Methane, steam reforming over catalyst

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. 

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. 

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. 

INVESTIGATION OF SYNTHESIS GAS PRODUCTION FROM METHANE BY PARTIAL OXIDATION OVER SELECTED STEAM REFORMING COMMERCIAL CATALYSTS... 

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. 

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... 

A commercial nickel catalyst was used for methane steam reforming performed at a 500 °C reaction temperature, a S/C ratio of 3.0 and atmospheric pressure, while the permeate side was evacuated. The performance of the vapour deposited platinum membrane was similar to the plated dense palladium membrane. In the permeate of the deposited ruthenium and palladium membranes, small amounts of carbon oxides and also methane were observed. While it was expected that all these species had passed through the membranes by diffusion, in addition some methane was converted into carbon dioxide over the noble metals of the membranes. Kikuchi et al. demonstrated by simulations that conversion and hydrogen permeation in a membrane reactor is higher, where the first portion of the catalyst bed is not coupled to the membrane. Such an arrangement as shown in Figure 7.16 would clearly save expensive membrane surface area. Experimental work by Itoh et al. performed for methanol steam reforming [521] confirmed the assumptions of Kikuchi et al. 

Kinetic of methane steam reforming reaction over nickel- and rhodium-based catalysts. Appl. Catal. A Gen., 387 (1-2), 147-154. 

In addition to coke formation catalyzed by acids, heavy coke formation is observed in the reaction of methanation, Fisher-Tropsch synthesis, and steam reforming over metallic catalysts such as Fe and Ni. ° ... 

Hydrocarbons are converted into a mixture of hydrogen and oxides of carbon by reaction with steam over steam reforming catalysts. The reforming reaction is endothermic and the catalysts are packed into narrow tubes, which are heated in a furnace. The reforming furnace is commonly known as a reformer. An efficient methane steam reforming process was developed by 1936 and was first used on a large scale in North America during World War Two as shown in Ta-... 

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