A sustainable process for biodiesel production using Zn/Mg oxidic species as active, selective and reusable heterogeneous catalysts

Marisa B Navas,José F Ruggera,Mónica L Casella,Ileana D Lick

doi:10.1186/s40643-019-0291-3

Abstract

This paper describes the preparation and characterization of MgO and ZnO-based catalysts, pure and mixed in different proportions, supported on γ-Al2O3. Their catalytic performance was studied in the transesterification of soybean oil and castor oil with methanol and butanol, attempting to produce biodiesel. XRD (X-ray diffraction), SEM–EDS (scanning electron microscopy–energy dispersive X-ray spectroscopy), CO2-adsorption and N2-adsorption allowed characterizing the prepared catalysts. The characterization results were in all cases consistent with mesoporous solids with high specific surface area. All the catalysts exhibited good results, especially in the transesterification of castor oil using butanol. For this reaction, the reuse was tested, maintaining high FABE (fatty acid butyl esters) yields after four cycles. This good performance can be attributed to the basic properties of the Mg species, and simultaneously, to the amphoteric properties of ZnO, which allow both triglycerides and free fatty acids to be converted into esters. Using these catalysts, it is possible to obtain second-generation biodiesel, employing castor oil, a raw material that does not compete with the food industry. In addition, butanol can be produced from renewable biomass.

Highlights

The growing demands of energy in sectors such as transport or various industries, require the need for replacement of non-renewable fossil fuels
Catalyst characterization The elemental composition of the catalysts was determined by atomic absorption spectroscopy (AAS)
ZnO/γAl2O3 catalyst presented a value of 67 Å, a considerably higher value than that observed for MgO/γ-Al2O3 catalyst and the Zn/Mg mixtures, that range between 52 and 57 Å

Summary

Introduction

The growing demands of energy in sectors such as transport or various industries, require the need for replacement of non-renewable fossil fuels. Renewable fuels appear as an attractive option to satisfy this demand. There is a classification for these biofuels, which include: first generation, those produced from highly available food sources; second generation, those generated using non-edible raw materials or involving advanced technologies; third generation, including biofuels from algae; and fourth generation, those. Biodiesel attracted much attention as alternative energy source, since it is renewable, sustainable and biodegradable. Biodiesel can be produced in a cleaner and less expensive way, using advanced technologies and waste sources, like biowaste oil (Chuah et al 2017)

Methods

Results

Conclusion