アンモニアによる還元脱硝におけるV₂O₅/TiO₂触媒の活性におよぼすアルカリ土類金属塩付着の影響

抄録

The de activation on a V₂O₅/TiO₂ catalyst with deposited alkaline earth metal salts in the reduction of NO with NH3 and the regneration of the de activated catalyst were investigated. Alkaline earth metal salts (CaSO₄, CaCl₂, CaCO₃, Ca (NO₃) ₂, MgSO₄, MgCl₂, MgCO₃, Mg (NO₃) ₂) were deposited on the V₂O₅/TiO₂ catalyst (average diameter 1.0mm) by an impregnation method. Measurements were made in a flowtype packed bed reactor under atmospheric pressure at 350°C, the inlet gas was a mixture of NO (500ppm), SO₂ (0, 500ppm), NH₃ (500ppm), O₂ (5%), H₂O (10%), and N₂, and the total flow rate was 1000 Ncm³/min (sv: 6×10⁴h^-1).
The following results and informations were obtained:
1) In the reduction of NO under the absence of SO_x, the degree of de activation was remarkably affected by the kind of salts deposited. The degree of de activation with deposition of chlorides, carbonates and nitrates was large, and that of sulfates was very small.
2) In the reduction of NO under the presence of SO_x, the effect of the salts except MgCl₂ on the degree of de activation was not almost found.
3) The de activation was mainly caused by the reaction of alkaline earth metal salts with V₂O₅/TiO₂ catalyst, leading to the formation of an inactive oxide complex.
4) The de activated catalyst was not regenerated by a washing procedure with water.