International Journal of Renewable Energy Development
Vol 15, No 3 (2026): May 2026

Methyl ester production from high free fatty acid content with Ce/Zeolite bifunctional catalyst

Syahidah, Aisyah Sabrina Nurul (Unknown)
Wilujeng, Dinanti Putrisia (Unknown)
Widayat, W. (Unknown)
Hadiyanto, H. (Unknown)
Sulardjaka, S. (Unknown)
Ngadi, Noorzita (Unknown)



Article Info

Publish Date
01 May 2026

Abstract

The production of methyl esters from high free fatty acid (FFA) feedstock remains a critical challenge in biodiesel processing, particularly when using Palm Acid Oil–waste cooking oil (PAO–WCO) with an initial FFA content of 53.21%. Such high FFA content significantly reduces reaction efficiency and necessitates a conventional two-step process involving esterification to lower the FFA level followed by transesterification to convert triglycerides into methyl esters. This multistep approach limits process efficiency and increases operational complexity for high-FFA feedstock. This study investigates the use of a bifunctional Ce/Zeolite catalyst to enable simultaneous esterification and transesterification in a single-step process for high FFA content oil. The zeolite support was synthesized from geothermal waste, and cerium was incorporated via impregnation. The catalyst was characterized using SEM–EDX, X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analyses. The reaction was conducted under various operating conditions, including different temperatures and catalyst loadings. The Ce/Zeolite catalyst exhibited effective bifunctional activity, enhancing the simultaneous conversion of FFAs and triglycerides in high FFA content feedstock. The optimum conditions were a methanol-to-oil molar ratio of 12:1, 4 wt% catalyst loading, and a reaction temperature of 50 °C for 180 min. Under these conditions, FAME concentration of 91.5% was obtained, with FFA conversion of 25.31% (reduction of 13.47% FFAs from initial 53.21%) achieved in a single-step transesterification process. These results demonstrate that Ce/Zeolite is a promising bifunctional catalyst for the efficient processing of high FFA content oil, offering a simplified and more sustainable pathway for industrial biodiesel production.

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Journal Info

Abbrev

ijred

Publisher

Subject

Control & Systems Engineering Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering

Description

The International Journal of Renewable Energy Development - (Int. J. Renew. Energy Dev.; p-ISSN: 2252-4940; e-ISSN:2716-4519) is an open access and peer-reviewed journal co-published by Center of Biomass and Renewable Energy (CBIORE) that aims to promote renewable energy researches and developments, ...