Abstract: An olefin production device for producing an olefin from a raw material gas containing methane and oxygen includes a reactor containing: a first catalyst; and a second catalyst disposed downstream of the first catalyst in a flow direction of the raw material gas. The first catalyst is a catalyst in which a zirconium salt or carbonate of an alkali metal, an oxide of an alkaline earth metal, an oxide of one kind of lanthanoid element, a composite oxide containing a lanthanoid element, or a combination thereof is supported on a support. The second catalyst is a catalyst containing a tungsten oxide, phosphate, or carbonate of an alkali metal.

Abstract: A plant that consumes a reformed gas obtained by reforming a source gas including at least methane and carbon dioxide includes: a reforming device that includes a reforming catalyst for reforming the source gas and an electric power supply member for supplying electric power to the reforming catalyst and that supplies electric power to the reforming catalyst to reform the source gas; and a reformed gas consuming apparatus that consumes the reformed gas A reaction temperature of a reforming reaction of the source gas in the reforming device can be adjusted by adjusting a supply amount of a heating medium including exhaust heat generated due to consumption of the reformed gas in the reformed gas consuming apparatus to the reforming device when heat exchange between the source gas and the heat medium is performed in the reforming gas.