Hydrogenation of CO 2 to methane is a feasible solution to the growing global environmental and energy challenges. Nickel-based catalysts are efficient and cost effective for CO 2 methanation. Hernin, we synthesized Mn-promoted Ni/Al 2 O 3 catalysts with facilitated CO 2 methanation and elucidated the crucial role of Mn. After Mn doping, NiMn/Al 2 O 3 catalysts showed improved NiO dispersion. Subsequently, H 2 reduction and CO 2 methanation treatments resulted in reduction of NiO and MnO 2 into Ni and MnO, and incorporation of Ni 2+ into MnO lattice, forming NiMnO x and creating numerous Ni-NiMnO x interfaces. The abundant oxygen vacancies from NiMnO x could enhance CO 2 activation. Moreover, oxygen vacancies at the interface also promote electron transfer from Ni and MnO, leading to electron-poor Ni nanoparticles and thus significantly promoting the *CO methanation. Ultimately, the electron-poor Ni nanoparticles and abundant oxygen vacancies at the Ni-NiMnO x interface jointly facilitate CO 2 methanation.
Chen Yiming,Hou Zhanggui,Wang Chuan,Ma Xin,Yang Hong,Wang Wen,Zhou Ling,Zhang Yi
As well known, the industrial methanation process needs highly active and stable catalysts obtained from cheap and abundant elements. In this work, we propose a high-loaded Ni/Al 2 O 3 catalyst promoted by manganese. Among them, the 20Ni2Mn/Al 2 O 3 catalyst exhibits the best CO 2 conversion (90.5%) and excellent methanation stability at 250 °C. In addition, the roles of the Mn promoter on CO 2 conversion and selectivity were investigated in detail. The features of natural and promoted catalysts are described through XRD, XRF, BET, TEM, H 2 -TPR, CO 2 -TPD, and operando DRIFTS techniques. Based on various characterization results, the addition of Mn will greatly reduce the Ni particle size and improve the Ni dispersion on the alumina support. Furthermore, compared to the unpromoted catalyst, Mn promoted catalysts show better reducibility and have more medium basic sites. And these medium basic sites are favorable to the adsorption and activation of CO 2 . In-situ DRIFTS experiments for CO 2 methanation reveal that manganese could promote the monodentate carbonate hydrogenated to formate rapidly, which could be faster converted towards CH 4 , contributing to significantly improved activity of the Mn promoted Ni/Al 2 O 3 catalyst. Graphical Abstract
危险品化学品经营许可证（带存储）