(536m) Exploring LaFeO3 oxygen Carriers for Reactivity Enhancement through Structural Changes in Chemical Looping Partial Oxidation System
AIChE Annual Meeting
Wednesday, November 16, 2022 - 3:30pm to 5:00pm
In this work, LaFeO3 nanoparticles were synthesized for carrying out the CL-POX reaction by embedding them in mesoporous SBA-15 support (LaFeO3@SBA-15). For comparison micro-sized LaFeO3 sample impregnated on SiO2 support (LaFeO3@SiO2) was also synthesized. Thermogravimetric experiments (TGA) employing methane as reducing gas showcased that LaFeO3@SBA-15 maintained stable performance over 15 redox cycles with nearly 1000% improvement in reaction rate compared to LaFeO3@SiO2. In addition, characterization techniques such as X-ray diffraction (XRD), nitrogen physisorption, and high-resolution transmission electron microscopy (HR-TEM) were used to investigate this dramatic increase in reaction rate. The analysis revealed that LaFeO3 forms a different crystal structure when embedded in SBA-15 as opposed to SiO2. This can be attributed to the mesoporous, tubular, and ordered structure of SBA-15 which enabled the formation of nano-scaled particles and stabilized a more active LaFeO3 crystal structure. To corroborate the experimental results and explore the reaction mechanism over the different crystal structures, atomistic level-based density functional theory calculations were carried out. The findings from this study provide vital insights into the role of crystal structure in reaction kinetics and thus can be leveraged to develop highly active chemical looping oxygen carriers.