Methanation of carbon dioxide over Ni/CeO 2 catalysts: Effects of support CeO 2 structure

The CeO 2 , which were prepared by hard-template method, soft-template method, and precipitation method, were used as support to prepare Ni/CeO 2 catalysts (named as NCT, NCS, and NCP catalysts, respectively). The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). Hydrogen temperature-programmed reduction (H 2 -TPR) was also used to study the reducibility of the support nickel precursors. Moreover, CO 2 catalytic hydrogenation methanation was used to investigate the catalytic properties of the prepared NCT, NCS, and NCP catalysts. H 2 -TPR and XRD results showed that the NiO can be reduced by H 2 to produce metal Ni species, and the surface oxygen species existing on the surface of the support CeO 2 can also be reduced by H 2 to form surface oxygen vacancies. Low-angle XRD, TEM, and BET results indicated that the NCT and NCS catalysts had developed mesoporous structure and high specific surface area of 104.7 m 2 g −1 and 53.6 m 2 g −1 , respectively. The NCT catalyst had the highest CO 2 methanation activity among the studied NCT, NCS, and NCP catalysts. The CO 2 conversion and CH 4 selectivity of the NCT catalyst can reach 91.1% and 100% at 360 °C and atmospheric pressure. The NCP catalyst, which had low specific surface area and low porosity, performed less CO 2 conversion and higher CH 4 selectivity than the NCT and NCS catalysts till 400 °C.