Synthesis of biodiesel from triglyceride oil - CORE

Most researchers believe that the effect of ultrasonication on enhancing transesterification lies mainly in intensifying the mixing of the immiscible methanol and triglyceride phases, especially at the beginning of the reaction. The mixing enhancement is largely due to the collapse of ultrasonic cavitation bubbles and the reduced droplet sizes of low boiling temperature methanol in less-miscible triglycerides (; ). Another observation was that the ultrasonication does not affect the ester profiles as compared with those from conventional, non-ultrasonication procedures if potassium is used as the catalyst, indicating that ultrasonication does not decompose s to other chemicals (e.g., radicals) as observed in other organic systems (). On the other hand, results of improved separation were observed under ultrasonication when sodium hydroxide was used as the catalyst (). The catalysts after ultrasonication maintain their physical and and can be reused without significant deactivation. Ultrasonication also showed effectiveness for transesterification catalyzed by enzymes. Under optimized conditions (50% of ultrasonic power or approximately equivalent to 7200 kJ energy input per liter of reacting mixture, 50 rpm vibration, 6% Novozym 435 and 40°C), 96% yield of biodiesel from soy bean oil was achieved in 4 h and the enzyme showed no obvious activity loss (; ). have reported that to maximize the ultrasonication effect, a combination of lower frequencies at higher intensity of irradiation was preferred over higher frequencies and lower intensities of irradiation. The authors commented that higher intensity of ultrasonication is preferred but an optimum intensity must be observed due to the phenomena of that states that when large amount of ultrasonic power enters a system, a much larger quantity of ultrasonic cavitation bubbles is generated in the solution. Excessive bubbles likely merge and form larger and more stable bubbles and, thus, create a barrier to acoustic energy transfer (; ; ).

Synthesis of biodiesel from waste vegetable oil with …

Calaméo - Synthesis of Biodiesel From Waste Vegetable …

Synthesis of Biodiesel from Canola Oil Using …

The introduction of non-catalytic means to produce biodiesel using supercritical methanol via the one step method and two step method (, ) has triggered many further research works utilizing wide range of raw materials or with certain improvements and modifications in the recent years. Up to now, non-catalytic biodiesel conversion methods have been limited to the use of supercritical conditions (i.e., temperatures above 250°C and pressures above 10 MPa). However, the supercritical conditions used to drive the reaction gave rise to high operational and equipment costs. In this regard, noncatalytic biodiesel conversion with the conditions under ambient pressure must be developed. developed an alternative new process with other potential reactants such as methyl formate and methyl acetate of carboxylate esters to produce methyl esters (biodiesel) with triacin from oils and fats without producing glycerol. Similarly non-catalytic supercritical dimethyl carbonate (DMC) method has been developed by , based on the direct transesterification of triglycerides with dimethyl carbonate at the condition of 350°C and 20 MPa. In the study, dimethyl carbonate rather than methanol was selected as a reactant for non-catalytic supercritical treatment. The authors have reported a yield of 97.4% was achieved using conditions of 300°C and 20 MPa for 20 min with a molar ratio of DMC to lipid feedstock of 42:1 via a batch system. As shown in , the byproduct of the transesterification reaction with DMC is glycerol dicarbonate. In general, DMC is a versatile chemical due to its eco-friendliness, chemical reactivity and superior compared to methanol. DMC are being produced from methanol and carbon dioxide thereby making it a true green reagent. The growing interest is mainly due to its low persistence, low bioaccumulation and high biodegradability.

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Another possible way to reduce the required reaction temperature and pressure was proposed by . They developed a two-step supercritical methanol process. This process involves the hydrolysis of oil in subcritical water to producing free s and then followed by the esterification of s with supercritical methanol to produce methyl esters (biodiesel). In this method, oils/fats are, first, treated in subcritical water for hydrolysis reaction to produce s. After hydrolysis, the reaction mixture is separated into oil phase and water phase by decantation. The oil phase (upper portion) is mainly s while the water phase (lower portion) contains glycerol in water. The separated oil phase is then mixed with methanol and treated at supercritical condition to produce methyl esters thorough esterification. Another advantage of the two-step process is that a lower ratio of alcohol to oil is required. Under milder conditions, at 563 K (270°C) and 20 MPa, 90% methyl ester yield was obtained in 15 min via esterification of oleic acid (5:1 methanol to oil molar ratio) with supercritical methanol (). Since less excess methanol is necessary in this two-step process, resulting in reducing the energy consumption for recovery of unreacted methanol. The biodiesel produced from this alternate two-step method is cleaner than that from the transesterification of triglyceride alone. No mono- or diglycerides or glycerol appear as by products from the ester formation step since these compounds will have been removed after the first reaction stage (). The amount of glycerol in biodiesel phase can be reduced dramatically. The total glycerol content of biodiesel prepared by one-step and two-step supercritical processes were 0.39 and 0.15 wt%, respectively ().

Brønsted-Lewis acidic ionic liquid for the “one-pot” synthesis of biodiesel from waste oil
24/06/2017 · The application of calcined natural dolomitic rock as a solid base catalyst in triglyceride transesterification for biodiesel synthesis

Synthesis of biodiesel without formation of free …

Up to now, non-catalytic biodiesel conversion methods have been limited to the use of supercritical conditions (i.e., temperatures above 250°C and pressures above 10 MPa) (; ). Both ethanol and, especially, methanol, have been reported as supercritical fluids for biodiesel synthesis, although other fluids in supercritical conditions (e.g., dimethyl carbonate, methyl acetate) have also been evaluated (). In spite of the numerous advantages, the operational and equipment costs for producing biodiesel under supercritical conditions are huge obstacles. Another issue that must be addressed is the of biodiesel prepared by non-catalytic SCFs methods. It was found that although all methyl esters, including the poly-unsaturated ones, are stable at low temperatures and pressures but they partially decomposed with isomerization from cis-olefin to trans-olefin at high pressure and temperature. It was suggested that, for high-quality biodiesel production, the reaction temperatures in SCFs processes should be maintained below 300°C, for supercritical methanol and lower than 360°C for supercritical methyl acetate with a supercritical pressure higher than 8.09 MPa ().

(602ai) A Comparative Study of Biodiesel Synthesis From Soybean Oil Via Transesterification Reaction Using Calcium Methoxide in the Absence and Presence of …

Segredos da Produção de Biodiesel em Passos Simples… Veja!

It has also low toxicity, absent of any irritant or mutagenic effects. The economic value of by-products such as glycerol carbonate and glycerol dicarbonate, from the non-catalytic transesterification using DMC as a methyl donor, is higher than that of glycerol ().

Several methods that have been proposed for the synthesis of biodiesel from the analyzed by-products using ..

The overal result (based on theory) is cracking of the triglyceride.

Lipases (triacylglycerol acylhydrolases, EC constitute a diverse and ubiquitous family of enzymes which are produced by animals, plants and microorganisms. Lipases from microorganisms (bacterial and fungal) are the most used as biocatalysts in biotechnological applications and organic chemistry. Lipases have been successfully used in novel biotechnological applications for the synthesis of biopolymers and the production of enantiopure pharmaceuticals, flavor compounds, agrochemicals and biodiesel (). Lipases are considered hydrolases which naturally hydrolyses triacylglycerol (). Most lipases are capable of converting triglycerides, diglycerides, monoglycerides and free s to Fatty Acid Alkyl Esters in addition to fat hydrolysis (). It is the stability of lipases that allows them to catalyze the unnatural reaction of transesterification (). The advantages of using lipases in biodiesel production are: (a) Ability to work in very different media which include biphasic systems, monophasic system (in the presence of hydrophilic or hydrophobic solvents), (b) They are robust and versatile enzymes that can be produce in bulk because of their extracellular nature, (c) Many lipases show considerable activity to catalyze transesterification with long or branched chain alcohols which can hardly be converted to esters in the presence of conventional alkaline catalysts, (d) Ability to esterify both FFA and triglycerides in one step without the need of washing step; no soap formation and the ability to handle large variation in raw material quality such as waste cooking oil, (e) Products and byproduct separation in downstream process are extremely easier, (f) The immobilization of lipases on a carrier has facilitated the repeated use of enzymes after removal from the reaction mixture and when the lipase is in a packed bed reactor, no separation is necessary after transesterification, (g) Lipases have higher thermostability and short-chain alcohol-tolerant capabilities; hence making them very convenient for use in biodiesel production (; ; ; ; ). However, enzymatic transesterification has several drawbacks: (a) Longer reaction time, (b) Higher catalyst concentration is required to completion of reaction, (c) High cost of production (due to high enzyme cost- lipase enzyme makes up 90% of the total cost of enzymatic biodiesel production), (d) The risk that glycerol inhibits the lipase by covering it, due to its accumulation, (e) Initial activity may be lost because of volume of the oil molecule, (f) Although, repeated use of lipase becomes possible after immobilization of lipase on carrier, it loses its activity in 100 days of application (; ; ; ). The stability of the lipase is the most important enzymatic characteristics when used in biodiesel synthesis. The environment in a reactor is often more harsh for the enzyme than when in vivo. Therefore, many enzymes do not remain stable when used industrially. The higher temperature, inactivating impurities and aggressive surfaces of the reactors assist in enzyme deactivation and inhibition. In addition to mechanical forces, lower chain alcohols, the by-product glycerol, water content and high alcohol to oil ratios can also cause destabilization and deactivation of the enzyme (; ; ; ). Therefore, more research is needed in order to be able to use modified lipase on a large scale.