Conventional hydrothermal process versus microwave-assisted hydrothermal synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) perovskites used in methane combustion |
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Authors: | Simon Ifrah Akim Kaddouri Patrick Gelin Didier Leonard |
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Institution: | aIRCELYON, Institut de recherches sur la catalyse et l'environnement de Lyon, UMR 5256, CNRS-Université Claude Bernard Lyon1, 2 Av. A. Einstein, Villeurbanne F-69626, France;bCNRS, UMR 5256, Villeurbanne F69626, France;cLaboratoire des sciences analytiques UMR 5180, CNRS-Université Claude Bernard Lyon1, Villeurbanne F-69626, France |
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Abstract: | A study on the synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure (T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h).Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La0.8Ag0.2MnO3+δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts. |
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Keywords: | Perovskites Hydrothermal synthesis Microwaves Methane combustion Sulphur poisoning Oxygen mobilityMot-clé s: Pé rovskites Synthè se hydrothermale Micro-ondes Combustion du mé thane Empoisonnement par le soufre Mobilité de l'oxygè ne |
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