Propiedades ácidas de mordenitas modificadas por desaluminización
Resumen
Se estudia la desaluminización de la mordenita tratada hidro térmicamente. El aluminio extra-red ALER producido durante la desaluminización se encuentra bajo diferentes formas, una iónica en posición de intercambio, una neutra y y una fase amorfa invisible al RMN del 27Al. Los sitios ácidos de Lewis observados son asociados con la presencia de especies ALER en los canales de la mordenita. No se distingue una dependencia directa entre la fuerza de los sitios ácidos de Bronsted y el contenido en aluminio reticular ALR. Sin embargo, el número de los sitios ácidos titulados por la piridina aumenta luego de la desaluminización. los estudios de adsorción muestran la aparición de una red mesoporosa secundaria, la cual disminuye las restricciones difusionales al interior del grano.
Referencias bibliográficas
Beaumont, R. y Barthomeuf, D. , 1972. "X, Y, aluminium deficient and ultrastable faujasite-type zeolites. l. acidíc and structural properties" , J. of Cata!., 26: 218. https://doi.org/10.1016/0021-9517(72)90052-8
Beyer, H. K., Belenykaja, l. M., Mishin, I. W. y Borbely, G., 1984. "Structure and reactívity of modífied zeolítes". Amsterdam, Jacobs, P. et al. (Editors), Elsevier Science Publishers, 133 - 140. https://doi.org/10.1016/S0167-2991(09)61148-4
Bodart, P., Nagy, J. B., Debras, G., Gabelica, Z., y Jacobs, P., 1986. "Aluminum siting in mordenite and dealu mination machanism", J. Phys. Chem., 90 (21): 5183 - 5190. https://doi.org/10.1021/j100412a058
Chen, N.Y., Smith, F. A., 1976. "Preparation of dealu minized mordenite" , lnorganic Chemistl)', vol 15, No. 2, 295 - 297. https://doi.org/10.1021/ic50156a011
Coudurier, G., Naccache, C. y Védrine, J. C. , 1982. "Uses of IR spectroscopy in identifying ZSM zeolite structure", J. Chem. Soc., Chem. Commun., (24): 1413 - 1414. https://doi.org/10.1039/c39820001413
Engelhardt, _G. y Michel, D., 1987. Higlz Resolution Solid State NMR of silicates and Zeolites, John Wiley & m. .
Ga1nlon, G., Conna,.. A., y Fornés, V., 1989. "Evidence for the presence of superacid nonframework hydroxyl groups in dealuminated HY zeolites' '., Zeolites, 9 (1): 84 - 86. https://doi.org/10.1016/0144-2449(89)90015-8
Gnep, N. S., Roger, P., Cartraud, P., Guisnet, M., Juguin, B., y Hamon, C., 1989. C.R. Acad. Sci. Paris, t. 309, Serie II, 1743 - 1747.
Goovaerts, F., Vansant, E. F., Phílippaerts, J., Hulsters, P.D. y Gelan, J., 1989. "Jnitial cracking properties and physícochemical characterization of acid-leached small port (SP) and large-port (LP) mordenites by pulse he xane cracking, infrared and aluminum-27 magic angle spinning nuclear magnetic resonance spectroscopy", J. Chem. Soc., Faraday Trans. 1, 85 (11): 3675 - 3685. https://doi.org/10.1039/f19898503675
Goovaerts, f., Vansam, E. F., Hulsters, P. D. y Gelan, J., 1989. "Stmctural vibrations of acid-leached mordenites: determi nation of structural aluminum by wavenumber and intensity analysis", J. Chem. Soc., Faraday Trans., 1, 85 (11): 3687 - 3694. https://doi.org/10.1039/f19898503687
Gregg, S. J. y Sing, K. S. W., 1982. Adsorption, suiface area and porosity, Londres, Academic Press, 303 pp.
Haas, J., Fetting, F., Plog, C., Kerfin, W., Gerhard, W. y Roth, G., 1987. "Influence of the hydrothennal treatmerit on the catalytic behavior of mordenite and on the ah,1minum distribution in the crystallite", Applied Cata!., 35 (2): 311 - 320. https://doi.org/10.1016/S0166-9834(00)82869-9
Hays, G. R., Van Erp, W. A., Alma, N. C. M., Couperus, P.A., Huis, R. y Wilson, A.E., 1984. "Solid-state silicon NMR studies of the zeolite mordenite and its dealumination", Zeolites, 4 (4): 377 - 383. https://doi.org/10.1016/0144-2449(84)90015-0
Jacobs P: ,Y Vytterhoeven, J. B., 1971."Infrared study of deep-bed calcined ammoniurn-exchanged Y zeolites" , J. of Catal., 22 (2): 193 - 203. https://doi.org/10.1016/0021-9517(71)90185-0
Jansen, J. C., Vvan der Gaug, E. J. y Van Bekkum, H., 1984. "Identification of ZSM-type and other 5-ring containing zeolites by IR spedroscopy", Zeolites, 4 (4): 369 - 372. https://doi.org/10.1016/0144-2449(84)90013-7
Kerr, G. T., 1969. "Chemistry of crystalline aluminosili cates-7", J. of Catal., 15 (2): 200 - 204. https://doi.org/10.1016/0021-9517(69)90024-4
Lunsford, J. H., 1968. "Surface interactions of NaY and decationated Y zeolites with nitric oxide as determined by electron paramagnetic resonance spectroscopy. (Electron paramagnetic resonance study of interaction between adsorbed nitric oxide and NaY and decationized Y zeolites surfaces, considering catalytic activity)", J. Phys. Chem., 72 (Nov.): 4163 - 4168. https://doi.org/10.1021/j100858a037
Marvin, F. y Johnson, L., 1978. J. of Catal., 52,425. https://doi.org/10.1016/0021-9517(78)90346-9
Meyers, B. L., Fleisch, T. H., Ray, G. J., Miller, J. T., y Hall, J. B., 1988. "A multitechnique characterization of dealuminated mordenites", J. of Catal. , 11O (1): 82 - 95. https://doi.org/10.1016/0021-9517(88)90299-0
Mirodatos,.C., y Barthomeuf, D., 1981. "Superacid sites in zeolites", J. Chem. Soc., Chem. Commun., 2: 39- 40. https://doi.org/10.1039/c39810000039
Musa, M., Tarina, V., Stoica, A. D., Ivanov, E., Plostinaru, D., Pop, E., Poo, G. R., Garrea, R., Birjega, R., Musca,
G. y Paukshtis, E. A., 1987. "Sorne structural cbarac teristics of dealuminated synthetics mordenites", Zeolites, 7 (5): 427 - 432. https://doi.org/10.1016/0144-2449(87)90009-1
Pine, L. A., Maher , P. J., y Wachter, W. A., 1984. "Prediction of cracking catalyst behavior by a zeolite unit cell size model", J. of Catal., 85 (2): 466 - 476. https://doi.org/10.1016/0021-9517(84)90235-5
Raatz, F., Marcilly, C., y Freund, E., 1985. "Comparison between small port and large port mordeniles", Zeolites, 5 (5): 329 - 333. https://doi.org/10.1016/0144-2449(85)90168-X
Sawa, M., Niwa, M., y Murakami, Y., 1990. "Relationship between acid amount and framework aluminum content in mordenite", Zeolites, 10 (6): 532 - 538. https://doi.org/10.1016/S0144-2449(05)80308-2
Seddon, D., 1983. "Theconversionofaromatics over dealu minized mordenites", Applied Catal. , 7 (3): 327 - 336. https://doi.org/10.1016/0166-9834(83)80032-3
Scherzer, J., 1984. "The Preparation and Characterization of Aluminium Deficient Zeolites", in Catalytic Materia.Is, American Chemical Society, 157. https://doi.org/10.1021/bk-1984-0248.ch010
Shannon, R. D., Gardner, K. H. y Staley, R. H., 1985. "The nature of the nonframework aluminum species formed during the dehydroxylation of H-Y", J. Phys. Chem., 89(22): 4778 - 4788. https://doi.org/10.1021/j100268a025
Skeels, G. W., y Breck D. W., 1984. Procedings of the sixth international zeolite conference, Ed. Olson, D., y Bisio, A., Butterroorths, 87.
VanGeem, P. C., Scholle, K. F. M. G. J. y Van derVelden, G. P. M., E>'88. "Study of the transfo1mation of small port into arge-port mordenite by magic-angle spinning NMR and infrared spectroscopy", J. Phys. Chem., 92 (6): 1585 - 1589. https://doi.org/10.1021/j100317a042
Weller, S. W., y Bauer, J. M., 1969; Studies ofthe catalytic and Chemical Properties of acid-extracted mordenítes, Washington D.C., Preprint 62, Anual Meeting A.I.Ch.E.
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