Performance Of Pd Supported On Mesoporous Molecular Sieves On Methane Combustion

The performance of Pd-based catalysts supported on mesoporous molecular sieves with different pore arrangement (MCM-41 and MCM-48) was investigated for methane combustion. All molecular sieves showed to be thermally stable, evidencing the suitability of these materials as support for high temperature processes and motivated the efforts to exploit their use. Reaction data showed that silicate-based samples rendered more active catalysts than those prepared on aluminosilicate; activity was affected by monodimensional or three-dimensional pore arrangement. The use of molecular sieves in proton form led to an increase in the reaction rate in relation to the sodium form. © 2011 Elsevier B.V. All rights reserved.2516Gélin, P., Primet, M., (2002) Applied Catalysis B: Environmental, 39, pp. 1-37Wierzchowski, P.T., Zatorski, L.W., (2003) Applied Catalysis B: Environmental, 44, pp. 53-65Choudhary, T.V., Banerjee, S., Choudhary, V.R., (2005) Catalysis Communications, 6, pp. 97-100Yuranov, I., Moeckli, P., Suvorova, E., Buffat, P., Kiwi-Minsker, L., Renken, A., (2003) Journal of Molecular Catalysis A, 192, pp. 239-251Maeda, H., Kinoshita, Y., Reddy, K.R., Muto, K., Komai, S., Katada, N., Niwa, M., (1997) Applied Catalysis A, 163, pp. 59-69Wierzchowski, P.T., Zatorski, L.W., (2002) Catalysis Letters, 78, pp. 171-176Okumura, K., Matsumoto, S., Nishiaki, N., Niwa, M., (2003) Applied Catalysis B: Environmental, 40, pp. 151-159Ishihara, T., Sumi, H., Takita, Y., (1994) Chemistry Letters, 23, pp. 1499-1502Takita, Y., Ishihara, T., Nishiguchi, H., Sumi, H., (1997) Studies in Surface Science and Catalysis, 105, pp. 1647-1654Venezia, A.M., Murania, R., Pantaleo, G., Deganello, G., (2007) Journal of Catalysis, 192, pp. 94-102Ruiz, J.A.C., Fraga, M.A., Pastore, H.O., (2007) Applied Catalysis B: Environmental, 76, pp. 115-122Wang, Z.J., Liu, Y., Shi, P., Liu, C.J., Liu, Y., (2009) Applied Catalysis B: Environmental, 90, pp. 570-577Bassil, J., Albarazi, A., Da Costa, P., Boutros, M., (2011) Catalysis Today, 176, pp. 36-40Pastore, H.O., Munsignatti, M., Bittencourt, D.R.S., Rippel, M.M., (1999) Microporous and Mesoporous Materials, 32, pp. 211-228Cónsul, J.M.D., Peralta, C.A., Benvenutti, E.V., Ruiz, J.A.C., Pastore, H.O., Baibich, I.M., (2006) Journal of Molecular Catalysis A, 246, pp. 33-38Xia, Y., Mokaya, R., (2003) Journal of Materials Chemistry, 13, pp. 657-659Panpranot, J., Pattamakomsan, K., Goodwin, J.G., Praserthdam, P., (2004) Catalysis Communications, 5, pp. 583-590Araujo, A.S., Fernandes, Jr.V.J., Veríssimo, S.A., (2000) Journal of Thermal Analysis and Calorimetry, 59, pp. 649-655Bezman, R., (1981) Journal of Catalysis, 68, pp. 242-244Fraga, M.A., Souza, E.S., Villain, F., Appel, L.G., (2004) Applied Catalysis A, 259, pp. 57-63Pena, M.L., Kan, Q., Corma, A., Rey, F., (2001) Microporous and Mesoporous Materials, 44, pp. 9-16Rakai, A., Tessier, D., Bozon-Verduraz, F., (1992) New Journal of Chemistry, 16, pp. 869-875Lomot, D., Juszczyk, W., Pielaszek, J., Kaszkur, Z., Bakuleva, T.N., Karpinski, Z., (1995) New Journal of Chemistry, 19, pp. 263-273Ruiz, J.A.C., Melo, D.M.A., Souza, J.R., Alcazar, L.O., (2002) Materials Research, 5, pp. 173-178Sekizawa, K., Widjaja, H., Maeda, S., Ozawa, Y., Eguchi, K., (2000) Applied Catalysis A, 200, pp. 211-217Eguchi, K., Arai, H., (2001) Applied Catalysis A, 222, pp. 359-367M'Ramadj, O., Li, D., Wang, X., Zhang, B., Lu, G., (2007) Catalysis Communications, 8, pp. 880-884Truitt, M.J., Toporek, S.S., Rovira-Hernandez, R., Hatcher, K., White, J.L., (2004) Journal of the American Chemical Society, 126, pp. 11144-11145Wang, J.G., Liu, C.J., (2006) Journal of Molecular Catalysis A, 247, pp. 199-205Liu, W., Flytzani-Stephanopoulos, M., (1995) Journal of Catalysis, 153, pp. 304-316Zhang, C.J., Hu, P., (2002) The Journal of Chemical Physics, 116, pp. 4281-4285Fujimoto, K., Ribeiro, F., Avalos-Borja, M., Iglesia, E., (1998) Journal of Catalysis, 179, pp. 431-44

Direct Decomposition Of Nitric Oxide On Bimetallic Catalysts: Effect Of Metals Bonding

Pd-Mo and Mo-Pd bimetallic catalysts supported on Al2O3-thin-layer-modified SiO2 and Si-MCM-41 were investigated for the direct decomposition of nitric oxide. The catalysts were prepared from [Pd(acac)2] and [Mo(CO)6]. The Al2O3/SiO2 and Al2O3/Si-MCM-41 supported catalyst surface areas did not change significantly upon metal impregnation. Temperature programmed reduction profiles suggest the presence of large particles that are easily reduced. Consequently, low palladium dispersions were found. All the catalysts studied were active in the NO decomposition reaction, Mo-Pd catalysts being the most selective. © 2007 Elsevier B.V. All rights reserved.133-1351-4475479Alloway, B.J., Ayres, D.C., (1994) Chemical Principles of Environmental Pollution, , Blackie Academic & Professional, LondonWang, X., Spivey, J.J., Lamb, H.H., (2005) Appl. Catal. B: Environ., 56, p. 261Nazimek, D., Ćwikta-Bundyra, W., (2004) Catal. Today, 90, p. 39Mariadassou, G.D., Fajardie, F., Tempère, J.F., Manoli, J.M., Touret, O., Blanchard, G., (2000) J. Mol. Catal. A: Chem., 161, p. 179Wang, J., Ji, S., Yang, J., Zhu, Q., Li, S., (2005) Catal. Commun., 6, p. 389Burch, R., Breen, J.P., Meunier, F.C., (2002) Appl. Catal. B: Environ., 39, p. 283Parvulescu, V.I., Grange, P., Delmon, B., (1998) Catal. Today, 46, p. 233Traa, Y., Burger, B., Weitkamp, J., (1999) Micropor. Mesopor. Mater., 30, p. 3Fritz, A., Pitchon, V., (1997) Appl. Catal. B: Environ., 13, p. 1Liu, Z., Woo, S.I., (2006) Catal. Rev. Sci. Eng., 48, p. 43Sica, A.M., Baibich, I.M., Gigola, C.E., (2003) J. Mol. Catal. A: Chem., 195, p. 225Kresge, C.T., Leonowicz, M.E., Roth, W.J., Vartuli, J.C., Beck, J.S., (1992) Nature, 357, p. 710Wan, K., Liu, Q., Zhang, C., (2003) Mater. Lett., 57, p. 3839Iengo, P., Serio, M.D., Sorrentino, A., Solinas, V., Santacesaria, E., (1998) Appl. Catal. A: Gen., 167, p. 85Cónsul, J.M.D., Baibich, I.M., Benvenutti, E.V., Thiele, D., (2005) Quím. Nova, 28, p. 393Li, M., Seshan, K., Lefferts, L., (2004) Appl. Catal. B: Environ., 50, p. 143Naito, S., Iwahashi, M., Kawakani, I., Miyao, T., (2002) Catal. Today, 73, p. 355Mariadassou, G.D., (2004) Catal. Today, 90, p. 27Cónsul, J.M.D., Peralta, C.A., Benvenutti, E.V., Ruiz, J.A.C., Pastore, H.O., Baibich, I.M., (2006) J. Mol. Catal. A: Chem., 246, p. 33Tonetto, G.M., Ferreira, M.L., Damiani, D.E., (2003) J. Mol. Catal A: Chem., 193, p. 121Konsolakis, M., Yentekakis, I., (2001) J. Catal., 198, p. 142Armor, J.N., (1992) Appl. Catal. B: Environ., 1, pp. L31Sica, A.M., Gigola, C.E., (2003) Appl. Catal. A: Gen., 239, p. 121Eberhardt, A.M., Benvenutti, E.V., Moro, C.C., Tonetto, G.M., Damiani, D.E., (2003) J. Mol. Catal. A: Chem., 201, p. 247de Almeida, R.M.J., Pergher, S.B.C., Gigola, C.E., Baibich, I.M., (2003) Can. J. Anal. Sci. Spectrosc., 48, p. 21Baibich, I.M., dos Santos, J.H.Z., da Silveira, V.C., Gigola, C., Sica, A.M., (1998) Can. J. Anal. Sci. Spectrosc., 43, p. 26Pastore, H.O., Munsignatti, M., Bittencourt, D.R.S., Rippel, M., (1999) Micropor. Mesopor. Mater., 32, p. 211Dallago, R.M., Schifino, J., Baibich, I.M., Veses, R.C., (2004) Can. J. Anal. Sci. Spectros., 49, p. 78Konopny, L., Juan, A., Damiani, D., (1998) Appl. Catal. B: Environ., 15, p. 115Noronha, F.B., Baldanza, M.A.S., Schmal, M., (1999) J. Catal., 188, p. 27

A Nano-organized Ethylene Oligomerization Catalyst: Characterization And Reactivity Of The Ni(mecn)6(bf4)2/[al]-mcm-41/alet 3 System

The complex Ni(MeCN)6(BF4)2 has been immobilized on [Al]-MCM-41 (Ni/[Al]-MCM-41) and characterized by X-ray diffraction (XRD), N2 adsorption, transmission electron microscopy (TEM), diffuse reflectance infrared spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS). The heterogeneized system retains the catalytic properties of its molecular precursor: the immobilized complex associated with AlEt3 is active in heterogeneous phase ethylene oligomerization under mild reaction conditions. The AlEt3/nickel molar ratio Al/Ni has shown to be a fundamental parameter to control the selectivity of the system into 1-butene. Under typical reaction conditions, 313 K and 0.98 MPa of ethylene and Al/Ni molar ratio of 15, selectivities of ca. 84% in 1-butene have been obtained. © 2006 Elsevier Inc. All rights reserved.9601/03/15109114Wittcoff, H.A., Reuben, B.G., (1980) Industrial Organic Chemicals in Perspective, , Wiley, New YorkKeim, W., (1990) Angew. Chem. Int. Ed. Engl., 29, p. 235Skupinska, J., (1991) Chem. Rev., 91, p. 613Pardy, R.B.A., Tkatchenko, I., (1981) J. Chem. Soc. Chem. Commun., 2, p. 49Commereuc, D., Chauvin, Y., Gaillard, J., Léonard, J., Andrews, J., (1983) Hydrocarb. Process., 13, p. 46Kresge, C.T., Leonowicz, M.E., Roth, W.J., Vartuli, J.C., Beck, J.S., (1992) Nature, 359, p. 710Sing, K.S.W., Everett, D.H., Haul, R.H.W., Moscou, L., Pierotti, R.A., Rouquerol, J., Siemieniewska, T., (1985) Pure Appl. Chem., 57, p. 603Taguchi, A., Schüth, F., (2005) Micropor. Mesopor. Mater., 77, p. 1Hulea, V., Fajula, F., (2004) J. Catal., 225, p. 213de Souza, F.R., Oberson de Souza, M., Monteiro, A.L., Almeida, L., Seferin, M., (1993) New J. Chem., 17 (7), p. 437Pastore, H.O., Munsignatti, M., Bittencourt, D.R.S., Rippel, M.M., (1999) Micropor. Mesopor. Mater., 32, p. 211Souza, R.F., Monteiro, A.L., Seferin, M., de Souza, M.O., Stedile, F.C., Wyrwalski, C.N., Baumvol, I.J.R., (1996) J. Coord. Chem., 40, p. 311Vale, M.G.R., Damin, I.C.F., Klassen, A., Silva, M.M., Welz, B., Silva, A.F., Lepri, F.G., Heitmann, U., (2004) Microchem. J., 77, p. 131Buschmann, W.E., Miller, J.S., (1998) Chem. Eur. J., 4, p. 1731Pillinger, M., Gonçalves, I., Valente, A.A., Ferreira, P., Schön, D., Nuyken, O., Kühn, F.E., (2001) Des. Monomers Polym., 4, p. 269Tolman, C.A., Riggs, W.M., Linn, W.J., King, C.M., Wendt, R.C., (1973) Inorg. Chem., 12, p. 2770Matienzo, L.J., Yin, L.I., Grim, S.O., Swartz Jr., W.E., (1973) Inorg. Chem., 12, p. 2762Alvaro, S.F., Eib, W., Meier, F., Siegmann, H.C., Zurcher, P., (1978) Photoemission and the Electronic Properties of Surfaces, , Feuerbacher B., Fitton B., and Willis R.F. (Eds), John Wiley & Sons, Londonde Souza, M.O., Mendes, F.M.T., de Souza, R.F., do Santos, J.H.Z., (2004) Micropor. Mesopor. Mater., 69, p. 21

Three new teosintes (Zea spp., Poaceae) from M�xico

Premise of the study: Teosinte species are the closest relatives of maize and represent an important but increasingly rare genetic resource for maize improvement and the study of evolution by domestication. Three morphologically and ecologically distinct teosinte populations were recently discovered in M � xico. The taxonomic status of these rare and endangered populations was investigated by detailed comparisons to previously characterized wild Zea species.Methods: Three new teosinte populations were compared to known teosinte taxa on the basis of morphological, ecogeographic, cytological, and molecular characteristics. Phenetic and phylogenetic analyses were performed using morphological and molecular data, respectively.Key results: The newly discovered populations are distinct from each other and from other Zea species to represent three new entities based on their unique combinations of morphological, ecological, ploidy, and DNA markers. A perennial diploid population from Nayarit is distinguished by early maturing plants, and having male inflorescences with few tassel branches and long spikelets. A perennial tetraploid population from Michoac � n is characterized by tall and late maturing plants, and having male inflorescences with many branches. An annual diploid population from Oaxaca is characterized by having male inflorescences with fewer branches and longer spikelets than those found in the sister taxa Z. luxurians and Z. nicaraguensis, plants with high thermal requirements, and very long seed dormancy.Conclusions: Evidence from multiple independent sources suggests placement of the three new populations of teosinte as distinct entities within section Luxuriantes of the genus Zea. However, more extensive DNA marker or sequence data are required to resolve the taxonomy of this genus. � 2011 Botanical Society of America