Production of High-Efficiency Alternative Biodiesel from Transesterification of Waste Cooking Oil Using an In-house Made Y-Type Zeolite Catalyst

Abstract

Y-zeolite catalyst, with a Si/Al ratio of 2.23 and a high surface area of 703.34 m2/gcat, was prepared with three different particle sizes: 75, 600, and 1000 μm, from commercial Ludox AS-40 colloidal silica 40 wt.% suspension in water using the hydrothermal method. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analyses were all utilized to analyze the properties of the synthesized Y-zeolite catalyst. Waste cooking oil (WCO) was transesterified to biodiesel in a batch reactor under different temperatures (e.g., 40, 50, and 60 °C) for 3 hours, and the activity of the catalyst was evaluated before and after being loaded with potassium oxide (K2O) molecules using the impregnation method. It is observed that the biodiesel conversion and yield, in the presence of a non-KOH-loaded catalyst, rose with increasing temperature and/or reaction time. However, increasing the reaction time beyond 2 hours in the presence of the catalyst loaded with 10% KOH decreased biodiesel conversion and yield. It has also been found that using catalysts with smaller particle sizes (e.g.,75 μm) is more favorable for enhancing the conversion of the catalytic process due to the acceleration of the reaction rate. A maximum biodiesel yield and conversion of 84.44% and 80%, respectively, were obtained. Using Gas Chromatography-Mass Spectrometry (GCMS), the composition and physical characteristics of the produced biodiesel were compared with those of standard fuels and the comparison results were particularly satisfactory. The spent Y catalyst loaded with KOH was recovered, reactivated, and reused in subsequent reactions. It exhibited outstanding catalytic activity, which is a testament to its cost advantage since it could significantly reduce the need for large quantities of costly homogeneous catalysts that are difficult to separate from the reaction products.