The preparation, characterization, and catalytic performance of porous fibrous LaFeO 3 perovskite made from a sunflower
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RESEARCH ARTICLE
The preparation, characterization, and catalytic performance of porous fibrous LaFeO3 perovskite made from a sunflower seed shell template Zhifei Wu1, Li Wang1, Yixiao Hu2, Hui Han1, Xing Li1, Ying Wang (✉)1 1 School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, China 2 College of Science & Technology, Ningbo University, Cixi 315000, China
© Higher Education Press 2020
Abstract LaFeO3 perovskite with a porous fibrous structure was successfully synthesized using a sunflower seed shell as a template. To investigate the effects of this template, a sample was prepared without a template via the same procedure. Through various characterization techniques, such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy, oxygen temperature programed desorption, and hydrogen temperature programed reduction, the physiochemical properties of the samples were investigated. The results showed that the sample made with a template had a larger surface area and a larger amount of adsorbed oxygen, which further illustrated that the sunflower seed shell template had a significant impact on the physiochemical properties of the samples. Furthermore, we explored the catalytic activity for nitric oxide (NO) oxidation, and studied the factors affecting it, which highlighted its potential application in automobile exhausts. Keywords NO oxidation, porous fibrous LaFeO3, sunflower seed shell
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Introduction
With the rapid development of industry, the pollution of vehicle motor emissions has become a compelling issue that has adverse effects on public health and the ecosystem [1]. Nitrogen oxides (NOx), produced as a result of combusting fuel at excessive temperatures, are major ingredients in automobile exhaust gases and are composed Received September 21, 2019; accepted January 15, 2020 E-mail: [email protected]
of nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O) [2]. Selective catalytic reduction (SCR) and NOx storage and reduction (NSR) are well-developed techniques that convert NOx into nitrogen. It has been found that NO accounts for approximately 90% of the total NOx emissions from automotive exhausts [3]. Since NO2 is more efficiently reduced into nitrogen in SCR or adsorbed as nitrates in NSR, the oxidation of NO into NO2 is critical in these two approaches [4]. Perovskite oxides have been reported as effective catalysts in NO oxidation due to their low cost and high activities [5]. In perovskite oxides (general formula ABO3), rare earth or alkaline earth elements (such as La, K, and Rb) at the A site predominantly play a role in stabilizing the structure, while transition metal elements (Mn, Co, Fe, etc.) at the B site determine catalytic activity [6]. As a member of the perovskite family, LaFeO3 has attracted special attention regarding the catalytic oxidation of harmful gases, such as NO [7], CO and soot [8]. The high stability of LaFeO3 is advantageous for it
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