Biodiesel fuels transesterification process

Starch and fatty acids are the main food constituents of biomass. Sugar is derived from starch by hydrolysis or directly by extraction from sugar cane or beet. Fermentation converts sugars into alcohol that can be directly used as fuel, or in principle can be used as the raw material of a bioreftnery plant for further upgrading. Triglycerides, derived from oil seeds, are used to be converted into biodiesel through transesterification processes (Fig. 1.14). 

Current biodiesel can not be considered as a 100% biomass-based fuel as long as methanol is derived from petrochemical resources. A clean way to solve the biorelated problem is the conversion of glycerol waste from the transesterification process into syngas. In this context, glycerol reforming is a suitable target reaction worthy of study. 

Fatty acid methyl esters (FAMEs) show large potential applications as diesel substitutes, also known as biodiesel fuel. Biodiesel fuel as renewable energy is an alternative that can reduce energy dependence on petroleum as well as air pollution. Several processes for the production of biodiesel fuel have been developed. Transesterification processes under alkali catalysis with short-chain alcohols give high yields of methyl esters in short reaction times. We investigated transesterification of rapeseed oil to produce the FAMEs. Experimental reaction conditions were molar ratio of oil to alcohol, concentration of catalyst, type of catalyst, reaction time, and temperature. The conversion ratio of rapeseed oil was enhanced by the alcohohoil mixing ratio and the reaction temperature. 

Several processes for the production of biodiesel fuel have been developed by acid-, alkali-, and enzyme-catalyzed transesterification reactions (7-10). Transesterification, called alcoholysis, is the displacement of alcohol from an ester by another alcohol in a process similar to hydrolysis. Transesterification is represented by a number of consecutive and reversible reactions. The reaction step is the conversion of triglycerides to diglycerides, followed by the conversion of diglycerides to monoglycerides and of monoglycerides to glyceride at each step (11,12). 

Base-catalyzed transesterification is the process that converts waste cooking oil to biodiesel fuel. 

A biodiesel or alkyl ester fuel engine can be used within a hybrid system or alone. Biodiesel is a clean-burning alternative to diesel or petroleum. It is produced from fats or oils through transesterilication. Biodiesel must be produced through ASTM D6751 in order to ensure its performance [13]. Biodiesel produced in this manner can be used with little modification to its structure. Sulfur or aromatics are not present in its structure. The transesterification process used to produce the fuel is shown in Figure 12.2. 

Abstract Biodiesel is a fatly acid alkyl ester that can be derived fiom any v etable oil or animal fat via the process of transesterification. It is a renewable, biodegradable, and nontoxic fuel. In this paper, we have evaluated the efficacy of a transesterification process for rapeseed oil with methanol in the presence of an enzyme and tert-butanol, which is added to ameliorate the negative effects associated with excess methanol. The application of Novozym 435 was determined to catalyze the tiansesterification process, and a conversion of 76.1% was achieved under selected conditions (reaction temperature 40 °C, methanol/oil molar ratio 3 1, 5% (w/w) Novozym 435 based on the oil weight, water content 1% (w/w), and reaction time of 24h). It has also been determined that rapeseed oil can be converted to fatty acid methyl ester using this system, and the results of this study contribute to the body of basic data relevant to the development of continuous enzymatic processes. 

Various solid and liquid renewable sources have also been proposed for producing syngas for MCFCs wood [61, 62], chestnut coppice [63], bioethanol [17,19, 20], and the glycerol obtained as a by-product in biodiesel production with the transesterification process [16]. Oxygenated liquid fuels are challenging for the reforming step (see Section 3.1.4). 

Various biodiesel blends, which include different ratios of biodiesel and diesel from crude oil, can be used in vehicles depending upon the vehicle s requirement and weather conditions. A 20% biodiesel will provide a higher octane rating, superior lubricity, significant emission reductions, and less toxic emissions will virtually eliminate visible soot emissions and will have similar fuel consumption, horsepower, and torque. Premium biodiesel is a fuel manufactured from vegetable oils by a transesterification process. Soybean oil is currently the leading source of vegetable oil for biodiesel manufacture in the United States. 

Biodiesel (FAME) is a renewable fuel that is made by transesterification of vegetable oils or animal fat with methanol. Several different types of oils could be used, the most common are soybean oil, rapeseed oil, and palm oil [66]. The most widely used transesterification process for commercial biodiesel is alkali-catalyzed [67]. This process typically uses NaOH or KOH as a catalyst. Although the biodiesel is purified, residual amounts of Na or K can remain in the biodiesel [68]. Current standard is Na H- K < 5 ppm for 100 % biodiesel (BlOO). Biodiesel also contains phosphorus that originates from phospholipids. The current standard is P < 4 ppm for BlOO. 

The use of methanol offers the best results in the trans-esterification of oils and fats. Compared with other alcohols, methanol requires shorter reaction times and smaller catalyst amounts and alcohol/oil molar ratios [10,12,15,16,51,52]. These advantages lead to reduced consumption of steam, heat, water, and electricity, and use of smaller processing equipment to produce the same amount of biodiesel. Biodiesel applications continue to expand. Thus, in addition to its use as fuel, biodiesel has been employed in the synthesis of resins, polymers, emulsifiers, and lubricants [53-64]. Concerning the range of applications, new biodiesel production processes should be considered as alternatives to the production based on methanol. Currently, methanol is primarily produced from fossil matter. Due to its high toxicity, methanol may cause cancer and blindness in humans, if they are overexposed to it. Methanol traces are not desired in food and other products for human consumption [15]. In contrast, ethanol emerges as an excellent alternative to methanol as it is mainly produced from biomass, is easily metabolized by humans, and generates stable fatty acid esters. Additionally, fatty acid ester production with ethanol requires shorter reaction times and smaller amounts of alcohol and catalyst compared to the other alcohols, except methanol, used in transesterification processes [11,15,16]. 

Starting point for the analysis of the different stages of the biodiesel life cycle is again the transesterification process with its inputs, process energy and process chemicals. The other two stages of the life cycle are classified as transport, considering both collection of the raw material and fuel delivery, and the combustion of biodiesel (see Table III). 

Georgogianni, K.G., Kontominas, M.G., et al., 2008. Conventional and in situ transesterification of sunflower seed oil for the production of biodiesel. Fuel Processing Technology 89 (5), 503-509. 

Sinha, S., Agarwal, A.K., Garg, S., 2008. Biodiesel development from rice bran oil transesterification process optimization and fuel characterization. Energy Conversion and Management 49, 1248—1257. 

Biomass is a renewable resource from which various useful chemicals and fuels can be produced. Glycerol, obtained as a co-product of the transesterification of vegetable oils to produce biodiesel, is a potential building block to be processed in biorefineries (1,2). Attention has been recently paid to the conversion of glycerol to chemicals, such as propanediols (3, 4), acrolein (5, 6), or glyceric acid (7, 8). 

Biodiesel is a mixture of methyl esters of fatty acids and is produced from vegetable oils by transesterification with methanol (Fig. 10.1). For every three moles of methyl esters one mole of glycerol is produced as a by-product, which is roughly 10 wt.% of the total product. Transesterification is usually catalyzed with base catalysts but there are also processes with acid catalysts. The base catalysts are the hydroxides and alkoxides of alkaline and alkaline earth metals. The acid catalysts are hydrochloride, sulfuric or sulfonic acid. Some metal-based catalysts can also be exploited, such as titanium alcoholates or oxides of tin, magnesium and zinc. All these catalyst acts as homogeneous catalysts and need to be removed from the product [16, 17]. The advantages of biodiesel as fuel are transportability, heat content (80% of diesel fuel), ready availability and renewability. The... 

Meher, L.C., Vidya Sagar, D., Naik, S.N., Technical aspects of biodiesel production by transesterification, Renew. Sustain. Energy Rev., 10, 248-268, 2006 Minami, E., Saka, S., Kinetics of hydrolysis and methyl esterification for biodiesel production in two-step supercritical methanol process. Fuel, 85, 2479-2483, 2006... 

Finally, multi-process units are being built that can deal with both alkaline and acid transesterification. Such biodiesel producers are well positioned to develop an expanding supply of fuel based on both recycled and virgin vegetable oils. 

Esterfip-H A process for converting vegetable oils to methyl esters for use as diesel fuel ( biodiesel ). A heterogeneous transesterification catalyst is used. Developed by IFP and Sofiproteol, France licensed by Axens. Proposed for operation in Sete, France, in 2006, and by Perstorp Oxo in Stenungsund, Sweden, in 2007. 

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