JP5614618B2 - Manufacturing method of ETBE - Google Patents

Description

  The present invention relates to a method for producing ETBE, and more specifically, relates to a method for producing ETBE, which enables high-purity ETBE to be obtained in a high yield by a simple method, and enables the apparatus to be enlarged and put into practical use.

Ethyl tertiary butyl ether (hereinafter referred to as “ETBE”) has a high octane number (octane number: 118) and is stable in quality because it is hardly soluble in water. For this reason, ETBE is expected as a fuel for global warming countermeasures.
In recent years, ETBE has already been put into practical use in Europe and the United States (particularly Europe) as an alternative fuel for gasoline, in particular, high-octane fuel, or an additive for these fuels, and introduction into the country is also being studied. In France and Spain, ETBE is used by adding about 15% to gasoline.
ETBE is also attracting attention as a substitute for the fuel additive methyl tertiary butyl ether, which has been suspended in Japan since 2004 due to suspicion of carcinogenicity.

Such ETBE is generally produced by reacting ethanol and isobutene in the presence of a catalyst.
For example, as a method for extracting ETBE, a method for separating ethyl tert-butyl ether (see, for example, Patent Document 1 or 2) for separating ETBE from an ethanol-ETBE mixture using water is known, and synthesis of ETBE is known. As a method, a tertiary ether production method (for example, see Patent Documents 3 to 5) that performs two-stage extractive distillation, a purification method for ethyl tertiary butyl ether that combines a thin film method and distillation (for example, see Patent Document 6). ), A synthesis method (for example, see Patent Document 7) that eliminates the need for dehydration of ethanol by providing a water washing tower, a method for producing an alkyl ether using microwaves (for example, see Patent Document 8), and the like. ing.

  For reference, a method for producing ETBE from ethanol and tertiary butyl alcohol is disclosed (see, for example, Patent Document 9 or 10).

Japanese Patent Laid-Open No. 5-65241 JP-A-5-201906 JP 7-149681 A JP-A-7-304703 JP 2007-182441 A JP 7-278035 A JP 2006-151869 A JP 2008-133250 A JP-A-7-149682 JP 2007-126450 A

However, the methods for separating ethyl tert-butyl ether described in Patent Documents 1 and 2 add complexity to the system and increase the cost due to the addition of water. Further, rust and the like due to water are generated in the device, and the life of the device tends to be shortened.
Although the tertiary ether production methods described in Patent Documents 3 to 5 perform two-stage extractive distillation, the yield of ETBE is insufficient. Further, in the method for purifying ether described in Patent Document 4, the number of necessary distillation towers is increased, the apparatus cost is enormous, and practical application is difficult. Furthermore, in the manufacturing method of ETBE described in Patent Document 5, the UNIFAC method based on an atomic group contribution method that is an estimation method and the Peng-Robinson (Peng-Robinson equation of state) equation that is a van der Waals type equation of state that does not depend on pressure Since the calculation of the system construction is performed using, the calculation result may be uncertain and it is difficult to put the device into practical use.
The method for purifying ethyl tert-butyl ether described in Patent Document 6 has a drawback that it is difficult to scale up because it uses a thin film method.
In the method of synthesizing ETBE described in Patent Document 7, since the C4 component is liquefied at room temperature, it is necessary to increase the size of the tubular reaction vessel provided with the catalyst packed layer and the cushion layer, and the cost also increases. It is difficult to put the device into practical use.
In the method for producing an alkyl ether described in Patent Document 8, it is difficult to increase the size of the apparatus.

  The present invention has been made in view of the above circumstances, and provides a method for producing ETBE capable of obtaining high-purity ETBE in a high yield with a simple method and capable of upsizing and practical use of the apparatus. With the goal.

  The present inventors have intensively studied to solve the above-mentioned problems. As a result, the present inventors have found that the above-mentioned problems can be solved by reactive distillation of the residue after the reactive distillation step under a predetermined high-pressure condition, thereby completing the present invention. It came to.

That is, the present invention includes (1) a dehydration step in which water mixed in ethanol is made to have a water concentration of 3000 ppm or less using a water adsorbent , a hydrocarbon containing isobutene and ethanol as a reaction catalyst. The main reaction step to be reacted below, the mixture is further reactively distilled in a distillation tower to obtain ETBE, the residue in the reactive distillation step is reactively distilled under high pressure conditions, and the ETBE distillation step to obtain ETBE, The ethanol is obtained by hydrolyzing lignocellulose into sugar and fermenting the sugar. The main reaction step is performed by a pressurized gas-liquid mixed phase reaction method, and the reactive distillation step is a reactive distillation method. in resides in the method of manufacturing the decorated with Ru ETBE.

  The present invention resides in (2) the method for producing ETBE according to the above (1), wherein the high-pressure condition in the ETBE distillation step is greater than 0.23 MPa.

  The present invention resides in (3) the method for producing ETBE according to the above (1), wherein the hydrocarbon further comprises at least one selected from the group consisting of propane, isobutane, 1-butene, 2-butene and pentane.

The present invention (4) in the dehydration step, consists in ETBE method according to any one of the above you dehydration temperature 20~200 ℃ (1) ~ (3 ).

The present invention, (5) reaction catalyst, Ri strongly acidic cation exchange resin der made of a porous type styrene resin strong acid group is introduced as the ion exchange group, the particle size of said strong acid cation exchange resin was a 0.5 to 1.0 mm, the amount of reaction catalyst, with respect to ethanol 1 mole, the shall be the 1~90g (1) ~ (4) a method of manufacturing a ETBE according to any one of Exist.

The present invention (6) and carbonizing the isobutene concentration in the hydrogen 5% by weight or more, you the molar ratio of isobutene to ethanol of the material and 0.1 to 10 moles of (1) to any one of (5) ETBE manufacturing method described in 1.

  The present invention provides (7) production of ETBE according to any one of (1) to (6) above, wherein ETBE having a purity of 95% by weight or more is discharged under a temperature condition of 100 ° C. or lower in a reactive distillation step. Lies in the way.

According to the present invention, (8) in a pressurized gas-liquid mixed phase reaction system, the reaction temperature is set to 100 ° C. or lower, the atmospheric pressure during the reaction is set to a pressure higher than that at which ethanol can maintain the liquid phase, and isobutene circulates in the gas phase. The method for producing ETBE according to any one of (1) to (7) above.

The present invention (9) In the pressurized gas-liquid mixed phase reaction method, the reaction pressure was more than 0.3 MPa, the liquid hourly space velocity 0.1 to 10 (m ³ - ethanol / hr / m ³ - catalyst) shall be the above (1) It exists in the manufacturing method of ETBE as described in any one of (8).

The present invention is (10) in the reactive distillation step, the temperature of the reactive distillation section of the distillation column is 100 ° C. or lower, the temperature of the top of the distillation tower is 30 to 80 ° C., and the temperature of the bottom of the distillation tower is 90 to 90 ° C. and 0.99 ° C., the column top pressure was 0.7MPa or less, you operated a reflux ratio of the distillation column such that 0.1 to 4 above (1) to the ETBE according to any one of (9) Lies in the manufacturing method.

In the (11) ETBE distillation step, the temperature at the top of the distillation column is set to 50 to 90 ° C., the temperature at the bottom of the distillation column is set to 130 to 180 ° C., and the pressure at the top of the distillation column is set to 0.1. greater than 23 MPa, consists in ETBE method according to any one of the above a purity of 95% or more by weight of ETBE Ru was issued can (1) to (10).

The present invention (12) and ETBE distillation step isobutene recovery step of recovering the unreacted isobutene from the residue in the ethanol recovery step of recovering the ethanol unreacted residue after isobutene recovery step, Ru further comprising the ( 1) It exists in the manufacturing method of ETBE as described in any one of (11).

The present invention (13) in isobutene recovery step consists in upper Symbol (12) SL mounting ETBE production method of you to the overhead pressure of the distillation column and 0.5～1.5MPa.

In the (14) ethanol recovery step, the present invention provides that the pressure at the top of the distillation column is normal pressure, the temperature at the top of the distillation column is 65 to 90 ° C, and the temperature at the bottom of the distillation column is 90 to 120 ° C. and then, after purity was distilled ethanol 96 wt% or less, subjected to a dehydration step of removing water are mixed in the ethanol, the production of ETBE described above you reuse (12) or (13) Lies in the way.

In the method for producing ETBE of the present invention, high-purity ETBE can be obtained with high yield by a simple method by including an ETBE distillation step performed under high-pressure conditions.
Moreover, since neither a reactive distillation process nor an ETBE distillation process requires a special apparatus, the apparatus can be enlarged and put into practical use. The pressure condition in the ETBE distillation step is preferably greater than 0.23 MPa.

  In the method for producing ETBE of the present invention, when the hydrocarbon is a mixed gas further containing at least one selected from the group consisting of propane, isobutane, 1-butene, 2-butene and pentane, ETBE is selectively and It can be manufactured efficiently.

  In the method for producing ETBE of the present invention, if a dehydration step for removing water mixed in ethanol is further provided before the reactive distillation step (or main reaction step), the yield of ETBE is further improved.

  In the ETBE production method of the present invention, when the reaction catalyst is a cation exchange resin, the reaction between isobutene and ethanol proceeds rapidly.

  In the method for producing ETBE of the present invention, when ethanol is obtained by hydrolyzing and fermenting lignocellulose, ETBE can be produced by a low-cost and low environmental load type process.

  In the method for producing ETBE of the present invention, ETBE can be efficiently obtained by allowing ETBE having a purity of 95% by weight or more to be taken out in a reactive distillation step under a pressure condition of 0.7 MPa or less.

  The ETBE production method of the present invention includes a main reaction step for reacting hydrocarbon and ethanol before the reactive distillation step, the main reaction step is performed by a pressurized gas-liquid mixed phase reaction method, and the reactive distillation step is a reaction. When applied by distillation, the yield of ETBE obtained is further improved. In the pressurized gas-liquid mixed phase reaction method, it is preferable that the reaction temperature is 100 ° C. or lower, the atmospheric pressure during the reaction is higher than the pressure at which ethanol can maintain the liquid phase, and isobutene circulates in the gas phase.

  In the method for producing ETBE of the present invention, when an ethanol recovery step and / or an isobutene recovery step are further provided, ethanol and / or isobutene can be efficiently recovered. The recovered ethanol and / or isobutene can be subjected to the above-described process again. In the ethanol recovery step, it is preferable to distill ethanol having a purity of 96% by weight or less from the top of the distillation column under normal pressure conditions. In the isobutene recovery step, isobutene is preferably recovered under a pressure condition of 0.5 to 1.5 MPa.

FIG. 1 is a flowchart showing a method of manufacturing ETBE according to this embodiment. FIG. 2 is a graph showing the relationship between the reaction temperature of the reaction for synthesizing ETBE from ethanol and isobutene and the equilibrium reaction rate of the ideal gas. FIG. 3A is a graph showing vapor pressure lines of ethanol and ETBE. FIG. 3B is a graph showing vapor pressure lines of ethanol and ETBE. FIG.3 (c) is a graph which shows the vapor | steam pressure line of ethanol and ETBE. FIG.3 (d) is a graph which shows the vapor | steam pressure line of ethanol and ETBE. FIG. 4 is a graph showing a vapor-liquid equilibrium line at normal pressure of ethanol and water. FIG. 5 is a flowchart showing a manufacturing method of ETBE in the embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

In the ETBE production method according to the present invention, assuming that the hydrocarbon containing isobutene is supplied from crude oil by a fluid catalytic cracker, the hydrocarbon components are isobutene, propane, isobutane, 1-butene, 2 -Butene and pentane.
In this case, the reaction related to the production of ETBE is represented by the following formulas (1) to (6).

・ Main reaction
(CH ₃ ) ₂ C = CH ₂ (V) + CH ₃ CH ₂ OH (L) → (CH ₃ ) ₃ COCH ₂ CH ₃ (L) + 56.8 kJ / mol (1)
-Side reaction 1 (0.25 mol% with respect to ethanol)
2CH ₃ CH ₂ OH (L) → H ₂ O (L) + (C ₂ H ₅ ) ₂ O (V) − 16.3 kJ / mol (2)
-Side reaction 2 (0.25 mol% with respect to isobutene)
(CH ₃ ) ₂ C = CH ₂ (V) + H ₂ O (L) → (CH ₃ ) ₃ OH (L) + 56.3 kJ / mol (3)
-Side reaction 3 (0.09 mol% with respect to ethanol including side reaction 4)
CH ₃ CH ₂ CH = CH ₂ (V) + CH ₃ CH ₂ OH (L) → CH ₃ CH ₂ (CH ₃ ) CHOCH ₂ CH ₃ (L) + 109.1 kJ / mol (4)
・ Side reaction 4
CH ₃ CH = CHCH ₃ (V) + CH ₃ CH ₂ OH (L) → CH ₃ CH ₂ (CH ₃ ) CHOCH ₂ CH ₃ (L) + 101.8 kJ / mol (5)
-Side reaction 5 (0.42 mol% with respect to isobutene)
2 (CH ₃ ) ₂ C = CH ₂ (V) → (CH ₃ ) ₃ CCH ₂ C (CH ₃ ) = CH ₂ (L) + 111.4 kJ / mol (6)
In the formulas (1) to (6), V represents a gas phase and L represents a liquid phase, the reaction heat is 25 ° C., the reaction heat plus (+) is an exothermic reaction, and minus (−) is an endothermic reaction. means.

Table 1 shows the standard boiling points of the above-described components and the standard heat of formation that is the basis of the heat of reaction.
[Table 1]

FIG. 2 is a graph showing the relationship between the reaction temperature of the reaction for synthesizing ETBE from ethanol and isobutene and the equilibrium reaction rate of an ideal gas. FIGS. 3 (a) to 3 (d) show the relationship between ethanol and ETBE. It is a graph which shows the vapor pressure line.
As shown in FIG. 2, in order to promote the main reaction (formula (1)), it is advantageous to perform the reaction at a low temperature and a high pressure, but each reaction has a limitation of reaction equilibrium.
The normal boiling points of isobutene, ethanol, and ETBE are −6.9, 78.3, and 72.8 ° C., respectively, as shown in Table 1, and the vapor pressures of ethanol and ETBE are shown in FIGS. d) intersect at 0.23 MPa, 102 ° C. and 0.1 MPa (66.3 ° C., ETBE molar fraction 0.65), 0.5 MPa (121.9 ° C., ETBE molar fraction 0) .5), 1.0 MPa (151.5 ° C., ETBE molar fraction 0.35), azeotrope exists.

From these facts, when ethanol and ETBE are distilled and separated at a vapor pressure of less than 0.23 MPa where the vapor pressures of ethanol and ETBE intersect, ETBE is distilled from the top of the column and azeotrope is taken out from the bottom of the column.
On the other hand, when distilling at a pressure greater than 0.23 MPa and having an azeotrope of ethanol and ETBE of about 1.3 MPa or less, ethanol is distilled from the top of the column, and azeotrope is removed from the bottom of the column. become.
In addition, when carrying out distillation separation at about 1.3 MPa or more without azeotropy, ethanol will be distilled from the tower top part, and ETBE will be taken out from the tower bottom part.

  From these things, an example of embodiment of the manufacturing method of ETBE concerning the present invention is shown.

FIG. 1 is a flowchart showing a method of manufacturing ETBE according to this embodiment.
The method for producing ETBE according to this embodiment includes a dehydration step S1 for removing water mixed in ethanol, a main reaction step S2 for reacting a hydrocarbon containing isobutene and ethanol in the presence of a reaction catalyst, and a mixture. Reactive distillation in a distillation column to obtain ETBE, the reactive distillation step S3, and the residue in the reactive distillation step S3 is reactively distilled under high-pressure conditions to obtain ETBE, and the ETBE distillation step S4 is unreacted from the residue An isobutene recovery step S5 for recovering the isobutene, and an ethanol recovery step S6 for recovering unreacted ethanol from the residue after the isobutene recovery step S5.

According to the manufacturing method of ETBE which concerns on this embodiment, by providing ETBE distillation process S4 performed on high pressure conditions, highly purified ETBE can be obtained with a sufficient yield with a simple method.
In addition, since both the reactive distillation step S3 and the ETBE distillation step S4 do not require a special apparatus, the apparatus can be enlarged and put into practical use.

Hereinafter, each step will be described in more detail.
(Dehydration process)
The dehydration step S1 is a step of removing water mixed in ethanol. By providing dehydration process S1, a side reaction is suppressed and the yield of ETBE improves. In addition, since ethanol is easily mixed with water and azeotropes with water, water is generally mixed therein. Of course, when using high purity ethanol, this step is not necessary.

Here, the ethanol used is not particularly limited, but is preferably obtained by hydrolyzing lignocellulose into sugar and fermenting the sugar. In this case, ETBE can be manufactured by a low environmental load type process.
For example, lignocellulose (woody biomass) containing lignin, cellulose and hemicellulose is ground, softened, etc., then contacted with an enzyme to saccharify, and ethanol is obtained by fermenting the resulting sugar.
In this case, it is preferable to use an ethanol aqueous solution having an ethanol concentration of 90% by weight or more.

In the dehydration step S1, dehydration is performed using a water adsorbent.
Here, as the water adsorbent, molecular sieve (synthetic or natural zeolite, carbon molecular sieve, etc.), silica gel, activated alumina, ion exchange resin, sulfate anhydride, carbonate anhydride, activated carbon, starch, etc. Can be mentioned. In addition, these may be used individually by 1 type, or may be used in mixture of multiple types.
Among these, it is preferable to use a molecular sieve as the water adsorbent. Specifically, commercially available granular molecular sieves such as naturally occurring zeolite, synthetic zeolite, and carbon molecular sieve are preferably used.

The shape of the granular molecular sieve is not limited to a spherical shape, a cylindrical shape, a pellet shape, a crushed shape, a granular shape, or the like.
The particle size of the granular molecular sieve is preferably in the range of 3 to 30 mesh, and more preferably the average pore diameter is 0.2 to 0.5 nm.

  Specifically, granular zeolite 3A, zeolite 4A, zeolite 5A, or NSC-4 carbon molecular sieve is preferably used. As the commercially available granular molecular sieve, molecular sieve 3A (manufactured by Wako Pure Chemical Industries, Ltd.), zeolite 4A is used. (Manufactured by Tosoh Corporation) is preferably used.

In the dehydration step S1, the dehydration temperature is preferably 20 to 200 ° C, more preferably 40 to 100 ° C.
Further, after dehydration, the water concentration in the raw ethanol is preferably 3000 ppm or less.

(Main reaction process)
The main reaction step S2 is a step in which a hydrocarbon containing isobutene and ethanol are reacted in the presence of a reaction catalyst. By performing this step, the reaction between isobutene and ethanol can be brought into an equilibrium state, and ETBE can be efficiently obtained by biasing the equilibrium state in the reactive distillation step S3 described later.

  In the main reaction step S2, as described above, when the hydrocarbon is supplied from an ethylene plant or a crude fluidized catalytic reformer or fluidized catalytic cracker, crude hydrogen gas includes isobutene, propane. , Isobutane, 1-butene, 2-butene and pentane. Even in this case, the ETBE can be selectively and efficiently manufactured in the ETBE manufacturing method according to the present embodiment. The isobutene concentration in the hydrocarbon is preferably 5% by weight or more, and more preferably 15% by weight or more.

The molar ratio of isobutene to ethanol as a raw material is preferably 0.1 to 10 mol, and more preferably 0.5 to 2 mol.
If the molar ratio is less than 0.1, the proportion of ethanol in the raw material cost is higher than in the case where the molar ratio is within the above range, so there is a disadvantage that the proportional cost increases, and the molar ratio is 10 When the ratio exceeds 1, there is a drawback that side reactions increase compared to the case where the molar ratio is within the above range.

In the main reaction step S2, the reaction catalyst is preferably a cation exchange resin. In this case, the reaction between isobutene and ethanol proceeds promptly.
As such a cation exchange resin, a strongly acidic cation exchange resin is preferably used. As such a strongly acidic cation exchange resin, a porous type (MR type) styrene resin into which a strong acid group such as a sulfonic acid group (—SO ₃ H) is introduced as an ion exchange group is preferable.
Examples of commercially available products include “Amberlist” (organo), “Diaion” (Mitsubishi Chemical), “Amberlyst”, “Amberlite” (USA: Rohm and Haas), “Dowex” (USA: Dow)・ Chemicals), “Duolite” (USA: Diamond Shamrock).

  The particle size of the strongly acidic cation exchange resin is preferably 0.5 to 1.0 mm.

The amount of the reaction catalyst used is preferably 1 to 90 g, more preferably 1 to 90 g, and still more preferably 4 to 9 g with respect to 1 mol of ethanol.
When the amount used is less than 1 g, the reaction may not be completed as compared with the case where the amount used is within the above range, and even if the amount used exceeds 90 g, the catalytic effect reaches its peak, resulting in high costs. Become.

In the main reaction step S2, the method of using the reaction catalyst is not particularly limited, and the reaction catalyst can be used in the state of a fixed bed, a fluidized bed, or a suspended bed.
In addition, the form of reacting isobutene and ethanol is not particularly limited, but it is preferably applied by a pressurized gas-liquid mixed phase reaction method in which ethanol can maintain a liquid phase. In this case, the yield of ETBE obtained is further improved.

In the pressurized gas-liquid mixed phase reaction system, it is preferable that isobutene circulates in the gas phase.
At this time, the weight ratio between the circulation flow rate of the gas phase portion (mainly hydrocarbon) and the new supply amount is preferably in the range of 0.5 to 10, and from the viewpoint of the power consumption cost of the circulation gas blower, 2 More preferably, it is in the range of ˜3.

In the pressurized gas-liquid mixed phase reaction system, the atmospheric pressure during the reaction is preferably set to be equal to or higher than the pressure at which ethanol can maintain the liquid phase.
At this time, the liquid phase portion (mainly ethanol and ETBE) is preferably partially circulated, and in some cases, the circulating flow is preferably cooled. At this time, the weight ratio between the circulation flow rate and the new supply amount is preferably in the range of 0.5 to 20, more practically in the range of 2 to 3.

In the pressurized gas-liquid mixed phase reaction method, the reaction temperature can be selected in a wide range depending on the pressure, the liquid space velocity, the catalyst amount, the target reaction rate, etc., but from the viewpoint of suppressing the deactivation of the reaction catalyst described later, 100 It is preferably not higher than ° C., more preferably 10 to 100 ° C., and further preferably 40 to 90 ° C. from the viewpoint of practicality.
When the reaction temperature is too low, a practical reaction rate cannot be obtained, and when the reaction temperature is too high, side reactions are liable to occur and the reaction catalyst is easily deactivated.

  In the pressurized gas-liquid mixed phase reaction method, the reaction pressure is preferably 0.3 MPa or more, and more preferably 0.4 to 1.0 MPa from the viewpoint of practicality. In this case, the liquid state of ethanol can be maintained.

In the pressurized gas-liquid mixed phase reaction method, the liquid space velocity is preferably 0.1 to 10 (m ³ -ethanol / hr / m ³ -catalyst), and 3 to 7 (m ³ -ethanol / hr / m ³ -catalyst).

  In the pressurized gas-liquid mixed phase reaction system, distillation can be performed in any of a flow system, a batch system, and a semi-batch system.

  The hydrocarbons, ethanol, and ETBE containing isobutene that have undergone the main reaction step S2 are supplied to the reactive distillation step S3 as a mixture.

(Reactive distillation process)
The reactive distillation step S3 is a step of obtaining ETBE by reactive distillation of the above mixture under high pressure conditions. In the reactive distillation step S3, isobutene and ethanol are reacted in the presence of a reaction catalyst, similarly to the main reaction step S2 described above.

First, in the reactive distillation step S3, isobutene and ethanol contained in the residue after the main reaction step S2 are reacted.
Such a reaction is performed by a reactive distillation method in which a low-temperature reaction heat having a relatively low reaction temperature can be effectively used.

  In the reactive distillation step S3, the temperature of the reactive distillation part (intermediate part) of the distillation column is preferably 100 ° C. or less from the viewpoint of suppressing the deactivation of the reaction catalyst. The temperature at the top of the distillation column is preferably 30 to 80 ° C, and more preferably 40 to 60 ° C from the viewpoint of practicality. The temperature at the bottom of the distillation column is preferably 90 to 150 ° C, and more preferably 100 to 130 ° C from the viewpoint of practicality.

  Further, the tower top pressure is preferably 0.7 MPa or less, and more preferably 0.5 MPa or less.

In the reactive distillation step S3, the reflux ratio of the distillation column is preferably operated at 0.1 to 4, more preferably 0.2 to 0.8.
The distillation separation stage of the distillation column has 5 to 20 theoretical plates required above the reaction catalyst, and preferably 7 to 10 theoretical plates from the viewpoint of practicality. The number of theoretical plates required below the reaction catalyst is 2 to 30 theoretical plates, and 3 to 10 theoretical plates are preferable from the viewpoint of practicality.
The supply to the distillation column has a required number of theoretical plates of 2 to 13 theoretical plates below the packing, and is preferably 3 to 10 theoretical plates from the viewpoint of practicality.

  Here, as the above-mentioned packing, regular packing such as Sulzer packing (product of Sulzer), Lombo packing (product of Kunii), Monz packing (product of Monz), etc. in which one theoretical plate is in the range of 0.2 to 1.0 m. Or irregular packing such as pole ring (Norton product), Raschig ring, cascade mini-ring (Dotwell product, registered trademark) whose one theoretical plate is in the range of 0.8 to 2.0 m. It is done.

Incorporation of the reaction catalyst (cation exchange resin) into the regular packing is preferably dense packing in view of catalytic activity to ethanol, but rough packing is preferable from the viewpoint of gas permeability.
The method of incorporating the cation exchange resin into the regular packing is not particularly limited, and may be directly incorporated, or may be wrapped and filled in a fiberglass cloth or Teflon (registered trademark) cloth that is inert to the reaction.
In this catalyst zone, a distillation action equivalent to 1 to 3 theoretical plates per 1 m of packing height is assumed.

  The amount of the cation exchange resin incorporated into the distillation column is such that a reaction rate of 50 to 95 mol% is achieved, preferably 70 to 85 mol%, with respect to the amount of ethanol supplied to the distillation column. An amount such that the rate is achieved.

  In the reactive distillation step S3, it is preferable that ETBE having a purity of 95% by weight or more is taken out under a pressure condition of 0.7 MPa or less. In this case, ETBE can be obtained efficiently.

(ETBE distillation process)
The ETBE distillation step S4 is a step of obtaining ETBE by reactive distillation of the residue in the reactive distillation step S3 under high pressure conditions.

  In the ETBE distillation step S4, the pressure at the top of the distillation column is preferably greater than 0.23 MPa, and more preferably 0.3 to 1.5 MPa.

  The temperature of the distillation tower is preferably 50 to 90 ° C. at the top and 130 to 180 ° C. at the bottom.

The number of required theoretical plates of the distillation column is preferably 10 to 30 theoretical plates, and more preferably 15 to 25 theoretical plates from the viewpoint of practicality.
The reflux ratio is preferably operated in the range of 0.1 to 5, and more preferably in the range of 2.0 to 3.0 from the viewpoint of practicality.

  In the ETBE distillation step S4, when ETBE having a purity of 95% by weight or more is taken out under a pressure condition of more than 0.23 MPa, ETBE can be obtained efficiently, and recovery loss of unreacted isobutene and ethanol can be reduced. it can.

(Isobutene recovery process)
The isobutene recovery step S5 is a step of recovering unreacted isobutene from the residue in the ETBE distillation step S4.

In the isobutene recovery step S5, the pressure at the top of the distillation column is preferably increased. Specifically, the pressure is preferably 0.5 to 1.5 MPa.
The required number of theoretical plates of the distillation column is preferably operated in the range of 2 to 15 theoretical plates, and more preferably in the range of 3 to 7 theoretical plates from the viewpoint of practicality.
A method in which the supply stage to the distillation column is at the bottom of the distillation column by using sensible heat of the feed material to reduce the heat load of the distillation column, or there is no new heat load at the distillation column, or the top of the column It is preferable to supply more water and not reflux.
As the packing to be packed in the distillation column, the above-mentioned regular packing or irregular packing can be used, but from the viewpoint of economy, it is preferable to use the irregular packing.

  In addition, the obtained isobutene can be reused as a raw material of the manufacturing method of ETBE.

(Ethanol recovery process)
The ethanol recovery step S6 is a step of recovering unreacted ethanol from the residue in the isobutene recovery step S5.

In the ethanol recovery step S6, water must be distilled and separated when recovering ethanol.
Here, it can be said that it is more advantageous to carry out distillation separation at normal pressure in view of problems such as gas-liquid equilibrium characteristics of ethanol and water and equipment costs. Further, when recovering ethanol, more theoretical distillation stages are required than the vapor-liquid equilibrium characteristics of ethanol and water shown in FIG.

For these reasons, in the ethanol recovery step S6, the pressure at the top of the distillation column is set to normal pressure.
The temperature of the distillation tower is preferably 65 to 90 ° C. at the top and 90 to 120 ° C. at the bottom.
The supply stage to the distillation column is preferably supplied to 8 to 12 theoretical stages from the top of the distillation stage where the temperature of the substance to be supplied is substantially equal to the temperature of the supply stage of the distillation tower.
The number of required theoretical plates of the distillation column is preferably 8 to 30 theoretical plates, and more preferably 10 to 20 theoretical plates from the viewpoint of practicality.
The reflux ratio is preferably operated in the range of 2 to 20, and more preferably in the range of 8 to 12 from the viewpoint of practicality.
The packing packed in the distillation column is preferably the above-described ordered packing.

  In the ethanol recovery step S6, it is preferable to distill ethanol having a purity of 96% by weight or less under normal pressure conditions, and then to perform a dehydration step for removing water mixed in the ethanol and reuse it.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, the ETBE production method according to the present embodiment includes the main reaction step S2 in which isobutene and ethanol are reacted in the presence of a reaction catalyst, but it is not always necessary.

The isobutene recovery step S5 and the ethanol recovery step S6 are not necessarily essential, and the order in which they pass is not particularly limited.
The recovered ethanol and isobutene may be directly passed to the main reaction step S2 or the reactive distillation step S3, or may be passed to the main reaction step S2 or the reactive distillation step S3 via the dehydration step S1 or the like. You may take out temporarily and use for manufacture of ETBE separately.

FIG. 5 is a flowchart showing a manufacturing method of ETBE in the embodiment.
Hereinafter, the present invention will be described more specifically based on the example shown in FIG. 5, but the present invention is not limited to the following example.

(Dehydration process)
Ethanol was supplied from the channel 100 and the channel 280 to the dehydration tower A100. In the dehydration tower A100, a tank type stainless steel reaction vessel with an internal volume of 500 ml was filled with 150 ml of molecular sieve 3A (water adsorbent, manufactured by Wako Pure Chemical Industries, Ltd.), and the reaction vessel space was sealed with nitrogen gas. Is.
In the dehydration tower A100, the dehydration step was performed at a temperature of 67 ° C. and a pressure of 0.101 MPa. The water separated by dehydration was discharged out of the system through the flow path 120.
The water content of the ethanol thus obtained was 2055 ppm as measured with a Karl Fischer moisture analyzer.

(Main reaction process)
The obtained ethanol is put into the pressurized gas-liquid mixed phase reaction vessel R100 through the flow path 130, the liquid pump P100 (pump efficiency 90% of the liquid pump) and the flow path 140, and the hydrocarbon (isobutene) as the raw material for the other reaction 17.5% by weight, propane 2.5% by weight, isobutane 26.0% by weight, 1-butene 44.8% by weight, butane 7.9% by weight and pentane 1.4% by weight). The pressure-gas / liquid mixed phase reaction vessel R100 was supplied (ethanol / isobutene molar ratio 1 / 1.1). The pressurized gas-liquid mixed phase reaction vessel R100 is composed of a tank type stainless steel reaction vessel with a stirrer having an internal volume of 100 ml and filled with 15 ml of a cation exchange resin (reaction catalyst, manufactured by Organo).

  Then, ethanol and isobutene were supplied from the top of the reaction vessel at a temperature of 70 ° C. and a pressure of 0.507 MPa, and the gas phase portion was circulated to produce ETBE. The ethanol reaction rate at this time was 45.3 mol%, and the ETBE yield was 99.3 mol%.

(Reactive distillation process)
Next, these mixtures were supplied to the reactive distillation column RD100 via the flow path 150.
A reactive distillation column RD100 is a reaction tube having an inner diameter of 15 mm and a length of 200 mm filled with 10 ml of a cation exchange resin (manufactured by Organo). It consists of 6 theoretical plates (filled with cation exchange resin) and a lower distillation separation stage 9 theoretical stages. The catalyst layer temperature was 60 ° C., the reaction pressure was 0.5 MPa, the ethanol / isobutene molar ratio was 1 / 1.1, and the liquid space velocity with respect to the catalyst capacity of the ethanol supply amount dehydrated by molecular sieve was 4.00 / h.

  In the reactive distillation column RD100, the mixture is fed from the top of the column to 15 theoretical plates, the pressure at the top of the column is 0.355 MPa, the temperature at the top of the column is 51 ° C., the temperature of the reactive distillation is 70 ° C., the bottom of the column is 118 ° C., and the reflux ratio is Reactive distillation was performed at 0.3. The ethanol reaction rate at this time was 80.6 mol%, and the ETBE yield was 99.3 mol%.

The gas phase portion (mainly unreacted hydrocarbon, ethanol corresponding to the vapor pressure and unseparated ETBE) flowing out from the top of the reactive distillation column RD100 is composed of a flow path 180, a compressor C100 (adiabatic efficiency of compressor 80%). ) To the ETBE distillation column D100, and the liquid phase part (mainly unreacted hydrocarbons, ethanol and unseparated ETBE for the dissolution equilibrium) are flow path 170, liquid pump P200 (the pump efficiency of the liquid pump is 90%) ), And supplied to the ETBE distillation column D100 via the flow path 190.
From the bottom of the reactive distillation column RD100, ETBE having a purity of 98.0% by weight was taken out through the flow channel 160 and the flow channel 230.

(ETBE distillation process)
The ETBE distillation column D100 is composed of 18 theoretical plates.
The gas phase part and the liquid phase part are supplied to 9 theoretical plates from the top of the ETBE distillation column D100, the top pressure is 1.013 MPa, the top temperature is 76 ° C., the bottom is 166 ° C., and the reflux ratio is 3 0.0.
The residue (mainly unreacted hydrocarbon, ethanol, unseparated ETBE) flowing out from the top of the ETBE distillation column D100 is cooled at 73 ° C. in the heat exchanger EX100 through the flow path 220, and unreacted through the flow path 240. The reaction was supplied to the isobutene distillation column D200.
Further, ETBE having a purity of 98.0% by weight was taken out from the bottom of the tower, and joined to the flow path 230 through the flow path 210 to obtain ETBE.

(Isobutene recovery process)
The unreacted isobutene distillation column D200 is composed of 5 theoretical plates, and supplies reflux water from the flow path 310 to the top of the column. The column top pressure is 1.013 MPa, the column top temperature is 66 ° C., and the column bottom is 30 ° C. Distillation separation was performed.
Components (mainly unreacted hydrocarbon, water corresponding to vapor pressure, ethanol, ETBE) flowing out from the top of the unreacted isobutene distillation column D200 were discharged out of the system through the flow path 260. The unreacted ethanol taken out from the bottom of the column was supplied to the unreacted ethanol distillation column D300 via the flow path 250.

(Ethanol recovery process)
The unreacted ethanol distillation column D300 is a distillation column having a width of 100 mm, a height of 1200 mm, and a depth of 60 mm filled with irregular packing so that the number of theoretical plates is equivalent to 20. The distillation conditions were such that the tower top temperature was 79 ° C. and the ethanol concentration supplied was 10 wt%. The unreacted ethanol was continuously supplied so as to be 5.0 kg / h from the height of the center of the tower. Furthermore, the reflux amount at the top of the column was 4.8 kg / h.

The unreacted ethanol distillation column D300 is composed of 23 theoretical plates.
In the unreacted ethanol distillation column D300, unreacted ethanol is supplied from the top to the 19th theoretical plate, the top pressure is 0.101 MPa, the top temperature is 75 ° C., the bottom temperature is 100 ° C., and the reflux ratio is 10.0. As a result, distillation separation was performed.
As a result, the recovered ethanol concentration was 90 wt% or more.

  The purity 94.4 wt% ethanol flowing out from the top of the unreacted ethanol distillation tower D300 was supplied to the dehydration tower A100 via the flow path 280 and reused. The water discharged from the bottom of the tower passes through the flow path 270 and merges with the flow path 290 for supplying water for replenishing water corresponding to the vapor pressure flowing out from the top of the unreacted isobutene distillation tower D200. The solution was cooled to 70 ° C. by the heat exchanger EX200 through the liquid pump P300 and the flow path 310, and supplied to the top of the unreacted isobutene distillation tower D200 through the flow path 320.

The calculation method of ETBE in this example was calculated (US: General-purpose process simulator PROII of Simuration Sciences, Inc. was used, and the calculation formula was SRKM (Soave-Redlich-Kwong Modified) using pentane / water, ETBE / Vapor-liquid equilibrium data were incorporated for the ethanol system.)
In addition, the temperature in each flow path, a pressure, and each component composition are shown to Tables 2-4. In the table below, “L” in the column of each component composition indicates liquid, “V” indicates gas, and “M” indicates a gas-liquid mixed state.

[Table 2]

[Table 3]

[Table 4]

  In the method for producing ETBE according to this example, 119.14 tons of ETBE having a purity of 98% by weight could be obtained from 57.41 tons of ethanol and 76.84 tons of isobutene in low-purity isobutene. The component composition of ETBE is ETBE 98.01% by weight, isobutane 0.02% by weight, 1 butene 0.06% by weight, butane 0.02% by weight, diethyl ether 0.01% by weight, pentane 0.17% by weight. 0.69% by weight of ethanol, 0.30% by weight of tertiary butanol, 0.21% by weight of ethyl 2-butyl ether, 0.52% by weight of isobutylene (isobutane, a gaseous substance at room temperature, 1 butene and butane are dissolved equilibrium components) )Met.

Based on the above, the ETBE recovery rate was 96.0%, and the unreacted ethanol recovery rate was 97.4% (ethanol purity of the ethanol aqueous solution 94.4% by weight). Note that unrecovered ETBE and ethanol are discharged out of the system together with unreacted low-purity isobutene as a portion corresponding to the vapor pressure.
Therefore, in this system, it was confirmed that ETBE can be manufactured and refined, and unreacted ethanol can be reused, and at the same time, the reaction heat can be effectively used to produce ETBE with high heat utilization in terms of equipment cost and operating cost. .

100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 280, 290, 300, 310, 320... ..Dehydration tower C100 ... Compressor D100 ... ETBE distillation tower D200 ... Unreacted isobutene distillation tower D300 ... Unreacted ethanol distillation tower P100, P200, P300 ... Liquid pump R100 ... Addition Pressure-liquid mixed phase reaction vessel RD100 ... Reactive distillation column S1 ... Dehydration step S2 ... Main reaction step S3 ... Reactive distillation step S4 ... ETBE distillation step S5 ... Isobutene recovery step S6 ... Ethanol recovery process

Claims (14)

A dehydration step of mixing water in ethanol with a water adsorbent to reduce the water concentration in ethanol to 3000 ppm or less;
A main reaction step in which a hydrocarbon containing isobutene and ethanol are reacted in the presence of a reaction catalyst ;
Reactive distillation of the mixture in a distillation column to obtain ETBE; and
An ETBE distillation step in which the residue in the reactive distillation step is reactively distilled under high-pressure conditions to obtain ETBE;
Equipped with a,
The ethanol is obtained by hydrolyzing lignocellulose into a saccharide and fermenting the saccharide.
The main reaction step is performed by a pressurized gas-liquid mixed phase reaction method,
Method for producing ETBE said reactive distillation step Ru decorated with reactive distillation method.   The method for producing ETBE according to claim 1, wherein a high-pressure condition in the ETBE distillation step is 0.23 MPa or more.   The method for producing ETBE according to claim 1, wherein the hydrocarbon further contains at least one selected from the group consisting of propane, isobutane, 1-butene, 2-butene and pentane. In the dehydration step, ETBE method according to any one of claims 1 to 3 you a dehydration temperature and 20 to 200 ° C.. The catalyst is, Ri strongly acidic cation exchange resin der made of a porous type styrene resin strong acid group is introduced as an ion-exchange group,
The particle size of the strongly acidic cation exchange resin is 0.5 to 1.0 mm,
Wherein the amount of reaction catalyst, with respect to ethanol 1 mole, ETBE method according to claim 1 shall be the 1～90G. The isobutene concentration in the hydrocarbon is 5 wt% or more,
Method for producing ETBE according a molar ratio of the isobutene to said ethanol feedstock to any one of claims 1 to 5 shall be the 0.1 to 10 mol.   The method for producing ETBE according to any one of claims 1 to 6, wherein in the reactive distillation step, ETBE having a purity of 95% by weight or more is discharged under a temperature condition of 100 ° C or lower. In the pressurized gas-liquid mixed phase reaction process, the reaction temperature was 100 ° C. or less, the pressure during the reaction and the ethanol than the pressure that can hold a liquid phase, according to claim 1 wherein the isobutene that are adapted to circulate a vapor-phase The manufacturing method of ETBE as described in any one of -7. In the pressurized gas-liquid mixed phase reaction method, the reaction pressure was more than 0.3 MPa, a liquid space velocity from 0.1 to 10 either with to that claim. 1 to 8 (m ³ - catalyst - ethanol / hr / m ³⁾ A method for producing ETBE according to claim 1 . In the reactive distillation step, the temperature of the reactive distillation section of the distillation tower is 100 ° C. or less, the temperature of the top of the distillation tower is 30 to 80 ° C., the temperature of the bottom of the distillation tower is 90 to 150 ° C., and the top of the tower and the pressure of the 0.7MPa or less, ETBE method according to any one of claims 1-9 operated so that a reflux ratio of the distillation column becomes 0.1 to 4. In the ETBE distillation step, the temperature at the top of the distillation column is 50 to 90 ° C., the temperature at the bottom of the distillation column is 130 to 180 ° C., the pressure at the top of the distillation column is greater than 0.23 MPa, ETBE method according to any one of claims 1 to 10 Ru was out cans 95% or more by weight of ETBE. An isobutene recovery step of recovering unreacted isobutene from the residue in the ETBE distillation step;
An ethanol recovery step of recovering unreacted ethanol from the residue after the isobutene recovery step;
Further ETBE method according to any one of claims 1 to 11, Ru comprising a. Wherein the isobutene recovery step claim 12 ETBE method according to the pressure of column top shall be the 0.5~1.5MPa distillation column. In the ethanol recovery step, the pressure at the top of the distillation column is normal pressure, the temperature at the top of the distillation column is 65 to 90 ° C, the temperature at the bottom of the distillation column is 90 to 120 ° C,
After purity was distilled ethanol 96 wt% or less, subjected to a dehydration step of removing water are mixed in the ethanol, ETBE method according to claim 12 or 13 you reuse.

Images