METHOD FOR SUPPRESSING INCREASE IN SO2 OXIDATION RATE OF NOx REMOVAL CATALYST
AssigneeMitsubishi Heavy Industries, Ltd.
InventorsKatsumi Nochi, Masashi Kiyosawa
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Abstract
In a NOx removal catalyst used for removing nitrogen oxides in flue gas, when a silica (Si) component as an inhibitor that causes an increase in a SO2 oxidation rate accumulates on a surface of the catalyst, the silica component accumulating on the surface of the catalyst is dissolved, thereby regenerating the catalyst. Accordingly, the inhibitor such as the silica component covering the surface of the NOx removal catalyst can be removed, thereby enabling to provide a catalyst without having an increase in the SO2 oxidation rate of the regenerated NOx removal catalyst.
Claims8
A method for suppressing an increase in a SO2 oxidation rate of a NOx removal catalyst, comprising:
- an alkali treatment step at which an inhibitor, which causes an increase in a SO2 oxidation rate, is removed by washing with an aqueous alkaline solution, at a time of regeneration of the NOx removal catalyst;
- and
- an activation treatment step at which activation treatment of the catalyst is performed with an acidic aqueous solution, after the alkali treatment step, wherein
- a carrier of the NOx removal catalyst is titanium oxide, and the inhibitor is a silicon compound,
- an intensity ratio of titanium and silicon (Si/Ti intensity ratio) on a surface of the NOx removal catalyst is obtained, and
- when the Si/Ti intensity ratio exceeds a threshold of 0.1,
- the alkali treatment step and the activation treatment step are performed again.
(canceled)
Dependencies are inferred from the claim text.