Abstract: Catalytic reforming of natural gas is a commercial process to produce syngas, which is the main source for the production of ammonia, methanol, hydrogen, and many other important products. This method produces also large amounts of CO₂ as by-product. Chemical-looping reforming (CLR) is a novel technology that can be used for syngas production by partial oxidation and steam reforming of hydrocarbon fuels. One key issue with the CLR concept that is being widely studied is the oxidation and reduction behavior of potential oxygen-carrier materials. Four perovskite-based nano-composite oxides were prepared by the sol-gel method and characterized by X-ray diffraction, N₂ adsorption-desorption, scanning electron microscopy (SEM), and CH₄ temperature-programmed surface reaction. The catalytic performance of the prepared samples for CLR of CH₄ to syngas was investigated. The results showed that the LaMO₃ (B = Cr, Mn, Fe, and Co) oxides possess perovskite-type nano-composite structure. The oxidizing ability of these four perovskite oxides follows the order of LaCoO₃ > LaMnO₃ > LaFeO₃ > LaCrO₃. Among them, LaFeO₃ oxide has higher activity for CLR of CH₄ to syngas. The CH₄ conversion and CO selectivity are 89.6% and 98.9%, respectively. Especially, the sequential redox reaction revealed that the LaFeO₃ oxide exhibits high stability with CH₄ conversion of 60%~70% and CO selectivity of ~98% after 10 redox cycles. The SEM analysis revealed that the structure of the LaFeO₃ oxide was not dramatically changed before and after 10 cyclic reactions.

Key words: methane, chemical-looping reforming, perovskite, B-site cation, oxygen carrier, syngas