Suitability evaluation of steam-reforming catalyst for DME-fueled chemically recuperated gas turbine system

Dimethyl ether (DME), which is attracting attention as an alternative fuel for versatile use, has been tried to apply to the Chemically Recuperated Gas Turbine (CRGT), since DME steam-reforming that occurs at temperatures below 350°C with endothermic reaction is suitable for chemical heat recovery and leads to enhancement of power generation efficiency and power output. One of important concerns for the DME-fueled CRGT is related to catalyst reactions in the heat recovery reformer that is a key component of the system because exothermic reactions such as methanation and CO shift disturb the chemical heat recovery. Almost 30 kinds of precious metal-based catalyst were screened using the pressurized reformer to find the most suitable candidate for the CRGT from the viewpoint of LHV increase of the reformed gas. The selected candidate of catalyst was also tested with various temperature, steam/DME molar ratios (S/DME) and pressures. The result indicated that T=450°C and S/DME=3.5 was an appropriate condition for the reasons of the balance between endothermic and exothermic reaction rates and carbon deposition. The catalyst was also available for the pressure range up to 2.1 MPa in a MW class GT system without significant decrease of chemical heat recovery.