CATALYST SYSTEMS

A monolithic structural catalyst body catalytically active for the selective catalytic reduction of nitrogen oxides comprises an outer peripheral wall and a plurality of inner partition walls arranged within the outer peripheral wall. The walls are formed of a screened and extruded uniform chemical composition which comprises 50-99% by weight an inorganic oxide composition and at least 0.1% by weight vanadium pentoxide, tungsten oxide, molybdenum oxide and/or mixtures thereof and comprises reinforcement agents. The inner partition walls have an average thickness of less than 0.22 mm. The catalyst body has a hydraulic diameter greater than or equal to 100 mm and has a transverse compressive strength of at least 147 kPa. The catalyst body may be used to reduce the nitrogen dioxide content of a combustion flue gas flowing there through.