Síntese de Nd2Zr2O7 pelo método de co-precipitação em meio aquoso com amônia e aplicação na catálise de reações de esterificação

Abstract

According to the literature, materials with a pyrochlore structure have garnered interest due to various applications. Neodymium zirconate (Nd2Zr2O7) stands out among pyrochlores owing to its low thermal conductivity and high thermal expansion coefficient, finding applications in transparent ceramics, electrical conductors, and catalysis. The methodology was based on previous works, employing a 24 factorial design to vary 4 factors at 2 levels, resulting in 16 combinations. Equimolar aqueous solutions containing Nd3+ and Zr4+ ions were precipitated with ammonium hydroxide and subsequently calcined. Concentration, solution temperature, and pre-calcination thermal treatment time were analyzed. The results indicated that higher concentration favored pyrochlore phase formation, emerging as the most influential variable. Precipitation temperature also had a positive effect, while thermal treatment time influenced pyrochlore phase formation, particularly when combined with the amorphous phase. Microwave irradiation showed minor significance, primarily for shorter thermal times. Catalytic activity was not observed for this material in the esterification reaction of oleic acid with ethanol. The research underscores the importance of experimental details in Nd2Zr2O7 synthesis. In conclusion, the study contributes not only to enriching the scientific literature but also to guiding future researchers in pursuit of consistent and reproducible Nd2Zr2O7 syntheses, offering prospects for deeper analyses of these parameter effects.