Zeolites solvent transport

Furthermore the influence of acetone as a solvent was examined. For the homogeneously catalyzed epoxidation reaction in general, lower yields and selectivities are obtained with acetone as solvent. However for the transport of substrates and oxidant in and out of the zeolite channels, acetone could have a beneficial effect. This could not be confirmed by our experiments. 

The solvent seems to favor diffusion and transport processes in the zeolite channels, the activation of the reactants is due to confinement catalysis. 

Shah et al. (2000) used hydrophilic zeolite NaA membranes for the separation of alcohol-water, methanol-water, EtOH-water, IPA-water, and DMF-water mixtures. The total flux for EtOH-water mixture was found to vary from 2 to 0.05 kg/m h at 60°C as the feed solvent concentration was increased from 0 to 100 wt%. The total fluxes for methanol-water and IPA-water mixtures were observed to vary from 2 to 0.15 and 2 to 0.21 kg/m h, respectively, as the alcohol concentration was changed from 0 to 100 wt%. Both water-to-EtOH and water-to-IPA separation factors were observed to lie between 1000 and 5000 over a wide range of solvent concentrations. The water-to-methanol separation factor was found to lie in the range of 500-1000. It was observed that ionic Na+ sites in the NaA zeolite matrix play a very important role in the water transport through the membrane. These sites act both as water sorption and transport sites. 

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