Zeolites separation

Adsorption in drying, purification and separation. Zeolites can absorb up to 25% of their weight in water. 

Hong, M., R.D. Noble, and J.L. Falconer, Highly selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications, Annual Technical Progress Report, U.S. DOE Contract DE-FG26-02NT41536, December 2005. 

ZeoHte adsorbents play a dominant role in purifications owing to their ability to both adsorb large quantities of material and to achieve extremely low mole fractions of these adsorbed these compounds in product gas. Zeolites are the preferred adsorbent types for dehydration to low levels, purification and in several bulk separations. Zeolites also are employed in a significant portion of the PSA hydrogen purification market segment where they add value to bulk separations by achieving particularly high purity specifications. 

Liquid Separation. Zeolites X and Y, in various ion-exchauged forms, are the substrates used iu the processes developed by UOP for separatiug liquid uuxtures (see Table 30). The hydrophobic nature of Y and its modified forms are used to scavenge organic molecules from aqueous enviromnents (e.g. halohydrocarbons). 

In type a., the separating zeolite layer is equipped with catalytic sites (Bronsted add sites, Lewis acid sites (cations, special Al-sites), metal clusters, catalytic complexes). In type b., the non-supported side of the zeolite layer serves as a support for catalytic entities, e.g. metal crystallites. In type c., zeolite crystals with catalytic power are embedded in a matrix, e.g. a polymer membrane. 

Okamotoetal. [193] studied several water/organic systems that are Usted in Table 11.5, and the performance of the zeolite A membrane was excellent for all the separations. These results could be also compared with the ones obtained using microporous silica manbranes [213]. Silica membranes, fora water/dioxane (10/90 wL%) mixture at 60°C, showed a separation factor of 125 and a water flux of 2.2 kg/(m h). In the case of DMF, the results obtained for a water/DMF mixture (13.2/86.8 wt.%) were 30 and 0.225 kg/(m h) for the separation factor and water flnx, respectively. In both separations, zeolite A ontperforms the microporous silica manbrane. 

H. Richter, Gas Separating Zeolite Membranes. Presentation at the Mem-brain summer school (Gas separation membranes for zero-emission fossil power plants), Aagen, Germany, 2008. 

N-Cyclohexyl pyrrolidone Sodium silicoaluminate gas separator Zeolite... 

Masuda, T., Fukumoto, N., Kitamiua, M., Mukai, S. R., Hashimoto, K., Tanaka, T., et al. (2001). Modification of pore size of MFI-type zeolite by catalytic cracking of silane and application to preparation of H2-separating zeolite membrane. Microporous atul Mesoporous Materials, 48, 239-245. 

Two types of sorbents have been examined for ethane/ethylene and propane/propylene separations zeolites/molecular sieves and r-complexation sorbents. The... 

Information on COS formation according to eq. (1) in the presence of sorbents is both scarce and contradictive. To chose selectively separating zeolites for gas desulphurization, one has to characterize and systematize their different technical and lab-synthesized modifications with regard to standard conditions. Particular static conditions for COS formation experiments were chosen to allow for a characterization and quantification of catalytic activities of the sorbents. 

Ceramic membranes have been studied for esteriflcation/condensation reaction, where one integrates reaction and separation. Zeolite is seen as an alternative in different processes, and this is put directly into the reaction mixtures to perform the separation. The maximum operating temperature could be a few hundred degrees centigrade, this being a function of the membrane material. 

---