Fabrication of highly efficient Ni/Al2O3 catalysts for the CO2 methanation reaction using atomic layer deposition technology

Abstract

Ni/Al₂O₃ catalysts with lower Ni loading have been fabricated using atomic layer deposition (ALD) technology and applied toward CO₂ methanation reaction. The Ni250/Al₂O₃-ALD catalyst exhibits a remarkably high CH₄ selectivity of 93.7 % and comparable CO₂ conversion of 90.2 % at 360 °C and 0.5 MPa when compared to Ni/Al₂O₃-IMP with an identical Ni loading prepared via the impregnation method. The abundant Ni-Al₂O₃ interface caused by the ultrahigh uniform dispersion of Ni provided an adequate number of adsorption sites for CO₂. More importantly, the single Ni atoms and small Ni nano-clusters (ca. 1.7 nm) strongly adsorbed the key CO* intermediates, which resulted in the highly selective production of CH₄ on the Ni250/Al₂O₃-ALD catalyst. Moreover, the higher concentration of oxygen vacancies and moderate basic sites also played pivotal roles toward enhancing the hydrogenation activity during the CO₂ methanation reaction. Our results provided a convenient strategy for the construction of promising Ni-based catalysts for CO₂ abatement.