(582ci) Calcium and Manganese-Doped Lanthanum Iron Perovskite Oxides As Candidate Redox Materials for CO2 Reduction to CO

Carbon dioxide is the sole source for renewable carbon-based energy on Earth. CO₂ processing into fuel production intermediates such as CO, a major component of synthesis gas, is thermodynamically challenging and requires catalytic materials capable of redox cycling. Perovskite-type oxides in particular have shown promise in efficiently converting CO₂ to CO in the reverse water gas shift chemical looping process (RWGS-CL) by retaining nonstoichiometric lattices as previously demonstrated by our group. Metals of greater Earth abundancy are required to decrease both conversion temperature and material cost to make large scale CO₂ to fuels processes more economically feasible for commercial industry. For instance, calcium is capable of replacing previously used elements such as strontium or barium while improving catalytic activity. Metals such as Ca and Mn may be tailored into the perovskite structure of LaFeO₃ to simultaneously improve CO production rates and decrease rare metal content. Density functional theory calculations also conducted by our group suggest that compositional optimization of La_XCa_1-XFe_YMn_1-YO₃ (LCFM) will further increase CO₂ convertibility of the alloy material. Currently, La_0.6Ca_0.4MnO₃ demonstrated a total CO yield of 1240 μmoles/g cat while that of La_0.6Ca_0.4Fe_0.4Mn_0.6O₃ was 970. However, a peak CO production rate of 160 μmoles/g cat/min was achieved with the latter species at 500 °C as opposed to 60 μmoles CO/g cat/min at 550 °C by the conventional La_0.75Sr_0.25FeO₃ perovskite. These LCFM materials will be tested in temperature programmed experiments monitored by mass spectrometry to observe the effects of doping on ideal reaction temperatures and characterized via several techniques including X-Ray diffraction and BET analysis for crystalline structure and surface area.