A La-promoted Ni/MgAl2O4 catalyst with superior methanation performance for the production of synthetic natural gas

Production of synthetic natural gas (SNG) has received increasing attention due to the clean nature and unbalanced reserve of natural gas. One of the technical bottlenecks for SNG production is the lack of feasible catalyst for CO methanation process. Herein, Mg-Al mixed oxides were prepared as supports by the co-precipitation method and La promoter was subsequently introduced by the co-impregnation method for Ni-based methanation catalysts. The initial activity of the Ni/Mg-Al catalysts depended on molar ratio of Mg/Al. The Ni/ MgAl2O4 catalyst exhibited the best activity among the catalysts with various Mg/Al molar ratios (2/1, 1/1, 1/2, 1/3). Enhanced low-temperature activity and improved high-temperature stability were realized on the La-promoted Ni/MgAl2O4 catalyst. The Ni-La/MgAl2O4 catalyst possessed CO conversion of 95.1% at 270 degrees C and remained stable for 100 h at 550 degrees C under ambient pressure at a WHSV of 72 000 ml/(h gcat). The effect of La promoter on the catalytic performance of the Ni/MgAl2O4 catalyst was elucidated by N-2 sorption, XRD, TEM, H-2-TPR, H-2 pulse chemisorption, TG/DSC, and CO2-TPD characterizations. The obtained results demonstrated that the enhanced low-temperature activity was related to reduced size of Ni nanoparticles and increased reducibility of the catalyst. The improved high-temperature stability was associated with better sintering- and coke- resistance properties induced by stronger metal-support interactions and increased basic sites respectively. The present work suggests La-promoted Ni/MgAl2O4 catalyst as a promising candidate for efficient SNG production from synthesis gas.