JP5290937B2 - Method for producing alcohol - Google Patents

Description

The present invention relates to a method for producing an alcohol by hydration of olefins using an ion exchange resin as a catalyst.

  As a method for producing an alcohol by an olefin hydration reaction using an ion exchange resin as a catalyst, for example, Patent Documents 1 to 6 disclose a method for producing a tertiary butyl alcohol (hereinafter referred to as TBA) by an isobutylene hydration reaction. Have been described.

  In the isobutylene hydration reaction, the mutual solubility of the raw material isobutylene and water is low, and the reaction solution forms two phases of an organic phase and an aqueous phase, so that the reaction rate is generally slow. Thus, a method for improving the reaction rate by devising the reaction solvent to make the reaction solution uniform has been proposed. As a method of devising such a solvent, for example, Patent Document 2, Patent Document 3, Patent Document 6, and Patent Document 7 use an alcohol, Patent Document 4 uses a polar solvent, and Patent Document 1 uses an organic acid. And Patent Document 5 includes a method using Glycol.

  The ion exchange resin used as a catalyst for the olefin hydration reaction is usually handled in a wet state with water due to strength problems, and the water content at that time is usually 45 to 65% by weight. Regarding the ion exchange resin and water, Patent Document 2 and Patent Document 3 describe that the ion exchange resin to be used is preferably sufficiently swollen with water first and then used for the hydration reaction. It is mentioned that the by-product of the polymer is suppressed and that the deterioration of the activity of the catalyst is greatly improved.

Japanese Patent Publication No. 60-05451 Japanese Patent Laid-Open No. 55-085529 JP-A-55-108825 JP 56-034643 A JP 56-087526 A Japanese Patent Publication No. 03-042250 Japanese Patent Laid-Open No. 56-010124

  However, when an ion exchange resin wetted with water is used as a catalyst for the production of alcohol by hydration of olefins, it takes a long time to obtain a predetermined conversion rate in both batch operation and continuous operation. There was a problem of low nature.

  Accordingly, an object of the present invention is to provide a method for producing an alcohol with high productivity by hydration of olefins using an ion exchange resin as a catalyst.

The present invention is a method for producing alcohol by olefin hydration using a fixed bed reactor using an ion exchange resin as a catalyst. The ionic exchange resin in the state is brought into contact with the reaction solvent and / or the same kind of alcohol as the product of the hydration reaction, the water concentration in the solvent contained in the ion exchange resin is reduced to 80% by weight or less, and then the olefin is supplied. And the hydration reaction is started.

  According to the present invention, when an alcohol is produced by hydration of an olefin, the alcohol can be produced with high productivity.

  In the present invention, examples of the method for producing an alcohol by olefin hydration include, for example, a method for producing TBA from isobutylene, a method for producing secondary butyl alcohol from normal butene, and the like. It is not a thing.

The ion exchange resin used as a catalyst in the present invention is preferably a porous strongly acidic cation exchange resin having a styrene / divinylbenzene copolymer as a skeleton. In particular, the surface area measured by using the BET method with nitrogen for 7 hours under vacuum at 80 ° C. is 10 to 100 m ² / g, according to the method described in “Chemical and Industrial” Vol. 21, No. 11, 1465 (1968). The measured pore volume is 0.1 to 1.0 ml / g, the particle size measured using a JIS Z 8801-1981 (standard mesh sieve) sieve is 0.1 to 2 mm, and the apparent density is measured by the mercury intrusion method. The exchange capacity representing the milligram equivalent of the sulfonic acid group per 1 g of the catalyst dry particles is 1.0 meq / g or more, and the addition amount of divinylbenzene as a crosslinking agent is the mass relative to the monomer styrene. A strongly acidic cation exchange resin having a degree of cross-linking expressed by a ratio of 8 to 18% is preferable. Examples of such strongly acidic cation exchange resins include “Lebatit” (trade name) manufactured by Bayer, “Amberlyst” (trade name) manufactured by Rohm and Haas, and the like.

  In the present invention, the ion exchange resin is brought into contact with the reaction solvent and / or the same type of alcohol (hereinafter referred to as a pretreatment agent) (hereinafter referred to as pretreatment) before being used in the hydration reaction. At this time, the pretreatment agent is preferably used in an aqueous solution. In addition, in order to remove impurities present in the pores of the ion exchange resin, it is preferable that the ion exchange resin and pure water are sufficiently in contact before the pretreatment.

  Examples of the method for pretreating the ion exchange resin include a method of immersing the ion exchange resin in the pretreatment agent, a method of passing the pretreatment agent through a reactor filled with the ion exchange resin, and the like. Is not to be done. In particular, it is preferable to perform the pretreatment in a reactor for carrying out the hydration reaction because a series of operations from the pretreatment to the reaction can be simplified.

  Usually, the pretreatment is performed in a temperature range of 20 to 70 ° C. at a pressure at which the pretreatment agent does not vaporize.

  In the present invention, an alcohol is produced by an olefin hydration reaction using the ion-exchange resin thus pretreated as a catalyst. Examples of the raw material olefin include isobutylene and normal butene. When isobutylene is used as the olefin, a liquefied gas composed of isobutylene alone and isobutylene-containing hydrocarbon (hereinafter referred to as liquefied gas) or the like can be used as the isobutylene source. Examples of the isobutylene-containing hydrocarbon include a mixture of butenes containing isobutylene, butanes, and the like. As such an isobutylene source, industrially, a C4 hydrocarbon mixture obtained by thermal cracking, steam cracking, catalytic cracking or the like of petroleum is used, but a butadiene is preferably separated and removed therefrom. Such industrially available isobutylene-containing hydrocarbons usually have a concentration of 80% by weight or less of isobutylene, but in the present invention, 15-50% by weight of isobutylene-containing hydrocarbons, which are easily available, are preferred.

  In the present invention, the hydration reaction can be carried out either batchwise or continuously. The structure type of the reactor used in this case is not particularly limited as long as it is capable of solid-liquid contact, such as a tube type or a column type, and is not particularly limited (hereinafter referred to as a fixed bed type reactor). One reactor or two or more reactors may be connected. As such a reactor, for example, a reactor in which continuous flow type fixed bed reactors are arranged in multiple stages in series can be used.

  In the present invention, as a reaction solvent used in the hydration reaction, polar solvents such as organic acids, sulfones, sulfolanes and sulfolenes, aliphatic alcohols having 1 to 8 carbon atoms, glycol and the like can be used. In addition, the product alcohol may be used as the reaction solvent. In this case, a separately prepared alcohol may be used, but it is convenient to use the alcohol generated by the hydration reaction of the present invention.

When using a serial multistage reactor, it is preferable to add alcohol as a product to the first reactor as a solvent because there is an effect of suppressing an increase in adiabatic temperature in the reactor after the second reactor. In the serial multistage reactor, a part of the outlet reactant of the first reactor is circulated to the inlet of the first reactor so that a part of the alcohol produced in the first reactor can be used as a solvent. . The circulation ratio when a part of the outlet reactant of the first reactor is circulated to the inlet of the first reactor is defined as follows.
Circulation ratio = (circulation amount) / (raw material supply amount + TBA supply amount + circulation amount)
Here, the circulation amount is the circulation amount of the outlet reaction product of the first reactor per unit time, the raw material supply amount is the supply amount of isobutylene or isobutylene-containing hydrocarbon and water per unit time, and the TBA supply amount is the unit. This is a TBA supply amount newly added from the outside per hour and does not include TBA contained in the circulating fluid. These are all by weight.

  When producing TBA from isobutylene, the circulation ratio is preferably 1.8 to 10, and particularly preferably 2 to 5. By adopting such a circulation ratio, even when a small amount or zero of TBA is newly added from the outside, the reaction solution at the inlet of the first reactor can be made to be uniform. In addition, it is preferable to circulate the outlet reactant of the first reactor because it has an effect of suppressing an increase in the adiabatic temperature of the first reactor due to a hydration reaction that is an exothermic reaction.

  Further, when TBA is produced from isobutylene using a series multistage reactor, the weight ratio of TBA to liquefied gas at the inlet of the first reactor is preferably 0.5 to 3.5, particularly 0.8 to 3 Is preferred. By adjusting the circulation ratio and the amount of TBA newly added from the outside so as to achieve such a weight ratio, a reaction rate that is sufficiently satisfactory industrially can be obtained even if the reaction solution is not uniform. The weight ratio of TBA to liquefied gas at the inlet of the first reactor can be adjusted to a preferable range by adding TBA newly added from the outside without circulating through the first reactor, but the hydration of isobutylene and water. The TBA synthesis reaction by reaction is an equilibrium reaction, and adding a large amount of product TBA from the outside to the reaction system has a problem in equilibrium.

  In the present invention, the reaction temperature of the hydration reaction varies depending on conditions such as the type and amount of raw materials used, the solvent, the type of reactor, etc., but it cannot be generally stated. For example, TBA is converted from isobutylene using a series multistage reactor. When manufacturing, it is preferable to carry out reaction temperature of all the reactors at 65 degrees C or less normally. The reaction temperature refers to the temperature of the highest temperature part in the reactor.

  In the present invention, the reaction pressure of the hydration reaction is a pressure at which the raw olefin and water are in a liquid state at the reaction temperature, and this pressure is usually 200 to 5000 kPa.

  According to the present invention, when an alcohol is produced by an olefin hydration reaction using a pretreated ion exchange resin, a predetermined conversion rate can be obtained in a shorter time than when no pretreatment is performed. . The present inventors estimate the reason why such an effect is obtained as follows. That is, a part or all of the preexisting water is replaced with the pretreatment agent by the mutual diffusion action inside the pores of the ion exchange resin in the pretreatment. As a result, it is presumed that the mutual solubility between the raw material olefin and the liquid inside the pores is improved, and the diffusion of the olefin to the active sites inside the pores of the ion exchange resin is facilitated.

  The present invention will be described below with reference to examples and comparative examples. In addition, gas chromatography equipped with a capillary column was used for quantitative analysis of the raw material isobutylene-containing hydrocarbon, water, TBA produced, and impurities such as isobutylene dimer and secondary butyl alcohol.

The conversion rate of isobutylene to TBA (hereinafter simply referred to as conversion rate) was calculated by the following equation.
Conversion rate (%) = (A−B) / A
Here, in Example 1 and Comparative Example 1 in which the reaction was carried out by batch operation, A is the number of moles of isobutylene charged into the reaction system before the reaction, and B is the mole of isobutylene remaining in the reaction system after the reaction. Represents a number. In Examples 2, 3 and Comparative Example 2 in which the reaction was carried out continuously, A represents the number of moles of isobutylene supplied into the reaction system, and B represents the number of moles of isobutylene discharged from the reaction system. .

  The production rate (g / h) of each compound refers to the average production amount of the compound per unit of g per hour.

[Example 1]
Using the reaction apparatus shown in FIG. 1, TBA was produced by hydration of isobutylene. The reactor 3 is a cylindrical reactor having an inner diameter of 40 mm and an internal volume of 400 ml. The reactor 3 is provided with a jacket, and has a structure in which a heat medium can be circulated so as to reach a predetermined reaction temperature.

  The reactor 3 is filled with 350 ml of a strongly acidic ion exchange resin “Amberlyst 15WET” (trade name) manufactured by Rohm and Haas, and 1750 ml of pure water at 30 ° C. is charged before the hydration reaction. The ion exchange resin was washed by passing through the reactor. Further, 1750 ml of a 40 wt% TBA aqueous solution at 30 ° C. was passed through. The concentration of the TBA aqueous solution contained in the ion exchange resin after passing through was 20% by weight.

  Next, the reaction liquid consisting of 480 g of the isobutylene-containing hydrocarbon having the composition shown in Table 1 previously charged in the raw material tank 1, 231 g of water and 316 g of TBA was reacted at a linear velocity of 10 mm / s based on the superficial value in the reactor. The reaction was carried out at a reaction temperature of 65 ° C. and a reaction pressure of 1160 kPa. The conversion of isobutylene 5 hours after the start of the reaction was 65%, and the amount of TBA produced at this time was 198 g.

[Comparative Example 1]
TBA was produced in the same manner as in Example 1 except that the aqueous TBA solution was not passed through the ion exchange resin before the hydration reaction. The conversion of isobutylene after 5 hours from the start of the reaction was 35%. The amount of TBA produced at this time was 105.5 g.

[Example 2]
Using the reaction apparatus shown in FIG. 2, TBA was produced by hydration of isobutylene. Each reactor was a cylindrical reactor having a diameter of 52.7 mm and an internal volume of 12 L. Three reactors were used in series.
Each reactor was filled with 12 L of strongly acidic cation exchange resin “K-2621” (trade name) manufactured by Bayer and washed by passing pure water through LHSV = 1h-1 for 2 hours. Simultaneously with this operation, an operation for raising the temperature of the reactor from room temperature to the reaction temperature was started.
Following the passage of pure water, an 86.5% by weight aqueous TBA solution was passed for 4 hours at LHSV = 1h-1. The concentration of the TBA aqueous solution contained in the ion exchange resin after passing through was 20% by weight.

  Subsequently, the isobutylene-containing hydrocarbon having the composition shown in Table 2 was supplied to the first reactor 4 at 2.8 kg / h and water at 0.6 kg / h, and the first reactor 4 to the third reactor 10 The reaction was carried out at 59 ° C, 62 ° C and 59 ° C, respectively. Also, TBA, which is a reaction product, is added to the first reactor 4 so that the weight ratio of TBA to liquefied gas at the inlet of the first reactor 4 is 0.8, and one of the outlet reactants of the first reactor 4 is The circulation ratio when the part was circulated to the first reactor 4 was 3.2.

  The conversion rate 8 hours after the start of the reaction was 84.4%. At this time, the production rate of TBA was 1403 g / h, the production rate of isobutylene dimer was 0.2 g / h, and the production rate of secondary butyl alcohol was The yield was 0.6 g / h, and the amount of isobutylene dimer and secondary butyl alcohol produced was extremely small.

[Comparative Example 2]
When TBA was produced in the same manner as in Example 2 except that the time for washing with pure water in the ion exchange resin before the hydration reaction was 6 hours and the TBA aqueous solution was not passed, The conversion rate 8 hours after the start of the reaction was 75%. At this time, the production rate of TBA was 1247 g / h, the production rate of isobutylene dimer was 0.2 g / h, and the production rate of secondary butyl alcohol was 0.2%. It was 4 g / h, the conversion rate and the isobutylene production rate were low, and the productivity was poor.

An example of a reactor used when carrying out the present invention by batch operation An example of a reactor used when carrying out the present invention in a continuous operation

1 Raw material tank 2 Circulation pump 3 Reactor 4 First reactor 5 Pump 6 Heat exchanger 7 Heat exchanger 8 Second reactor 9 Heat exchanger 10 Third reactor 11 Olefin source supply pipe 12 Water supply pipe 13 Solvent supply Tube 14 First reactor inlet 15 First reactor outlet

Claims (1)

In a method of producing alcohol by olefin hydration using a fixed bed reactor using an ion exchange resin as a catalyst, as a pretreatment of the hydration reaction, ion exchange in a state sufficiently in contact with pure water The resin is brought into contact with the reaction solvent and / or the same kind of alcohol as the product of the hydration reaction, and the water concentration in the solvent contained in the ion exchange resin is reduced to 80% by weight or less. A method for producing an alcohol, comprising starting a reaction.

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