Enkhsaruul Byambajav

Title : Production of light hydrocarbons (C2-C4) by hydrogenation of CO2 using Co-K/?-Al2O3 catalysts with additional metal promoters (Ba, La, Ce) and combined supports (Y2O3, TiO2)

Abstract:

In this research work, we obtained C₂-C₄ hydrocarbons as a product of the Fischer-Tropsch synthesis (FT-CO₂) by converting CO₂ using Co-K/?-Al₂O₃ catalysts. The catalysts were enhanced with 1% Ba, La, Ce or 0.5-3% Ce promoters, respectively. Moreover, 10% Y₂O₃ or 10%TiO₂ was added to the ?-Al₂O₃ support, respectively. Effect of the promoter and the support doping on CO₂ conversion and C₂-C₄ selectivity was inverstigated in FT-CO₂ synthesis.

The catalysts were prepared using the incipient wetness impregnation method, and characterized by X-ray diffraction analysis, Temperature-programmed hydrogen reduction, and CO₂ desorption measurements. Catalytic activity of the catalysts was evaluated in a fixed-bed reactor at 350°C, 3 atm, and H₂:CO₂=3:1 molar ratio with a total volume rate of 3000 h^-1.

At 350ºC, the addition of promoter metals to the catalysts increased catalyst activity. The Ce promoted Co-K/?-Al₂O₃ catalyst increased the C₂-C₄ yield by 10.67%. However, the catalyst activity decreased when the Y₂O₃, TiO₂ was added into the ?-Al₂O₃ support. At 350ºC, the Co-K-1Ce/?-Al₂O₃ catalyst showed the highest activity in the FT-CO₂ synthesis. With this catalyst, CO₂ conversion, C₂-C₄ yield and C₂-C₄ hydrocarbon selectivity were reached 44.90%, 14.91%, and 37.17%, respectively. TPR results of the Co-K-1Ce/?-Al₂O₃ catalyst showed the creation of much active sites due to the interaction between metal and support, leading to an increase in selectivity towards light hydrocarbons. Also it was known by CO2-TPD analysis that the interaction between metal catalysts and support enhanced the CO₂ activation over the Co-K-1Ce/?-Al₂O₃ by increasing the medium strength basic sites. Futhermore, additional supports such as Y₂O₃ and TiO₂ increased the CO yield by the reverse-water gas shift reaction in FT-CO₂ synthesis.

The addition of Ce as the promoter to the Co catalyst was found to be the most effective way for enhancing the catalytic activity, while the addition of Y₂O₃ and TiO₂ to the ?-Al₂O₃ support did not show significant improvement in catalyst performance for the FT-CO₂ synthesis.

Biography:

Dr. Enkhsaruul Byambajav studied at the Tohoku University, Japan and graduated her PhD course in 2004. Since then, she is teaching at the National University of Mongolia. She was promoted as a full professor the National University of Mongolia in 2020. Now she is supervising a laboratory of Clean energy technology development in the university. She has published more than 20 research articles in WoS-JCR journals.