Steam reforming reaction, methane

The extent to which anode polarization affects the catalytic properties of the Ni surface for the methane-steam reforming reaction via NEMCA is of considerable practical interest. In a recent investigation62 a 70 wt% Ni-YSZ cermet was used at temperatures 800° to 900°C with low steam to methane ratios, i.e., 0.2 to 0.35. At 900°C the anode characteristics were i<>=0.2 mA/cm2, Oa=2 and ac=1.5. Under these conditions spontaneously generated currents were of the order of 60 mA/cm2 and catalyst overpotentials were as high as 250 mV. It was found that the rate of CH4 consumption due to the reforming reaction increases with increasing catalyst potential, i.e., the reaction exhibits overall electrophobic NEMCA behaviour with a 0.13. Measured A and p values were of the order of 12 and 2 respectively.62 These results show that NEMCA can play an important role in anode performance even when the anode-solid electrolyte interface is non-polarizable (high Io values) as is the case in fuel cell applications. 

Ethanol and methane steam reforming reactions were studied assuming that the exit composition of the ethanol reformer depends on the steam reforming of methane. The competition for the same active site for ethanol and methane reforming maximizes the H2 and C02 production and minimizes the CO formation Catalysts were prepared by incipient wet impregnation. 20 wt% Ni supported on ZnO exhibited better performance compared to that supported on La203, MgO and A1203... 

A non-isothermal plug-flow membrane reactor on both sides of the membrane has been developed and applied to the methane steam reforming reaction to produce synthesis gas at high temperatures according to [Oeitel et al., 1987]... 

The performance of a CPO reactor is, in the literature, often characterized by the hydrocarbon conversion and selectivities to carbon monoxide and hydrogen. Methane conversion and selectivities are often reported to be more than 80-90%. This corresponds in general to conditions at which the exit gas is close to equilibrium for the shift reaction and the methane steam-reforming reaction with a low value of ATr in Eq. (5). The most likely reaction sequence is total oxidation in the initial part of the catalyst zone followed by other reactions including steam-reforming, shift, and possibly partial oxidation. 

The most important reactions taking place in catalytic steam reforming are the endothermic methane steam reforming reaction and the parallel exothermic water gas shift reaction, respectively [4] ... 

It has been also reported that the catalytic behaviour of Co catalysts for steam reforming of ethanol is enhanced by promotion with Fe or Mn as a consequence of the effect of these metals on cobalt reducibility. The catalytic activity of Co catalysts supported on ZnO and promoted with Fe and Mn (1 %) was compared with that of Ni catalysts supported on LaaOs-AlgOs. The Co catalysts do not promote methane-forming reactions such as ethanol cracking and acetaldehyde decarbonylation, nor do they facilitate the reverse methane steam reforming reaction. The promotion effect of Mn on Co/ZnO catalysts in the steam reforming of ethanol has been studied in coprecipitated catalysts. Alloy particles in Co-Mn/ZnO catalysts prepared by... 

Table 2.5 Methane eonversion and pinre hydrogen recovery data for methane steam reforming reaction...

De Falco M, Marrelli L, Basile A (2009) An industrial application of membrane reactors modelling of the methane steam reforming reaction, Chapter 9. In Simulation of membrane reactors. Nova Science Publishers Inc., New York, ISBN 978-1-60692-425-9... 

There are four extreme points to the convex polytope for this system, which indicates that there are four extreme points in extent space for the methane steam reforming reaction [1, 0] , [-0.25, 0.75] , [0, I] , and [0, 0] . ... 

Consider now a slight modification to the methane steam reforming reactions as follows ... 

In Chapter 8, we showed how the stoichiometric subspace for the methane steam reforming reaction can be computed in concentration space. Since the reaction occurs in the gas phase, it is more appropriate to determine the stoichiometric bounds in mass fraction space. This approach is preferable as the density of the mixture is no longer required to be constant. Compute the stoichiometric subspace for the CH4 steam reforming reaction and compare it to the answer obtained in Chapter 8. Assume that a feed molar vector of Uf = [1,1, l,0,0] kmol/s is available, and that the gas mixture obeys the ideal gas assumption to simplify calculations. Assume a constant pressure and temperature of P = 101 325 Pa and T = 500 K, respectively. 

Figure 9.9 (a) AR for the methane steam reforming reaction in mass fraction space, (b) Comparison of the stoichiometric subspace and... 

Gallucci, F., Paturzo, L Fama, A. and Basile, A. (2004) Experimental study of the methane steam reforming reaction in a dense Pd/Ag membrane reactor. Industrial and Engineering Chemistry Research, 43, 928-933. 

The methane steam reforming reaction R1 in Table 1.2 results in a H2/CO ratio close to 3. Steam can be replaced by CO2, resulting in a H2/CO ratio close to 1. The addition of oxygen in ATR and POX gives a... 

Figure4.16 Effect of the S/C ratio on the equilibrium composition of methane steam reforming reaction pressure, 1 bar reaction temperature, 600°C (dotted line), 700°C (dashed line), 800°C (straight line) [66].

Figure 5.1 Effect of reaction pressure on the equilibrium conversion of methane steam reforming reaction temperature, 700 °C S/C ratio 1 [66],...

Equilibrium composition of methane steam reforming reaction at a steam to carbon ratio of 3. 

Finally, products may react together, as for example the reactions between CO or CO2 and Hz, yielding CH4 (methanation reaction) or between two CO yielding CO2 and C (CO disproportionation reaction or Boudouard reaction). Thus, ethanol steam reforming gives rise to many reactions that are difficult to discriminate. However, it was shown that CO and CH4 are primary products, formed by ethanol cracking, which are then converted by water-gas shift reaction (reaction (24.3)) and methane steam reforming reaction [5]. 

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

Hacarlioglu, P., Gu, Y. and Oyama, S.T. (2006) Studies of the methane steam reforming reaction at high pressure in a ceramic membrane leactoi. Journal of Natural Gas Chemistry, 15, 73-81. 

Figure 11.4 Equilibrium constant of methane steam reforming reaction as a function of temperature.

Two reactions that seem to he catalyzed by the minerals present in ashes are (a) water-gas shift reaction and (b) methane-steam reforming reaction. The kinetics of water-gas shift reaction have been studied by variolas investigators (l8>6 >65 ... 

The methane-steam reforming reaction, the reverse reaction of methanation reaction, is believed to be catalyzed by the minerals present in coal. Zahradnik and Grace (6j) proposed the following expression for Pittsburg seam coal ... 

Percentage distribution of the catalysts used for carrying out the methane steam reforming reaction. 

Methane steam reforming reaction conversion versus temperature. 

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