Abstract
A large amount of CO as hazardous emission in the iron ore sintering process has caused severe harm to the environment and human health. To control the emission of CO more effectively, the preparation of highly efficient catalysts has attracted much attention. In this study, the La1-xSrxMnO3 (0 ≤ x < 1) perovskite catalysts with different Sr2+ contents were prepared by the one-step flame synthesis method to treat CO pollutants in the iron and steel industry. The influence of Sr2+ doping on the structure and activity of catalytic were characterized and analyzed. La1-xSrxMnO3 perovskite catalysts exhibit good perovskite phases and loose spherical structures. The specific surface areas are between 4.1 and 12.0 m2 g−1. Combined with the results of H2-TPR and O2-TPD, the improvement of catalytic activity of La1-xSrxMnO3 perovskite can be attributed to the high concentration of active centers and oxygen vacancies. Significantly, the La0.4Sr0.6MnO3 catalyst presented the best reducibility and high content of absorbed active oxygen species, leading to a superior CO oxidation catalytic activity and reaches 50% CO conversion at 134.9°C and 90% at 163.2°C, respectively. The effects of water vapor and CO2 on the oxidation activity of La1-xSrxMnO3 perovskite was investigated. The flame-produced catalysts exhibit favorable catalytic stability and antisintering ability, achieving 100% CO conversion after fifth consecutive oxidation cycles.
Highlights
Carbon monoxide is a typical air pollutant, which is usually produced by the incomplete combustion of carbon-containing materials and hydrocarbons, such as coal, oil, and natural gas [1]
Kim et al [16] synthesized La0.2Sr0.8Co1-xFexO3-δ and Ba0.5Sr0.5Co1xFexO3-δ nanoparticles perovskites by the flame synthesis, and the results showed that oxygen evolution activity was improved
The atomic ratios of catalysts are presented in Table 3. e atomic ratio of La and Mn were similar for LaMnO3, 50.44% and 49.56%, respectively. e theoretical deviation (La + Sr)/Mn in the perovskite samples prepared by the flame synthesis method is in good accordance with the nominal ones
Summary
Carbon monoxide is a typical air pollutant, which is usually produced by the incomplete combustion of carbon-containing materials and hydrocarbons, such as coal, oil, and natural gas [1]. Noble metal catalysts (Ru, Pt, and Au) exhibit high catalytic activity and have been widely researched in CO oxidation. They are susceptible to sintering, expensive, and the activity decreases with the increased reaction time [6, 7]. Abe and Laine [15] prepared perovskite-type nanoparticles La2TiO7 by the flame spray pyrolysis method, and the catalysis had superior photocatalytic activity. Erefore, it is necessary to develop an alternative method for the one-step synthesis of perovskite catalysts for CO oxidation with desired physical and chemical properties. Is study synthesized a series of La1-xSrxMnO3 (0 ≤ x < 1) perovskites catalysts with different Sr2+ contents by a one-step flame synthesis method for CO oxidation. Is study synthesized a series of La1-xSrxMnO3 (0 ≤ x < 1) perovskites catalysts with different Sr2+ contents by a one-step flame synthesis method for CO oxidation. e performance evaluation and physicochemical properties of flame-produced nanoparticles were comprehensively analyzed. e effects of Sr-doping on the properties of catalysts were revealed
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