Enhanced CH4 selectivity for CO2 methanation over Ni-TiO2 by addition of Zr promoter

• Published in: Journal of environmental chemical engineering 2022-06, Vol.10 (3), p.107710, Article 107710
• Main Authors: Makdee, Ammarika, Kidkhunthod, Pinit, Poo-arporn, Yingyot, Chanapattharapol, Kingkaew Chayakul
• Format: Article
• Language: English
• Subjects: CO2 methanation; Electron movement; Metal-support interaction; Zr incorporation into TiO2
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2022.107710

TiO2 and 10 wt%Ni-ZrxTi1−xO2 (x = 0, 0.1, 0.15, and 0.2) catalysts were synthesized and used for CO2 methanation reaction. The catalyst with 10 mol% Zr addition (10 wt%Ni-Zr0.1Ti0.9O2) exhibited the highest CO2 conversion and CH4 selectivity with highly stable property. The role of Zr addition on enhancing CO2 methanation reaction rate was to tune the electronic property of Ni species by electron transfer from Zr to Ni valence state. From the donating effect of Zr, an appropriate metal-support interaction was then improved which led to higher dispersion of Ni species on catalyst surface which was beneficial to the adsorption of H2 molecules. Moreover, Zr addition also improved the basicity of the catalyst, which can also promote the adsorption of CO2. Therefore, an appropriate H2 and CO2 adsorption ability can enhance catalytic activity. The effect of tuning electronic properties by Zr addition on enhancing the catalytic performance resulted from lowering of C-O bonding dissociation barrier. Upon CO intermediate was adsorbed on Ni electron rich site, the electron of valence d state of Ni was transferred to π* anti-bonding of CO molecule and the C-O bonding was then weakened and easily dissociated to carbon and oxygen to further hydrogenation and formed products. [Display omitted] •The interaction between NiO and TiO2 was tuned by Zr addition in the TiO2 lattice.•The Zr addition in the TiO2 lattice promoted the catalyst basicity.•The electron movement from Zr to Ni leading to strong Ni-C and weak C-O.•The weakened C-O bonding resulted in easily CO dissociation to produce products.