JP2013121946A - Method and apparatus for producing methacrolein and methacrylic acid from isobutanol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for producing a raw material of methacrylic resin efficiently from isobutanol.SOLUTION: This invention relates to: a method and apparatus for producing methacrolein and methacrylic acid from isobutanol, characterized by dehydrating and oxidizing the isobutanol by passing at least the isobutanol through a fixed-bed reaction device filled with a dehydration catalyst and an oxidation catalyst at a previous step and at a subsequent step, respectively; and an apparatus for producing the methacrolein and methacrylic acid, including the fixed-bed reaction device that is filled with the dehydration catalyst and the oxidation catalyst at the previous step and at the subsequent step, respectively, and dehydrates and oxidizes the isobutanol.

Description

  The present invention relates to a method for producing methacrolein and methacrylic acid from isobutanol, particularly biomass-derived isobutanol, and a production apparatus therefor.

Most conventional plastics are made from petroleum. However, in recent years, there is a concern about the depletion of oil, and CO ₂ generated when burnt causes global warming. In recent years, therefore, a biomass-derived chemical called carbon neutral has been expected as an alternative to petroleum.

  On the other hand, a methacrylic resin which is a kind of plastic is excellent in properties such as transparency and weather resistance, and is used in various applications. One method for producing methacrolein or methacrylic acid, which is a raw material of methyl methacrylate, which is a raw material of this methacrylic resin, is a catalytic gas phase oxidation method using t-butanol or isobutylene as a raw material.

  And various methods are conventionally known as a method for manufacturing the raw material used for a methacryl resin. For example, Patent Document 1 and Patent Document 2 describe a method for producing t-butanol (tertiary butanol) from butenes. Patent Document 3 describes a method for producing methacrolein from t-butanol. Patent Document 4 describes a method for producing methacrolein and methacrylic acid from isobutylene. Non-Patent Document 1 describes a method of synthesizing isobutylene from isobutanol. Furthermore, Patent Document 5 describes a method for producing methacrolein and methacrylic acid from isobutanol.

International Publication No. 99/33775 JP 2000-44502 A JP-A 48-32814 Japanese Patent Laid-Open No. 50-13308 JP 61-30538 A

Topics in Catalysis (2010) 53, 1224-1230

  However, all of the conventional methods for producing the methacrylic resin raw materials described in Patent Documents 1 to 4 described above are methods assuming a chemical derived from petroleum as a starting material. In other words, no consideration is given to the specific problems when using a biomass-derived chemical as a starting material.

  Although t-butanol is not directly produced by the current fermentation method, isobutanol can also be obtained by the fermentation method. However, in order to produce a methacrylic resin raw material from isobutanol, in the method of Non-Patent Document 1, isobutanol is separately produced. It is necessary to provide a dehydration step. Further, when the method described in Patent Document 5 is used, it is not necessary to provide a dehydration step of isobutanol, but the selectivity for the target product is very low. Therefore, in order to efficiently produce a methacrylic resin raw material using a biomass-derived chemical as a starting material, it is difficult to apply the conventional technology as it is.

  The present invention has been made to solve such problems. That is, an object of the present invention is to provide a method and apparatus capable of efficiently producing methacrolein and methacrylic acid from isobutanol.

  The present invention provides a process for producing methacrolein and methacrylic acid from isobutanol, wherein at least isobutanol is passed through a fixed bed reactor filled with a dehydration catalyst in the front stage and an oxidation catalyst in the back stage. A method for producing methacrylic acid.

  Furthermore, the present invention is an apparatus for producing methacrolein and methacrylic acid, comprising a fixed bed reactor for dehydrating and oxidizing isobutanol filled with a dehydration catalyst in the front stage and an oxidation catalyst in the back stage.

  ADVANTAGE OF THE INVENTION According to this invention, the method and apparatus which can manufacture methacrolein and methacrylic acid efficiently from isobutanol can be provided. The present invention can also be used as it is without modifying the conventional plant equipment to produce a methacrylic resin raw material, which is advantageous in terms of equipment cost. Furthermore, the present invention is particularly useful from the standpoint of environmental protection, since it is possible to carry out the reaction efficiently using isobutanol derived from biomass as a starting material.

  In the present invention, methacrolein and methacrylic acid are produced by dehydrating and oxidizing isobutanol. This reaction is carried out by passing at least isobutanol through a fixed bed reactor filled with a dehydration catalyst in the front stage and an oxidation catalyst in the rear stage.

  The isobutanol used as a starting material is not particularly limited. However, in the present invention, it is particularly preferable to use biomass-derived isobutanol from the viewpoint of environmental protection. The biomass-derived isobutanol is purified from an organic compound obtained through a fermentation process using fermentable sugar of plant biomass such as corn. Such biomass-derived isobutanol can also be obtained as a commercial product.

  When isobutanol as a raw material is supplied to a fixed bed reactor, it can be supplied together with water. The water concentration is preferably 0.5% by mass to 30% by mass as the composition at the inlet of the latter stage of the fixed bed reactor, that is, the composition after the isobutanol dehydration reaction. If it is too much or too little, the yield in the next oxidation reaction is lowered. Excess water also contributes to an increase in energy load during active ingredient recovery.

  It is preferable to evaporate the raw material and supply it to the fixed bed reactor. As an evaporator for evaporating, a jacket type, a natural circulation type horizontal pipe type, a natural circulation type submerged pipe type, a natural circulation type vertical short pipe type, There is no particular limitation such as a vertical long pipe rising film type, a horizontal pipe falling film type, a forced circulation horizontal pipe type, a forced circulation vertical pipe type, and a coil type.

  Considering the azeotropic composition of isobutanol / water, a kettle type evaporator such as a natural circulation type horizontal tube type or a natural circulation type vertical short tube type is preferable for preventing raw material loss and adjusting the water concentration.

  There are no particular restrictions on the raw water supply source and supply device, but it is preferable to evaporate water separately from isobutanol, and after mixing it is mixed with isobutanol separately evaporated to a fixed bed reactor. It is preferable to supply. In that case, it is preferable to evaporate without adding water to the evaporator for isobutanol.

  Isobutanol can be used in combination with other raw materials used in the production of methacrolein by the catalytic gas phase oxidation method, for example, isobutylene, t-butanol, methyl tertiary butyl ether and the like.

  In many cases, t-butanol is synthesized by a hydration reaction of isobutylene, then obtained by distillation purification, and obtained in an azeotropic composition with water.

  When t-butanol, which is the same alcohol component as isobutanol, is used in combination, the evaporator is, for example, a shelf, packed tower type, raw alcohol, raw water supply port, evaporated raw material extraction port and kettle liquid extraction A device having a mouth and a reboiler as a heating device can be used. Moreover, you may provide the preheater of each raw material and the super heater of the evaporated raw material as needed.

  When isobutanol and t-butanol are evaporated using one evaporator, the feed ratio of the raw water and the mixed alcohol defined by the formula (1) is preferably 0.05 or more by mass ratio, The following is preferred. If it is less than 0.05, the raw material isobutanol is mixed into the pot liquid, resulting in a loss. Moreover, when it becomes larger than 0.5, the waste water discharged | emitted from a kettle will increase.

Supply ratio of raw water and mixed alcohol = (mass flow rate of water supplied to the evaporator) / (mass flow rate of mixed alcohol supplied to the evaporator) (1)
Moreover, the isobutanol ratio in the mixed alcohol defined by the formula (2) is more than 0 and preferably 0.4 or less on a mass basis. When the mixing ratio is greater than 0.4, the amount of waste water discharged from the kettle increases.

Ratio of isobutanol in mixed alcohol = (mass flow rate of isobutanol supplied to the evaporator) / [(mass flow rate of isobutanol supplied to the evaporator) + (mass flow rate of t-butanol supplied to the evaporator) ]] (2)
When isobutanol and t-butanol are evaporated separately using a plurality of evaporators, it is preferable to evaporate water alone or together with t-butanol.

  As isobutanol and t-butanol are dehydrated and oxidized, methacrolein and methacrylic acid can be obtained efficiently.

  The isobutanol dehydration reaction in the previous stage may be performed according to a conventionally known method. In particular, it is preferable to use a dehydration catalyst such as an acid catalyst. Specific examples of the acid catalyst include alumina, silica alumina, solid phosphoric acid, titania, and zirconia. By using an acid catalyst in which one or two or more of these are used in combination, the dehydration reaction of isobutanol can be favorably performed. The subsequent oxidation reaction may be performed according to a conventionally known method. As a specific example of the oxidation catalyst, a catalyst component containing at least molybdenum, bismuth and iron as catalyst components and having a composition represented by the following general formula (3) is preferable.

Mo _a Bi _b Fe _c M _d X _e Y _f Z _g Si _h O _i (3)
(In the formula, Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively. M represents at least one element selected from cobalt and nickel. X represents chromium, lead and manganese. Represents at least one element selected from calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc, and Y represents at least selected from phosphorus, boron, sulfur, selenium, tellurium, cerium, tungsten, antimony and titanium. Z represents at least one element selected from lithium, sodium, potassium, rubidium, cesium and thallium, a, b, c, d, e, f, g, h and i are each Represents the atomic ratio of the elements. When a = 12, b = 0.01-3, c = 0.01-5, d = 1-12, e = 0-8, f 0 to 5, g = a 0.001 and h = 0 to 20, i is an oxygen atom ratio required for satisfying the valency of each component.)
The oxidation catalyst is preferably an oxide containing at least molybdenum, bismuth and iron as catalyst components. Other catalyst components include silicon, cobalt, nickel, chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum, zinc, phosphorus, boron, sulfur, selenium, tellurium, cerium, tungsten, It may contain antimony, titanium, lithium, sodium, potassium, rubidium, cesium, thallium and the like.

  Such an oxidation catalyst containing at least molybdenum, bismuth and iron is generally produced through [1] a step of producing particles containing a catalyst component and [2] a step of drying and / or heat treatment.

  The process [1] is not particularly limited, and various conventionally known methods can be applied. Usually, an aqueous slurry containing at least molybdenum, bismuth, and iron is dried and further pulverized into particles as necessary. The method for producing this aqueous slurry is not particularly limited, and various methods such as a well-known precipitation method and oxide mixing method can be used as long as there is no significant uneven distribution of components.

  As raw materials for the catalyst component dissolved in the aqueous slurry, oxides, sulfates, nitrates, carbonates, hydroxides, ammonium salts, halides, and the like of each element can be used. For example, examples of the molybdenum raw material include ammonium paramolybdate and molybdenum trioxide. The raw material of the catalyst component may be used alone or in combination of two or more for each element.

  In the step [2], the method of drying the aqueous slurry to form particles is not particularly limited. For example, a method of drying using a spray dryer, a method of drying using a slurry dryer, or a drum dryer. A drying method, a method of pulverizing a lump-like dried product by evaporation to dryness, and the like can be applied. Among these, a method of obtaining dry spherical particles using a spray dryer is preferable because particles can be obtained simultaneously with drying and the obtained particles have a spherical shape. Although the drying conditions vary depending on the drying method, when a spray dryer is used, the inlet temperature is usually 100 to 500 ° C, and the outlet temperature is usually 100 ° C or higher, preferably 105 to 200 ° C.

  The dried particles obtained in this way may contain a salt such as nitric acid derived from the catalyst raw material, etc., and if these salts are decomposed by firing after the molding of the particles, the strength of the molded product may be reduced. is there. For this reason, it is preferable that the particles are not only dried but also fired at this point to form fired particles. The firing conditions are not particularly limited, and known firing conditions can be applied. Usually, calcination is performed in the temperature range of 200 to 600 ° C. in the presence of oxygen, air, nitrogen, nitrogen oxides, etc., and the calcination time is appropriately selected depending on the target catalyst.

  The concentration of isobutanol in the raw material gas can be varied within a wide range, but is preferably 1 to 20% by volume. Although it is economical to use air as the molecular oxygen source, air or the like enriched with pure oxygen can be used if necessary. The molar ratio (volume ratio) of the reaction raw material and oxygen in the raw material gas is preferably in the range of 1: 0.5 to 1: 3. The raw material gas preferably contains water in addition to the reaction raw material and molecular oxygen, and is preferably diluted with an inert gas such as nitrogen or carbon dioxide. The water concentration in the raw material gas is preferably 1 to 45% by volume. The reaction pressure is preferably from normal pressure to several hundred kPa. The reaction temperature can usually be selected in the range of 200 to 450 ° C, but the range of 250 to 400 ° C is particularly preferable. The contact time is preferably 1.5 to 15 seconds.

  The apparatus used in such a method has a fixed bed reactor filled with a dehydration catalyst in the front stage and an oxidation catalyst in the rear stage, and performs dehydration and oxidation reaction by passing at least isobutanol through the fixed bed reactor, Any apparatus that can extract the reaction products methacrolein and methacrylic acid may be used. The structure of the fixed floor may be the same as that of the conventional apparatus. In the present invention, since methacrolein and methacrylic acid are directly produced by dehydrating and oxidizing isobutanol, the isobutanol dehydrating step is unnecessary. Therefore, it is not necessary to newly add an isobutylene production apparatus by single isobutanol dehydration. Therefore, for example, the conventional plant equipment that produced methacrolein and methacrylic acid by dehydration and oxidation reaction of t-butanol can be used as it is without remodeling to produce a methacrylic resin raw material from isobutanol. it can. Thus, the present invention is advantageous in terms of equipment cost.

  In the reaction product dehydrated and oxidized according to the above method, most of isobutanol is converted to methacrolein, and a part thereof is converted to methacrylic acid. The conversion of both may be adjusted as appropriate depending on the reaction conditions and the type of catalyst.

  Methacrolein is useful as a raw material for methacrylic acid. For example, methacrylic acid can be obtained by catalytic gas phase oxidation reaction of gas (such as air) containing methacrolein and molecular oxygen. And the methyl methacrylate which is one of the methacrylic resin raw materials is obtained by esterification reaction of methacrylic acid and methanol. A methacrylic resin can be obtained by polymerizing methyl methacrylate.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. In the following description, “parts” means parts by mass.

  Analysis of raw materials and products was performed using gas chromatography. The reaction rate of isobutanol and the selectivity of isobutylene to be produced, methacrolein and methacrylic acid are respectively defined as follows.

Reaction rate of isobutanol (%) = (mol number of reacted isobutanol) / (mol number of supplied isobutanol) × 100
Isobutylene selectivity (%) = (number of moles of isobutylene produced) / (number of moles of isobutanol supplied) × 100
Selectivity of methacrolein (%) = (number of moles of methacrolein produced) / (number of moles of isobutanol supplied) × 100
Selectivity of methacrylic acid (%) = (number of moles of methacrylic acid produced) / (number of moles of supplied isobutanol) × 100
Example 1
Using a fixed bed reactor filled with 1.5 parts of commercially available alumina (AL3992E, trefoil type, manufactured by BASF) as the dehydration catalyst in the front stage and 7.0 parts of the oxidation catalyst in the back stage, the isobutanol is 5 volumes. %, Oxygen 14 volume%, and nitrogen 81 volume% were fed at a space velocity of 0.30 s ⁻¹ and reacted to obtain methacrolein and methacrylic acid. The results are shown in Table 1.

The oxidation catalyst used in this example was specifically prepared by the following method. Add 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, 1.4 parts of potassium nitrate, 27.5 parts of antimony trioxide and 49.5 parts of bismuth trioxide to 1000 parts of pure water, and heat and stir. It was. Separately, 114.4 parts of ferric nitrate, 281.6 parts of cobalt nitrate and 42.1 parts of zinc nitrate were sequentially added and dissolved in 1000 parts of pure water to obtain a liquid B. Liquid B was added to liquid A to form an aqueous slurry. This aqueous slurry was aged at 80 ° C. for 1 hour, and then most of the water was evaporated. The obtained cake-like substance was dried at 120 ° C. and then fired at 300 ° C. for 1 hour in an air atmosphere to be crushed. Thereafter, the pressure-molded product was crushed, and among the crushed particles, a particle that passed through a sieve having an aperture of 2.36 mm and not passed through a sieve having an aperture of 0.71 mm was obtained. Particles of a specific size thus classified were again heat-treated at 510 ° C. for 3 hours in an air atmosphere, and used as a catalyst. The catalyst composition other than oxygen of the obtained catalyst was Mo ₁₂ W _0.1 Bi _0.9 Fe _1.2 Sb _0.8 Co _4.1 Zn _0.6 K _0.06 .

(Example 2)
Methacrolein and methacrylic acid were obtained in the same manner as in Example 1 except that the amount of the oxidation catalyst charged in the latter stage of the fixed bed reactor was changed to 10.0 parts. The results are shown in Table 1.

(Comparative Example 1)
An attempt was made to obtain methacrolein and methacrylic acid in the same manner as in Example 1 except that a fixed bed reactor charged with only 7.0 parts of the oxidation catalyst was used. The results are shown in Table 1.

[Evaluation]
As shown in Table 1, Example 1 was a method using a fixed bed reactor in which a dehydration catalyst was packed in the front stage and an oxidation catalyst was packed in the rear stage, so that the selectivity of methacrolein was high.

  On the other hand, since Comparative Example 1 uses a fixed bed reactor filled with only an oxidation catalyst, the selectivity of methacrolein was low and methacrylic acid was not obtained.

  The present invention is useful as a method for efficiently producing methacrolein and methacrylic acid, which are raw materials for methacrylic resins. And since methacrylic resin is excellent in properties such as transparency and weather resistance, it can be suitably used for many applications such as signboards, covers for lighting fixtures, aquarium tanks, and recently LED light guide plates for LED liquid crystal televisions. it can.

Claims (9)

In a process for producing methacrolein and methacrylic acid from isobutanol,
A method for producing methacrolein and methacrylic acid, wherein at least isobutanol is passed through a fixed bed reactor filled with a dehydration catalyst in the front stage and an oxidation catalyst in the rear stage.   The method according to claim 1, wherein the dehydration catalyst in the previous stage is an acid catalyst.   The method of claim 2, wherein the acid catalyst is an acid catalyst comprising alumina, silica alumina, solid phosphoric acid, titania or zirconia.   The method according to claim 1, wherein the subsequent oxidation catalyst is an oxide containing at least molybdenum, bismuth and iron.   The process of claim 1 wherein t-butanol is passed along with isobutanol through a fixed bed reactor.   The process according to claim 1, wherein the isobutanol passed through the fixed bed reactor is biomass-derived isobutanol.   An apparatus for producing methacrolein and methacrylic acid, comprising a fixed bed reactor for dehydrating and oxidizing isobutanol filled with a dehydration catalyst in the front stage and an oxidation catalyst in the back stage.   The apparatus of Claim 7 which does not have the isobutylene manufacturing apparatus by independent isobutanol dehydration.   A method for synthesizing methyl methacrylate from methanol and methacrylic acid obtained by the method according to claim 1.