Ivana Lukić

Alumina/silica supported K2CO3 as a catalyst for biodiesel synthesis from sunflower oil.

The new type of catalyst for fatty acid methyl esters (FAME or biodiesel) synthesis with K(2)CO(3) as active component on alumina/silica support was synthesized using sol-gel method. Corresponding catalyst (xerogel) was prepared by 12h drying the wet gel in air at 300 degrees C, 600 degrees C or 1000 degrees C at atmospheric pressure. The catalysts activity in the methanolysis of sunflower oil was compared to the activity of the pure K(2)CO(3). The effects of various reaction variables on the yield of FAME were investigated. It was found that the temperature of 120 degrees C and methanol to oil molar ratio of 15:1, are optimal conditions for FAME synthesis with synthesized catalyst. Repeated use of same amount of catalyst indicated that effect of potassium leaching obviously existed leading to decrease of catalyst activity.

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.

Kinetics of heterogeneous methanolysis of sunflower oil with CaO∙ZnO catalyst: Influence of different hydrodynamic conditions

The kinetics of heterogeneous methanolysis of sunflower oil was studied at 60°C using mechanochemically synthesized CaO∙ZnO as catalyst. Influence of agitation speed, catalyst amount and methanol to oil molar ratio on the rate of reaction was analyzed. The rate of the process depends on the two resistances - mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as the values of the overall triglyceride volumetric mass transfer coefficient, kmt,TG, and the effective pseudo first-order reaction rate constant, k, respectively. These kinetic parameters actually determine the value of the apparent reaction rate constant, kapp, whose change with time is defined with the change of triglyceride (TG) conversion. The kinetic model was proposed and the model parameters determined. [Projekat Ministarstva nauke Republike Srbije, br. 45001]

Heterogeneous base-catalyzed methanolysis of vegetable oils: State of art

Today, homogeneous base-catalyzed methanolysis is the most frequently used method for industrial biodiesel production. High requirements for the quality of the feedstocks and the problems related to the huge amount of wastewaters have led to the development of novel biodiesel production technologies. Among them, the most important is heterogeneous base-catalyzed methanolysis, which has been intensively investigated over the last decade in order to develop new catalytic systems, optimize the reaction conditions and to recycle catalysts. These studies are a basis for continuous development of biodiesel production on an industrial scale in the near future. The presented work summarize up-to-date studies on biodiesel production by heterogeneous base-catalyzed methanolysis. The main goals were to point out the application of different base compounds as catalysts, the methods of catalyst preparation, impregnation on carriers and recycling as well as the possibilities to improve existing base-catalyzed biodiesel production processes and to develop novel ones.

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.

Relation between creativity and planned regulation in the process of shaping urban skyline

The subject matter of this paper belongs to multidisciplinary field consisted primary of urbanism and a part of it – urban design, as well as architecture and other fields, like aesthetics, psychology and economy, which supplement certain standpoints. Urban skyline of cities or large parts of the cities, as urban macro-images, are considered in relation to the nature of their origin – self-generated or being effect of the plan, through phenomenon of visual experience and application of new technologies on facades. The question is which ratio of creativity and planned regulation is optimal in the process of creating visually concur- rent urban skylines. If planned solution of total macro-image is done well, the answer is: all regulations should be kept and creativity has no limits. In other cases, it is necessary to establish flexible scope of regulations, so that single elements of urban skyline could be realized in balance between limitations and desired result.