Method of freeing phenol from acetol

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of phenol via acid catalytic decomposition of cumene hydroperoxide followed by isolation of phenol from decomposition products and purification of phenol to remove trace impurities including acetol. Purification of phenol is accomplished through hetero-azeotropic rectification with water. Acetol is isolated as a part of liquid-phase side stream from semiblind plate located within exhausting section of hetero-azeotropic rectification column. Side stream is supplemented by cumene and used to supply stripping column, from which fraction of acetol/cumene azeotropic mixture is taken as distillate and residue is returned under semiblind plate of hetero-azeotropic rectification column to be further exhausted. From the bottom of the latter, crude phenol is withdrawn and passed to final purification from the rest of reactive trace impurities. Acetol/cumene azeotropic mixture is subjected to heat treatment at 310-350°C, which may be performed in mixtures with high-boiling production waste or in mixtures with bottom product of rectification column for thermal degradation of high-boiling synthesis by-products, which bottom product is recycled via tubular furnace. Above-mentioned semiblind plate, from which side stream is tapped, is disposed in column zone, wherein content of water is minimal and below which contact devices are positioned with efficiency at least 7.5 theoretical plates. Side stream with cumene added to it is passed to the vat of stripping column with efficiency at least 15 theoretical plates.

EFFECT: minimized content of acetol in purified phenol and reduced power consumption.

5 cl, 3 dwg, 6 tbl, 4 ex

 

The invention relates to the technology of organic synthesis, namely the production of phenol, obtained jointly with acetone by decomposition of gidroperekisi hydroperoxide (CHP), catalyzed by acid (usually sulfuric acid). Decomposition GPK - exothermic reaction. The heat of reaction is convenient to take, keeping the temperature about 60°C due To the evaporation of acetone, the required number (recirculate) is injected into the concentrate of the CCP, the main components of which (dry. wt.%): not into the cumene - 18-20, PCG - 76-82, by-products of synthesis 2-5. Some industrial plants to concentrate the CCP sent to the stage of decomposition, add the decomposition products of the CCP.

In the decomposition process of the CCP produced acetol (1-hydroxy-2-propanone, acetylcarbinol, hydroxyacetone), the content of which in the decomposition products of the CCP when used as recirculate acetone can reach up to 0.2 wt.%, because acetal is formed by the conversion of acetone in an acidic reaction medium via the intermediate formation of 2-hydroxy-semiproletarian. Acetal in the process of isolation and purification of phenol modern industrial methods interacts with it to form 2-methyl-benzofuran (2-MBF), which is difficult to separate from phenol and whose presence in the product phenol affects the rate of color as a trademark phenol, proizvodimyh products thereof. /Vel. "Industrial method of obtaining high purity phenol". The master's thesis. SPb., The LTI, 2001/.

There is a wide variety of technological schemes of phenol recovery from the decomposition products of the CCP and its clearing up to required standards. /Wamesolasonse and other "Modern state and ways of intensifying the production of phenol and acetone Kukolnik method". The overview. Series: Petrochemistry and sleeperette, vol. No. 6, M, Tsniiteneftehim, 1988/, but in industrial practice, this process is mainly carried out by two technological schemes.

On the first of them neutralized and separated from the water-salt solution decomposition products of the CCP act in a distillation column, where they are allocated acetone fraction, in the process of further processing which are trademark acetone. The product stream from the cube column selection acetone fraction is sent to the column, which is in the form of the cubic product highlights high-boiling impurities and the distillate - phenolic fraction is sent to the column heterotetramer rectification. In this column, by adding water, distills the hydroperoxide and organic impurities, forming water azeotropic mixture boiling point which is lower than the azeotropic mixture of the water-phenol". With the number entered in this column of water should not exceed the necessary m the area, in order not to involve the distillation of the excess amount of phenol. After condensing the distillate from this column is stratified into the water layer flowing on the irrigation of the column, and the organic layer, which is sent for further processing to identify cumene, recycled to the stage of synthesis of the CCP, and alpha-methylstyrene (AMS). AMC has an independent value, but usually hereroense obtaining cumene, is also recycled to the stage of synthesis of the CCP. From the bottom of the column heterotetramer rectification output phenol raw sent for further processing with the aim of obtaining phenol marketable condition. /Ahurry and other "Selection schemes improve the quality of synthetic phenol". RE Refining and petrochemicals, No. 10, 1966/.

According to another scheme, the decomposition products of the CCP, coming into the first distillation column and separated with getting in the distillate large fractions which contain, in addition to acetone, the major amount of cumene and alpha-methylstyrene. The completeness of extraction of cumene and AMS is achieved in the process heterotetramer distillation with water, which is contained in the power of the column, it comes with irrigation (oil layer from the separation of condensed distillate) and with a part of the re-circulating in the power of the column of the water layer. From the cube this column displays the phenol stream, which is then added the account under the scheme, similar to the above, i.e. from the phenol stream is separated high-boiling impurities, and then use the method heterotetramer rectification perform purification from organic impurities and, thus, receive the phenol-raw /Patents USA: 3205272, 1965 and 4283568, 1981/.

When working on the second version is more complicated technological scheme of the process of getting a trademark acetone, but the content acetal in the phenolic fraction, derived from a cube, first as the raw material of the column is lower than the first version (0.1 to 0-2%). However, even when the processing of the decomposition products of the CCP under this scheme, the content of acetal in the crude phenol reaches 200 ppm.

Both the first and the second circuit have nodes that are common to both schemes:

a) site thermal treatment of high-boiling by-products of synthesis, where the temperature 310-340°they pyrolysate with additional quantities of phenol and cumene and AMS. /Patent RF 2056400, 1996/. This site is available on most modern industrial plants;

b) site cleanup phenol raw, with bringing his condition to the required standards. This site is available on all industrial installations and, as a rule, consists of a section of the catalytic processing of phenol raw and section of the rectification of the received catalyzate. The purpose of the catalytic processing is the transformation contained finale raw traces unsaturated, carbonyl (including acetal) and other reactive compounds, mainly in the high-boiling products, which were separated from the phenol by distillation.

Known methods for removal of phenol raw from MicroProse.

For example, traces of contaminants are removed by heating phenol raw with a small amount of strong acid /Patents Germany 1126887, 1962/, or by heating phenol raw with a mixture of sulfuric acid and a strong oxidizing agent with bichromate of potassium or hydrogen peroxide. /Patent Romania 47812, 1963, the Japan Patent 18975, 1971/, or by heating it with air or oxygen in the presence of concentrated sulfuric acid /Patent Czechoslovakia 125539, 1967/.

A common disadvantage of the above known methods is the high corrosivity of the environment, requiring the use of expensive corrosion resistant materials.

This lack deprived of the ways, where the processing of phenol raw is on heterogenic catalysts: cationic /A.S. USSR 265104, 1970/; alumina /U.S. Patent 3029294, 1962/; aluminosilicates /Patent England 1148907, 1969/; zeolites /Patent RF 2111203, 1993, U.S. Patent 5502225,1996,/.

The General lack of purification of phenol-from raw traces using the above catalysts is that in the presence of acetal reacts with phenol, forming a 2-MBF, which is difficult to separate from pheno is a, in addition, it is lost phenol, i.e. decreases the selectivity of the process.

In U.S. patent 6486365 (2002) phenol raw, contaminated carbonyl compounds (including acetal in the number of 200-1000 ppm) and other impurities, it is proposed to enter into contact with katalizatorom "hydrotalcite-type (HTM) with the General formula: Mg2·Al2(OH)4x+4CO3·multidot·n H2O working effectively in the temperature range 40-400°With (preferably, 210-220°). For a contact time of 30 min at a temperature of 215°acetal converted not less than 94% to its residual content in the catalyzate not more than 1 ppm, 2-ICF becomes not more than 1.5% acetol that provides its concentration in the catalyzate not more than 20 ppm. Further, the products of transformation of acetol and other impurities are separated by distillation, providing the required condition trademarks of phenol.

The disadvantages proposed in this patent solutions are as follows:

1. The need for processing large amounts of source material.

2. A large number of used catalyst (processing time 30 min) and, accordingly, large volumes and weight of stainless steel.

3. The need for regeneration of the catalyst, which is carried out by washing with water, and then by treatment with air or nitrogen at a temperature of 200-600°With (before occhialino, at a temperature of 400° (C)what are the nodes on the excretion of nitrogen or air is compressed and heated to the desired temperature.

4. Increasing environmental pressure on the environment, appear as waste water and exhaust gases from the regeneration of the catalyst.

In U.S. patent 5414154 (1994) in order to reduce the content of acerola offered phenolic fraction to handle amines, and then clean strong cation exchange resin to remove residual acetal and other reactive impurities. As a result impurities, including 2-MBF, turn into a high-boiling compounds are separated from the phenol by distillation.

The disadvantages of this method include: introduction to the technological scheme of additional site that does not provide the necessary degree of purification of phenolic fraction from acetal, and the necessity of consumption of expensive reagents.

In U.S. patent 6066767 (2000) offers clear from acetal decomposition products of the CCP at the beginning of the technological scheme of processing, namely at the stage of neutralization of sulfuric acid contained in the decomposition products of the CCP. In existing industrial installations neutralization of sulfuric acid is usually carried out with caustic soda. The alkali is introduced into the circulating solution of sodium sulfate, bringing its concentration close to saturation when the N environment 6-7 and a temperature of 50-55° With, thereby "Visalia" organic compounds in the equilibrium oil layer containing about 10% wt. water. The oil layer, which contains up to 2000 ppm of acetol, acidified to PH=4.5 to 5.0 prepare the chin from him aqueous saline solution and sent for further processing on the extraction and purification of target products. In recirculating solution of sodium sulfate is distributed phenol, acetone, aldehydes and other water-soluble compounds, including acetal, the concentration of which is 1500-2000 ppm. Offered in a circulating water-salt solution to add excess alkali to its concentration in the range from 0.1 to 20% wt. (preferably, 0.5 to 1.0% wt.) followed by exposure to capacity-doznavatel at a temperature of 80-130°C for 5 hours. If all these conditions it is possible to achieve nearly complete conversion acetal and acetaldehyde in high-boiling compounds (mainly in trioli). After this, the solution from the tank-desravines, in which the content of acerola minimized until the complete absence cooled to a temperature of 50-55°C, neutralized with sulfuric acid to obtain a pH equal to 6-7. This solution then enters the mixing with the products of decomposition of the CCP and is the extractant in relation to acetol contained in them. Thus, set a new equally Vesna situation, so the content of acerola in equilibrium with water of an oil layer that is sent for further processing, is reduced to 600-700 ppm with a corresponding (2-3 times) decrease of its concentration in the crude phenol selected from the decomposition products of the CCP and sent to finish the cleanup.

The disadvantages of the decision in this patent includes the following:

1. Increased consumption of reagents: alkali for alkalization of circulating water-salt solution with before mixing with the alkali pH=6-7, and then, after the alkali treatment, - sulfuric acid to neutralize the excess alkali to bring the pH to its original value.

2. A corresponding increase in the number of production waste - water solution of sodium sulfate contaminated water soluble organic impurities (including trioli obtained from acetol), as well as the increase in the volume of wastewater and the cost of their processing.

3. Energy costs for heating circulating water-salt solution and cooling to the initial temperature.

4. Involvement in the reaction of alkaline condensation except acetal and acetaldehyde and acetone (the content of which in water-salt solution reaches 1% wt.), that leads to a noticeable reduction of the yield of acetone at an equivalent increase in the output side preproduction, in particular oxide mesityl, lane is walking in the oil layer.

5. Maintaining a system of purification of phenol raw from residual acetal, i.e. the complexity of the technological scheme by introducing a node reagent purification of water-salt solution contained acetal.

Advanced technology for removal of acetol of water-salt solution is proposed to handle it with oxygen (air) in an alkaline medium (the concentration of the alkali 0.3 to 0.5% wt.) at a temperature of 70-110°C. In the presence of a specified quantity of alkali phenol fully associated it with the formation of the corresponding phenolate alkaline agent. In the absence of free phenol oxidative processes has accelerated sharply, and the time of exhaustion of acetal contained in the water-salt solution significantly (almost 3 times) decreases. /ELA and other "Catalytic oxidative conversion of acetol in an aqueous solution of sodium sulfate in the presence of phenol." XIII-th international conference "Reagent-2000". The abstracts. Tula, ed. TPGU, 2000/.

However, the proposed solution does not completely obviate the disadvantages inherent in the technology of U.S. patent 6066767. Moreover, the technological scheme is complicated by the addition of air compressor, reactor oxidation system for neutralization of exhaust gases while increasing their total volume (in addition to the exhaust gases of Aquileia cumene).

In patent application US 2002/A (filed March 4, 2002, published 5 December 2002), the products of acid-catalyzed high-temperature decomposition of alkylimidazole, including the CCP, with the temperature not lower than 100°With (preferably 110-150° (C)proposes to enter into contact first with water, bringing its concentration in the products of decomposition to 8 wt.%, and then with sodium phenolate, obtained by treating phenol with caustic soda with a concentration of 10-20%, and maintaining the resulting mixture in an isothermal reactor for at least 10 minutes (up to 10 hours) at a pH of at least 8 (preferably 10-12). The reaction mixture after the reactor is cooled to 40°and, if necessary, neutralize the alkali to obtain a pH of about 8. As a result neutralized products of decomposition of the CCP, coming to the stage of selection of target products, the content of acerola decreased from the initial concentration at the inlet of the reactor 1200 ppm to end at the outlet from the reactor - 30-400 ppm (depending on pH, temperature and time of processing).

The disadvantages of the proposed solution are as follows:

1. The high pH environment of the decomposition products of the CCP, as in the reactor phenolates" treatment (pH=10-12), and in these products, next coming to the extraction and purification of acetone and phenol (pH about 8), which leads to the formation diacetone alcohol and oxide mesityl - products of the process p is euromania acetone, catalyzed by alkalis.

2. The solution of water in phenol and phenol in water are characterized by a pH in the range of 4.5 to 6.5. In the proposed solution the decomposition products of the CCP after treatment with alkali metal phenolate for further processing are transmitted at pH about 8, i.e. with them in appreciable quantities will be supplied phenolate of an alkali metal, with corresponding losses of phenol from industrial waste, to prevent which it is necessary to build a special installation.

3. In accordance with paragraphs 1 and 2, there is additional loss of alkali, and in the construction of plants for the recovery of phenol from the phenolate - additional losses acid.

4. When the acid regeneration of phenol from alkali metal phenolate (PP and 3), additional amounts of salt-containing wastewater.

5. Because the proposed method in the cleaning products remains acetal is still critical to decimate from him phenol with bringing trademarks of phenol to the required condition.

In which the prototype of the present invention patent application U.S. 2002/0066661 A1, published on 6 June 2002, proposed cleanup of phenol from acerola (in the text of the application used synonym - hydroxyacetone) be made from mixtures containing acetal, cumene, water and phenol, for example, from the product mixture obtained by the decomposition alkylaryl is peroxides (for example, the gidroperekisi cumene - CCP), by fractionating this mixture, separating the phenol in the form of the cubic product of distillation columns, the contents of acetal which does not exceed 300 ppm.

Patent application prototype actually describes the situation arising in the process of decomposition products of the CCP in the second scheme described above (pages 2 and beyond). Unlike the first scheme, acetol after the first, during the decomposition products of the CCP, distillation columns is distributed so that most of it goes in a wide distillate fraction, hampering its further processing, and the content of acerola in VAT (phenolic) the flow is markedly reduced not more than 300 ppm of the prototype and not more than 200 ppm - other sources of information.

The main weaknesses of the proposed prototype is the complexity of the technological scheme and the fact that it does not solve the problem of removal of acetol of phenolic stream output from the cube first distillation column.

This requires:

a) to free it from residual impurities forming polizeitruppe mixture with water;

b) one way or another to remove acetal (and other residual impurities) of phenol raw.

The purpose of this invention is to develop technology that minimizes (up to the complete exclusion) entering acetol the phenol-raw devoid of the disadvantages inherent in the prototype, and implemented with minimal capital and operating costs.

The proposed technology, in accordance with the present invention, is based on assumptions, which are outlined below.

1. Acetal does not form azeotropic mixture with water /Aristovich and other "study of the process of rectification and phase equilibrium liquid-vapor systems phenol-water-hydroxyacetone and phenol-water-alfamethylstyrene". Russian journal of applied chemistry, volume 76, issue. 2, 2003/ and mixed with it in all respects /chemist's Handbook, so 2. HOSNI Chem. lit. L-M., 1963/.

2. Experimentally (by the method of distillation analysis /Weblogin. "Azeotropic and extractive rectification". Ed. 2-E. L., "Chemistry", 1971/) we found that acetal forms cumene homogeneous azeotropic mixture of minimum boiling point (135,9°at 755 mm RT. century), in which the content of acerola is 39.8% wt.

These data explain why in the first variant of the technological scheme of allocation of phenol (see page 2) when cleaning phenolic fractions from organic impurities by the method of the hetero-azeotropic distillation of acetal coming in the power of the column almost completely in the phenol-raw output from the cube of the column. It is obvious that the irrigation water layer obtained after separation of the distillate, ver the inner part of the column working against acetol mode extractive distillation, moreover, water is a separating agent.

According to another process in the column of the primary separation of the products of decomposition of the CCP, which also operates in the mode heterotetramer rectification (the second variant of the technological scheme), but irrigated oil layer. In this case, in the column occurs physico-chemical situation, due to which a significant number of acetol excreted in the distillate from this column per node processing a wide acetone fraction and the content of acetal in the phenolic fraction, derived from a cube column, is reduced accordingly (see page 3).

3. On the basis of the assumptions set forth in claim 1, columns heterotetramer rectification to half-deaf plates, located in the comprehensive section of this column, you can bring in food the Stripping column, the entire descending liquid stream from which to remove acetal in the composition of the distillate fractions and the residue from the Stripping column to return the half-deaf plate of the main column. However, experimentally it was found that the selection of acetol directly from this thread is a difficult task. When rectification in continuous mode on laboratory column efficiency 40 theoretical plates (with full refund of phlegmy) with the supply of raw materials (artificial mixture obtained by adding to the phenol 0.2% acetol) among the inu columns, when selecting distillate to about 0.25% of the submitted materials and reflux numbers up to 200 (at the limit of zahlebyvayas), the content of acerola in Cuba columns remained at the level of 300-400 ppm, which indicates very low relative volatility of acetol in the system phenol-acetal.

It is known that in such cases it is advisable the use of separating agents.

As such was tested in the cumene - component matching well with the technology of the process and, as was shown above, forming with acatalog azeotropic mixture of minimum boiling point. In addition, cumene forms an azeotropic mixture with phenol, with a boiling point 149°that facilitates its removal from mixtures with phenol adding some excess cumene. The water content in the zone of half-deaf plates should be minimized until the complete absence, as cumene forms azeotropic mixtures: a binary with water and a triple with water and phenol /Bwikora and other "Azeotropic mixture". The Handbook. (Edited Scholarone.com). L., "Chemistry", 1971/, and when water gets into power the Stripping column increases the consumption of cumene and the output of the distillate fractions.

In razgonki conducted on laboratory column efficiency 15 theoretical plates with a reflux ratio of 3 mixture composition (% wt.): acetal - 4,0; cumene - 6,0; phenol - rest, were obtained fractions: NK - 145° And 145-155°With an average compositions (wt.%), first fraction: acetal - 42,1; cumene - 57,4; phenol - 0.5 and the second fraction: acetal - 1,8; cumene - 93,7; phenol - 4,5. The residue contained in the cube: cumene - 2 ppm and acetol about 1 ppm. Further experiments were carried out on the same column, with the difference that they were held in continuous mode power supply directly to the cube of the column, and as a raw material was used VAT residue columns heterotetramer rectification industrial installations running on the first processing circuit decomposition products of CPC (with an initial allocation of the decomposition products of the CCP narrow acetone fraction, i.e. with an increased content of acerola in phenol raw). The composition of the sample: acetal - 1560 ppm AMS - 64 ppm, 2-ICF to 6 ppm, unidentified impurity - 98 ppm, phenol - rest. To this raw material was added acetal, and its content in the mixture increased to 2000 ppm, and the cumene to its content in the mixture is equal to 3000 ppm. Reflux the number, as in the experiments, in periodic mode is maintained equal to 3. In the following results were obtained: yield of distillate from the submitted materials is 0.58%, and its composition (% wt.): acetal - 34,1%; cumene - 50,9%; phenol - 14,3%, AMS - 0.7 percent. The residue contained in the cube: cumene - 113 ppm AMS - 28 ppm, acetal - 21 ppm. The residue was flown on the same column continuous mode with the supply of raw materials in it with the middle, selection of distillate in the amount of 0.25% wt. from the submitted materials and reflux about 175. Reflux the number given to the working conditions of industrial column mode heterotetramer rectification, was calculated by the heat balance of the column, based on the ratio of threads on its lower plates, wherein the ratio of the downward liquid flow to the phenol crude output from the cube column, close to 1.5.

When these conditions are met in the composition of the cubic product output from the column was a lack of cumene, and the content of acerola did not exceed 1 ppm.

When finding ways of recycling the distillate obtained in the Stripping column (DSC), we investigated the possibility of exposure to high temperatures, since in most installations, there is a unit of thermal splitting of high-boiling by-products of synthesis (EPS).

First, in the first cycle of experiments, we investigated the heat treatment directly DSK.

The experiments were conducted in sealed vials with a volume of 15 ml, made of stainless steel and equipped with a thermocouple, a pocket which is built into the lid of the capsule. Capsules designed for temperatures up to 450°C and pressure up to 250 bar. In the ampoule was loaded with 10 ml of the investigated product, and they were placed in a sand bath, in which the preset temperature is automatically maintained by the impulse from the term the pair, installed in the "bath".

During the experiments were recorded temperature and time capsules "bath", and the time for heating the contents of the ampoule to the specified value was 5-8 minutes and, as a systematic error, was not taken into account when evaluating the results of the experiments, calculated for several hours. The range of the investigated temperature in all experiments was 310-350°C (average temperature deviation from the target was not more than 1.5%).

After a predetermined time of heat treatment ampoule was removed from the bath and immersed in a vessel cooled with running tap water with a temperature of 9-12°C. the Average results of the heat treatment in the first cycle are shown in table 1.

Table 1.

The results of the heat treatment in the first cycle of experiments
The content in the original and heat-treated product*
№p/pT-RA °Time, hour.MG**AcetalThe cumenePhenolAMC2-ICFNS***
0---34,150,914,3 0,7--
13101the 7.85of 5.6851,725,900,269,4219,17
23102RS 9.691,0951,875,440,2111,3220,36
331039,230,3252,42a 4.830,17to 11.5220,61
4310410,290,0852,534,590,15of 11.6920,70
53105-<0,01****-----
63106-23 ppm-----
73107-<1 ppm-----
833018,665,08to 51.645,27 0,228,7220,41
9330210,710,6851,805,020,1910,2621,36
103306-<1 ppm-----
1135019,184,6751,124,860,19by 8.2221,76
12350211,340,3451,684,420,179,5422,72
133505-<1 ppm-----
Notes: * Khromatograficheskoe definition in % of the mass. dry matter (or ppm).

** MG - methylglyoxal. *** NA - unidentified compounds.

**** Changes in the concentration of other components is less than the error of the analysis.

As can be seen from the data placed in table 1, in heat-treated DSK almost completely preserved, a hydroperoxide, a significant portion of the phenol and the AMC, the content of AC is Tola is reduced, almost to a complete absence.

Heat-treated DSK can be returned to the process, for example, adding to the decomposition products of the CCP. Thus the presence in its composition of 2-MBF will not affect the quality of the phenolic fraction allocated to the column of her emancipation from the high-boiling by-products of synthesis (EPS), because the main number of 2-ICF coming into the system with catalytic decomposition of the CCP, is removed from kubovy the product of this column.

In the next cycle, we investigated the possibility of processing the DSC when it is heat-treated on site thermal cleavage of the UPU. The basic apparatus of this node - distillation column, in the power which serves the UPU, and tube furnace through which circulates CBM product of this column (KP)and its carrying amount is excreted from the system. In distillate fractions are selected regenerated cumene, AMS and phenol.

The studies assessed the results of the heat treatment DSK mixed with circulating KP inlet tube furnace under the following conditions: temperature 310-350°ratio DSK:KP=1:80, 120, 240 (which corresponds to the ratio of circulation KP through the tubular furnace 1:10, 20, 30). In the analysis of heat-treated mixtures was determined only the content of acerola, since changes in the concentrations of the remaining components of the mixture were comparable with the error of Ana is iza, and due to the short-term temperature effects take into account the total time of high-temperature exposure (including heat-up time of the vials to a predetermined temperature).

In ampoules were loaded typical CBM product (KP)obtained in an industrial setting, with composition (wt.%): phenol - 8,6; acetophenone - 1,4; Foron - 1,9; dimethyl-phenylcarbinol - 1,6; 2-MBF - 16,3; dimethylcarbinol - 1,6; cumylphenol - 12,6; dimers AMS - 5.5 and resin - 50,5; which in a predetermined ratio were mixed with DSK.

The results are shown in table 2.

330
Table 2.

Heat treatment conditions and the content of acerola (AL) in heat-treated mixtures KP and DSC ppm.
Abbreviations: BP - heating time; processing time; OB is the total time, minutes
№ p/pKP:DSKT-RA °BPINSAL
180310551037
21603105101516
324031051520<1
480731021
51603307815<1
6803508715<1

As can be seen from the data placed in table 2, when the heat treatment DSK in a mixture of high-boiling products of the synthesis process is considerably accelerated.

Next was a series of studies with regard to the processing of products of catalytic decomposition of the CCP, in which there is a host of thermal decomposition of high boiling products.

In ampoules in a predetermined ratio were loaded mix DSK with high-boiling by-products of synthesis (EPS)obtained in an industrial setting, with composition (% wt.): the alkyl benzenes - 0,2; cumene - 0,8; AMS - 0,3; phenol - 12,2; dimethylphenylcarbinol - 4,3; acetophenone - 13,6 higher ketones - 3,5; Foron - 1,5; 2-MBF - 8,5; dimers AMS - 13,8; cumylphenol - 31,3; resin - 9,9. The mixture was subjected to heat treatment in the temperature range of 310-350°for a given processing time. Since the above-mentioned temperatures is thermal decomposition of many of the compounds included in the composition of the EPS (AMS dimers, dimethylphenylcarbinol, cumylphenol, in part, resin), obtaining cumene, AMS, phenol, and is etona, (less than significant quantities of other substances), and subjected to heat treatment mixtures is their recombination with participation of acetol, the removal of which is the aim of the proposed operations, the analysis of the products of thermal processing in the previous cycle, was determined only the content of acerola.

The results are shown in table 3.

0,43
Table 3.

Heat treatment conditions and the content of acerola (AL) in heat-treated mixtures EPS and DSC (% mass. ppm).
№ p/pDSK:UPUT-RA °Time, hAL
1131011,73
2231020,21
33310354 ppm
443104<1 ppm
5133011,06
62330236 ppm
733303,5<1 ppm
813501
92350212 ppm
1033503<1 ppm

As follows from the data placed in table 3, in mixtures with DSK with UPU complete conversion acetal is achieved in a predetermined temperature range when the ratio DSK:EPS, equal to 1:3-4, and time of heat treatment 3-4 hours.

The above results show the possibility of purification of phenol from acetol on the proposed method, applied industrial technological schemes of processing products, catalytic decomposition of the CCP.

The major difference of the proposed method is the fact that the separation of the phenol from the decomposition products of the CCP and its purification from organic impurities method heterotetramer rectification carried out on the complex (with a side selection) column, selecting the entire liquid side stream with a half-deaf plates in an exhaustive partition of the columns of the zone, where there is practically no water. This thread is directed in one unit, consisting of a section of the concentration of the Stripping column, adding to it as the separating agent is cumene. The residue from the Stripping column returns the column under half-deaf plate, below which the detailed section of the column must be not less than the 7,5 theoretical plates, and the distillate - acetazolamide fraction (DSC) is subjected to heat treatment at temperatures in the range of 310-350°With three options:

- directly, at the time of heat treatment up to 7 hours, adding heat mixture to the catalytic decomposition products of the CCP;

- or, for installations in which there is a unit of thermal splitting of high-boiling by-products of synthesis, DSC injected into the stream circulating from the cube distillation column separation of the products of thermal cleavage in a tube furnace and then to a distillation column (KP), with a ratio of DSK:KP 1:80-240, and processing time up to 20 minutes;

or, in relation to installations where there is no node splitting of high-boiling by-products of synthesis, DSK mix with kubovy product (UPU), the output from the column purification of phenolic fractions of high-boiling by-products of synthesis in the ratio of 1:3-4 when the processing time is 3-4 hours, adding heat mixture to the catalytic decomposition products of the CCP.

Compared with the known methods, including the prototype, the advantages of the proposed method are as follows: the proposed method does not require consumption of reagents and catalysts, in the cleaning process there is no waste water, no harmful emissions into the atmosphere, it is Ho who Osho is combined with the main industrial recycling schemes of decomposition products of the CCP, a simple technical methods and allows you to achieve a deep level of cleaning phenol from acerola almost without reducing the selectivity of the process as the phenol and the acetone.

Industrial feasibility and advantages of the proposed method are illustrated by the following examples.

Example 1.

In the example described the plot of the technological scheme (see diagram, figure 1) purification from acetal phenol raw output from the cube column heterotetramer cleaning 1.

Downward phenolic thread 2 is displayed with half-deaf plates 3, installed in an exhaustive partition of the column 1 in the zone where practically no water. The thread 2 is added to the cumene (stream 4), the mixture is fed to the cube of the Stripping column 5 efficiency of at least 15 theoretical plates. Pairs of columns 5 pass through the partial condenser 6, which establishes the irrigation of the column are condensed and cooled in the condenser of the refrigerator 7. The resulting distillate (stream 8) is directed to the heat treatment. The heat necessary to meet the heat balance of the column 5, is introduced via a heat exchanger 9, is installed in the cube column. Phenolic stream 10 from the cube column 5 arrives in column 1 under half-deaf plate, below which are the contact device with an efficiency of not less than 7.5 Theo is eticheskikh plates, which is discipline of acetol and cumene. From the cube columns 1 to finish cleaning displayed purified from acetal phenol-raw (stream 11).

Material flows above and their composition for a medium-sized plant capacity, working on the first version of the technological scheme of separation of the products of the catalytic decomposition of the CCP, i.e. when the maximum content of acerola presented in table 4.

Table 4.

Material flows and their composition
Components/streams24811
kg/h% (ppm)kg/h% (ppm)kg/h% (ppm)kg/h% (ppm)
Acetal50,30,13--50,2832,10,02(<1)
The cumene1,5(40)82,01*100,0to 83.553,10,01(<1)
AMC2,2(60)--1,120,7 1,08(43)

Continuation of table 4
Phenol and other impurities37500,099,86--25,114,125000,0<100,
Total:37552,5100,082,01100,0160,0100,025001,13100,0
*Cumene is served by an excess of up to 10% of the calculated and regulated by the flow analysis 11.

Example 2.

The distillate of the Stripping column (DSC), obtained as described in example 1 in the amount of 160 kg/h is subjected to heat treatment at a temperature of 310°, directing it to the heater, from which it enters thermostatic capacity-totravel. Possible design of the heater, where it is connected to the capacitance-doznavatelyam. The heat treatment are not less than 7 hours, while the amount of capacity-doserates taking into account the density of the medium will be about 1200 litres.

Termoobrabotannyj DSC, in which almost no acetal, attached to products catalyti the definition of decomposition of the CCP.

Example 3.

DSK, obtained as described in example 1 is subjected to heat treatment together with kubovy product (CP) thermal decomposition of high-boiling by-products of synthesis (EPS) according to the scheme shown in the diagram (figure 2).

EPS (stream 1) is fed to distillation column 2, CBM product (KP) partly derived from the system (stream 3), and paragraph (stream 4) is circulated through the tubular furnace 5 to the cube of the column 2. Stream 4 add (DSC) thread 6. The mixture flows 4 and 6 after the tube furnace 5 is kept in a temperature-controlled containers-doznavatel 7 so that at a temperature of 310°and the ratio KP:DSC, equal to 240, the total heat treatment time in the system: gotravel 7 - tube furnace 5 - column 2 was at least 20 minutes; at a temperature of 330°C, the ratio KP:DSC, equal to 160, and at a temperature of 350°and the ratio KP:DSC, equal to 80, not less than 15 minutes.

In compliance with the above conditions in the products after the vessel 7 (stream 8) and, respectively, in the distillate of the distillation column 2 (stream 9)is sent for further processing to recycling of valuable products, almost no acetal.

Material flows above for different conditions of heat treatment DSC are given in table 5.

Table 5.

Material flow and heat treatment conditions

DSC thermal cleavage of the UPU

Abbreviations: CC - frequency circulation, SP is the ratio of threads.
№ p/pFlow, kg/hConditions of heat treatment DSC
346T-RA °CC(4:3)JV (4:6)Time min
11280384001603101:301:24020
21280256001603301:201:16015
31280128001603501:101:8015

Example 4.

If the installation site thermal decomposition of high-boiling by-products of synthesis (EPS) distillate the Stripping column (DSC), obtained in the conditions of example 1, subjected to heat treatment in a mixture with CHD according to the scheme shown in the diagram (figure 3).

In the power of the column 1 is fed phenolic thread 2. On top of the column 1 is selected distillate, freed from the UPU, including 2-MBF (stream 3) from the Bottom of the column 1 display UPU, part of which is removed from the system (stream 4), and the other portion (stream 5) is mixed with DSC (stream 6) and sent for heat treatment in the heater 7 and, further, in the capacity-gotravel 8. The heat treatment is carried out at a temperature 310-350° & DSK:EPS=3-4 time and temperature effects 3-4 hours. Heat-treated product (stream 9), in which almost no acetal, attached to the decomposition products of the CCP.

Material flows above for different conditions of heat treatment DSC are shown in table 6.

Table 6.

Material flow and heat treatment conditions DSK mixed with UPU
№ p/pFlow, kg/hHeat treatment conditions
456T-RA °DSK:UPUTime, hour.
123606401603101:44
222004801603301:33,5
322004801603501:33

To advantage tvam of this method against direct heat treatment of the DSC is that what a remarkable number of IPOs undergoes thermal decomposition, i.e. the process of exhaustive conversion acetal combined with partial recycling of EPS, but the system remains "open", i.e. the accumulation of EPS in it not happening.

1. The method of purification of phenol from acerola during catalytic decomposition of gidroperekisi hydroperoxide (CHP) methods of rectification with sequential selection of the decomposition products of the CCP phenolic fraction, clean it from the high-boiling by-products of synthesis (EPS), thermal decomposition of EPS at elevated temperatures in the column, CBM product (KP) is circulated through the tubular furnace, the release of phenolic fractions of impurities of organic substances using heterotetramer rectification of water and purification of the thus obtained phenol raw from reactive trace contaminants, including acetal, using other methods, characterized in that acetol allocate the composition of the liquid side stream (BP) with half-deaf plates located in an exhaustive partition of the column heterotetramer distillation, BP add the cumene and send the power to the Stripping column as distillate from which the selected fraction of the azeotropic mixture of acetal and cumene (DSC), and the remainder is returned to discipline cumene and acetol the od half-deaf plate columns heterotetramer rectification, from the cube on which the finish cleanup from other reactive trace output phenol raw; fraction DSK subjected to heat treatment at a temperature of 310-350°With, directly, for a time up to 7 h, or high-boiling mixtures with waste production, preferably 3-4 hours when mixed with the high-boiling by-products of synthesis (EPS) in the ratio DSK:EPS=1:(3-4), or up to 20 minutes when mixed in the ratio 1:(80-240) circulating through the tube furnace kubovy product distillation column thermal splitting of high-boiling by-products of synthesis (KP).

2. The method according to claim 1, characterized in that the products of thermal treatment DSP directly or mixed with EPS attach to products of the catalytic decomposition of the CCP.

3. The method according to claim 1, characterized in that the heat treatment of DPS in a mixture with KP additional quantities of cumene, AMS and phenol allocated as part of a wide distillate fractions of the column thermal splitting of high-boiling products of synthesis, attached to the products of catalytic cleavage of the CCP directly or after separation from her low-boiling and high-boiling impurities.

4. The method according to claim 1, characterized in that the half-deaf plate, which is displayed PSU, have the detailed section of the column selection of the phenolic fraction of organic impurities which substances using heterotetramer distillation with water, in the area where the water content is minimal and below which are the contact device with an efficiency of not less than 7.5 theoretical plates.

5. The method according to claim 1, characterized in that PSU, which added to the cumene, guide cube in the Stripping column having an efficiency of at least 15 theoretical plates.

6. The method according to claim 5, wherein the hydroperoxide is added to BP with an excess of up to 10%greater than required for the formation of azeotropic mixtures with aatola, adjusting the flow of cumene according to the results of the analysis of phenol raw output from the cube column heterotetramer rectification.



 

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