Hydrogenation of Carbon Dioxide over Co-Fe Bimetallic Catalysts
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Gnanamani, Muthu Kumaran
Hamdeh, Hussein H.
Shafer, Wilson D.
Hopps, Shelley D.
Thomas, Gerald A.
Davis, Burtron H.
Muthu Kumaran Gnanamani, Gary Jacobs, Hussein H. Hamdeh, Wilson D. Shafer, Fang Liu, Shelley D. Hopps, Gerald A. Thomas, and Burtron H. Davis. Hydrogenation of Carbon Dioxide over Co–Fe Bimetallic Catalysts. ACS Catalysis 2016 6 (2), 913-927 DOI: 10.1021/acscatal.5b01346
A series of Co-Fe bimetallic catalysts was prepared, characterized, and studied for the hydrogenation of carbon dioxide. The catalyst precursors were prepared via an oxalate coprecipitation method. Monometallic (Co or Fe) and bimetallic (Co-Fe) oxalate precursors were decomposed under a N-2 flow at 400 degrees C and further pretreated under a CO flow at 250 degrees C. The catalysts (before decomposition of the oxalates or after activation) were characterized by BET, TGA-MS, X-ray diffraction, CO-TPR, SEM, HR-TEM, and Mossbauer spectroscopy techniques. The hydrogenation reaction of CO2 was performed using Co-Fe bimetallic catalysts pretreated in situ in a fixed-bed catalytic microreactor operating in the temperature range of 200-270 degrees C and a pressure of 0.92 MPa. With increasing Fe fraction, the selectivity to C-2-C-4 for Co-Fe catalyst increased under all operating conditions. The alcohol selectivity was found to increase with increasing iron content of the Co-Fe catalyst up to 50%, but then it dropped with further addition of iron. Among the three different activation conditions, the CO pretreated Co-Fe (50Co50Fe) catalyst exhibited a much lower selectivity for methane. Addition of 1 wt % Na or 1.7 wt % K to 50Co50Fe catalyst increases its olefinic (C-2-C-4) and oxygenate selectivities.
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