Figure shows the corresponding spatial profiles of molar fractions and the reaction rate profiles for 𝑧 = 0.5. It becomes obvious that the diffusion limitations are strongly pronounced and that the interior of the pellets is hardly used for reaction. Furthermore, the principle trend observed for the 5 wt.-% nickel catalyst, namely that CO is hydrogenated close to the external surface, while CO2 methanation is favored at small residual CO fraction is obtained, as well. Hence, the principles for the catalyst with lower nickel loading discussed above also hold for the industrially relevant counterpart with respect to the general trends. However, in comparison to figure , the effectiveness factor of the tenfold active catalyst is smaller, since the effective methane formation rate exceeds zero only in a thin layer of 1.3 ≤ 𝑦 mm ⁄ ≤ 1.5. Furthermore, equilibrium conditions are reached in the center of the catalyst pellet, which is revealed by calculations using the Gibbs-energy minimization model . Since nickel is a commodity metal, it is useful for many applications to introduce as much as possible into the reactor as a reservoir against catalyst deactivation. The long operating times achieved in this way can often compensate for the low initial utilization. Furthermore, the unused portion of the catalyst pellet allows to compensate for changes in the concentration of the reactants. Specifically, the reaction rate profiles for CO and CO2 methanation develop depending on the reactant composition, while the overall CH4 formation rate remains rather unaffected as shown in figure . Hence, the entire reactor is more tolerant towards concentration variations . However, industrial catalysts with high Ni loading and larger pellet sizes are not suitable for targeted CO conversion compared to smaller, less active catalysts.