Abstract
In recent years, global warming caused by CO2 emissions had been recognized as an urgent problem. For the fixation of CO2 emitted from industrial sources, various chemical processes for converting CO2 into valuable chemical compounds have been attempted. We investigated catalytic behavior of iron in CO2 hydrogenation with and without a ruthenium component. Calcined iron-based catalysts were reduced by H2 and characterized by XRD, BET surface area and CO2, CO and C2H4 temperature-programmed desorption (TPD), and tested for CO2 hydrogenation. The product distributions for catalysts with and without the ruthenium component were also compared. Fe-K/γ-Al2O3 exhibited higher methane (16 mol%) and C2-C4 selectivity (39.6 mol%) than Fe-Ru-K/γ-Al2O3. The main products obtained with Fe-Ru-K/γ-Al2O3 were higher hydrocarbons such as C5+ hydrocarbons. For Fe-Ru-K/γ-Al2O3, the product distribution followed the Anderson-Schultz-Flory (ASF) distribution. However, in the case of Fe-Ru-K/γ-Al2O3, the hydrocarbon distribution deviates from the ideal ASF distribution. It is concluded that the readsorption rates of the primary hydrocarbon product increase exponentially with chain length in the ruthenium promoted catalytic system. The behavior of catalysts with and without the ruthenium will be explained by the CO2-, CO- and C2H4-TPD profiles. In this study, it was confirmed that ruthenium component promoted the readsorption ability of α-olefin, and then the chain length of hydrocarbon is higher. In addition, the microcrystalline wax produced in CO2 hydrogenation was a high-crystalline and olefin-rich hydrocarbon.
