Selectively Etching Lanthanum to Engineer Surface Cobalt-Enriched LaCoO₃ Perovskite Catalysts for Toluene Combustion

Abstract

As appropriate alternatives to precious metals in volatile organic compound (VOC) combustion, La-based perovskites have attracted increasing attention due to their tunable structure and sintering-resistance capacity. Herein, chemically tailored surface Co-enriched LaCoO3 perovskite oxides (LCO) with abundant surface defects were successfully constructed via a facile selective acid-etching method, in which lanthanum located at the A-site was preferentially dissolved and exsolved cobalt opportunely dispersed on the surface of the perovskite. The unique LCO catalysts could enhance the electron transfer and facilitate the activation of oxygen molecules through the interface Co2+/Co3+ redox cycles. Among all as-synthesized LCO catalysts, the LCO-20 sample (LaCoO3 treated with 1 M HNO3 for 20 min) revealed the optimum catalytic performance (T 50 and T 90 of 184 and 206 °C at a space velocity of 15 000 mL/(g h) with 1000 ppm toluene, respectively), stability, and durability (5 vol % water). The excellent activity of LCO-20 might be mainly ascribed to the accelerated activation and circulation of the oxygen species initiated by the surface defects and Co2+/Co3+ redox cycles.

Insights into the role of strontium in catalytic combustion of toluene over La1−xSrxCoO3 perovskite catalysts

“…Compared with the LaCoO 3 treated with HNO 3 for 20 minutes, which is described in the literature, 46 it shows considerable performance in toluene catalytic combustion activity, but the L 0.82 S 0.18 C sample shows a higher reaction rate in terms of reaction rate. Compared with other literature reports, the L 0.82 S 0.18 C sample also showed considerable activity and a better reaction rate.…”

Low temperature magnetic behavior and thermal expansion anomaly of cubic CeTiO3

“…Lanthanum LnBO 3 -based perovskite oxides have demonstrated fascinating performances in ionic conductivity, 1 photoelectricity, 2 catalysis, 3 ferroelectric and magnetism. 4,5 By adjusting the chemical composition appropriately, the crystal structure together with charge and electronic structure can be facilely manipulated, which triggers the lattice distortions of BO 6 -octahedra and engineers the unusual physical properties.…”

Effect of Acid Treatment on the Catalytic Activity and Mechanical Stability of SmMnO3/Cordierite Monolithic Catalysts

“…[30] Besides, Chen et al employed HNO 3 solution to treat LaCoO 3 perovskite oxides and synthesized surface Co-enriched LaCoO 3 perovskite oxides, in which the unique LCO catalysts could enhance the electron transfer and facilitate the activation of oxygen molecules through the interface Co 2 + /Co 3 + redox cycles. [31] Si et al reported a novel γ-MnO 2 -SR obtained by selectively removing La cations from 3DOM LaMnO 3 has mesoporous morphology and γ-MnO 2 -like structure, which shows excellent catalytic performance in toluene oxidation between the γ-MnO 2 -SR and other MnO 2 catalysts (α-, β-, γ-MnO 2 ) prepared by traditional methods. [32] Xu et al successfully developed to obtain a series of 3D meso/macro-porous materials by using acid to etch manganite perovskite (LaMnO 3 ), in which strength and oxidizing properties of the acid used as modifying agent strongly impact textural and redox surface properties of the resulting materials.…”

“…Besides, Chen et al. employed HNO 3 solution to treat LaCoO 3 perovskite oxides and synthesized surface Co‐enriched LaCoO 3 perovskite oxides, in which the unique LCO catalysts could enhance the electron transfer and facilitate the activation of oxygen molecules through the interface Co 2+ /Co 3+ redox cycles [31] . Si et al.…”