One-Step Synthesis of CaO-ZnO Efficient Catalyst for Biodiesel Production

Javier Toledo Arana,Juan José Torres,Diego F Acevedo,Cecilia L Pagliero,Nelio A Ochoa,Cristian O Illanes

doi:10.1155/2019/1806017

Abstract

Biodiesel is the best candidate for fuel oil replacement, and to obtain it, heterogeneous catalysts offer large advantages: they can be separated from the product and reused. This work reviews a novel one-step synthesis of CaO-ZnO catalytic particles suitable for biodiesel production. The catalyst is synthesized using an original simple method that involves mixing of ZnO with CaCO3 and subsequent calcination. The CaO-ZnO microparticles obtained present an average size of 2 μm. This material shows the characteristic crystallographic cubic structure of CaO and the hexagonal phase of ZnO. The temperature-programmed reduction experiment evidences an interaction between CaO and ZnO. Moreover, the infrared spectroscopy shows typical bands of these compounds. The catalyst shows high biodiesel yield, up to 73% in the first cycle and 64% in the second one. In this work, the synthesis of an efficient CaO-ZnO catalyst with a huge potential is revealed, which could be an economic alternative to produce biodiesel.

Highlights

Nowadays, searching for a renewable and alternative energy source is an important task due to the continuous increase in energy demand, the depletion of fossil fuel resources, the global warming, and the environmental pollution. e biodiesel (BD), fatty acid methyl esters (FAMEs), has been accepted worldwide as a renewable fuel alternative to the fossil diesel [1]
Basic homogeneous catalysts are frequently used for the transesterification of triglycerides in an industrial scale. These catalysts have serious disadvantages; for example, they are neither recyclable nor environmentally friendly and lead to formation of biodiesel and glycerol contaminated with sodium or potassium ions [14, 15] and they produce soaps. These catalysts are deactivated when the feedstock presents a humidity level of more than 0.3 wt.% and/or the free fatty acid (FFA) level are higher than 0.5 wt.% [16]. erefore, the use of homogeneous catalysts to produce biodiesel requires very pure raw materials. e nonedible oils, animal fat, cooking oils, or waste oils used as raw materials for the International Journal of Chemical Engineering biodiesel production are less expensive than edible oils and reduce the cost of biodiesel production [17,18,19,20]
Afterwards, the obtained solid was calcined at 850°C in a muffle. e catalyst synthesis was performed from ambient temperature to 100°C with a heating rate of 4°C·min−1; in a first plateau, the sample was kept at 100°C during 75 minutes and the temperature was raised to 850°C at 3.5°C·min−1

Summary

Introduction

Nowadays, searching for a renewable and alternative energy source is an important task due to the continuous increase in energy demand, the depletion of fossil fuel resources, the global warming, and the environmental pollution. e biodiesel (BD), fatty acid methyl esters (FAMEs), has been accepted worldwide as a renewable fuel alternative to the fossil diesel [1]. Basic homogeneous catalysts (sodium hydroxides or alkoxides) are frequently used for the transesterification of triglycerides in an industrial scale These catalysts have serious disadvantages; for example, they are neither recyclable nor environmentally friendly and lead to formation of biodiesel and glycerol contaminated with sodium or potassium ions [14, 15] and they produce soaps. These catalysts are deactivated when the feedstock presents a humidity level of more than 0.3 wt.% and/or the free fatty acid (FFA) level are higher than 0.5 wt.% [16]. A simple synthesis of CaO-ZnO catalysts, in only one step, is proved

Methods

Results

Conclusion