Process for treating dioxin-containing exhaust gas and composite catalyst composition for inhibiting generation of dioxin

A process for treating a dioxin-containing exhaust gas comprising:

• adding an iron compound catalyst comprising iron oxide particles or iron oxide hydroxide particles and having a catalytic activity capable of decomposing not less than 20% by weight of monochlorobenzene when 3.1×10−4 mol (50 mg) of iron oxide particles obtained by heat-treating said iron compound catalyst at 300° C. for 60 minutes in air is instantaneously contacted with 5.0×10−7 mol of monochlorobenzene at 300° C. at a space velocity of 150,000 h−1 in an inert gas atmosphere using a pulse catalytic reactor, into an exhaust gas having a temperature of 150 to 500° C. in the course of cooling between a downstream portion subsequent to a combustion chamber and a dust collector of a waste incinerator to contact the iron compound catalyst with the exhaust gas,
• the amount of said iron compound catalyst added being 0.01 to 2.5% by weight based on the weight of dry wastes incinerated per hour, and said iron oxide particles or said iron oxide hydroxide particles having an average particle size of 0.01 to 2.0 μm, a phosphorus content of not more than 0.02% by weight based on the weight of the particles, a sulfur content of not more than 0.6% by weight based on the weight of the particles and a sodium content of not more than 0.5% by weight based on the weight of the particles.