Biodiesel

Biodiesel, which is a fatty acid methyl ester, is a good replacement for petroleum diesel, because it is renewable, biodegradable, and less toxic. Commercially, biodiesel is produced using an alkali process. This is a cost-effective and highly efficient process. However, to avoid downstream process problems, the feed must be purified and free of fatty acids. 

Biodiesel production using the biocatalyst lipase avoids the disadvantages of the alkaline process without the need for subsequent wastewater treatment (Taher et al., 2011). Additionally, lipases can operate in mild conditions with a high substrate selectivity. M. miehei, R. oryzae, C. antarctica, and P. cepacia are all common lipases found to be capable of catalyzing oil transesterification in order to produce biodiesel. 

The economics of biodiesel production can be significantly improved by employing more environmentally friendly processes during the manufacturing process. 

Biodiesel, being a high-volume product, currently results in large amounts of glycerol by-product which can be used as a feedstock for commodity chemical products, feed applications, materials, and energy. The EU-funded Sustoil [17] project has identified a number of potential applications for glycerol which could result in commercial opportunities. Some of the appUcations of glycerol are discussed later in this chapter. 

Due to the high efficiency of photosynthesis and the yields of biomass being significantly higher per area of land, many companies and investors have tried to reduce the costs and take on the above challenges head on. Some of these are shown in Table 6.1. 

ExxonMobil has invested 600 million in algae technology and this is the boldest move made by the industry so far. In partnership with Synthetic Genomics, the algae cells have been engineered to secrete the triglyceride oil. This means the oil floats on top of the culture vessels so there is no need to harvest the algae [19]. 

AlgaeVenture Systems The process can reduce the cost of dewatering by 98% compared to centrifugation. 

In particular, methyl soyate (the biodiesel formed from soybean oil and methanol) is finding industrial applications including cleaning and degreasing technologies (Table 5.5). In industry, solvents are needed to dissolve a material for its removal or transport and then are often evaporated to restore the original material. Therefore, two important parameters are solvent power and evaporation rate. One way to measure solvent power is the kauri-butanol value (KBV), which is a measure of the solubility of kauri gum in the solvent. A high 

Safety advantages Lower toxicity than toluene and methylene chloride, LD50 17.4gkg- Low vapour pressure, 0.1 mmHg High flash point, 182 °C 

Reaction and process Excellent compatibility with other organic solvents, metals 

Household cleaners, food processing equipment cleaning, asphalt handling 

With ethyl lactate, as a cleaner in the aerospace and electronics industries 

In this experiment, you will prepare biodiesel from a vegetable oil in a base-catalyzed transesterification reaction  

The first step in the mechanism for this synthesis is an acid-base reaction between sodium hydroxide and methyl alcohol  

Methoxide ion is a strong nucleophile that now attacks the three carbonyl groups in the vegetable oil molecule. In the last step, glycerol and biodiesel are produced. 

Because the R groups may have different numbers of carbons and they may be saturated (no double bonds) or may have one or two double bonds, biodiesel is a mixture of different molecules—all of which are methyl esters of fatty acids that made up the original vegetable oil. Most of the R groups have 10-18 carbons that are arranged in straight chains. 

When the reaction is complete, the mixture is cooled and then centrifuged in order to separate the layers more completely. Since some unreacted methyl alcohol will be dissolved in the biodiesel layer, this layer is heated in an open container to remove all the methyl alcohol. The remaining liquid should be pure biodiesel. 

The production of ester-based fuels such as biodiesel or jet fuel from renewable starting materials, such as lignocellulosic material or algae has been described (59). The pulping and saccharification of the renewable starting materials produces carboxylic acids, such as fatty acids or rosin acids, which are esterified via a gas sparged, slurry form of heterogeneous reactive distfllation to yield ester-based fuels. 

The process for the production of ester-based fuel from renewable starting material comprises (59)  

The isolation of cellulose and other soluble and insoluble sugars, including isolation by hydrolysis or saccharification of the comminution product 

Refining of the resulting ester to produce an ester-based fuel 

Materials destined for cellulosic ethanol production have been evaluated, and they were found to contain low relative concentrations of fatty acids. Relative to the amount of ethanol produced, the amount of fatty acid byproduct is actually quite significant. Assuming a t q)ical yield of 20% ethanol and 2% fatty acid means that a minimum of 10% of an ethanol producer s high value products could be in the form of fatty acids (59). It has been claimed that microalgal biodiesel is a better alternative than bioethanol from sugarcane (13). 

Byproducts of biofuel production are glycerin and lignin. The production of each gallon of biodiesel also produces a pound of glycerin. These materials can be used to replace oil-based products with bio-based ones. It is expected that in the decades to come, the development of the biofuel industry will result in the building of multiproduct biorefineries. 

In the past, plastics have been made from hydrocarbons. Now, with the development of new catalysts, they can also be made from agricultural products. The organic alternatives to petrochemical polymers cannot only 

Post-Oil Energy Technology After the Age of Fossil Fuels 

In many locations, the electricity generated by wind farms is already cost competitive. 

Considerable attention is currently being focused on the use of renewable vegetable oils as feedstocks for the production of biodiesel. The latter has obvious benefits in the context of green chemistry and sustainability (i) since it is plant-derived its use as a fuel is C02-neutral, (ii) it is readily biodegradable, (iii) its use results in reduced emissions of CO, SOx, soot and particulate matter. 

The reaction is catalyzed by a variety of both acids and bases but simple bases such as NaOH and KOH are generally used for the industrial production of biodiesel [200, 201]. The vegetable oil feedstock, usually soybean or rapeseed oil, needs to be free of water ( 0.05%) and fatty acids ( 0.5%) in order to avoid catalyst consumption. This presents a possible opportunity for the application of enzymatic transesterification. For example, lipases such as Candida antarctica B lipase have been shown to be effective catalysts for the methanolysis of triglycerides. When the immobilized form, Novozyme 435, was used it could be recycled 50 times without loss of activity [201, 202]. The presence of free fatty acids in the triglyceride did not affect the enzymes performance. The methanolysis of triglycerides catalyzed by Novozyme 435 has also been successfully performed in scC02 as solvent [203]. 

Alkali-catalyzed transesterifications have several drawbacks in addition to the problem of free fatty acids and water in the feedstock. They are energy intensive, recovery of the glycerol is difficult, the basic catalyst has to be removed from the product and the alkaline waste water requires treatment. These disadvantages could be circumvented by employing a lipase catalyst. But, in order to be economically viable, the enzyme costs have to be minimized through effective immobilization and recycling. 

A spin-off effect of the recent enormous increase in biodiesel production is that the coproduct, glycerol, has become a low-priced commodity chemical. Consequently, there is currently considerable interest in finding new applications of glycerol [204]. One possibility is to use glycerol as the feedstock for fermentative production of 1,3-propanediol (see earlier). 

Other options to help the environment imperative could be utilized for these types of hybrids. This includes using a pure ethanol (E100) ICE, a fuel cell, or a biodiesel fuel engine. 

The biodiesel production process has three basic routes from fats and oils to produce esters or biodiesel, according to the National BioDiesel Board [14]  

In the United States, the most utilized process is the base catalyzed transesterification of oil with alcohol. The base catalysis is popular because of its 

Production of biodiesel fuel in the United States since 1999 is shown in Table 12.3 [13] it is expected to grow in the coming years. Biodiesel has completed the health effects testing requirements of the 1990 Clean Air Act and is legally registered with the Environmental Protection Agency as a legal motor fuel for sale and distribution within the United States. 

Biodiesel is technically defined as monoalkyl esters of long chain fatty acids derived from vegetable oils or animal fats conforming to ASTM D6751 specifications [13]. Blends are denoted as BXX XX indicates the percentage of biodiesel contained within the blend. As we go forward, it is up to today s automotive chemist to work to develop efficient processes such as these in order to maintain our environment as well as to remain competitive in a global market. 

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The sources of biofuels and the methods for bioenergy production are too numerous for an exliaustive list to be described in detail here. Instead, electricity production using direct combustion, gasification, pyrolysis, and digester gas, and two transportation biofuels, ethanol and biodiesel, are discussed below. 

Biodiesel is diesel fuel produced from vegetable oils and other renewable resources. Many different types of oils can he used, including animal fats, used cooking oils, and soybean oil. Biodiesel is miscible with petroleum diesels and can he used in biodiesel-diesel blends. Most often blends are 20 percent biodiesel and 80 percent traditional diesel. Soy diesel can be used neat (100%), hut many other types of biodiesel are too viscous, especially in winter, and must be used in blends to remain fluid. The properties of the fuel will vaiy depending on the raw material used. Typical values for biodiesel are shown in Table 1. 

Biodiesel does not present any special safety concerns. Pure biodiesel or biodiesel and petroleum diesel blends have a higher flash point than conventional diesel, making them safer to store and handle. Problems can occur with biodiesels in cold weather due to their high viscosity. Biodiesel has a higher degree of unsaturation in the fuel, which can make it vulnerable to oxidation during storage. 

Production costs for biodiesel from soybean oil exceeds 2.00 per gal ( 0.53 per 1), compared to 0.55 to 0.65 per gal ( 0.15 to 0.17 per 1) for conventional diesel. The main cost in biodiesel is in the raw material. It takes about 7.7 lb (3.5 kg) of soybean oil valued at about 0.25 per lb (0.36 per kg) to make 1 gal (3.81) of biodiesel. Waste oils, valued at 1 per gal ( 3.79 per 1) or less, have the potential to provide low feedstock cost. However, much waste oil" is currently collected, reprocessed as yellow and white greases, and used for industrial purposes and as an animal feed supplement. Production of biodiesel... 

In addition to greenhouse benefits, biodiesels offer environmental advantages over conventional diesel. Biodiesels produce similar NO, emissions to conventional diesel, fuel but less particulate matter. Biodiesel is more biodegradable that conventional diesel making any spills less damaging in sensitive areas. In general biodiesel provides more lubrication to the fuel system than low-sulfur diesel. 

Target CNG Synthetic Fuel Ethanol Biodiesel Hydrogen... 

Heterogeneous catalytic deoxygenation of stearic acid for production of biodiesel. Ind. Eng. Chem. Res., 45, 5708-5715. 

The first engines invented by Rudolf Diesel ran on groundnut oil, but because of the advent of relatively cheap oil this type of biodiesel never became commercially viable. Since about 1930 the diesel engine has been refined and fine tuned to run on the diesel fraction of crude oil, which consists mainly of saturated hydrocarbons. For this reason the modem diesel engine cannot run satisfactorily on a pure vegetable oil feedstock because of problems of high viscosity, deposit formation in the injection system and poor cold-start properties. Today, however, environmental... 

It is the last two problems, particularly in urban areas, that are causing most public concern. Most recent research into biodiesel has focused on vegetable oils such as soybean, sunflower, palm and rapeseed. Although animal fats have been considered, their availability in the quantities required have precluded serious utilization. 

In order to convert the raw oils into useful material, transesterification technology is used. The oil is reacted with a low molecular weight alcohol, commonly methanol, in the presence of a catalyst to form the fatty acid ester and glycerol (Scheme 6.1). The ester is subsequently separated from the glycerol and used as biodiesel, the glycerol being used as a raw material for fine chemicals production. Although the chemistry is simple, in order to make biodiesel commercially viable the process must be... 

Biodiesel from Transesterification of Cottonseed Oil by Heterogeneous catalysis... 

The transesterification reactions were conducted in a sealed 250 ml autoclave equipped with a stirrer. The molar ratio of methanol to oil was 12 1, reaction temperature was 200 C-230°C, and the ratio of catalyst to oil was about 2 wt%. Samples were taken out from the reaction mixture and biodiesel portions were separated by centrifuge. 

The concentration of biodiesel (fetty acid methyl esters) and glycerides were analyzed by liquid chromatography (Shimadzu-lOA HPLC). An ODS-2 column (250x4.6mm) was used for the separation. The flow rate of the mobile phase (acetone acetonitrile=l l) was set to 1 ml/min. Peaks were identified by comparison with reference standards. Standards of methyl esters, monoglycerides, digjycerides and triglycerides were bought from Fluka. 

Experiments showed that high methyl ester yields can be achieved with solid bases and super acids under moderate reaction conditions. The solid bases were more effective catalysts than the solid super acids. High stability can be achieved by an ordinary inexpensive preparation process, and the catalyst can be separated easily from the reaction products in the heterogeneous catalysis process. The costly catalyst removal process can be avoided compared with the homogeneous process. Therefore, the heterogeneous process using a solid catalyst should be more economical for biodiesel production. 

Sheehan, J., Camobreco, V., Duffield, J., Graboski, M., and Shapouri, H. (1998). Life cycle inventory of biodiesel and petroleum diesel for use in an urban bus. Final Report. National Renewable Energy Laboratory, US Department of Energy. 

In our first experiment we decided to test the conversion of sunflower oil into biodiesel (16). Treatment of sunflower oil (1) with NaOMe in MeOH results in formation of a mixtme of fatty acid methyl esters (FAME), also known as biodiesel, and glycerol (2) (Figme 4.3). The reaction was performed with a six-fold molar excess of methanol with respect to sunflower oil at elevated temperatures (60°C) using a basic catalyst (NaOMe, 1% w/w with respect to sunflower oil). The CCS was equipped with a heating jacket to ensure isothermal conditions. The sunflower oil was preheated to 60°C and was pumped at 12.6 ml/min into one entrance of the CCS. Subsequently, a solution of NaOMe in MeOH was introduced through the other entrance at a flow rate of 3.1 ml per minute. After about 40 minutes, the system reaches steady state and the FAME containing some residual sunflower oil is coming... 

Figure 4.3 Continuous production of biodiesel in CCS (2 duplo runs).

Using the optimum settings, biodiesel is produced at a volumetric production rate of 61 kg biodiesel/m -min, which compares well with 42 kg/m -min reported for typical batch processes (17). In addition, the current process is much more efficient since there is no separate separation step and reactor cleaning in between batches can be omitted (18). 

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