the physical nature of the module packing materials in relation to the membranes will be addressed. [Pg.64]

Despite the fact that inorganic membranes are, in general, more stable mechanically than organic membranes, available mechanical properties data for commercial inorganic membranes are sketchy and these are not yet standardized for comparing various membranes. It appears that the methods used for obtaining various mechanical strength data are based on those for solid (nonporous) bodies and most of them arc listed as ASTM procedures. [Pg.87]

Tabulated in Table 3.3 are the various mechanical properties taken from product brochures of commercial inorganic membranes. The table is not intended for comparing different membranes as the reported data may not be obtained under similar test conditions. However, it is expected to give at least... [Pg.87]

The structural elements of commercial inorganic membranes exist in three major geometries disk, tube or tube bundle, and multichannel or honeycomb monolith. The disks are primarily used in laboratories where small-scale separation or purification needs arise and the membrane filtration is often performed in the flow-through mode. The majority of industrial applications require large filtration areas (20 to over 200m ) and, therefore, the tube/tube bundle and the multichannel monolithic forms, particularly the latter, predominate. They are almost exclusively operated in the cross-flow mode. [Pg.88]

The above early commercial developments of inorganic membranes, although slow at the beginning, have stimulated sufficient market interest to entice more companies to enter the field with new types of membranes. These activities and various features of currently available commercial inorganic membranes will be highlighted in Chapter 5. [Pg.21]

There are a variety of porous inorganic membranes in the market today. Highlighted in Table 5.1 are selected major commercial inorganic membranes according to their material type. So far the most widely used inorganic membranes are alumina membranes, followed by zirconia membranes. Porous glass and metal (such as stainless steel and silver) membranes have also begun to attract attention. [Pg.149]

When using commercial inorganic membranes for separation or membrane reactor applications at relatively high temperatures, say, greater than 400°C or so, care should be taken to assess their thermal or hydrothermal stability under the application conditions. This is particularly relevant for small pore membranes because they are often made at a temperature not far from 400 C. Even if such an exposure does not yield any phase changes, there may be particle coarsening (and consequently pore growth) involved. [Pg.375]

Thermal shock resistance. Temperature swing as part of the normal cycles of operation or regeneration of the membranes or membrane reactors can lead to deleterious thermal shock. The materials for the various components in a membrane reactor should be carefully selected to impart good thermal sh k resistance. This is particularly important for high temperature reactions. Also listed in Table 9.5 is a summary of various membrane materials along with qualitative description of their resistance to thermal shock. Again, the available data apply to dense materials. While various metal oxides have been made into commercial inorganic membranes, they tend to be affected by thermal shock much more than other ceramic materials. [Pg.382]

Most of the commercial inorganic membranes are not perfect membranes and have finite values of the permselectivity. Therefore, most of the reaction components permeate... [Pg.529]

Current commercial inorganic membranes come in a limited number of shapes disk, tube and monolithic honeycomb. Compared to other shapes such as spiral-wound and hollow-fiber that are available to commercial organic membranes, these types of membrane elements have lower packing densities and, therefore, lower throughput per unit volume of membrane element or system. [Pg.578]

Commercialized inorganic membranes exist in three configurations disks or sheets, tubes and multichannels/honeycombs. Usually, flat disks or sheets are limited to small scale industrial, medical and laboratory applications. They are used almost exclusively in flow-through filtration in contrast to cross-flow filtration in tubes and multichannel monoliths. Meanwhile, tubes and monoliths are used for various industrial applications [2, 4]. [Pg.301]

It is clear from the above discussion, carbon membrane still requires much improvement and a long journey to go through before it will become a dominant commercialized inorganic membrane in this century. However, caibon membrane has a great potential to replace other inoiganic membranes in the market because it has a number of unique characteristics and is able to separate gas mixtures, which have similar size of gas molecules, efficiently. [Pg.301]

Templation involves the use of a master with desired features, replication of the features (Figure 17.13) by molding and subsequent lifting off the replica or dissolution of the templates. Templation is useful for the preparation of polymeric superhydrophobic coatings. Many materials can be used as a template ranging from natural lotus leaves [75], a master prepared by lithographic processes, to commercial inorganic membranes. [Pg.399]


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