Study On The Catalytic Performance Of La-Ni-O Catalysts For Partial Oxidation Of Methane

Partial oxidation of methane (POM) to syngas has attracted both academic and industrial interest. Compared with steam reforming, POM is more energy efficient and can be carried out with a much lower investment of capital. POM produces syngas with a H₂/CO ratio of ca. 2, which is suitable for use in the production of methanol and Fisher-Tropsch synthesis. Nickel-based catalysts are promising for its industrialization because of their high activity and relatively low cost. However, their application is limited due to their easy deactivation under reaction condition. Thus, it is important to develop the useful POM catalysts with ideal stability.In this work, the effects of different preparation condition on the structure and POM reactivity of NiO/La₂O₃, LaNiO₃ and La₂NiO₄ were examined. The structure and POM reactivity of LaNiO₃ and La₂NiO₄ were compared systemtically.NiO/La₂O₃ was prepared by wet impregnation method. The research on NiO/La₂O₃ showed that the provskite structure of LaNiO₃ can be formed after calcinations at high temperature, the NiO/La₂O₃ contained 20～30wt.% nickel exhibited good activity for partial oxidation of methane, La₂O₂CO₃ formed during reaction is probably species, which may favor removal of carbon deposition existed in MxC.LaNiO₃ and La₂NiO₄ were successfully prepared by a sol-gel method and used in partial oxidation of methane. The results showed that the amount of citric acid and calcination temperature have significant influence on the characteristics of the catalysts and their catalytic activity. The catalyst reduced in H2 at 500℃showed better POM performance.Ni0 is active site of the POM reaction, perovskite-like oxide La₂NiO₄ presents smaller nickel particle NiO after reduction treatment. Consequently the catalytic activity is higher than perovskite oxide LaNiO₃.The carbon deposition had formed on catalysts LaNiO₃ and La₂NiO₄ in POM reaction. Most of the carbon deposited on La₂NiO₄ was MxC, which can be removed by La₂O₂CO₃, while one on LaNiO₃ was graphite which is low active. So the stability of perovskite-like oxide La₂NiO₄ is better than perovskite oxide LaNiO₃.