Laboratory tests of catalytic combustors with distillate fuel have achieved ultralow NOx formation at catalytic reactor exit temperatures and combustion efficiencies consistent with state-of-the-art gas turbine requirements. Concomitant with these features, however, are design limitations such as narrow turn-down range and unique reactor mounting requirements. This paper presents fully analyzed conceptual design solutions to these problems within the constraints of fixed geometry, full catalytic combustion over 80 percent of the turbine load range, and retrofit to an existing gas turbine. The combustor design incorporates (a) a gutter stabilized pilot burner downstream of the reactor for operation from ignition to full-speed no-load, (b) a segmented fuel-air preparation system for fuel staging of the reactor, (c) a reactor mounting system which accommodates thermal growth and start-up and shutdown transients, and (d) a graded cell reactor. These features were achieved while maintaining low reactor face velocities and system pressure drops.