Method for preparing polybutene

A kind of method for preparing polybuteneTechnical field

[0001] The present invention relates to a method for preparing polybutene, and more specifically, to a method for economically preparing high-quality polybutene with low fluorine content and high vinylidene content under a high durability (ndleage) catalyst. Methods.

Background technique

[0002] Polybutene is a polymer produced from a C4 olefin billet containing 4 carbon atoms formed during a cracking process in the presence of a Friedel-Craft type catalyst. The number average molecular weight (Mn) of polybutene is about 300-5000. The raw material remaining after 1,3-butadiene is extracted from the C-4 billet produced by the refinery or naphtha cracking center (NCC) involved in cracking crude oil The material contains alkane blanks such as isobutane or n-butane and alkene blanks such as 1-butene, 2-butene, isobutene and the like. The isobutylene content of the raw material is about 20-50wt%. Isobutylene is mainly used in the preparation of methyl tert-butyl bromide (MTBE) or polybutene as an octane enhancer. Since isobutylene is the most reactive one among the olefin billets, polybutene is mainly produced from isobutylene units. Conventionally, polybutene has been used in a gluing agent, adhesive or release oil, and polybutene with low reactivity is preferred. This low-reactivity polyisobutylene is called "conventional PIB". In recent years, polybutenes with polar groups have been increasingly used in engine oil anti-scuff agents, viscosity index improvers, or detergents used in combination with automobile internal combustion engine fuels. This highly reactive polyisobutene is called "highly reactive polyisobutene (HR-PIB)".

[0003] One of the most popular products obtained by introducing polar groups into polybutene is polyisobutylene succinate (PIBSA) prepared by the reaction of polybutene and maleic acid. It can be prepared from PIBSA Various lubricating additives or fuel cleaners. In the preparation of PIBSA, since the double bond of polybutene is located at the farthest end of polybutene, that is, polybutene is highly reactive polyisobutene (HR-PIB), polybutene can be directly reacted with Malay Xuan to form high yield PIBSA_OConversely, when polybutene is a conventional PIB with relatively low reactivity due to the polybutene double bond located on the inner side and many alkyl groups as substituents that cause steric hindrance, the polybutene must be chlorinated with chlorine And react it with Malayan to produce PIBSA_O

[0004] In order to improve the reactivity of the polybutene, the polymerization conditions of the polybutene are controlled so that the polybutene has a double bond at the farthest end of the polybutene as far as possible. The double bond at the end of the polybutene is called "vinylidene". A compound with a vinylidene content of 70% or more is a "highly reactive polyisobutylene", a compound with a vinylidene content of about 40-70% is a "medium reactive vinylidene polyisobutylene (MV-PIB), and Compounds with vinylidene content of 3-40% are conventional polyisobutenes. The choice of catalyst and co-catalyst is very important for the control of polybutene reactivity. Generally speaking, the catalyst is boron trifluoride (BFJ, the co-catalyst is alcohol In addition, aluminum trichloride (A1C1J) can be used as a catalyst in the synthesis of polybutene whose double bond position has not been introduced to the end to obtain conventional polybutene with a vinylidene content of 3-40%. Isobutylene. In the preparation of polybutene, the n-butene contained in the raw material may cause deterioration of product quality, productivity per unit of catalyst, and productivity per unit of raw material, but the higher isobutylene content in the raw material makes the product quality, per unit The productivity of the catalyst and the productivity per unit of raw material are improved.

[0005] In order to produce highly reactive polyisobutene with a high terminal vinylidene content and reduce the fluorine content from the catalyst in the product, it is particularly necessary to use high-quality isobutene raw materials from which n-butene has been removed. Even for the production of conventional polyisobutene, it is preferable to use a high-quality isobutene raw material from which n-butene is removed to reduce the chlorine content in the product and increase the productivity per unit of raw material or unit of catalyst. It is known that there are various types of 1-T that remove the most adverse effects on the quality of polybutene from n-butene.

Ene method. For example, U.S. Patent No. 5,674,955 discloses a method for producing polybutene from a raw material containing at least 5 wt% of 1-butene. -The butene content is reduced by at least 20wt%, and then a halogen compound is used as a catalyst for the polymerization step to produce polybutene with high vinylidene content and low halogen content. However, in this method, the isomerized 2-butene may still cause degradation of catalytic activity and catalyst durability. U.S. Patent No. 6207115 describes a method for producing propylene, which includes the selective hydrogenation of diene billets (such as butadiene) using an olefin billet conversion unit (0CU) and simultaneous isomerization of 1-butene to 2-Butene, polymerize polybutene, and then replace 2-butene and ethylene with propylene. However, this method also includes the production of polybutene in the presence of large amounts of 2-butene. This results in low durability of the catalyst.

[0006] The C4 oil produced by the contact degradation of medium-quality oil in the petroleum refining process and the C4 residue produced by the pyrolysis of naphtha contain 20-50wt% of 1-butene or 2-butene. The use of C4 olefin blanks in polybutene production may result in high halogen content and low vinylidene content in the polybutene product. In addition, the high content of n-butene such as 1-T ene present in the C4 olefin billet (ie, the raw material) may cause degradation of catalytic activity, polybutene quality, or productivity per unit of raw material. As a solution to this problem, high-purity isobutylene can be used. There are several methods for producing (separating) isobutene from C4 mixtures: (1) tert-butanol (TBA) dehydration method that combines hydration and dehydration reactions; (2) including the use of an acid catalyst to add methanol to isobutylene and then Methyl tert-butyl bromide (MTBE) cracking method that cracks into isobutene; and (3) isobutane dehydrogenation method. However, all these methods are expensive to produce (separate) isobutylene, leading to an increase in the cost of polybutene.

Summary of the invention

[0007] An object of the present invention is to provide a method for preparing polybutene, the method can economically prepare high-quality high-reactivity polybutene under a high-durability catalyst, the polybutene has a low content of Halogens such as fluorine, etc. and high terminal vinylidene groups.

[0008] Another object of the present invention is to provide a method for preparing polybutene with good productivity per unit of raw material or catalyst.

[0009] In order to achieve the object of the present invention, a method for preparing polybutene is provided, the method comprising: selecting the diene billet in the C4 billet component produced by the refinery or naphtha cracking center involved in cracking crude oil Hydrogenation reaction, while carrying out the isomerization reaction of converting 1-butene to 2-butene, and then separating the isobutene raw material through separation; and polymerizing the isobutylene raw material obtained through separation.

[0010] Effects of the invention

[0011] Advantageously, compared to the method of using the C4 billet raw material produced by the refinery or naphtha cracking center (NCC) involved in cracking crude oil, there is no after the simple process of isomerizing 1-butene to 2-butene. In any case of separate treatment or no use of raw materials, the preparation method of polybutene according to the present invention can economically produce high-quality and highly reactive polybutene under a high-durability catalyst, which has a low content of halogens such as Fluorine and high terminal vinylidene content.

[0012] Best Mode for Invention

[0013] Hereinafter, the present invention will be described in more detail.

[0014] The method for preparing polybutene includes: performing selective hydrogenation on the diene billet in the C4 billet component produced by the refinery or naphtha cracking center involved in cracking crude oil, while simultaneously converting 1-butene into The isomerization reaction of 2-butene, and then the isobutene raw material is separated through separation; and the isobutylene raw material obtained through separation is polymerized.

[0015] The hydrogenation reaction of the diene billet is the formation of n-butene (1-butene and 2-Butene) mixture reaction. Conversion of 1-butene to 2-butene

The isomerization reaction is a hydroisomerization reaction of converting 1-butene produced by the conversion of diene billets and 1-butene included in the C4 billet components into 2-τ ene. The hydrogenation reaction of the diene billet and the isomerization reaction of the conversion of 1-butene to 2-butene are carried out by supplying hydrogen to the C4 billet component in the presence of a metal catalyst. Metal catalysts that can be used in hydrogenation and hydroisomerization reactions may include Group 10 metals such as Ni, Pd, Pt, and the like. The metal catalyst can be supported on a supporting material. The amount of hydrogen used depends on the content of the diene billet in the C4 billet component. Preferably, the amount of hydrogen used is greater than the theoretical stoichiometric amount required for the conversion of the diene billet to n-butene, preferably slightly greater than the theoretical stoichiometric amount, such as, for example, for the diene billet, 1 -1. 2 equivalents, preferably 1-1. 1 equivalent. At this point, when the amount of hydrogen used is too much, the diene billet is poorly converted to n-butane. The temperature of the hydrogenation reaction and the hydroisomerization reaction is usually 20-200°C, preferably 50-150°C, and more preferably 60-150°The pressure of the Co hydrogenation reaction and the hydroisomerization reaction is usually 0. 1-5MPa, preferably 0.5-4MPa, more preferably 0.5-3MPa_oThe conditions for the hydrogenation reaction and the hydroisomerization reaction are disclosed in detail in U.S. Patent No. 6,207,115, and are incorporated herein by reference.

[0016] After the hydrogenation reaction and the hydroisomerization reaction of the C4 billet components, a separation step is performed to separate the isobutene raw material used in the polymerization of polybutene. Separating is a method of using a boiling temperature difference to separate a mixture of different liquids with a separate tower. The isobutene raw materials obtained (ie separated) by fractionation include isobutene as the main component and traces of 1-butene and 2-butene. The isobutene raw material loses most of the n-butene (ie 1-butene, etc.), and therefore contains relatively high purity isobutene. The separation conditions for obtaining isobutylene raw materials may include the number of separation columns in the separation tower, operating temperature, operating pressure, and so on. The range of the number of fractional columns in the distillation tower for obtaining isobutylene raw materials suitable for the present invention is 20-150, preferably 50-130, more preferably 70-130. When the number of fractional columns in the separation tower is less than 20, The separation efficiency of raw materials may become deteriorated, reducing the purity of isobutylene (IB). When the number of split columns in the split tower is greater than 150, unnecessary equipment costs are incurred. The partial temperature is 0-100°C, preferably 10-80°C, and more preferably 20-80°C. When the partial temperature is lower than 0°C, the cost of the vacuum equipment and its accessories increases. When the partial temperature is higher than 100°C, it causes unnecessary energy consumption and increases in equipment costs for maintaining high pressure. When the temperature is higher than the defined range, it is impossible to obtain the required high-quality and highly reactive polyisobutylene. Regret pressure It is 0-30 atm (atmospheric pressure), preferably 2-15 atm, more preferably 3-10 atm, and still more preferably 5-10 atm. A partial pressure approaching zero means vacuum steaming. When the partial pressure exceeds 30 atm, the boiling point of the mixture increases, which requires more energy consumption and increases the cost of peripheral equipment. In addition, when the partial pressure exceeds the defined range, high-quality and highly reactive polyisobutylene may not be obtained. Using the isobutylene raw material obtained through separation to synthesize polybutene by polymerization, it is possible to produce high-quality (ie high vinylidene content and low halogen content) and high production efficiency comparable to those synthesized from high-purity isobutylene polybutene. Polybutene. Exemplary compositions of the isobutylene feedstock are listed in Table 1 below. The isobutylene raw material is separated under limited conditions such as 105 sub-columns in the sub-column, 50°C/60°C (top/bottom) steam temperature, 6 atm steam pressure, and used together In the present invention.

[0017] [Table 1]

[0018]

<td>Element</td><td>Isobutylene</td><td>N-butane</td><td>1- Butene</td><td>Cis-2-butene</td><td>Trans-2-butene</td><td>Isobutane</td>

<td>Content (wt%)</td><td>45. 2</td><td>0. 4</td><td>1. 9</td><td>0. 1</td><td>0. 9</td><td>51. 3</td>

[0019] Table 2 below lists the composition of the C4 billet component produced by the naphtha cracking center to remove the diene billet and the C4 residue from the hydrogenation reaction. Table 2 shows that the composition of the C4 residue contains a large amount of n-butene components (1-butene, C (cis)- or T (trans_-2-butene, etc.), and therefore it is impossible to use it with high High vinylidene content and low halogen content

Preparation of reactive polyisobutylene.

[0020] [table2]

[0021]

<td>Element</td><td>Isobutylene</td><td>N-butane</td><td>1- Butene</td><td>Cis-2-butene</td><td>Trans-2-butene</td><td>Isobutane</td>

<td>Content (wt%)</td><td>49. 5</td><td>10. 9</td><td>24.8</td><td>4. 2</td><td>09. 3</td><td>2. 9</td>

[0022] The following Table 3 lists the selective hydrogenation reaction using the olefin conversion unit (OCU) to remove diene and ethane and isomerize 1-butene to 2-butene (simply by The composition of the isobutene raw material produced by isomerization.

[0023] [table3]

[0024]

<td>Element</td><td>Isobutylene</td><td>N-butane</td><td>1- Butene</td><td>Cis-2-butene</td><td>Trans-2-butene</td><td>Isobutane</td>

<td>Content (wt%)</td><td>44. 9</td><td>10. 9</td><td>1. 7</td><td>14.2</td><td>23. 4</td><td>4. 9</td>

[0025] Subsequently, the isobutylene produced (isolated) as above is polymerized according to a general method to form polybutene. The method of producing polybutene from isobutene raw materials can be classified into the method of using aluminum trichloride (A1C1J as a catalyst to produce conventional polyisobutene) and the method of using boron trifluoride (BF₃) As a catalyst and co-catalyst to produce high-reactivity polyisobutylene and medium-reactivity vinylidene polyisobutylene. The method of using aluminum trichloride (A1C1J as a catalyst) to produce conventional polyisobutylene is well known. Therefore, the method of using aluminum trifluoride (BF₃The method of producing highly reactive polyisobutylene in the presence of) is briefly described.

[0026] In the preparation of high-reactivity polyisobutylene, the co-catalyst (ie alcohol, distillate, etc.) and boron trifluoride (BF₃) Directly added to the reactor, or produced in the form of a complex in a separate tank, and then put into the reactor. The alcohol compound used as the co-catalyst may be a primary, secondary or tertiary alcohol having 1 to 4 carbon atoms, such as, for example, methanol, ethanol, isopropanol, n-propanol, isobutanol, tert-butanol, and the like. The co-catalyst may be a primary, secondary or tertiary dimethoate having 2 to 8 carbon atoms, such as, for example, dimethyl dimethoate, diethyl dimethoate, diisopropyl dimethoate, methylpropyl dioxygen, methyl isopropylate Propyl phosphate, methyl ethyl phosphate, methyl butyl phosphate, methyl tert-butyl phosphate, ethyl propyl phosphate, ethyl isopropyl phosphate, ethyl butyl phosphate, ethyl isobutyl phosphate, ethyl Tert-Butyl Dioxide and so on. The co-catalyst can be used alone or in combination with at least one of other co-catalysts. When forming a complex of a co-catalyst and boron trifluoride, the co-catalyst used alone or in combination with at least one of the other co-catalysts is added to the tank, and then boron trifluoride gas is added to easily form the complex. Compound. At this point, the reaction to form a complex of boron trifluoride and alcohol is an exothermic reaction. Therefore, the heat of reaction needs to be eliminated to reduce the risk of catalyst decomposition and explosion. Specifically, in order to completely eliminate the heat of reaction to maintain the stability of the catalyst, the complexation reaction is carried out at a low temperature, preferably 10°C or less, more preferably 0°C or less, and most preferably -40°C to- 10°C. Control the use of catalysts as needed 0 Parts by weight. The amount, so that the content of boron trifluoride in the catalyst component is 0.05-1. 0 parts by weight based on 100 parts by weight of isobutylene in the isobutylene raw material. When the amount of boron trifluoride used is greater than 1.0 part by weight, it may result in the formation of a product with an excessively low molecular weight and the deterioration of productivity per unit of catalyst, as well as poor economic efficiency caused thereby. When the amount of boron trifluoride used is less than 0.05 parts by weight, the yield of polybutene deteriorates, which is undesirable in terms of economy.

[0027] For highly reactive polyisobutene, the polymerization (reaction) temperature is usually -30°C to 20°C, and the polymerization (reaction) pressure is determined to keep the isobutene raw material in a liquid state at the corresponding reaction temperature, that is, usually 3kg/ cm²Or higher. Generally, the conversion of isobutylene is at least 70%, more preferably about 80-95%. In the present invention, the above conversion rate is achieved

The required residence time is generally 5-100 minutes. In terms of economics, it is not desirable to keep the retention time outside the defined range. Once the polymerization of polybutene is completed, subsequent steps such as neutralization commonly used in the related art are carried out to complete the preparation of highly reactive polyisobutene. The number average molecular weight (Mn) of the highly reactive polyisobutylene prepared according to the present invention is 300-5000, the vinylidene content is at least 80%, and the isobutylene conversion rate is at least 85%.

[0028] The preparation method of polybutene according to the present invention makes high-efficiency polymerization possible. This polymerization can not only produce vinylidene (ie, the double bond at the end of the polybutene among the total double bonds present in polybutene ( Vinylidene)) Highly reactive polyisobutene with a content of at least 70%, and a moderately reactive vinylidene polyisobutene with a vinylidene content of about 40-70% and/or a vinylidene content of 3-40 % Of conventional polyisobutylene. In the preparation of polybutenes, especially highly reactive polybutenes with a vinylidene content of at least 80% and an isobutylene conversion rate of at least 85%, when using typical boron trifluoride complex catalysts and general separation methods When separating high-purity isobutylene, the cost of raw materials is greatly increased, so that uncompetitive products are obtained. However, the use of the isobutene raw material separated according to the present invention in the preparation of polybutene can economically produce high-quality polybutene with low fluorine content and high vinylidene content under a highly durable catalyst.

[0029] The C4 oil produced by the contact degradation of medium-quality oil in the petroleum refining process and the C4 residue produced by the pyrolysis of naphtha contain 20-40wt%, especially 20-35wt% of n-butene (ie 1- Butene, etc.), the productivity and quality of polybutene products may be degraded (that is, have low vinylidene content and high halogen content). However, the polybutene production method according to the present invention uses raw materials from which the n-butene component that may deteriorate product quality and productivity is removed, thereby solving the above-mentioned problems. More advantageously, the highly reactive polybutene with high vinylidene content prepared according to the present invention not only shows a higher content of active ingredients with cleaning functions in the preparation of lubricants, fuel cleaners, etc., but also Low halogen content, which prevents corrosion of reactants that may occur in the preparation of additives for fuel cleaners or lubricants.

[0030] Hereinafter, the present invention will be described in further detail with reference to the following examples and comparative examples, which are for understanding the present invention and are not intended to limit the scope of the present invention.

[0031] [Example 1-4] Preparation of highly reactive polybutene

[0032] Selective hydrogenation of the diene billet (ie butadiene) from the C4 billet raw material produced by the refinery involved in cracking crude oil or the naphtha cracking center (NCC), while isomerizing 1-butene It is 2-butene. Then, carry out the splitting process (105 splitting columns in the splitting tower, 50°C/60°C steaming temperature (top/bottom), 6atm steaming pressure) to obtain a steam pressure as shown in Table 1. Shows the composition of the isobutylene raw material. The isobutylene raw material with the composition of Table 1 is continuously supplied to a stainless steel pressure reactor equipped with a cooling device, and then the polymerization temperature (reaction temperature), catalyst (BF3) and co-catalyst (such as ethanol, ethanol, or Diisopropylate (IPE)) was polymerized to produce polybutene (Examples 1-4). At this point, the pressure of the reactor is maintained at 3kg/cm²Or higher to keep the isobutylene feedstock in a liquid state. The average residence time is 30 minutes. After 180 minutes, the polymer liquid was collected from the reactor outlet directly into a container containing a 5wt% caustic soda solution, mixed with about 3 times the volume of hexane, and then washed with water three times to remove unreacted raw materials and solvents. Finally, a 30-minute stripping process is performed at 220°C and 5 mmHg to remove the remaining components with low boiling temperature, so as to obtain the target product polybutene. The molecular weight (number average molecular weight, Mn) and molecular weight distribution (MWD) of the final product were measured using gel permeation chromatography (GPC). In addition, C13-NMR was used to analyze the vinylidene content (%), and the ion selective electrode (ISE) method was used to determine the fluorine content (ppm). The measurement results are listed in Table 4. In Table 4, the "IB content after reaction (%)" and "IB conversion rate (%)" are determined by comparing the isobutylene (IB) content before and after the reaction to analyze the reaction participation level of isobutylene (IB).

[0033] [Comparative Examples 1 and 2] Preparation of highly reactive polybutene

[0034] The C4 billet raw material produced by the Naphtha Cracking Center (NCC) was removed butadiene to obtain the group as shown in Table 2.

The resulting C4 residue-1 (raffinate-1) is then used as a raw material for isobutylene. The isobutylene raw material with the composition shown in Table 2 was continuously supplied to a stainless steel pressure reactor equipped with a cooling device, and then the polymerization temperature (reaction temperature), catalyst (BFJ, and co-catalyst (such as ethanol, ethanol) as listed in Table 4) were used. , Or diisopropylate (IPE)) was polymerized to produce polybutene (Comparative Examples 1 and 2). Other conditions were the same as those described in Examples 1-4. The same manner as described in Examples 1-4 was adopted. Analyze the molecular weight (number average molecular weight Mn), molecular weight distribution (MWD), vinylidene content (%), fluorine content (ppm), IB content (%) after the reaction, IB conversion rate and catalyst of the polybutene thus obtained (The durability of PIB/BFJ. The measurement results are listed in Table 4.

[0035] [Comparative Examples 3 and 4] Preparation of Highly Reactive Polybutene

[0036] The diene billet made from the C4 billet raw material (ie, butadiene) produced by the oil refining equipment or the naphtha cracking center (NCC) involved in cracking crude oil is selectively hydrogenated, while selectively hydrogenating 1-butene Isomerized to 2-butene to obtain an isobutene raw material having the composition shown in Table 3. The isobutylene raw material with the composition shown in Table 3 is continuously supplied to a stainless steel pressure reactor equipped with a cooling device, and then the polymerization temperature (reaction temperature) and catalyst (BF) listed in Table 4 are used.₃) And a co-catalyst (such as ethanol, ethanol, or diisopropylate (IPE)) to polymerize to produce polybutene (Comparative Examples 3 and 4). Other conditions are the same as described in Examples 1-4. The molecular weight (number average molecular weight Mn), molecular weight distribution (MWD), vinylidene content (%), fluorine content (ppm), and reaction of the polybutene thus obtained were analyzed in the same manner as described in Examples 1-4. After IB content (%), IB conversion rate and durability of the catalyst (PIB/BFJ). The measurement results are listed in Table 4.

[0037] [table4]

[0038]

<td></td><td>Example 1</td><td>Example 2</td><td>Example 3</td><td>Example 4</td><td>Comparative example 1</td><td>Comparative example 2</td><td>Comparative example 3</td><td>Comparative example 4</td>

<td>Methanol</td><td>1.70</td><td></td><td>1.0</td><td></td><td></td><td></td><td>1.7</td><td></td>

<td>Ethanol</td><td></td><td>1.65</td><td></td><td>1.0</td><td>1*65</td><td>2.0</td><td></td><td>1.65</td>

<td>1PE</td><td></td><td></td><td>0.6</td><td>0.55</td><td></td><td></td><td></td><td></td>

<td>Co-catalyst/'BF3 molar ratio</td><td>1.7</td><td>1.65</td><td>1.60</td><td>1.55</td><td>1*65</td><td>2.0</td><td>1 7</td><td>I 05</td>

<td>IB content after reaction (%)</td><td>7：.5</td><td>8,6</td><td>9.0</td><td>84</td><td>14.6</td><td>143</td><td>8.2</td><td>8 4</td>

<td>IB conversion rate (%)</td><td>93</td><td>92</td><td>91</td><td>92</td><td>83</td><td>83</td><td>92</td><td>92</td>

<td>Reaction temperature (°C)</td><td>-25</td><td>-25</td><td>-18</td><td>-18</td><td>-25</td><td>male;;</td><td></td><td>Λ</td>

<td>Catalyst durability (P1B/BF?)</td><td>634</td><td>61；0</td><td>603</td><td></td><td>412</td><td>.162</td><td>24()</td><td>2(&gt;(</td>

<td>Vinylidene (%)</td><td>8&amp;3</td><td>89.3</td><td>90.5</td><td>90 3</td><td>80.2</td><td>85.0</td><td>86 0</td><td>87.8</td>

<td>F(ppm)</td><td>6</td><td>4</td><td>3</td><td>4</td><td>41</td><td>31</td><td>5</td><td>4</td>

<td>Mn(MWD)</td><td>1830(1.85)</td><td>2350(1.90)</td><td>1060(1.34)</td><td>1370(1.47)</td><td>2250(1.88)</td><td>1270(1.55)</td><td>1980(1.79)</td><td>2410(1.88)</td>

[0039] In Table 4, "co-catalyst/BF3" represents the ratio of the total number of moles of the promoter to the number of moles of BF3. Depend on

It can be seen from Table 4 that the vinylidene content of the polybutene prepared according to Examples 1-4 of the present invention is at least 88% (the higher the better) and the F content is 10 ppm or lower (the lower the better), which Meet high quality and high reactivity standards. In contrast, when using the C4 residue-1 raw material in Comparative Examples 1 and 2, although the raw material cost is low, the amount of catalyst and cocatalyst used is too large, and the product yield is low, resulting in increased product cost and polymerization. The properties of butene products deteriorate. In addition, when the isobutylene raw material obtained by simple isomerization as in Comparative Examples 3 and 4 is used, although it is possible to produce good quality polybutene to a certain extent, the extremely low durability of the catalyst will disadvantageously lead to low productivity.