A turbogenerator system including a recuperator and a catalytic combustor employs a preheater located between the turbine outlet and the recuperator low-pressure inlet to heat the low-pressure turbine exhaust. Heat from the turbine exhaust is transferred to a cool high-pressure flow in the recuperator. A recirculation loop employs valves downstream of the recuperator low-pressure outlet to divert the recuperator low-pressure exhaust into the compressor to be recirculated through the recuperator high-pressure side and the catalytic combustor. Reduced start-up times and emissions are achieved by raising the combustor catalyst to its light-off temperature in a shorter period of time.
 The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of the Flex Energy Contract NO. 500-99-030ZDH-0-29047-03 awarded by the Department of Energy.