Kalsinasyon Sıcaklığının Modifiye Edilmiş Pechini Yöntemi ile Hazırlanan Perovskit Özelliklerine Etkisi

Abstract

Perovskite type oxides which have the general formula as ABO 3 including both rare earth elements and 3d transition metals is gaining interest according to be utilized as such strategic materials because of their excellent catalytic, magnetic, electrical and optical properties. Along with perovskitic materials, lanthanum nickel oxide (LaNiO 3 -LNO) shows potential as a consequence of its electronic and catalytic properties in not only reactions like reforming, redox reactions but also in storage and conversion of energy or synthesis an electrode material. LNOs are widely prepared by methods like sol-gel, co-precipitation, solid state and Pechini. Among these methods, the Pechini method uses the common metal salts consisting of nitrates, acetates, chlorides, etc. as precursors and citric acid (CA) as a chelating agent of metal ions and ethylene glycol (EG) as a cross-linking agent to form a polymeric resin on molecular level and declines segregation of metal ions and ensures compositional homogeneity. This process can defeat most of the difficulties and disadvantages that frequently occur in the alkoxides related to sol−gel method. The present work attempts to scan the effect of calcination temperature on the physical properties of LaNiO 3 catalysts prepared by modified Pechini method without ethylene glycol. In order to lay out the physical properties, X-ray diffraction (XRD), scanning energy micoscopy (SEM), and N 2 adsorption/desorption techniques were used. The change with the temperature in the structure caused a decrease in surface area, pore volume and increase in pore size. XRD studies revealed that calcination of LNO at 700°C favored the formation of an almost homogeneous LaNiO 3 perovskite phase rather than calcination at 500°C. The study underlined that the preparation of the LNO by the modified Pechini method can be applied successfully with the temperature above 700°C without EG as a cross-linking agent.