Adsorption process is considered to be the most promising alternative for the CO

2

capture to the traditional energy-intensive amine absorption process

and the development of feasible and efficient CO

2

adsorbents is still a challenge. In this work

the NiO@USY (ultrastable Y) composites with different NiO loadings were prepared for the CO

2

adsorption using Ni(NO

3

)

2

as the precursor. The composites were characterized by X-ray photoelectron spectroscopy

X-ray diffraction

nitrogen adsorption–desorption test

scanning electron microscopy analysis

and thermogravimetric analysis

and were evaluated for the CO

2

adsorption capacity

CO

2

/N

2

adsorption selectivity and CO

2

cycle adsorption capacity. The characterization results show that after the activation at 423 K

the Ni(NO

3

)

2

species were well dispersed into the surface of zeolite USY

and after the further activation at 823 K

Ni(NO

3

)

2

could be converted into highly dispersed NiO. The adsorption results show that the presence of the active component NiO plays an important role in improving the CO

2

adsorption performance

and the NiO@USY composite with a NiO loading of 1.5 mmol·g

-1

USY support displays a high adsorption capacity and adsorption selectivity for CO

2

and shows a good cycle stability. In addition

the Clausius–Clapeyron equation was u

sed to evaluate the isosteric heat of adsorption of CO

2

on the NiO(1.5)@USY composite

and the heat of adsorption was 17.39–38.34 kJ·mol

-1

.