The results just examined regarding the influence of the catalyst layer
thickness can be qualitatively appreciated analyzing the size of the species
concentration gradients in the transverse direction. This can be done observing the
transverse concentration profiles of the species in the reactor, at 0.5 cm from the
reactor inlet and at 0.5 cm before the reactor outlet, shown in Figures 7a and 7b,
respectively. In particular, the concentration profiles, pertaining to the various
species present in the reactor, evidence that the gradients inside the channels are
negligible with respect to the gradients in the catalyst phases close to the gascatalyst
interface. The order of magnitude of these latter ranges from 105 mol/m4
close to the reactor inlet to 104 mol/m4 further along the reactor. In addition, it is
also evident that after some distance from the gas-catalyst layer interface the
methane concentration in the combustion catalyst and the concentration gradients
of all the species becomes zero. This behavior reflects the quantitative results,
reported in Table 5, substantially indicating that a catalyst layer, with the
characteristics specified in this work, deeper than 50 μm is useless.
The results just examined regarding the influence of the catalyst layerthickness can be qualitatively appreciated analyzing the size of the speciesconcentration gradients in the transverse direction. This can be done observing thetransverse concentration profiles of the species in the reactor, at 0.5 cm from thereactor inlet and at 0.5 cm before the reactor outlet, shown in Figures 7a and 7b,respectively. In particular, the concentration profiles, pertaining to the variousspecies present in the reactor, evidence that the gradients inside the channels arenegligible with respect to the gradients in the catalyst phases close to the gascatalystinterface. The order of magnitude of these latter ranges from 105 mol/m4close to the reactor inlet to 104 mol/m4 further along the reactor. In addition, it isalso evident that after some distance from the gas-catalyst layer interface themethane concentration in the combustion catalyst and the concentration gradientsof all the species becomes zero. This behavior reflects the quantitative results,reported in Table 5, substantially indicating that a catalyst layer, with thecharacteristics specified in this work, deeper than 50 μm is useless.
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