A thermodynamic approach to the systematic elucidation of unique reaction routes in catalytic reactions

The directness (uniqueness) of both reaction routes (mechanisms) and overal l reactions is deduced from chemical thermodynamics. Namely, starting from general thermodynamic relations, the basic kinetic equation is shown to be identically transformed so as to be decomposable into a sum of contribution s originating from a finite and unique set of reactions called response rea ctions (RERs). For a general chemical reaction system involving terminal sp ecies (reactants and products) and intermediates, the basic kinetic equatio n may be further partitioned into contributions coming from RERs involving only terminal species and those RERs involving at least one intermediate. W hen the intermediate are assumed to obey the quasi-steady state approximati on, the contributions coming from the RERs involving at least one intermedi ate vanish. As a result, the basic kinetic equation may be presented as a s um of contributions coming from RERs involving only terminal species, i.e., overall RERs. This approach is shown to provide an adequate physicochemica l basis of mechanisms and overall reactions as well as an effective algorit hm of their enumeration. (C) 2000 Elsevier Science Ltd. All rights reserved .