In CO2 sources, such as flue gas, the presence of moisture and oxygen is unavoidable. FeCrCu-K supported on hydrotalcite has been used for ICCU-RWGS. (https://doi.org/10.1016/j.jcou.2016.04.003). The dual functional materials were prepared by simple wet impregnation. The experiments were carried out under 5.8%-9.5% CO2 while the reaction temperature varied between 450 and 550 °C. In addition, the amount of materials for each test was around 1 g and the particle size was between 200 and 300 um. As shown in the following figure, moisture and oxygen have clear impacts on the ICCU-RWGS performance. In terms of the efficiency of CO2 capture, the presence of moisture or oxygen reduced CO2 capture efficiency; however, this was only obvious at higher CO2 concentrations. Nevertheless, CO2 conversion was reduced with the addition of moisture and oxygen under all CO2 concentrations. The selectivity of CO was enhanced in the presence of moisture and oxygen. It is noted that these conditions have a significant impact on CO2 conversion, which is reduced from 80% to around 40%.
“Figure – CO2 capture efficiency, CO2 conversion, and CO selectivity as a function of (A) CO2 concentration (5.8–9.5%) at 450 °C and (B) reaction temperature with 5.8% CO2. Gas composition—Capture phase: CO2 diluted in nitrogen (ideal condition), CO2 diluted in nitrogen saturated with 4% of water vapour (effect of water), CO2 diluted in nitrogen with 4% of oxygen (effect of oxygen) and CO2 diluted in nitrogen with 5% of oxygen and 4% of water (realistic condition). Gas hourly space velocity (GHSV)—1620 mL gcat−1 h−1. Reduction phase: Pure hydrogen with GHSV of 3900 mL gcat−1 h−1. The CCR period length was 215 s, i.e. 107.5 s for CO2 capture and reduction phase.”