Fuel tank inerting systems are described. The systems include a fuel tank having an inerting system flow path connected to the fuel tank. A catalytic reactor is arranged along the inerting system flow path configured to receive a reactant mixture of first reactant and a second reactant to generate inert gas. A condenser heat exchanger is arranged between the catalytic reactor and the fuel tank to cool an output from the catalytic reactor. A first ejector is configured to receive the first reactant and the second reactant and output the reactant mixture through an outlet. A second ejector is configured to receive an inert gas and the second reactant to output a mixture of the second reactant and the inert gas.