Isoprene production process

FIELD: industrial organic synthesis.

SUBSTANCE: first stage of the process comprises synthesis of 4,4-dimethyl-1,3-dioxan via isobutylene/formaldehyde condensation in presence of acid catalyst at 80-100ºC and pressure 1.6-2.0 MPa. Product and high-boiling by-product mixture are isolated from oil layer of reaction mixture. 4,4-Dimethyl-1,3-dioxan is then decomposed on calcium phosphate catalyst at 290-380ºC and pressure 0.12-0.16 MPa in presence of water steam. Contact gas is further processed to produce isoprene. High-boiling by-product mixture is distilled on vacuum rectification column to give distillate in amount 30-35% of the weight of feed. Distillate is passed to heterogeneous-phase catalytic decomposition into isoprene on ceramic filling at 400-450°C and pressure 0.12-0.16 MPa in presence of water steam supplied at (2-5):1 weight ratio to high-boiling by-product mixture. Contact gas obtained after decomposition of this mixture is processed jointly with contact gas obtained after decomposition of dimethyldioxan.

EFFECT: reduced amount of process waste and increased production of isoprene without increase in consumed raw material.

3 cl, 1 tbl, 4 ex

 

The invention relates to the petrochemical industry, more specifically to the field of production of monomers for polymer synthesis. More specifically the invention relates to the field of production of isoprene.

Isoprene is the monomer upon receipt composition of polyisoprene rubber, butyl rubber, isoprostanes polymers, which are used in the tire industry and in the manufacture of rubber products.

A known method of producing isoprene comprising a stage of liquid-phase synthesis of 4,4-dimethyl-1,3-dioxane (DMD) by the condensation of formaldehyde in aqueous solution with isobutylene in the form isobutylester fraction4in the presence as catalyst of sulfuric acid at a temperature of 85-95°C, pressure of 1.8-2.0 MPa, with separation of the reaction mass in water and oil layers. From the oil layer by distillation allocate DMD and a mixture of high-boiling by-products (WFP). The aqueous layer containing sulfuric acid and WFP, neutralized with alkali, and then evaporated. The residue after parki containing salt and WFP, is sent to waste water production. Received DMD further subjected to heterogeneous catalytic decomposition in the isoprene in the calcium phosphate catalyst at a temperature of 370-390°in the presence of water vapor. Contact the gas after decomposition of DME cooled, separated into water and hydrocarbon layers, from uglev the fat layer by distillation emit isoprene [OGO S. Kaliev and Idlis G.S. isoprene Production. - L.: Chemistry, 1973, p.48-63].

The disadvantages of this method are the availability of wastewater contaminated with salts and WFP, a significant amount of waste - runway, which is not used in the process.

A known method of producing isoprene comprising a stage of liquid-phase synthesis DMD condensation of formaldehyde in aqueous solution with isobutylene in the form isobutylester fraction4in the presence as catalyst of sulfuric acid at a temperature of 65-75°C, pressure of 1.0-1.2 MPa, with separation of the reaction mass in water and oil layers, with parcoy water layer, adding to the residue after parki source of an aqueous solution of formaldehyde and recycling the resulting mixture to a zone of condensation of formaldehyde with isobutylene, with the separation by distillation of the oil layer DMD and a mixture of the runway. Received DMD further subjected to heterogeneous catalytic decomposition in the isoprene in the phosphoric acid catalyst on the carrier at a temperature of 250-300°in the presence of water vapor. Contact the gas after decomposition of DME cooled, separated into water and hydrocarbon layers, from the hydrocarbon layer by distillation emit isoprene [OGO S. Kaliev and Idlis G.S. isoprene Production. - L.: Chemistry, 1973, p.64-70].

The disadvantages of this method are the formation of resins caused behold the Noah acid when Parke water layer, corrosion of the equipment in the presence of sulfuric acid, the complexity of the operation of the reactor decomposition DMD with the used catalyst, a significant amount of waste.

Closest to the claimed is known a method of producing isoprene comprising a stage of liquid-phase synthesis DMD condensation of formaldehyde in aqueous solution with isobutylene in the form isobutylester fraction4in the presence of oxalic acid as a catalyst at a temperature of 80-100°C, pressure of 1.6-2.0 MPa, with separation of the reaction mass in water and oil layers, with parcoy water layer, adding to the residue after parki source of an aqueous solution of formaldehyde and recycling the resulting mixture to a zone of condensation of formaldehyde with isobutylene, with the separation by distillation of the oil layer DMD and a mixture of the runway, including subsequent phase heterogeneous catalytic decomposition of DMD in the isoprene in the calcium phosphate catalyst at a temperature of 290-380°C, the pressure of 0.12 to 0.16 MPa in the presence of water vapor, cooling and separation of the contact of the gas after decomposition of the DMD on the water and hydrocarbon layers, emitting isoprene by distillation of the hydrocarbon layer [Kirpichnikov P.A., Beresnev V.V., Popova L. Album technological schemes the main production of the synthetic rubber industry. - L.:Chem which I 1986, p.36-53].

The disadvantages of the above method is the formation of significant amounts of waste that are not used in the process (number of runways is 440-460 kg per 1 t of the resulting isoprene), low production of isoprene from the feedstock - formaldehyde and isobutylene.

The objective of the proposed method is to reduce the amount of waste process for the production of isoprene and the increased production of isoprene from the same quantities of raw materials.

This task is solved by a method of producing isoprene comprising a stage of liquid-phase synthesis DMD condensation of formaldehyde in aqueous solution with isobutylene in the form isobutylester fraction4in the presence of acid catalyst at a temperature of 80-100°C, pressure of 1.6-2.0 MPa, with separation of the reaction mass in water and oil layers, with parcoy water layer, adding to the residue after parki source of an aqueous solution of formaldehyde and recycling the resulting mixture to a zone of condensation of formaldehyde with isobutylene, with the separation by distillation of the oil layer DMD and a mixture of the runway, including subsequent phase heterogeneous catalytic decomposition of DMD in the isoprene in the calcium phosphate catalyst at a temperature of 290-380°C, the pressure of 0.12 to 0.16 MPa in the presence of water vapor, with cooling and separation of the contact is about gas after decomposition of the DMD on the water and hydrocarbon layers, with the release of isoprene by distillation of the hydrocarbon layer, and the mixture runway, obtained at the stage of synthesis of DME, is distilled in a vacuum distillation column to obtain a distillate in the amount of 30-35 wt.% from power, the distillate is directed to heterogeneous catalytic decomposition of isoprene on the ceramic nozzle at a temperature of 400-450°C, the pressure of 0.12 to 0.16 MPa in the presence of water vapor, supplied in a mass ratio to the runway (2-5): 1, contact the gas after decomposition of the runway processed together with the contact gas after decomposition DMD.

As a variant of the proposed method lies in the fact that, as the acid catalyst for the synthesis DMD use oxalic acid, phosphoric acid or a mixture of these acids.

Also as a variant of the proposed method lies in the fact that the distillation WFP carried out under the following conditions:

the temperature of the top,°155-170

the temperature of the cube°190-200

pressure, MPa 0,015-0,03

the number of plates 22-28

reflux the number of 1-1,5

Distinctive features of the prototype characteristics of the proposed method are the following:

the mixture runway is distilled in a vacuum distillation column to obtain a distillate in the amount of 30-35 wt.% from power;

WFP contained in the distillate is directed to heterogeneous catalytic decomposition of isoprene on ceramic us is (DKE) at a temperature of 400-450° With the pressure of 0.12 to 0.16 MPa in the presence of water vapor, supplied in a mass ratio to the runway (2-5):1; contact gas after decomposition of the runway processed together with the contact gas after decomposition of the DMD. In the proposed method, the waste of the production of isoprene is VAT residue of the distillation column of the distillation mixture runway. Distilled portion of the mixture runway (30-35 wt.%) used in the process for production of isoprene.

Carrying out the distillation of the runway under vacuum (under reduced pressure) allows to reduce the operating temperature in the distillation column and to prevent resinification runway during distillation.

The increase in the proportion of distillate more than 35 wt.% leads to the increase of the content in the distillate most high molecular weight and high boiling components of the mixture runway - dioxane derivatives of alcohols, polyols, polymers. Of these compounds under these conditions, heterogeneous catalytic decomposition yields only coke and tar, which lead to rapid deactivation of the catalyst. Even small amounts of these compounds reduce the activity increases the coke formation and impair the catalyst for the decomposition of the runway. In connection with this decomposition directly the whole mass of the runway difficult to implement in practice, and in the proposed method, the share of distillate is not more than 35 wt.%.

A decline in the share distilla is and less than 30 wt.% distills not all components of the mixture runway, which can be decomposed with obtaining isoprene, which prevents to the greatest extent possible to reduce the amount of waste in the process.

Used as catalyst for the decomposition of the ceramic nozzle provides sufficient depth transformation of the runway and adequate yield of isoprene. Water vapor supplied into the zone of decomposition in the mass ratio to the runway (2-5):1, is used as a coolant to reduce coke formation, maintaining the stability of the catalytic activity and to enhance the performance of the catalyst. When the reduction ratio less than 2:1 reduced yield of isoprene and increases the coke formation. The increase in the ratio more than 5:1 is impractical due to increased energy consumption.

Decreasing the decomposition temperature of less than 400°With reduced depth transformation of the runway, decreases the yield of isoprene and reduces the production of isoprene.

With increasing temperature more than 450°With reduced yield of isoprene and increases the coke formation.

Association contact gas after decomposition of the runway contact with the gas after decomposition DMD is facilitated by carrying out contact as decomposition of DME, and the runway under the same pressure. United contact the gas is further processed together, which simplifies the process.

The proposed method is compared with the prototype provides is to reduce the amount of waste process to 280-295 kg per 1 t of isoprene, to increase the production of isoprene for 6 wt.% without increasing the consumption of raw materials.

Industrial application of the proposed method is illustrated by examples.

Example 1.

In the reactor block the synthesis of DME, consisting of five tubular reactors, serves isobutane-isobutilene fraction containing isobutylene to 47.8 wt.% with the speed of 37.3 t/h, and formaldehyde mixture, which is an aqueous solution containing 32.6 wt.% formaldehyde, 1.3 wt.% oxalic acid and 1.4 wt.% phosphoric acid, with a speed 53,1 t/h

In the reactor unit maintains the temperature of 98°C, a pressure of 1.9 MPa. Under these conditions, the reaction mixture is in a liquid state. Conversion of formaldehyde in the reactor unit is to 78.7 wt.%, the conversion of isobutylene to 79.3 wt.%.

Coming out of the reactor block of the reaction mass is separated into water and oil layers.

The aqueous layer was evaporated, the residue after parki mixed with the original aqueous solution of formaldehyde, which is a mixture of fresh and return formaldehyde solution, then the mixture in the reactor recycle unit as formaldehyde mixture.

The oil layer was washed with water, then subjected to distillation processing for selecting fusion products DMD.

At first (in the direction of flow of the oil layer) of distillation columns is distilled waste isobutane-isobutilene fraction, which is sent for further processing known methods.

Cubic liquid first column serves the second distillation column, where distilled trimethylquinoline fraction, which is recycled in the reactor block synthesis DMD.

Cubic liquid of the second column serves in the third distillation column, where distilled DMD in the amount of 20.8 t/H. the Residue after distillation DMD in number to 4.68 t/h is a runway.

Clubbed together DMD return DMD sent for heterogeneous catalytic decomposition of isoprene on calcium-phosphate catalyst. For the decomposition of DMD using two alternately operating sectional reactor. In reactors keep the temperature 360°C, a pressure of 0.12 MPa. In the reactor serves water vapor / mass ratio to the DMD of 1.8:1. Conversion DMD scores 83.3 wt.%.

The resulting contact gas after decomposition DMD served in the cooling and condensation, the resulting liquid is separated into water and hydrocarbon layers.

From the aqueous layer by distillation emit solution return of formaldehyde, which is sent to the reactor block synthesis DMD.

The hydrocarbon layer serves to install the isolation and purification of isoprene, where the rectification produce the target product is isoprene. Isoprene then used to obtain the composition of polyisoprene rubber.

The AOC is e isoprene, from hydrocarbon layer emit return isobutylene, which is attached to the fresh isobutane-isobutilene fraction, return DMD, which together with the main stream DMD served on the decomposition of isoprene, and the by-products formed by the decomposition of DME, which is sent for recycling.

The mixture runway, obtained at the stage of synthesis of DME, serves to distillation in a distillation column, where it supports the following modes:

the temperature of the top,°155-170

the temperature of the cube°190-200

pressure, MPa 0,015-0,03

the number of plates 22-28

reflux the number of 1-1,5

From the top of this column distillate in the amount of 1.41 t/H. the Proportion of distillate from the power supply is 30 wt.%. From the bottom of column output VAT residue in the number of 3.27 t/H. This VAT residue is a waste of the production of isoprene. VAT residue then disposed of by known methods.

The distillate distillation columns WFP sent for heterogeneous catalytic decomposition of isoprene. For the decomposition of runway use two alternately operating sectional reactor. The decomposition is performed on the ceramic nozzle placed on the shelves reactors. In reactors maintain a temperature of 400°C, a pressure of 0.12 MPa. In the reactor serves water vapor / mass ratio to runway 2:1.

Produced gas after contact razlozheny the runway unite with the contact gas after decomposition DMD and further processed together in the above manner.

The amount of isoprene produced in the process is 11.1 t/h, the amount of VAT residue after distillation of the runway (waste process) per 1 t of the resulting isoprene is 295 kg

Example 2.

The process is carried out analogously to example 1, but with the following differences.

Conversion of formaldehyde in the reactor block the synthesis of DMD is to 80.8 wt.%, the conversion of isobutylene 81,2 wt.%.

Develop DMD $ 21.3 t/h, the development of the runway at the stage of synthesis DMD is a 4.83 t/h

In reactors decomposition DMD support the pressure of 0.13 MPa. Conversion DMD is 82.8 wt.%.

The selection of distillate in the distillation column runway is of 1.55 t/h, the proportion of distillate 32 wt.% from the power output VAT residue 3.28 t/h

In reactors decomposition runway keep the temperature of 415°s With a pressure of 0.13 MPa. Water vapor is served in a mass ratio to the runway 3:1.

The amount of isoprene produced in the process is 11.4 t/h, the amount of VAT residue after distillation of the runway per 1 t of the resulting isoprene is 288 kg

Example 3.

The process is carried out analogously to example 1, but with the following differences.

Conversion of formaldehyde in the reactor block the synthesis of DMD is to 79.3 wt.%, the conversion of isobutylene 79,7 wt.%.

Production of DMD is to 20.9 t/h, the development of the runway at the stage of synthesis of DME is 4,74 t/h

In reactors decomposition DMD support the pressure of 0.14 MPa. Conversion DMD is 84,2 wt.%.

The selection of distillate in the distillation column runway is of 1.62 t/h, the proportion of distillate 34 wt.% from the power output VAT residue of 3.12 t/h

In reactors decomposition runway keep the temperature 430°C, a pressure of 0.14 MPa. Water vapor is served in a mass ratio to the runway 4:1.

The amount of isoprene produced in the process is to 11.2 t/h, the amount of VAT residue after distillation of the runway per 1 t of the resulting isoprene is 279 kg

Example 4.

The process is carried out analogously to example 1, but with the following differences.

Conversion of formaldehyde in the reactor block synthesis DMD is 81,4 wt.%, the conversion of isobutylene to 81.6 wt.%.

Develop DMD is 21.4 t/h, the development of the runway at the stage of synthesis of DME is 4,92 t/h

In reactors decomposition DMD support the pressure of 0.16 MPa. Conversion of DMD is to 83.7 wt.%.

The selection of distillate in the distillation column runway is 1,72 t/h, the proportion of distillate 35 wt.% from the power output VAT residue 3.2 t/h

In reactors decomposition runway keep the temperature to 450°C, pressure of 0.16 MPa. Water vapor is served in a mass ratio to the runway 5:1.

The amount of isoprene produced in the process is 11.5 t/h, the amount of VAT residue after distillation of the runway in calc is the 1 t obtained isoprene is 278 kg

The data of examples of the method are summarized in table.

As follows from the table, the proposed method allows to reduce the number of runway - waste process for the production of isoprene to 280-295 kg per 1 t derived isoprene. In addition, compared with the known method, the proposed method can improve the yield of isoprene for 6 wt.% without increasing the consumption of raw materials.

Table
The indicators of the process of obtaining isopreneExample 1Example 2Example 3Example 4
1. Submission formaldehyde charge on the synthesis of DME, t/h53,153,153,153,1
2. The concentration of formaldehyde in the mixture, wt.%:    
formaldehyde32,632,632,632,6
oxalic acid1,31,31,31,3
phosphoric acid1,41,41,41,4
3. Feed isobutane-isobutilene fraction

on the synthesis of DME, t/h
     
37,337,337,337,3
4. The concentration of isobutylene in the isobutane-isobutilene fraction, wt.%47,847,847,847,8
5. The temperature in the reactor synthesis DME, °98989898
6. The pressure in the reactor synthesis DMD, MPa1,91,91,91,9
7. Conversion of formaldehyde, wt.%78,780,879,381,4
8. The conversion of isobutylene, wt.%79,381,279,781,6
9. Production of DME, t/h20,821,320,921,4
10. The development of the runway at the stage of synthesis of DME, t/hto 4.68a 4.834,744,92
11. The temperature in the reactor decay DMD,°360360360360
12. The pressure in the reactor decay DMD, MPa0,120,130,140,16

continuation of the table
13. Conversion of DME, wt.%83,382,884,283,7
14. The selection of distillate in the distillation column runway for decomposition, t/h1,411,551,621,72
15. The proportion of distillate from the power supply to the distillation column runway, wt.%30323435
16. Output VAT residue in the distillation column runway, t/hwith 3.273,283,123,2
17. The temperature in the reactor decay runway°400415430450
18. The pressure in the reactor for the decomposition of the runway, MPa0,120,130,140,16
19. The mass ratio of water vapor to the runway at the entrance to the reactor decay runway2:13:14:15:1
20. Production of isoprene, t/h11,111,411,211,5
21. The number of VAT residue after distillation of the runway (waste process) per 1 t of the resulting isoprene, kg295288279278

1. The method of obtaining and what Oprea, including the stage of liquid-phase synthesis of 4,4-dimethyl-1,3-dioxane condensation of formaldehyde in aqueous solution with isobutylene in the form isobutylester fraction C4in the presence of acid catalyst at a temperature of 80-100°C, pressure of 1.6-2.0 MPa with the separation of the reaction mass in water and oil layers, with parcoy water layer, adding to the residue after parki source of an aqueous solution of formaldehyde and recycling the resulting mixture to a zone of condensation of formaldehyde with isobutylene, with the separation by distillation of the oil layer 4,4-dimethyl-1,3-dioxane and a mixture of high-boiling by-products, including the next phase heterogeneous catalytic decomposition of 4,4-dimethyl-1,3-dioxane in the isoprene in the calcium phosphate catalyst at a temperature of 290-380°With, the pressure of 0.12 to 0.16 MPa in the presence of water vapor, cooling and separation of the contact of the gas after decomposition of 4,4-dimethyl-1,3-dioxane, water and hydrocarbon layers, emitting isoprene by distillation of the hydrocarbon layer, characterized in that the mixture of high-boiling by-products obtained at the stage of synthesis of 4,4-dimethyl-1,3-dioxane, is distilled in a vacuum distillation column to obtain a distillate in the amount of 30-35 wt.% from power, the distillate is directed to heterogeneous catalytic decomposition of isoprene on to ramitelli the nozzle at a temperature of 400-450° With the pressure of 0.12 to 0.16 MPa in the presence of water vapor supplied to the mass ratio of the high-boiling by-products (2-5):1, contact the gas after decomposition of high-boiling by-products are processed together with the contact gas after decomposition of 4,4-dimethyl-1,3-dioxane.

2. The method according to claim 1, characterized in that as the acid catalyst for the synthesis of 4,4-dimethyl-1,3-dioxane use oxalic acid, phosphoric acid or a mixture of these acids.

3. The method according to claim 1, characterized in that the distillation of high-boiling by-products is conducted under the following conditions:

The temperature of the top, °155-170

The temperature of the cube °190-200

Pressure, MPa 0,015-0,03

The number of plates 22-28

Reflux the number of 1-1,5



 

Same patents:

FIELD: industrial organic synthesis.

SUBSTANCE: first stage of the process comprises synthesis of 4,4-dimethyl-1,3-dioxan via isobutylene/formaldehyde condensation in presence of acid catalyst at 80-100ºC and pressure 1.6-2.0 MPa. Product and high-boiling by-product mixture are isolated from oil layer of reaction mixture. 4,4-Dimethyl-1,3-dioxan is then decomposed on calcium phosphate catalyst at 290-380°C and pressure 0.12-0.16 MPa in presence of water steam. Contact gas is further processed to produce isoprene. High-boiling by-product mixture is distilled on two in series connected vacuum rectification columns. On the first column, 60-70% of distillate is recovered based on the weight of feed. Second distillation on the second column gives second distillate (75-90%) and bottom product, which is recycled into 4,4-dimethyl-1,3-dioxan synthesis zone. Second-column distillate is decomposed into isoprene on ceramic filling at 400-450°C and pressure 0.12-0.16 MPa in presence of water steam supplied at (2-5):1 weight ratio to high-boiling by-product mixture. Contact gas obtained after decomposition of this mixture is processed jointly with contact gas obtained after decomposition of dimethyldioxan.

EFFECT: reduced amount of process waste and increased production of isoprene without increase in consumed raw material.

3 cl, 1 dwg, 1 tbl, 4 ex

FIELD: hydrogenation-dehydrogenation catalysts.

SUBSTANCE: invention relates to catalysts used in isoamylenes-into-isoprene dehydrogenation process and contains, wt %: iron oxide 62-75.4, potassium carbonate 12-21.5, chromium oxide 1-3, potassium hydroxide 0.5-2.5, sulfur 0.1-2.0, ammonium nitrate 0.1-2.0, silicon dioxide 1-5, calcium carbonate 1-5, and cerium nitrate 1-3.

EFFECT: increased mechanical strength, resistance to saturated steam and moisture, and stability during long-time operation.

3 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber and butyl rubber used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan on calcium phosphate catalyst comprising synthesis of 4,4-dimethyl-1,3-dioxan by interaction of isobutylene-containing C4 fraction with aqueous formaldehyde solution in presence of acid catalyst to form reaction medium composed of oil and water layers followed by separation of oil layer into unreacted C4-hydrocarbons and 4,4-dimethyl-1,3-dioxan by rectification leaving bottom residue containing dioxan alcohols (high-boiling dioxan alcohols to be processed into additional product), separation of water layer, condensation of contact gas, and recovery of desired isoprene. Low-boiling part of hydrocarbons distilled off in processing of bottom residue of 4,4-dimethyl-1,3-dioxan rectification is separated and thus obtained lower product is discharged as a mixture of high-boiling dioxan alcohols, which constitute additional desired product, whereas upper product is combined with formaldehyde-containing blend fed into 4,4-dimethyl-1,3-dioxan synthesis zone. Acid catalyst utilized in synthesis of 4,4-dimethyl-1,3-dioxan is mixture of oxalic and phosphoric acids at weight ratio between 2:1 and 1:1, whereas summary concentration of acids in formaldehyde-containing blend is maintained between 1.5 and 2.5 wt %. Remaining high-boiling fraction of hydrocarbons taken off in processing of bottom residue of 4,4-dimethyl-1,3-dioxan rectification, which are mixture of heavy residue and high-boiling alcohols, are taken off in the form of by-product.

EFFECT: enhanced isoprene production efficiency and reduced corrosion of technique, clogging with salts and tars, produced useful dioxan alcohols, and reduced specific consumption of raw materials.

1 dwg, 3 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber, butyl rubber, and isoprene-containing polymers used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan on calcium phosphate catalyst comprising synthesis of 4,4-dimethyl-1,3-dioxan by interaction of isobutylene-containing C4 fraction with formaldehyde-containing blend based on methanol-free formalin obtained by oxidation of methanol followed by rectification of formalin, accomplished at elevated temperature and pressure in presence of acid catalyst followed by separation of reaction medium into oil and water layers including extraction of organic products from water layer, isolation of 4,4-dimethyl-1,3-dioxan, unreacted C4-hydrocarbons, and high-boiling by-products from oil layer, condensation of 4,4-dimethyl-1,3-dioxan decomposition contact gas and isolating from condensate isoprene, unreacted 4,4-dimethyl-1,3-dioxan, recycling isobutylene and formaldehyde-containing water, performing also withdrawal of extracted water layer to be vacuum evaporated followed by sending evaporated water layer to preparation of formaldehyde-containing blend. Evaporation of extracted water layer containing acid catalyst is carried out at temperature of boiler wall in rectification column 80-105°C and residual pressure 0.015-0.025 MPa. Distillate is mixed with above-indicated formaldehyde-containing water and resulting mixture is subjected to two-step concentration of formaldehyde. Second-step distillate, namely recycle methanol, is sent to oxidation zone. Bottom residues of the second step of formaldehyde concentration and those of the extracted water layer evaporation are combined with methanol-free formaldehyde and acid catalyst continuously supplied as replenishment, after which used as formaldehyde-containing blend in the 4,4-dimethyl-1,3-dioxan synthesis. Concentration of acid catalyst is maintained between 1.60 and 1.75 wt %.

EFFECT: increased productivity and reduced material and power consumption.

2 cl, 1 dwg, 5 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber and butyl rubber used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan in reactors caused by interaction of isobutylene-containing C4 fraction with aqueous formaldehyde solution (prepared by oxidation of methanol) at elevated temperature and pressure in presence of acid catalyst to form reaction medium composed of oil and water layers followed by separation of oil layer into unreacted C4-hydrocarbons and 4,4-dimethyl-1,3-dioxan by rectification leaving bottom residue containing dioxan alcohols (high-boiling by-products to be processed into additional product), separation of water layer, condensation of 4,4-dimethyl-1,3-dioxan decomposition contact gas, and recovery of desired isoprene by rectification. Bottom residue is processed at residual pressure 0.002-0.010 MPa, elevated reflux ratio equal to 2.0-5.0, and continuous circulation of bottom fluid under lower plate of rectification column at weight ratio of circulating bottom fluid as additional product to bottom residue of 4,4-dimethyl-1,3-dioxan rectification equal to 20-35. Column distillate - low-boiling by-products are sent to 4,4-dimethyl-1,3-dioxan synthesis reactors or subjected to catalytic decomposition, separately or jointly with 4,4-dimethyl-1,3-dioxan.

EFFECT: enhanced isoprene production efficiency and reduced specific consumption of raw materials.

1 dwg, 5 ex

The invention relates to devices used for one-step synthesis of isoprene from isobutylene

The invention relates to the field of petrochemicals and can be used in the production of isoprene monomer to synthetic rubber

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber and butyl rubber used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan in reactors caused by interaction of isobutylene-containing C4 fraction with aqueous formaldehyde solution (prepared by oxidation of methanol) at elevated temperature and pressure in presence of acid catalyst to form reaction medium composed of oil and water layers followed by separation of oil layer into unreacted C4-hydrocarbons and 4,4-dimethyl-1,3-dioxan by rectification leaving bottom residue containing dioxan alcohols (high-boiling by-products to be processed into additional product), separation of water layer, condensation of 4,4-dimethyl-1,3-dioxan decomposition contact gas, and recovery of desired isoprene by rectification. Bottom residue is processed at residual pressure 0.002-0.010 MPa, elevated reflux ratio equal to 2.0-5.0, and continuous circulation of bottom fluid under lower plate of rectification column at weight ratio of circulating bottom fluid as additional product to bottom residue of 4,4-dimethyl-1,3-dioxan rectification equal to 20-35. Column distillate - low-boiling by-products are sent to 4,4-dimethyl-1,3-dioxan synthesis reactors or subjected to catalytic decomposition, separately or jointly with 4,4-dimethyl-1,3-dioxan.

EFFECT: enhanced isoprene production efficiency and reduced specific consumption of raw materials.

1 dwg, 5 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber, butyl rubber, and isoprene-containing polymers used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan on calcium phosphate catalyst comprising synthesis of 4,4-dimethyl-1,3-dioxan by interaction of isobutylene-containing C4 fraction with formaldehyde-containing blend based on methanol-free formalin obtained by oxidation of methanol followed by rectification of formalin, accomplished at elevated temperature and pressure in presence of acid catalyst followed by separation of reaction medium into oil and water layers including extraction of organic products from water layer, isolation of 4,4-dimethyl-1,3-dioxan, unreacted C4-hydrocarbons, and high-boiling by-products from oil layer, condensation of 4,4-dimethyl-1,3-dioxan decomposition contact gas and isolating from condensate isoprene, unreacted 4,4-dimethyl-1,3-dioxan, recycling isobutylene and formaldehyde-containing water, performing also withdrawal of extracted water layer to be vacuum evaporated followed by sending evaporated water layer to preparation of formaldehyde-containing blend. Evaporation of extracted water layer containing acid catalyst is carried out at temperature of boiler wall in rectification column 80-105°C and residual pressure 0.015-0.025 MPa. Distillate is mixed with above-indicated formaldehyde-containing water and resulting mixture is subjected to two-step concentration of formaldehyde. Second-step distillate, namely recycle methanol, is sent to oxidation zone. Bottom residues of the second step of formaldehyde concentration and those of the extracted water layer evaporation are combined with methanol-free formaldehyde and acid catalyst continuously supplied as replenishment, after which used as formaldehyde-containing blend in the 4,4-dimethyl-1,3-dioxan synthesis. Concentration of acid catalyst is maintained between 1.60 and 1.75 wt %.

EFFECT: increased productivity and reduced material and power consumption.

2 cl, 1 dwg, 5 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of isoprene for use in synthesis of isoprene rubber and butyl rubber used in tire industry and manufacture of general mechanical rubber goods. In the method of invention, isoprene is obtained by decomposition of 4,4-dimethyl-1,3-dioxan on calcium phosphate catalyst comprising synthesis of 4,4-dimethyl-1,3-dioxan by interaction of isobutylene-containing C4 fraction with aqueous formaldehyde solution in presence of acid catalyst to form reaction medium composed of oil and water layers followed by separation of oil layer into unreacted C4-hydrocarbons and 4,4-dimethyl-1,3-dioxan by rectification leaving bottom residue containing dioxan alcohols (high-boiling dioxan alcohols to be processed into additional product), separation of water layer, condensation of contact gas, and recovery of desired isoprene. Low-boiling part of hydrocarbons distilled off in processing of bottom residue of 4,4-dimethyl-1,3-dioxan rectification is separated and thus obtained lower product is discharged as a mixture of high-boiling dioxan alcohols, which constitute additional desired product, whereas upper product is combined with formaldehyde-containing blend fed into 4,4-dimethyl-1,3-dioxan synthesis zone. Acid catalyst utilized in synthesis of 4,4-dimethyl-1,3-dioxan is mixture of oxalic and phosphoric acids at weight ratio between 2:1 and 1:1, whereas summary concentration of acids in formaldehyde-containing blend is maintained between 1.5 and 2.5 wt %. Remaining high-boiling fraction of hydrocarbons taken off in processing of bottom residue of 4,4-dimethyl-1,3-dioxan rectification, which are mixture of heavy residue and high-boiling alcohols, are taken off in the form of by-product.

EFFECT: enhanced isoprene production efficiency and reduced corrosion of technique, clogging with salts and tars, produced useful dioxan alcohols, and reduced specific consumption of raw materials.

1 dwg, 3 ex

FIELD: hydrogenation-dehydrogenation catalysts.

SUBSTANCE: invention relates to catalysts used in isoamylenes-into-isoprene dehydrogenation process and contains, wt %: iron oxide 62-75.4, potassium carbonate 12-21.5, chromium oxide 1-3, potassium hydroxide 0.5-2.5, sulfur 0.1-2.0, ammonium nitrate 0.1-2.0, silicon dioxide 1-5, calcium carbonate 1-5, and cerium nitrate 1-3.

EFFECT: increased mechanical strength, resistance to saturated steam and moisture, and stability during long-time operation.

3 ex

FIELD: industrial organic synthesis.

SUBSTANCE: first stage of the process comprises synthesis of 4,4-dimethyl-1,3-dioxan via isobutylene/formaldehyde condensation in presence of acid catalyst at 80-100ºC and pressure 1.6-2.0 MPa. Product and high-boiling by-product mixture are isolated from oil layer of reaction mixture. 4,4-Dimethyl-1,3-dioxan is then decomposed on calcium phosphate catalyst at 290-380°C and pressure 0.12-0.16 MPa in presence of water steam. Contact gas is further processed to produce isoprene. High-boiling by-product mixture is distilled on two in series connected vacuum rectification columns. On the first column, 60-70% of distillate is recovered based on the weight of feed. Second distillation on the second column gives second distillate (75-90%) and bottom product, which is recycled into 4,4-dimethyl-1,3-dioxan synthesis zone. Second-column distillate is decomposed into isoprene on ceramic filling at 400-450°C and pressure 0.12-0.16 MPa in presence of water steam supplied at (2-5):1 weight ratio to high-boiling by-product mixture. Contact gas obtained after decomposition of this mixture is processed jointly with contact gas obtained after decomposition of dimethyldioxan.

EFFECT: reduced amount of process waste and increased production of isoprene without increase in consumed raw material.

3 cl, 1 dwg, 1 tbl, 4 ex

FIELD: industrial organic synthesis.

SUBSTANCE: first stage of the process comprises synthesis of 4,4-dimethyl-1,3-dioxan via isobutylene/formaldehyde condensation in presence of acid catalyst at 80-100ºC and pressure 1.6-2.0 MPa. Product and high-boiling by-product mixture are isolated from oil layer of reaction mixture. 4,4-Dimethyl-1,3-dioxan is then decomposed on calcium phosphate catalyst at 290-380ºC and pressure 0.12-0.16 MPa in presence of water steam. Contact gas is further processed to produce isoprene. High-boiling by-product mixture is distilled on vacuum rectification column to give distillate in amount 30-35% of the weight of feed. Distillate is passed to heterogeneous-phase catalytic decomposition into isoprene on ceramic filling at 400-450°C and pressure 0.12-0.16 MPa in presence of water steam supplied at (2-5):1 weight ratio to high-boiling by-product mixture. Contact gas obtained after decomposition of this mixture is processed jointly with contact gas obtained after decomposition of dimethyldioxan.

EFFECT: reduced amount of process waste and increased production of isoprene without increase in consumed raw material.

3 cl, 1 tbl, 4 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for preparing isoprene that is a monomer in synthesis of polyisoprene, butyl rubber, isoprene-containing polymers used in tire industry and rubber-technical articles and can be used in petrochemical industry. Proposed method for preparing isoprene involves decomposition of 4,4-dimethyl-1,3-dioxane on calcium-phosphate catalyst and involves synthesis of 4,4-dimethyl-1,3-dioxane by interaction of isobutylene-containing C4-fraction with formaldehyde aqueous solution in the presence of acid catalyst to form reaction mass consisting of oily and aqueous layers. Then oily layer is separated to isolate unreacted C4-hydrocarbons and 4,4-dimethyl-1,3-dioxane by rectification and removal of vat residue containing high-boiling dioxane alcohols and other by-side products, separation by rectification and isolation of floating reagent-oxal and absorbent that involves also processing aqueous layer and the following isolation the main product - isoprene from hydrocarbon condensate. Vat residue after rectification of 4,4-dimethyl-1,3-dioxane is separated by rectification for two stages carried out successively in in-line connected columns and bottom product from the first stage - heavy residue with ignition point 130-155°C is removed as floating reagent-oxal. Upper product from the first stage is fed for processing to the second stage and upper product from the second stage - light-boiling part of high-boiling by-side products is fed for decomposition completely on calcium-phosphate catalysts separately or in common with 4,4-dimethyl-1,3-dioxane. Bottom product from the second stage is fed to the synthesis process of 4,4-dimethyl-1,3-dioxane as recycle. Upper product from the second stage in processing by rectification of vat residue of rectification of 4,4-dimethyl-1,3-dioxane is fed for preparing absorbent only in case of stopping decomposition reactors with high-boiling by-side products or reactors wherein 4,4-dimethyl-1,3-dioxane is decomposed. In stopping reactors with decomposition of high-boiling by-side products upper product of the second stage is removed as recycle to synthesis of 4,4-dimethyl-1,3-dioxane and as absorbent component removing in the amount 25-35% of mass of vat residue of rectification of 4,4-dimethyl-1,3-dioxane feeding to the first stage. In stopping reactors with decomposition of high-boiling products and if necessary a mixture of dioxane alcohols, in particular, hydroxyisopropyl-4,4-dioxane-1,3, methyl-4-hydroxyethyldioxane-1,3 and dimethyl-4,4-hydroxymethyl-5-dioxane-1,3 are removed additionally as a bottom product of the second stage. Invention provides enhancing effectiveness in using waste - high-boiling by-side products, preparing additional amount of isoprene from them and enhancing regulation of the process.

EFFECT: improved preparing method.

4 cl, 1 dwg, 6 ex

FIELD: petrochemical processes.

SUBSTANCE: tert-butyl alcohol, 4,4-dimethyl-1,3-dioxan and/or formaldehyde are fed into reaction zone in the form of homogenous mixture with recycled aqueous solution of acid catalyst, which mixture is preliminarily prepared in a separate apparatus at heated to 80-90°C and said aqueous acid solution freed of organics is preliminarily passed through cationite at volume flow rate 15-20 h-1. Process is conducted at elevated temperature and pressure exceeding pressure of water steam at this temperature, and at molar excess of tert-butyl alcohol relative to summary amount of formaldehyde in hollow apparatus mounted coaxially over shell-and-tube heat exchanger and provided with circulation pipe connecting top part of hollow apparatus to bottom part of shell-and-tube heat exchanger, diameter of this pipe being at least three times lass than that of hollow reactor. Circulating factor at least 100 h-1 is achieved with the aid of pump installed in feed supply line into bottom part of hollow apparatus. Reaction products and part of aqueous acid solution are removed from the top of hollow apparatus in one stream passed into separator.

EFFECT: simplified technology and increased yield of isoprene.

1 dwg, 3 tbl, 3 ex

FIELD: industrial organic synthesis and petrochemistry.

SUBSTANCE: isoprene is produced via reaction of tert-butyl alcohol with 4,4-dimethyl-1,3-dioxane and/or formaldehyde in one reaction zone, namely upright hollow apparatus with, disposed inside it, shell-and-tube heat exchanger dividing apparatus space into top and bottom parts. Reaction mixture circulates through tubes of this apparatus in liquid-phase mode in presence of aqueous acid catalyst solution, at elevated temperature and pressure exceeding water vapor pressure at the same temperature, using molar excess of tert-butyl alcohol relative to summary formaldehyde equivalent. Reaction products are continuously withdrawn from reaction zone and subjected to condensation. Water phase is extracted with condensed distillate to remove organics, wherefrom isobutylene is recovered and sent to production of tert-butyl alcohol. Hollow apparatus is provided with one or two external circulation tubes connecting top and bottom spaces of apparatus, volume ratio of which is (2-2.5):1, respectively. Diameter of external tubes is at least fivefold greater that that of heat exchanger tubes. Feed is supplied to reaction zone in the form of homogenous mixture, preliminarily prepared in a separate apparatus and preheated to 80-90°C, together with recycle aqueous catalyst solution, the latter having been preliminarily freed of organics and passed at flow rate 15-20 h-1 through cationite. Process is carried out at circulation rate at least 100 h-1.

EFFECT: simplified technology and increased yield of isoprene.

1 dwg, 2 tbl, 2 ex

FIELD: industrial organic synthesis and petrochemistry.

SUBSTANCE: isoamylenes are subjected to dehydrogenation in presence of overheated water steam and catalyst containing, wt %: potassium oxide and/or lithium oxide, and/or rubidium oxide, and/or cesium oxide, 10-40; cerium(IV) oxide 2-20; magnesium oxide 2-10; calcium carbonate 2-10; sulfur 0.2-5; and ferric oxide - the rest.

EFFECT: increased isoamylene dehydrogenation degree due to increased catalyst selectivity with regard to isoprene and prolonged service time of catalyst.

2 tbl, 22 ex

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