A method of producing isoprene

 

(57) Abstract:

A method of producing isoprene by reacting the isobutene contained in the hydrocarbons of C4with water in the presence of an acid catalyst, followed by separation of the stream containing predominantly formed tert. butanol, interaction obtained tert.butanol with formaldehyde in the presence of an acid catalyst at elevated temperature and pressure with the separation of the reaction mass in water and the oil layer and the release of isoprene from the oil layer by distillation and washing, followed by purification of isoprene from oxygen-containing compounds by extractive distillation using as a selective solvent of the obtained tert.butanol followed by desorption of oxygen-containing compounds from saturated solvent and the flow of desorbed solvent to interact with formaldehyde. It is preferable to use not a complete desorption of oxygen-containing compounds, and to have the degree of desorption of 30-95%. Selected isoprene sent to the treatment plant may contain 2.0 to 20 wt.% tert.butanol. In one embodiment, the proposed method obtained tert.butanol containing up to 15 Otok from the top of the extractive distillation column, then separate the formed bottom layer, mainly containing water and an upper layer containing predominantly isoprene and tert.butanol, send in the upper part of the extractive distillation column. 3 C. p. F.-ly, 5 PL.

The invention relates to petrochemistry, and in particular to methods for producing isoprene from isobutylene and formaldehyde.

Isoprene is widely used as a monomer for the manufacture of rubber on properties close to natural as well as in organic synthesis.

A known method of producing isoprene from isobutylene contained in C4fractions of pyrolysis or dehydrogenation of isobutane, and formaldehyde two-stage method with the formation of the first stage in the presence of an acid catalyst intermediate 4,4-dimethyldioxanes-1,3 (DMD), released from the reaction mass, decomposition DMD to isoprene in the second stage in the gas phase in the presence of an acid catalyst, followed by separation of the resulting isoprene from the reaction mass [1] the catalyst for the first stage serve acids (sulfuric, phosphoric, oxalic acid), the catalyst of the second stage can serve as phosphoric acid on aluminum silicate, aluminum oxide (25% oxide Kremnica energy, the complexity of the technological scheme, a large number of sewage.

Closest to the proposed method is a method of producing isoprene by reacting the isobutene contained in the hydrocarbons of C4with water in the presence of sulfuric acid, followed by separation of the resulting tert.butanol, interaction allocated tert.butanol with formaldehyde in the presence of acid catalyst in one stage at elevated temperature and pressure with the separation of the reaction mass in water and the oil layer and the release of isoprene from the oil layer by distillation and washing [2] For selected isoprene meet the quality requirements of the stereoregular polymerization, use a clear rectification from light and heavy impurities with large reflux numbers and repeated washing at different stages of the emission of isoprene, which complicates the process flow and increases the consumption of the process. In addition, the products of the synthesis of isoprene may be matilal formed in the conditions of synthesis of isoprene from methanol and formaldehyde. Matilal practically not separated from isoprene or a clear rectification (due to the presence of tangential.overlay very energy intensive, obespechenie aqueous solutions of formaldehyde is unstable. All of this adds cost and complexity to the process.

The objective of the invention to reduce the energy intensity of the process and improving the quality of emitted isoprene.

This offers a method of producing isoprene by reacting the isobutene contained in the hydrocarbons of C4with water in the presence of an acid catalyst, followed by separation of the stream containing predominantly formed tert.butanol, interaction obtained tert.butanol with formaldehyde in the presence of an acid catalyst at elevated temperature and pressure with the separation of the reaction mass in water and the oil layer and the release of isoprene from the oil layer by distillation and washing, followed by purification of isoprene from oxygen-containing compounds by extractive distillation using as a selective solvent of the obtained tert. butanol followed by desorption of oxygen-containing compounds from saturated solvent and the flow of desorbed solvent to interact with formaldehyde.

It is preferable to use not a complete desorption of oxygen-containing compounds, and imanol.

In one embodiment, the proposed method obtained tert.butanol containing up to 15 wt. water, is subjected to contact with a liquid stream of isoprene displayed at the top or as a side stream from the top of the extractive distillation column and then separating the formed bottom layer, mainly containing water and an upper layer containing predominantly isoprene and tert.butanol, send in the upper part of the extractive distillation column.

In the present invention, instead of a clear rectification used in the prototype for the purification of isoprene, it is proposed to use extractive rectification. Used as a selective solvent in extractive distillation tert.butanol produced by the interaction of isobutene with water and discharged from the reaction mixture, greatly simplifies and cheapens the process of purification of isoprene. Typically, in systems of extractive distillation solvent circulates through the loop: column extractive distillation of desorber, which inevitably leads to the accumulation in it of impurities and the need for regeneration of the solvent. In the proposed method, all solvent after desorption output of the system is its structure, that significantly reduces the risk of zabivac hardware node extractive distillation salts, resins, polymer and eliminates the need for regeneration of the solvent.

Not a complete desorption of oxygen-containing compounds from the solvent significantly reduces the consumption of power at the stage of desorption. Such an opportunity due to the fact that it is established that the most difficult desorbers from solvent impurities that when you recycle them with the desorbed solvent or decay into lighter components, or, conversely, are repeated reactions with the formation of more taglocity compounds that do not fit into isoprene.

When cleaning isoprene extractive rectification facilitates the selection of isoprene raw preceding rectification, as key taglocity component in the previous allocation of isoprene raw becomes tert. butanol contained in the oil layer. Other undesirable components, even more easily boiling than tert.butanol, separated from isoprene in the conditions of the extractive distillation and therefore, hitting them in the isoprene-raw can be neglected, which can significantly whee it from the oil layer and, accordingly, to reduce the energy consumption of the process. Furthermore, the presence of tert.butanol in the feed to the purification of the isoprene increases the concentration of the selective solvent on the plates of the column extractive distillation and increases the efficiency of the purification of isoprene.

Tert.butanol used in the process, obtained by hydration of isobutylene contained in the hydrocarbon fractions of water in the presence of an acid catalyst, followed by separation of the resulting alcohol from the reaction products. Hydration is usually carried out at 60 130oC and the pressure to ensure the implementation of the process in the liquid phase. As a catalyst can be used in a variety of acid catalysts type: inorganic acids (sulfuric, phosphoric), ion-exchange resins and other Selection rubs.butanol from the reaction products of hydration is carried out by conventional methods (distillation, extraction). When selected tert.butanol can contain up to 15 wt. water. The use of such tert.butanol as a selective solvent can lead to adverse events related to the limited solubility of water in the isoprene-tert.butanolic mixtures. Special dehydration of tert. butanol very energopolevom tert.butanol, containing up to 15 wt. water, liquid flow isoprene displayed at the top or as a side stream from the top of the extractive distillation column, and then separating the formed bottom layer, mainly containing water and an upper layer containing predominantly isoprene and tert. butanol, send in the upper part of the extractive distillation column. The bottom layer, mainly containing water, can be processed either by recycling it to the reactor interaction tert.butanol with formaldehyde, or by his direction in the reaction mixture before separation of the water and the oil layer, or processing it in conjunction with water or oil layers. The upper layer containing predominantly isoprene and tert.butanol has a minimum concentration of tert.butanol at a maximum ratio of isoprene and water compared to all other compounds on the plates in the area of extractive distillation, which excludes the possibility of delamination liquid flows on the plates and associated adverse effects (reducing the efficiency of the plates, the redistribution of inhibitors between the layers and so on).

The interaction of tert.butanol with formaldehyde used in Vistalizator, in which the most frequently used sulfuric or phosphoric acid. Isoprene from the reaction products is highlighted by distillation and washing. When used for purification of isoprene on the proposed method of extractive distillation, from the technological scheme of the emission of isoprene can be excluded washing or washing may be carried forward to the end of the scheme after extractive distillation. The task of cleaning is the cleaning of isoprene from impurities tert.butanol, which will reduce the cost of the separation of isoprene from tert.butanol in the extractive distillation column.

The method is illustrated by the following examples.

Example 1. The reactor, which is a column made of steel 18CR10NITI, an inner diameter of 32 mm, equipped with a "face", which serves for cooling water to remove heat of reaction, filled with a catalyst KU-FPP in the amount of 4.0 l and an aqueous solution containing 12% tertiary butanol. In the bottom of the reactor serves pyrolysis fraction in the amount of 2400 g/h, containing 55% of isobutylene and water in the amount of 415 g/h Molar ratio water:isobutylene

0,98:1,0. The process is conducted at a temperature of 85-90oC and the pressure 18-19 ATI.

From the top of the reactor taken in to the>Water 4,0

Tert-butanol is separated from the hydrocarbon fraction by distillation in the number 1338 g/h, contained as impurities 0.01% hydrocarbon, C4and 7.5% water.

Part of tert-butanol in an amount of 200 g/h were sent to the synthesis of isoprene, part number 1138 g/h was sent as a selective solvent for cleaning selected from reaction products of isoprene from impurities of oxygen-containing compounds.

Synthesis of isoprene lead by the interaction of formaldehyde with tert-butanol in the presence of a catalyst in a pilot unit comprising two successive reaction zones, each containing a reactor made of titanium.

As the catalyst used sulphuric acid.

The reactor of the 1st reaction zone of the hollow volume of the reaction zone 6 liter Reactor 2nd reaction zone has a similar design, the volume of the reaction zone 6 l

Source and recycle the products served in the lower part of the reactor 1 zone. From the upper part of the reactor 1 zone reaction mass is shown in the lower part of the reactor the 2nd zone. From the top of reactor 2-nd zone are reaction products in the vapor phase, which is then condensed and splits into oil is the second thread, containing an aqueous solution of the catalyst after contact with the oil layer for extraction of the aqueous solution of catalyst high-boiling organic products, reciclat in the lower part of the 1st reaction zone. The temperature in the first reactor 130oC, the second 180oC. the contact Time of 22 minutes in each reactor. The pressure in the reactor 21-22 ATI.

As the source and recycle products in the 1st reaction zone serves:

formaldehyde in aqueous solution (formalin) in the amount of 1270 g/h having the following composition, wt.

Formaldehyde 39,5

Methanol 0,5

Water 60,0;

tert-butanol in an amount of 200 g/h obtained at the stage of hydration of isobutylene having the composition specified above;

tert-butanol in the number 1133 g/h of the cube column desorption of oxygen-containing compounds of the purification unit of isoprene from oxygen-containing compounds by extractive rectification with tert-butanol;

recycle isobutylene separated from the oil layer, the number 4450 g/h with after extraction they organic compounds from the aqueous layer as impurities 2 wt. tert-butanol, and a total of 1 wt. dimethyldioxanes, methyldihydromorphine and other organic products;

the impurities total of 3.6 wt. dimethyldioxanes, methyldihydromorphine, unsaturated alcohols C5and other organic products, and 4.4 wt. water;

recycle aqueous solution of the catalyst in the number 2430 g/h with the composition, wt.

Tert-butanol 6,0

Water 92,7

Sulfuric acid 0,5

Dimethyldioxanes, methyldihydromorphine, unsaturated alcohols C5and other organic products 0,8

After condensation and separation of a gas stream selected from the 2nd reaction zone, obtained 6230 g/h oil layer and 1548/h water layer.

The composition of the water and oil layers are given in table. 1.

From the oil layer by using rectification and water washing dedicated isoprene raw number of 880 g/h, containing the following impurities, wt.

Isobutylene 0,27

Hydrocarbons, C50,17

Matilal 0,004

MTBE 0,07

Methanol 0.02

Tert-butanol 0,50

Other admixtures (alcohols, ketones and others) 0,20

Isoprene raw fed to the extractive distillation column having an inner section 12.5 cm2and efficiency to 80 theoretical plates in the point corresponding to the 20th of theoretical plate of a cube column. Column operates under atmospheric pressure at temperate 1138 g/h of tert-butanol, obtained at the stage of hydration of isobutylene, to the point corresponding to the 40th theoretical plate.

As the top product of the column selected after settling gone water isoprene-rectified in the amount of 865 g/h having the following composition, wt.

Isoprene 99,52

Isobutylene 0,27

Hydrocarbons, C50,15

Matilal 0,0001

Methanol is 0.0002

MTBE 0,0001

Water 0.02

Tert-butanol 0,0003

CBM product guide to food in the desorption column section 8.0 cm2and efficiency 40 theoretical plates to extract oxygen-containing organic compounds from saturated tert-butanol in the point corresponding to the 30th theoretical plate from Cuba columns.

Desorption carried out under atmospheric pressure at a temperature of top 50-54oC cube 86-88oC with a reflux ratio equal to 250.

From the top of the columns to display in the amount of 15 g/h fraction of oxygen-containing compounds containing 35 wt. isoprene.

From the cube column purified tert-butanol containing 6,6% water, and 0.2% of other impurities in the number 1133 g/h to send as raw material in the reaction site of synthesis of isoprene.

Example 2. As Eeyore.

Hydration of isobutylene is carried out at 82-87oC and the pressure 18-19 ATI in the reaction apparatus similar to that described in example 1.

For effective heat removal from the upper part of the reaction apparatus deduce aqueous layer is cooled and recycled to the inlet in the lower part of the reaction apparatus.

In the lower part of the reactor serves 3,000 g/h source isobutylester C4-faction, as well as fresh water in the amount of 410 g/h and recycle the water layer in the amount of 3300 g/h

From the top of the reaction device is selected in the number 3440 g/h stream containing 58.6% of hydrocarbon, C4(including 12.1% of the isobutylene), and 37,2% tert-butanol and 3.75% of water.

From the specified stream using distillation separates in the number 1380 g/h of tert-butanol containing 7,0% water, and 0.1% hydrocarbon, C4which is divided into two streams: the first stream in the amount of 280 g/h to send as raw material in the reaction site of synthesis of isoprene, and the second thread in the amount of 1100 g/h serves as a selective solvent in the purification unit of isoprene from oxygen-containing compounds by extractive rectification.

Synthesis of isoprene carry on the PI which are phosphoric acid.

The temperature in the first reaction zone 110oC; in the second reaction zone 165oC. the Pressure in the reaction zones 17-18 ATI. The contact time in each reaction zone 18 minutes

In the lower part of the reaction zone as the source and recycle products serving:

formaldehyde in aqueous solution (formalin) in the amount of 1270 g/h (composition, example 1);

tert-butanol in the amount of 280 g/h obtained at the stage of hydration of isobutylene having the composition specified above;

tert-butanol in the number 1121 g/h of the cube column desorption of oxygen-containing compounds of the purification unit of isoprene from oxygen-containing compounds by extractive rectification with tert-butanol containing 5.8 wt. water;

recycle isobutylene separated from the oil layer, the number 4426 g/h with after extraction they organic compounds from the aqueous layer as impurities 1.7 wt. tert-butanol, and a total of 0.7 wt. dimethyldioxanes, methyldihydromorphine and other organic products;

recycle tert-butanol separated from the heavy part of the oil layer in the amount of 624 g/h containing as impurities total of 5.5 wt. dimethyldioxanes, methyldihydromorphine, unsaturated alcohols C5and the other is g/h, with composition, wt.

Tert-butanol 5,9

Water 88,7

Phosphoric acid 4,5

Dimethyldioxanes, methyldihydromorphine,

unsaturated alcohols C5and other

organic products 0,9

After condensation and separation of a gas stream selected from the 2nd reaction zone, obtained 6282 g/h oil layer and 1531/h water layer.

The composition of the water and oil layers are given in table. 2.

From the oil layer by using rectification and water washing dedicated isoprene raw number of 870 g/h, containing the following impurities, wt.

Isobutylene 0,15

Hydrocarbons, C50,11

Matilal 0,006

MTBE 0,20

Methanol 0,03

Tert-butanol 2,0

Other admixtures (alcohols, ketones and others) 0,20

Isoprene raw, as well as in the amount of 1100 g/h of tert-butanol obtained at the stage of hydration of isobutylene, is fed into the extractive distillation column.

Characteristics of the extractive distillation column, the process parameters of its work and the point of feed flow similar to that shown in example 1.

As the top product of the column selected after settling gone water isoprene-rectified with a concentration 99,6 m

MTBE 0,0003

Methanol 0,0003

Water 0.02

Other impurities 0,0003

CBM product guide to food in the desorption column to extract oxygen-containing organic compounds from saturated tert-butanol. In this case, use the column section 3.2 cm2and efficiency 20 theoretical plates. The saturated flow of extractant served at the point corresponding to the 10th theoretical plate from Cuba columns.

Desorption lead to atmospheric pressure at the top 48-50oC Cuba - 83-85oC with a reflux ratio equal to 50.

From the top of the columns to display in the amount of 8.0 g/h fraction of oxygen-containing compounds containing 40 wt. isoprene.

The degree of desorption of MTBE is 30-35% matilla 50-55% methanol - 40-45%

From the cube column purified tert-butanol in the number 1121 g/h to send as raw material in the reaction site of synthesis of isoprene. Tert-butanol in this case contains the following impurities, wt.

Hydrocarbons, C4-C50,01

Matilal 0,01

MTBE 0,12

Methanol 0.04

Water 5,8

Other impurities 0,1

Example 3. Work site hydration of isobutylene not differ from the one described in example 2. Obtained at the stage of hydrate is 80 g/h serves as a selective solvent in the purification unit of isoprene from oxygen-containing compounds by extractive rectification.

Synthesis of isoprene is carried out on pilot plant described in example 1.

As a catalyst for the process using phosphoric acid.

The temperature in the first reaction zone 100oC; in the second reaction zone 135oC. the Pressure in the reaction zones 14-15 ATI. The contact time in each reaction zone 20 minutes

In the lower part of the first reaction zone as the source and recycle products serving:

formaldehyde in aqueous solution (formalin) in the number 1312 g/h (composition, example 1);

tert-butanol in the number 1610 g/h of the cube column desorption of oxygen-containing compounds of the purification unit of isoprene from oxygen-containing compounds by extractive rectification with tert-butanol, containing 5.0 wt. water.

recycle isobutylene separated from the oil layer, the number 4430 g/h with after extraction they organic compounds from the aqueous layer as impurities 2.0 wt. tert-butanol, and a total of 0.5. dimethyldioxanes, methyldihydromorphine and other organic products.

recycle tert-butanol separated from the heavy part of the oil layer, in the amount of 405 g/h, containing as impurities summary, is also of 5.4 wt. water;

recycle aqueous solution of the catalyst in the amount of 2650 g/h with the composition, wt.

Tert-butanol 6,2

Water 82,8

Phosphoric acid 10,3

Dimethyldioxanes, methyldihydromorphine,

unsaturated alcohols C5and other organic products 0,7

After condensation and separation of a gas stream selected from the 2nd reaction zone, obtained 6321 g/h oil layer and 1529/h water layer.

The composition of the water and oil layers are given in table. 3.

From the oil layer by using rectification and water washing dedicated isoprene raw number 1062 g/h, containing the following impurities, wt.

Isobutylene 0,15

Hydrocarbons, C50,11

Matilal 0,005

MTBE 0,29

Methanol 0,03

Tert-butanol 19,8

Other admixtures (alcohols, ketones and others) 0,25

Isoprene raw, and the number of 1380 g/h of tert-butanol obtained at the stage of hydration of isobutylene, is fed into the extractive distillation column.

Characteristics of the extractive distillation column, the process parameters of its work and the point of feed flow similar to that shown in example 1.

As the top product of the column from which ASI impurities, wt.

Hydrocarbons, C4-C50,27

Matilal 0,0001

MTBE IS 0.0002

Methanol is 0.0002

Water 0.8

Tert-butanol is 0.0002

CBM product guide to food in the desorption column described in example 2, the point corresponding to the 10th theoretical plate from the cube column. Technological parameters desorption columns is similar to that described in example 2.

From the top of the columns to display in the amount of 8.5 g/h fraction of oxygen-containing compounds containing 34 wt. isoprene. The degree of desorption of MTBE 35-40% of matilla 50-55% methanol 45-50%

From the cube column purified tert-butanol in the number 1610 g/h to send as raw material in the reaction site of synthesis of isoprene. Tert-butanol in this case contains the following impurities, wt.

Hydrocarbons, C4-C50,01

Matilal 0,01

MTBE 0,14

Methanol 0,03

Water 5,0

Tert-butanol 0,1

Example 4

As isobutylester raw materials use C4-faction with 42.6% of isobutylene.

The hydration is carried out in a reaction-extraction apparatus column type inner diameter of 60 mm, loaded 10,0 l sulfonate catalyst KU-FP.

St. the share.

The process is carried out at a temperature of 80 85oC and a pressure of 19 20 ATA. The molar ratio of water isobutylene 18,7 1,0.

From the top of the apparatus taken in the amount of 1437,8 g/h, C4the fraction containing 2.5% isobutylene, and 1.6% of tert-butanol and 0.1% of water, from which further separated by distillation in an amount of 23 g/h of tert-butanol, containing 0.2% of a hydrocarbon, C4directed at the reaction site of synthesis of isoprene.

From the cube display apparatus in the amount of 15462,2 g/h water flow containing 8.3% of tert-butanol, which is directed to the power in a distillation column to retrieve tert-butanol.

From the rectifying column bottom water containing 0.2% tert-butanol in the number 13955,5 g/h return in the reaction-extraction apparatus for the hydration, and the top product of the distillation column tert-butanol containing 15,0% water, in the amount of 1506,8 g/h is directed to the production of isoprene in the purification unit of isoprene from oxygen-containing compounds by extractive rectification as selective solvent.

Synthesis of isoprene is carried out on pilot plant described in example 1.

As a catalyst for the process uses sulfuric acid.

In the lower part of the first reaction zone as the source and recycle products serving:

formaldehyde in aqueous solution (formalin) 1326 g/h (composition, example 1);

tert-butanol in the amount of 1560 g/h of the cube column desorption of oxygen-containing compounds of the purification unit of isoprene from oxygen-containing compounds by extractive rectification with tert-butanol, containing 5.3 wt. water;

recycle isobutylene separated from the oil layer, the number 5035 g/h with after extraction they organic compounds from the aqueous layer as impurities 1.6 wt. tert-butanol, and a total of 0.6. dimethyldioxanes, methyldihydromorphine and other organic products;

recycle tert-butanol separated from the heavy part of the oil layer, in the amount of 550 g/h containing as impurities total of 5.4 wt. dimethyldioxanes, methyldihydromorphine, unsaturated alcohols C5and other organic products, but also of 6.7 wt. water;

recycle water stream from the container in which the mixture of the source of tert-butanol with a part of the reflux stream of the column extractive distillation, in the amount of 165 g/h;


Water 93,4

Sulfuric acid 0.4

Dimethyldioxanes, methyldihydromorphine, unsaturated alcohols C5and other organic products 1,0

After condensation and separation of a gas stream selected from the 2nd reaction zone, obtained 7107 g/h oil layer and 2540 g/h of the water layer.

The composition of the water and oil layers are given in table. 4.

From the oil layer by using rectification and water washing dedicated isoprene raw number 1062 g/h containing 19,9% tert-butanol, and the following impurities, wt.

Isobutylene 0,16

Hydrocarbons, C50,17

Matilal 0,0015

MTBE 0,12

Methanol 0.04

Other admixtures (alcohols, ketones and others) 0,32,

which serves to remove oxygen and heavy impurities in the extractive distillation column, having a cross-section 12.5 cm2and efficiency 60 theoretical plates, to the point corresponding to 50 theoretical plate from Cuba columns.

Column operates under atmospheric pressure at a temperature of top 35 - 36oC cube 85 87oC with a reflux ratio equal to 2 2,1 (ratio of flow returned to the column to select distillate is 4 to 1, but part of the flow is directed to mix with the source is t and is directed into the container, equipped with a settling zone for mixing with a part of the flow phlegmy column extractive distillation in the number 1685/h

Delamination is carried out at a temperature of 40 45oC. breaking Time 16 20 min.

From the specified capacity after separation of the mixture deduce the number 3027 g/h of hydrocarbon layer composition, wt.

Isoprene 55,3

Tert-butanol 41,6

Water 3.1,

served in the extractive distillation column as a selective solvent, as well as in the amount of 165 g/h water layer containing 86,1 wt. water and 13.9 wt. tert-butanol which is sent together with a recycle stream of tert-butanol in the reaction site of synthesis of isoprene.

As the top product of the column extractive distillation selected after settling gone water isoprene-rectified with a concentration of 99.4 wt. the number 837 g/h containing impurities, wt.

Hydrocarbons, C4-C50,33

MTBE IS 0.0002

Methanol 0,0001

Matilal 0,0001

Water 0,09

Tert-butanol 0,12

Next isoprene-rectified can be directed into a column of water washing to remove impurities tert-butanol to achieve curing of purity.

Cube is eroticheskoe plate from Cuba columns.

The column in this case operates under atmospheric pressure at a temperature of top 50 53oC cube 83 85oC with reflux ratio of 200.

The degree of desorption of oxygen-containing impurities (MTBE, matilla, methanol) is from 90 to 96%

From the top of the columns to display in the number of 16.3 g/h fraction of oxygen-containing compounds containing 37 wt. isoprene.

From the cube column purified tert-butanol in the amount of 1560 g/h containing 5.3 wt. water, and 0.2 wt. other impurities are sent as raw material in the reaction site of synthesis of isoprene.

Example 5. Work site hydration of isobutylene not differ from the one described in example 4. Synthesis of isoprene is carried out on pilot plant described in example 1. As the catalyst used sulphuric acid.

Conditions for the synthesis of isoprene is similar to that described in example 4.

In the lower part of the first reaction zone as the source and recycle products serving:

formaldehyde in aqueous solution (formalin) in the number 1336/h (composition, example 1);

tert-butanol in the number 1572 g/h of the cube column desorption of oxygen-containing compounds of the purification unit of the isoprene from the oxygen-containing soedinenii from the oil layer, the number 5025 g/h with after extraction they organic compounds from the aqueous layer as impurities 1.8 wt. tert-butanol, and a total of 0.55 wt. dimethyldioxanes, methyldihydromorphine and other organic products;

recycle tert-butanol separated from the heavy part of the oil layer, in the amount of 632 g/h containing as impurities total of 4.9 wt. dimethyldioxanes, methyldihydromorphine, uncertain alcohols C5and other organic products, as well as to 6.4 wt. water;

recycle water flow from the tank, which was carried out by mixing the source of tert-butanol with the flow, derived from extractive distillation column at a point on 5 plates above the point of feed of the selective solvent, in the amount of 156 g/h;

recycle aqueous solution of the catalyst in the amount of 1838/h with the composition, wt.

Tert-butanol 6,2

Water 93,35

Sulfuric acid 0,45

Dimethyldioxanes, metalhydrogen, uncertain alcohols C5and other organic products 1,0

After condensation and separation of a gas stream selected from the 2nd reaction zone, obtained 7095 g/h oil layer and 2522 g/h of the water layer.

The composition of the water and oil layers, primaires in the number 1081 g/h, containing 19,9% tert-butanol, and the following impurities, wt.

Isobutylene 0,15

Hydrocarbons, C50,17

Matilal 0,0011

MTBE 0,10

Methanol 0.04

Other admixtures (alcohols, ketones and others) 0,30,

served in the extractive distillation column for purification from oxygen and heavy impurities.

The column has a cross section 12.5 cm2the efficiency 80 theoretical plates and operates under atmospheric pressure at a temperature of top 35 - 36oC cube 85 88oC with a reflux ratio equal to 4.

The flow of tert-butanol node hydration of isobutylene in the number 1506,8 g/h is cooled and sent to storage capacity, equipped with a settling zone for mixing with the stream output from the extractive distillation column at a point corresponding to the 50th theoretical plate from Cuba columns, the number 4160 g/h

Delamination is carried out at 40 45oC. breaking Time of 10 to 12 minutes

From the specified capacity after separation of the mixture deduce the number 5511 g/h of hydrocarbon layer composition, wt.

Isoprene 71,5

Tert-butanol 26,7

Water 1,8,

served in the extractive distillation column as a selective solvent in point of obstructive sleep apnea. tert-butanol which is sent together with a recycle stream of tert-butanol in the reaction site of synthesis of isoprene.

As the top product of the column extractive distillation selected after settling gone water isoprene-rectified with a concentration of a 99.6 wt. the number of 855 g/h containing impurities, wt.

Hydrocarbons, C4-C50,32

MTBE 0,0001

Methanol 0,0001

Water 0,08

Tert-butanol is 0.0002

CBM product guide to food in the desorption column described in example 1 in the point corresponding to the 30th theoretical plate from Cuba columns.

Desorption carried out under atmospheric pressure at a temperature of top 50 53oC cube 84 87oC with reflux ratio of 200.

The degree of desorption of oxygen-containing impurities (MTBE, matilla, methanol) is from 90 to 98%

From the top of the columns to display in the amount of 14.3 g/h fraction of oxygen-containing compounds containing 40 wt. isoprene.

From the cube column purified tert-butanol in the number 1572/h, containing 4.5 wt. water, and 0.2 wt. other impurities are sent as raw material in the reaction site of synthesis of isoprene.

Literature

1. Paaske and products of its oxidation". M. Chemistry, 1973, S. 182 186.

2. The oil and Gas Journal. June 26, 1972, p. 66 67.

1. A method of producing isoprene by reacting the isobutene contained in the hydrocarbons of C4with water in the presence of an acid catalyst, followed by separation of the stream containing predominantly formed tert.butanol, interaction obtained tert.butanol with formaldehyde in the presence of an acid catalyst at elevated temperature and pressure with the separation of the reaction mass in water and the oil layer and the release of isoprene from the oil layer by using rectification and, possibly, water washing, characterized in that the isoprene purified from oxygen-containing compounds by extractive distillation using as a selective solvent of the obtained tert.butanol followed by desorption of oxygen-containing compounds from saturated solvent and the flow of desorbed solvent to interact with formaldehyde.

2. The method according to p. 1, characterized in that from the saturated solvent is desorbed 30 95% oxygen-containing compounds.

3. The method according to PP. 1 and 2, characterized in that applied to the purification of isoprene contains a 2.0 is about 15 wt. water, is subjected to contact with a liquid stream of isoprene displayed at the top or as a side stream from the top of the extractive distillation column, and then separating the formed bottom layer, mainly containing water and an upper layer containing predominantly isoprene and tert.butanol, send in the upper part of the extractive distillation column.

 

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The invention relates to an improved method for producing a joint production of isoprene and 3-methylbutan-1, which are used in the IC industry and petrochemistry

The invention relates to petrochemistry, namely the one-step method for the production of isoprene from formaldehyde and isobutylene and/or trimethylamine in the presence of acid catalysts

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The invention relates to a method for dehydrogenation of hydrocarbons

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

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