The Experts below are selected from a list of 61632 Experts worldwide ranked by ideXlab platform
Ayhan Demirbas - One of the best experts on this subject based on the ideXlab platform.
-
comparison of Transesterification methods for production of biodiesel from vegetable oils and fats
Energy Conversion and Management, 2008Co-Authors: Ayhan DemirbasAbstract:Abstract Comparative studies on Transesterification methods were presented in this work. Biodiesel is obtained from a chemical reaction called Transesterification (ester exchange). The reaction converts esters from long chain fatty acids into mono alkyl esters. Chemically, biodiesel commonly is a fatty acid methyl ester. Vegetable oils can be transesterified by heating them with a large excess of anhydrous methanol and an acidic or basic reagent as catalyst. A catalyst is usually used to improve the reaction rate and yield. In a Transesterification reaction, a larger amount of methanol was used to shift the reaction equilibrium to the right side and produce more methyl esters as the proposed product. Several aspects including the type of catalyst (alkaline, acid or enzyme), alcohol/vegetable oil molar ratio, temperature, purity of the reactants (mainly water content) and free fatty acid content have an influence on the course of the Transesterification. A non-catalytic biodiesel production route with supercritical methanol has been developed that allows a simple process and high yield because of the simultaneous Transesterification of triglycerides and methyl esterification of fatty acids. In the catalytic supercritical methanol Transesterification method, the yield of conversion rises to 60–90% for the first 1 min.
-
biodiesel from sunflower oil in supercritical methanol with calcium oxide
Energy Conversion and Management, 2007Co-Authors: Ayhan DemirbasAbstract:In this study, sunflower seed oil was subjected to the Transesterification reaction with calcium oxide (CaO) in supercritical methanol for obtaining biodiesel. Methanol is used most frequently as the alcohol in the Transesterification process. Calcium oxide (CaO) can considerably improve the Transesterification reaction of sunflower seed oil in supercritical methanol. The variables affecting the methyl ester yield during the Transesterification reaction, such as the catalyst content, reaction temperature and the molar ratio of soybean oil to alcohol, were investigated and compared with those of non-catalyst runs. The catalytic Transesterification ability of CaO is quite weak under ambient temperature. At a temperature of 335 K, the yield of methyl ester is only about 5% in 3 h. When CaO was added from 1.0% to 3.0%, the Transesterification speed increased evidently, while when the catalyst content was further enhanced to 5%, the yield of methyl ester slowly reached to a plateau. It was observed that increasing the reaction temperature had a favorable influence on the methyl ester yield. In addition, for molar ratios ranging from 1 to 41, as the higher molar ratios of methanol to oil were charged, the greater Transesterification speed was obtained. When the temperature was increased to 525 K, the Transesterification reaction was essentially completed within 6 min with 3 wt% CaO and 41:1 methanol/oil molar ratio.
-
biodiesel production facilities from vegetable oils and animal fats
Energy Sources Part A-recovery Utilization and Environmental Effects, 2007Co-Authors: Ayhan Demirbas, S KarsliogluAbstract:Abstract Biodiesel is a renewable fuel that can be produced from vegetable oils, animal fats, and used cooking oil including triglycerides. Biodiesel, an alternative biodegradable diesel fuel, is derived from triglycerides by Transesterification with methanol and ethanol. Concerns about the depletion of diesel fuel reserves and the pollution caused by continuously increasing energy demands make biodiesel an attractive alternative motor fuel for compression ignition engines. There are four different ways of modifying vegetable oils and fats to use them as diesel fuel, such as pyrolysis (thermal cracking), dilution with hydrocarbons (blending), emulsification and Transesterification. The most commonly used process is Transesterification of vegetable oils and animal fats. The Transesterification reaction is affected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. In the Transesterification, free fatty acids and wa...
-
biodiesel production via non catalytic scf method and biodiesel fuel characteristics
Energy Conversion and Management, 2006Co-Authors: Ayhan DemirbasAbstract:Abstract Vegetable oil (m)ethyl esters, commonly referred to as “biodiesel,” are prominent candidates as alternative Diesel fuels. Biodiesel is technically competitive with or offers technical advantages compared to conventional petroleum Diesel fuel. The vegetable oils, as alternative engine fuels, are all extremely viscous with viscosities ranging from 10 to 20 times greater than that of petroleum Diesel fuel. The purpose of the Transesterification process is to lower the viscosity of the oil. Transesterifications of vegetable oils in supercritical methanol are performed without using any catalyst. The most important variables affecting the methyl ester yield during the Transesterification reaction are the molar ratio of alcohol to vegetable oil and the reaction temperature. Biodiesel has become more attractive recently because of its environmental benefits. The cost of biodiesel, however, is the main obstacle to commercialization of the product. With cooking oils used as raw material, the viability of a continuous Transesterification process and recovery of high quality glycerol as a biodiesel by product are primary options to be considered to lower the cost of biodiesel. Supercritical methanol has a high potential for both Transesterification of triglycerides and methyl esterification of free fatty acids to methyl esters for a Diesel fuel substitute. In the supercritical methanol Transesterification method, the yield of conversion increases to 95% in 10 min. The viscosity values of vegetable oils are between 27.2 and 53.6 mm 2 /s, whereas those of vegetable oil methyl esters are between 3.59 and 4.63 mm 2 /s. The flash point values of vegetable oil methyl esters are much lower than those of vegetable oils. An increase in density from 860 to 885 kg/m 3 for vegetable oil methyl esters or biodiesels increases the viscosity from 3.59 to 4.63 mm 2 /s. Biodiesel is an environmentally friendly fuel that can be used in any Diesel engine without modification.
-
biodiesel production from vegetable oils via catalytic and non catalytic supercritical methanol Transesterification methods
Progress in Energy and Combustion Science, 2005Co-Authors: Ayhan DemirbasAbstract:Abstract This paper reviews the production and characterization of biodiesel (BD or B) as well as the experimental work carried out by many researchers in this field. BD fuel is a renewable substitute fuel for petroleum diesel or petrodiesel (PD) fuel made from vegetable or animal fats. BD fuel can be used in any mixture with PD fuel as it has very similar characteristics but it has lower exhaust emissions. BD fuel has better properties than that of PD fuel such as renewable, biodegradable, non-toxic, and essentially free of sulfur and aromatics. There are more than 350 oil bearing crops identified, among which only sunflower, safflower, soybean, cottonseed, rapeseed and peanut oils are considered as potential alternative fuels for diesel engines. The major problem associated with the use of pure vegetable oils as fuels, for Diesel engines are caused by high fuel viscosity in compression ignition. Dilution, micro-emulsification, pyrolysis and Transesterification are the four techniques applied to solve the problems encountered with the high fuel viscosity. Dilution of oils with solvents and microemulsions of vegetable oils lowers the viscosity, some engine performance problems still exist. The viscosity values of vegetable oils vary between 27.2 and 53.6 mm 2 /s whereas those of vegetable oil methyl esters between 3.59 and 4.63 mm 2 /s. The viscosity values of vegetable oil methyl esters highly decreases after Transesterification process. Compared to no. 2 diesel fuel, all of the vegetable oil methyl esters were slightly viscous. The flash point values of vegetable oil methyl esters are highly lower than those of vegetable oils. An increase in density from 860 to 885 kg/m 3 for vegetable oil methyl esters or biodiesels increases the viscosity from 3.59 to 4.63 mm 2 /s and the increases are highly regular. The purpose of the Transesterification process is to lower the viscosity of the oil. The transesterfication of triglycerides by methanol, ethanol, propanol and butanol, has proved to be the most promising process. Methanol is the commonly used alcohol in this process, due in part to its low cost. Methyl esters of vegetable oils have several outstanding advantages among other new-renewable and clean engine fuel alternatives. The most important variables affecting the methyl ester yield during the Transesterification reaction are molar ratio of alcohol to vegetable oil and reaction temperature. Biodiesel has become more attractive recently because of its environmental benefits. Biodiesel is an environmentally friendly fuel that can be used in any diesel engine without modification.
Piyasan Praserthdam - One of the best experts on this subject based on the ideXlab platform.
-
Reaction Kinetics and Mechanisms for Hydrolysis and Transesterification of Triglycerides on Tungstated Zirconia
Topics in Catalysis, 2010Co-Authors: Kanokwan Ngaosuwan, Xunhua Mo, James G. Goodwin, Piyasan PraserthdamAbstract:Hydrolysis and Transesterification are two reactions which can occur during the synthesis of biodiesel. An Investigation of the mechanistic pathways in hydrolysis and Transesterification were carried out at a relatively high temperature (100–130 °C) and moderate pressures (120–180 psi) with tricaprylin and water for hydrolysis or methanol for Transesterification using a tungstated zirconia catalyst in a batch reactor. It was found that upon increasing the concentration of TCp, the reaction rates for both hydrolysis and Transesterification increased at all conditions. In contrast, water inhibited the reaction rate of hydrolysis by poisoning the active sites. For Transesterification, the apparent reaction order of methanol evolved from positive to negative as the concentration of methanol relative to TCp increased. Using a reaction model discrimination procedure, it was found that hydrolysis on WZ could be successfully described by an Eley–Rideal single site mechanism with adsorbed TCp reacting with bulk phase water. The mechanistic pathway for Transesterification also seems to follow a similar mechanism, identical to the one previously proposed for Transesterification on a solid acid catalyst (SiO_2-supported Nafion-SAC-13) at lower temperature (60 °C).
-
Reaction Kinetics and Mechanisms for Hydrolysis and Transesterification of Triglycerides on Tungstated Zirconia
Topics in Catalysis, 2010Co-Authors: Kanokwan Ngaosuwan, James G. Goodwin, Piyasan PraserthdamAbstract:Hydrolysis and Transesterification are two reactions which can occur during the synthesis of biodiesel. An Investigation of the mechanistic pathways in hydrolysis and Transesterification were carried out at a relatively high temperature (100–130 °C) and moderate pressures (120–180 psi) with tricaprylin and water for hydrolysis or methanol for Transesterification using a tungstated zirconia catalyst in a batch reactor. It was found that upon increasing the concentration of TCp, the reaction rates for both hydrolysis and Transesterification increased at all conditions. In contrast, water inhibited the reaction rate of hydrolysis by poisoning the active sites. For Transesterification, the apparent reaction order of methanol evolved from positive to negative as the concentration of methanol relative to TCp increased. Using a reaction model discrimination procedure, it was found that hydrolysis on WZ could be successfully described by an Eley–Rideal single site mechanism with adsorbed TCp reacting with bulk phase water. The mechanistic pathway for Transesterification also seems to follow a similar mechanism, identical to the one previously proposed for Transesterification on a solid acid catalyst (SiO2-supported Nafion-SAC-13) at lower temperature (60 °C).
Michael G. Kontominas - One of the best experts on this subject based on the ideXlab platform.
-
in situ Transesterification of cynara cardunculus l seed oil via direct ultrasonication for the production of biodiesel
Fuel Processing Technology, 2015Co-Authors: A A Koutsouki, Evangelia Tegou, Stavros Kontakos, Philippos J Pomonis, Michael G. Kontominas, George ManosAbstract:Abstract Alkaline Transesterification of Cynara cardunculus L. seed oil with methanol for biodiesel production is investigated. Both in situ Transesterification and conventional Transesterification were studied using ultrasonication (24 kHz, without external heating) and mechanical stirring (600 rpm, 60 °C). For in situ Transesterification, the use of ultrasonication and mechanical stirring led to similar high % FAME content (96.0 and 93.0% respectively) after 20 min. However the % yield of the extracted methylesters using mechanical stirring was lower compared to ultrasonication (50.4 and 85.1% respectively). For in situ Transesterification via ultrasonication the optimum conditions were: 9.5% NaOH w/w of oil and a 550:1 methanol to oil molar ratio. In conventional Transesterification, using ultrasonication, a high % FAME content of methylesters (97.0%) was obtained after 20 min. Respective % FAME content for mechanical stirring was 95.8% after 1 h. In both cases of conventional Transesterification 1% w/w of oil NaOH as catalyst and a 7:1 methanol to oil ratio were used. The kinetics used for methanolysis reaction using sonication or mechanical stirring involved the irreversible second order reaction followed by the reversible second order reaction close to equilibrium. Cynara biodiesel properties determined, comply with the specifications of the European Standard EN 14214.
-
conventional and in situ Transesterification of sunflower seed oil for the production of biodiesel
Fuel Processing Technology, 2008Co-Authors: K G Georgogianni, D Avlonitis, Philippos J Pomonis, Michael G. Kontominas, V GergisAbstract:Abstract In the present work the alkaline Transesterification of sunflower seed oil with methanol and ethanol, for the production of biodiesel fuel was studied. Both conventional and in situ Transesterification were investigated using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm). Use of ultrasonication in conventional Transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Use of ultrasonication in conventional Transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ Transesterification the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol use of ultrasonication led to high ester yields (98%) in only 40 min of reaction time while use of mechanical stirring gave lower yields (88%) even after 4 h of reaction time. In situ Transesterification gave similar ester yields to those obtained by conventional Transesterification being an alternative, efficient and economical process. In all cases a concentration of 2.0% NaOH gave higher ester yields. Reaction rate constants were calculated, using first order reaction kinetics, to be equal to 3.1 × 10 − 3 s − 1 for conventional Transesterification using methanol and 2.0% NaOH, and 9.5 × 10 − 4 s − 1 using ethanol.
-
Alkaline Conventional and in Situ Transesterification of Cottonseed Oil for the Production of Biodiesel
Energy & Fuels, 2008Co-Authors: K G Georgogianni, D Avlonitis, Philippos J Pomonis, Michael G. Kontominas, V GergisAbstract:In the present work, the Transesterification of cottonseed oil with methanol and ethanol, in the presence of alkali catalyst (NaOH), using low-frequency ultrasonication (24 KHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Both conventional and in situ Transesterification were investigated. Use of ultrasonication in conventional Transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Higher concentrations of NaOH (2.0%) gave higher ester yields. Use of ultrasonication in conventional Transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ Transesterification, the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol, use of ultrasonication led to hi...
Sandun Fernando - One of the best experts on this subject based on the ideXlab platform.
-
reaction kinetics of soybean oil Transesterification using heterogeneous metal oxide catalysts
Chemical Engineering & Technology, 2007Co-Authors: Alok Kumar Singh, Sandun FernandoAbstract:Homogeneous acid or base catalysts dissolve fully in the glycerol layer and partially in the fatty acid methyl ester (biodiesel) layer in the triglyceride Transesterification process. Heterogeneous (solid) catalysts, on the other hand, can prevent catalyst contamination making product separation much simpler. In the present work, the Transesterification kinetics of five different solid catalysts with soybean oil is presented. It is found that heterogeneous catalysts require much higher temperatures and pressures to achieve acceptable conversion levels compared to homogeneous catalysts. Subsequent to preliminary investigations, Transesterifications were conducted for selected high performance solid catalysts, i.e., MgO, CaO, BaO, PbO, and MnO2 in a high pressure reactor up to a temperature of 215 °C. The yield of the fatty acid methyl esters and the kinetics (rate constant and order) of the reaction are estimated and are compared for each catalyst.
Kanokwan Ngaosuwan - One of the best experts on this subject based on the ideXlab platform.
-
Reaction Kinetics and Mechanisms for Hydrolysis and Transesterification of Triglycerides on Tungstated Zirconia
Topics in Catalysis, 2010Co-Authors: Kanokwan Ngaosuwan, Xunhua Mo, James G. Goodwin, Piyasan PraserthdamAbstract:Hydrolysis and Transesterification are two reactions which can occur during the synthesis of biodiesel. An Investigation of the mechanistic pathways in hydrolysis and Transesterification were carried out at a relatively high temperature (100–130 °C) and moderate pressures (120–180 psi) with tricaprylin and water for hydrolysis or methanol for Transesterification using a tungstated zirconia catalyst in a batch reactor. It was found that upon increasing the concentration of TCp, the reaction rates for both hydrolysis and Transesterification increased at all conditions. In contrast, water inhibited the reaction rate of hydrolysis by poisoning the active sites. For Transesterification, the apparent reaction order of methanol evolved from positive to negative as the concentration of methanol relative to TCp increased. Using a reaction model discrimination procedure, it was found that hydrolysis on WZ could be successfully described by an Eley–Rideal single site mechanism with adsorbed TCp reacting with bulk phase water. The mechanistic pathway for Transesterification also seems to follow a similar mechanism, identical to the one previously proposed for Transesterification on a solid acid catalyst (SiO_2-supported Nafion-SAC-13) at lower temperature (60 °C).
-
Reaction Kinetics and Mechanisms for Hydrolysis and Transesterification of Triglycerides on Tungstated Zirconia
Topics in Catalysis, 2010Co-Authors: Kanokwan Ngaosuwan, James G. Goodwin, Piyasan PraserthdamAbstract:Hydrolysis and Transesterification are two reactions which can occur during the synthesis of biodiesel. An Investigation of the mechanistic pathways in hydrolysis and Transesterification were carried out at a relatively high temperature (100–130 °C) and moderate pressures (120–180 psi) with tricaprylin and water for hydrolysis or methanol for Transesterification using a tungstated zirconia catalyst in a batch reactor. It was found that upon increasing the concentration of TCp, the reaction rates for both hydrolysis and Transesterification increased at all conditions. In contrast, water inhibited the reaction rate of hydrolysis by poisoning the active sites. For Transesterification, the apparent reaction order of methanol evolved from positive to negative as the concentration of methanol relative to TCp increased. Using a reaction model discrimination procedure, it was found that hydrolysis on WZ could be successfully described by an Eley–Rideal single site mechanism with adsorbed TCp reacting with bulk phase water. The mechanistic pathway for Transesterification also seems to follow a similar mechanism, identical to the one previously proposed for Transesterification on a solid acid catalyst (SiO2-supported Nafion-SAC-13) at lower temperature (60 °C).
