“…Coverage effects of this type have been previously considered through modified microkinetic models − and by kinetic Monte Carlo methods − that implicitly or explicitly account for co-adsorbate interactions. Here, we will instead account for these co-adsorbate interactions by treating dense adlayers of adsorbates as thermodynamically nonideal systems for which the rates of surface reactions depend on their “areas of activation”, through an analogy with the activation volumes often used for homogeneous reactions in dense and nonideal liquid and gaseous media. − Specifically, we address the effects of dense CO* adlayers and assess the adequacy of Langmuirian models for CO hydrogenation on Ru-based catalysts, ,− widely used along with Ni, − Co, ,− and Fe − catalysts, in methanation and Fischer–Tropsch synthesis (FTS). High CO pressures (>100 kPa) shift reaction selectivities from CH 4 products to larger hydrocarbons and lead to very dense saturated CO adlayers at all relevant conditions (450–550 K, 0.1–5 MPa).…”