Purification of ethanol pdf

Click here to sign up. Download Free PDF. Himanshu C. A short summary of this paper. Download Download PDF. Translate PDF. This is possible because the new processes use less energy in recovering the alcohol than does the traditional method of distillation.

Hence, main objective is lowering the cost of alcohol and get purify ethanol as much as possible. By solubility difference, alcohol can be recovered from aqueous solutions by solvent extraction. Another approach is to use membranes that are permeable to alcohol but not water. This has traditionally been accomplished by Azeotropic or extractive distillation, but the high-energy costs of these processes have stimulated a search for a more efficient method of separation.

Removal of moisture by adsorption on Zeolite-3Ao is a promising alternative to the conventional processes. The Zeolite-3Ao has the advantage that the micro pores are too small to be penetrated by alcohol molecules so the water is adsorbed without competition from the liquid phase. Many new crystalline Zeolites have been property to loose water on heating dates back to the synthesized and several fulfill important functions in Swedish mineralogist, Baron Cronstedt in In the chemical and petroleum industries and consume , J.

McBain first spoke of Zeolite as products such as detergents [3]. The adsorption operation exploits the ability of certain solids preferentially to concentrate specific substances from solution onto their surfaces [1].

In extruded pellets and in the form of beads or spheres. Size up to 6mm is common. Much of the recent interest is in the use of ethanol as fuel.

In this paper, we have reviewed published literature on current ethanol production and separation methods, and chemical and sensory analysis techniques.

It is recently widely used as an additive to gasoline. Corn in the Unites States and sugarcane in Brazil are widely used as raw materials to produce bioethanol.

Cellulosic materials are expected to be the ultimate major source of ethanol and also represent a value-adding technology for agricultural coproducts. While bioethanol is considered as a sustainable energy source, it requires further purification for uses other than fuel.

The most common purification technique utilized in the ethanol industry is rectification by further distillation. However, distillation has critical disadvantages including high cost and limited separation capacity. Several alternatives have been proposed to replace distillation such as non-heating fractional distillation by ultrasonic irradiation, oxidation of impurities by ozone, and adsorption of impurities by activated carbon or zeolite.

Benzene, ethanol, and water form a ternary azeotrope with a boiling point of Since this azeotrope is more volatile than the ethanol-water azeotrope, it can be fractionally distilled out of the ethanol-water mixture, extracting essentially all of the water in the process.

The bottoms from such a distillation is anhydrous ethanol, with several parts per million residual benzene. Benzene is toxic to humans, and cyclohexane has largely supplanted benzene in its role as the entrainer in this process. However, this purification method leaves chemical residues which render the alcohol unfit for human consumption.

Alternatively, a molecular sieve can be used to selectively absorb the water from the Synthetic zeolite in pellet form can be used, as well as a variety of plant-derived absorbents, including cornmeal, straw , and sawdust.

The zeolite bed can be regenerated essentially an unlimited number of times by drying it with a blast of hot carbon dioxide. Cornmeal and other plant-derived absorbents cannot readily be regenerated, but where ethanol is made from grain, they are often available at low cost.

Absolute ethanol produced this way has no residual benzene, and can be used to fortify port and sherry in traditional winery operations.

Membranes can also be used to separate ethanol and water. The membrane can break the water-ethanol azeotrope because separation is not based on vapor-liquid equilibria. Membranes are often used in the so-called hybrid membrane distillation process. This process uses a pre-concentration distillation column as first separating step. The further separation is then accomplished with a membrane operated either in vapor permeation or pervaporation mode.

Vapor permeation uses a vapor membrane feed and pervaporation uses a liquid membrane feed. At pressures less than atmospheric pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures, and at pressures less than 70 torr 9.