Enhanced low-temperature activity of CO2 methanation over highly-dispersed Ni/TiO2 catalyst

Abstract

The sustainable development of carbon recycling has attracted considerable attention from the viewpoint of the environment and resources. Herein, Ni nanoparticles (NPs) immobilized on a TiO₂ support were synthesized via a deposition–precipitation method followed by a calcination–reduction process (denoted as Ni/TiO₂-DP), which can be used as a promising heterogeneous catalyst towards CO₂ methanation. Transmission electron microscope (TEM) images show that Ni NPs are highly dispersed on the TiO₂ surface (particle size: 2.2 nm), with a low Ni–Ni coordination number revealed by the hydrogen temperature programmed desorption (H₂-TPD) and extended X-ray absorption fine structure (EXAFS) techniques. Moreover, the catalyst with a Ni loading of 15 wt% exhibits excellent catalytic behavior towards CO₂ methanation (conversion: 96%; selectivity: 99%) at a reaction temperature as low as 260 °C. The good dispersion of Ni NPs with large unsaturation facilitates a high exposure of active sites, which accelerates the formation of surface-dissociated hydrogen and the subsequent hydrogenation removal of surface nickel carbonyl species, accounting for the resulting enhanced low-temperature catalytic performance.