Sandra B. Glisic

Biodiesel synthesis at high pressure and temperature: analysis of energy consumption on industrial scale.

Analysis of several different schemes for industrial FAME production at higher pressure and temperature (catalytic or non-catalytic synthesis) was realized with the aim to find the best route to reduce the energy consumption (EC) and to improve the life cycle energy efficiency. Obtained results indicated that the EC (MJ/kg FAME) mainly depends on degree of conversion of triglycerides being almost 25% smaller if degree of conversion increase from 97 mass% to complete conversion. Further significant decrease of EC might be obtained at subcritical conditions but only after substantial decrease of methanol to oil molar ratio (from 42 to 15) which requires use of appropriate catalyst. On account of that, the kinetics of heterogeneous catalyzed methanolysis of triglycerides was analyzed using data published in literature (CaO) as well as own experimental data (K(2)CO(3)/Al-O-Si) with a goal to obtain reliable kinetic rate constant which might be used for process simulation. This study shows that if heterogeneous process of biodiesel synthesis is realized at subcritical conditions then further decrease of EC is possible.

The combined extraction of sage (Salvia officinalis L.): ultrasound followed by supercritical CO2 extraction.

A wide spectrum of phytochemicals could be isolated from sage (Salvia officinalis L.) using different extraction or distillation technique: the supercritical fluid extraction (SFE), the volatiles compounds (monoterpenes and sesquiterpenes) isolation using hydrodistillation or higher molecular compounds with Soxhlet extraction or ultrasound-assisted extraction. The combination of ultrasound-assisted extraction followed by re-extraction of obtained extract with supercritical CO(2) was performed in this study. The goal of performed investigation was to concentrate diterpenes present in sage extract which are generally considered to be responsible for antioxidant activity of extracted compounds. The fractionation using the supercritical CO(2), and different combination of the ultrasound-assisted solvent extractions (water-ethanol mixture or only water) followed by supercritical CO(2) re-extraction of obtained extract or treated plant material were analyzed and compared. Based on the results of these investigations it could be proposed the best extraction procedure: the ultrasound pretreatment of plant material with distilled water and re-extraction of plant material (residue) using supercritical CO(2). That procedure gives two valuable products: the ultrasound extract which is rich in sugars and possess the immunomodulatory activity and supercritical extract which is rich in diterpenes and sesquiterpenes.

BIODIESEL II. A new concept of biodiesel production - transesterification with supercritical methanol.

Biodiesel is defined as a fuel that might be used as a pure biofuel or at high concentration in mineral oil derivatives, in accordance with specific quality standards for transport applications. The main raw material used for biodiesel production is rapeseed, which contains mono-unsaturated (about 60%) and also, in a lower quantity, poly-unsaturated fatty acids (C 18:1 and C 18:3), as well as some amounts of undesired saturated fatty acids (palmitic and stearic acids). Other raw materials have also been used in the research and industrial production of biodiesel (palm-oil, sunflower-oil, soybean-oil, waste plant oil, animal fats, etc). The historical background of the biodiesel production, installed industrial capacities, as well as Directives of the European Parliament and of the Council (May 2003) regarding the promotion of the use of biofuels or other renewable fuels for transport are discussed in the first part of this article (Chem. Ind. 58 (2004)). The second part focused on some new concepts and the future development of technology for biodiesel production based on the use of non-catalytic transesterification under supercritical conditions. A literature review, as well as original results based on the transesterification of animal fats, plant oil and used plant oil were discussed. Obtained results were compared with the traditional concept of transesterification based on base or acid catalysis. Experimental investigations of transesterification with supercritical methanol were performed in a 2 dm3 autoclave at 140 bar pressure and at 300°C with molar ratio of methanol to triglycerides of about 41. The degree of esterification strongly depends on the density of supercritical methanol and on the possibility of reaction occurring in one phase.

Biodiesel I: Historical background, present and future production and standards - professional paper

Biodiesel is defined as a fuel which may be used as pure biofuel or at high concentration in mineral oil derivatives, in accordance with specific quality standards for transport applications. The main raw material used for biodiesel production is rapeseed, which contains mono-unsaturated acids (about 60%) and also poly-unsaturated fatty acids (C 18:1 and C 18:3) in a lower quantity, as well as some undesired saturated fatty acids (palmitic and stearic acids). Other raw materials have also been used in research and the industrial production of biodiesel (palm oil, sunflower oil, soybean oil, waste plant oil, animal fats, etc). The historical background of biodiesel production, installed industrial capacities, as well as the Directive of the European Parliament and of the Council (May 2003) regarding the promotion of the use of biofuels or other renewable fuels for transport are discussed in the first part of this article. The second part focuses on some new concepts for the future development of technology for biodiesel production, based on the application of non-catalytic transesterification under supercritical conditions or the use of lipases as an alternative catalyst for this reaction.