The steady state and dynamic behaviour of an adiabatic packed bed reac
tor for the selective hydrogenation of mixtures of ethyne and ethene i
s studied. A heterogeneous model with axial dispersion of heat is solv
ed numerically by means of a fully implicit discretisation scheme. Fro
m an analysis of the inlet and outlet boundary conditions, it follows
that in order to avoid an influence of the type of boundary condition
on the reactor behaviour, sufficiently long inert zones before and aft
er the active bed should be present. Using preliminary kinetic express
ions adapted from Men'shchikov et al. (1975), the model calculations s
how a reasonable agreement with the experiments performed in a laborat
ory scale reactor and demonstrate the importance influence of small am
ounts of carbon monoxide both on the steady state as well as on the tr
ansient behaviour of the reactor. However, using the rate expressions
derived from our own kinetic experiments in a Berty reactor, the behav
iour under runaway conditions and the transition from non-runaway to r
unaway conditions can not be described well. Several factors that cont
ribute to this discrepancy are discussed. This work shows that, in par
ticular for a complex reaction system such as the selective hydrogenat
ion of ethyne in ethene, the limited accuracy of the kinetic model and
kinetic parameters dominates the precision attainable with packed bed
reactor models.