Method of production of isoprene

FIELD: one-stage production of isoprene.

SUBSTANCE: proposed one-stage production method includes continuous or cyclic delivery of isobutylene and/or tert-butanol, formaldehyde and water to aqueous acid solution and interaction of reaction mixture at distillation of mixture containing isoprene to be produced, water, unreacted starting materials and other low-boiling components from reaction mixture beyond reaction system where said reaction is conducted at regulation of concentration of high-boiling byproducts which are accumulated in said reaction mixture at interval of from 0.5 to 40 mass-%.

EFFECT: enhanced efficiency.

10 cl, 2 dwg, 1 tbl, 13 ex

 

The technical field to which the invention relates

The present invention relates to a method of producing isoprene, which is effectively used as a basic chemical raw material for various chemicals and polymeric materials.

Background of invention

As a method of producing isoprene known is a method that contains a continuous or periodic supply of isobutylene and/or tert-butanol (hereinafter "the isobutene and/or tert-butanol is sometimes commonly referred to as "C4"), formaldehyde and water in a reactor containing acidic aqueous solution, and carrying out the reaction with distillation of the resulting isoprene together with water and other low-boiling components from the reaction system (for example, JP-A-59-70623).

In addition, a method of obtaining described in JP-A-59-70623, part of a mixture With4, formaldehyde, water and acid aqueous solution (hereinafter abbreviated referred to as the "reaction mixture") is withdrawn from the reactor, is heated together with at least part of the4and then inject the mixture again into the reactor (for example, JP-A-59-190930). It should be understood that the term "water" includes water solution, such as acid aqueous solution and the like, and the reaction mixture can contain the reaction product and by-products.

In addition, the known method is perceived by the Oia, isoprene, which differs in that in the production method, described in JP-A-59-70623, the amount of heat from the water is removed partially or mainly of water in the resulting isoprene, water, unreacted raw materials and other low-boiling components, which distills from the reaction system in the form of a gas (hereinafter "the resulting isoprene, water, unreacted starting materials and other low-boiling components are indicated in abbreviated form as "reaction distillation gas"), the amount of heat unfused gas is used as a heat source for evaporation of isobutylene, a heat source to extract unreacted isobutylene distillation of the organic layer received by the concentration and phase separation of the reaction distillation gas and the like (for example, JP-A-60-4138).

In addition, the known method of producing isoprene, which differs in that for the separation of high-boiling by-products accumulated in the reaction mixture, the residue or part thereof, which is obtained upon evaporation of the unreacted starting materials and isoprene from the organic layer of the distillate in the reaction, is added to the reaction mixture, or part thereof, and the organic layer containing the high-boiling by-products, is separated from the acidic aqueous solution (for example, JP-A-59-116236).

Specifically, when a simple implementation of the methods of preparation, are described in JP-A-59-70623, JP-A-59-190930 and JP-A-59-116236, the concentration of high boiling point byproducts in the reaction mixture has fluctuations that, in turn, makes unstable the concentration of acid in the reaction mixture, causes corrosion of equipment and degrades the performance of the reaction production of isoprene.

In particular, it was found that when a portion of the reaction mixture withdrawn from the reactor and is heated with at least a part of the4, not enough heat is transferred to the reaction mixture at too high or too low concentration of high-boiling by-products in the reaction mixture. When not enough heat is transferred, the reaction mixture in the reactor is rapidly cooled, and the amount of water warded off in the reaction, tends to decrease. Therefore, for a continuous reaction, it is necessary that the quantity of an aqueous solution of formaldehyde was reduced with the constant maintenance of the surface of the reaction mixture at a certain level, which in turn often reduces the amount of isoprene per unit time.

On the other hand, when the temperature of the reaction mixture in re store is constantly maintained at a certain level, in this case, when excessive heating of the reaction mixture withdrawn from the reactor, and at least part C4there are some disadvantages, such as lower efficiency of the amount of heat required for the production of isoprene, easy blockage of pipes accumulated them in high-boiling by-products, etc.

In the method described in JP-A-60-4138, the amount of heat possessed by the reaction distillation gas, can be effectively recovered. However, it is not enough as replenishment of heat necessary for its production of isoprene, and a camera for its improvement before industrial application.

Therefore, the aim of the present invention is to overcome the above problems and to provide a method that allows to obtain isoprene is more effective than traditional methods.

Description of the invention

The present invention achieves the above objectives the following characteristics :

(1) a Method of producing isoprene, which contains continuous or periodic supply of isobutylene and/or tert-butanol, formaldehyde and water in the acid aqueous solution and the interaction of the reaction mixture during the distillation of a mixture containing the resulting isoprene, water, unreacted starting materials and other low-boiling components, indicated the reaction mixture outside the reaction system, in which the above reaction is carried out under the regulation of the concentration of high-boiling by-products, which are produced and accumulated in the above reaction mixture, with a hit in the interval of 0.5-40 wt.%.

(2) a Method of producing isoprene under item(1), in which the concentration of high boiling point byproducts in the reaction mixture govern hit in the above interval, providing a release for the selection of the reaction mixture from the reactor containing the reaction mixture, the selection of the reaction mixture from the release and separation and removal of at least part of the high-boiling by-products from the reaction mixture, followed by introduction of the remaining reaction mixture again into the reactor.

(3) a Method of producing isoprene by p.(2), in which the release for the selection of the reaction mixture is located, at least in the bottom of the reactor.

(4) a Method of producing isoprene by p.(2) or (3)in which the release for the selection of the reaction mixture is placed in the side wall of the reactor, and the release level set so that the volume of the reaction mixture is filled up to a level that is not less than 1/2 of the total volume of the reaction mixture in the process of producing isoprene.

(5) a Method of producing isoprene in percentage points (1)to(4), in which the mixture containing the resulting isoprene, water, unreacted starting materials and other low-boiling components, Otho Aut from the reaction system as the reaction distillation gas, water fractional condensation of the reaction distillation gas and the resulting water is injected back into the reactor to control the concentration of high-boiling by-products in the reaction mixture to contact the above interval.

(6) a Method of producing isoprene in percentage points (1)to(5), in which the concentration of high boiling point byproducts in the reaction mixture regulate to hit the above interval by setting the reactor mixing device having a mixing blade that is designed for horizontal rotation in the reaction mixture, and the filing of isobutylene and/or tert-butanol are added to the mixing blades of the inlet formed facing the pipe directly below the mixing blades in the reactor.

(7) a Method of producing isoprene in percentage points (1)to(6), in which the concentration of high boiling point byproducts in the reaction mixture regulate to hit the above interval by setting the reactor mixing device having a mixing blade that is designed for horizontal rotation in the reaction mixture in which part of the reaction mixture withdrawn from the reactor, is heated at least part of the isobutene and/or tert-butanol in the heat exchanger and is introduced again into the reactor, and feeding the heated reaction mixture to a mixing lop the STI from the inlet, formed in the reactor.

Brief description of drawings

Figure 1 presents a diagram of the device for explanation of the method of obtaining of the present invention.

Figure 2 is a flow diagram showing the structure of the equipment, designed for the method of obtaining of the present invention in examples of the present invention. In heat exchangers 2, 3, 5, 6, 7, and 11, shown here, the connection of the heat exchanger is shown schematically by solid lines and broken lines to illustrate the ratio of the intake/release pipeline, but they do not show the shape of the inside of the pipeline.

The symbols shown in figures 1 and 2, are described as follows: A - the reaction mixture, P1-P10 - pipes, 1 - reactor, 2, 3, 5, 6, 7, 11 and 12 - exchangers, 4 - capacity separation of high-boiling by-products, 8, 9 and 13 - a collection of distillate, 10, 14 - distillation column.

The best option of carrying out the invention

In the method of producing isoprene present invention, as shown schematically in the diagram of the device in figure 1, With4continuously or periodically served by pipeline P6, and formaldehyde and water - pipe P1 in acidic aqueous solution in the reactor 1, and the reaction mixture And interacts with the distillation of this reaction mixture And the mixture containing isoprene water, unreacted starting materials and other low-boiling components, is outside the reaction system by distillation pipeline P2 as the reaction distillation gas. The main technology of this method of production is the same as the technology known method of producing isoprene, and reference may be made to the above-mentioned JP-A-59-70623, JP-A-59-190930, JP-60-4138 and JP-A-59-116236.

Here is unusual important characteristics of the present invention is that the above receipt of isoprene is carried out while regulating the concentration of high-boiling by-products in the above reaction mixture (not shown)that is received and accumulated in the specified reaction mixture, in the range from 0.5 to 40 wt.%.

For example, JP-A-59-70623 describes the removal of high-boiling by-products that accumulate in the reaction, and their processing, but not described the effect of the concentration of high-boiling by-products on the results of the reaction. On the contrary, in the present invention has a new effect and the effect that can occur in the presence of a specified number of high-boiling by-products in the reaction mixture, and the invention is characterized by the phase adjustment removal of high-boiling by-products, so that its concentration falls in the range of 0.5-40 m is S.%.

High-boiling by-products, the concentration of which should be regulated, usually uniformly dispersed in the liquid in the reactor. Depending on the efficiency of mixing, however, they may be distributed unevenly in the upper or lower part of the reaction mixture. Although the components of the high-boiling by-products cannot be precisely defined, can be specified organic compounds having a high boiling point (for example, polymers of product and by-products in the method of producing isoprene present invention and the like), raw materials, impurities, such as inorganic substances, obtained from the reactor, etc.

When regulating the concentration of high boiling point byproducts in the reaction mixture in the range of 0.5-40 wt.% they preferably act as carriers. Thus, the efficiency of heating of the reaction mixture using a heat exchanger, etc. can be maintained at a preferable level, and, in addition, have no place violations such as a blockage of the pipeline due to the high-boiling by-products, etc. In the isoprene can be obtained more efficiently than before.

The concentration of high boiling point byproducts in the reaction mixture, more preferably, is in the range of 1-30 wt.%, and, particularly preferably, online is rule 2-20 wt.% to simultaneously achieve improved heat transfer and to prevent violations, such as plugging, pipeline, etc.

When the concentration of high-boiling by-products is less than 0.5 wt.%, the efficiency of heating of the reaction mixture decreases, which, in turn, reduces the temperature of the reaction mixture in the reactor, reduces warded off the water and reduces the amount of aqueous solution of formaldehyde fed to the reactor to maintain the reaction mixture in the reactor at a certain level, thereby reducing the amount of isoprene per unit of time. To prevent decrease of the above-mentioned temperature of the reaction mixture in the reactor, the reaction mixture may be excessively heated in the heat exchanger. However, this method causes problems, including reduced efficiency of the heat quantity required for production of isoprene, clogging of pipelines high-boiling by-products result from the accumulation of high-boiling by-products in the pipeline and the susceptibility to corrosion of acid, due to the temperature near the surface of the heat exchanger, which is too high.

On the other hand, the concentration of high-boiling by-products, which is more than 40 wt.%, causes problems, including rapid clogging of the piping between the heat exchanger and the reactor, the internal piping of the heat the exchanger, etc., thus, causing disruption, low efficiency of heat (efficiency of supplied heat) of the reaction mixture in the heat exchanger and a light concentration of circulating the reaction mixture with korrodirovaniju equipment highly concentrated acid, etc.

Although the method of regulating the concentration of high boiling point byproducts in the reaction mixture with a hit in the above interval is not specifically limited, for example, the type of regulation with feedback, containing a selection of the reaction mixture (hereinafter selected reaction mixture is sometimes referred to as "selected reaction mixture"), removing at least part of the high-boiling by-products selected from the reaction mixture a suitable processing method, shown below, and return the selected reaction mixture after removing processing (hereinafter sometimes referred to as "reaction mixture after removing processing") in the reactor are a suitable method of control. In the example in figure 1, the reaction mixture is withdrawn from the pipeline P3 and/or P4, high-boiling by-products are separated and removed in the vessel branch of the high-boiling by-products 4, and the reaction mixture after removing processing is returned through the pipeline P5 in the reactor.

Although the method of separation and removal Vysockij the side products from the reaction mixture in the vessel branch of the high-boiling by-products 4 is not specifically limited, preferably, can be used, for example, the method of extraction using an organic solvent.

The selection of the reaction mixture in the reactor can be carried out continuously or periodically. In addition, the number of selected reaction mixture can be determined, taking into account the accumulated quantity of high-boiling by-products in the reactor, etc. as a way of sampling the reaction mixture may be specified, for example, the method that contains the regulation of the concentration of high boiling point byproducts in the reaction mixture with a hit in the interval of 0.5-40 wt.% in continuous sampling the reaction mixture at the rate of 2 l/h in a reactor having an internal volume of 120 l, etc.

The method of determining the concentration of high boiling point byproducts in the reaction mixture is not specifically limited. Since the high-boiling by-products harden, when a portion of the reaction mixture is collected and cooled, can be specified, for example, the method containing the separation of solidified high-boiling by-products, measuring their mass and calculating the concentration of high boiling point byproducts in the reaction mixture, etc.

The formaldehyde used in the present invention, serves as an aqueous solution in the reactor. From the viewpoint of reducing the amount of heat transferred to concomitantly the water, or the amount of heat required for the production of isoprene, the optimal concentration of an aqueous solution of formaldehyde is the highest. The concentration of an aqueous solution of formaldehyde is usually preferably in the range of 20-70 wt.%, more preferably, in the range of 25-60 wt.%. When the concentration of an aqueous solution of formaldehyde is too high, there is the problem of deposition of paraformaldehyde.

Used in the present invention With4may include 3-methylbutane-1,3-diol, 3-methyl-2-butene-1-ol, 3-methyl-3-butene-1-ol, 3-methyl-1-butene-3-ol, methylisobutylketone, 2-methylbutanal, methyl-tert-butylphenyl, 4,4-dimethyl-1,3-dioxane, 4-methyl-5,6-dihydro-2H-Piran, etc. in Addition, it may include a simple methyl tert-butyl ether and the like, which decomposes in the reaction conditions on isobutylene and tert-butanol.

The acid aqueous solution used in the present invention, is an aqueous solution of acidic substances, such as inorganic acid, organic acid, salt, etc. as acidic substances are preferred acidic substances, non-volatile or low-volatile under the reaction conditions. Can be specified, for example, inorganic acids (phosphoric acid, sulfuric acid, boric acid, and the like), heteroalicyclic (kremneva.liliya acid, ghostwolf the mill industry acid and the like), organic acids (pair-toluensulfonate, benzosulfimide, triftoratsetata, oxalic acid and the like), acid salts (acidic sodium sulfate and the like), etc.

Although the pH of the acidic aqueous solution may vary depending on the kind of the acidic substance, the reaction temperature, feed rate With4, the speed of feeding of formaldehyde and the like, it is usually preferably in the range of pH 0.5 to 2.5, more preferably in the range of pH 1-2.

In the method of producing isoprene present invention, the reaction can be carried out simultaneously filling, in addition to the reaction mixture, low-boiling compounds and inert in the reaction conditions, or inert gas into the reactor, if necessary. As a low-boiling compounds, preferred are hydrocarbons, particularly hydrocarbons having 1-10 carbon atoms, such as n-propane, n-butane, n-hexane, cyclohexane, etc. as preferred inert gas is nitrogen, etc.

The molar ratio of C4and formaldehyde fed to the reactor (hereinafter referred to as "C4/formaldehyde"), is preferably not less than 3, more preferably not less than 5. Although the molar ratio of no upper limit in the strict sense, excessive molar ratio slightly improves the yield of isoprene. On the contrary, it is I who is economic disadvantage, because it increases the required amount of heat for the production of isoprene. Typically, the value Of4/formaldehyde is preferably not more than 20, more preferably not more than 12. When the value Of4/formaldehyde is less than 3, the output of isoprene has a tendency to decrease.

As is clear from the above molar ratio With4and formaldehyde, in the present invention With4used in excess with respect to formaldehyde. In the production method of the present invention therefore excessive amount of With a4fed to the reactor, Argonauts in unreacted condition of the reaction distillation gas together with the received isoprene, low-boiling components and water outside the reaction system. Unreacted4, distilled from the reaction system can be selected/extracted from other cast components and reused in the production method of the present invention.

Unreacted4, distilled from the reaction system has a composition close to the equilibrium composition of isobutylene and tert-butanol in the reaction conditions. Even when only one of the isobutylene and tert-butanol fed into the reactor as a starting material in the production method of the present invention, if the unreacted source materialists/removed and re-used to reduce the basic amount of the source material, this is comparable to the use of a mixture of isobutylene and tert-butanol as the starting material.

As indicated above, the present invention uses a method of containing continuous or periodic supply With4, formaldehyde and water in acid aqueous solution, and carrying out the reaction in the distillation of a mixture containing the resulting isoprene, water, unreacted starting material and other low-boiling components from the specified reaction mixture as the reaction distillation gas outside the reaction system.

For production of isoprene with high yield, it is preferable that the pressure in the reactor (when low-boiling compounds and inert in the reaction conditions, are served together with the source material, the pressure after subtracting the partial pressure) was in the range of 1.1 to 2.5 times, more preferably 1.1 to 2 times higher than the vapor pressure-water-acid solution at the reaction temperature.

Vapor pressure-water-acid solution at the reaction temperature (hereinafter abbreviated as Pw) is a physical constant that uniquely identified on the basis of the type and concentration of acid substances contained in the reaction mixture. When the pressure in the reactor exceeds Pw 2.5 times the yield of isoprene has a tendency to a significant reduction. On the other hand, when the pressure in the reactor exceed the t Pw less than 1.1 times, the yield of isoprene is not a significant reduction, but the degree of conversion of formaldehyde is reduced, and decreases the ratio of water to isoprene in the reaction distillation gas. This entails an increase in the amount of heat consumed in the reaction, namely the amount of heat required for the production of isoprene, which is economically disadvantageous.

The preferred reaction temperature in the present invention is determined, taking into account the concentration of acid in the reaction mixture, and is usually preferably in the range of 150-220°C. When the reaction temperature is below 150°With the output of isoprene has a tendency to decrease, even when the concentration of the acid aqueous solution is increased to maintain the reaction rate at a constant level. On the other hand, even when the reaction temperature exceeds 220°, isoprene selectivity is not significantly reduced; however, the degree of conversion of formaldehyde under conditions that provide optimum selectivity decreases. On the contrary, when chosen such reaction conditions that can increase the degree of conversion of the formaldehyde, the target reaction from isoprene lead to an increase in by-products that, in turn, adversely reduces the selectivity of the production of isoprene.

The preferred feed rate East is cnica formaldehyde (aqueous solution of formaldehyde) in the reactor is determined, taking into account the concentration of acid in the reaction mixture, the reaction temperature and pressure response.

To increase the feeding speed of the source of the formaldehyde concentration of the acid in the reaction mixture must be increased or the reaction temperature must be increased. In this case there is a problem of corrosion of the reactor. Although the feed speed of the source of formaldehyde has no lower limit, too low feed rate causes a decrease in the volumetric efficiency. Thus, the feed speed of the source of formaldehyde, turned into formaldehyde, is usually preferably in the range of 0.2 to 3 mol/h, more preferably in the range of 0.5 to 2 mol/h per 1 kg of the reaction mixture.

The amount of water fed to the reactor, usually adjusted so that the amount of the reaction mixture in the reactor is maintained at a constant level. Therefore, the specified number is determined by the amount of water removed from the reactor, and the amount of water is increased or reduced by the reaction.

As stated above, because of the components constituting the reaction distillation gas, water has a high boiling point, when the pressure in the reactor is high, the ratio of water to total amount of all components, except water, in the reaction distillation gas is reduced, and when the pressure is low, the ratio of the giving of water increases. Therefore, we can say that the ratio of moles of water removed from the reactor, and moles removed raw materials and products is determined by the pressure in the reactor. In addition, since the moth whisked raw materials and products are almost identical to the moles served With4the ratio of distilled water to the supplied4can also be determined by the pressure in the reactor. Therefore, the amount of water supplied can be determined, taking into account the pressure in the reactor, the quantity supplied4and the increase or reduction of the water due to the reaction.

As indicated above, the high-boiling by-products are formed and accumulated in the reaction mixture when the reaction is carried out in a long time. Such high-boiling by-products show phase separation and dispersed in the reaction mixture, a portion of the reaction mixture in the reactor continuously or periodically withdrawn and sent to the capacity of the Department of high-boiling by-products (for example, the apparatus for decanting, extraction column, and so on) to remove at least part of the high-boiling by-products, so their concentration is regulated.

However, since the relative density of these high-boiling by-products is only slightly different from the relative density d is klonoa mixture, and by-product having a high relative density in comparison with the reaction mixture, and by-product having a low relative density in comparison with the reaction mixture are present in a mixture, the division operation of division, using the relative difference of density, such as decantation, etc. is difficult. Since the high-boiling by-products harden at room temperature, can be used in the method containing the decrease in the temperature of the reaction mixture, providing the solidification of the high-boiling by-products, and then removing by-product separation. In this case, you must re-apply heat to the reaction mixture. From these points of view the destruction of extraction using an extraction solvent is preferred to facilitate the separation of high-boiling by-products from the reaction mixture.

As such extraction solvents is preferred hydrocarbon having a lower boiling point than the boiling point of water, having a lower solubility in water and which is liquid at normal pressure, such as n-hexane, cyclohexane, etc.

As extraction solvents may be used in connection distillation residue after the distillation of unreacted IP is adnych materials and isoprene from organic matter, contained in the reaction distillation gas removed from the reactor outside the reaction system, or a subset of it. As compounds contained in the distillation residue can be specified 4-methyl-5,6-dihydro-2H-Piran, methylisobutylketone, 2-methylbutanal, 2,6-dimethyl-2,5-heptadien, 2,6-dimethyl-1,5-heptadiene, 3-methyl-3-butene-2-ol, etc. in Addition to them, can be specified compound having 4-15 carbon atoms and various functional groups.

When the method of the present invention, the reactor may be installed in the heating device to provide the amount of heat required for the production of isoprene, and the amount of heat required for distillation of isoprene, water, unreacted starting materials and other low-boiling components. Preferred option is to install a suitable auxiliary heating device. As shown in figure 1, can be specified, for example, heating the reaction mixture design, in which the heat exchanger 3 is installed as an auxiliary heating device on the outside of the reactor, and the reaction mixture is circulated between the reactor 1 and the heat exchanger 3 through pipelines P7 and P9, etc.

In this embodiment, when the reaction mixture is heated at its direct circulation in the outer is the heat exchanger, the boiling point of the reaction mixture in the heat exchanger is high compared with the reaction mixture in the reactor, because the amount of isobutylene dissolved in the reaction mixture in the heat exchanger is small, that is, in turn, leads to a surprisingly high temperature of the reaction mixture in the heat exchanger. This increase in the temperature of the reaction mixture increases adverse reactions, which then reduces the yield of isoprene. To prevent this, as shown in figure 1, the preferred option, in which at least part of the4introduced by pipeline R8 in the reaction mixture, selected by pipeline P7 for circulation, they are heated together in the heat exchanger 3 and is introduced into the reactor 1 via line P9.

However, tert-butanol has a markedly small, the effect of preventing the temperature rise of the reaction mixture by heat compared with isobutylene. In addition, the isobutylene is preferred because of tert-butanol is converted to isobutylene in contact with an acid aqueous solution in the heat exchanger and then gives deteriorating effect when4introduced into the reaction mixture, is selected for heat circulation.

In the present invention the amount of heat possessed by the reaction distillation gas can be extracted and efficiency is actively used to produce isoprene.

Alternatively, the extraction amount of heat can be shown, for example, a case where the amount of heat possessed by water, extracted by fractional condensation, mainly water in the reaction distillation gas (for example, in figure 2, the water fraction is condensed in the heat exchanger 5).

As the use of the extracted amount of heat can be specified using the amount of heat unfused reaction distillation gas as a heat source for evaporation of isobutylene (e.g., the source of heat in the heat exchangers 6 and 7 in figure 2), using as a heat source to extract unreacted isobutylene in the organic layer obtained by condensation and phase separation of the reaction distillation gas by distillation (for example, the heat source in the heat exchanger 11 in figure 2) and the like, using as a heat source for vaporization in the heat of the reaction distillation gas with water, the use of reactive distillation gas as a heat source for the distillation reboiler the column used for the extraction of isobutylene, extracting, tert-butanol or extraction or purification of isoprene by direct introduction of gas in the reboiler, etc. In figure 2, the water vapor produced by the heat exchanger 5 may be used in which the quality of steam for heating in the heat exchanger 11, etc.

To regulate the concentration of high boiling point byproducts in the reaction mixture with a hit in the interval of 0.5-40 wt.% the present invention includes a stage of continuous or intermittent introduction of the reaction mixture in the apparatus for decanting, extraction column, etc. and removing at least part of the high-boiling by-products from the reaction mixture, as described above.

As the method of removing high-boiling by-products is important in the present invention, the authors conducted an additional study of the invention. It was established that some of the accumulated by-products having high boiling point, have a high relative density in comparison with the reaction mixture, while others have a low relative density in comparison with the reaction mixture, as described above, and in the reactor high-boiling by-products, which have high relative density in comparison with the reaction mixture, tend to be in the lower part of the reaction mixture, namely at the bottom of the reactor, and high-boiling by-products that have a low relative density, tend to be in the upper part of the reaction mixture.

In a preferred embodiment of the present invention, therefore, the issue for the selection of the reaction mixture the location is, at least, in the bottom of the reactor for removal of high-boiling by-products from the reaction mixture. In figure 1, for example, the pipe P3 to select the reaction mixture is provided in the center of the bottom of the reactor. When using this pipeline P3 high-boiling by-products, which have high relative density in comparison with the reaction mixture, can be easily removed from the reactor, when a portion of the reaction mixture is continuously or periodically withdrawn. Although the release, preferably located in the center of the bottom of the reactor, it is not limited to this position, and one or more releases may be formed in the regulations (regulations), low enough for the selection of high-boiling by-products, which have high relative density in comparison with the reaction mixture.

Similarly, in the preferred embodiment of the present invention to facilitate the selection of high-boiling by-products that have a low relative density in comparison with the reaction mixture, the release for the selection of the reaction mixture is formed on the side wall of the reactor (the side wall of the reactor vessel). In this case, the level of release set so that the volume of the reaction mixture is filled up to a level that is not less than 1/2, more preferably not less than 2/3 of the total volume of the reaction mixture to the St must provide the start time of receipt (hereinafter abbreviated as marked as the height (h). At the location of the release for the selection of the reaction mixture at a specified height h of the high-boiling by-products that have a low relative density in comparison with the reaction mixture, can be easily removed, when a portion of the reaction mixture continuously or periodically extracted.

When education issues for the selection of the reaction mixture on the bottom and on the side wall of the reactor high-boiling by-products can be efficiently removed from the reaction mixture in the reactor despite the relative density and concentration of high-boiling by-products can more easily be adjusted to hit the interval of 0.5-40 wt.%.

When even a single issue for the selection of the reaction mixture is not formed in the bottom of the reactor, the high-boiling by-products, which have high relative density in comparison with the reaction mixture, accumulate at the bottom of the reactor during the reaction for a long time, and it becomes difficult to regulate the concentration of high boiling point byproducts in the reaction mixture with a hit in the interval of 0.5-40 wt.%. Then we have the problem of the deterioration in the efficiency of heating of the reaction mixture and clogging of pipelines, as well as the inability to maintain a steady state response due to fluctuations in the concentration of the acid and the ratio of the composition is as starting materials in the reaction mixture, etc.

In addition, when the release for the selection of the reaction mixture is not formed on the side wall of the reactor, the high-boiling by-products that have a low relative density in comparison with the reaction mixture, accumulate in the upper part of the reaction mixture during the reaction for a long time and becomes difficult to regulate the concentration of high-boiling by-products to hit the interval of 0.5-40 wt.%. Then limited to distillation of the resulting isoprene, water, unreacted starting materials and other low-boiling components as a reaction distillation gas from the reaction mixture outside of the reactor and has a problem of inability to maintain a steady state response due to the high level of the reaction mixture in the reactor and fluctuations of the concentration of the acid and the ratio of the composition of the starting materials in the reaction mixture, etc. in Addition, when the number of reaction distillation gas is reduced, the amount of aqueous solution of formaldehyde fed to the reactor should be reduced to maintain the reaction mixture in the reactor, which in turn reduces the amount of isoprene.

One preferred design of reactor regulation of the concentration of high-boiling by-products in the reaction mixtures and with a hit in the interval of 0.5-40 wt.%. described using Fig 1. Mixing device (external cause the device not shown) is set so that the agitating blade W rotates horizontally in the reaction mixture in the reactor, the P6 pipeline to supply With4goes right below the mixing blades in the reactor, and C4preferably served with a sprinkling to mixing blades from the inlet P6-1.

The distance between the mixing blade and the inlet supply With4not limited in the strict sense, if a4contact with the mixing blade; from the point of view of efficiency of the dispersion, for example, when the distance from the center of rotation of the mixing blades to the end is 2 m, the distance is usually preferably in the range of not more than 0.3 m, more preferably in the range of not more than 0.2 When m4served without contact with the mixing blade, the dispersion of gas and liquid in the reaction mixture becomes insufficient, the amount of high-boiling by-products is increased, and the concentration of high-boiling by-products accumulated in the reaction mixture tends to increase.

Although the shape of the inlet P6-1 for filing With4not specifically limited, in the preferred embodiment, the tube constituting the inlet P6-1, eshibits is like the ring, and a number of holes for filing With4performed on its circumference with suitable intervals. In this case, the annular inlet P6-1, preferably has a radius of curvature 50-80% of the distance between the center of rotation of the mixing blades and the end. Additionally, the spacing of holes formed on the circumference of the annular inlet P6-1 is, preferably, a distance corresponding to about 1/5-1/100 circumference, more preferably about 1/10-1/40 of the circumference.

As indicated above, preferably With4in the reaction mixture, heating the mixture with the use of the outdoor heat exchanger and return the mixture back into the reactor in the process of circulation of the reaction mixture between the reactor and the external heat exchanger (pipelines P7, P8, P9 figure 1).

In a preferred embodiment, returning the reaction mixture in the reactor, for example, the reaction mixture after introduction4and heating in the heat exchanger 3 is introduced into the lower part of the reactor by pipe P9 and served so that it comes into contact with the mixing blade W, as shown in figure 1. Thus, the gas and liquid in the reactor are dispersed enough, the increase in the concentration of high-boiling by-products can be suppressed and the concentration of high-boiling by-products can be easily adjusted. Here the lower h the b reactor is not specifically limited, if the reaction mixture is in contact with the mixing blade with the introduction of the reaction mixture again into the reactor. Preferably, it is introduced into the reactor from the bottom side of the mixing panel.

When the reaction mixture is returned to the reactor from the outdoor heat exchanger pipeline P9, not served in such a way that it comes into contact with the mixing blade, the gas and liquid in the reaction mixture in the reactor are not dispergirovannykh, the amount of high-boiling by-products increases and by-products accumulate in the reactor, which leads to a tendency to increased concentration of high-boiling by-products in the reaction mixture.

In the present invention, the water obtained by fractional condensation of the reaction distillation gas, can be used as the water fed to the reactor (hereinafter water, fractional condensed from the reaction distillation gas, and reusable, abbreviated specified as "circulating water"). For example, in figure 2 the water fraction condensed in the heat exchanger 5, is introduced into the collection of the distillate 8, is fed into the reactor through a pipeline P10-1 and re-used.

When you direct the circulating water in the reactor, the amount of the reaction mixture in the reactor can be maintained at a constant ur the outside, and the concentration of high boiling point byproducts in the reaction mixture can be easily adjusted with a hit in the interval of 0.5-40 wt.%. As the temperature of the circulating water is in the range of 120-140° (provided that a pressure of about 1.5 MPa), the amount of heat necessary for the production of isoprene, can be reduced. When the circulating water is not in use or when used fresh water (usually about 25°C), then may be regulated by the concentration of high boiling point byproducts in the reaction mixture, it is economically disadvantageous because the amount of heat required to heat the reaction mixture increases.

Isoprene can be obtained by fractionation of the organic substance layer, distilled outside the reaction system in the present reactionary way. Under the limit the separation of isoprene from the distillate, distilled through the pipeline P2 in figure 1, are known with reference to the well-known technology (for example, JP-A-60-4138 etc).

The present invention is explained hereinafter in detail with reference to examples, which are not intended to limit.

In the following examples, the equipment necessary for the implementation of the method of producing isoprene present invention, it was actually constructed, the concentration of high-boiling poboon the x products in the reaction mixture is controlled so as to be stable at various concentrations in the range of 0.5-40 wt.%, the reaction is carried out for 8 hours while maintaining the concentration at each level and to explore the transformation of formaldehyde, selectivity and yield of isoprene during the last 1 h at each concentration.

In comparative examples, the concentration of high boiling point byproducts in the reaction mixture in the reactor is set at the level beyond the above intervals, and a critical concentration of a number of high-boiling by-products is confirmed by comparison with example.

Example

Construction equipment

First one variant of the equipment designed for the method of obtaining of the present invention, is illustrated in figure 2.

Capacity (internal volume of 120 l) was prepared as a reactor 1, is attached to the P6 pipeline for introduction4the pipeline P1-1 for introducing an aqueous solution of formaldehyde, the pipeline P1-2 for the introduction of water, the pipe P1-3 for the introduction of the acid aqueous solution (aqueous solution of phosphoric acid), distillation pipeline P2 for products, etc. and the pipes P3 and P4 for the selection of the reaction mixture. The reactor is equipped with auxiliary devices necessary to control the reaction, such as a thermometer, a pressure sensor, mesh is ka, reflector, etc.

In the reactor 1 serves 46 wt.% an aqueous solution of formaldehyde, 2.5% aqueous solution of phosphoric acid as the acidic aqueous solution and 12-times the number of moles of water with respect to formaldehyde. On the other hand, 8 is a multiple of the number of moles4in relation to formaldehyde is preheated in the heat exchanger 2 with the inclusion of evaporation and serves, when spraying With4to the mixing blades in the reactor of an annular inlet for the filing of a4.

In addition, use a construction in which the pipe P7 branches off from the pipe P3 to filter the reaction mixture, the reaction mixture taken from the reactor, mixed with4, the resulting mixture is heated in the heat exchanger 3 and return to the reactor. The reaction mixture is heated in the heat exchanger 3, spray to the mixing blades from contact with the blade when it is returned to the reactor 1.

Isoprene obtained in the reactor 1, is distilled outside of the reactor as the reaction distillation gas pipeline P2 together with unreacted4, water, formaldehyde, etc. of the Reaction distillation gas is fed into the heat exchanger 5. In the heat exchanger 5 is the heat exchange between the reaction distillation gas coming down the pipeline for heat, and cold water running in the heat is obmennik (or reaction distillation gas is cooled), therefore, the water in the reaction distillation gas fraction is condensed. In addition, the cooling water that flows in the heat exchanger 5 becomes the ferry with the amount of heat obtained from the reaction distillation gas, so the amount of heat accumulates.

The water fraction condensed in the heat exchanger 5 serves in the collection of the distillate 8.

Part of the water in the collection of the distillate 8 directly fed into the reactor through a pipeline P10-1, used for controlling the amount of the reaction mixture in the reactor is also fed into the heat exchanger 2 through the pipe P10-2 used to adjust the molar ratio of formaldehyde and C4that is evaporated together with4and fed into the reactor 1. The remaining water in the collection of the distillate 8 served in the collection of the distillate 9.

On the other hand, a connection that has not been condensed in the heat exchanger 5, is condensed in the heat exchangers 6 and 7 served in the collection of the distillate 9, where it is separated into an organic layer and an aqueous layer. The organic layer is fed into the heat exchanger 7, is heated and fed to a distillation column 10 for the separation of isobutylene.

Fraction in the distillation column 10 mainly contains isobutylene, which is condensed in the heat exchanger 12 and is served in the collection of the distillate 13.

Part of the fraction containing isobutylene in the quality of the ve main component, heated in heat exchanger 6 to ensure evaporation, part of it is fed into the heat exchanger 2 for regulating the molar ratio with formaldehyde, and the other part is fed into the heat exchanger 3 to prevent elevation of boiling point in the heat exchanger 3 and then returned to the reactor 1. The remaining fraction is returned to the distillation column 10 or separately reused as a starting material for the method of producing the present invention by the stage of purification of isobutylene.

CBM solution distillation column 10 contains the unreacted isoprene and tert-butanol as the major components. Isoprene is obtained from the upper part of the column during the purification of this solution of the cubic distillation column 10 to a distillation column 14.

The main component of the cubic solution in the distillation column 14 is tert-butanol, which separately purified and reused in the production method of the present invention. By-product obtained in this case, served in the capacity of branch of high-boiling by-products 4 and is used as an extraction solvent for the separation of high-boiling by-products from the reaction mixture taken from the reactor.

The reaction mixture (including high-boiling by-products) in the reactor 1 is selected the C of each issue for the selection, formed in the center of the bottom of the reactor and on the side walls near the level of the reaction mixture, and after mixing with the above-mentioned extraction solvent is served in the capacity of branch of high-boiling by-products 4 where it is separated into the organic layer (extraction solvent)containing high-boiling by-products, and aqueous layer.

The organic layer is effectively used for fuel and the like, and at least part of the aqueous solution of phosphoric acid in the aqueous layer is recycled to the reactor.

The reaction mixture may be selected as samples for measuring the concentration of high boiling point byproducts in the reaction mixture in the reactor, for example, in the formation of editions for selection in the pipes P3, P4 and P7. In your design, the reaction mixture may be selected or may be selected from the editions of regulation in the concentration of high boiling point byproducts in the reaction mixture with a hit in the interval of 0.5-40 wt.% upon confirmation of their concentration.

Examples 1-8

The reaction conditions in the reactor are as follows: the reaction temperature 175-178°C, pressure of the reaction of 1.52 MPa and the rotation speed of the stirring blades 48-55 rpm

Into a reactor (internal volume of 120 l) load a 2.5% aqueous solution of phosphoric acid (60 l) and there is continually serves 46 m is S.% aqueous solution of formaldehyde with a speed 3,24 kg/h, isobutylene with a speed of 17.7 kg/h of tert-butanol with a rate of 6.02 kg/h and the water with the speed of the remaining 9.08 kg/h in the above reaction conditions from the beginning of the reaction.

After 24 h after start of the reaction the concentration of high boiling point byproducts in the reaction mixture to regulate the below specified values by regulating the number of remote high-boiling by-products in the vessel branch of the high-boiling by-products 4 in the reaction equipment, shown in figure 2, in which one issue for the selection of the reaction mixture is in the center of the bottom of the reactor and one issue is formed on the side (at the level corresponding to 4/5 of the full volume of the reaction mixture in the reactor), With4sprayed from the inlet P6-1 for introduction by contact with the mixing blades, when the reaction mixture is returned to the reactor through a pipeline P9, it is sprayed with contact with mixing blades, and circulating water is introduced again into the reactor from the collection of the distillate 8.

Adjustable concentration regulated by-products having high boiling point, are as follows: 0.5% (example 1), 1 wt.% (example 2), 2 wt.% (example 3), 5 wt.% (example 4), 10 wt.% (example 5), 20 wt.% (example 6), 30 wt.% (example 7), 40 wt.% (example 8).

The reaction is maintained at steady state at each concentric is and and is then continued for 8 hours The degree of conversion of formaldehyde, selectivity and yield of isoprene examined in the last 1 h the Results are shown in the table.

Comparative examples 1-4

The reaction is carried out in the same manner as in examples 1-8, except that the concentration of by-products having high boiling point, the reaction mixture is set at 0 wt.% (comparative example 1), 0.3 wt.% (comparative example 2), 50 wt.% (comparative example 3) and 60 wt.% (comparative example 4), the degree of conversion of formaldehyde, selectivity and yield of isoprene examined in the last 1 h the Results are shown in the table.

The concentration of high-boiling by-products (wt.%)The degree of conversion of formaldehyde (%)The isoprene selectivity (%)Output (%)
Example10,598,172,471,0
21of 98.272,471,2
3298,372,571,4
4598,372,771,5
51098,372,871,9
62098,573,071,6
73098,672,571,3
84098,872,371,0
Comparative example10,195,872,269,2
20,396,772,369,9
35095,970,067,1
46095,768,565,6

Every reaction is carried out in accordance with examples 1-8 and comparative examples 1-4. As can be seen from the table, in the reactor can be maintained at a steady state of the reaction, the degree of conversion of formaldehyde is always not less than 98% and the yield of isoprene is always no less than 71% while maintaining the concentration of high boiling point byproducts in the reaction mixture in the range of 0.5-40 wt.% (examples 1-8).

On these results, it was established that isoprene can be efficiently obtained while maintaining the steady state of the reaction by maintaining the concentration of high boiling point byproducts in the reaction mixture in the range of 0.5-40 wt.%.

On the contrary, in comparative the x examples 1-4, where the concentration of high boiling point byproducts in the reaction mixture is outside the above range, the degree of conversion of formaldehyde is below 97%, and the yield of isoprene is always less than 70% in all examples.

In addition, in comparative examples 1 and 2, where the concentration of high boiling point byproducts in the reaction mixture is less than 0.5 wt.%, the efficiency of heating the reaction mixture in the heat exchanger 3 is reduced, resulting in a lower temperature of the reaction mixture in the reactor, which, in turn, reduces the degree of conversion of formaldehyde, and the output becomes smaller.

In comparative examples 3 and 4, where the concentration of high-boiling by-products is set at a value exceeding 40 wt.%, high-boiling by-products accumulate in the piping connecting the reactor 1 and the heat exchanger 3, and the flow of the reaction mixture in the heat exchanger 3 becomes difficult, which, in turn, gives the low efficiency of heating the reaction mixture in the heat exchanger 3. Therefore, the temperature of the reaction mixture in the reactor is reduced, which, in turn, reduces the degree of conversion of formaldehyde and isoprene selectivity, and the output becomes smaller.

A method of producing isoprene present invention has the advantage that the stage are PR is stimi, and, in addition, can be reduced to low efficiency in comparison with other known methods for producing isoprene (for example, JP-A-56-79628 and HYDROCARBON PROCESSING, p. 167, November, 1971). Successful increase of approximately 2% in this way that could not be achieved so far, is highly useful in the technical field of the present invention from the point of view of cost.

Industrial applicability

Isoprene obtained by the method of obtaining the present invention can be effectively used as a basic chemical raw material for various chemicals and polymeric materials.

1. A method of producing isoprene in a single phase, which contains continuous or periodic supply of isobutylene and/or tertbutanol, formaldehyde and water in the acid aqueous solution and the interaction of the reaction mixture during the distillation of a mixture containing the resulting isoprene, water, unreacted starting materials and other low-boiling components from the specified reaction mixture outside the reaction system, in which this reaction is carried out under the regulation of the concentration of high-boiling by-products, which are produced and accumulate in the specified reaction mixture, with a hit in the interval of 0.5-40 wt.%.

2. The method according to claim 1, in which the concentration of high-boiling poboc who's products in the reaction mixture regulate to hit the specified interval education edition/editions for selection of the reaction mixture from the reactor, containing the reaction mixture, the selection of the reaction mixture from the release and separation and removal of at least part of the high-boiling by-products from the reaction mixture, followed by introduction of the remaining reaction mixture again into the reactor.

3. The method according to claim 2, in which the release for the selection of the reaction mixture include, at least, in the bottom of the reactor.

4. The method according to claim 2, in which the release for the selection of the reaction mixture is placed in the side wall of the reactor, and the release level set so that the volume of the reaction mixture is filled up to a level that is not less than 1/2 of the total volume of the reaction mixture in the process of producing isoprene.

5. The method according to claim 2, in which the release for the selection of the reaction mixture is placed in the bottom of the reactor and another release for the selection of the reaction mixture is placed in the side wall of the reactor, and the release level set so that the volume of the reaction mixture is filled up to a level that is not less than 1/2 of the total volume of the reaction mixture in the process of producing isoprene.

6. The method according to claim 1, in which the mixture containing the resulting isoprene, water, unreacted starting materials and other low-boiling components are distilled off from the reaction system as the reaction distillation gas, water fractional condensation of the reaction distillation gas and the resulting water is injected again in the region of the actor to control the concentration of high boiling point byproducts in the reaction mixture with a hit in a given interval.

7. The method according to PP. 2, 3, 4 or 5, in which the mixture containing the resulting isoprene, water, unreacted starting materials and other low-boiling components are distilled off from the reaction system as the reaction distillation gas, water fractional condensation of the reaction distillation gas and the resulting water is injected back into the reactor to control the concentration of high boiling point byproducts in the reaction mixture with a hit in a given interval.

8. The method according to claim 1, in which the concentration of high boiling point byproducts in the reaction mixture regulate to hit the specified interval by setting the reactor mixing device having a mixing blade that is designed for horizontal rotation in the reaction mixture in which part of the reaction mixture withdrawn from the reactor, is heated, at least a part of isobutylene and/or tertbutanol in the heat exchanger and is introduced again into the reactor, and supplying heated the reaction mixture to a mixing blades from the inlet formed in the reactor.

9. The method according to PP. 2, 3, 4, 5 or 6, in which the concentration of high boiling point byproducts in the reaction mixture regulate to hit the specified interval by setting the reactor mixing device having a mixing blade, designed for horizontal the CSOs rotation in the reaction mixture, in which part of the reaction mixture withdrawn from the reactor, is heated, at least a part of isobutylene and/or tertbutanol in the heat exchanger and is introduced again into the reactor, and supplying heated the reaction mixture to a mixing blades from the inlet formed in the reactor.

10. The method according to PP. 2, 3, 4, 5, 6 or 8, in which the concentration of high boiling point byproducts in the reaction mixture regulate to hit the specified interval by setting the reactor mixing device having a mixing blade that is designed for horizontal rotation in the reaction mixture in which part of the reaction mixture withdrawn from the reactor, is heated, at least a part of isobutylene and/or tertbutanol in the heat exchanger and is introduced again into the reactor, and supplying heated the reaction mixture to a mixing blades from the inlet formed in the reactor.



 

Same patents:

FIELD: chemical industry; methods of production of the pure isobutene out of the isobutene-containing mixture.

SUBSTANCE: the invention is pertaining to the method of production of the pure isobutene out of the isobutene-containing mixture predominantly - out of hydrocarbon С4 with usage of the catalysis by the strong-acid cationite(s) including the liquid-phase interaction of the isobutene with the water at the temperature of from 60 up to 130°С in one or several sections at the stage of hydration, delamination of the being withdrawn from it stream(s), distillation of the unreacted hydrocarbons С4 from the hydrocarbon layer, decomposing of the tret-butanol in the section(s) at the stage of dehydration, separation of the formed isobutene from the water and its) purification and characterized by that isobutene and the total amount of the returned from the stage of dehydration fresh water is fed in the section of hydration in the total molar ratio from 1:0.4 up to 1:20, and it is preferential from 1:1 up to 1:5, in the straight-flow or bubbling mode in the absence of the emulsifier hydrate from 30 up to 97 % of isobutene. From the stage of the hydration in the stage of the dehydration at least one-third of the produced tret-butanol is fed in the stream, separated by the rectification from the layer of the unreacted hydrocarbons and containing from 5 up to 30 mass % of the water, and, possibly, the rest amount - in the stream of the water layer, at the total content of the different, than the isobutene, the hydrocarbons not exceeding their admissible quantity in the target isobutene, and from the stage of the dehydration the water at least partially is returned into the stage of the hydration. The presented method requires the low power input and the low metal input.

EFFECT: the invention ensures the low power input and the low metal input.

14 cl, 2 dwg, 4 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of styrene. At the first step the method involves interaction of ethylbenzene hydroperoxide with propene in the presence of catalyst to yield propylene oxide and 1-phenylethanol followed by separate treatment of reaction flow and removing propylene oxide. At the second step the method involves interaction of 1-phenylethanol-containing distillate with a heterogenous dehydration catalyst at temperature 150-320°C to obtain styrene. Distillate contains 0.30 wt.-%, not above, compounds of molecular mass at least 195 Da. Invention provides decreasing the content of by-side compounds in styrene and to enhance it's the conversion degree.

EFFECT: improved method of synthesis.

3 cl, 3 tbl

FIELD: industrial organic synthesis and catalysts.

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4 cl, 5 tbl, 18 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of alkylaryl hydroperoxides useful as starting material in production of propylene oxide and alkenylaryl. Process of invention comprises following stages: oxidation of alkylaryl compound to form reaction product containing alkylaryl hydroperoxide; contacting at least part of reaction product with basic aqueous solution; separation of hydrocarbon phase containing alkylaryl hydroperoxide from aqueous phase; containing at least part of above hydrocarbon phase with aqueous solution containing waste water, said aqueous solution containing less than 0.2% alkali metal and/or salt (determined as ratio of metal component to total amount of solution); and separation of hydrocarbon phase from aqueous phase. By bringing at least part of above hydrocarbon phase containing alkylaryl hydroperoxide into interaction with propylene and catalyst, alkylaryl hydroxide and propylene oxide are obtained. At least part of propylene oxide is then separated from alkylaryl hydroxide. Dehydration of at least part of alkylaryl hydroxide results in formation of alkenylaryl.

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8 cl, 4 ex

FIELD: industrial organic synthesis.

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5 cl, 14 ex

The invention relates to a method for producing olefin vapor-phase dehydration of alcohols in the presence of a catalyst at elevated temperature

The invention relates to methods for production of 1-butanol (options), 1,3-butadiene and high-octane fuel from ethanol
The invention relates to the petrochemical industry and can be used to obtain propylene oxide (OP) and styrene

The invention relates to the field of production of isoprene and monovinylacetylene monomers
The invention relates to the petrochemical industry and can be used in the process of joint production of propylene oxide and styrene

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to an isoprene production process involving dehydrogenation of isoamylene fraction in presence of overheated steam and iron oxide-based catalyst and is characterized by that catalyst has loose density at least 1.0 g/cc and not higher than 2.00 g/cc, apparent density at least 2.0 g/cc and not higher than 3.5 g/cc, and following composition. wt %: potassium compound 5-30, magnesium oxide 0.5-10, cerium(IV) oxide 5-20, calcium carbonate 1-10, molybdenum oxide 0.5-5, and ferric oxide - the rest.

EFFECT: improved selectivity of dehydrogenation process and increased activity and service cycle of catalyst.

2 cl, 1 tbl, 7 ex

FIELD: petrochemical processes.

SUBSTANCE: isoprene is obtained from isobutylene-containing stream and formaldehyde. Process comprises at least zones for chemical conversion in presence of strong-acid catalyst(s) and water and zone(s) for separating resulting mixtures. At least one of zones is used to carry out liquid-phase synthesis of intermediates suitable to be converted into isoprene, in which process unconverted C4-hydrocarbons are preferably separated and stream containing these intermediates are subjected to joint processing in vertical intermediate conversion zone(s) to produce isoprene preferably at ascending travel of stream(s). Converted vapor stream picked from the top of the conversion zone chiefly contains isoprene and isobutylene, and partially water. The stream is separated to remove at least one liquid stream containing chiefly water and optionally acid and organic impurities. This stream freed of high-boiling by-products (capable of being densified) is recycled to synthesis zone(s) and/or intermediate conversion zone(s). Resulting liquid organic stream contains high-boiling by-products, major part of which are separated inside intermediate conversion zone(s) and/or in a separate outer zone by way of extraction at 65 to 170°C with organic solvent containing essentially no alkadienes and components forming azeotropes with isoprene, which solvent is unable of forming homogeneous mixture with the above stream supplied in amount large enough to extract most part of high-boiling by-products. After extraction and settling, low layer is recycled to intermediate conversion zone(s) and optionally partially to intermediate synthesis zone(s).

EFFECT: alleviated clogging of equipment and reduced power consumption.

14 cl, 1 dwg, 7 ex

FIELD: industrial organic synthesis.

SUBSTANCE: in two-stage isoprene production process via dehydration of isopentane, contact gas produced in each stage is condensed and non-condensed hydrocarbons are absorbed and then desorbed. Hydrocarbon condensate is separated by rectification to give low-boiling hydrocarbon distillate fraction and bottom product. The latter is separated with the aid of extractive rectification to give isopentane and isoamylene fractions after the first dehydration stage and isoprene and isoamylene fractions after the second dehydration stage. Non-condensed low-boiling hydrocarbon vapors recovered after rectification are combined with non-condensed hydrocarbons from the first dehydration stage, preliminarily compressed, separated, and subjected to absorption.

EFFECT: maximized utilization of C5-hydrocarbons leading to reduced consumption of isopentane.

2 dwg, 4 tbl

FIELD: industrial organic synthesis.

SUBSTANCE: isoprene is produced from isobutene contained in C4-hydrocarbon fraction and formaldehyde in presence of water acid catalyst corrosive or moderately corrosive toward alloyed steel. Process is accomplished in at least two stages of liquid-phase chemical conversion to form, in the intermediates synthesis stage, isoprene precursors and withdrawing them with organic and essentially water stream followed by distillation of at least C4-hydrocarbons from organic stream and joint processing of the rest of organic stream and above-mentioned essentially water stream in intermediates decomposition stage. Decomposition of intermediates is accompanied by continuous withdrawal of vapor stream containing isoprene, isobutene, and a part of water, which stream is further subjected to separation and removal of liquid stream containing essentially water and acid and, preferably, removal of liquid organic stream containing high-boiling by-products. At least part of isobutene isolated from decomposition stage products is recycled into the beginning of this stage in such an amount that, in this stage, input streams contain summary molar amount of isobutene and tert-butanol exceeding by 1.1 times, preferably by 1.4 times, summary molar amount of formaldehyde and 4,4-dimethyl-1,3-dioxane. Organic stream obtained after condensation and stratification of vapor stream from decomposition stage is brought into contact with liquid stream from decomposition stage containing mainly water and acid and then subjected to separation involving at least rectification step, and stream containing mainly water and acid is recycled into the beginning of decomposition and/or synthesis stage.

EFFECT: simplified technology and reduced formation of high-boiling by-products.

2 cl, 2 dwg, 3 ex

FIELD: technology of petroleum chemistry, organic chemistry.

SUBSTANCE: invention relates to a method for preparing isoprene, isobutylene and formaldehyde from by-side products in the process for producing isoprene. Methyldihydropyrane and/or high-boiling products are heated in the presence of steam up to temperature 400-550°C followed by their contacting with alumosilicate-containing catalyst in the presence of steam at temperature 400-480°C. Method provides enhancing the selectivity of process, to enhance the conversion of heavy residue and to reduce the coke deposition. Invention can be used in industry of synthetic rubber and the organic synthesis.

EFFECT: improved processing method.

2 cl, 1 tbl, 4 ex

FIELD: petroleum chemistry, chemical technology.

SUBSTANCE: invention relates to dehydrogenation of isoamylenes to isoprene on iron oxide self-regenerating catalysts. Method involves addition of piperylenes in the concentration up to 4 wt.-% representing a by-side product in manufacturing process of isoprene by the indicated method to the parent isoamylenes before their dehydrogenation. Method provides enhancing selectivity of method for isoamylenes dehydrogenation to isoprene in the presence of iron oxide self-regenerating catalysts.

EFFECT: improved preparing method.

1 tbl, 6 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

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: 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: 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

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