Synthesis and Characterization of LaNiO3, LaNi(1-x)Fe xO3 andLaNi(1-x)Co xO3 Perovskite Oxides for Catalysis Application

Sania Maria de Lima,José Mansur Assaf

doi:10.1590/s1516-14392002000300018

Sania Maria de Lima, José Mansur Assaf

Open Access

https://doi.org/10.1590/s1516-14392002000300018

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Journal: Materials Research	Publication Date: Sep 1, 2002
Citations: 37	License type: cc-by

Affiliation: Universidade Federal de São Carlos

Abstract

Mixed metal oxides with perovskite-type structure show a great potential to be used in catalysis, electrocatalysis and electronic ceramics. Perovskites oxides catalysts with the composition LaNiO3, LaNi(1-x)FexO3 and LaNi(1-x)CoxO3 (x = 0.4 and 0.7) have been synthesized by the precipitation method to be used in the methane reforming to produce hydrogen and synthesis gas. The compounds were characterized by X-ray diffraction, thermogravimetric and differential thermal analysis, inductively coupled plasma atomic emission spectroscopy, surface area measurements, energy dispersive X-ray spectrometry coupled to scanning electron microscopy and temperature programmed reduction. The results showed that a suitable combination of the preparation method with calcination variables (time and temperature) could result in oxides with the desired structure and with important properties at the application point of view in heterogeneous catalysis.

Highlights

The methane steam and CO2 reforming are endothermic processes for the manufacture of syngas and hydrogen with molar ratio H2/CO between 1 and 31
The X-ray powder diffraction (XRD) diagrams of the oxides prepared according to method 1 showed the formation of other compounds such as NiO and La2O3 besides the perovskite structure, whereas in method 2 the perovskite structure was the only phase observed (Fig. 1)
Synthesis and Characterization of LaNiO, LaNi Fe O and LaNi Co O Perovskite Oxides for Catalysis Application 331 (1-x) x 3 (1-x) x 3 tion, when the pH reached higher values. As this precipitation was performed slow and selectively, it resulted in larger solid particles of homogeneous composition, preventing the subsequent reaction in the solid state for formation of the perovskite structure

Summary

Introduction

The methane steam and CO2 reforming are endothermic processes for the manufacture of syngas and hydrogen with molar ratio H2/CO between 1 and 31. The perovskite lattice can accommodate multiple cationic substitutions with only small changes and in consequence, several properties of the solid, such as sintering and catalytic performance can be modified Those oxides are represented by the general formula ABO3 in which A ions can be rare earth, alkaline earth and alkali that fit into dodecahedral site of the framework, and the B ions can be 3d, 4d and 5d transitional metal ions which occupy the octahedral sites[11]. Aiming at the stabilization of perovskite structure under reductive atmosphere, this work has studied the effect of the preparation variables of LaNiO3, LaNi(1-x)FexO3 and LaNi(1-x)CoxO3 (x = 0.4 and 0.7) perovskite-type oxides for potential applications in the methane reforming reactions. Lanthanum is a rare earth that stabilizes the structure and prevents coke formation, nickel is very active in the methane reforming reactions and the metals Fe and Co present ionic radius close to that of Ni

Experimental

Results and discussion

Conclusion