KR102211625B1 - Method for preparing isobutene oligomer - Google Patents

Abstract

The present invention is to prepare isobutene oligomers from a C4 hydrocarbon stream containing isobutene. More specifically, isobutene is oligomerized using a fixed bed catalytic reactor filled with a catalyst, and components having 8 or more carbon atoms among the produced isobutene oligomers are recycled to the reactor to control the heat of reaction, and isobutene oligomers having 12 or more carbon atoms It relates to a method for producing an isobutene oligomer that increases selectivity.

Description

Method for preparing isobutene oligomer {Method for preparing isobutene oligomer}

The present invention relates to a method for producing an isobutene oligomer from a C4 hydrocarbon stream, wherein a sulfuric acid-treated zirconia catalyst is used to obtain an isobutene oligomer product having 8 or more carbon atoms (C8+), and a part of the isobutene oligomer product is recycled to the reactor to obtain heat of reaction. It is a technology to control the temperature and increase the yield of isobutene oligomers having 12 or more carbon atoms.

Among propylene, propane, isobutane, normal butane, 1-butene, 2-butene, 1,3-butadiene and isobutene produced in the naphtha pyrolysis process, in the case of the isobutene, through oligomerization and hydrogenation of the isobutene The produced isoparaffin, especially isoparaffin having 12 or more carbon atoms, has features such as high cleaning power, chemical stability, odorlessness, and low toxicity, and is used as a detergent, degreasing agent, paint and paint thinner, and diluent for polymer initiators. .

In general, in the isobutene oligomer manufacturing process, in order to increase the yield of the oligomer, some of the effluent obtained from the oligomerization reaction is separated and recycled to the reactor, or a cation exchange resin (Patent Publication No. 10-2006-0012317), zeolite. (Applied Catalysis A: General 337, 73, 2008), tungsten oxide supported zirconia (Applied Catalysis A: General 366, 299, 2009), sulfuric acid-treated titania (Catalysis Today 107-108, 707, 2005) isobutene oligomer preparation There have also been attempts to improve the catalyst.

However, the catalysts have a low selectivity of 70% or less or a short catalyst life of the isobutene oligomer having 12 carbon atoms, and even if the catalyst has high selectivity, only pure isobutene is used as a reactant, such as linear butene. There was no example of using a hydrocarbon stream from the naphtha pyrolysis process containing as a raw material, and the isobutene oligomer obtained in the oligomerization reaction was recycled to increase the yield of the isobutene oligomer having a target carbon number and control even the heat of the isobutene oligomerization reaction. There was no example of the process.

Isobutene oligomerization reaction heat (Reactive & Functional Polymers 45, 19, 2000) is -63.08 kJ/mol, when two isobutene reacts to produce C8 olefin, when three isobutene reacts to produce C12 olefin,- 91.22 kJ/mol, when four isobutenes react to produce C16 olefins, -143.66 kJ/mol is generated. On the other hand, when isobutene reacts with C8 olefins, the reaction heat is -28.04 kJ/mol, C16 Olefin has two pathways (when two C8 olefins react, when isobutene reacts to C12 olefin), and the heat of reaction is -17.5 kJ/mol and -52.44 kJ/mol, respectively, and the reaction heat between isobutene and isobutene It shows a considerably lower value compared to.

In addition, in the isobutene oligomerization reaction, the unreacted product or part of the product is recycled to suppress catalyst damage due to exothermic heat or the formation of coke.In general, the recycling is to recycle the unreacted isobutene to increase the oligomer yield. In order to suppress the heat generated during the oligomerization reaction, the hydrogenated saturated oligomer, which is a final product, is recycled.

On the other hand, the present invention is a method for obtaining isobutene oligomers having 12 or more carbon atoms in high yield while maintaining a long catalyst life by using a sulfuric acid-supported zirconia catalyst.Some of the oligomers having 8 or more carbon atoms By recycling the reactor to the reactor, it is possible to control the heat of reaction and increase the yield of isobutene oligomer having 12 or more carbon atoms.

An object of the present invention is to provide a method capable of efficiently increasing the yield of an isobutene oligomer having 12 or more carbon atoms while controlling the heat of reaction in a method for producing an isobutene oligomer.

In the present invention, as a reactant used in the oligomerization reaction of isobutene, a C4 (4 carbon number) hydrocarbon stream containing isobutene generated in a naphtha pyrolysis process is used, and the isobutene content contained in the stream is 10 wt. It is more than% (10-100wt%), and contains 1-butene, 2-butene, etc. in addition to isobutene. Producing an isobutene oligomer using 10 wt% or less of isobutene is difficult to secure process economics because the amount of isobutene oligomer produced per feed weight is small, and the isobutene content in the C4 hydrocarbon stream produced in a conventional naphtha pyrolysis process is 10%. Exceeds.

100% of the isobutene is converted to MTBE (methyl tertbutyl ether) or TBA (tert-butanol) by reacting the C4 hydrocarbon stream containing isobutene from the naphtha pyrolysis process with methanol or water, and the converted MTBE or TBA can be obtained purely and obtained by pyrolyzing it.

As the catalyst used in the oligomerization reaction, a catalyst having a sulfur content of 0.1 wt% or more in the sulfuric acid-treated zirconia catalyst was used, and more preferably, a catalyst having 0.1 to 3.0 wt% was used.

The oligomerization reaction can be batch type or continuous type, but a continuous type reaction using a fixed bed reactor is suitable.

Since the pyrolysis of sulfuric acid-treated zirconia occurs at 500°C or higher, the reaction temperature for oligomerization can range from room temperature to 500°C, and 50 to 200°C is suitable. When the temperature is lower than the room temperature, the catalytic reaction for oligomerization of isobutene is not properly performed, and when the temperature is higher than 500°C, thermal decomposition of the sulfuric acid-treated zirconia catalyst proceeds, thereby inhibiting the isobutene oligomerization reaction. In addition, the reaction pressure is preferably 15 bar or more, and the weight hourly space velocity (WHSV) is preferably 50h ^-1 or less.

Of the effluent obtained from the isobutene oligomerization reaction, a part of the isobutene oligomer effluent before hydrogenation having 8 or more carbon atoms is recycled to the reactor 2, thereby effectively reducing the heat of reaction due to isobutene oligomerization.

The isobutene oligomer prepared from the isobutene oligomerization reaction is a multiple of 4 having C8, C12, C16, C20, etc., and has one double bond in the chain of the prepared isobutene oligomer.

According to the present invention, in the production of isobutene oligomers, some oligomers having 8 or more carbon atoms among the isobutene oligomers produced by the oligomerization reaction are recycled to the reactor, thereby increasing the yield of oligomers having 12 or more carbon atoms, and simultaneously isobutene oligomerization. During the reaction, it is possible to suppress catalyst damage or coke formation due to heat generation.

1 is a schematic diagram of a process for the manufacturing method of the present invention.

Hereinafter, the present invention will be described in more detail through Examples and Comparative Examples, but the scope of the present invention is not limited by these Examples and Comparative Examples.

Examples and comparative examples of the present invention were carried out according to the above method, and the reaction was used by filling a commonly used fixed bed catalytic reactor 2 with a sulfuric acid-treated zirconia catalyst having a sulfur content of 0.1 to 3.0 wt%.

As a reactant, a C4 hydrocarbon stream (1) containing isobutene is introduced into a catalyst-filled reactor (2), the isobutene is converted to an oligomer in the reactor (2), and the converted oligomer product (3) is prepared. 1 Transfer to the distillation column (4), and recover unreacted isobutene and C4 hydrocarbons (5) by separating them overhead, and some oligomers (7) having 8 or more carbon atoms among the oligomers (6) having 8 or more carbon atoms separated from the bottom. ) Is recycled to the reactor (2).

[Example 1]

The reactant was a C4 hydrocarbon stream having an isobutene content of 75 wt%, and in the oligomerization reaction, sulfuric acid-treated zirconia (SZ-Fresh, manufactured by Alfa Aesar) containing 0.1 to 3.0 wt% sulfur was used as a catalyst.

The catalyst was charged to the reactor 2, and the C4 hydrocarbon stream 1 was injected upflow, the reaction temperature of the reactor 2 was maintained at 70° C., and the pressure was maintained at 15 bar, The reactant was charged so that WHSV=1.0h ^-1 based on the total content of the C4 hydrocarbon stream.

After the initiation of the reaction, the liquid product and unreacted gas were collected every hour and the composition was analyzed by GC (Gas Chromatography).As a result of the reaction, the isobutene conversion rate gradually increased after the reaction, maintaining more than 99% after 12 hours. For, C8 oligomer 12.8% and C12+ oligomer 87.2% were shown, and the reaction conditions and isobutene oligomer selectivity for each carbon number are summarized in Table 1.

[Example 2]

The reaction of Example 1 was carried out using a hydrocarbon mixture stream having 20 wt% of C4 hydrocarbons, 60 wt% of isobutene and 20 wt% of C8+ isobutene oligomers, instead of a C4 hydrocarbon stream having an isobutene content of 75 wt%. With respect to the product as a whole, C8 oligomer 11.5% and C12+ oligomer 88.5wt% were shown, and in particular, C20+ oligomer selectivity was greatly increased to 5.1wt%, so the production of oligomers of 12 or more carbon atoms increased by using oligomers with 8 or more carbon atoms as reactants. It was confirmed that the reaction conditions and the selectivity of the isobutene oligomer for each carbon number are summarized in Table 1.

[Comparative Example 1]

The reaction of Example 1 was carried out using a hydrocarbon stream in which 10 wt% of isobutene and 90 wt% of normal butane were mixed instead of a C4 hydrocarbon stream having an isobutene content of 75 wt%, and as a result of the reaction, C8 It showed 17.6% oligomer and 82.4% C12+ oligomer, and the reaction conditions and isobutene oligomer selectivity for each carbon number are summarized in Table 1.

[Comparative Example 2]

The reaction of Example 1 was carried out using 100 wt% of isobutene content instead of a C4 hydrocarbon stream having an isobutene content of 75 wt%, and as a result of the reaction, C8 oligomer 14.5% and C12+ oligomer 85.5% were shown. , Reaction conditions and isobutene oligomer selectivity for each carbon number are summarized in Table 1.

[Example 3]

The reaction of Example 1 was carried out using a hydrocarbon mixture stream having an isobutene content of 17 wt% and a C8+ isobutene oligomer content of 16 wt% instead of a C4 hydrocarbon stream having an isobutene content of 75 wt%.As a result of the reaction, with respect to the entire reaction product, C8 oligomers showed 8.6% and C12+ oligomers 91.4%, and in particular, C20+ oligomer selectivity increased to 8.6%, so it was confirmed that the amount of oligomers having 12 or more carbons increased by using oligomers having 8 or more carbons as a reactant. And isobutene oligomer selectivity for each number of carbon atoms is summarized in Table 1.

Experiment Isobutene NC4 C8+ oligomer Total WHSV selectivity wt% wt% wt% h ^-1 C8 C12 C16 C20+ Example 1 75 25 0 1.0 12.8 62.3 20.4 4.5 Example 2 60 20 20 1.0 11.5 62.8 20.6 5.1 Comparative Example 1 10 90 0 1.0 17.6 60.8 19.0 2.6 Comparative Example 2 100 0 0 1.0 14.5 60.3 20.5 4.7 Example 3 17 67 16 2.5 8.6 62.4 20.4 8.6

※ NC4: C4 hydrocarbon

1: C4 hydrocarbon stream
2: reactor
3: oligomer product
4: first distillation column
5: unreacted isobutene and C4 hydrocarbon
6: C8 or more (C8+) isobutene oligomer
7: Some C8 or higher (C8+) isobutene oligomers

Claims (5)

As a method for producing an isobutene oligomer that oligomerizes a C4 (4 carbon number) hydrocarbon stream generated in a naphtha pyrolysis process containing isobutene using sulfuric acid-treated zirconia as a catalyst,
Some of the isobutene oligomers having 8 or more carbon atoms among the prepared isobutene oligomers are recycled to the C4 hydrocarbon stream to contain 17 to 60 wt% of isobutene and 16 to 20 wt% of the recycled isobutene oligomer having 8 or more carbon atoms Forming a mixture stream,
A method for producing an isobutene oligomer, characterized in that to prepare an isobutene oligomer having a selectivity of 5 to 9% of an isobutene oligomer having 20 or more carbon atoms with respect to the total reaction product produced by oligomerizing the hydrocarbon mixture stream. The method of claim 1, wherein the content of isobutene in the C4 (4 carbon atoms) hydrocarbon stream is more than 10 wt%, and contains 1-butene and 2-butene. The method for producing an isobutene oligomer according to claim 1, wherein the sulfuric acid-treated zirconia catalyst has a sulfur content of 0.1 wt% or more. The preparation of an isobutene oligomer according to claim 1, wherein the oligomerization has a reaction temperature of 50 to 200°C, a pressure of 15 bar or more, and a weight hourly space velocity (WHSV) of 50 h ^-1 or less. Way. The method of claim 1, wherein the prepared isobutene oligomer is a multiple of 4 having 8, 12, 16, and 20 carbon atoms, and has one double bond to the prepared isobutene oligomer. .

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