Methane catalytic combustion over La–Ce–Mn–O- perovskite prepared using dielectric heating

Abstract

Abstract In the present work we report on the influence of the preparation method on the physicochemical and catalytic properties of La–Ce–Mn–O- catalysts used for methane combustion. Samples were prepared hydrothermally using both conventional (CH) and dielectric heating (MH). Catalysts were characterized by N 2 adsorption–desorption, X-ray powder diffraction (XRD), temperature-programmed reduction by H 2 (H 2 -TPR) and temperature-programmed desorption-mass spectrometry (TPD-MS). An analysis of XRD and TPR data leads us to conclude that microwave irradiation leads to formation of La 1− x Ce x MnO 3 + e CeO 2 ( x + e = 0.2), whereas conventional heating leads to CH-LaMnO 3 + CeO 2 systems. Catalytic combustion of methane without and with 100 ppmv H 2 S was carried out using a GHSV of 8000 h −1 and oxygen-to-methane ratio of 4. Microwave prepared sample was found to be the best both in terms of sulphur tolerance and percent CH 4 conversion. The superior catalytic performance of the catalyst prepared using dielectric heating was attributed to a well dispersed cerium oxide species strongly interacting with the LaMnO 3 host structure.