ItemPhD

Preparation characterization and applications of mixed oxides ceria-samaria supported on rice husk ash as catalysts for organic synthesis

Title
Preparation characterization and applications of mixed oxides ceria-samaria supported on rice husk ash as catalysts for organic synthesis
Creator
Selva Priya, A.
Contributor
K R, Sunaja Devi.
Description
Catalysis is a well-established scientific discipline, dealing with fundamental principles involved in the preparation, properties, applications and mechanisms of catalytic reactions of various catalysts. The preparation of silica from agricultural waste rice husk is an economical and environmentally benign process. Mixed oxides of ceria and samaria are a multifunctional catalytic system that has attracted wide-range of research in different fields. These mixed oxide catalysts are generally used for redox reactions and acid-base reactions in organic synthesis. The catalytic activity of these materials can be enhanced by using silica as a support system. To achieve the best structural and morphological features, different synthetic protocols were tried out while incorporating CeO2 and Sm2O3 on SiO2 to maximize the catalytic efficacy. In the present study, bimetallic oxides of ceria and samaria supported on silica catalysts were prepared by ultra sonicator, rota vapour method, wet impregnation and incipient wet impregnation methods. Further modification of ceria-samaria-silica catalysts using MoO3, La2O3 and mixed forms of MoO3 and La2O3 led to the formation of tri or tetra metallic mixed oxides on silica system. A detailed physico chemical characterization of the prepared catalysts using different spectroscopic and non-spectroscopic methods was carried out to understand the nature, stability and the functional groups present in the system. The heterogeneous catalytic route for organic synthesis is of major interest as it is sustainable and eco-friendlier. Utilizing biowaste like rice husk and its modified forms to synthesize useful and industrially significant organic compounds has been attempted with success in the present work. Thus, the prepared catalysts were subsequently evaluated for their catalytic activity towards oxidation, esterification, transesterification and Friedel Crafts' benzylation reactions. To achieve maximum yield and good selectivity, the different reaction parameters were optimized for all the reactions that were studied. Oxidation of cyclohexanone with benzyl alcohol to caprolactone and benzaldehyde has been studied after optimizing the reaction parameters. Recycle and leaching studies were conducted to understand the stability and reusability of the catalytic system for the above-mentioned reactions. These catalysts were also found effective in the synthesis of caprolactone, which is an intermediate in the synthesis of biodegrading polymers. Selective oxidation of benzyl alcohol to benzaldehyde too has been achieved using these catalysts. Surface area and acidity have played major roles in these reactions. Finally, dibenzyl toluene was synthesized by benzylation of toluene using benzyl chloride. In all the studies, plausible mechanisms involving the catalyst have also been suggested. Thus, a comprehensive study of rice husk silica-supported ceria and samaria systems and the multi metal oxide silica systems has been conducted and it has proved to be an efficient, recoverable, stable and eco-friendly catalyst combined with simple workup for industrially important organic syntheses.
Source
Author's Submission
Date
2020-01-01
Publisher
Christ(Deemed to be University)
Subject
Chemistry
Rights
Open Access
Relation
61000136
Format
PDF
Language
English
Type
PhD

Collection

PHD

Citation

Selva Priya, A., “Preparation characterization and applications of mixed oxides ceria-samaria supported on rice husk ash as catalysts for organic synthesis,” CHRIST (Deemed To Be University) Institutional Repository, accessed February 23, 2025, https://archives.christuniversity.in/items/show/12076.

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