The present device is a fluid bed regenerative thermal oxidizer configured to minimize dead spaces within it and eliminate the need for complex valve systems, which are typically required to move treated and untreated air across fixed beds. The present device can be a fluid bed regenerative thermal oxidizer comprising a vertical stack having a combustion chamber near its interior center and desorber shelves located within the vertical stack above the combustion chamber and adsorber shelves located within the vertical stack below the combustion shelves. Ceramic spheres can be used as heat sinks that flow from the desorber shelves, around the combustion chamber and onto the adsorber shelves and then back to the desorber shelves. In this way heat from the combustion can be captured by the heat exchange material on the desorber shelves and released to preheat untreated air on the adsorber shelves.