SrCaAl mixed oxides derived from LDH as a novel and efficient base catalyst for Knoevenagel condensation: multivariate optimization study

Abstract

Abstract The Knoevenagel condensation reaction is one of the most important reactions in industry for the synthesis of organic materials, medicinal, and biological compounds. In this work, we have proposed an original and efficient solid-based catalytic system for the Knoevenagel condensation reaction. For the first time, a mixed oxide catalyst derived from HT-like Sr0.5Ca2.5Al was synthesized and calcined at 850 ºC, and characterized by various techniques. This catalyst was also compared with the usual Ca3Al sample in terms of structural characteristics and catalytic activity. The nanocatalyst acted as a solid base in the Knoevenagel reaction, facilitating the reaction between three active methylene compounds and benzaldehyde. The findings revealed that the Sr0.5Ca2.5Al sample is highly active in this reaction compared to the Ca3Al sample due to its strongly basic sites. The effects of reaction time, amount of catalyst, and reaction temperature on benzaldehyde conversion (%) and product selectivity (%) were assessed in this study using the Box-Benken design.The appropriateness of the quadratic regression model was evaluated through ANOVA method. The experimental results demonstrate the validity and appropriateness of the model. In addition, under optimal conditions, the conversion percentage of benzaldehyde and product selectivity reached 97% and 84% respectively.