A catalyzer for burning part of a gaseous fuel/oxidant mixture, in particular for a burner of a power plant installation, has catalytically active channels and catalytically inactive channels and at least two sectors are arranged consecutively in the main flow direction. The sectors include a first sector defining an inlet sector and at least one following sector that includes one or more of a mixing sector arranged downstream from the inlet sector and an outlet sector. Further, the catalyzer has one or more of a smaller flow resistance in the inlet sector than any following sector, a higher catalytic activity in the inlet sector than any following sector, a plurality of holes in the mixing sector oriented transversely to the main flow direction and through which adjoining channels communicate, and a swirl generator in the outlet sector that provides a swirl to a gas mixture flowing through the outlet sector.