  In this work we study a 3-state ($+1$, $-1$, $0$) opinion model in the
presence of noise and disorder. We consider pairwise competitive interactions,
with a fraction $p$ of those interactions being negative (disorder). Moreover,
there is a noise $q$ that represents the probability of an individual
spontaneously change his opinion to the neutral state. Our aim is to study how
the increase/decrease of the fraction of neutral agents affects the critical
behavior of the system and the evolution of opinions. We derive analytical
expressions for the order parameter of the model, as well as for the stationary
fraction of each opinion, and we show that there are distinct phase
transitions. One is the usual ferro-paramagnetic transition, that is in the
Ising universality class. In addition, there are para-absorbing and
ferro-absorbing transitions, presenting the directed percolation universality
class. Our results are complemented by numerical simulations.
