RU2425020C1 - Method of producing isoprene - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method or producing isoprene via liquid-phase reaction of components of the raw materials - formaldehyde and, possibly, substances which are a source of formaldehyde, with tert-butanol, possibly isobutylene or substances which are a source of isobutylene, and possibly intermediate products of isoprene precursors, in the presence of a strong acid catalyst and water using molar excess of tert-butanol or isobutylene to formaldehyde or substances which are a source of formaldehyde, at temperature and pressure which facilitate transition of isoprene into the vapour phase followed by extraction thereof, which is carried out while feeding heat into the reaction zone of the reactor which is fitted with a mass-exchange cap, owing to circulation of the heated acid aqueous layer while ensuring temperature fall on the height of the reaction zone, characterised by that, the reactor has one or more extra series-arranged reaction zones fitted with a mass-exchange cap, raw material is fed into each zone through distribution devices, wherein heat is further fed into the additional zones by the vapour phase through the distribution devices from the previous reaction zone while maintaining temperature and pressure which facilitate transition of the main component of tert-butanol and isobutylene into vapour phase and temperature fall of 3-7°C on the height of each reaction zone.

EFFECT: reduced formation of by-products by more than 2,5 times with respect to output of isoprene while simultaneously reducing energy output of the process.

1 cl, 2 tbl, 2 ex, 2 dwg

Description

The invention relates to the field of basic organic and petrochemical synthesis, more specifically, to methods for the production of isoprene.

A known method of producing isoprene by liquid-phase interaction of formaldehyde and, possibly, a source of formaldehyde, with tert-butanol and possibly isobutene in the presence of a strong acid catalyst and water at elevated temperature and a molar excess of the supplied tert-butanol. The process is carried out in a vertical reaction zone connected from below to a boiler. The pressure in the reactor is maintained such that there is no condensation of isoprene. Moreover, most of the water, formaldehyde and a significant part of tert-butanol are in the liquid phase, forming an aqueous layer containing also a strong acidic catalyst. The heat supply in the known method is carried out through the boiler by evaporating the reaction mass coming from the bottom of the apparatus, and possibly circulating through the boiler part of the acidic water layer formed in the process, which, when the vapor and liquid move in the reaction zone, is taken up from the top and fed down. Isoprene is taken from the top of the apparatus as part of the steam stream, from which it is then isolated, see RU Patent 2203878, IPC6 C07C 11/18, 2003.

The disadvantages of this method are associated with the presence of the reaction mass in the tubes of the heat exchanger. Undesirable processes occur on hot pipes both from the point of view of selectivity of raw material transformations and corrosion, aggravated by exposure of pipe surfaces as a result of intense evolution of gaseous decomposition products and concentration of acid catalyst.

As follows from the operating experience of such installations, severe corrosion of the equipment metal and its resinification, especially on the hot surfaces of the heat exchanger tubes, proceeds at the liquid-gas phase boundary. In this case, corrosion salts can accumulate, which adversely affect the selectivity of the process. This necessitates the withdrawal of the catalyst solution for purification from metal salts (corrosion products) using sulfocationionites, which complicates the technology.

The closest in technical essence is the method of producing isoprene by liquid-phase interaction of formaldehyde and, possibly, substances that are the source of formaldehyde, with tert-butanol, possibly isobutylene or substances that are the source of isobutylene, and, possibly, intermediates - precursors of isoprene in the presence of a strong acid catalyst and water using a molar excess of tert-butanol or isobutylene to formaldehyde or substances that are the source of formaldehyde at a temperature and pressure, ensuring the transition of isoprene into the vapor phase with its subsequent release, and most of the water, formaldehyde and tert-butanol remains in the liquid phase, carried out with the heat being supplied to the reaction zone of the reactor equipped with a mass transfer nozzle, and including circulation and heating of the acid an aqueous layer in which heat is supplied only by circulating a heated acidic aqueous layer, while the layer is heated to a temperature below its boiling point, and the amount of circulating islogo aqueous layer should provide differential adjustment at the reaction zone temperature not exceeding 5 ° C, see. RU Patent 2341508, MPK7 C07C 11/18, C07C 1/20, C07C 2/86, 2008 g.

The disadvantages of this method include the following:

The organic layer and the aqueous-acidic layer are fed into the isoprene synthesis reactor in a single stream, which leads to overgrowth of the holes of the reactor distributor due to the contact of the reaction mass with the hot walls of the distributor; in this case, a vapor phase forms that impairs the distribution and the salt build-up on the walls of the device, and also the additional formation of high boiling point by-products.

Tert-butanol, located in a circulating acidic aqueous layer, decomposes upon heating in a heater to form gaseous isobutylene. It takes extra heat, which is then not replenished. However, the lack of tert-butanol in the liquid phase causes a large number of adverse reactions in the acidic aqueous layer with the participation of formaldehyde and increases the formation of high-boiling by-products.

The objective of the invention is to reduce the formation of high-boiling by-products while reducing the energy intensity of the isoprene production process.

The technical problem is solved by the method of producing isoprene by liquid-phase interaction of the components of the feedstock - formaldehyde and, possibly, substances that are the source of formaldehyde, with tert-butanol, possibly isobutylene or substances that are the source of isobutylene, and, possibly, intermediates - precursors of isoprene, in the presence of strong acid catalyst and water using a molar excess of tert-butanol or isobutylene to formaldehyde or substances that are the source of formaldehyde at a temperature and pressure, ensuring the transition of isoprene into the vapor phase with its subsequent release, carried out with the heat supplied to the reaction zone of the reactor equipped with a mass transfer nozzle due to the circulation of the heated acidic water layer with a temperature difference along the height of the reaction zone in which the reactor has one or more additional sequentially installed reaction zones equipped with a mass transfer nozzle, raw materials are supplied to each zone through distribution devices, while heat is additionally installed The renewed reaction zones are additionally supplied with the vapor phase through switchgears from the previous reaction zone with maintaining the temperature and pressure in them, which ensure the transfer of the main amount of tert-butanol and isobutylene to the vapor phase and the temperature difference in height of each reaction zone is 3-7 ° C.

The solution to the technical problem reduces the formation of by-products by more than 2.5 times in relation to the yield of isoprene with a simultaneous decrease in the energy intensity of the process of its production.

The present invention is illustrated in figures 1, 2.

According to figure 1, raw materials containing formaldehyde and, possibly, substances that are the source of formaldehyde, with tert-butanol, possibly isobutylene or substances that are the source of isobutylene, and possibly intermediates - precursors of isoprene, are fed through line 1 to at least two reaction zones of the R-4 reactor (Fig. 1 shows three zones Z-1, Z-2, Z-3) filled with mass transfer nozzle through distribution devices.

The acid catalyst solution (charge) through line 2 is fed to a T-3 recuperator and heated to a temperature of 150 ° C. Then, the heated catalyst mixture is fed through line 3 to the last reaction zone through a distribution device in which it interacts with the feed to form mainly isoprene. Isoprene under the reaction conditions passes into a vaporous state. In the reaction zones of the reactor, temperature and pressure are maintained to ensure that the bulk of tert-butanol and isobutylene are transferred to the vapor phase, which is sent to the subsequent reaction zone to heat the reaction mass. The acidic aqueous layer is fed to the previous reaction zones by level through overflow pipes, and from the first reaction zone Z-1, line 4 is taken from the reactor to the separator E-1. In addition, line 4 serves the majority of the catalyst charge from the T-3 recuperator via line 5 to withdraw metal salts from the acidic aqueous layer that are deposited in the vessel E-1. In the separator E-1, a large part of the high-boiling point insoluble products are separated from the acidic aqueous layer and sent to the T-5 heater through line 6 with the N-1 pump to heat it to a temperature below the boiling point (not higher than 170 ° C). Reducing the amount of tert-butanol in the liquid phase prevents contact of the reaction mass with the working surface of the T-5 heater, which minimizes the negative effects on the equipment described in the disadvantages of the analogue. The heated circulating acidic aqueous layer through line 7 is fed into the first reaction zone Z-1, while providing a temperature difference in the height of each reaction zone of 3-7 ° C. A circulating acidic aqueous layer is provided via line 8 to the last reaction zone to the catalyst charge input line 3. The insoluble high-boiling by-products and a smaller part of the acidic aqueous layer separated in the E-1 separator are fed through line 9 through a T-3 recuperator for processing.

From the top of the reactor through the KO-1 droplet eliminator, reaction products are taken in the form of a vapor phase along line 10, from which isoprene is subsequently isolated.

The heat recovery of the gaseous reaction products leaving the first reaction zone in the second and subsequent reaction zones while sparging them through the liquid layer of the reaction mass, as well as preventing the decomposition of tert-butanol in the T-5 heater, reduces the energy consumption of the isoprene production process; sectioning the reaction space while providing intensive mixing of the reacting streams due to bubbling, as well as an increase in the molar excess of tert-butanol along the height of the reactor, reduce the yield of by-products.

Figure 2 presents a schematic diagram of a process for the synthesis of isoprene from formaldehyde and isobutylene in an embodiment using C ₄ fractions of various origins with an intermediate synthesis of tert-butanol, dimethyldioxane, methylbutanediol, etc. These intermediates are synthesized in 3 reactors, then purified from high-boiling by-products, mixed and fed into the isoprene synthesis reactor P-4 in at least 2 reaction zones of the reactor.

For the synthesis of dimethyldioxane, an acidic aqueous layer from the E-1 extractor, to which formalin is added, is fed to the reactor R-1 through line 1. On line 2 in the reactor R-1 serves return isobutylene or isobutane-isobutylene fraction, or a mixture thereof from columns K-3, K-5. The synthesis products of dimethyldioxane from reactor R-1 are sent to a separator C-1 to separate part of the hydrocarbon layer from the acidic aqueous layer.

The acidic aqueous layer through line 3 is fed to the reactor R-2.

Through line 4, the hydrocarbon layer is fed through a T-1 heat exchanger to the E-2 extractor, where the layer is washed from carbonyl compounds. Water for washing the hydrocarbon layer in E-2 comes from line 5 from the K-4 column. Water containing carbonyl compounds is fed via line 6 to reactor P-2, and the washed hydrocarbon layer via line 7 is sent to sump C-2. The withdrawal of excess water from the system is also carried out along line 5.

Formaldehyde is exhausted from the acidic aqueous layer in reactor R-2; for this purpose, an additional amount of isobutylene or isobutane-isobutylene fraction or a mixture thereof from columns K-3, K-5, and also the acidic aqueous layer of reactor R are fed to the reactor through line 2 -1 mixed with water containing carbonyl compounds from E-1.

The reaction mass from the reactor R-2 through line 8 is fed through a heat exchanger T-2 to the sump C-2. The settled aqueous layer from C-2 along line 9 is sent for extraction into E-1. The hydrocarbon layer from the S-2 sump through line 10 is fed to the K-1 column to isolate the isobutane-isobutylene fraction, which is returned via line 11 to the E-1 extractor. The bottoms liquid of the K-1 column is mixed with the bottoms liquid of the K-3 column coming along line 12 and sent to the K-2 column to isolate isoprene precursors, as well as to remove high boiling point by-products. The mixture of isoprene precursors from the K-2 column through line 13 is sent to the isoprene synthesis reactor P-4.

In the extractor E-1, water-soluble high-boiling products are extracted with return isobutylene or isobutane-isobutylene fraction. The acidic water layer is fed through the line 14 to the extractor after the S-2 sump and the P-4 reactor, and the return isobutane-isobutylene fraction from K-1 is sent through line 11 to the extractor. It is possible to supply a return isobutane-isobutylene fraction from K-4 via line 15. A purified acidic aqueous layer is removed through a cube of the extractor, to which, if necessary, a mixture of phosphoric acid and hydroxyethylene diphosphonic acid is added via line 16, and then fed through a T-3 recuperator to the reactor R-4. The extract from E-1 is fed to the K-3 column to isolate the return isobutane-isobutylene fraction fed to line 2, a hydrocarbon layer is discharged through the cube of the column, which is fed through line 12 to the K-2 column to remove high-boiling by-products.

For the synthesis of tert-butanol, a fresh isobutane-isobutylene fraction and a water layer from the bottom of the K-4 column through line 5 are fed to the R-3 reactor via line 17. After synthesis, the reaction products are sent to the K-4 column to separate the water and recover isobutane-isobutylene fraction and tert-butanol fraction fed to line 13 to create an excess molar ratio of tert-butanol to dimethyldioxane. An aqueous solution of tert-butanol is also supplied to the K-4 column from the K-5 commercial isoprene recovery column through line 18.

Isoprene is synthesized in the R-4 reactor, for which an acidic aqueous layer is fed through line 19 to it, which is preheated in the T-3 recuperator with the cubic liquid of the reactor (line 20), and the reaction mixture of isoprene precursors is fed into the reactor via line 13. The acidic aqueous layer and the reaction mixture are fed into P-4 in at least two reaction zones of the reactor. Insoluble high-boiling by-products and a smaller part of the acidic water layer, which are cooled in a T-3 recuperator and sent for processing to the extractor, are removed from the high-boiling by-product separation tank installed on the circulation line of the acidic water layer in the reactor (not shown in the diagram of FIG. 2) E-1 along line 20. The synthesis products of isoprene from R-4 through a T-4 refrigerator are fed to the K-5 commercial isoprene recovery column. Isoprene and isobutylene are isolated in K-5 column, which, if necessary, is mixed with fresh isobutane-isobutylene fraction coming in line 21, and then fed to reactors R-1, R-2. An aqueous layer is removed from the cube of the K-5 column, which is fed through line 18 to the K-4 column to strengthen the tert-butanol solution and remove excess water.

The proposed scheme for the synthesis of isoprene eliminates the disadvantages of the prototype, in particular:

the presence of high-boiling by-products in the feed stream of the dimethyldioxane decomposition reactor, which leads to blocking of the interface, which negatively affects the selectivity of the process, increasing the formation of high-boiling by-products;

the difficulty of controlling the excess molar ratio of tert-butanol to dimethyldioxane due to the joint synthesis of intermediate products (tert-butanol, dimethyldioxane, etc.) in the same apparatus;

increased formation of high-boiling by-products at the stage of exhausting formaldehyde from the aqueous acid layer containing tert-butanol and high-boiling by-products with pure isobutylene in the second stage of the synthesis of intermediate products due to the absence of an inert solvent (for example, isobutane) and the increased solubility of dimethyldioxane in the aqueous layer associated with the presence in the reaction system of a large amount of tert-butanol.

Case Studies

Example 1

The synthesis of isoprene is carried out as described in figure 1. The reactor is a cylindrical apparatus with a diameter of 200 mm, divided into reaction zones by half-deaf plates and equipped with distribution devices. Each zone is filled with mass transfer nozzle.

Feedstock in an amount of 120.98 kg / h, containing dimethyldioxane, tert-butanol and water, is fed through line 1 to each of the three reaction zones of the reactor.

A catalyst charge of 47.76 kg / h, which is a 5% solution of phosphoric acid with the addition of hydroxyethylene diphosphonic acid in a ratio of 1: 0.3, is fed through line 2 to a T-3 recuperator and heated to a temperature of 150 ° C. Then part of it (18.53 kg / h) is fed through line 3 to the third reaction zone Z-3, in which the feedstock interacts with the catalyst charge in the mass transfer layer with the formation of mainly isoprene and isobutylene, as well as small amounts of high boiling point products. The additional heat necessary to maintain the temperature in the reaction zone is supplied by the vapor phase leaving the second reaction zone Z-2 and bubbling through the layer of liquid reaction mass. The temperature and pressure are maintained equal:

Temperature:

In the upper part of the reaction zone, 149 ° C

In the lower part of the reaction zone is 152 ° C

The pressure above the bubbling layer of 6.7 kgf / cm ²

Such operating conditions ensure the transition of the main amount of tert-butanol to the vapor phase.

Gaseous reaction products are removed from the rector through the integrated KO-1 droplet eliminator via line 10.

The acidic water layer through the overflow pipes at the level and the distribution device is sent to the second reaction zone Z-2, in which it interacts with the incoming raw materials in the layer of the mass transfer nozzle. The additional heat necessary to maintain the temperature in the reaction zone is supplied through the distribution plate to the vapor phase leaving the first reaction zone Z-1 and sparging through the layer of liquid reaction mass. The temperature and pressure are maintained equal:

Temperature:

In the upper part of the reaction zone 155 ° C In the lower part of the reaction zone 159 ° C Pressure over the bubble layer 6.83 kgf / cm ²

Such operating conditions ensure the transition of the main amount of tert-butanol to the vapor phase.

In the first reaction zone Z-1, an acidic aqueous layer is supplied from the second reaction zone Z-2, and the heat necessary to maintain the temperature in the reaction zone is supplied with a heated circulating acidic water layer along line 7. The temperature and pressure are maintained equal to:

Temperature:

In the upper part of the reaction zone 161 ° C In the lower part of the reaction zone 168 ° C Pressure over the bubble layer 7.06 kgf / cm ² Pressure at the bottom of the reactor 7.11 kgf / cm ²

Such operating conditions ensure the transition of the main amount of tert-butanol to the vapor phase.

The acidic aqueous layer is discharged from the reactor through line 4 to the vessel E-1, which also serves the majority of the catalyst charge through line 5 from the T-3 recuperator to remove metal salts from the acidic aqueous layer that are deposited in the vessel E-1. In addition, in the tank E-1, insoluble high-boiling by-products are separated from the acidic water layer, which, in a mixture with a smaller part of the acidic water layer, is removed through the T-3 recuperator for processing through line 9.

Purified from insoluble high-boiling by-products, the acidic aqueous layer is sent via line 6 using pump N-1 to the T-5 heater and heated to a temperature of 169 ° C, and fed through line 7 through a distributor to the lower part of the first reaction zone Z-1 below raw material distribution device.

The material balance of the synthesis of isoprene is presented in table 1.

From the presented table 1 it is seen that the relative yield of high-boiling products is 0.0574 kg / kg of isoprene (the ratio of the yield of high-boiling by-products to the yield of isoprene). Moreover, from the data presented in the description of the prototype material balance of the process carried out using similar raw materials, the relative yield of high-boiling products is 0.165 kg / kg of isoprene.

Table 1 Component entrance Exit steam liquid % kg / h % kg / h kg / h dimethyldioxane 23.95 14.20 0 0 0 tert-butanol 53.48 31.70 27.51 0 16.30 water 85.78 50.83 43,43 52,471 56.83 isoprene 0 0.00 23.44 0 13.89 isobutylene 0 0.00 15.02 0 8.90 high boiling point by-products 0 0.00 0 1.35 0.80 orthophosphoric acid 4.20 2.49 0 4.20 2.49 hydroxyethylene diphosphonic acid 1.33 0.79 0 1.33 0.79 109,391 59,351 Total 168.74 100.00 168.74 100.00

Example 2

The method of synthesis of isoprene is carried out according to the scheme shown in figure 2.

For the synthesis of dimethyldioxane, an acidic aqueous layer from the E-1 extractor 18.35 kg / h is fed to the R-1 reactor through line 1, formalin 33.554 kg / h (40 wt.% Aqueous solution) is added. On line 2, a mixture of the isobutane-isobutylene fraction from the K-3 column and the isobutylene from the K-5 column (28.663 kg / h) with a mass concentration of isobutylene of 50% is fed into the reactor R-1. The synthesis products of dimethyldioxane from reactor R-1 are sent to a separator C-1 to separate part of the hydrocarbon layer from the acidic aqueous layer.

The acidic aqueous layer through line 3 is fed to the reactor R-2.

The hydrocarbon layer in an amount of 38.829 kg / h (20.209 kg / h of dimethyldioxane; 0.177 kg / h of unsaturated alcohols; 1.533 kg / h of high-boiling by-products; 1.188 kg / h of tert-butanol, 0.087 kg / h of methylbutanediol, 14.332 kg / h of isobutane, 1.303 kg / h of isobutylene) through line 4 through a heat exchanger T-1 is fed to the extractor E-2, where the layer is washed from carbonyl compounds. Water for washing the hydrocarbon layer in E-2 comes from line 5 (2.912 kg / h) from the K-4 column. Water (4.365 kg / h) containing carbonyl compounds (unsaturated alcohols, tert-butanol, methylbutanediol) is fed via line 6 to reactor P-2, and the washed hydrocarbon layer (37.376 kg / h) containing dimethyldioxane and high boiling point by-products, line 7 is sent to the sump C-2. The withdrawal of excess water from the system is carried out through line 5 (23.922 kg / h).

Formaldehyde is depleted from the acidic aqueous layer in reactor R-2; for this purpose, an additional amount of a mixture of return isobutylene and fresh isobutane-isobutylene fraction (3.652 kg / h) from columns K-3 and K-5 with an isobutylene concentration is fed to the reactor through line 2 50 wt.%, As well as the acidic aqueous layer of the reactor R-1, mixed with water containing carbonyl compounds from E-2.

The reaction mass (49.756 kg / h) from the reactor R-2 through line 8 is fed through a heat exchanger T-2 to the sump C-2. The settled aqueous layer from C-2 (42.615 kg / h) along line 9 is sent for extraction into E-1. The hydrocarbon layer (44.518 kg / h) from the S-2 sump through line 10 is fed to the K-1 column to isolate the return isobutane-isobutylene fraction (17.627 kg / h), which is returned via line 11 to the E-1 extractor. The bottom liquid of the K-1 column is mixed with the bottom liquid of the K-3 column coming along line 12 and sent to the K-2 column to isolate isoprene precursors, as well as to remove high boiling point by-products (4.242 kg / h) as a bottom residue. The mixture of isoprene precursors from the K-2 column through line 13 in an amount of 25.626 kg / h (23.95 kg / h - dimethyldioxane, 1.676 kg / h - tert-butanol) is sent to the isoprene synthesis reactor P-4.

In the extractor E-1, water-soluble high-boiling products are extracted with the return isobutane-isobutylene fraction. Acid water layer is fed through the line 14 to the extractor after the S-2 sump and R-4 reactor (56.115 kg / h), and through the lines 11 (17.627 kg / h) and 15 (18.384 kg / h) the return isobutane-isobutylene fraction from K-1 and K-4. A purified acidic aqueous layer is removed through a cube of the extractor, and then fed through a T-3 recuperator to the P-4 reactor. The extract from E-1 is fed into the K-3 column to isolate the return isobutane-isobutylene fraction fed to line 2, a hydrocarbon layer is discharged through the cube of the column, which is fed through line 12 (2.978 kg / h) to the K-2 column to remove high-boiling by-products products.

For the synthesis of tert-butanol, a fresh isobutane-isobutylene fraction (36.769 kg / h 50 wt.% Isobutylene, 50% isobutane), as well as an aqueous layer from the cube of the K-4 column via line 5 (17.728 kg / h based on the molar ratio of isobutylene: water equal to 1: 3). After synthesis, the reaction products are sent to a K-4 column to separate water, isolate the return isobutane-isobutylene fraction (18.384 kg / h) and the tert-butanol fraction in the amount of 62.49 kg / h (51.804 kg / h of tert-butanol and 10.686 kg / h of water) supplied to line 13 to create an excess molar ratio of tert-butanol to dimethyldioxane. An aqueous solution of tert-butanol is also supplied to the K-4 column from the K-5 commercial isoprene recovery column through line 18 in an amount of 70.93 kg / h (27.51 kg / h of tert-butanol and 43.43 kg / h of water) .

Isoprene is synthesized in the R-4 reactor, for which purpose, through it, line 19 is fed with a catalyst charge (34.787 kg / h), which is preheated in a T-3 recuperator with bottoms of reactor liquid (line 20), and the reaction line is fed through line 13 to the reactor a mixture of isoprene precursors (88.116 kg / h). The acidic aqueous layer and the reaction mixture are fed into P-4 into the three reaction zones of the reactor. Insoluble high-boiling by-products and a smaller part of the acidic water layer (13.5 kg / h), which are cooled in a T-3 recuperator, are removed from the high-boiling by-product separation tank installed on the circulation line of the acidic water layer in the reactor (not shown in the diagram). sent for processing to the extractor E-1 through line 20. The products of the synthesis of isoprene from R-4 through a T-4 refrigerator is fed to the allocation column of commodity isoprene K-5. Isoprene (23.44 kg / h) and isobutylene (15.02 kg / h) are isolated in the K-5 column, and then fed to the reactors P-1, P-2. A water layer of 70.93 kg / h (27.51 kg / h of tert-butanol and 43.43 kg / h of water) is removed from the cube of K-5 column, which is fed through line 18 to K-4 column to strengthen the solution tert-butanol and withdrawal of excess water.

An example of a specific implementation demonstrates that the implemented scheme allows to reduce the content of high-boiling by-products in the feed streams and catalyst charge fed to the isoprene synthesis reactor, reducing raw material consumption rates, and also process all formaldehyde at the stage of dimethyldioxane synthesis, eliminating the need to concentrate an aqueous formalin solution.

Thus, as can be seen from examples of specific performance, the inventive method for producing isoprene can reduce the formation of high-boiling by-products in comparison with the prototype more than 2.5 times in relation to the yield of isoprene, as well as reduce the energy intensity of the process by recovering part of the heat leaving the reaction zones of gaseous reaction products and prevent decomposition of tert-butanol.

Claims (1)

A method of producing isoprene by liquid-phase interaction of the components of the feedstock - formaldehyde and possibly substances that are the source of formaldehyde, with tert-butanol, possibly isobutylene or substances that are the source of isobutylene, and possibly intermediates - isoprene precursors in the presence of a strong acid catalyst and water using a molar excess of tert -butanol or isobutylene to formaldehyde or substances that are the source of formaldehyde, at a temperature and pressure, providing transition isoprene into the vapor phase with its subsequent release, carried out with the heat being supplied to the reaction zone of the reactor equipped with a mass transfer nozzle due to the circulation of the heated acidic water layer with a temperature difference along the height of the reaction zone, characterized in that the reactor has one or more additional series installed reaction zones equipped with a mass transfer nozzle, raw materials are supplied to each zone through distribution devices, while heat is supplied to additionally installed reaction the zones are additionally supplied with the vapor phase through switchgears from the previous reaction zone with maintaining the temperature and pressure in them, ensuring the transition of the main amount of tert-butanol and isobutylene to the vapor phase and the temperature difference in height of each reaction zone is 3-7 ° C.

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