We study the process of pattern selection in a large class of heterogeneous models of catalytic reactors by analyzing the behavior of a simple condensed model, which obeys reflection and inversion symmetries and which captures the main features of a detailed model. The three-variable model incorporates a very fast and long-ranged variable, which may describe the fluid phase in a mixed, plug-flow or an axial-dispersion reactor or the pore phase in a catalytic particle, and two variables - a medium-ranged activator and a localized inhibitor - that describe the solid phase. Patterns are classified according to their symmetry properties. Patterns may emerge already with simple bistable kinetics in a plug-flow reactor (i.e., a single integrodifferential equation). Pattern selection is determined by the phase planes spanned by the reactor, by the ratio of front residence time to the period of oscillations and by the ratio of convection to fluid-phase diffusions terms. Patterns include stationary or oscillatory fronts or pulses, antiphase oscillations which appear at the transition from homogeneous solution, unidirectional pulses that are the dominant patterns when mixing is weak and stationary or oscillatory waves that emerge with strong fluid-mixing. The simple form of the model allows us to suggest a general classification of emerging patterns and to identify the corresponding conditions in term of realistic models of reactors.