Bridging the "Pressure Gap" between Ultrahigh-Vacuum Surface Physics and High-Pressure Catalysis

It is shown that it is possible to calculate the ammonia synthesis rate in a catalytic reactor at industrial conditions (150-300 atm, 375-500\ifmmode^\circ\else\textdegree\fi{}C) starting from measurements of the properties of the reactants on well-defined single-crystal surfaces under ultrahigh-vacuum conditions. A generalized form of Fowler and Guggenheim's statistical mechanical treatment of adsorption is used in conjunction with the reaction scheme proposed by Ertl et al. The calculation contains no adjustable parameters and reproduces experimental data over a broad range of conditions.