Biodiesel production additives

It is predicted that eventually biodiesel may reach 5-7% market share in Europe for diesel fuels [1.29]. This estimate is based on current and planned construction of biodiesel production facilities. When all these facilities are in place, it is estimated that over 1 million tons of biodiesel will be produced in the European Union, with 40,000 additional tons in the Czech Republic. 

Figure 9 shows a schematic process of biodiesel production by the two-step supercritical methanol method. Several advantages have been attributed to the two-step reaction method. At temperature of 270°C, a common type of 316 stainless steel can fulfill the requirements of good corrosion resistance and cover the reaction condition (5). Energy requirements may be less because mild reaction conditions for hydrolysis and methyl esterification are employed, whereas high-temperature treatment causes operational and equipment problems with, in some cases, the formation of undesirable degradation products. In addition, a reaction temperature of 270°C is commonly used in industries, so such a reaction condition is applicable for commercial applications. 

The new applications are to be found outside the traditional commercial applications of glycerol in food additives, pharmaceuticals, cosmetics and personal care products and also various industrial applications, such as the synthesis of polyethers, polyols and alkyd resins, detergents, explosives, etc. [85]. The use of low-quality glycerol from biodiesel production for these applications is often avoided, however. Additional fields of applications as a C3 building block have been widely investigated and in a few cases even commercialized, e.g. the production of epichlorohydrin via the EPICEROL process of Solvay Chemicals. 

Thus biodiesel is a better lubricity enhancer than its parent vegetable oil because of the presence of high-lubricity species, some of which, such as monoacylglycerols, can arise during biodiesel production. Biodiesel is required at levels such as 2% for lubricity enhancement in order to achieve a sufficient additive level of high-lubricity materials in petrodiesel. Table 1.17 gives data showing the effect of minor components of biodiesel on its lubricity. 

A comparative study of biodiesel production with WDO-2 using three-step methanolysis and one-step transesterification with methyl acetate was also conducted here. As can be seen in Figure 5, the ME yield of the three-step methanolysis after reaction for 72 h was 69.1%, which was much lower than those of the one-step transesterification with or without addition of organic base depicted in Figure 4, suggesting that the enzymatic transesterification with methyl acetate was more effective than the enzymatic methanolysis in solvent free system for biodiesel production. 

Currently, 58 biodiesel plants operate in the United States with a total capacity to produce 1.3 million tons of fuel and an average capacity per plant of 22 thousand metric tons (Fig. 5.33). An additional 53 plants are planned for construction with a total capacity of 2.4 million tons and an average size of 45 thousand tons. The industry is young and highly fragmented as 80% of the production is produced by 33% of the firms (Fig. 5.34). Soybeans would feed about 47% of the planned biodiesel production. The 940 thousand metric tons of additional oil demand would still only equal 10% of the 2005 U.S. oil supply, up from the current 3%. So the direct price effects from U.S. biodiesel expansion would be moderate. Most of the price effects on food oils will come from much more rapid expansion of biodiesel utilization in Europe and Asia. 

The primary soybean oil quality issues for biodiesel production are free fatty acids, moisture, and phosphorus. These correspond well to the requirements for edible oil but bleaching and deodorization are generally not required for biodiesel. It is desirable to have levels of free fatty acid and moisture as low as possible. If both contaminants are <0.1%, there will be no effect on the biodiesel process (Van Gerpen, 2005). In fact, levels of free fatty acids and moisture of 0.5%, as is common for crude as-pressed oil, can be used directly for biodiesel production. However, there will be some additional soap formation during processing that will need to be removed. 

Glycerol is a by-product in the esterification of TAGs for biodiesel production comprising 10 wt% of the overall product stream. This by-product has substantial volume, with 1.3 billion gallons of biodiesel produced in the United States in 2013 [196]. Additionally, crude glycerol has decreased in price from 0.25 to 0.05 per pound [197]. Use of glycerol for production of many compounds has been demonstrated in E. coli. 

The worldwide consumption of soybean oil was 37.9 million tons in 2008, accounting for 28% of global vegetable oil usage [1]. It finds its way into several food appHcations such as cooking oils, salad oils, or margarines. Technical uses include additives for coatings. In the biofuels industries of the United States and Brazil, soybean oil is also the main feedstock for biodiesel production (almost 20% of soybean oil went into biodiesel in the United States in 2008 [7]). 

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