A Trickle Bed Reactor equipped with a non-ideal distribution tray is investigated. First, a non-ideal co-current trickling flow of nitrogen and heptane, induced by a partially plugged tray, is characterized experimentally using the g-tomography technique. Resulting liquid saturation data are used to validate the Euler-Euler CFD model developed in previous work of Solomenko et al.[16] on a 3D realistic flow. The resulting 3D CFD model is then coupled with simple isothermal kinetics of heteroatom removal of heavy petroleum cuts, and the effect of maldistribution on reactor performance is discussed. The problem of CFD model reduction to a 1D reactor model is finally addressed based on transport of internal ages distribution theory. Different 1D models are compared based on reactor effluent throughput. It is shown that a 1D-Multi Exit reactor model that respects both the age variance at the system outlet as well as the degree of mixing inside the reactor gives the best prediction of the reactor performance.