Technology of methane combustion on granulated catalysts for environmentally friendly gas turbine power plants

The technology of methane combustion in small gas turbine catalytic combustors on alternative granulated catalysts with a low content of noble metals has been developed and studied. The operations of catalyst packages for environmentally clean combustion consisting of one-, two- or three catalysts with different chemical composition, shape and size of granules have been analyzed. The optimized design of a three-stage catalyst package with total height of 340 mm includes 40 mm of highly active Pd–Ce–Al2O3 at the entrance of the combustion chamber in the form of 7.5 mm × 7.5 mm × 2.5 mm rings; 240 mm of a basic catalyst based on Mn–hexaaluminate with the granules of the same form and size; and 60 mm of Pd–Mn–La–Al2O3 catalyst as 4–5 mm spherical granules at the exit of the combustion chamber. Such optimal design yielded methane combustion over 99.97% at Tinlet = 470–580 °C and oxygen excess coefficient 5.2–7.0. The emission levels were NOx < 1 ppm, CO < 10 ppm, HC < 10 ppm. The pressure drop across the catalyst package was less than 4% of the total pressure (1 bar).