JPS6043049B2 - Method for purifying n-butene - Google Patents

Description

Detailed Description of the Invention (a) Background Technical Field of the Invention The present invention relates to the treatment of n-butene fraction with macroporous cations in the presence of water and/or tertiary butyl alcohol (hereinafter abbreviated as TBA). The present invention relates to a method for purifying n-butene by contacting with an exchange resin to convert isobutene in the n-butene fraction into a low polymer, and then separating the low polymer of isobutene.

N-butene is used as a raw material for useful petrochemical products such as secondary butyl alcohol and methyl ethyl ketone, or as a copolymer component with α-olefins such as ethylene.

As a method for industrially producing n-butene, isobutene is recovered by a sulfuric acid method and then separated and recovered from an n-butene fraction. However, in this method, since the reaction of sulfuric acid to isobutene is not completely selective, isobutene remains in the n-butene fraction. It was difficult to obtain. In addition, as a method for separating isobutene without using an aqueous sulfuric acid solution, for example, isobutene is separated as a low polymer by contacting a Cl hydrocarbon mixture with a solid catalyst such as silica/alumina, molecular sieve, zeolite, activated clay, or acidic cation exchange resin. Alternatively, a Cl hydrocarbon mixture is treated in the presence of a solid acid catalyst such as a cation exchange resin, silica/alumina, or a phosphoric acid supported catalyst, or an acid aqueous solution to react isobutene with water, alcohol, or an organic acid, etc. to produce TBA. ) A method of separating and recovering tertiary butyl ether, butyl ester, etc. is known.

However, the n-butene fraction obtained after separating and recovering these isobutenes also contains residual isobutene, so the content of isobutene is extremely low when it comes to n-butene used as a raw material for petrochemical products such as those mentioned above. need to be lower. Furthermore, solid catalysts for carrying out the low polymerization reaction of isobutene have a problem of short catalyst life. (2
) Summary of the Invention The present invention aims to solve the above-mentioned problems by bringing n-butene 7 fractions into contact with a macroporous cation exchange resin in the presence of water and/or TBA. The goal is to achieve this goal.

That is, the method for purifying n-butene according to the present invention
By contacting the butene fraction with a macroporous cation exchange resin in the presence of water and/or TBA, the n
- A method for purifying n-butene, which comprises polymerizing isobutene contained in the butene fraction to form a low polymer, and then separating it from the n-butene fraction. Effects By contacting the n-butene fraction with a macroporous cation exchange resin in the presence of water and/or TBA, the selectivity for low polymerization of isobutene is improved, and the loss of n-butene is reduced. Catalyst life is also extended.

Since this reaction is carried out regardless of the content of isobutene in the n-butene fraction, it is easy to separate isobutene as a low polymer. In addition, since most of 1-butene is isomerized to 2-butene at the same time as isobutene is underpolymerized, a complicated multi-stage isomerization step is not required to substantially obtain 2-butene. The method of the present invention can also be applied to isobutene separation and recovery steps, such as equilibrium reactions such as separation of isobutene into a C4 hydrocarbon mixture by conversion to TBA by sulfuric acid method or direct hydration, or conversion to tertiary butyl ether by etherification. By combining this with the process of performing isobutene, the amount of isobutene remaining in the n-butene fraction can be extremely reduced, so there is no need to perform the isobutene separation process in multiple stages, eliminating the need for complex processes and can save energy.

n-. thus separated by the method of the present invention. The butene fraction has extremely high purity, and there is little loss of the n-butene fraction, making it highly economical.

(3) Detailed Description of the Invention N-Butene Fraction Starting material for the n-butene fraction used in the present invention. for,
Isobutene, 1-butene, Trans-2-butene, C
A C4 hydrocarbon mixture containing is-2-butene, isobutane, n-butane, etc. is used, but there are no particular limitations on its production method or the content of its components.

In addition, in the present invention, the n-butene fraction obtained after separating and recovering isobutene from the above C4 hydrocarbon mixture, for example, the n-butene fraction obtained after recovering isobutene in the C4 hydrocarbon mixture by a sulfuric acid method, C4 An n-butene fraction obtained by reacting isobutene in a hydrocarbon mixture with water in the presence of an acidic cation exchange resin and a neo-type polyhydric alcohol, an oxyacid, a sulfone, or a derivative thereof and separating and recovering TBA, or It is particularly preferable to use an n-butene fraction obtained by reacting isobutene in a C4 hydrocarbon mixture with an alcohol in the presence of an acidic cation exchange resin and separating and recovering tertiary butyl ether. And these C
The 4-hydrocarbon mixture may contain some amount of C3, C5 hydrocarbons. Generally, the C4 hydrocarbon mixture as the starting material is supplied industrially from C4 obtained after extracting and recovering butadiene from the C4 fraction obtained by steam cracking of naphtha, or from a fluid catalytic cracker for petroleum. This is done from the by-product C4 fraction etc.

The water and/or TBA used in the present invention can be present by being added to the n-butene fraction or by being added together with the n-butene fraction to a reactor filled with a cation exchange resin.

In addition, n- obtained after performing the hydration reaction of isobutene
Naturally, an n-butene fraction containing water and/or MA from the viewpoint of the process, such as a butene fraction, can be used as is. If the total amount of water and/or TBA present in the reaction system exceeds 25 mol% based on the n-butene fraction, the conversion rate and selectivity of isobutene will be low; If it is less than that, the catalyst life will be shortened, which is not preferable. Therefore, the amount of water or/and TBA present is 0.1 to 25 mol%, preferably 0.
．． A range of 2 to 20 mol%, particularly 1.0 to 17 mol% is preferred. Furthermore, although it is not clear how the effects of the presence of water and/or TBA in the reaction system are known, water mainly controls the acid strength of the reaction system through solvation, and also increases the affinity of hydrocarbons to cation exchange resins. In order to appropriately control it is conceivable that.

Macroporous cation exchange resin The macroporous cation exchange resin used in the present invention is preferably a strongly acidic cation exchange resin. For example, a copolymer of styrene and divinylbenzene is used as a core, and a sulfone Sulfonated styrene-divinylbenzene copolymer containing acid groups, sulfonated phenol-formaldehyde resin containing sulfonic acid groups in the condensation of phenol and formaldehyde, or sulfonic acid in the copolymer of fluorinated vinyl ether and fluorocarbon. In terms of its geometric structure, it is a gel-type ion exchange resin with physical pores added to it, and in its swollen state, the resin forms a chemical structural network. (microbore) and physical pore (
It is a porous ion exchange resin with macropores.

The exchange capacity of macroporous cation exchange resins is the same as that of gel-type cation exchange resins, or is reduced only by the macropores, but the reaction rate (catalytic activity) is very fast, and the catalyst The amount used is small, the reactor can be made smaller, and the macrobore portion acts as a cushion for volume changes, so it has excellent physical durability. This macroporous cation exchange resin has an exchange capacity of 2.0 meq/V (dry state) or more, especially 3.0 meq/V (dry state).
~6.0 milliequivalent/y, specific surface area (BET method) 0.2d
Iy (dry state) or more, especially 0.5 to 600 Iyl, and porosity 0.02 m1 Iy (dry state) or more, especially 0.
It is preferable that it is 1-0.7m11y. As described above, macroporous cation exchange resins have characteristics different from conventional gel type cation exchange resins.

A typical commercially available macroporous cation exchange resin is Amperlyst 15s Amperlyte 200C.
1 Amperlite IR-252, Dowex MSC-
1.Diaion HPK2\Diaion HPK4O (
Examples include Amperist, Amperlite, Dowex, and Diaion (trade names). Reaction Conditions In the reaction of the present invention, an n-butene fraction and water or/and TBA in a range of 0.1 to 25 mol%, preferably 0.2 to 20 mol%, based on the n-butene fraction. Supplied into a reactor filled with macroporous cation exchange resin.

The reaction temperature is 60 to 150°C, particularly preferably 80 to 130°C. In addition, the reaction pressure is a pressure that can maintain the n-butene fraction in a liquid phase under the reaction conditions, and is usually 5 to 50k91c! I
It is G. The n-butene fraction has a liquid phase space velocity (LHS)
) 0.1-10V 1 hrIV is fed to the reactor in upflow or downflow, preferably upflow. Contact between the n-butene stream and the macroporous cation exchange resin is usually carried out in a fixed bed system, but it can also be carried out in a moving bed system or a suspended bed system if necessary. Example 1 Macroporous cation exchange resin of sulfonated styrene/divinylbenzene copolymer (exchange capacity 4.3
Milliequivalent/y1 specific surface area 39.6y1y, porosity 0.3
A C4 hydrocarbon mixture (isobutene 3.5 mol%, 1-butene 48.9
% by mole, 4.7 mol % of 2-butene, 42.9 mol % of butanes) and water or/and TBA were supplied and brought into contact under the reaction conditions shown in Table 1 to carry out a low polymerization reaction of isobutene.

As a result of analyzing the obtained product with a gas chromatograph,
It was found that isobutene in the C4 hydrocarbon was converted to a low polymer mainly composed of diisobutene, and that most of the 1-butene was isomerized to 2-butene. The conversion rate of TBA, isobutene content in the reaction product, loss of total n-butene, and % of 1-butene in total l-butene obtained from the experimental results are also listed in Table 1 (experiment numbers 1 to 1). 8). For comparison, the experimental results in the above case where water or TBA is not present or where the amount of water or water and TBA is 30 mol% or more based on the n-butene fraction are also listed in Table 1 as a comparative example. (Experiment numbers 9 to 12).

Example 2 A C4 hydrocarbon mixture (isobutene 2.9 mol%
, 1-butene 45.2 mol%, 2-butene 5.6 mol%
, butanes (46.3 mol %), 2.1 mol % water and TBAl. O mol % and LHSVO. feeding at a rate of 8VIhrIV;
A low polymerization reaction of isobutene was carried out at a temperature of 110° C. and a pressure of 25 k91 d.

The reaction products were analyzed in the same manner as in Example 1, and the results are also listed in Table 2 (Experiment Nos. 13 to 17). For comparison, the experimental results for the case where a gel type cation exchange resin was used instead of the macroporous type are also listed in Table 2 as a comparative example (experiment numbers 18 and 19).

Example 3 Macroporous cation exchange resin of sulfonated styrene/divinylbenzene copolymer (exchange capacity 4.2
Milliequivalent/q1 Specific surface area 52dIy1 Porosity 0.38m
The C4 hydrocarbon mixture shown in Table 3 was added to a vertical reactor filled with LIy), and 4 liters of water was added to this C4 hydrocarbon mixture.
．． 0 mol% and TBAO. LHS by adding 5 mol%
Vl. Delivered at a rate of OVlhrIV and at a temperature of 115°C.
A low polymerization reaction of isobutene was carried out under the conditions of 1 pressure and 30 k91 cI.

Claims (1)

[Claims] 1. By bringing the n-butene fraction into contact with a macroporous cation exchange resin in the presence of water or/and tertiary butyl alcohol, the isobutene contained in the n-butene fraction is polymerized to reduce the polymerization. A method for purifying n-butene, comprising coalescence and subsequent separation from an n-butene fraction.