Manufacture of ethanol

The reconcentration of dilute (50—60%) sulfuric acid is one of the more costly operations in the manufacture of ethanol by this process. An acid reboiler, followed by a two-stage vacuum evaporation system, raises acid concentration to about 90%. The 90% acid is then brought to 96—98% strength by fortification with 103% oleum (fuming sulfuric acid). 

Direct Hydration of Ethylene. Hydration of ethylene to ethanol via a Hquid-phase process cataly2ed by dilute sulfuric acid was first demonstrated more than a hundred years ago (82). In 1923, the passage of an ethylene-steam mixture over alumina at 300°C was found to give a small yield of acetaldehyde, and it was inferred that this was produced via ethanol (83). Since the late 1920s, several industrial concerns have expressed interest in producing ethanol synthetically from ethylene over soHd catalysts. However, not until 1947 was the first commercial plant for the manufacture of ethanol by catalytic hydration started in the United States by Shell the same process was commerciali2ed in the United Kingdom in 1951. 

Industrial ethanol is one of the largest-volume organic chemicals used in industrial and consumer products. The main uses for ethanol are as an intermediate in the production of other chemicals (Table 8) and as a solvent. As a solvent, ethanol is second only to water. Ethanol is a key raw material in the manufacture of dmgs, plastics, lacquers, poHshes, plasticizers, perfumes, and cosmetics. Around 1960, manufacture of ethanol was the top consumer of ethylene in the United States, but since 1965 it has rated below manufacture of ethylene oxide and polyethylene. 

A chemical reactor is an apparatus of any geometric configuration in which a chemical reaction takes place. Depending on the mode of operation, process conditions, and properties of the reaction mixture, reactors can differ from each other significantly. An apparatus for the continuous catalytic synthesis of ammonia from hydrogen and nitrogen, operated at 720 K and 300 bar is completely different from a batch fermenter for the manufacture of ethanol from starch operated at 300 K and 1 bar. The mode of operation, process conditions, and physicochemical properties of the reaction mixture will be decisive in the selection of the shape and size of the reactor. 

For biochemical reactions, the performance of the reactor will normally be dictated by laboratory results, because of the difficulty of predicting such reactions theoretically6. There are likely to be constraints on the reactor performance dictated by the biochemical processes. For example, in the manufacture of ethanol using microorganisms, as the concentration of ethanol rises, the microorganisms multiply more slowly until at a concentration of around 12% it becomes toxic to the microorganisms. 

The larger hydrocarbon molecule has been broken down into a mixture of a shorter chain alkane plus an alkene. Both of these products are useful the alkane for the manufacture of petrol and the alkene for the manufacture of ethanol, by hydration, and plastics such as (poly)ethene. 

Classical examples of industrial biotechnology include the manufacture of ethanol, lactic acid, citric acid, and glutamic acid. The share of renewables in the feedstock of the chemical industry is expected to increase substantially in the years to come [2-4], A newcomer here is propane-1,3-diol (DuPont/Tate Lyle), with the start-up of industrial fermentation foreseen within one year. 

The situation with regard to ethanol is much clearer there is long industrial experience in the manufacture of ethanol from wood, by fermentation of the sugars in the waste effluents of pulp mills, or of the sugars made by wood hydrolysis ( ). In the years following World War II, wood hydrolysis plants have been unable to compete economically with petroleum-based ethanol synthesis, mainly by hydration of ethylene, and they have been shut down in most countries. However, in the Soviet Union, we understand, there are still about 30 wood hydrolysis plants in operation (10). Many of these are used for fodder yeast production (11) but the wood sugars are also available for ethanol production. 

When alkenes react with concentrated sulfuric acid, the corresponding sulfate esters (alkyl hydrogen sulfate, dialkyl sulfate) are formed. Depending on the alkene structure and the acid concentration, ester formation is accompanied by polymer formation (see Section 13.1.1). Hydrolysis of the sulfate esters allows the synthesis of alcohols. The reaction, called indirect hydration, is applied in the manufacture of ethanol and 2-propanol (see Section 6.1.3). 

In the manufacture of ethanol, for instance, this is done in two stages at 70°C and 100°C, respectively, with added water to get a final concentration of H2S04 of about 40-50%. This technology is designed to suppress ether formation the principal side reaction. 

Another important addition reaction is the one used in the manufacture of ethanol. Ethanol has important uses as a solvent and a fuel (p. 94). It is formed when water (as steam) is added across the double bond in ethene. For this reaction to take place, the reactants have to be passed over a catalyst of phosphoric(v) acid (absorbed on silica pellets) at a temperature of 300 °C and pressure of 60 atmospheres (1 atmosphere =... 

D. M. Jenkins and T. S. Reddy, Economic Evaluation of the MIT Process for Manufacture of EthanolL)SF-3992-Tl,NsitioasiTechnicsila oini3tioa Service, Washington, D.C., 1979. 

FIGURE 11.3 Flow scheme for manufacture of ethanol from com. From Klass (1994). 

The only compound of samarium with any commercial applications is samarium oxide (Sm203). This compound is used in the manufacture of special kinds of glass, as a catalyst in the manufacture of ethanol (ethyl alcohol), and in nuclear power plants as a neutron absorber. 

Some of the properties of dextrins may be easily and effectively modified. One of them is the solubility of dextrins. The hydrolysis of dextrins in the presence of a reversed micelle has been carried out as a part of model studies on the depolymerization of polysaccharides, and of poly- as well as oligo-saccharide waste, for the manufacture of ethanol and livestock feed. It was found that dextrin may be readily hydrolyzed in benzene by means of... 

Compare the latent heat, heat of combustion, and octane number of ethanol with the values of methanol in Table 6.1. How does the price of ethanol in dollars per million Btu compare with the price of methanol What are the important methods of manufacture of ethanol Who are the five leading producers How many of these also produce methanol ... 

As a catalyst in the manufacture of ethanol (ethyl alcohol), ethylene, and other organic compounds ... 

Fio. 13-7. Flow diagram of Shell process for manufacture of ethanol. [Petroleum Refiner, 34 (12), 145 (1955), by permiseion.]... 

Large-Scale Manufacture of Ethanol-Based Proliposomes.413... 

LARGE-SCALE MANUFACTURE OF ETHANOL-BASED PROLIPOSOMES... 

Despite the efficiency of the manufacture of ethanol from petrochemical feedstocks, much of the world s production is based on a fermentation process. Over the past 75 years in the United States, where the total annual production now stands at just under 4 million tonnes, the source of this basic chemical feedstock has swung away from fermentation to petrochemistry and back again (Table 6.1). The carbon source for the fermentation is glucose derived from starch (see Section 6.6). An even larger quantity, about 9.5 million tonnes, is produced each year in Brazil from cane sugar. Nowadays the prime consumer is the motor car. 

Economic, political and social pressures have influenced the manufacture of ethanol since the fermentation process was introduced many years ago (see Chapter 1). In the nineteenth century its status as an industrial solvent was assured when industrial methylated spirit, which is ethanol denatured with methanol to make it unfit for human consumption, was freed from excise duty. In the twentieth century, the social and political pressures which provide economic support for agriculture have allowed fermentation to compete effectively with petrochemistry as a manufacturing process. The technical achievements in chemistry, biology and engineering have only facilitated the switch between carbohydrate and oil as feedstock for the process. 

Until the petrochemical and natural gas boom, industrial ethanol was manufactured primcurily by fermentation of molasses. The production of ethylene with a selling price of only 3< /lb combined with increased use of molasses in animal feed led in the United States to the manufacture of ethanol primarily by hydration of ethylene. 

A process, called indirect hydration, is applied in the manufacture of ethanol and 2-propanol. In this reaction alkenes are reacted with concentrated sulfuric... 

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