Green synthesis of modified ceria nanoparticles and their catalytic activity studies

Abstract

Catalysis is a phenomenon where a reaction is taken through an alternative pathway involving lesser energy. Thus, it has an energy saving dimension implicit in its definition. This thesis involves the study of catalysts, synthesized by the solution combustion method. The fuel required for the newlinecombustion is aqueous extract obtained from the leaves of selected plants which gives added credence to the ecofriendly aspirations that dominated our work. A series of ceria based nano sized catalyst materials, pure and modified using rare earth metal oxides, transition metal oxides and a non-metallic substance have been synthesized by the above method. The catalysts have then been newlinecharacterized for their composition, crystallinity, morphology, surface properties, thermal stability etc. The prepared catalysts were subsequently evaluated for their catalytic and photocatalytic efficacy. The photocatalytic potential of the catalysts was evaluated on the degradation studies of two dyes Malachite Green (MG) and Congo Red (CR) under visible light and one antibiotic drug ciprofloxacin (CIP) under UV light. The catalysts were found to show good photocatalytic efficiency newlineon all the three substances mentioned above. The catalytic efficiency was evaluated on two chemical reactions. One, the reduction of 4-nitrophenol to 4-aminophenol and the other, the synthesis of compounds of Biginelli reaction. To achieve maximum reduction the experimental conditions for the catalyst were newlineoptimized. Biginelli reaction involves the condensation of ethyl acetoacetate, newlinebenzaldehyde and urea in presence of modified ceria catalysts to form dihydropyrimidines. The reaction was performed with different catalysts and the one which gave the best yield was selected for further optimization of other reaction conditions. Employing the optimized conditions, a set of different newlinedihydropyrimidinone derivatives were synthesized by varying the precursor newlinealdehydes and ketones. Reusability studies for the catalysts were conducted for all the reactions mentioned above.