ABSTRACT
Two- and three-dimensional phases arising as a result of adsorption, for example, oxide films on metal surfaces, can play an important role in heterogeneous catalysis. The role of phase transitions in heterogeneous catalysis has been a widely debated topic for a long time. Opinions differ as to the equilibrium or non-equilibrium catalyst state in conditions of stationary catalysis. The kinetic and thermodynamic aspects of creation and decomposition of solid phases were considered by Langmiur using the decomposition of calcium carbonate. Later evolution of catalytic science proved the validity of Langmuir's notions connected with reaction passing in the vicinity of the boundary between phases in the two-phase system. L. Rieckert et al. proved experimentally that the redox catalysts are two-phase in the stationary state of deep H2 and C3H6 oxidation. The widespread use of Low energy electron diffraction (LEED) gave rise to discovery of the 2-D phase transformations.
