Steam reforming methane over

In a number of publications, Rostrup-Nielsen discusses different mechanism of methane steam reforming over Ni catalysts [17]. The proposed simplified reaction sequence for reforming of methane is as follows ... 

Fonseca, A. and Assaf, E.M. Production of the hydrogen by methane steam reforming over nickel catalysts prepared from hydrotalcite precursors. Journal of Power Sources, 2005, 142 (1-2), 154. 

Halabi, M. H., De Croon, M. H. J. M., Van Der Schaaf, J., Cobden, P. D., Schouten, J. C. (2010). Low temperature catalytic methane steam reforming over ceriaezirconia supported rhodium. Applied Catalysis A General, 389, 68—79. 

Jones, G., Jakobsen, J. G., Shim, S. S., Kleis, J., Andersson, M. P., Rossmeis Pedersen, E. A., et al. (2008). Eirst principles calculations and experimental insight into methane steam reforming over transition metal catalysts. Journal of Catalysis, 259, 147—160. 

Kusakabe, K., Sotowa, K. I., Eda, T., Iwamoto, Y. (2004). Methane steam reforming over Ce-Zr02-supported noble metal catalysts at low temperature. Fuel Processing Technology, 86, 319—326. Scopus Exact. 

Laosiripojana, N., Assabumrungrat, S. (2005). Methane steam reforming over Ni/ Ce-Zr02 catalyst influences of Ce-Zr02 support on reactivity, resistance toward carbon formation, and intrinsic reaction kinetics. Applied Catalysis A General, 290, 200-211. 

Luna, E. C., Becerra, A. M., Dimitrijewits, M. I. (1999). Methane steam reforming over rhodium promoted Ni/ALOa catalysts. Reaction Kinetics and Catalysis Letters, 67, 247-252. 

Pumomo, A., Gallardo, S., AbeUa, L., Salim, C., Hinode, H. (2008). Effect of ceria loading on the carbon formation during low temperature methane steam reforming over a Ni/Ce02/ Zr02 catalyst. Reaction Kinetics and Catalysis Letters, 95, 213—220. 

Turn-over numbers have been reported for methane steam reforming over alumina-supported catalyst systems [214] ... 

Robbins et al. performed transient modelling of methane steam reforming over a 1.7 wt.% rhodium/y-alumina catalyst combined with hydrogen or methane combustion over a 0.6 wt.% paUadium/y-alumina catalyst in a co-current plate heat-exchanger... 

Jones, G. Jakobsen, J.G. Shim, S.S. Kleisa, J. Andersson, M.P. Rossmeisl, J. Abild-Pedersen, R Bligaard, T Helveg, S. Hinnemann, B. J. Rostrap-Nielsen, R. Chorkendorff, L Sehested, J. Noskov, J.K. First Principles Calculations and Experimental Insight into Methane Steam Reforming over Transition Metal Catalysts. J. Catal. 2008,259,147-160. 

Hou K and Hughes R, The kinetics of methane steam reforming over a Ni/a-A120... 

Na.tura.1 Ga.s Reforma.tion. In the United States, most hydrogen is presently produced by natural gas reformation or methane—steam reforming. In this process, methane mixed with steam is typically passed over a nickel oxide catalyst at an elevated temperature. The reforming reaction is... 

Catalysts were prepared by incipient wetness impregnation of commercial supports using cobalt nitrate as a precursor. Metallic cobalt species were active centers in the ethanol steam reforming. Over 90% EtOH conversion achieved. Nature of support influences the type of byproduct formation. Ethylene, methane and CO are formed over Co supported on A1203, Si02 and MgO, respectively... 

The purified gas is fed into the Synthol and fixed-bed reactors. The products from the reactors are cooied and separated in a water phase, oil phase and tail gas. The + Ca olefinic products from the tail gas are separated in an oil absorption tower and oligomerized over an acidic catalyst to gasoline. Tite remaining tali gas can be treated in a cryogenic unit to provide methane and hydrogen, which is partly used as fuel gas or feedstock for ammonia synthesis. The remainder is steam-reformed over nickel catalysts to give CO/H3. 

They reported similar findings to those of Bodrov et al (1967) including the attainment of a steady state after 40 hours and they represented the kinetic data by similar expressions. Xu and Froment (1989) studied the steam reforming of methane over a crushed nickel-magnesium-alumina catalyst containing 15% nickel in a reactor of 10.7mm diameter at temperatures between 500 and 575°C and pressures between 5 and 15 bar. Soliman et al (1992) studied steam reforming over a nickel-calcium aluminate-spinel catalyst in a commercial microreactor 6mm in diameter at temperatures from 475 to 550 C and pressures from 2 to 4 atmospheres. 

That are the water gas shift (WGS) reaction [Eq. (3.4)], which is very important when fuel ricii in CO is fed the combustion reactions [Eqs. (3.5) and (3.6)] due to an undesired gas cross-over from one electrode side to the other, and finally the methane steam reforming [Eq. (3.7)], which can provide the hydrogen when the fuel contains methane. 

Batista et al. performed ethanol steam reforming over cobalt/alumina and cobalt/ silica catalysts containing 8 and 18wt.% cobalt [201]. Even with a reaction temperature of400 °C, 70% conversion could be achieved. Methane was the main by-product, ethylene was only formed over samples containing 8 wt.% cobalt. Then a bed of an iron oxide/chromium oxide water-gas shift catalyst was switched behind the cobalt/ silica catalyst. The carbon monoxide was converted as expected, but also less methane was found in the product [202]. Even less carbon monoxide was formed when both catalysts were mixed. Sahoo et al. varied the cobalt content of the cobalt/alumina catalyst from 10 to 20 wt.%. The highest activity was determined for the sample containing 15 wt.% cobalt [203]. 

Table 5.4 Experimental results of methane steam reforming in a gap of 76- j,m height over a rhodium/magnesia/alumina catalyst coating at different contact time [385].

To model the performance of the autothermal reformer, kinetics from the literature that had been determined for the catalytic combustion of methane over a platinum-based catalyst and for steam reforming over nickel-based catalyst were combined and fitted to the experimental data of Flytzani-Stephanopoulos et al. [153]. The water-gas shift reaction was assumed to reach thermodynamic equilibrium under all conditions in the reformer reactor, which is usually the case in reformers. Methane formation was not considered. Because catalyst pellets had been used for the determination of the kinetics, diffusion limitations were to be expected. They had been lumped into the kinetic models. The hot spot formation usually observed at... 

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