Browsing by Author "Kapteijn, Freek"
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- Zeolite Beta Membranes for the Octane Upgrading of C5/C6 Light NaphtaPublication . Silva, José A.C.; Rodrigues, Alírio; Bárcia, Patrick da Silva; Ferreira, Alexandre; Gascon, Jorge; Aguado, Sónia; Kapteijn, FreekThe zeolite Beta membranes were prepared by secondary growth method in asymmetric tubular Al2O3 supports (Inocermic GmbH, Germany), combining three different types of seeding techniques and crystallization conditions. Figure 1 show SEM micrographs of a typical non-calcined beta membrane synthesized in this work (cross section view). The vapour permeation experiments performed in the apparatus shown in Figure 2 with mixtures of nHEX, 3MP, 23DMB and 22DMB show that permeate flux increase as the degree of branching decreases following the order: nHEX>>3MP>23DMB>22DMB. Approximately one third of the feed stream cross the membranes. Figure 3 shows that in the retentate stream the fractions of monobranched and normal hexane isomers (low RON compounds) decrease while the concentration of dibranched isomers (high RON compounds) is increased in relation to the equimolar feed composition. Consequently, the RON can be boosted in retentate up to 3.8 points. These results demonstrate the potential of the zeolite beta membranes for application in the production of additive-free premium gasoline.
- Zeolite Beta membranes for the separation of hexane isomersPublication . Bárcia, Patrick da Silva; Silva, José A.C.; Gascon, Jorge; Aguado, Sónia; Ferreira, Alexandre; Rodrigues, Alírio; Kapteijn, FreekThe preparation of a-alumina supported zeolite Beta membranes was successfully achieved and sped up by exploring combinations of three seeding techniques and three synthetic methods. The surface of the membranes was completely covered by well intergrown crystals; the thickness of the zeolite layers ranged from 2 to 6 lm depending on the synthesis method used. The quality of the membranes was tested by means of pervaporation of ethanol/1,3,5-triisopropylbenzene (TIPB) mixtures together with permporometry experiments. The performance in the vapour separation of quaternary equimolar mixtures of nhexane (nHEX), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB) and 2,2-dimethylbutane (22DMB) in the range 343–443 K showed that permeate flux decreases as the branching degree increases following the order: nHEX 3MP > 23DMB > 22DMB. In the retentate, the fractions of monobranched and normal hexane decrease while the concentration of dibranched isomers is increased compared to the feed composition. The influence of the temperature in the permeation fluxes indicates the existence of an activated transport mechanism which favours the permeation of more nHEX and 3MP with regard to their dibranched isomers. The octane number (ON) of the quaternary mixture was enhanced up to 5 points with the best synthesized membrane.