Comparative study of CO and CO2 hydrogenation over supported Rh–Fe catalysts

The hydrogenation of CO, CO + CO2, and CO2 over titania-supported Rh, Rh–Fe, and Fe catalysts was carried out in a fixed-bed micro-reactor system nominally operating at 543 K, 20 atm, 20 cm3 min− 1 gas flow (corresponding to a weight hourly space velocity (WHSV) of 8000 cm3 gcat− 1 h− 1), with a H2:(CO + CO2) ratio of 1:1. A comparative study of CO and CO2 hydrogenation shows that while Rh and Rh–Fe/TiO2 catalysts exhibited appreciable selectivity to ethanol during CO hydrogenation, they functioned primarily as methanation catalysts during CO2 hydrogenation. The Fe/TiO2 sample was primarily a reverse water gas shift catalyst. Higher reaction temperatures favored methane formation over alcohol synthesis and reverse water gas shift. The effect of pressure was not significant over the range of 10 to 20 atm.