Catalytic methanation

Nickel catalysts were used in most of the methanation catalytic studies they have a rather wide range of operating temperatures, approximately 260°-538°C. Operation of the catalytic reactors at 482°-538°C will ultimately result in carbon deposition and rapid deactivation of the catalysts (10). Reactions below 260°C will usually result in formation of nickel carbonyl and also in rapid deactivation of the catalysts. The best operating range for most fixed-bed nickel catalysts is 288°-482 °C. Several schemes have been proposed to limit the maximum temperature in adiabatic catalytic reactors to 482°C, and IGT has developed a cold-gas recycle process that utilizes a series of fixed-bed adiabatic catalytic reactors to maintain this temperature control. 

Methane reforming reaction is accomplished under the action of heat collected from mirror concentrator of solar light. The mixture of CO and H2 produced in this reaction can be stored and then, when necessary, converted into high-potential heat (with the temperature up to 950 K) in the methanation catalytic reactor. The efficiency of solar-to-chemical energy conversion as high as... 

Preliminary results of methane catalytic combustion indicated that Pt/H-MCM-22 sample showed a 100% conversion at 700°C with 100% selectivity toward the C02 formation. The sample showed also high thermal stability in fact, the catalytic activity was preserved after heating overnight at 800°C under air flow. (Catalytic data kindly provided by Ing. R. Pirone, Istituto di Ricerche sulla Combustione Italian CNR). 

Kim et al. [123] conducted the kinetic study of methane catalytic decomposition over ACs. Several domestic (South Korea) ACs made out of coconut shell and coal were tested as catalysts for methane decomposition at the range of temperatures 750-900°C using a fixed-bed reactor. The authors reported that no significant difference in kinetic behavior of different AC samples was observed despite the differences in their surface area and method of activation. The reaction order was 0.5 for all the AC samples tested and their activation energies were also very close (about 200 kj/mol) regardless of the origin. The ashes derived from AC and coal did not show appreciable catalytic effect on methane decomposition. 

Lisi, L Bagnasco, G Ciambelli, P Rossi, Sde Porta, P Russo, G Turco, M. Perovskite-type oxides II. Redox properties of LaMni.xCuxOs and LaCoi.xCuxOs and methane catalytic combustion. J. Sol State Chem., 1999, Volume 146, Issue 1, 176-183. 

The method determines the partial pressure of methane in the gas phase above the solution (Henry s law). Methane catalytically oxidizes on a heated platinum filament, that is part of a Wheatstone bridge. The heat generated increases the electrical resistance of the filament which is measured and compared against calibrated standards. 

Horn, R., Williams, K.A., Degenstein, N.J., Bitsch-Larsen, A., Dalle Nogare, D., Tupy, S.A., and Schmidt, L.D. Methane catalytic partial oxidation on autothermal Rh and Pt foam catalysts Oxidation and reforming zones, transport effects, and approach to thermodynamic equilibrium. Journal of Catalysis, 2007, 249 (2), 380. 

Percent, without controls Percent, with methane catalytic reduction... 

Dalla Betta, R.A. Loffler, D.G. Selectivity considerations in methane catalytic combustion. In Heterogeneous Hydrocarbon Oxidation Warren, B.K., Oyama, S.T., Eds. ACS Symposium Series 638 American Chemical Society Washington, DC, 1996 36-47. 

Methane catalytic conversion into carbon and hydrogen was examined over nickel-containing pentasil zeolites in a vacuum-circulation laboratory unit [4] at a catalyst/feed mass ratio of 5.0 and within a temperature range of 743 - 843 K. 

Alumina is widely used as a support for palladium oxide which is the most active phase for methane catalytic combustion [1]. Indeed, provided the reaction temperature does not exceed 900°C, alumina phase transformation is not favoured and sintering is limited. However, the active phase PdO decomposes into much less active metallic Pd above ca. 750°C [1]. It is therefore strongly... 

The 9A2B1 sample was used for supporting palladium (2 wt %). The resulting catalyst and the 2 wt % Pd/Al203 reference sample were studied in the methane catalytic combustion. Catalytic tests were performed in the temperature range of 300°C-900°C using 1% CH4, 4 % O2 and N2 balance at total flow rate of 36 L/h. Prior to catalytic activity measurements, samples were treated in the reaction mixture up to 900°C for stabilisation. Catalytic run consisted of heating from 300°C to 900°C at l°C/min. 

This work focuses on the kinetic study of the methane catalytic combustion in a honeycomb monolith wash-coated with Pd/y-AhOa (homemade). The experimental conditions were chosen to adequately represent the operation of a domestic-scale catalytic heater, i.e. relatively high volumetric flowrates and high methane molar fractions (Lopez et al., 2000). From experimental data (obtained at conditions of negligible mass transfer resistances) and using a mathematical model for the laboratory reactor, the intrinsic kinetic parameters are calculated for a power law type rate expression. 

Taylor JD, Allendorf MD, McDaniel AH, Rice SF In situ diagnostics and modeling of methane catalytic partial oxidation on Pt in a stagnation-flow reactor, Ind Eng Chem Res 42 6559-6566, 2003. 

Orddnez, S., Hurtado, R, Sastre, H., et al. (2004). Methane Catalytic Combustion over Pd/Al203 in Presence of Sulphur Dioxide Development of a Deactivation Model, Appl. Catal. A Gen., 259, pp. 41 8. 

Nogare, D., Degenstein, N., Horn, R., et al. (2011). Modeling Spatially Resolved Data of Methane Catalytic Partial Oxidation on Rh Foam Catalyst at Different Inlet Compositions and Flowrates, J. Catal, 277, pp. 134—148. 

Lisi L, Bagnasco G, Ciambelli P, De Rossi S, Porta P, Russo G, Turco M (1999) Perovskite-type oxides II. Redox properties of LaMn, CUj,-03 and LaCo, j,-Cuj,-03 and methane catalytic combustion. J Solid State Chem 146 176-183... 

Herrmann JM, Ramaroson E, Tempere JF. Semiconductivity study of ceria-supported nickel related to its methanation catalytic activity. Appl Catal A Gen. 1989 53(2-3) 117-34. 

Zheng X, Blowers P. A computational study of methane catalytic reactions on zeohtes. J Mol Catal A Chem 2006 246 1-10. 

The increased catalytic reactivity of methane on Pt at elevated pressures allows for significant fuel consumption at lower wall temperatures than those required at atmospheric pressure, thus facilitating an earlier microreactor ignition. This is evidenced in Figs. 8.6 and 8.7, where streamwise methane catalytic conversion rates and channel wall temperature profiles are plotted for Cases 1 and 5, atp = 1 and 5 bar, respectively. 

Fig. 8.6 Methane catalytic conversion rates along the microreactor during the startup phase for Cases 1 (bottom graph) and 5 (top graph), at 4 time instances ignition (ign), steady state (st) and two intermediate times. Cordierite wall material...

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