Insights into the regulation of FeNa catalysts modified by Mn promoter and their tuning effect on the hydrogenation of CO2 to light olefins

In situ XRD, XPS and TPSR were used to investigate the effect of Mn promoter on the surface element distribution of FeNa and direct evidence for the Mn promoter tuning the product distribution were obtained. The enrichment of Mn promoters leads to the increasing amount of the Fe species near the Mn promoter on the surface, which was confirmed to be the strong adsorption centers for CO2 and consequently decreased the conversion of CO2. The ability of H2 adsorption over iron carbides increased with the increasing content of Mn promoters from 0.5% to 3.0%, which is possibly associated with prohibition of hydrogenation of carbon species to paraffins.