Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

Results and DiscussionOP-IV-13Table 1 collects some properties of the alloys and catalysts. The atomic ratios (R = activemetal/total metal) show that residual amounts of Al (in the form of Al 2 O 3 ) are always presenton the catalyst upon activation, which may act as a textural promoter to prevent sintering.Figure 1 shows temperature programmed reaction tests on Ni30 (a), Co30 (b) and Fe50(c). It is observed that the catalytic activities of Ni and Co start at around 450ºC, negligibletraces of CO x being observed only at lower temperatures. Fe50 starts to be active at highertemperatures, and larger amounts of CO x are recorded.Table 1. Characterization of the alloys and catalystsAlloyCatalystSample R nominal R experimental R experimental S BET[m 2 /g]Ni30 0,165 0,17 ± 0,02 0,85 ± 0,07 64Ni50 0,315 0,39 ± 0,06 0,72 ± 0,07 82Co30 0,164 0,17 ± 0,02 0,94 ± 0,06 26Fe50 0,326 0,35 ± 0,09 0,95 ± 0,05 62Pressгo parcial (u.a.)2,0x10 -71,5x10 -71,0x10 -75,0x10 -8aH 2CO CH 40,00 100 200 300 400 500 600 700 800T (єC)Pressг o parcial (u.a.)2,0x10 -7 b1,5x10 -71,0x10 -75,0x10 -8H 2CO 2 CHCO40,00 100 200 300 400 500 600 700 800T (єC)Pressгo parcial (u.a.)2,0x10 -7 c1,5x10 -71,0x10 -75,0x10 -8CO 2COH 20,00 100 200 300 400 500 600 700 800T (єC)CH 4Figure 1. Temperature programmed reaction (a: Ni30, b: Co30, c: Fe50).Isothermal catalytic tests were subsequently performed in order to study the effects oftemperature, contact time, composition and concentration of the feedstream on the conversionof methane and catalyst stability. The results have shown that the best catalysts, Ni30 andCo30, could operate at 600 ºC without significant deactivation, with methane conversionshigher than 90% of the equilibrium value. The solid product was found to consist offilamentous carbon, containing both carbon nanofibres and carbon nanotubes.AcknowledgementsThis work was carried out with support from FCT (Portugal) and FEDER(BD/16035/2004 and POCTI/1181).References1. N. Muradov, T.N. Veziroglu, Int. J. Hydrogen Energy 30 (2005) 225.2. I. Suelves, M.J. Lázaro, R. Moliner, B.M. Corbella, J.M. Palacios, Int. J. Hydrogen Energy 30 (2005) 1555.3. U. Birkenstock, U.S. Patent 5,090,997, Bayer AG, H.C.Starck GmbH & Co. KG (1992).165