Carbon Dioxide Methanation Performance On Ni-based Catalyst

CO₂ hydrogenation to methane can not only realize the recycling of carbon resources,but also effectively alleviate the contradiction between natural gas supply and demand.Furthermore,the introduction of PtG?Power-to-Gas?technology has made the CO₂ methanation a more widespread concern.The key technology to improve the efficiency of CO₂ methanation reaction is the development of high-efficiency catalysts.In view of the poor low-temperature performance of Ni-based catalysts,the preparation and modification of different types of Ni-based catalysts have been studied in this paper.Among the Ni/SiO₂ catalysts synthesized by different methods,Ni/SiO₂-HS prepared by hydrothermal synthesis method exhibited the best catalytic activity.The addition of TiO₂ to Ni/SiO₂-HS improved the Ni dispersion and the amount of weak basic sites on the catalyst.Furthermore,the presence of Ti⁴⁺/Ti³⁺redox pairs increased the density of electron clouds surrounding the Ni atoms that facilitated the CO₂activation.Thus,the activity of catalyst was significantly improved.La-promoted Ni/Mg-Al catalysts were synthesized by urea homogeneous precipitation method.It was found that La can increase the Ni dispersion,reduce the Ni particle size and increase the amount of moderate basic sites,thus effectively improving the low-temperature activity of catalyst.The catalyst exhibited the best catalytic activity when the La content is 5 wt%.On this basis,the effect of the preparation method on the structure and catalytic activity of the catalyst was investigated.It was found that the catalyst prepared by the urea homogeneous precipitation method has more Ni active sites and larger CO₂ adsorption capacity,exhibiting better low-temperature performance.Finally,the Ni loading of the catalyst was optimized and the catalyst exhibited the best activity when the Ni loading is 20 wt%.The Ni-based catalysts supported on different supports were synthesized using citric acid complex method.It was found that Ni/ZrO₂ catalyst showed the best catalytic activity.On this basis,the synthesis condition of the catalyst was optimized.When the molar ratio of citric acid to metal ions is 3,the catalyst exhibited the best activity owing to the highest Ni dispersion,the largest Ni surface area and an appropriate metal-support interaction.