Session: General Catalysis:

With the rising concerns regarding the detrimental effects of greenhouse gas emissions, the capture and utilization of CO₂ has drawn attention due to the molecule’s ability to be transformed into value-added chemicals. Hydrogenation of CO₂ into light olefins will not only contribute to efforts of alleviating the impacts of global warming, but also provide as a substitute for the diminishing supply of fossil fuels. However, such processes remain a challenge because CO₂ is known to be an extremely stable and inert molecule, its strong C-C coupling barrier requiring high amounts of energy input to break. In order to reap the benefits of CO₂ conversion, it is necessary to develop catalysts that demonstrate high levels of activity and selectivity toward light olefins. This work explores the catalytic performance of CO₂ hydrogenation to light olefins over CeO₂ supported bimetallic Fe-Co catalysts with varying mole ratios between Fe and Co. A series of CeO₂-supported catalysts with varying mole ratios between Fe and Co were synthesized using the solvent extraction impregnation method. CO₂ hydrogenation was tested through a flow bed reactor conditioned at atmospheric pressure and varying temperatures (275 °C, 300 °C, 350 °C) using an on-line gas chromatograph (GC) analysis. Catalyst testing data showed that a trend was observed for the catalysts with varying Fe/Co mole ratios, with the Fe₂Co₄-CeO₂ catalyst producing consistently high percentages for CO₂ conversion, C₂-C₃ olefin selectivity, and C₂-C₃ olefin yield. Bimetallic catalysts have been proven in our studies to generate higher light olefin selectivity and yield compared to monometallic catalysts. However, it is important to note that the loadings of each component and the mole ratio of metals in a catalyst play important roles in affecting catalyst performance. The catalysts were characterized by diffuse reflectance infrared Fourier-transformation spectroscopy (DRIFTS) and x-ray photoelectron spectroscopy (XPS).

Sanjaya Senanayake

Brookhaven National Laboratory

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