  Five dimensional dilaton models are considered as possible holographic duals
of the pure gauge QCD vacuum. In the framework of these models, the QCD trace
anomaly equation is considered. Each quantity appearing in that equation is
computed by holographic means. Two exact solutions for different dilaton
potentials corresponding to perturbative and non-perturbative beta-functions
are studied. It is shown that in the perturbative case, where the beta-function
is the QCD one at leading order, the resulting space is not asymptotically AdS.
In the non-perturbative case, the model considered presents confinement of
static quarks and leads to a non-vanishing gluon condensate, although it does
not correspond to an asymptotically free theory. In both cases analyses based
on the trace anomaly and on Wilson loops are carried out.
