Hydrogenation of Carbon Dioxide over Co-Fe Bimetallic Catalysts

Click on the DOI link to access the article (may not be free).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.This research was conducted with financial support from the Commonwealth of Kentucky