Steam CO_2 Reforming of Methane over La_(1-x)Ce_xNiO_3 Perovskite Catalysts

摘要

La_(1-x)Ce_xNiO_3 catalysts were prepared by modified EDTA-cellulose method. The prepared catalysts were characterized by various techniques such as N_2 physisorption, TPR, XRD, TPH, TEM-EDS and TG analysis. It was observed that the substitution of Ce resulted in easier reduction of the catalyst. The performance and stability of the catalysts for the steam CO_2 reforming of CH_4 were investigated under the reaction conditions of 600 ～ 900 °C, 1 bar and feed molar ratio of CH_4 : H_2O : CO_2 = 1 : 1 : 1. It was considered that the substitution of small amount of Ce in the catalyst could activate CH_4 and CO_2 and it led to higher conversions and CeO_2 suppressed carbon formation. However the substitution of large amount of Ce species led to the methanation of CO_2 as well as water gas shift reaction. It was found that the conversions of CH_4 and CO_2 decreased in the following order : La_(0.9)Ce_(0.1)NiO_3 ＞ LaNiO_3 ＞ La_(0.5)Ce_(0.5)NiO_3.