Use of catalyst and method of removing aldehydes

A method of removing one or more aldehydes from a carrier fluid comprising ambient air, the method comprises contacting the carrier fluid comprising one or more aldehydes with a catalyst comprising manganese IV oxide and/or cryptomelane. The aldehyde may comprise at least two carbon atoms up to six carbon atoms. The catalyst can comprise a foam or metal support on or in which the manganese IV oxide and/or cryptomelane is supported. The catalyst may comprise a binder including alumina or a polymer. The carrier fluid preferably contacts the catalyst at a temperature of at least 10˚C to 100˚C. Advantageously cryptomelane is effective at removing longer chain aldehydes, such as propanal and crotanaldehyde, from an air flow, at relatively low temperatures while manganese IV oxide is effective at removing aldehydes such as, acetaldehyde from a stream of air at relatively low temperatures.