Ethanol production of

A more abundantiy produced substance is ethanol for use in alcohoHc beverages, and as a fuel, solvent, and feedstock for organic syntheses. Ethanol (qv) production from sucrose is carried out in Europe (eg, France and the Netherlands), India, Pakistan, China, and on a very large scale in Brazil, where it is used as a motor fuel. A valuable by-product of ethanol fermentation is industrial CO2 (see Carbon dioxide). 

Bakers Yeast Production. Bakers yeast is grown aerobicaHy in fed-batch fermentors under conditions of carbohydrate limitation. This maximizes the yield of yeast biomass and minimizes the production of ethanol. Yeasts grown under these conditions have exceUent dough leavening capabHity and perform much better in the bakery than yeast grown under anaerobic conditions. 

Cooking extmders have been studied for the Uquefaction of starch, but the high temperature inactivation of the enzymes in the extmder demands doses 5—10 times higher than under conditions in a jet cooker (69). Eor example, continuous nonpressure cooking of wheat for the production of ethanol is carried out at 85°C in two continuous stirred tank reactors (CSTR) connected in series plug-fiow tube reactors may be included if only one CSTR is used (70). 

A. MoeUgaard and co-workers, "Continuous Low-Temperature Cooking of Wheat for Production of Ethanol," paper presented at the 7th... 

Ca.ta.lysts, At ambient temperatures, only a relatively small amount of ethanol is present in the vapor-phase equiUbrium mixture, and an increase ia temperature serves only to decrease the alcohol concentration. An increase in pressure helps to shift the equiUbrium toward the production of ethanol because of a decrease in the number of molecules (Le ChateUer s principle). On the other hand, reaction velocity is low at low temperatures. Hence it is necessary to use catalysts and relatively high temperatures (250—300°C) to approach equiUbrium within a reasonably short time. 

Eijuilibrium Constant. At the pressures used in commercial production of ethanol (6.1—7.1 MPa or 60—70 atm), alcohol yield per pass is significantly limited by equiHbrium considerations. This fact has focused attention on deterrnination of equiHbrium constants and equiHbrium yields (122—124). The results of these deterrninations are as follows ... 

Synthesis Ga.s, Since petroleum prices rose abmpdy in 1974, the production of ethanol from synthesis gas, a mixture of carbon monoxide and hydrogen, has received considerable attention. The use of synthesis gas as a base raw material has the same drawback as fermentation technology low yields limited by stoichiometry. 

Ethyl Ether. Most ethyl ether is obtained as a by-product of ethanol synthesis via the direct hydration of ethylene. The procedure used for production of diethyl ether [60-29-7] from ethanol and sulfuric acid is essentially the same as that first described in 1809 (340). The chemical reactions involved in the production of ethyl ether by the indirect ethanol-from-ethylene process are like those for the production of ether from ethanol using sulfuric acid. 

Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilised cell reactor (ICR), was successfully carried out to improve the performance of the... 

Owing to diminishing fossil fuel reserves, alternative energy sources need to be renewable, sustainable, efficient, cost-effective, convenient and safe.1 In recent decades, microbial production of ethanol has been considered as an alternative fuel for the future because fossil fuels are depleting. Several microorganisms, including Clostridium sp. and yeast, the well-known ethanol producers Saccharomyces cerevisiae and Zymomonas mobilis, are suitable candidates to produce ethanol.2,3... 

Use of biofilm reactors for ethanol production has been investigated to improve the economics and performance of fermentation processes.8 Immobilisation of microbial cells for fermentation has been developed to eliminate inhibition caused by high concentrations of substrate and product, also to enhance productivity and yield of ethanol. Recent work on ethanol production in an immobilised cell reactor (ICR) showed that production of ethanol using Zymomonas mobilis was doubled.9 The immobilised recombinant Z. mobilis was also successfully used with high concentrations of sugar (12%-15%).10... 

Fig. 8.6. Glucose concentration, cell density and production of ethanol in batch fermentation with initial concentration of 50 g-l 1 glucose versus time. Reprinted from Najafpour et al. (2004).18 Copyright with permission from Elsevier.

Kemppainen and Shonnard compared the production of ethanol via fermentation-based processes starting with two lignoceUulosic feedstocks virgin timber resources or recycled newsprint from an luban area. For this piupose, they coupled a software-aided simulation of the fermentation process with impact assessment software. 

It is well established that the main products of ethanol electro-oxidation on Pt in acidic media are acetaldehyde and acetic acid, partial oxidation products that do not require C—C bond breaking, with their relative yields depending on the experimental conditions [Iwasita and Pastor, 1994]. Apart from the loss of efficiency associated with the partial oxidation, acetic acid is also unwanted, as it constitutes a catalyst poison. 

In the production of ethanol by the hydrolysis of ethylene, diethyl ether is produced as a by-product. A typical feed stream composition is 55 per cent ethylene, 5 per cent inerts, 40 per cent water and product stream 52.26 per cent ethylene, 5.49 per cent ethanol, 0.16 per cent ether, 36.81 per cent water, 5.28 per cent inerts. Calculate the yield of ethanol and ether based on ethylene. 

Samejima, H., Nagashima, M., Azuma, M., Noguchi, S., and Inuzuka, K., Semicommercial Production of Ethanol using Immobilized Microbial Cells, Annals New York Academy of Sciences, 434 394 (1984)... 

Webb, O. F., Davison, B. H., Scott, T. C., and Scott, C. D., Design and Demonstration of an Immobilized-Cell Fluidized-Bed Reactor for the Efficient Production of Ethanol, Appl. Biochem. Biotechnol., 51/52 559 (1995)... 

Give an equation in each case for the industrial production of ethanol. 

An example is the production of ethanol by the addition of water to ethylene. 

When agricultural surplus was used for the production of ethanol in the United States, it provided economic benefits to farmers and to the farming economy. In 1990, almost 360 million bushels of surplus grain were used to produce ethanol. In that year, it is estimated that ethanol production increased farm income by 750 million while federal farm program costs dropped by 600 million and crude oil imports fell by over forty million barrels. 

By 2007, about 4% of all the fuel sold or dispensed to U.S. motorists came from renewable sources, which is almost 5 billion gallons of renewable fuels. New and expanded plants now under construction are expected to push the annual production of ethanol well above this level. 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

Table 7.16. Input and output data for the production of ethanol from wheat (Kaltschmitt and Hartmann, 2001 Punter et al., 2004)...

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