Effect of Pr Promotion\non Co-Based Catalysts for Fischer–Tropsch\nSynthesis to Olefins

Fischer–Tropsch synthesis to olefins (FTO) from\nsyngas with\nlow CO<sub>2</sub> selectivity achieves great attention but still\nremains challenging. Herein, Pr-promoted metallic Co catalysts were\napplied to the FTO reaction, and the promotional effect was investigated\nin detail. All Pr-promoted catalysts displayed higher olefin selectivity\nand lower methane selectivity compared with the unpromoted Co-based\ncatalysts. Moreover, the CO<sub>2</sub> selectivity was significantly\nsuppressed, owing to the low intrinsic activity of metallic Co sites\nfor the water–gas shift reaction (WGSR). The optimal Pr loading\nwas found to be 10 wt %, which resulted in a high olefin selectivity\nof 44.1% and a low CO<sub>2</sub> selectivity of 1.1%. The structural\ncharacterization revealed that the addition of Pr altered the electronic\nstate of Co species, leading to enhanced CO adsorption and a low H/C\nratio on the catalyst surface. Furthermore, secondary hydrogenation\nactivity was also inhibited by adding the Pr promoter, which is favorable\nfor olefin production.