The acidic properties of aluminum phosphate (AlPO

4

-5) solid acid catalyst were characterized by temperature programmed desorption (TPD) of ammonia (NH

3

)

n-propylamine (n-C

3

H

7

NH

2

)

iso-propylamine [(CH

3

)

2

CHNH

2

]

and n-dipropylamine [(C

3

H

7

)

2

NH

]

separately

and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst

the acid amount characterized by NH

3

-TPD decreased

however

it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic performance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH

3

as adsorbate

respectively

which indicated NH

3

was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength o

n the surface exhibited the better catalytic performance and stability.