Oxygen Storage Characteristics and Redox Behaviors of Lanthanum Perovskite Oxides with Transition Metals in the B-Sites
Yuanjie Jiang, Zhishan Li, Tao Zhu, Dongfang Li, Hua Wang, Xing Zhu
Abstract
Perovskites are typical oxygen storage materials that find many chemical, energy, and environmental applications. Lanthanum-based perovskite oxides represent a large family of oxygen carriers for chemical looping processes. Oxygen storage and redox behaviors are crucial for efficient activation of C–H/C═O, selective oxidation/combustion, heat management for chemical looping, or lattice oxygen-related reactions. The present work studied oxygen releasing/acquiring behaviors of lanthanum-based perovskite oxides with different B-site transition metals (Fe, Co, Ni, Cr, Mn, Al, Cu, and V) in CH 4 /CO/H 2 and CO 2 /O 2 by means of thermodynamic analysis, temperature programmed reduction/oxidation (TPR/TPO) experiments, and kinetics study. The oxygen release capacities obtained from H 2 -TPR followed an order of LaCoO 3 > LaNiO 3 > La 2 CuO 4 > LaVO 4 > LaMnO 3 > LaFeO 3 ≫ LaAlO 3 ≈ LaCrO 3, and all hydrogen-reduced perovskite oxides showed good regeneration ability in O 2 -TPO except LaNiO 3 due to the sintering of metallic Ni. Except inner properties of Al and Cr perovskite oxides, lanthanum-based perovskite oxides (Co, Ni, Cu, V, Mn, and Fe) were able to donate lattice oxygen for fuel oxidation, and the reducibility follows an order of H 2 > CO > CH 4 . In addition to O 2, CO 2 could fully or partially regenerate lattice oxygen for most H 2 -reduced perovskite oxides at higher temperatures above 700 °C and the H 2 -reduced LaFeO 3 could be oxidized with CO 2 starting at 500 °C. La 2 CuO 4, LaMnO 3, LaCoO 3, and LaNiO 3 might be suitable candidates for chemical looping air separation/combustion/selective hydrogen combustion at low temperatures (250–550 °C). LaFeO 3 is suitable for chemical looping partial oxidation of CH 4 /CO 2 splitting but with high reduction temperatures. This work provides a valuable reference for developing suitable oxygen carriers or redox catalysts for chemical looping or related processes.