JP2005162669A - Method of synthesizing etbe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method of synthesizing ethyl t-butyl ether (ETBE) which does not use a reaction distillation column. <P>SOLUTION: Isobutene (IB) as the major component, a C4 fraction liquefied under pressure at normal temperatures, and water containing ethanol (EtOH) obtained by fractionating bioethanol are used as raw materials, and IB is stoichiometrically reacted with EtOH and water in the liquid phase under mild conditions of a medium pressure (≤1,000 kPa) and a medium temperature (≤100°C) with the use of a reactor (a reaction column) 14 having a fixed catalyst reaction stage 22 to synthesize t-butyl alcohol (TBA) together with ETBE. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ETBE synthesis method and an ETBE synthesis apparatus suitable for the production.

Here, the ETBE, "e thyl t ert- b utyl e ther ( ethyl Tasharyi-butyl ether)" is an abbreviation of, MTBE has attracted attention as a high-octane fuel base stock (m ethyl t ert- b utyl e ther) is attracting attention as a high-octane fuel base material (octane number: 112).

  With the enactment of the new air purification law in the United States and the growing awareness of global environmental issues, the emergence of alternative fuels for gasoline is demanded.

  As a gasoline alternative fuel, MTEB that can be produced by directly reacting isobutene (IB) and methanol (MeOH) has attracted attention and is produced in large quantities all over the world (SUMMERY OF THE JP And the first stage of each of Non-Patent Documents 1 to 3).

  However, recently, MeOH as a raw material is toxic and has a high vapor pressure, so that it easily evaporates. For this reason, it has been attempted to use EtOH, which is a biomass (biological energy) that has no toxicity and can be used instead of MeOH (see each abstract of Non-Patent Documents 1 to 3).

  For example, t-butyl alcohol (TBA), which is a by-product of the production of propylene oxide, and EtOH are reacted in a reactive distillation column packed with a strongly acidic ion exchange resin as a catalyst, as in MTBE (the following reaction formula) reference).

TBA + EtOH → ETBE + H ₂ O
At the same time, since IB is generated by the decomposition reaction of TBA (TBA → IB + H ₂ O), ETBE can be produced by the following reaction using IB rich gas.

IB + EtOH → ETBE
Furthermore, Patent Document 1 describes a technique for producing ETBE by reacting a C4 fraction containing IB with EtOH using a reactive distillation column equipped with a fixed bed reactor filled with an ion exchange resin. (See abstract claims, etc.).

Each technique uses a reactive distillation column, and the C4 fraction is supplied to the reactive distillation column in a gas state.
US Pat. No. 5,248,836 “JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol.32, No3” (1999) p280-287, edited by The Society of Chemical Engineers, Japan “JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol.32, No4” edited by The Society of Chemical Engineers, Japan (1999) p539-543 MAAbraham and RPHeketh edited by “Reaction Engineering for Pollution Prevention” (2000), published by Elesvier Science BV, p237-246

  In view of the above, an object of the present invention is to provide a novel ETBE synthesis method and synthesis apparatus that do not use the above reactive distillation column.

  The present inventor has come up with a method for synthesizing ETBE having the following configuration in the course of diligent research and development in order to solve the above problems.

A method of synthesizing ETBE,
C4 fraction (hereinafter referred to as “C4 fraction”) and hydrated EtOH consisting of IB or liquefied under pressure of IB as a main component,
Using a reactor equipped with a reaction stage of a fixed catalyst, IB is subjected to a liquid phase reaction with EtOH and water under a stoichiometric pressure to synthesize TBA together with ETEB.

  The C4 fraction is usually contained in a BB fraction produced by naphtha cracking (cracking) in an oil plant, and is essentially a gas. For this reason, there has been no idea for those skilled in the art to bother to liquefy and use as a reaction raw material. In addition, the raw material EtOH can be hydrated, and it is not necessary to dehydrate it or use highly rectified one.

  And the said liquid phase reaction can be performed on moderate conditions of medium temperature and medium pressure (100 degrees C or less, 1000 kPa or less).

  Also, TBA synthesized (by-product) with ETBE has a considerably high octane number (octane number: 100). For this reason, even if it does not carry out TBA separation operation, it can be used as a high-octane fuel base material (particularly, fuel for race cars) as a TBA mixture of ETBE.

  In the above configuration, the C4 fraction and the water-containing EtOH are introduced into the raw material supply stage located on one side of the fixed catalyst reaction stage, and the product ETBE from the product discharge stage located on the other side is used as a TBA mixture at room temperature and normal temperature. It is desirable to recover the pressure (atmospheric pressure). By recovering the ETBE TBA mixture at atmospheric pressure, the unreacted C4 gas component can be separated and recovered from the ETBE component. Further, as described above, the ETBE TBA mixture can be used as it is as a high-octane fuel base without undergoing a TBA separation operation.

  In the above method, as the fixed catalyst reaction stage, acidic ion exchange resin layers may be arranged in multiple stages with a predetermined gap. By arranging the catalyst layers in multiple stages at intervals, the contact efficiency of the catalyst with the reaction liquid increases.

  In the above configuration, the acidic ion exchange resin layer may be filled with an inorganic fiber layer having cushioning properties. The degree of compression of the exchange resin layer under pressure is reduced, and the catalyst contact efficiency and the raw material flow in the reaction stage are improved.

  Desirably, the water-containing EtOH is bio-EtOH having a water content of about 5 to 30 vol%. The water content of about 5% is the water content of the azeotropic mixture of EtOH and water, and it is not necessary to azeotrope with benzene or the like to dehydrate further. On the other hand, if the water content exceeds 30 vol%, the mixing ratio of TBA increases, which may make it unsuitable as a high-octane fuel base material.

  Usually, the operating conditions in the reaction stage of the fixed catalyst reactor (reaction tower) are usually about 60 to 100 ° C. × about 700 to 1000 kPaabs (desirably about 70 to 80 ° C. × about 800 to 900 kPa (abs)). . If the temperature is too low or the pressure is too low, it is difficult for the synthesis reaction to proceed at a rate that allows industrialization.

  As an ETBE synthesizing apparatus used in the above-described ETBE synthesizing method, for example, the following configuration can be used.

A pressure-type catalytic reactor equipped with temperature control means, a pressurized raw material tank for C4 fraction, a normal pressure raw material tank for hydrous EtOH, and a product recovery tank for ETBE,
The catalytic reactor comprises a raw material supply stage on one of the upper and lower sides of the fixed catalyst reaction stage, and a product discharge stage on the other,
At the raw material supply stage, an atmospheric pressure raw material tank for EtOH and a pressurized raw material tank for C4 fraction are connected via a water-containing EtOH / C4 fraction supply pipe equipped with a fixed amount supply pump, respectively.
A product tank is connected to a product discharge stage of the pressurization type reactor via a product recovery pipe provided with a pressure regulating valve.

  In the apparatus having the above-mentioned configuration, the product recovery tank is a normal pressure type and includes a C4 gas recovery pipe, and the C4 gas discharge pipe is connected to the pressurized raw material tank and / or the IB fraction supply pipe so as to be appropriately circulated. It can be. It becomes easy to reuse or circulate C4 gas (unreacted C4 component) from ETBE.

  Further, in the above apparatus, a component detection means such as gas chromatography is provided in front of each quantitative supply pump of the water-containing EtOH / C4 fraction component supply pipe, and a component signal from the component detection means is sent to each quantitative supply pump. The stoichiometric reaction control means that is input and allows IB to be stoichiometrically reacted with EtOH and water can be used. Even if there is a change in the IB content of the C4 fraction or the EtOH content of the water-containing EtOH, a stoichiometric reaction is possible.

  Further, the catalyst reaction device includes a catalyst loading / exchanger that can be inserted and removed in the axial direction with respect to the reaction cylinder in order to fill and exchange the catalyst, and the catalyst loading / exchanger has one plate-like porous member or It is desirable to have a configuration in which a catalyst filling portion is provided that is connected to a plurality of connecting members at a predetermined pitch and includes a cushion layer on at least one of the opposing surfaces of the plate-like porous member. Catalyst loading / exchange is facilitated.

  Further, the catalytic reaction apparatus may be a multi-column type in which a plurality of reaction towers are arranged in a temperature control bath. In the case of the multi-tower system of this configuration, it is easy to scale up the ETBE synthesis apparatus.

  Hereinafter, embodiments of the present invention will be described in detail. In this specification, “%” or the like representing the blending amount is based on mass unless otherwise specified. Moreover, Pa which shows a pressure means an absolute pressure (abs) unless there is particular notice.

  First, an embodiment of an ETBE synthesizing apparatus used in the ETBE synthesizing method of the present invention will be described (see FIG. 1).

  Basically, a pressure-type catalytic reactor (reaction tower) 1414 equipped with a temperature control means (temperature control function) 12, a pressurized raw material tank 16 for C4 fraction, an atmospheric pressure raw material tank 18 for hydrous EtOH, And a product recovery tank 20 for ETBE.

  The catalyst reaction apparatus 14 includes a raw material supply stage (preheating stage) 24 on one side (lower side) of a fixed catalyst reaction stage (hereinafter simply referred to as “reaction stage”) 22 and a product discharge stage 26 on the other side (upper side). Each is equipped.

  The raw material supply stage 24 includes an atmospheric pressure raw material tank 18 for EtOH and a pressurized raw material tank 16 for the C4 fraction, each of which includes a water-containing EtOH and a check valve 31 and a check valve (check valve) 31. C4 fraction supply pipes 32 and 34 are connected.

  A product recovery tank (product recovery tank) 20 is connected to a product discharge stage 26 of the pressurization type reactor via a product recovery pipe 36 having a pressure regulating valve 28. Usually, in order to promote liquefaction of products (ETBE and TBA), a cooler (heat exchanger) 27 is disposed in front of the pressure regulating valve 28 in the product recovery pipe 36.

  Further, the gas discharge pipe 62 of the product recovery tank 20 is branched and connected to a C4 fraction return pipe 66 to the pressurized raw material tank 16 provided with a pressure pump 64.

  In the above, the catalyst reaction apparatus (reaction cylinder) 14 is a vertical type (vertical), which is a system in which raw material is supplied from the lower side and the product is discharged from the upper side, but the raw material is supplied from the upper side and the product is discharged from the lower side. It is also possible to use a horizontal type or a diagonal type. The effect of swelling the ion exchange resin can be reduced by supplying the raw material from the lower side and discharging the product from the upper side. Because the liquid flow is upward, the ion exchange resin is difficult to be consolidated (high density by compression).

  The temperature control means 12 is a jacket type in the illustrated example. That is, a temperature control jacket 38 is provided on the outer wall of the tower corresponding to the reaction stage 22 and the raw material supply stage 24 of the catalyst reaction apparatus (catalyst reaction tower) 14, and water from the temperature control water tank 42 is supplied to the temperature control jacket 38. Circulation is performed by a circulation pipe 46 provided with a circulation pump 44. The temperature control means 12 is not limited to the jacket system, but may be any of a resistance heating system, an induction heating system, and the above heating system. However, the ETBE synthesis reaction is inherently an exothermic reaction and can be cooled with water. The method is desirable because it facilitates temperature control.

  Further, in the above apparatus, a component detection means 48 such as gas chromatography is provided in front of each quantitative supply pump 30 of the water-containing EtOH / C4 fraction supply pipe, and a component signal from the component detection means (gas chromatography 48) 48 is provided. Can be configured to include a stoichiometric reaction control means that is input to each metering supply pump 30 and is capable of performing stoichiometric reaction of EtOH and IB. Even if there is a change in the EtOH content of the hydrous EtOH and the IB content of the C4 fraction, a stoichiometric reaction is possible. In the figure, reference numeral 50 denotes an arithmetic control unit (arithmetic controller).

  As a component detection means, other means may be developed in the future, but at present, gas chromatography is preferable because mass spectrometry can be easily performed.

  Next, a method for synthesizing ETBE using the ETBE manufacturing apparatus will be described.

  First, as shown in FIG. 2A, a catalyst layer (acidic ion exchange resin layer) 52 and a cushion layer (gap layer) 54 are alternately stacked and filled in the reaction stage 22 of the catalyst reaction device 14. Here, the thickness of the catalyst layer 52 and the cushion layer 54 varies depending on the required processing capacity (production capacity), but when the reaction tower inner diameter is 40 to 80 mm, the catalyst layer is 10 to 20 mm, and the cushion layer (or the gap layer). ): 5 to 10 mm.

Here, as the acidic ion exchange resin forming the strongly acidic catalyst layer, a strong acidic ion exchange resin for a catalyst is usually used. Specifically, as the strongly acidic ion 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 can be suitably used. is there. More specifically, it is a trade name (registered trademark) of “Amberlyst 15DRY / 15JWET / 35WET” as a catalyst / non-aqueous cation exchange resin from Roam and Haas. Products manufactured and sold can be used. In addition, the particle size of these strongly acidic ion exchange resins is usually 0.5 to 1.0 mm.

  The cushion layer 54 is formed to be porous with inorganic fibers (for example, rock wool, glass wool).

  In the above embodiment, the catalyst reaction device (reaction tower) 14 has a catalyst loading / removal capacity that can be taken in and out in the axial direction with respect to the main body of the reaction tower 14 in order to fill and exchange the catalyst as shown in FIG. It is desirable to have an exchanger 56.

  In the catalyst loading / exchanger 56, a plate-like porous member 58 is connected to one or a plurality of connecting rods 60 (one in the center in the figure) at a predetermined pitch. At least one (the lower side excluding the lowermost stage in the example) is provided with a catalyst filling portion 52 provided with a cushion layer 54. Here, the plate-like porous member 56 is a punching plate or a plastic molded body having a size (usually less than 1 mm) that does not allow catalyst particles to pass through. If the plastic molded body is formed of a material having cushioning properties, the cushion layer becomes unnecessary.

  The catalyst loading / exchanger 56 is easily inserted into the reaction tower 14 from the lower side, and is loaded with the catalyst from the upper side (70 to 80%) and then lowered. 52 can be filled with a catalyst. In addition, when the catalyst performance is reduced and it is time to replace, the catalyst swells and does not fall off unless force is applied from each catalyst filling portion. If it is completely extracted from the column 14 and a force is applied, it can be easily taken out (peeled off) from the catalyst packed portion 52.

  Instead of the catalyst loading / exchanger 56, a plurality of catalyst cartridges may be held on the connecting rod and loaded into the reaction column or taken out from the reaction column.

  Next, the pressurized raw material tank 16 is filled with a C4 fraction (usually C4 raffine), and the normal pressure raw material tank 18 is filled with water (EtOH / water azeotrope: EtOH 94 to 95%). Then, the temperature of the reaction stage 22 of the reaction apparatus is adjusted to about 100 ° C. or less, preferably 70 to 80 ° C. under a pressure of 1000 kPa (desirably 800 to 900 kPa) by the temperature adjusting means 12.

  Subsequently, the quantitative pump 30 is operated while quantitatively analyzing the IB content and the EtOH content in the C4 fraction and the water-containing EtOH by the gas chromatograph 48. At this time, since the temperature in the reaction tower 14 is raised to 70 to 80 ° C., the C4 fraction tends to vaporize. However, since the pressure in the reaction tower 14 is increased to about 700 to 1000 kPa by the pressure regulating valve 28 disposed on the product discharge port side of the product discharge stage 26, the C4 fraction is not vaporized.

  Therefore, IB and EtOH are activated by a strongly acidic catalyst (strongly acidic ion exchange resin), and a stoichiometric reaction (equivalent: 1 mol / 1 mol) as shown in the following reaction formula proceeds in a liquid phase.

(CH ₃ ) ₂ C═CH ₂ + C ₂ H ₅ OH → (CH ₃ ) ₃ COC ₂ H ₅ (ETBE)
In addition, since water exists, a side reaction is also accompanied.

(CH ₃ ) ₂ C═CH ₂ + H ₂ 0 → (CH ₃ ) ₃ COH (TBA)
In the C4 fraction (C4 raffine), butenes having a C double bond other than IB (1-butene, 2-butene (cis-trans isomer)) exist, but EtOH and water are Reacts preferentially with IB, where the heavy bond is susceptible to cleavage For this reason, butenes other than IB remain together with butanes as unreacted components.

  Each of the above reactions is a reversible reaction, but since it is a low temperature reaction, the equilibrium is shifted to the right and the conversion is high.

  The ETBE and TBA generated through the reaction stage 22 flows into the product recovery tank (product tank) 20 through the product recovery pipe 36 together with the unreacted C4 component. At this time, since the products other than ETBE (BP: 72 ° C), TBA (BP: 83.5 ° C) and unreacted EtOH (BP: 78.6 ° C) and water (BP: 100 ° C) are all normal temperature gases, It is recovered by a C4 gas component recovery tank (not shown) by the C4 gas component recovery pipe and used for other purposes. Other applications include polybutene and raw materials for synthesizing butadiene by dehydrogenation. At this time, the gasified C4 fraction may be appropriately returned to the pressurized raw material tank 16 via the C4 fraction return pipe 66 to reuse the unreacted IB.

  In addition, although the said catalyst reaction apparatus was made into the single tower type, as shown in FIG. 3, the reaction tower 14A, 14A ... of the reaction tower 14A, 14A ...... in the temperature control bathtub 68 was arrange | positioned. It may be a double tower type. In this case, it is easy to change the scale corresponding to the supply amount of the C4 fraction of the reaction. The temperature control bathtub 68 is kept warm by the heat insulating material 69 including the bath top surface, and the temperature control water can be temperature controlled via the heat exchanger 70.

  Next, a simulation result of an experimental reaction tube performed for producing ETBE will be described. The simulation program used was “EQUATRAN-G” of OMEGA SIMULATION.

  As the catalyst, “Amberlyst 15DRY” (strongly acidic ion exchange resin) having a specification that requires 10 kg when IB is supplied at 1 mol / s is used. When 200 g of this catalyst (apparent density 600 g / L) is used, the respective flow rates of IB and EtOH are as follows.

Here, IB molecular weight: 56 g, density (liquid): 0.6 g / cm ³ , azeotropic EtOH molar concentration: 0.963 mol%, EtOH molecular weight: 46 g, density (liquid): 0.81 g / cm ³ And equimolar reaction.

The IB flow rate (supply amount) is
56 g / mol × 0.2 kg / (10 kg · s / mol) ÷ 0.6 g / cm ³
= 1.87 cm ³ /s=6.73 L / h.

Also, the azeotropic EtOH flow rate (supply amount) is
46 g / mol × 0.2 kg / 0.963 (10 kg · s / mol) ÷ 0.81 g / cm ³
= 1.18 cm ³ / s = 4.25 L / h.

And when this dry ion exchange resin is packed in the reaction tower, it is set to about 70% packing assuming swelling during the reaction operation. Therefore, the capacity of the reaction tower is 200 g / (0.6 g / cm ³ ) ÷ 0.7 = 476 cm ³
Therefore, when forming a 500 cm ³ reaction stage 22 (resin filling part) in a reaction tower having an inner diameter of 3 cm, a reaction tube having a filling length of 70 cm and both end space parts of 15 cm is used.

    When IB and azeotropic EtOH having the above flow rates are supplied from the lower side of the reaction tube under the conditions of temperature: 70 ° C. and internal pressure: 980 kPa, a product having the following composition (mass%) can be obtained.

    ETBE: 84.7%, EtOH: 8.7%, TBA: 6.5%, water: 0.2%

It is a flowchart which shows one Embodiment in the synthesis | combining method of ETBE of this invention. (A) is a detailed structural diagram of the reaction column in FIG. 1, and (B) is a detailed structural diagram showing an example of a catalyst loading / exchanger for performing catalyst loading / exchange for the reaction column. (A) is a top view which shows an example of the multi-tubular catalyst reaction apparatus to which this invention is applied, (B) is a BB sectional drawing of this top view.

Explanation of symbols

12 ... Temperature control means (temperature control function)
14 ... Catalytic reactor (reaction tower)
16 ... Pressurized raw material tank (for C4 fraction)
18 ... Normal pressure raw material tank (for EtOH)
20 ... Product recovery tank 22 ... Fixed catalyst reaction stage 24 ... Raw material supply stage (preheating stage)
26 ... Product discharge stage

Claims (11)

A method for synthesizing ethyl-t-butyl ether (hereinafter abbreviated as “ETBE”),
C4 fraction (hereinafter referred to as “C4 fraction”) and hydrous ethanol (EtOH), which are composed of isobutene (IB) or mainly composed of IB and liquefied under pressure at room temperature, are used as raw materials.
Using a reactor equipped with a reaction stage of a fixed catalyst, the IB is subjected to a liquid phase reaction with EtOH and water under stoichiometric pressure to synthesize t-butyl alcohol (TBA) together with ETEB. A method for synthesizing ETBE.   The C4 fraction and the water-containing EtOH are charged into the raw material supply stage located on one side of the fixed catalyst reaction stage, and the product ETBE is recovered at room temperature and normal pressure from the product discharge stage located on the other side. The method of synthesizing ETBE according to claim 1.   The method for synthesizing ETBE according to claim 1 or 2, wherein the reaction stage is a multistage arrangement of acidic ion exchange resin layers with a predetermined gap.   The method for synthesizing ETBE according to any one of claims 1 to 3, wherein the acidic ion exchange resin layer is filled with an inorganic fiber layer having cushioning properties.   The method for synthesizing ETBE according to any one of claims 1 to 4, wherein the water-containing EtOH is bio-EtOH having a water content of about 5 to 30 vol%.   The method for synthesizing ETBE according to any one of claims 1 to 5, wherein the atmosphere of the raw material supply stage and the reaction stage of the catalytic reaction apparatus is 50 to 100 ° C x 700 to 1000 kPa (abs). A pressure-type catalytic reactor equipped with temperature control means, a pressurized raw material tank for C4 fraction, an atmospheric pressure raw material tank for hydrous ETOH, and a product recovery tank for liquid products,
The catalyst reaction apparatus includes a raw material supply stage on one of the upper and lower sides of the fixed catalyst reaction stage, and a product discharge stage on the other,
The raw material supply stage is connected to the normal pressure raw material tank for the water-containing ETOH and the pressurized raw material tank for the C4 fraction via a water-containing EtOH / IB component supply pipe each provided with a quantitative supply pump,
An ETBE synthesis apparatus, wherein a product tank is connected to a product discharge stage of the catalytic reactor via a product recovery pipe having a pressure regulating valve.   The product recovery tank is a normal pressure type and includes a C4 gas component discharge pipe, and the C4 gas discharge pipe is connected to the pressurized raw material tank and / or the IB fraction supply pipe so as to be appropriately circulated. The ETBE synthesis apparatus according to claim 7.   In front of each quantitative supply pump of the water-containing EtOH / IB fraction supply pipe, component detection means such as gas chromatography is provided, and a component signal from the component detection means is input to each quantitative supply pump, and IB 9. The ETBE synthesis apparatus according to claim 7 or 8, further comprising a stoichiometric reaction control means capable of performing a stoichiometric reaction with EtOH and water.   The catalyst reaction apparatus includes a catalyst loading / exchanger that can be inserted into and removed from the reaction cylinder in the axial direction in order to fill and exchange the catalyst, and the catalyst loading / exchanger includes a single plate-like porous member. Or it is the structure equipped with the catalyst filling part which was connected with the multiple connecting rod by predetermined pitch, and was provided with the cushion layer in at least one of the opposing surface of the said plate-shaped porous member. 9. The ETBE synthesis apparatus according to any one of 9 above. The ETBE synthesis apparatus according to any one of claims 7 to 10, wherein the catalytic reaction apparatus is a multi-column type in which a plurality of reaction towers are arranged in a temperature-controlled bath.