Bifunctional Heterogeneous Catalyst for Biodiesel Production from Waste Vegetable Oil

Samya Elias,Oluwaseun Oyekola,Vincent Okudoh,Ademola M Rabiu,Benjamin I Okeleye

doi:10.3390/app10093153

Samya Elias, Oluwaseun Oyekola + Show 3 more

Open Access

https://doi.org/10.3390/app10093153

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Journal: Applied sciences	Publication Date: May 1, 2020
Citations: 35	License type: CC BY 4.0

Affiliation: Cape Peninsula University of Technology

Abstract

Bifunctional solid catalysts facilitate the esterification of free fatty acids (FFA) into alkyl esters alongside the transesterification reaction, which allows for the use of waste vegetable oils with high water and FFA contents for biodiesel production. This makes the process economically viable and greener, as the waste fats and oils are readily available. The concurrent esterification and transesterification of waste palm oil (WPO) and waste sunflower oil (WSO) with methanol was investigated in the presence of calcium oxide on alumina catalyst in a conventional batch process. The catalyst characterization showed the existence of calcium oxide aluminates (calcined at 750 °C), which exhibited crystalline phases with porous/spongy-like particles. The high concentration of CaO in CaO/Al2O3 was a favorable support material in the heterogeneously-catalyzed transesterification reactions. The optimum catalyst parameters for the production of fatty acid methyl esters (FAMEs) were observed at 65 °C for 4 h with a methanol-to-oil ratio of 9:1, 60% (waste palm oil, or WPO) and 80% (waste sunflower oil, or WSO), CaO/Al2O3 (% wt/wt) catalyst ratio as well as 4% CaO/Al2O3 concentration (% wt.) for WSO and WPO. The simultaneous esterification/transesterification reactions at optimum conditions on WPO and WSO led to high yield of FAMEs of 89, 61 and 55% for WPO and 54, 75 and 98% for WSO at catalyst ratios (wt %) of 60, 70 and 80% respectively. The use of bifunctional heterogeneous catalyst (CaO/Al2O3) with waste vegetable oil can result in high performance and the upscaling of biodiesel production.

Highlights

The ever-growing rate of energy production and consumption with its attendant release of greenhouse gases cause ever-increasing adverse environmental effects, which in turn affect the well-being of humans [1]
The simultaneous esterification/transesterification reactions at optimum conditions on waste palm oil (WPO) and waste sunflower oil (WSO) led to high yield of fatty acid methyl esters (FAMEs) of 89, 61 and 55% for WPO and
The use of bifunctional heterogeneous catalyst (CaO/Al2 O3 ) with waste vegetable oil can result in high performance and the upscaling of biodiesel production

Summary

Introduction

The ever-growing rate of energy production and consumption with its attendant release of greenhouse gases cause ever-increasing adverse environmental effects, which in turn affect the well-being of humans [1]. The majority of the energy consumed globally originates from petroleum, charcoal, and natural gas. These sources are limited and could possibly be depleted in the centuries [2,3]. The decline in global fossil energy resources will result in an increase in the crude oil prices and make renewable and sustainable energy sources more attractive. There is a necessity to find clean and renewable energy supplies, which is environmentally benign, to substitute current fossil energy sources. Biodiesel produced from the transesterification of triglycerides molecules in vegetable oils, animal fats, and waste oils such as yellow grease and soybean soapstock) is a promising alternative energy source because of its lower emissions of particulate matter and greenhouse gases [4]

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