The method of dehydration of aliphatic alcohols c1-c3

 

The invention relates to a method of dehydration of aliphatic alcohols C1-C3. The method consists in the adsorption of water-alcohol mixture on zeolite adsorbent in an adsorber operating in series or in parallel, when applying the mixture on top of the adsorbers at elevated temperature and pressure in the adsorbers using a zeolite of structural type And responsible chemical formula IUandAboutAl2About3bSiO2-CH2Oh, where Me is K, Na, Ca, Mg, Ba, Sr in different ratios and combinations thereof; and=0,8-2,1, b=1,5-2,2, C=0.2 to 25. The adsorption of water-alcohol mixture is carried out at temperatures at the entrance to the adsorbers above the boiling point of water - 105-140oC. the Method allows to minimize the loss of alcohol during zeolite drying and get "a pass" deeply drained the alcohol product. 2 C.p. f-crystals, 1 tab., 1 Il.

The invention relates to the field of technology of organic substances, and in particular to methods of obtaining drained aliphatic alcohols C1-C3methanol, ethanol, n - and isopropanol.

A method of obtaining absolute ethanol /Patent GDR 283041, 1990/, preduster disc equipment when heated, normal or increased pressure. The output of absolute ethanol is 97-99% when the content of moisture of 0.1-0.5%. The main drawback of this method is the presence in the final dried ethanol agents azeotropic distillation of benzene, cyclohexane, or trichloroethylene that does not allow to consider the final product quality.

A method of obtaining absolute ethanol /Application Germany 3727171, 1989/, based on the use of the scheme distillation dehydration of ethanol digidratirovannogo l2or SrCl2. According to this method, the preliminary first column removes solid particles from the alcohol and most of the water, then alcohol-containing head wrap is directed to the second vacuum column, the upper part of which is filled CaCl2(SrCl2). As phlegmy from the second column divert anhydrous alcohol. The solution of the desiccant - CaCl2(SrCl2) remaining in Cuba the second column, concentrated in a vacuum evaporator, and then dried in a spray drier to dihydrate and finally dehydrated in a drum drying apparatus. Digidrirovanny CaCl2(SrCl2) returns in the process of drying alcohol. The main disadvantages of this process, I have>(SrCl2) at the stages of regeneration.

A method of dehydration of alcohols and their mixtures /Patent GDR 278336 A1, 1990/. The proposed method to the original degidratirutego alcohol or mixture of alcohols add orthoepy in a quantity equimolar to the amount of contained water. As orthoevra use CH(och3)3CH(OS2H5)3With2H4(Och3)3With2H4(OS2H5)3. A mixture of water, alcohol and arteparon passed through the layer of the cation and zeolite in the H form. As the cation exchange resin using sulfonated polystyrene crosslinked with divinylbenzene, and as zeolite ZSM - 5, dictionary Y or X. After layer of cation exchange resin water-alcohol modified mixture is passed through a bed of anion exchange resin - treated tert-amines styrene-divinylbenzene resin.

The disadvantage of this method is that the resulting dried alcohol (a mixture of alcohols) contains a significant amount of orthoepical that requires further rectification of the product and is the main disadvantage of the described method.

There is a method of dehydration of ethanol /Patent Bulgaria 62885, 2000/ includes adsorption of water from the alcohol pre is Laut in periodically operating a distillation column distillation and then mixed with a new portion of fresh zeolite and so the process of adsorption/distillation continues, not yet achieved the level of water content in alcohol is not more than 0.01 to 0.2%. The disadvantage of this method is the need for repeated process of adsorption/distillation for deep dehydration of alcohol and the use of more deeply on each drying stage fresh portions of the heat-treated zeolite.

The closest to the essence and the technical solution is the way adsorptive excretion of alcohol and water-alcohol mixtures /U.S. Patent 435959, 1982/. This process is the prototype of a water-alcohol mixtures, water-containing 5-30 wt.%, multistage adsorption on the two end adsorbers filled with zeolite adsorbent type And structural type 3A), in the vapor phase (on the alcohol) in a continuous or sequential mode, with the flow of the mixture on top of the adsorbers at elevated temperature - 20-80oC and a pressure of ~ 0.07 to 0.7 MPa get to the final stage of alcohol with a water content less than 2 wt.%. With the increased moisture content in the water-alcohol solution, i.e., when the alcohol content is 5 to 30 wt.%, apply pre-drying (strengthening) of the water-alcohol mixture, using activated carbon. This uncovered a quantity of alcohol after the desorption may be 4 wt. % in alcohol after desorption from the zeolite can be 10 wt.% (example 2, table. 1 the description of the prototype). Given the significant amount of residual alcohol content on the sorbents of both the first and second stage of drying, the described method is proposed to further heat and remove pairs of the alcohol/water after the main desorption process both stages. This needsomeone the number of source water-alcohol mixture and condensed water-alcohol solution is directed into the primary flow. Relatively high residual content of alcohol after a cycle of adsorption on sorbents, for example in the description of example 2 prototype reported extraction of 88 wt.% alcohol "pass") can be considered a significant drawback of the proposed method, resulting in losses of alcohol and significant energy for desorption, condensation, collection and recycling of alcohol-containing intermediates.

The objectives of the present invention was to solve the problems of minimizing losses of alcohol when zeolite drying water-alcohol mixtures, as well as at the stage of preliminary concentration of the raw material in a distillation column. Unlike the prototype method actually zeolite dehydration of water-alcohol mixtures is carried out under conditions, when water and alcohol are in the steam drying alcohol.

The aim of the present invention is a method of dehydration of aliphatic alcohols With1-C3namely methanol, ethanol, n - and isopropanol, mixtures thereof with application in the technology of drying method, the adsorption of moisture on the zeolite and getting "a pass" deeply drained the alcohol product from water-alcohol mixture.

This goal is achieved by the below described method.

The process of deep dehydration of aliphatic alcohols C1-C3is carried out in the vapor phase in the zeolite at temperatures above the boiling point of the water - in contrast to the prototype method, where dehydration of the alcohol is carried out on a zeolite sorbent at temperatures below the boiling point of water. Schematic diagram of the installation for implementing the method shown in the drawing. In the setup diagram is not specified pump, heat exchangers, instrumentation, valves, auxiliary and other equipment that occurs during the industrial implementation of the technology. The installation is a conjugate processing facility, including the rectification column (1) with the plates and the next two in series or parallel adsorber (a-1, a-2). Distillation column of the K-1 is used only if sterzi water to the level of residual moisture in alcohols of 1-6 wt.%. If the moisture content in alcohol or their mixtures does not exceed 8 wt.%, water-alcohol mixture is fed directly into the adsorbers a-1, a-2, bypassing the column By-1.

As the zeolite used for the adsorption drying alcohols, applicable zeolites of structural type, namely MEA (Russian classification, where Me is K, Na, CA, MD, VA, Sr) and 3A, 4A, 5A (American classification) complying with the General chemical composition: IUandAboutAl2O3bSiO2cH2O where Me is K, Na, Sa, SB, BA and Sr in different ratios and combinations thereof; and= 0,82,1, b=1,52,2, C=0,225.

The process of drying a water-alcohol mixtures is carried out under the following technological parameters and modes: - in column K-1 (if using) temperatures top 90105oWith Cuba 115130oWith excess pressure top 0,010.2 MPa, Cuba 0,020.25 MPa, the number of theoretical plates from 8 to 50; in the adsorbers a-1, a-2 adsorption process temperature input (the top of the adsorber) 105140oWith, the excess is p>

Regeneration of the zeolite after the holding pressure of the adsorption process is carried out by vacuum while heating from 40 to 110oC.

The adsorbers a-1 and a-2 can operate in the mode of adsorption/regeneration as parallel (batch) and sequentially (continuous process).

The present invention is illustrated by the following example.

The process is conducted according to the scheme "a pass" on the installation, the main components of which are indicated on the drawing. As raw materials are aliphatic alcohols C1-C3or mixtures thereof. The results of experiments on the dehydration of alcohols is presented in the table.

From the table it is visible - see the results of the experiments 1-11 that for the chosen parameters and modes of implementation of the technology proposed method dewatered alcohol products containing water in an amount of 0.01-0.5 wt.%, when this absolute loss of alcohols at all stages of dehydration, including rectification and adsorption, does not exceed 0.5%, and the degree of extraction of alcohol "a pass" is not less than 96%.

In a comparative experiment 12 the process is conducted on the raw materials and the conditions of experiment 3, only the dehydration of water-alcohol mixture is performed in the adsorbers a-1, a-2, minsterial end alcohol-containing product obtained is not sufficiently drained - the residual water is 3.5 wt. %; absolute alcohol losses when such drying are 1,22%, the degree of extraction of alcohol - 90.3 per cent.

In a comparative experiment 13 instead of the zeolite type And use zeolite NaX (structural type X), and the drying process is carried out on raw materials and the conditions of experiment 4. The achievable depth drying (residual water content of 12.2 wt.%) and large absolute losses alcohols 3.7%, or not allowed to read the selected type zeolite X and the drying method generally effective.

A comparative experiment carried out on 14 raw materials and partly on the conditions of experiment 5, except for the mode of adsorption - the process is not in steam, and liquid (water) phase at the temperature of the entrance to the adsorbers a-1, a-2 90oC. Depth reached dehydration of alcohol (residual water content of 1.7 wt. %) and relatively high loss of alcohol is not allowed to read such an effective way.

Obtained in experiments 1-11 deeply drained alcohol products individually and in mixtures can be used as solvents for organic substances, such as petrochemical, organic and chemical raw materials for various processes of synthesis of substances as additives to motor (automotive, Nol - in the food, medical, cosmetic, biochemical, microbiological, paint industry, as the basis for the production of inks for flexographic printing, household and technical chemistry; isopropanol individually and its mixture with ethanol used as a high-octane additive to motor gasoline, as the basis of solvent inks for flexographic printing, cosmetics, medical industry, as the basis for the production of antifreeze, detergents, cleaning and other technical liquids and household purpose.

Claims

1. The method of dehydration of aliphatic alcohols C1-C3adsorption of water-alcohol mixture on zeolite adsorbent in an adsorber operating in series or in parallel, when applying the mixture on top of the adsorbers at elevated temperature and pressure in the adsorbers, with the use of a zeolite of structural type a, corresponding to the chemical formula: IUandAboutAl2About3bSiO2CH2Oh, where Me is K, Na, Ca, Mg, Ba, Sr in different ratios and combinations thereof; and=0,8-2,1,
b=1,5-2,2,
C=0,2-25,
otlichuy boiling water 105-140oC.

2. The method according to p. 1, characterized in that the content in water-alcohol mixture of more than 8 wt.% the water prior to conducting the distillation of the water-alcohol mixture in a distillation column to the water content in the mixture of 1-6 wt. %.

3. The method according to PP.1 and 2, characterized in that the dehydration of water-alcohol mixture is conducted with the following parameters: column rectification: the number of theoretical plates 8-50; temperature upper 90-105oWith; overpressure top 0.01 to 0.2 MPa; the temperature of the cube 115-130oWith; overpressure cube of 0.02-0.25 MPa; adsorbers: inlet temperature 105-140oC; excessive inlet pressure of 0.02 to 0.18 MPa; the duration of the adsorption cycle 100-800 C.

 

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