The role of desorption of a dimer in a heterogeneous catalytic surface reactor of type A/sub 2/ + 2B/sub 2/ ---> 2AB/sub 2/

The kinetics of an irreversible dimer-dimer surface reaction of the type A/sub 2/+2B/sub 2/ --> 2AB/sub 2/ with desorption of B/sub 2/ has been investigated by means of Monte Carlo simulation. For a desorption probability (P) of B/sub 2/ equal to zero, a single discontinuous transition separating an A and AB-saturated surface from a B-saturated surface is obtained exactly at the stoichiometric ratio of the reaction. With the increase in P, a steady reactive state which is separated from the poisoned states by two continuous transition is obtained. The position of the critical points depends upon the value of P. (author)