Enhanced low-temperature catalytic activity for CO2 methanation over NiMgx/Na-HNTs: The role of MgO.

CO 2 methanation over Ni-based catalysts provides a promising way to address the energy crisis and the environmental problems caused by massive CO 2 emissions. Nevertheless, Ni-based catalysts still face the challenges of poor activity at low temperatures. Herein, a series of MgO-promoted Ni-based catalysts supported by HNTs (halloysite nanotubes) were successfully prepared to investigate the role of MgO in CO 2 methanation. Various characterization results demonstrated that introducing MgO can enhance metal-support interaction, resulting in generating finer and more stable metal particles. Meanwhile, MgO can also offer sufficient alkaline sites and oxygen vacancies for CO 2 activation. NiMg1.0/Na-HNTs exhibited the maximum CO 2 conversion (79.0%) and CH 4 selectivity (97.5%) even at 275 °C as well as outstanding long-term stability over 100 h reaction. Additionally, in situ DRIFTS suggested that the mechanism for CO 2 methanation in this work mainly followed the formate pathway, and introducing magnesium can accelerate to convert intermediates. Briefly, this study provides an efficient low-temperature catalyst for CO 2 methanation with potential industrial applications. [Display omitted] • The metal-support interaction is strengthened through introducing MgO. • MgO-modified Ni-based catalysts possess more basic sites and oxygen vacancies. • NiMg1.0/Na-HNTs exhibits 79.0% CO 2 conversion even at 275 °C. • NiMg1.0/Na-HNTs shows outstanding long-term stability over 100 h reaction. • The formates are the main intermediates over NiMg1.0/Na-HNTs. [ABSTRACT FROM AUTHOR]