Assessment of Catalyst Performance in Biodiesel Production from Waste Cooking Oil

Thesis Abstract

The escalating demand for sustainable energy sources has heightened interest in biodiesel production from waste cooking oil, which offers an environmentally friendly and cost-effective alternative to conventional fossil fuels. However, the efficiency and economic viability of biodiesel synthesis are critically dependent on the performance of catalysts employed in transesterification processes. Despite extensive research, there remains a lack of comprehensive empirical data comparing catalyst types, preparation conditions, and operational parameters influencing biodiesel yields and quality, thus limiting commercialization prospects. This study aims to evaluate the performance of heterogeneous catalysts in biodiesel production from waste cooking oil, with specific objectives to determine optimal catalyst formulations, assess reaction kinetics, and analyze catalyst reusability and stability under varying operational conditions. The research adopts an experimental research design, combining quantitative analysis with factorial experimental methods to systematically investigate catalyst efficacy. The population encompasses waste cooking oil samples sourced from 15 local food service establishments within the urban area, pooled to create a representative feedstock batch. A total sample size of 120 catalytic trials is devised based on a 3x4x5 factorial design, involving three catalyst types—calcium oxide, potassium hydroxide, and a bio-based catalyst derived from calcined eggshells—each tested across four temperature levels (60°C, 70°C, 80°C, 90°C) and five methanol-to-oil molar ratios (61, 91, 121, 151, 181). Data collection instruments include gas chromatography-mass spectrometry (GC-MS) for biodiesel composition analysis, Fourier-transform infrared spectroscopy (FTIR) for functional group identification, and titrimetric methods for measuring free fatty acid (FFA) content pre- and post-reaction. The validity and reliability of the analytical instruments are confirmed through calibration with standard samples, and experimental controls are implemented to mitigate variability. Data analysis involves descriptive statistics to characterize biodiesel yields and properties, followed by analysis of variance (ANOVA) to compare catalyst performance across different operational parameters. Kinetic modeling employs first-order reaction assumptions, with regression analysis establishing relationships between reaction variables and biodiesel conversion rates. Catalyst reusability is evaluated through repeated reaction cycles, and durability assessed via structural and compositional analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Expected findings anticipate that calcium oxide will demonstrate higher catalytic activity at elevated temperatures and optimal methanol ratios, with significant improvement in biodiesel yield and quality relative to other catalysts. The study expects to establish kinetic rate constants and activation energy values, providing insight into the catalytic mechanisms involved. Reusability assessments are projected to reveal durability potential, with variations in catalyst deactivation linked to sintering and leaching phenomena identified through SEM and EDX analyses. These results will contribute empirical evidence to optimize catalyst selection and operational parameters, underpinning scalable and sustainable biodiesel production processes. The findings of this research will significantly advance knowledge regarding catalyst performance in biodiesel synthesis from waste cooking oil, informing industrial practices and policy frameworks aimed at sustainable energy development. By elucidating the relationships between catalyst type, reaction conditions, and biodiesel quality, the study offers practical guidelines for enhancing process efficiency and cost-effectiveness. The primary conclusion underscores that calcium oxide exhibits superior catalytic performance under specified conditions, with high reusability prospects, thus presenting a viable option for commercial biodiesel production. Recommendations include further investigation into catalyst regeneration techniques, scale-up studies, and lifecycle assessments to promote sustainable deployment. This research lays the groundwork for subsequent innovations in catalyst design and process optimization for biofuel manufacturing from heterogeneous feedstocks.