High-temperature applications steam methane reforming

In some applications water-gas-shift (WGS) is coupled with other reactions. For example, the steam reforming of methane to produce hydrogen is one example where both the forward and reverse reaction may be involved. However, this reaction is accomplished at high temperatures and the reaction is usually considered to be at equilibrium at the high temperatures used. In the following these high temperature processes will not be covered only those instances where the WGS reaction is the dominant reaction that is used to produce and/or purify hydrogen is considered. 

The second application of availability analysis is used to evaluate the nature and magnitude of thermodynamic irreversibilities in a methane reformer plant coupled to a high-temperature nuclear reactor. It is shown that a combination of thermal histograms and availability concepts are helpful not only in evaluating the net impact of irreversibilities in various chemical process steps on the steam power plant, but, more importantly, 1n suggesting process modifications that could improve the overall efficiency by avoiding unnecessary entropy production. 

Theoretical infinite selectivity can be achieved for hydrogen separation by Pd or Pd-alloy membranes. Hydrogen is one of the most important gases for industrial applications and its production is principally based on steam reforming of methane. The reaction is carried out at high temperature, about above 1000 K, because of the equilibrium of the endothermic reactions involved in the process ... 

Elemental hydrogen is one of the more widely produced industrial chemicals. For use in chemical synthesis and other industrial applications, it is commonly made by steam reforming of methane (natural gas, CH4) under high-temperature, high-pressure conditions ... 

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. 

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