| 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. |