Spectroscopic And Catalytic Studies On Cu-mcm-22: Effect Of Copper Loading

Copper exchanged MCM-22 zeolites with varying copper contents were prepared, characterized and tested in the nitrous oxide decomposition. Over-exchanged samples showed high activity, comparable to very active Cu-ZSM-5 catalysts. The nature of the copper species was investigated by TPR - H2, FTIR - CO and FTIR - NO, evidencing at least three different species: exchanged Cu2+ ions, cationic oligomeric species and oxidic phases. Upon NO adsorption, mononitrosilic complexes CuI - (NO) were formed, and completely oxidized to CuII - (NO) with increasing NO pressure. Nitrate complexes were extensively formed by reaction with the oxidic phases in the sample with 183% cation exchange level.142 A343350Armor, J.N., (1995) Catal. Today, 26, p. 99Leonowicz, M.E., Lawton, J.A., Lawton, S.L., Rubin, M.K., (1994) Science, 266, p. 1910Corma, A., Palomares, A.E.O., Fornés, V., (1998) Res. Chem. Intermed., 24, p. 613Mascarenhas, A.J.S., Andrade, H.M.C., Pastore, H.O., (2001) Stud. Surf Sci. Catal., 135, p. 322Frache, A., Cadoni, M., Bisio, C., Marchese, L., Mascarenhas, A.J.S., Pastore, H.O., J. Phys. Chem., , SubmittedRobson, H., (1998) Micropor. Mesopor. Mater., 22, p. 551Marques, A.L.S., Monteiro, J.L.F., Pastore, H.O., (1999) Micropor. Mesopor. Mater., 32, p. 131Iwamoto, M., Yahiro, H., Torikai, Y., Yoshoka, T., Mizuno, N., (1990) Chem. Lett., p. 1967Kapteijn, F., Marbán, G., Rodriguez-Mirasol, J., Moulijn, A.J., (1997) J. Catal., 167, p. 271Lamberti, C., Bordiga, S., Salvalaggio, M., Spoto, G., Zecchina, A., Geobaldo, F., Vlaic, M., Belatreccia, M., (1997) J. Phys. Chem. B:, 101, p. 344Márquez-Alvarez, C., McDougall, G.S., Guerrero-Ruiz, A., Rodríguez-Ramos, I., (1994) Appl. Surf Sci., 78, p. 477Wichterlová, B., Dedecek, J., Sobalík, Z., Vondrová, A., Klier, K., (1997) J. Catal., 169, p. 194Borgard, G.D., Molvik, S., Balaraman, P., Root, T.W., Dumesic, J.A., (1995) Langmuir, 11, p. 2065Rakic, V.M., Hercigonja, R.V., Dondur, V.T., (1999) Micropor. Mesopor. Mater., 27, p. 27Wasowicz, T., Prakash, A.M., Kevan, L., (1997) Microporous Mater., 12, p. 107Frache, A., Mascarenhas, A., Cadoni, M., Pastore, H.O., Marchese, L., in preparationJang, H.J., Hall, W.K., D'Itri, J.L., (1996) J. Phys Chem., 100, p. 9416Spoto, G., Bordiga, S., Scarano, D., Zecchina, A., (1992) Catal. Lett., 13, p. 39Palomino, G.T., Bordiga, S., Zecchina, A., Marra, G.L., Lamberti, C., (2000) J. Phys. Chem. B:, 104, p. 8641Konduru, M.V., Chuang, S.S.C., (2000) J. Catal., 196, p. 27

Catalytic supercritical water gasification of eucalyptus wood chips in a batch reactor

Eucalyptus wood chips were reacted under supercritical water conditions to evaluate the effect of a NiFe2O4 catalyst, residence time and temperature parameters. Experiments were performed in a batch reactor at 400 °C , 450 °C and 500 °C using three different amounts of catalyst (0, 1.0, 2.0 g) and three different residence times (30, 45, 60 min). Results showed that eucalyptus wood chips reacted and produced CO2 as the dominant gas in all cases, followed by H2 and CH4. However, the presence of NiFe2O4 catalyst led to a 60% increase in H2 produced, while significantly reducing the solid residue and enhancing the percentage of methyl derivatives in the organic liquid products. The highest H2 mol% was at 450 °C, 2 g of catalyst and 60 min of residence time. Analysis of the derived oils showed that they were mostly composed of ketones, aldehydes, methylbenzenes and alkylated phenols. Increasing the reaction temperature to 500 °C increased the molar composition of methane by 62% compared to its yield at 450 °C. In generally, this work showed that NiFe2O4 acted as an effective heterogeneous catalyst for improved production of H2 and CH4 via supercritical water gasification process