http://www.cnr.it/ontology/cnr/individuo/prodotto/ID313542
Synthesis and Applications of Zeolite Membranes (Comunicazione a convegno)
- Type
- Label
- Synthesis and Applications of Zeolite Membranes (Comunicazione a convegno) (literal)
- Anno
- 2013-01-01T00:00:00+01:00 (literal)
- Alternative label
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- National Research Council Institute for Membrane Technology (ITM-CNR)
c/o The University of Calabria, cubo 17C, Via Pietro BUCCI, 87036 Rende CS, Italy (literal)
- Titolo
- Synthesis and Applications of Zeolite Membranes (literal)
- Abstract
- Membrane separations using zeolite might offer great opportunities to reduce energy demands in chemical and petroleum industries. For their high thermal and chemical stability they can be used when polymeric membranes cannot operate. Although the enormous efforts made to improve the quality of these membranes, their application at industrial scale is confined to T and NaA zeolites for organic solvent dehydration by means of pervaporation and vapour permeation processes [1]. The commercial zeolitic membranes cannot yet be employed in gas separations for the presence into the zeolite layer of intercrystalline defects. This problem, with other disadvantages such as reproducibility problems in the preparation step [2] and the cost of the support [3] strongly limited their wide application at industrial level. For overcoming these problems different methods for their preparation have been developed, including the in situ and the secondary growth methods. The secondary growth [4] method presents two steps: seeding and growth. The separation of the nucleation from the crystal growth gives the possibility to optimize the conditions of each state independently. In this method very critical step is the seeding. A new seeding procedure was designed and used to achieve the selective zeolitic layer on the inner tubular support surface [5] more reproducible than those present in the open literature.
Zeolite membranes have been also studied as catalytic membrane reactors for the carbon monoxide selective oxidation (Selox) from hydrogen rich gas streams [6, 7]. The catalytic membranes reduced the amount of CO from 10,000 ppm down to 10-50 ppm, depending on the operating conditions. These results confirm the good potentiality of catalytic zeolite membranes for a deep purification of H2-rich streams and with the possibility to use the hydrogen for the fuel cell applications.
Recently, it was also demonstrated the possibility to produce the L-3,4-dihydroxyphenylalanine (L-DOPA) using an innovative route based on the immobilization of mushroom tyrosinase on the inner surface of the zeolite membrane [8]. This approach combines the active role of the zeolite membrane in supporting the enzyme and for blocking free radicals generated during the reaction. The biocatalytic zeolite membranes exhibited good performance in terms of specific activity and productivity [8]. In fact, comparing the performance of the enzyme free in solution and immobilized on zeolite membrane, it can be observed that its specific activity in the latter case is 2.76 times higher than the first one (1.93 ?mol mg-1 min-1 and 0.70 ?mol mg-1 min-1, respectively). It is higher than the values present in the open literature.
Mixed matrix membranes represent an interesting concept to combine the advantages typical of different porous materials (such as zeolites, carbon and so on) with the established processing of organic polymers as membranes. For example the application of mixed matrix membranes (zeolite loaded) in controlled drug release has been studied for the release of the ibuprofen from polydimethylsiloxane-based membranes. The obtained results indicate as PDMS-NaX membranes are promising as transdermal drug delivery devices [9]. (literal)
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