A catalyst bed comprising a ceramic or metallic foam comprising one or more NOx reduction catalysts is described. A method for reducing the concentration of NOx in a dust containing gas stream comprising: a) passing a first gas stream containing NOx into a contacting zone; b) contacting the first gas stream with a ceramic or metallic foam catalyst bed having one or more flow paths through the catalyst bed wherein the ceramic or metallic foam comprises a NOx reduction catalyst to produce a second gas stream with a reduced NOx concentration; and c) passing the second gas stream out of the contacting zone wherein the first gas stream has a dust concentration of at least 5 mg/Nm3 and the pressure drop of the foam catalyst bed increases by 300% or less relative to the initial pressure drop of the foam catalyst bed due to dust accumulation, measured under the same conditions is also described.