PURPOSE: To provide a catalyst for purifying nitrogen oxide high in denitrating property and good in durability, obtained by mixing composite oxide comprising Ti, Si and Zr, V oxide, W oxide and Sn oxide in a specific ratio.
CONSTITUTION: A catalyst comprising at least one kind of 73W95wt% composite oxide (component A) selected from a two component composite oxide comprising Ti and Si or Ti and Zr or a three component composite oxide comprising Ti, Si and Zr, 0.3W3wt% V oxide (component B), 3W12wt% W oxide (component C) and 0.5W10wt% Sn oxide and/or Sn sulfate (component D) and having an Sn/W atomic ratio of 0.1W3.0 is constituted. In this case, the component A comprises, on the basis of the mol% of oxide, 40W95% Ti oxide and 5W60% Si and/or Zr oxide. From this composition, a catalyst low in SO2 oxidizing activity is obtained.
KOBAYASHI MOTONOBU
SAITOU KOUICHI
NANBA TASUKU
ONO TETSUTSUGU
