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Browsing Research Repository by Author "Ao, Supongsenla"

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    Design and Synthesis of Engineered Biobased Catalysts for Biodiesel and its Fuel Additive Production: Study on Kinetics, Thermodynamics and Life Cycle Assessment
    (Department of Chemistry, NITS, 2026-02-12) Ao, Supongsenla
    This thesis focuses on the design, synthesis, and characterization of bio-based heterogeneous catalysts for applications in biofuels and their additives, with particular emphasis on materials derived from bio-waste. Utilizing these waste-derived catalysts not only promotes sustainability but also offers a low-cost and renewable alternative to conventional materials. To improve process performance and capture the interaction between key operational variables, response surface methodology is employed. Building on this optimization, the environmental viability of the overall approach is assessed using life cycle assessment, which provides quantitative insights into the ecological impact of the manufacturing processes and guides informed, sustainability-oriented decision-making This thesis has been organized into 8 chapters. Chapter 1 introduces the research problem and study area, beginning with a historical overview of biofuels and their additives, followed by a timeline of developments in heterogeneous catalysis. This background establishes the foundation for discussing the motivation and scope of the study. Chapter 2 provides a detailed systematic literature review on catalysis for trans/esterification and acetalization of glycerol for this study and formulates the objectives of this study. In Chapter 3, we present the synthesis of a novel nanocomposite, calcium oxide-magnetite (CaO-Fe₃O₄ NCs), derived from waste inorganic biomass (snail shell) using a wet impregnation method. This process involves sequential calcination, hydration, and dehydration steps to address the first research gap of this study minimizing catalyst active site leaching and enhancing recyclability. In Chapter 4, we divided the content into three sections: Chapter 4a, Chapter 4b, and Chapter 4c. In Chapter 4a, we produce a porous biochar catalyst through simultaneous activation and graphitization. This catalyst was then used to optimize the transesterification of JCO using the response surface methodology- central composite design method (RSM-CCD) method. A life cycle assessment was also performed to evaluate the environmental impact of biodiesel production from JCO. In Chapter 4b, a similar catalyst preparation approach was explored using lemon peel as the biomass raw material. This section specifically investigated the effect of porous activator ZnCl2 on the biochar. Likewise, Chapter 4c examined the impact of the porosity activator, but using paper waste as the biomass substrate. Chapter 5 explores the tendency of basic catalysts to induce saponification in environment that are high in free fatty acids, where a two-phase process involving both acid and basic catalysts is commonly needed. To address this challenge, bifunctional catalysts have been developed to facilitate single-step reactions, reducing the need for complex extraction and separation processes. Moving on from biodiesel production, in Chapter 6, the production of solketal, a potential-fuel additive to valorize the large waste stream generated from biodiesel industry was investigated by acetalization using a sulfonic acid-functionalized aromatic carbonaceous material (SAFACAM) as a catalyst under microwave irradiation. Here, catalyst recovery was probed over six cycles, with a modest loss in activity. Chapter 7, outlines the final objectives of our thesis, aiming to synthesize a low-cost biochar (lotus leaf) derived carbon nanodots catalyst through hydrothermal carbonization to form solketal. Employing the RSM-CCD methodology, the experimental matrix was executed, and subsequent data were scrutinized through multiple regressions to model a quadratic equation. Under specific reaction parameters, maximum solketal yield of 95.7 % was attained through the ultrasonication method. Furthermore, life cycle cost analysis (LCCA) for solketal production was studied here, which determined the overall cost of solketal production indicating high commercial applicability. Finally, Chapter 8 summarizes and concludes the findings of the study. In conclusion, this thesis demonstrates the synthetic value of several functionalized biomass-derived catalysts, addressing key limitations that exists in the current biofuel industry. The catalytic pathways and environmental impacts have been optimized for both efficiency and environmental sustainability. These catalysts hold significant potential for future research and could be explored for various organic synthesis processes in the near future.