Manganese-Modified Fe3O4 Microsphere Catalyst with Effective Active Phase of Forming Light Olefins from Syngas

A manganese-modified Fe3O4 microsphere catalyst was developed, which effectively converts the syngas to light olefins (C-2-C-4) with selectivity up to 60.1% in all hydrocarbon products. This nonporous catalytic material with fine dispersed manganese contributes to clarifying the different role of iron carbides by solely modifying the carburization of the catalysts and reducing the diffusion resistance of products. Combining various characterization results, including XAFS and Mossbauer spectroscopy, it is found that the electronic state of surface carbonaceous species was affected by the Mn promoter, leading to the formation of special iron carbide (theta-Fe3C), and the reactivity for light olefins formation was highly dependent on the content of theta-Fe3C.