Abstract: A catalyst for decreasing the content of nitrogen oxides in flue gases. The catalyst contains at least one of the metals titanium, zirconium, vanadium, tungsten, molybdenum, or cerium in the form of one or more of their oxides combined with a silicate with a three-layer structure (three-layer silicate). The three-layer silicate is acid-activated while essentially retaining its crystalline layer structure. The three-layer silicate has a cation-exchange capacity of 30 mvals/100 g or more before acid activation. The acid activation lowers the concentration of interlayer cations and increases the BET surface at least 15% and preferably at least 50% in terms of the BET surface of the three-layer silicate before acid activation. The atomic ratio of the silicon in the acid-activated three-layer silicate to the metal in the oxide is from 0.2 and 50 and preferably from 0.4 to 25.

Abstract: A catalyst for decreasing the content of nitrogen oxides in flue gases. The catalyst contains at least one of the metals titanium, zirconium, vanadium, tungsten, molybdenum, or cerium in the form of one or more of their oxides combined with a silicate with a three-layer structure (three-layer silicate) comprising acid-activated pyrophyllite. The crystalline layer structure of the acid-activated pyrophyllite is essentially retained, while being not yet X-ray amorphous. The acid activation increases the BET surface area at least 15% and preferably at least 50% in terms of the BET surface area of the pyrophyllite before acid activation. The atomic ratio of the silicon in the acid-activated pyrophyllite to the metal in the oxide is from 0.2 and 50 and preferably from 0.4 to 25.

Abstract: A catalyst for decreasing the content of nitrogen oxides in flue gases. The catalyst contains at least one of the metals titanium, zirconium, vanadium, tungsten, molybdenum, or cerium in the form of one or more of their oxides combined with a silicate with a three-layer structure (three-layer silicate) which is or comprises talc. The three-layer silicate is preferably acid-activated while essentially retaining its crystalline layer structure and being not yet X-ray amorphous. The acid activation increases the BET surface area at least 15% and preferably at least 50% in terms of the BET surface area of the talc before acid activation. The atomic ratio of the silicon in the talc to the metal in the oxide is from 0.2 and 50 and preferably from 0.4 to 25.

Abstract: A catalyst for lowering the nitrogen oxide content of flue gases contains as the active component an acid-activated layer silicate, in particular of the smectite type, whose layered structure is to a large extent intact after the acid treatment.