Carbon molecular sieving membranes production process

Molecular sieve dryers, 10 613 Molecular-sieve effects, 16 821 Molecular sieve membranes, 15 813t Molecular sieve products commercial, 16 838-839t manufacturing processes for, 16 831 Molecular sieves, 16 811-853. See also Carbon molecular sieves Zeolite entries... 

Besides zeolites and traditional silica, carbon molecular sieves have been investigated as dispersed phases. Mixed-matrix membranes have been created using carbon molecular sieves dispersed in polyetherimide (Ultem) and Matrimid, separately. These mixed-matrix membranes displayed an increase in both permeability and selectivity over their neat polymer counterparts." The effect of trace amounts of toluene impurity in the feed stream of these carbon-polymer membranes was tested, and the membranes showed promising stability over time against the impurity. Zeolite-carbon mixed-matrix membranes have recently been developed where the carbonized polymer matrix is derived from a pure Matrimid membrane." These mixed-matrix membranes double the CO2/CH4 selectivity of the pure carbonized Matrimid membranes tested but lose over half of their productivity in the process. While these properties are well above Robeson s upper bound, other researchers have achieved better separation properties using only pure carbonized Matrimid membranes. ... 

A wide range and a number of purification steps are required to make available hydrogen/synthesis gas having the desired purity that depends on use. Technology is available in many forms and combinations for specific hydrogen purification requirements. Methods include physical and chemical treatments (solvent scmbbing) low temperature (cryogenic) systems adsorption on soHds, such as active carbon, metal oxides, and molecular sieves, and various membrane systems. Composition of the raw gas and the amount of impurities that can be tolerated in the product determine the selection of the most suitable process. 

SO /CH ) are common industrii gas separations that utilize membrane technology. MMMs have been developed for gas separation processes in which different types of polymers and rigid filler materials such as zeolite were used for the preparation [68-70]. Here, selectivity is achieved by a combination of permeation rates of the desired gas through the polymer and the filler material [67]. Molecular sieves were initially incorporated by dispersion of zeolites in rubber polymer [71]. Furthermore, the dispersion of zeolite in glassy polymers has been studied [72,73]. Carbon nanotubes have recently been used as dispersed materials in the production of MMMs for gas separation [73-76]. 

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