The significant decrease of acid sites caused by alkali metal poisoning is the major factor in the deactivation of commercial V

2

O

5

-WO

3

/TiO

2

NH

3

-SCR catalysts. In this work

the solid superacid SO

4

2-

-TiO

2

modified by sulfate radicals

was selected as the catalyst support

which showed superior potassium resistance. The physicochemical properties and K-poisoning resistance of the V

2

O

5

-WO

3

/SO

4

2-

-TiO

2

(VWSTi) catalyst were carried out by XRD

BET

H

2

-TPR

NH

3

-TPD

XPS

in situ

DRIFTS and TG. The results pointed out that the introduction of SO

4

2-

significantly increased the NH

3

-SCR catalytic activity at high temperatures

with an exceptionally high NO

x

conversion over 90% between 275 ℃ and 500 ℃. When 0.5% (mass) K

2

O was doped on the catalysts

the catalytic performance of the traditional V

2

O

5

-WO

3

/TiO

2

(VWTi) catalyst decreased significantly

while the VWSTi catalyst could

still maintain a NO

x

conversion over 90% in the range of 300–500 ℃. The characterizations suggested that the support of SO

4

2-

-TiO

2

greatly increased the number of acidic sites

thereby enhancing the adsorption capacity of the reactant NH

3

. The results above demonstrated a potential approach to achieve superior potassium resistance for NH

3

-SCR catalysts using solid superacid.