CS271761B1 - Method of turbidiforming impurities removal that arise during synthetic spirit production - Google Patents

Abstract

Method of elimination of turbidity forming impurities formed during synthetic alcohol production by direct hydratation of ethylene on phosphoric catalyser, when the technical alcohol, distilled refined alcohol or hydrofined alcohol and technical diethyl ether are formed and turbidity forming impurities are removed by adsorption on a porous sorbent, is characteristic by the fact that a fraction of the impurities leaving the alcohol distillation refinement that is diluted to the amount of 5 to 50 % by weight of alcohol in water by a water-ethanolic fraction or/and by demineralised water or/and by water-alcohol condensate from ethylene hydratation undergoes adsorption. The porous sorbent is regenerated and the oil fraction containing turbidity forming substances is separated.<IMAGE>

Description

The present invention relates to a process for the removal of haze-forming impurities produced by the production of synthetic alcohol by direct hydration of ethylene which is catalyzed by phosphoric acid by adsorption. The process according to the invention restricts the transfer of haze-forming impurities from the node for the production of distilled refined synthetic alcohol to the nodes for the production of technical synthetic alcohol or hydrogenated refined alcohol and to the technical diethyl ether.

Synthetic alcohol is produced in the vapor phase at elevated pressure and temperature by direct hydration of ethylene under catalysis with phosphoric acid, which is anchored on a solid support. The intermediate is an aqueous solution containing 5 to 20% by weight of ethanol, the so-called alcoholic condensate, which contains a number of other organic compounds formed by side and subsequent reactions. Selectivity direct hydration is mainly influenced by the quality of ethylene, the reaction temperature, molar ratio H ₂ 0: C ₂ H _4, speed of the mixture, the porous structure of the catalyst and the concentration of P ₂ ° 5 · ^{z to} y ^{with: L: I: ka 'characterized ch} dopant is lihovodném condensate represented by diethyl ether to 2 wt.%, further acetaldehyde, acetone, methyl ethyl ketone, and higher alcohols, predominantly _C4.

Other undesirable impurities which are practically insoluble in water are haze-forming impurities in an amount of about 0.03% by weight. based on ethanol. They are especially alkanes up to

C ₂ q and higher alcohols up to C ^ ·

The content of alkanes is also increased by incomplete separation of machine oils.

The use of other production steps depends on the required quality of the final products. The following production processes are adopted operationally:

The production of synthetic alcohol consists of distilling the ethanol at about 90% by weight. In this process, almost all of the accompanying impurities pass into the product. A product of a higher grade is obtained by distillation, which reduces the diethyl ether content to about 0.1% by weight. The resulting ether fraction can be further processed into technical diethyl ether. The oxidation stability of the alcohol can be increased by the hydrogen refining of aldehydes and ketones to the corresponding alcohols. Various extractive distillations of spirits condensate are also adopted. E.g. according to the procedure described in the author's certificate No. 156 011, the volatile constituents of acetaldehyde, ether, ectones, part of higher alcohols and haze-forming impurities are converted into distillate in the distillation, the so-called impurity fraction. The diluted pre-purified ethanol solution is concentrated in a further distillation step with lateral withdrawal of higher alcohols to about 94% by weight. The content of these higher alcohols in the product does not exceed 100 ppm. The disadvantage of this process is that, due to the relatively high ethanol and diethyl ether in the fraction of impurities and the ethanol in the side flue, these streams have to be used for further processing and are therefore introduced into the technical alcohol production node. . At the same time, an increase in the proportion of distilled refined alcohol causes greater pollution of not only technical alcohol and hydrogenated refined alcohol, but also the transfer of some impurities to the technical diethyl ether.

Limiting the solubility of haze-forming impurities in water is used to characterize the quality of alcohol. Typically, the haze in the final product diluted with water is determined to be an alcoholic ratio: · water = 2: 3, which corresponds to an ethanol concentration of 40% by weight. Hazardous impurities are the cause of, in some of its other chemical applications, higher molecular weight compounds covering heat exchange surfaces and catalysts in lesser-quality alcoholic species. When cleaning car windshields with these types of spirits, its transparency is reduced, especially in rain and backlight.

It has been found that haze-forming impurities can be separated only from aqueous solutions containing up to 40 to 50% by weight of ethanol. Centrifugation of these solutions is poorly effective. ExtrdcCS 271761 Bleaching haze-forming impurities into non-polar solvents can achieve a considerable degree of purification. However, a complicating factor is the fact that the diethyl ether present is also extracted. Another complication is the high impact on the purity of the extraction solvent, as there is a risk of secondary contamination and the need to remove residues of the extraction solvent. The procedure for reducing haze-forming impurities described in the author's certificate no. 227 237 utilizes an increase in the relative volatility of haze-forming impurities suspended in alcoholic condensate. A refinery gas such as nitrogen or C 1 -C _M hydrocarbons is used to displace them. This process cannot be used in the production of technical diethyl ether from synthetic alcohol as the evaporation of ether into the refinery gas is considerable.

In addition to the colloidal form of haze-forming impurities, these substances are contained in the alcoholic condensate as well as in aggregate form into larger droplets which are deposited on the surface of the apparatus and irregularly penetrate into distillations.

Effective adsorption of colloidal haze-forming substances on porous sorbets is virtually impossible for large volumes of alcoholic condensate to be processed. For example, in the production of 10 t of ethanol per hour, the volume of alcoholic condensate is about 80 nP / h.

It has now been found that these disadvantages can be eliminated or substantially reduced by the method of the invention.

A method of protecting haze-forming impurities resulting from the production of synthetic alcohol by the direct hydration of ethylene in the presence of phosphoric acid as a catalyst, which produces technical synthetic alcohol and / or distilled refined, possibly also hydrotreated synthetic alcohol and technical diethyl ether. with water as the extracting agent and the hydrotreating takes place on the fixed catalyst by the action of hydrogen and the haze-forming impurities, which are sparingly soluble in water, are adsorbed on porous sorbets, according to the invention is diluted to 5 to 50 wt. an aqueous solution of alcohol, preferably to 20 to 40 wt.%, an aqueous-alkaline fraction having an ethanol content of up to 40 wt. or with demineralized water, preferably by a lateral withdrawal from distillation refining or by distillation condensate from direct ethylene hydration, and the porous sorbent is regenerated after exhaustion of its sorption capacity. Alcoholic condensate with an ethanol content of 5 to 20% by weight. resulting from the direct hydration of ethylene, it can be adsorbed prior to aggregate haze-forming impurities prior to use for dilution. An oil fraction containing haze-forming impurities is separated from the aqueous condensate resulting from the regeneration of the porous sorbent.

Thus, the reduction of haze-forming contaminants throughout the synthetic alcohol purification system is achieved by adsorption of haze-forming substances from a relatively small volume of the diluted fraction of impurities. This is based on the finding that effective separation is possible in aqueous solutions with an ethanol content of not more than 50% by weight. and further that the impurity fraction from distillation refining of alcohol contains a major proportion of haze forming agents. For dilution, use an aqueous solution of synthetic alcohol. Advantageously, a side off-take from distillation refining, distillery condensate or possibly demineralized water can be used for dilution.

Adsorption of clouding agents is performed on porous sorbents of the type: activated carbon, diatomaceous earth or zeolite. After the sorption capacity has been exhausted, the absorbed turbidity impurities can be distilled off and the properties of the regenerated sorbent recovered, or the serbent can be exchanged for unused ones. The cycle of regeneration or sorbent exchange is selected such that at the end of the cycle the haze content of the technical synthetic alcohol is reduced compared to the non-adsorption state.

CS 271761 Bl

Aggregate haze-forming impurities forming an oil layer on aqueous solutions are preferably adsorbed. The pretreatment of the spirits condensate significantly reduces the adsorption load of the colloidal haze-forming impurities that is included in the impurity fraction stream.

The process according to the invention is illustrated in the diagram of Fig. 1. Alcoholic condensate (LVK) from the direct hydration of ethylene is fed to the distillation line 2. Optionally, there is a dual adsorption pre-treatment 2 arranged in parallel, where one adsorber is in operation and the other in steam regeneration via line 2; Extraction water 7 is fed to the refining column 6 via line 7. Destialční residue column 2 ^te fed to a rectification column j)> distillate of this column is a synthetic alcohol distillation 10th refined distillate from column 6 is the fraction of impurities 9, which is diluted with a side flue 11 of column 2 and the concentration of the ethanol is diluted optionally portion LVK The diluted mixture 26 enters a doubled adsorber 12 arranged in parallel, where one adsorber is in operation and the other in steam regeneration via line 13. Into the process alcohol production column 16, in addition to said part LVK 5, is introduced. The distillate 17 is de-etherized in distillation column 18, the distillate being technical diethyl ether 22. supplying hydrogen via line 21, the outlet being synte Hydrogenated refined alcohol 22. Waste water is removed from the distillation columns 8 and 16 as distillation residue via lines 24 and 25. Alternatively, a portion of the deuterated technical alcohol 27 produced can be returned to the feed of distillation refining. After the adsorption capacity of the adsorbs 2 and 12 has been exhausted, the combined water condensate 2B is fed to a separator 29 where the waste oil fraction of the haze-forming impurities 30 and the waste water 31 from the bottom exit.

Example 1

Table 1 shows the mass balance of the streams from the scheme in Fig. 1 and the ethanol content characterizing the streams. Furthermore, the balance of haze-forming impurities in individual streams is given, which is based on the content of haze-forming substances in the spirits condensate.

Table 1

current No current name total current (kg / h) ethanol content ZN content (kg / h) (wt%) (kg / h) (wt%) 1. LVK from direct ethylene hydration 71 429 10 000 14.0 21.4 0.03 4. LVK into distillation refining 53 572 7 500 14.0 16.1 0.03 5. LVK into the production of technical alcohol 17 857 2 500 14.0 5.4 0.03 9. fraction of impurities 1 603 1 203 75.0 15.3 0.95 11. lateral exhaust 1 441 154 10.7 0.8 0.05 14. LVK for dilution 525 73 14.0 0.2 0.03 26. entry into adsorption 12 3 569 1 430 40.0 16.3 0.46 15 Dec after adsorption 3,553 to 3,554 1 430 40.0 0.2 to 1.6 006 to 0 , 045 Pozn.í The values for the stream 15 are sorbent to acceptable I move in the given interval according to the capacity and capacity.

CS 271761 Bl

Example 2

Comparison of the content of haze-forming impurities in synthetic alcohol without adsorption and with adsorption according to the invention, when the proportion of synthetic distillate distilled is 75% by weight. of total ethanol production.

Table 2 shows the values for currents 2 ⁺ 15 and 23 of the diagram in Fig. 1.

«Table 2

Current dimension without adsorption with adsorption (during the cycle) Hazardous impurities content kg / h 21.7 5.6 to 7.0 at the entrance to the column techn. if- % wt. 0.10 0.026 to 0.033 hu 16 Haze in technical alcohol current puzzle pieces 4 500 1 200 to 1 500 23 (dilution to 40% w / w nefelomet. nolu) Evaporator: mg / + technical alcohol 23 10 4 technical diethyl ether 19 10 4

The effect of the process according to the invention is that the transition of haze-forming impurities from the production of synthetic distillate refined to industrial and hydrotreated alcohol and to technical diethyl ether is reduced, and the evaporator is also reduced in these products. This will significantly increase their utility properties. Further advantages are that the reduction of the activity of the catalysts for the hydrotreating of alcohol and industrial diethyl ether is reduced, and the wastewater contamination by organic matter is reduced by separating the oil phase of the haze-forming impurities from the process.

Claims (3)

SUBJECT OF THE INVENTION 1. A process for the removal of haze-forming impurities resulting from the production of synthetic alcohol by direct hydration of ethylene in the presence of phosphoric acid as catalyst, which produces technical synthetic alcohol and / or distilled refined or possibly hydrotreated synthetic alcohol and technical diethyl ether. extractive distillation with water as the extracting agent and hydrogenation refining takes place on a fixed catalyst under the action of hydrogen and haze-forming impurities, which are sparingly soluble in water, are removed by adsorption on porous sorbents, characterized in that impurities fractions leaving the distillation refinery are subjected to adsorption; % aqueous alcoholic fraction with ethanol content of up to 40% by weight is diluted to 5 to 50% by weight of an aqueous alcoholic solution, preferably to 20 to 40% by weight. and / or with demineralized water, preferably by side withdrawal from distillation refining or by distillation condensate from direct hydration, and the porous sorbent is regenerated after exhaustion of its sorption capacity. 2. A process according to claim 1, wherein the alcoholic condensate having an ethanol content of 5 to 10 is used CS 271761 Bl 20% by weight, resulting from the direct hydration of ethylene, adsorbs pre-treated aggregate haze-forming impurities. 3. Process according to claim 1, characterized in that an oil fraction containing haze-forming impurities is separated from the water condensate resulting from the regeneration of the porous sorbent.