caa a22 4500 463252454 CHVBK 20180405153344.0 cr unu---uuuuu 170326e20070201xx s 000 0 eng 10.1007/s10562-007-9028-6 doi (NATIONALLICENCE)springer-10.1007/s10562-007-9028-6 Silica-supported tantalum clusters: catalysts for conversion of methane with n -butane to give ethane, propane, and pentanes [Elektronische Daten] [Sailendra Nemana, Bruce Gates] Si02-supported tantalum clusters were prepared by adsorption of the precursor Ta(CH2Ph)5 (Ph is phenyl) on the support followed by treatments in H2 at 523, 623, and 723K. The resultant clusters, had approximate average diameters of 0.3, 0.8, and 2nm, as determined by extended X-ray absorption fine structure (EXAFS) spectroscopy. The samples were tested as catalysts for conversion of methane with n-butane in a once-through flow reactor operated at atmospheric pressure and 523K, and EXAFS spectroscopy was used to characterize the used catalysts. The results show that (a) the catalysts are active for the conversion of methane with n-butane to give ethane, propane, and pentanes; (b) catalytic activity decreased to nearly zero over a time on stream of 22 h; (c) the catalyst incorporating the smallest clusters exhibited the highest initial activity and that incorporating the largest clusters exhibited the lowest activity; (d) each used catalyst contained clusters of approximately the same nuclearity as the respective fresh catalyst, but with Ta-Ta bond lengths approximately 0.17Å longer than those found in the fresh catalysts. The data are consistent with catalysis by the supported clusters, and the product distributions are consistent with disproportionation of n-butane accompanied by the reaction of methane with propane to give other alkanes. Springer Science+Business Media, LLC, 2007 conversion of methane + n -butane nationallicence supported tantalum clusters nationallicence Nemana Sailendra Department of Chemical Engineering and Materials Science, University of California, 95616, Davis, CA, USA aut Gates Bruce Department of Chemical Engineering and Materials Science, University of California, 95616, Davis, CA, USA aut Catalysis Letters Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 113/3-4(2007-02-01), 73-81 1011-372X 113:3-4<73 2007 113 10562 https://doi.org/10.1007/s10562-007-9028-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10562-007-9028-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nemana Sailendra Department of Chemical Engineering and Materials Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Gates Bruce Department of Chemical Engineering and Materials Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 773 0- Catalysis Letters Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 113/3-4(2007-02-01), 73-81 1011-372X 113:3-4<73 2007 113 10562 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer