While previous studies experimentally demonstrated sustained operation in a loop reactor (using ethylene or methane combustion), and analyzed the single-reaction case and suggesting a proper control scheme, an actual implementation of VOC combustion will involve several reactants of varying concentrations. Here we study the dynamics and design implications of a bi-species (methane or ethane and ethylene) and a multi-species combustion. We observe two main structures in which the two fronts are either locked or are separated, with the combustion front of the less reactive component leading the other front. We explain why the locked front structure is favorable as it requires smaller energy investment. We derive approximations for the front properties (maximal temperature, T-mi, velocity, v(f)) and the conditions for transition and portray these in the plane T-m, vs Lev(f) in a long once-through reactor. We show that these maps predict well the behavior in loop reactors. (C) 2017 Elsevier B.V. All rights reserved.