Fabrication of nickel oxide functionalized zeolite USY composite as a promising adsorbent for CO2 capture

Adsorption process is considered to be the most promising alternative for the CO₂ capture to the traditional energy-intensive amine absorption process, and the development of feasible and efficient CO₂ adsorbents is still a challenge. In this work, the NiO@USY (ultrastable Y) composites with different NiO loadings were prepared for the CO₂ adsorption using Ni(NO₃)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 CO₂ adsorption capacity, CO₂/N₂ adsorption selectivity and CO₂ cycle adsorption capacity. The characterization results show that after the activation at 423 K, the Ni(NO₃)₂ species were well dispersed into the surface of zeolite USY, and after the further activation at 823 K, Ni(NO₃)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 CO₂ 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 CO₂, and shows a good cycle stability. In addition, the Clausius–Clapeyron equation was used to evaluate the isosteric heat of adsorption of CO₂ on the NiO(1.5)@USY composite, and the heat of adsorption was 17.39–38.34 kJ·mol^-1.