Highly dispersed and stable Ni nanoparticles confined by MgO on ZrO2 for CO2 methanation

To improve the catalytic activity of CO 2 methanation at low temperature, a series of Ni/ZrO 2 catalysts with different Ni loadings were prepared by citrate complexing method. Based on the optimal Ni loading of 6 wt%, a certain amount of MgO was doped to improve the thermal stability of Ni/ZrO 2 catalyst. When Ni/Mg molar ratio was 4, there was the best performance, getting as high as 90% CO 2 conversion and nearly 100% CH 4 selectivity at 250 °C, 0.1 MPa and a WHSV of 15,000 ml g −1  h −1 , and the equilibrium CO 2 conversion was obtained at 300 °C. XRD , BET, TPR, CO 2 -TPD, H 2 -TPD, XPS , TG and TEM were conducted to investigate the reason of high activity of Ni/ZrO 2 catalyst at low temperature and the effect of doping MgO. Results suggested that highly dispersed Ni nanoparticles are responsible for the excellent catalytic activity. MgO can effectively improve stability of Ni-based catalysts by the confinement effect. Meanwhile, it is also found that there are little improvements on catalytic activity after doping MgO, and the TOF of catalysts with different MgO doping is basically the same, indicating CO 2 can be efficiently adsorbed and activated on the monoclinic ZrO 2 , and MgO do not contribute to the intrinsic activity.