RU2043780C1 - Method for rectification of ethyl alcohol - Google Patents

Abstract

FIELD: alcohol industry. SUBSTANCE: ethyl alcohol is subjected to epuration on an epuration column and rectification on an alcohol column in presence of alkali and with joint supply into the alcohol column of potassium manganate in the amount of 0.2-0.9 g/decaliter of alcohol, and hydrogen peroxide in the amount of 0.1-0.5 g/decaliter of alcohol in terms of 100-% hydrogen peroxide. EFFECT: higher efficiency.

Description

 The invention relates to the alcohol industry, in particular to the development of methods for the purification of ethyl alcohol in the process of rectification to obtain a high-quality commercial product.

A known method of producing ethyl alcohol, including the distillation of alcohol mash into alcohol condensate, which in the form of a 20-30% solution enters the epilation column and then to the alcohol, where it is brought to a strength of 94-95 vol. Purification from acids, unsaturated and sulfur compounds is carried out in an alcohol column using sodium hydroxide, which is supplied in the form of a 5-10% aqueous solution, which corresponds to 0.1 kg of NaOH per 1 decalit [1]
As a result of the method, technical alcohol is obtained with the following characteristics: unsaturated compounds 2-10 mg / dm ³ , sulfur-containing compounds 0.1-5.0 mg / dm ³ . There is also known a method for the production of alcohol contaminated with alcohol impurities, namely, that the epurate is boiled in a digested column in the presence of alkali (up to 1 g of NaOH per 1 dm ^{3 of} alcohol), added to break down or bind esters, acids, aldehydes, sulfur compounds and amines . In the strengthening column, impurities are cleaned with potassium permanganate (0.5-0.8 g per 1 dm ^{3 of} alcohol). As a result of the reaction, non-volatile products are removed with Luther, and volatile products are removed with alcohol vapors in a strengthening column. Commercial alcohol is characterized by the following indicators: aldehydes 3 mg / dm ³ , esters 26 mg / dm ³ , free acids 15 mg / dm ³ , alkali in terms of NaoH 0.1 mg / dm ³ , oxidation 18 minutes.

A known method for the purification of synthetic alcohol [4] in a distillation unit, consisting of distillation, epuration, ether, alcohol and methanol columns, and the distillation of the epureate is carried out in an alcohol column in order to strengthen the alcohol and free propyl, butyl, amyl alcohols from high boiling impurities. An alkali solution in an amount of 3-4.5 g / dal for saponification of esters is fed into an alcohol column on a 35 plate. A solution of potassium permanganate is served on a 32 plate in an amount of 1-2 g / dal, where aldehydes and unsaturated compounds are oxidized in a slightly alkaline environment. Manganese oxide is removed in the fuselage emulsion selection zone. After the alcohol column, alcohol enters the methanol column to remove methanol, esters and aldehydes. Commercial alcohol is taken from the bottom of the column. The latter is characterized by the following indicators: aldehydes 2-40 mg / dm ³ , free acids 10-15 kg. dm ³ , esters 20-30 mg / dm ³ , unsaturated compounds 0.1-10 mg / dm ³ , dry residue 1-2 mg / dm ³ , alkali in terms of NaOH 1.0 mg / dm ³ , crotonaldehyde 0.002 about. (2.03 mg / dm ³ ), oxidation 5-20 min.

The objective of the invention is to develop a method for the purification of ethyl alcohol in a distillation unit, characterized by high quality indicators of a commercial product. The problem is solved as follows. At the stage of strengthening the alcohol in the alcohol column, alcohol is purified in the presence of hydrogen peroxide, which is supplied in an amount of 0.1-0.5 g per 1 dal of alcohol (in terms of 100% H ₂ O ₂ ) in the form of a 30-10% aqueous solution simultaneously with potassium permanganate taken in an amount of 0.2-0.9 g / dal of alcohol. The alkali solution is also served in an alcohol column in an amount of 3-4.5 g / dal of alcohol from 32-41 plates.

The novelty of the developed method for purifying alcohol consists in the use of hydrogen peroxide together with potassium permanganate in an alcohol column, as well as in the quantitative ratio between the ingredients supplied for purification, namely alkali, potassium permanganate and hydrogen peroxide. It is known from the literature that hydrogen peroxide is used to purify alcohol, which is fed to a food plate or 6 plates higher in an epilation column in an amount of 1.5% or 3.0% aqueous solution [3] This method allows to reduce the content of sulfur compounds from 0.11 to 0.05-0.7 mg / dal of alcohol. The main difference of this method is the complete removal of unsaturated compounds, which is achieved due to redox reactions that occur in the alcohol column when the combined supply of KM _n O ₄ and N ₂ O ₂ .

H

H

O

Такое расщепление происходит не только с α_т β ненасыщенными кислотами (альдегидами), но и почти с любой ненасыщенной кислотой. Для α_т β ненасыщенного полимера происходит расщепление. Точный механизм данной реакции сложен, однако его можно представить как комбинацию реакций, обратной альдегидной конденсации с биомолекулярной окислительно-восстановительной реакцией, т.о. КМ_нО₄ сильный окислитель в щелочной среде
MnO₄+ 2H₂O + 3e __→ MnO₂ + 4OH а перекись водорода в присутствии диоксида марганца MnO₂ может отдавать свой водород, выделяя при этом кислород, также необходимый для протекания реакции. Следовательно, в данном случае перекись может вести себя как восстановитель, т.е. создаются все условия для протекания окислительно-восстановительных реакций. Таким образом, изобретение отвечает критериям "Новизна" и "Изобретательский уровень". Уменьшение количества перекиси водорода совместно с марганцевокислым калием менее 0,1 г приведет к недостаточной степени окисления непредельных соединений, а увеличение количества перекиси водорода вызовет неоправданный перерасход вводимых ингредиентов без улучшения качества товарного продукта.The mechanism of this reaction can be represented:

H

H

O

This cleavage occurs not only with α _t β unsaturated acids (aldehydes), but also with almost any unsaturated acid. For α _t β unsaturated polymer cleavage occurs. The exact mechanism of this reaction is complex, but it can be represented as a combination of reactions, reverse aldehyde condensation with a biomolecular redox reaction, i.e. KM _n O ₄ strong oxidizing agent in an alkaline environment
MnO ₄ + 2H ₂ O + 3e __ → MnO ₂ + 4OH and hydrogen peroxide, in the presence of manganese dioxide, MnO ₂ can give off its hydrogen, releasing oxygen, which is also necessary for the reaction. Therefore, in this case, peroxide can behave as a reducing agent, i.e. all conditions are created for the occurrence of redox reactions. Thus, the invention meets the criteria of "Novelty" and "Inventive step". A decrease in the amount of hydrogen peroxide together with potassium permanganate less than 0.1 g will lead to an insufficient degree of oxidation of unsaturated compounds, and an increase in the amount of hydrogen peroxide will cause an unjustified overspending of the introduced ingredients without improving the quality of the commercial product.

 PRI me R 1. The synthetic alcohol of their epilation column in the form of an epuret with an alcohol content of 25% enters the alcohol column (71 plates) to strengthen the alcohol and free it from high boiling impurities. From plates 17-23 selected fusel emulsion, fusel oil from 5-11 plates. From the upper plates 60-69, fortified alcohol with a strength of 96.5 vol. and alcohol vapors, condense in reflux condensers and return to the upper plate of the alcohol column.

A solution of alkali in an amount of 3 g / dal of alcohol is supplied to a 32 plate alcohol column and a solution of potassium permanganate in an amount of 0.2 g / dal alcohol to a 35 plate together with a 10% aqueous hydrogen peroxide solution. The amount of hydrogen peroxide is 0.5 g per 1 dal of alcohol (in terms of 100% H ₂ O ₂ ). An alcohol-free luther is taken from the bottom of the column and sent to treatment facilities. From the alcohol column, alcohol enters the methanol column to remove volatile compounds (methanol, ethers, aldehydes). Commodity alcohol with a strength of 96.5 vol. during epure mode. Vapors of alcohol are condensed in the reflux condensers of the methanol column and, in the form of reflux, are returned to the methanol column. The ether-aldehyde fraction is sent to an ether column.

Commodity alcohol is characterized by the following indicators:
ethanol content 96.5%
the concentration of acids in terms of acetic acid is 8 mg / dm ³ , aldehydes of at least 30 mg / dm ³ , esters of 20 mg / dm ³ . fusel oils 30 mg / dm ³ , acetic aldehyde is absent, crotonaldehyde is absent, solids concentration is 1 mg / dm ³ .

PRI me R 2. Diffuse condensates obtained as a result of processing sulfite mash, sent after the epilation column to the alcohol column. The alcohol content in the plot is 15%. Next, analogously to example 1, an alkali solution of 4.5 g / dal of alcohol for 41 plates is supplied, a solution of potassium permanganate 0.9 g / dal is fed to 39 plates, a solution of hydrogen peroxide 0.1 g / dal of alcohol in the form A 20% solution is served together with potassium permanganate on a 39 plate. Next, the alcohol is sent to a methanol column and a commercial product taken from the cube of the methanol column is characterized by the following indicators: ethyl alcohol content 96.5% esters 12 mg / dm ³ , acids in terms of acetic acid 9 mg / dm ³ , no unsaturated compounds, dry residue less than 0.1 mg / DM ³ .

 As can be seen from the above examples, the developed method allows to provide high quality commercial product.

Claims (1)

 METHOD FOR CLEANING ETHYL ALCOHOL, including epuring it on an epilation column and rectification on an alcohol column in the presence of alkali and potassium permanganate, characterized in that potassium permanganate is supplied to the alcohol column in an amount of 0.2 0.9 g / dal of alcohol together with hydrogen peroxide, taken in an amount of 0.1 to 0.5 g / dal of alcohol in terms of 100% hydrogen peroxide.