WO1999007753A1 - Process for preparing halogen-free, reactive polyisobutylene - Google Patents

Abstract

A process is disclosed for preparing halogen-free, reactive polyisobutylene with a content of terminal double bonds of more than 50 % by moles and an average molecular weight Mn of 500 to 5000 daltons by cationic polymerisation of isobutylene or isobutylene-containing hydrocarbon mixtures in the liquid phase. Polymerisation is carried out at a temperature of between -40 and +10 DEG C in the presence of a molybdate or wolframate heteropolyacid.

Description

Process for the production of halogen-free, reactive polyisobutene

description

The present invention relates to a process for the preparation of free of charge, reactive polyisobutene with a content of terminal double bonds of more than 50 mol% and an average molecular weight M _n of 500 to 5000 daltons by the cationic polymerization of isobutene or isobutene-containing hydrocarbon mixtures in liquid Phase in the presence of molybdato heteropolyacids.

Isobutene polymerization forms an inseparable mixture of polyisobutenes with different positions of the double bond in the individual polyisobutenes. Polyisobutenes of the formula I.

in which n indicates the degree of polymerization, which in turn results from the average molecular weight M _{n of} the polyisobutene produced, contain terminal CC double bonds of the vinylidene type, which in this application are also referred to as α-olefinic double bonds due to their position in the polyisobutene molecule . Accordingly, the double bonds in polyisobutenes of the formula II

referred to as ß-olefinic. If no special measures are taken in the polymerization of isobutene, a statistical mixture of polyisobutenes with α-olefinic, ie terminal, β-olefinic and double bonds located further inside the polyisobutene molecule is formed. The content of terminal double bonds in a polyisobutene product produced by a specific production process and the content of β-olefinic double bonds are stated in mol%. Polyisobutenes with molecular weights of up to 100,000 daltons are known. These olefins, which are described, for example, in H. Güterbock, Polyisobutylenes and Copolymers, pp. 77-104, Springer-Verlag, Berlin, 1959, 5 are usually carried out by Lewis acid-catalyzed isobutene polymerization, aluminum Lewis, alkyl being the Lewis acids - Aluminum chloride or boron trifluoride can be used. However, the polymers obtained in this way have a relatively low content of terminal CC double bonds 0 of the vinylidene type with less than 10 mol%.

In contrast, reactive polyisobutene (PIB) with molecular weights of usually 500 to 5000 daltons has a high content of terminal vinylidene groups, preferably of more than 15 50 mol%. These reactive polyisobutenes as Zwischenpro ^¬-products for the production of lubricant and Kraf tstoff -Additi - ven as they are described for example in DE-A 27 02 604 is used. To produce these additives, polyisobutene is first reacted with maleic anhydride. In this case, preferably 20 to react the terminal double bonds of the vinylidene type, whereas double bonds that are located further inside of the macro ^¬ molecule, depending on the position in the molecule to a lesser extent or even not respond. The polyisobutene-maleic anhydride adducts formed are then converted into the corresponding additives by reaction with 25 specific amines. A high proportion of terminal double bonds is therefore absolutely necessary for polyisobutenes, which are used as starting materials for the additives mentioned above. The same applies to the production of the 30 polyisobutenamines according to EP-A 244 616, which are also used as fuel, and which are produced by hydroformylation of the reactive polyisobutene and subsequent reductive amination of the polyisobutenaldehyde obtained in the process. Polyisobutene with a high content of terminal double bonds is also preferably used here, but ß-olefinic polyisobutenes are also hydroforylated to the desired product in the hydroformylation with cobalt catalysts owing to their double bond isomerization activity.

The production of reactive polyisobutene by the homogeneous catalytic lytic polymerization of isobutene is already known. For example, according to DE-A 27 02 604, a polyisobutene product which has a content of terminal double bonds of up to 88% is obtained by reacting isobutene in the presence of boron trifluoride. EP-A 145 235 teaches the polymerization of 45 isobutene in the presence of a complex of boron trifluoride and a primary alcohol in a temperature range from -100 ° C to + 50 ° C, products with similarly high vinylidene double bond contents be preserved. With complexes of boron trifluoride and secondary alcohols as catalysts, highly reactive polyisobutene can also be prepared according to US Pat. No. 5,286,823.

A disadvantage of these homogeneously catalyzed processes is that the Lewis acid catalysts used are corrosive and there is a risk that halogenated, polymeric by-products are formed in addition to the desired reactive polyisobutene, which are practically inseparable from the PIB and adversely affect the product and processing properties of the PIB. The separation of the homogeneous catalyst in these methods is usually carried out by quenching with a nucleophile, whereby the catalyst is destroyed, and subsequent separation of the PIB Extrak ^¬ tive from the quench mixture. These additional workup steps represent a further disadvantage of the homogeneously catalyzed process for the production of PIB.

WO 94/28036 relates inter alia to the production of polyisobutene using heterogeneous Lewis acid-like catalysts. As such, insoluble salts of elements from III., IV., V. and VI. Subgroup of the periodic table of the elements used, preferably their halides, sulfates, perchlorates, trifluoromethanesulfonates, nitrates and fluorosulfonates. In the examples of this application, only the halogenice of these elements are used as catalysts for the isobutene polymerization. An indication of the properties of the polyisobutene obtained in these examples is given neither with regard to the molecular weight nor with regard to the content of terminal double bonds. To terminate the polymerization, the reaction medium is mixed with methanoic ammonia solution, as a result of which the catalysts in question are destroyed or at least inactivated to a considerable extent.

The production of PIB using heterogeneous catalysts is also known. US Pat. No. 4,288,649 describes a process for the preparation of polyisobutene having an average molecular weight of> 1250 daltons by the polymerization of isobutene-containing C ₄ -hydrocarbon mixtures over halogenated aluminum oxide catalysts. These catalysts are produced by treating the aluminum oxide with a halogenating agent, preferably with a chlorinating agent, in particular with carbon tetrachloride, at elevated temperature. This process has the disadvantage that part of the chlorine is transferred from the catalyst to the polymer being formed. For example, the polymerization of a mixture of n-butane, isobutane and isobutene on a chlorinated aluminum oxide prepared in this way Catalyst after 2 hours of reaction to a polyisobutene product with a chlorine content of 46 ppm.

US Pat. No. 5,326,920 relates to a process for isobutene polymerization, 5 in which an oxidic support material, preferably silicon dioxide, which has been activated with a metal chloride, preferably an aluminum chloride, attached to it, is used as the heterogeneous catalyst. According to this document, an Si0 -AlCl catalyst is particularly preferably used in which 0 A1C1 groups are anchored to the Si0 ₂ support via oxygen bridges. A disadvantage of this process is that the polyisobutene products obtained have an extremely broad molecular weight distribution D 8-14, their content of terminal double bonds ^¬ is low and its chlorine content in the ppm range. 5 In addition, this process requires the presence of promoters such as water, alcohols, alkyl halides or hydrogen chloride in order to achieve sufficient catalyst activity for industrial operation. Similar catalyst systems are described in WO 95/26815, WO 95/26816, WO 95/26814 and WO 95/26818 0 for isobutene polymerization.

According to JP-A 139 429/1981, heterogeneous catalysts containing zirconium dioxide and molybdenum oxide are used for the production of isobutene oligomers having a molecular weight of less than 300 daltons 5. Aluminum fluoride can also be added to these catalysts to increase their activity. For example, according to this document, when converting an isobutene-containing C _{4 cut} (composition: 46% isobutene, 28% 1-butene, 8% 2-butenes, 12% n-butane, 5% isobutane, 1% 1, 3 -Butadiene) at

30 120 ° C. on a M0O ₃ -Zr0 ₂ catalyst, a molybdenum content of 13% by weight, calculated as Mo0 ₃ , obtained a mixture of isobutene oligomers which were 29%, 49% and 19% of di- , Tri or tetraisobutene.

35 NL-A 7 002 055 relates to a process for the preparation of isobutene oligomers in the gas phase with a tin oxide / molybdenum oxide on a silicon dioxide catalyst. This gives a mixture of dimers, trimers and tetramers of isobutene.

40 EP-A 535 516 relates to a catalyst for the production of ethylene polymers which contains chromium trioxide on a special SiO 2 carrier material. A teaching on the production of reactive, low molecular weight polyisobutene is not given in this document.

45 GB-A 1 115 521 describes, inter alia, the polymerization of isobutene on a Na-X zeolite loaded with a platinum compound. This essentially produces dimers and trimers of isobutene in addition to smaller amounts of tetramers and higher polymers. No information is given about the molecular weight of the higher polymers produced in this way and their content of terminal double bonds.

DE-A 19528942 relates to a process for the production of low molecular weight, reactive and halogen-free polyisobutene, in which a support material doped with various promoters made from an oxygen-containing compound of zirconium is used as the catalyst.

CA 738019 describes a process for isobutene polymerization, in which supported heteropolyacid catalysts are brought into contact with isobutene at 20-200 ° C. and catalyst loads of 1 to 40 h ^-1 . Specifically, a process for the production of triisobutene by isobutene is brought into contact - Polymerization is described at 40 to 140 ° C., in which heteropolyacids applied as carrier materials on essentially alkali-free gels are used as catalysts The formation of the isobutene trimers desired according to the teaching of this patent can be promoted by low reaction temperatures, at higher temperatures The isobutene polymerization is carried out exclusively in the gas phase and the isobutene trimers obtained are mainly composed of 2, 2, 6, 6-tetramethyl-4-methyleneheptane and 2, 2, 4, 6, 6-penta - methyl - 3-heptene The products obtained by this process have only a low molecular weight (dimers 112, trimers 168, tetramers 224) and do not have the alpha or beta olefin structure according to formulas I and II. A teaching on the production of reactive, higher molecular weight polyisobutene is not to be found in this patent.

JP-A 14538/1982 describes a process for the preparation of isobutene oligomers by selective isobutene oligomerization in the presence of n-butene on dehydrated heteropolyacids and / or heteropolyacid salts at temperatures <120 ° C. Isobutene oligomers are mainly understood to mean isobutene dimers with small amounts of isobutene trimers and the isobutene polymerization is carried out exclusively under conditions in which the starting materials are in the gas phase. There is no teaching in the publication of the production of reactive, higher molecular weight polyisobutene with terminal double bonds in the present case. Furthermore, JP-A 102825/1982 discloses processes for the preparation of isobutylene di- and tπmeren on tungsten heteropolyacids. Although these heteropolyacids are calcined at 250-400 ° C., de oligomerization is carried out at temperatures from 50 to 5150 ° C., in particular at 100 ° C. 140 ° C., ie always in the gas phase. A lowering of the temperature is referred to as WANTED Unwanted, since a reduction in the yield of the Select Required di- and Tr mers at temperatures below 50 ° C was obser ^¬ tet. Accordingly, no teaching is given for the production of reactive, high molecular weight polyisobutene at low temperature in the liquid phase.

gegenüber Wolframatophosphorsauren deut- iicn geringer ist. Auch hier wird weder bezuglich des Produktes, der Reaktionsbedingungen und der für die Herstellung des reak- 5 tiven Polyisobutens eines bestimmten Molekulargewichts erforderlichen speziellen Katalysatoren eine Lehre gegeben.Finally, Cai-T an Xi et. al. m Cuihua Xuebao (1985), 6 (4), 370 the oligomerization of l-butene on heteropolyacids and 5 -salts. The oil is gomeπsation durengefαhr also under conditions in which I butene is as a gas phase before ^¬. The authors note that at relatively low temperatures en dimers are formed as the main product and that the proportion of tetrameric and non-polymeric polymers can be increased to 120 ° C. by increasing the temperature. It is also observed that the activity of 12 -molyddatopnosphoric acid and 12

compared to tungsten phosphoric acids is significantly lower. Here too, no teaching is given with regard to the product, the reaction conditions and the special catalysts required for the preparation of the reactive polyisobutene of a certain molecular weight.

The present invention was also based on the problem, a process for the preparation of halogen-free, reactive polyisobutene with a content of terminal double ends of less than 50 mol%, in particular a content of terminal non-β-olefinic double bonds of more than 80 mol -% and to find an average molecular weight of 500 to 5000 daltons with the aid of a heterogeneous catalyst, which is not the aforementioned

Has 35 parts and is technically easy to carry out.

This object was achieved in accordance with the invention with a process for the preparation of halogen-free, reactive polyisobutene with a content of terminal double bonds of more than

40 50 mol% and an average molecular weight M _n of 500 to 5000 daltons by cationic polymerization of isobutene or hydrocarbon mixtures containing isobutene m liquid phase, in which the polymerization at a temperature of -40 to + 10 ° C in the presence of a dehydrated molybdate - or wolfra-

45 mato-heteropolyacid performs. The heteropolyacids to be used according to the invention contain tungsten or preferably molybdenum as the essential element, partial substitution by vanadium being possible. When using vanadium, the preferred atomic ratios are V: Mo 1: 6 to 1: 12. Examples of the central atoms are phosphorus, silicon, arsenic, germanium, boron, titanium, cerium, thorium, manganese, nickel, tellurium, iodine, cobalt, Chromium, iron, gallium, vanadium, piatm, beryllium and zinc. Phosphorus and silicon are preferred. The preferred ratio of molybdenum or tungsten atoms to the respective central atom is 2.5: 1 to 12: 1, preferably 11: 1 to 12: 1.

The following compounds may be mentioned as examples of heteropolyacids containing molybdenum:

Dodeca olybdatophosphoric acid (H ₃ PMo ₁ θ ₄ o * n H0),

Dodecamolyodatosilicic acid (H <ιSιMθι ₂ θ ₄ o * n H ₂ 0),

Doαecamolybdatocer (IV) acidic (H _g CeMo ₁₂ 0d ₂ * n H ₂ 0),

Dodecamolybdatoarsen (V) acidic (HτAs θι ₂ 0 ₄₂ * n H ₂ 0), hexamolybdatochrome (III) acidic (H ₃ CrMθ ₆ θ ₄ H ₆ * n H ₂ 0),

Hexamolybdatonickel (II) acidic (H ₄ NιMo ₆ 0 ₂₄ H ₆ * 5 H ₂ 0),

Hexamolybdate θ3θdsaure (H ₅ JMθ ₆ θ ₂₄ * n H0),

Octadecamolybdatodiphosphoric acid (H ₆ PMθι ₈ θ ₆₂ * 11 H0),

Octadecamolybdatodιarsen (V) acid (H ₆ s ₂ MθιaOs ₂ * 25 H ₂ 0), Nonamoiybdatomangan (IV) acid (HgMnMogO ^ * n H ₂ 0),

Undecamolybdatovanadatophosphoric acid (H ₄ PM0 ₁₁ VO ₄₀ * n H ₂ 0),

Decamolybdatod vanadatophosphoric acid (H ₅ PM0 ₁₀ V ₂ O ₄₀ * n. H ₂ 0),

Hexamolydatohexatungstopnospnorsaure (H ₃ PMθ ₆ Wςθ ₄ o * n H ₂ 0).

Mixtures of heteropolyacids can of course also be used. Dodecamolybdatophosphoric acid and dodecamolybdatosilicic acid are preferably used.

The heteropolyacids are known compounds and can be prepared using known methods, for example using the methods of Brauer (editor): Handbuch der Praparativen Anorganischen Chemie, Volume III, Enke, Stuttgart, 1981 or the methods of Top. Curr. Chem. 76, 1 (1978). Preparation methods which do not require the use of organic solvents and are instead carried out in aqueous solution are particularly preferred.

The heteropolyacids thus produced are generally in hydrated form and are freed of the co-ordinatively bound water contained therein before they are used. The dehydration can advantageously be thermal, for example by the Makromol process. Chem. 190, 929 (1989). Another possibility for dehydrating the heteropolyacids, depending on the heteropolyacid used, is to dissolve the heteropolyacid in an organic solvent, for example in a dialkyl ether or alcohol, to displace the water with the organic solvent from its coordinative bond with the heteropolyacid and to azeotropically with it Distilled off solvent.

Anhydrous heteropolyacids produced by these methods are generally subsequently calcined at temperatures of 250 to 500 ° C., preferably 280 to 400 ° C. Depending on the temperature and the selected pressure, the calcination is usually between one hour and 24 hours. The catalysts thus obtained can be used directly in the process according to the invention.

The heteropolyacid catalysts can also be used supported. For this purpose, the heteropolyacid is applied to a carrier material which is inert under the reaction conditions, such as activated carbon, silicon dioxide, titanium dioxide or zirconium dioxide, by methods known per se, for example by soaking the carrier material in question with a solution of the heteropolyacid in a solvent, preferably water, and then at temperatures of 100 to 250 ° C, preferably 130 to 250 ° C under reduced pressure until water is no longer detectable in the catalyst. Prepared by these methods, anhydrous heteropolyacids are subsequently at temperatures of 250 to 500 ° C preferably 280 to 400 ^C calcined C.

The catalysts to be used according to the invention are expediently shaped or comminuted to give shaped articles, such as tablets, spheres, cylinders, rings or spirals, or comminuted into chippings before being used, and are preferably used in this form in a fixed bed arrangement in the reactor, or they become powder marry and in this form, e.g. used as suspension catalysts.

The catalysts to be used according to the invention can be stored practically without restriction, especially with the exclusion of moisture. Catalysts which have become moist are advantageously dried at atmospheric pressure or under reduced pressure before they are used, at atmospheric pressure generally at temperatures above 150 ° C., preferably at 180 to 250 ° C., at reduced pressure even at lower temperatures. Both pure isobutene and isobutene-containing hydrocarbon mixtures, such as C ₄ raffinate or isobutane / isobutene mixtures from isobutane dehydrogenation, can be used as starting material in the process according to the invention. C ₄ raffinate is a mixture of carbon and 5 hydrogen mixtures which are removed from the C ₄ section of steam crackers or FCC crackers (FCC: Fluid Catalyzed.) By removing the 1,3-butadiene to a large extent, ie to a trace Cracking) have been obtained (see Weissermel, Arpe: Industrielle Organische Chemie, pp. 69, 10 102-103, 2nd edition, Verlag Chemie 1978).

The process according to the invention can be carried out discontinuously or continuously at temperatures of generally from -40 ° C. to + 10 ° C., preferably from -30 to + 10 ° C. and particularly preferably from -20 ° C.

15 to + 10 ° C, under atmospheric pressure or elevated pressure, in particular under the autogenous pressure of the reaction system, who ^¬ carried out so that the isobutene remains liquid. Conventional reactors, such as stirred reactors or loop reactors in the batch mode, or loop reactors,

20 cascades can be used in the continuous operation of the process. Likewise, tubular reactors or tubular reactor cascades operated in sump or trickle mode can advantageously be used in the continuous operation of the process according to the invention. The catalysts to be used according to the invention

In this case, preferably when using loop reactors or tubular reactors, it can be arranged in a fixed bed or suspended in the form of powder in the reaction medium. Typical catalyst loads are 10 kg isobutene / kg cat. * H to 0.1 kg / kg * h, preferably 7 to 0.2 kg / kg * h, especially before -

30 pulls 5 to 0.3 kg / kg * h. Depending on the embodiment, typical residence times are 0.05 to 30 h, preferably 0.1 to 20 h, particularly preferably 0.2 to 10 h.

The isobutene polymerization can be carried out in the presence or absence of preferably non-polar, halogen-free solvents, preferably hydrocarbons. When using isobutene-containing hydrocarbon mixtures as the starting material, the hydrocarbons additionally contained therein, in addition to the isobutene, act as solvents or diluents. Butanes, pentanes, hexanes, heptanes and octanes, which can be linear or branched, are preferred. Butanes, pentanes and hexanes are particularly preferred. Since the isobutene polymerization is exothermic, it can be advantageous to equip the reactors used with devices for internal or external cooling. 45 The desired average molecular weight M _{n of} the polyisobutene can be set by varying the reaction parameters, in particular by varying the temperature, residence time and catalyst load. 5

In the batch process, the average molecular weight M _n is generally adjusted by varying the amount of catalyst used, the reaction time and the reaction temperature. Depending on the amount of catalyst used, the reaction time is generally from 0.01 to

10 hours, preferably 0.1 to 8 hours. In the discontinuous embodiment of the process according to the invention, the catalyst is generally obtained in an amount of 0.1 to 50% by weight, preferably 0.5 to 20% by weight and particularly preferably 1 to 15 10% by weight to the weight of the isobutene contained in the starting material used. Advantageously - as are, depending on the catalyst employed and output - material, the optimum polymerization conditions for Her ^¬ position of polyisobutene having an average molecular desired - 20 weight M _n in preliminary determined. In the continuous operation of the process according to the invention, the average molecular weight M _{n is} adjusted accordingly, but instead of the amount of catalyst used, the reaction parameters of catalyst loading and residence time are varied. 25th

The isolation of the polyisobutene from the polymerization mixture generally has no special procedural features and, if a suspended catalyst is used after it has been separated off, for example by filtration, centrifugation or decanting, can be carried out by distillation, expediently initially volatile constituents of the polymerization mixture, such as Unreacted isobutene, hydrocarbons contained in the starting material or added as a solvent, are distilled off and then higher-boiling by-products, for example low-molecular weight isobutene oligomers, are separated off from the polyisobutene by distillation.

The process according to the invention enables the production of reactive, halogen-free polyisobutene of an average molecular weight

40 weight M _n of generally 500 to 5000 daltons and one

Content of terminal double bonds of more than 50 mol% in a particularly economical manner. Compared to the closest method of DE-A 19528942, the present method is characterized by further improved yields.

45 Examples

I. Preparation of the catalyst

The catalyst was made and used in the form of powder. The contents of the catalyst in Mo and P were determined by means of X-ray fluorescence analysis (Lit. R. Bock: Methods of Analytical Chemistry; Volume 2: Detection and Determination Methods Part 1, Verlag Chemie, Weinheim 1980).

Manufacturing:

125 g (NH ₄ ) ₆ Mo ₇ 0 ₂₄ * 4 H ₂ 0 are dissolved in 150 ml water at 40oC and 8 g H ₃ PO ₄ (76) are added. HN0 is added to this solution while stirring until a pH of 2 is reached. After evaporation, the solid is heated to 300 ° C. for 16 hours under a nitrogen atmosphere.

Analysis:

Mo: 61.0 g / 100 g P: 1.8 g / 100 g

II. Polymerization of isobutene

The number average molecular weight M _n , also referred to herein as the average molecular weight M _n , was determined using

Gel permeation chromatography (GPC) was determined using standardized polyisobutenes as calibration substances. The number average M _n was obtained from the GPC chromatograms obtained according to the equation

M _n = Σ Ci / ∑ (Ci / Mi)

calculated, where Ci stands for the concentration of the individual polymer species in the polymer mixture obtained and Mi for the molecular weight of the individual polymer species i. The molecular weight distribution, also called dispersity (D), was calculated from the ratio of the weight average (M _w ) and the number average (M _n ) according to the equation

D = M _w / M _n

determined, the weight average M _{w being determined} from the GPC chromatograms obtained using the following equation:

M _w = ∑ Ci Mi / ∑ ci The α- and ß-olefin content (formula I and II) was determined by ¹³ C-NMR spectroscopy. The C atoms of the terminal double bond of the α-olefins I show signals in the ¹³ C-NMR spectrum with a chemical shift of 114.4 ppm (CH ₂ ) and 5 143.6 ppm (C). The signals of the C atoms of the trisubstituted double bond of the β-olefins II are in the ¹³ C-NMR spectrum at 127.9 (= CH-R) and 135.4 ppm (= C (CH ₃ ) ₂ ) • By evaluating the Signal areas and comparison with the signal areas of the other olefinic carbon atoms, the content of α and β olefin 0 can be determined. Deuterated chloroform (CDC1 ₃ ) was used as the solvent and tetramethylsilane as the internal standard.

example 1

5 10 g of isobutene were condensed into a 25 ml glass pressure vessel under argon at -70 ° C. After addition of 1 g of catalyst A, which had previously been dried again at 180 ° C./0.3 mbar, the vessel was closed and the suspension was stirred at 0 ° C. for 2 hours under the autogenous pressure of the reaction system. The polymerization mixture was then diluted with 0 g of n-hexane at 0 ° C. Unreacted isobutene was evaporated at room temperature, the catalyst was filtered off and the added solvent was distilled off from the filtrate at room temperature and slowly reducing the pressure to 0.3 mbar. Low molecular weight isobutene oligomers were 5 separated from the polyisobutene obtained by Kugelrohr distillation at 120 ° C / 0.3 mbar. The colorless polyisobutene obtained in a yield of 60% had an average molecular weight of M _n = 760, a molecular weight distribution of D = 3.0 and a content of terminal double bonds (= α-olefin-

30 stop) of 85 mol%. The ß-olefin content was 4%.

Comparative example (analogous to embodiment 2 of JP-A 57-14538)

35 10 g raffinate I (45.4% isobutene, 28.5% butene-1, 15.1%

2-butenes, 11.0% butanes) were mixed with 10 g 12 -molybdatophosphoric acid (Merck, powder dried at 180 ° C / 0.3 mbar) at 80 ° C / 8 bar autogenous pressure for 1 hour in a glass autoclave under stirring 'implemented. Then the polymerization mixture was at -10 ° C

40 diluted with about 20 ml of n-hexane, and the volatile C ₄ compounds were evaporated at room temperature under normal pressure. After the catalyst had been separated off, the filtrate was freed from the added solvent at room temperature and slowly reducing the pressure to 0.3 mbar. Low molecular weight isobutene

45 noligomers were separated from the yellowish polyisobutene obtained by bulb tube distillation at 120 ° C./0.3 mbar. The obtained in a yield of 32% (based on the isobutene used) yellow polyisobutene had an average molecular weight of M _n = 310, a molecular weight distribution of D = 1.9 and a content of terminal double bonds (= α-olefin content) of only 14 mol%. The ß-olefin content was 15.

Claims

claims 1. Process for the preparation of halogen-free, reactive polyisobutene with a content of terminal double bonds of more than 50 mol% and an average molecular weight M _n of 500 to 5000 daltons by cationic polymerization of hydrocarbon mixtures containing isobutene or isobutene in the liquid phase, thereby characterized in that the polymerization at a temperature of -40 to + 10 ° C in In the presence of a dehydrated molybdato or tungstato heteropolyacid. 2. The method according to claim 1, characterized in that one uses a dehydrated molybdato heteropolyacid. 3. The method according to claim 1, characterized in that one uses heteropolyacids which have been calcined at temperatures of 250 to 500 ° C. 4. The method according to claim 1, characterized in that one uses heteropolyacids which have been calcined at 280 to 400 ° C. 5. The method according to claim 1, characterized in that one uses heteropolyacids which are applied to a carrier. 6. The method according to claim 1, characterized in that one carries out the reaction in the presence of molybdatophosphoric acid, vanadomolybdatophosphoric acid. 7. The method according to claim 1, characterized in that one carries out the reaction in the presence of applied on a support molybdatophosphoric acid or vanadatomolybdatophosphoric acid.