Abstract
Some of the more recent methods to produce biodiesel are based on heterogeneous catalysis, which has the advantage of easy separation of catalyst from the final product. In this paper, the heterogeneous transesterification of rapeseed oil with methanol is studied. The aim of this work was to investigate the possibilities of using natural catalysts in biodiesel synthesis and to determine the optimal conditions for this process. After the evaluation of catalytic effectiveness of rocks containing calcium and magnesium carbonates, it was determined that dolomite is the most effective catalyst in heterogeneous biodiesel synthesis. The optimal conditions of dolomite preparation are the following: heating at 850 °C for 5 h. The rapeseed oil transesterification was optimized by the application response surface methodology. Optimal conditions for the production of rapeseed methyl esters using dolomite as catalyst are the following: molar ratio of methanol to rapeseed oil of 11.94:1, reaction temperature of 64 °C, dolomite content of 6 wt%, reaction time of 5 h.
Highlights
IntroductionAlternative fuels of biological origin, e.g., ethanol, biodiesel, have been intensively explored in recent decades
Given the rather contradictory results in the scientific literature on the efficiency of using rocks as heterogeneous catalysts for biodiesel synthesis, the very different reported optimal conditions for transesterification, and the need to look for cheaper natural heterogeneous catalysts for biodiesel synthesis, our work focused on rocks found in our country that contain Ca and Mg compounds
In order to evaluate the catalytic efficiency of natural rocks in the transesterification process, studies using selected rocks were performed under uniform conditions
Summary
Alternative fuels of biological origin, e.g., ethanol, biodiesel, have been intensively explored in recent decades. The high consumption of fossil fuels, the impact on global warming, and concerns about the depletion of energy resources are key aspects that stimulate interest in biofuels. The biodiesel production process can be heterogeneous when the catalyst is in a different phase than the reactant and reaction product, homogeneous when the catalyst is in the same phase, and enzymatic (enzymes can be used both liquid and solid) [1]. Heterogeneous catalysis is considered more environmentally friendly because the solid catalyst is separated from the reaction mixture by filtration and can be reused [2]. The reagents are adsorbed on the surface of the catalyst, where a transesterification reaction takes place, and the product is desorbed. Heterogeneous catalysts can be designed to be more active and selective than homogeneous ones, as well as to be used over a longer period of time—reusable
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