In this study, low-quality rapeseed was used as a raw material for biodiesel fuel production. The application of such seeds with an enzyme catalyst is a green approach to producing renewable biodiesel fuel. During the in situ transesterification process, mineral diesel was selected as an extraction solvent for the simultaneous extraction and transesterification of rapeseed oil (RO). This allowed, at the end of the process, for the production of a mixture of mineral diesel and biodiesel fuel. Energy is saved using this process, as the need to extract the oil separately is eliminated and extraction and transesterification take place together in the in situ process. In this study, 11 different lipases were analyzed from which to select the most effective biocatalyst according to the chosen experimental conditions. The most suitable lipase for in situ transesterification was Lipozyme TL IM (Thermomyces lanuginosus). The impact of the temperature and duration of the reaction was investigated along with the concentration of the lipase. A ethanol-to-oil molar ratio of 5:1 was chosen. The optimal reaction conditions were as follows: a reaction duration of 7 h, a reaction temperature of 30 °C and a lipase concentration of 5% (based on oil weight). Under these conditions, 99.92% of oil was extracted from the rapeseed. The degree of oil transesterification acquired was 99.89%. A mineral diesel and rapeseed oil ethyl ester blend of 9:1 (w/w) was produced.

Recently, there has been a growing interest in the use of new types of cheaper raw materials for biodiesel production. There are many prospects for microalgae, which do not compete for land with conventional biodiesel raw materials, are characterized by rapid reproduction and high biomass accumulation, and under certain conditions, some are able to accumulate a large amount of oil. A number of studies have been conducted on the extraction of oil from microalgae cells and transesterification with various acyl receptors. This paper provides an overview of the results of research on microalgal biomass preparation and oil extraction. Indicators of the quality of the oil are presented and its suitability for biodiesel synthesis is analyzed. The homogeneous and heterogeneous catalysts used for oil transesterification are described and the optimal conditions of the process when using various alcohols as acyl receptors are presented. Much attention is paid to the parameters affecting the transesterification efficiency and biodiesel yield. The physical and chemical, and operational and environmental properties of biodiesel obtained from algae oil are analyzed. The evaluation of the economic efficiency of biodiesel synthesis is also presented.

Increasing concentrations of greenhouse gases in the atmosphere are leading to increased production and use of biofuels. The industrial development of biodiesel production and the use of biodiesel in the EU transport sector have been ongoing for almost two decades. Compared to mineral diesel production, the process of producing biodiesel is quite complex and expensive, and the search for new raw materials and advanced technologies is needed to maintain production value and expand the industrial production of biodiesel. The purpose of this article is to review the application possibilities of one of the new technologies—simultaneous extraction of oil from oily feedstock and transesterification (in situ)—and to evaluate the effectiveness of the abovementioned process under various conditions.

Homogeneous catalysis is relevant for biodiesel fuel synthesis; however, it has the disadvantage of difficult separation of the catalyst. In the present work, heterogeneous catalysis was applied for rapeseed oil transesterification with methanol, while snail shells were used as a catalyst. CaO content in the catalyst was investigated. Transesterification reactions were carried out in a laboratory reactor, ester yield was analyzed using gas chromatography. Response surface methodology was used for process optimization. It was found that the optimum transesterification conditions when the reaction temperature is 64 °C are the following: a catalyst amount of 6.06 wt%, a methanol-to-oil molar ratio of 7.51:1, and a reaction lasting 8 h. An ester yield of 98.15 wt% was obtained under these conditions.

Heterogeneous catalysis has an advantage of easy separation of the catalyst after biodiesel is produced. CaO is known to be an efficient heterogeneous catalyst for biodiesel production. Taking into account that CaO is a key component of eggshells, the effectiveness of eggshells as a heterogeneous catalyst for rapeseed oil transesterification with methanol was investigated and optimal conditions of biodiesel production were determined applying RSM methodology. The influence of three independent variables on ester content was analyzed and a quadratic model was created. It was determined that this model is statistically significant. The optimum transesterification conditions when eggshells are used as a heterogeneous catalyst, and the process temperature of 64 °C, were determined as: the methanol-to-oil molar ratio 10.93:1; the catalyst amount 6.80 wt%; the reaction duration 9.48 h. The ester yield of 97.79 wt% was obtained under these conditions.

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.