Synthesis Of Electrospun LaCoO₃ Fibers At Low Temperature And Their Catalytic Properties Of Benzene Oxidation

The massive emission of volatile organic compounds ?VOCs? has caused serious environmental pollution, which threatens the health of people. Catalytic oxidation of VOCs over perovskite-type oxide is an attractive, viable technology because of its lower cost and higher efficiency. However, the potential applications of these materials are greatly limited by their small surface areas and high-temperature thermal treatment to obtain a pure crystalline perovskite.In this study, electrospinning technology was adopted to synthesis perovskite LaCoO₃ at relatively low temperature calcination ?500??. The obtained LaCoO₃ bwere characterized by means of XRD, SEM, TEM, N₂ adsorption-desorption isotherms, H2-TPR and XPS, respectively. Their catalytic performance were evaluated by benzene oxidation.Firstly, the influence of solvents and complex reagents on the morphologies and catalytic performance of LaCoO₃ fibers was investigated. The results show that DMF not only serves as a solvent but also as a compalexant to facilitate the crystallization of perovskite LaCoO₃at a low temperature. Interestingly, DMF can improve the redox property of the surface of perovskites, resulting in an enhancement of catalytic activities of LaCoO₃ fibers. However, the addition of complex reagents ?citric acid or glucose? suppresses the capability of DMF, which contradicts with the observed phenomenon in water solution during electrospinning.Secondly, LaCoO₃ fibers were etched by NaOH solution. The results show that fluff-like La?OH?₃ is observed on the surface of LaCoO₃ fibers after a NaOH leaching process, revealing that LaCoO₃@La?OH?₃ fibers were successfully synthesized by in-situ electrospinning-alkali treating progress. As expected, the LaCoO₃ fibers after NaOH etching has larger surface areas and better catalytic performance for benzene oxidation. In addition, LaCoO₃ with an etching treatment of 3 h achieves the optimum catalytic activities, while a longer etching time has adverse effect.Finally, electrospun LaCoO₃/SBA-15 hybrid catalyst was synthesized by mixing SBA-15 into the precursor solution. After removal of SBA-15 by NaOH solution treatment, the surface area of perovskite LaCoO₃ composed of nanorods and nanoparticles were increased to 44 m²/g from 23 m²/g ?LaCoO₃ fibers obtained from common electrospinning?, which significantly enhances the catalytic performance of LaCoO₃.