Preparation method of polyisobutene

Abstract

The invention relates to a method and a device for producing polyisobutene at low temperature.

Description

[0001] manual

[0002] This invention relates to a method and apparatus for preparing polyisobutylene at low temperatures.

[0003] Homopolymers and copolymers containing isobutylene with a number-average molecular weight (Mn) of 500 to 1,000,000 are prepared on an industrial scale under Lewis acid catalysis, typically at temperatures far below room temperature. The reaction temperature can be reduced to -90 °C.

[0004] The higher the desired number-average molecular weight (Mn) of polyisobutylene, the lower the reaction temperature typically needs to be. Therefore, low-molecular-weight polyisobutylene with a number-average molecular weight (Mn) of several thousand can be prepared at 0 °C or slightly below 0 °C. For polyisobutylene with a number-average molecular weight (Mn) of approximately 10,000, temperatures typically in the range of -10 °C to -30 °C are required. However, to prepare high-molecular-weight polyisobutylene with a molecular weight greater than 100,000, a reaction temperature not exceeding -50 °C is necessary.

[0005] EP 322241 A2 discloses a method for preparing polybutene with a molecular weight of 500 to 5000 by reacting isobutene in the presence of BF3 under certain reaction conditions.

[0006] EP 628575 A1 and WO 2013 / 62763 describe various reactors and their operating methods for the preparation of highly reactive polyisobutylene.

[0007] None of the above documents address energy management within reaction management.

[0008] US 6525149 B1 describes ionic polymerization in a tubular reactor, wherein the reaction mixture is circulated in a specific ratio to the monomer feed. The example discloses specific flow rates and dimensions of the reaction zone, but thermal management remains open.

[0009] US 2019 / 0118158 A1 describes ionic polymerization, such as the polymerization of isobutylene into polyisobutylene, in a heat exchanger reactor system (HERS), wherein the reactor system includes special channels in the form of parallelepipeds.

[0010] The disadvantage of this reactor system is its high manufacturing cost because the side surfaces must be welded. On the one hand, the welds are expensive to manufacture; on the other hand, they are a source of leakage and corrosion.

[0011] DE 102009019470 A1 discloses the cationic polymerization of monomers, wherein at least continuous mixing and preferably polymerization occur within microstructures. Microstructures allow for high heat exchanger surfaces, resulting in polymerization that can proceed almost isothermally; however, a drawback of microstructures is that they are quickly clogged by polymer deposits. Therefore, the reaction according to DE 102009019470 A1 is only carried out in a straight channel without a circulation procedure, because the circulating reaction mixture contains polymer, which would lead to the deposition or clogging of the microstructures.

[0012] These methods for preparing polyisobutylene are very energy-intensive due to the low reaction temperatures, especially for generating and maintaining low temperatures and for removing the heat of reaction at low temperature levels.

[0013] Because of the low reaction temperature, it is usually not necessary to use a favorable cooling medium, especially water, particularly river water, to remove the heat of reaction that polymerizes into polyisobutylene.

[0014] Therefore, the object of this invention is to provide a method and apparatus for preparing isobutylene homopolymers and copolymers, which reduces energy consumption for maintaining low temperatures and optimizes the energy efficiency of the apparatus. From a chemical perspective, isothermal reactions may be preferable, but they are uneconomical.

[0015] While cooling equipment and piping are typically isolated from ambient temperature, this isolation cannot be complete: to ensure the operability and accessibility of movable or otherwise easily accessible system components (such as pumps or fittings), insulation breaks down at multiple locations, creating thermal bridges. Through these thermal bridges, the contents of the equipment, fittings, and piping are heated at these locations, thus reducing energy efficiency. Furthermore, if the contents of the equipment and piping remain reactive at these locations due to the presence of undeactivated Lewis acids, the reaction is further accelerated by heating above the desired reaction temperature. This can lead to the formation of byproducts or, generally, product heterogeneity, as the reaction temperature, as mentioned above, strongly influences the reaction, particularly the molar mass distribution, resulting in high polydispersity of the products.

[0016] This objective is achieved by a method for preparing polyisobutylene with a number-average molecular weight (Mn) of 500 to 1,000,000 from isobutylene or a mixture of isobutylene-containing monomers, wherein the reaction is carried out in a reaction system.

[0017] -Its cooling surface O 冷却 The ratio to the reaction volume V is subject to the inequality.

[0018] O 冷却 / V ≥ 50 m 2 / m 3Preferably at least 55, particularly preferably at least 60, very particularly preferably at least 70, and especially at least 80 m 2 / m 3 ,and

[0019] -Its cooling surface O 冷却 With uncooled surface O 未冷却 The ratio is subject to the inequality

[0020] O 冷却 / O 未冷却 ≥ 5 [m 2 / m 2 [m] Preferably at least 7, particularly preferably at least 10, very particularly preferably at least 12 2 / m 2 ].

[0021] These measures keep the energy input into the reaction mixture through the surface of the reaction system as low as possible.

[0022] Another advantage is that the reaction temperature does not need to be kept below the temperature required for the desired polymerization result. Otherwise, the released polymerization energy would have to be consumed at a lower temperature level, which would reduce the efficiency of the chiller in producing the cooling medium.

[0023] definition

[0024] In the context of this specification, a reaction system is understood as the equipment portion of which isobutylene or an isobutylene-containing monomer mixture reacts with increasing number-average molecular weight Mn to yield polyisobutylene. This equipment specifically includes reactors, heat exchangers, pipelines, pumps, fittings, connections, and flanges, preferably reactors, heat exchangers, and pipelines. This is preferably the portion of the equipment where the isobutylene or isobutylene-containing monomer mixture contacts at least one Lewis acid. The reaction is typically terminated by deactivating at least one Lewis acid, for example, by adding water or an alcohol, preferably water. Therefore, the equipment portion and equipment in contact with the reaction mixture after the Lewis acid is deactivated are no longer considered part of the reaction system.

[0025] Therefore, the reaction system is particularly preferably understood as the part of the apparatus that contacts isobutylene or a mixture of isobutylene-containing monomers with an undeactivated Lewis acid, such that deactivated equipment is no longer added to the reaction system. Thus, very particularly preferably, the reaction system includes a reactor and heat exchangers, pumps, and pipelines leading from the reactor to the inlet of the deactivated equipment. Another possibility for terminating the reaction is to remove the monomeric isobutylene from the Lewis acid-containing reaction mixture, for example by distillation or extraction, preferably single-stage or multi-stage distillation. Complete conversion of the monomeric isobutylene is also conceivable. Typically, the reaction ceases when the reactive Lewis acid and the monomeric isobutylene are no longer in contact with each other.

[0026] In this case, the reaction system includes at least one part, such as one to three, preferably one or two, or particularly preferably one part, wherein the reaction mixture is in direct contact with a colder medium than the reaction mixture via a thermally conductive surface, and at least one part, such as one to three, preferably one or two, or particularly preferably not the case.

[0027] The reaction mixture is circulated through at least one cooled heat exchanger. Fresh feed containing isobutylene is added to this circulated reaction mixture, and a corresponding amount of reaction product is removed to maintain a constant total volume of the reaction mixture.

[0028] In order to homogenize the reaction mixture and the heat during the reaction process, the volume of the circulating reaction mixture is preferably at least 15 times that of the fresh feed containing isobutylene, preferably at least 20 times, and particularly preferably at least 25 times.

[0029] The volume of the fresh isobutylene-containing feed should not exceed 100 times, otherwise the energy used for pumping output will make the whole process uneconomical. Preferably, it should not exceed 80 times, particularly preferably 70 times, very particularly preferably 60 times, and especially preferably 50 times.

[0030] Furthermore, energy is introduced into the system through high pumping power, and this energy must then be removed from the reaction mixture through cooling. Therefore, pumping high circulation volumes is detrimental to optimizing energy efficiency.

[0031] The mixing of fresh isobutylene-containing feedstock with the reaction mixture is typically achieved through an energy input of shear energy. This can be carried out, for example, in a dynamic mixing device, i.e., by using an agitator or by pumping (natural or forced circulation), or by using a static mixing mechanism (e.g., a static mixer or a nozzle in a pumping circuit), via a static mixing device (e.g., a static mixer, nozzle, baffle, Y-shaped or T-shaped element) or via a dynamic mixing device (e.g., a mixing pump). Mixing is preferably carried out via a mixing section having a static mixer or nozzle, preferably a static mixer.

[0032] The heat exchanger here is selected from controlled tubular reactors, tube bundle heat exchangers, plate heat exchangers and controlled tubular reactors with built-in components, preferably tube bundle heat exchangers and plate heat exchangers, and particularly preferably tube bundle heat exchangers.

[0033] It is possible, but less preferred, to carry out the process in at least one stirred tank reactor or in a cascade of at least two stirred tank reactors, preferably two to five, and particularly preferably two to three stirred tank reactors, each cooled by a jacket and / or an internal heat exchanger.

[0034] The advantage of this invention is that it can be carried out in these conventional reactors and does not require the complex reactor system required under US 2019 / 0118158 A1.

[0035] Cooling surface O 冷却 These are the surfaces of all equipment parts of the reaction system that are in direct contact with a medium that is colder than the reaction mixture in the corresponding equipment part, through heat-conducting surfaces. The temperature difference between the colder medium and the reaction mixture is, for example, at least 5 K, preferably at least 8 K, particularly preferably at least 10 K, and very particularly preferably at least 12 K.

[0036] Temperature differences exceeding 30 K between the cooler medium and the reaction mixture are generally not advantageous; preferably, the difference is no greater than 25 K, particularly preferably no greater than 20 K, very particularly preferably no greater than 18 K, and especially no greater than 15 K. High temperature differences cause the reaction mixture to supercool near the walls, resulting in the formation of higher molecular weight polyisobutylene there. Furthermore, the viscosity there increases locally due to the lower temperature, making mixing more difficult and increasing the residence time on the reactor walls. As a result, the average molecular weight of the polyisobutylene becomes non-uniform, i.e., its polydispersity increases.

[0037] Cooler media can be, for example, brine, particularly ethylene glycol / water mixtures or ammonia. Organic hydrocarbons, such as propane, butane isomer mixtures, or ethylene, or partially or fully fluorinated hydrocarbons, can also be used.

[0038] Thermally conductive surfaces are, for example, the surfaces of heat exchanger tubes or plates, or the sheaths of reactors or tubes that guide cooler media.

[0039] In this case, O 冷却 This refers to the inner side of the surface that is in direct thermal contact with the reaction mixture, and any gas phase above it.

[0040] In contrast, the uncooled surface O 未冷却 This refers to the surface of all equipment parts located in the reaction system that is in direct thermal contact with a medium at a temperature higher than the reaction mixture. The inner side of the aforementioned surface is also used here. The medium at a temperature higher than the reaction mixture is preferably the ambient atmosphere present in every case. The corresponding surface is typically insulated from the outside, so it still has a higher temperature than the reaction mixture. Typical uncooled surfaces include pumps, fittings, valves, and piping, unless they are equipped with jackets (with accompanying cooling) to guide the cooler medium.

[0041] The location where the wall temperature is equal to or higher than the temperature of the reaction mixture is used to divide O. 冷却 and O 未冷却 And calculate the corresponding surface.

[0042] The reaction volume V is the total volume of the reaction system surrounded by the equipment components, in which isobutylene or a mixture of isobutylene-containing monomers reacts with increasing number-average molecular weight Mn. The preferred embodiments described above in defining the reaction system will be applied accordingly here.

[0043] In this case, the volume enclosed by the surface defined above is specified as the volume.

[0044] Considering the reaction volume, it may be meaningful to distinguish between pipelines and containers:

[0045] In this specification, pipeline refers to machines and equipment having the following surfaces: having a minimum length of 4 m. 2 / m 3 Preferably at least 8, particularly preferably at least, very particularly preferably at least 16, especially at least 40 m 2 / m 3 The volume ratio (O / V). These are especially pipes with a nominal width (NW) of 100 mm to 1000 mm, preferably 300 mm to 500 mm.

[0046] Whether the surface is cooled or not is irrelevant.

[0047] For example, an NW 100mm pipe has approximately 40 m 2 / m 3 The O / V ratio is 16 m for NW 250mm. 2 / m 3 The O / V of NW1000mm is 4 m. 2 / m 3 The O / V ratio depends only on the pipe radius r: O / V = 2 / r.

[0048] In this specification, a container refers to a machine or device with a small surface area: having the same volume ratio as pipelines as defined above.

[0049] Assuming the container is an ideal cylinder with a round, flat bottom and a lid, the typical O / V ratio for a radius r of 0.5 m and a height h = 1 m is O / V = 6 m. 2 / m 3 When r = 1 m and h = 1 m, O / V = 4; when r = 0.5 m and h = 0.5 m, O / V = 8; and when r = 1 m and h = 5 m, O / V = 2.4 m. 2 / m 3 Typically, O / V = (2×h + 2×r) / (r×h) applies to such an ideal cylinder.

[0050] These O / V ratios show that in order to achieve the O according to the present invention 冷却 / V ≥ 50 m 2 / m 3 The ratio of O / V has a significant impact on cooling, especially on pipelines, because, according to the above definition, it has a high O / V ratio, that is, the surface area available for heat exchange relative to its volume. 冷却 The ratio of / V is preferably at least 55, particularly preferably at least 60, very particularly preferably at least 70, and especially at least 80 m 2 / m 3 .

[0051] Preferably not exceeding 250 m 2 / m 3 O 冷却 / V ratio, with O being particularly preferred 冷却 / V ratio not greater than 200, with a very special preference not greater than 175, and especially not greater than 150 m 2 / m 3 High O 冷却 The / V ratio is essential for achieving isothermal reactions, but it is unnecessary for the energy efficiency optimization according to the present invention.

[0052] According to the present invention, the ratio of uncooled surface to cooled surface must be at least 5 [m] 2 / m 2 [m] Preferably at least 7, particularly preferably at least 10, very particularly preferably at least 12 2 / m 2 ].

[0053] Therefore, relative to the inlet temperature entering the uncooled reaction system, the temperature rise in the uncooled reaction system can be limited to no more than 2.5 K, preferably no more than 2.2 K, particularly preferably no more than 2.0 K, and very particularly preferably no more than 1.8 K. Due to this limitation on temperature rise, the reaction mixture is subject to smaller temperature fluctuations, which will result in a non-uniform product mixture.

[0054] On the other hand, isothermal reaction is not required, i.e., no temperature rise is needed. However, isothermal reactions require a large cooling surface area. It has been found that in uncooled reaction systems, a temperature rise of 0.3 K or higher is acceptable without making the product mixture excessively inhomogeneous, preferably 0.5 K or higher, particularly preferably 0.75 K or higher, very particularly preferably 1.0 K or higher, and especially 1.5 K or higher.

[0055] The present invention also provides a production apparatus for preparing polyisobutylene, comprising at least the following equipment parts:

[0056] - At least one device for providing a mixture of isobutylene-containing monomers selected from pipelines, tanks, and buffer containers.

[0057] - At least two storage containers for at least one Lewis acid and at least one co-catalyst

[0058] - A metering device for adding at least one Lewis acid and at least one co-catalyst to a monomer mixture containing isobutylene.

[0059] Refrigeration equipment

[0060] - At least one reaction system for reacting a mixture of monomers containing isobutylene, comprising at least one reactor, a heat exchanger, and pipelines.

[0061] - At least one container for terminating the reaction by metering water or alcohol, and

[0062] - At least one distillation apparatus for processing the reaction mixture,

[0063] in

[0064] In the reaction system, the cooling surface O 冷却 The ratio to the reaction volume V is subject to the inequality.

[0065] O 冷却 / V ≥ 50 m 2 / m 3 Preferably at least 55, particularly preferably at least 60, very particularly preferably at least 70, and especially at least 80 m 2 / m 3 ,and

[0066] -Its cooling surface O 冷却 With uncooled surface O 未冷却 The ratio is subject to the inequality

[0067] O 冷却 / O 未冷却 ≥ 5 [m 2 / m 2 [m] Preferably at least 7, particularly preferably at least 10, very particularly preferably at least 12 2 / m 2 ].

[0068] The implementation scheme of this method is also applicable to the production equipment according to the present invention.

[0069] The present invention also provides the use of such production equipment for preparing polyisobutylene with a number average molecular weight Mn of 500 to 1,000,000 from isobutylene or a mixture of isobutylene-containing monomers.

[0070] The present invention also provides a method for preparing polyisobutylene from a mixture of isobutylene monomers in the presence of at least one Lewis acid in such a production facility.

[0071] In the context of this specification, polyisobutylene is understood to be a homopolymer and copolymer of isobutylene in a copolymeric form.

[0072] In one preferred embodiment, pure isobutene and in another preferred embodiment, C4 hydrocarbon streams containing isobutene, such as C4 residues, particularly "Residue 1," C4 fractions from isobutane dehydrogenation, and C4 fractions from steam crackers and FCC crackers (fluidized catalytic cracking), are suitable as isobutene sources, provided they are substantially free of 1,3-butadiene present therein. C4 hydrocarbon streams from FCC refining units are also referred to as "b / b" streams. Other suitable isobutene-containing C4 hydrocarbon streams are, for example, product streams from propylene-isobutane co-oxidation or product streams from metathesis units, which are typically used after conventional purification and / or concentration. Suitable C4 hydrocarbon streams typically contain less than 500 ppm, preferably less than 200 ppm, of butadiene. The presence of 1-butene, as well as cis- and trans-2-butene, is largely unimportant. Typically, the isobutene concentration in the C4 hydrocarbon stream is in the range of 40-60% by weight. Therefore, residual liquid 1 typically consists essentially of 30 to 50 wt% isobutylene, 10 to 50 wt% 1-butene, 10 to 40 wt% cis- and trans-2-butene, and 2 to 35 wt% butane; in the polymerization method according to the invention, the butene not shown in residual liquid 1 is generally practically inert, and only isobutylene is polymerized. In a preferred embodiment, a C4 hydrocarbon stream, particularly residual liquid 1 stream, b / b stream from the FCC refining unit, product stream from propylene-isobutane co-oxidation, or product stream from the metathesis unit, containing 1 to 100 wt% isobutylene, particularly 1 to 99 wt%, particularly 1 to 90 wt%, particularly 30 to 60 wt%, is used as the monomer source for polymerization.

[0073] The isobutylene content in the C4 hydrocarbon stream is preferably at least 40% by weight, and particularly preferably at least 45% by weight.

[0074] In particular, when using residual liquid stream 1 as the isobutylene source, it has been shown that using water as the sole or other initiator is useful, especially when polymerization is carried out at temperatures ranging from -20 °C to +30 °C, particularly from 0 °C to +20 °C. However, at temperatures ranging from -20 °C to +30 °C, particularly from 0 °C to +20 °C, when using residual liquid stream 1 as the isobutylene source, the use of an initiator can also be omitted.

[0075] The isobutylene-containing monomer mixture may contain small amounts of contaminants, such as water, carboxylic acids, or inorganic acids, without causing a critical loss in yield or selectivity. Advantageously, the enrichment of these contaminants is avoided by removing them from the isobutylene-containing monomer mixture, for example, by adsorption onto solid adsorbents such as activated carbon, molecular sieves, or ion exchangers.

[0076] The proportion of comonomers other than isobutylene in polyisobutylene is generally no more than 10% by weight, preferably no more than 7.5% by weight, particularly preferably no more than 5% by weight, very particularly preferably no more than 2.5% by weight, and especially no more than 1% by weight.

[0077] According to the method of the present invention, polyisobutylene with a number average molecular weight Mn of 500 to 1,000,000, preferably 500 to 250,000, particularly preferably 550 to 200,000, very particularly preferably 650 to 100,000, especially 750 to 50,000 g / mol can be prepared.

[0078] Polydispersity, i.e., the quotient of weight-average molecular weight Mw and number-average molecular weight Mn (PDI=M w / M n The PDI ranges from 1.05 to 3.5, preferably from 1.05 to 2.5, particularly from 1.05 to 2.0, and especially from 1.1 to 1.85. Under optimal process control, the typical PDI value is from 1.2 to 1.7.

[0079] The molecular weight was determined by gel permeation chromatography using polystyrene as a standard.

[0080] Among these polyisobutylenes, those with a high content of terminally arranged ethylene double bonds (α-double bonds) are preferred, particularly those with an α-double bond content of at least 50 mol%, preferably at least 60 mol%, particularly preferably at least 70 mol%, very particularly preferably at least 80 mol%, and especially at least 90 mol%. These are referred to as highly reactive polyisobutylenes, where the formation of terminal ethylene unsaturated double bonds is particularly sensitive to changes in reaction temperature.

[0081] Depending on the desired polyisobutylene molecular weight, the method according to the invention is carried out at different reaction temperatures:

[0082] In a preferred embodiment of the present invention, when seeking polyisobutylene with a number average molecular weight Mn of 500 to 5000, the reaction temperature in the reaction mixture is preferably -5 (-5) to 25 °C.

[0083] The homopolymer or copolymer is particularly preferably highly reactive polyisobutylene, having a terminal vinyl group content of at least 70 mol%, preferably at least 80 mol%, and particularly preferably at least 90 mol%.

[0084] In another preferred embodiment of the present invention, when the desired number-average molecular weight Mn is 10,000 to 100,000, the reaction temperature in the reaction mixture is preferably -10 to -30 °C.

[0085] In another preferred embodiment of the invention, when the desired number-average molecular weight Mn is at least 150,000 to 1,000,000, the reaction temperature in the reaction mixture is preferably -50 to -90 °C.

[0086] Without complete mixing (e.g., by circulation, stirring or backmixing), the average residence time in the reaction system should generally be less than 2 hours, preferably less than 90 minutes, and particularly preferably less than 60 minutes.

[0087] Polymerization is typically carried out at pressures ranging from 700 mbar to 20 bar, particularly from 1 bar to 10 bar, and especially from 1.2 bar to 7 bar. Overpressure is generally advantageous for the C4 hydrocarbon mixture used and for any optional inert diluents.

[0088] In principle, all types of reactors suitable for this type of liquid-phase polymerization, whether batch or continuous, can be used as polymerization reactors according to the method of the invention, such as stirred tanks, stirred tank cascades, tubular reactors, or circulating reactors. If the polymerization according to the method of the invention is carried out at or above the boiling point of the inert diluent or the monomer to be polymerized, it is preferably carried out in a pressure vessel, such as an autoclave or pressure reactor.

[0089] In addition, it is important to move the polymerizable compound within the container, for example by stirring, natural circulation, or pumping (forced circulation).

[0090] The polymerization according to the method of the present invention can be carried out in the presence of an inert diluent. The inert diluent used should be able to reduce the increase in viscosity of the reaction solution that usually occurs during the polymerization reaction, so as to ensure that the generated heat of reaction is carried away. Suitable diluents are solvents or solvent mixtures that are inert to the reagents used. Examples of suitable diluents are aliphatic hydrocarbons such as n-butane, n-pentane, n-hexane, n-heptane, n-octane and isooctane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; and halogenated hydrocarbons, especially halogenated aliphatic hydrocarbons such as chloromethane, dichloromethane, trichloromethane (chloroform), 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane and 1-chlorobutane; and halogenated aromatic hydrocarbons and halogenated alkyl aromatic hydrocarbons in alkyl side chains such as chlorobenzene, monofluoromethylbenzene, difluoromethylbenzene and trifluoromethylbenzene; and mixtures of the above diluents. Advantageously, the diluent is released from impurities such as water or inorganic acids before use, for example, by adsorption onto a solid adsorbent such as activated carbon, molecular sieve, or ion exchanger. Of course, the inert portion of the isobutylene-containing C4 hydrocarbon mixture used as a raw material is also used as a component of the diluent or the solvent mixture.

[0091] In a preferred embodiment, no further diluent that increases the heat capacity of the reaction mixture and must be cooled is added to the reaction mixture.

[0092] The reaction mixture can be single-phase or multi-phase, preferably single-phase. Typically, gaseous, liquid, and solid components exist side by side, and the reaction mixture is preferably kept liquid, wherein solid components, such as polymers or Lewis acids, may also be present in the liquid reaction mixture.

[0093] The polymerization according to the method of the invention is preferably carried out under substantially aprotic reaction conditions, particularly under substantially anhydrous reaction conditions. Substantially aprotic or substantially anhydrous reaction conditions mean that the water content (or the content of protic impurities) in the reaction mixture is less than 50 ppm by weight, particularly less than 5 ppm by weight. Therefore, the raw materials are typically dried by physical and / or chemical measures before use. In particular, it has been shown that, after routine pre-purification and pre-drying, an organometallic compound, such as an organolithium, organomagnesium, or organoaluminum compound, is added to the aliphatic or alicyclic hydrocarbon used as a diluent in an amount sufficient to substantially remove water traces from the solvent. The solvent treated in this way is then preferably condensed directly into the reaction vessel. Mixtures of C4 hydrocarbons containing isobutylene can also be carried out in a similar manner. Drying with other conventional drying agents such as molecular sieves or pre-dried oxides such as alumina, silica, calcium oxide, or barium oxide is also suitable. Halogenated solvents unsuitable for drying with metals such as sodium or potassium or metallic alkyl groups are removed from water or water traces using suitable drying agents such as calcium chloride, phosphorus pentoxide, or molecular sieves.

[0094] To terminate the reaction, the reaction mixture is preferably deactivated, for example by adding sufficient protonated compounds, particularly by adding water, alcohols such as methanol, ethanol, n-propanol and isopropanol or mixtures thereof with water, or by adding an aqueous base, such as an aqueous solution of alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide or calcium hydroxide, an aqueous solution of alkali metal or alkaline earth metal carbonates such as sodium carbonate, potassium carbonate, magnesium carbonate or calcium carbonate, or an aqueous solution of alkali metal or alkaline earth metal bicarbonates such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate or calcium bicarbonate.

[0095] The treatment of the reaction mixture includes at least one phase separation, wherein water, alcohol, or an aqueous solution added to terminate the reaction is separated from the organic phase of the reaction mixture. This may optionally be supported by washing the reaction mixture with additional water or an aqueous solution.

[0096] The low-boiling-point compounds present in the reaction mixture are then removed by distillation.

[0097] Low-boiling-point compounds can be unreacted isobutylene, unreacted components of C4 hydrocarbon streams used as starting materials, and solvents. Lower oligomers, such as diisobutylene and triisobutylene, are also isolated.

[0098] Unreacted isobutylene and lower oligomers are preferably recycled at least partially into the reaction.

[0099] The distillation separation of these low-boiling-point compounds can be carried out in batches, or preferably continuously, and in single or multiple stages, preferably single or two stages, particularly two stages. Continuous and at least two-stage distillation separation is preferred, wherein in each case, the final stage is carried out under vacuum, for example from 10 mbar to atmospheric pressure, preferably 20 to 900 mbar, particularly preferably 30 to 800 mbar, at a temperature of 60 to 250 °C, preferably 80 to 200 °C, particularly preferably 100 to 190 °C.

[0100] Of course, distillation can also be carried out in falling film, thin film, or wiper blade evaporators. For this purpose, the mixture is preferably circulated through the equipment several times under reduced or normal pressure, for example from 10 mbar to normal pressure, preferably 20 to 900 mbar, particularly preferably 30 to 800 mbar, at a temperature of 60 to 250 °C, preferably 80 to 200 °C, particularly preferably 100 to 190 °C.

[0101] An inert gas, preferably argon or a nitrogen-containing gas, particularly preferably argon, nitrogen or a mixture of air and nitrogen (lean air), very particularly preferably nitrogen, can be advantageously introduced into the distillation apparatus, for example 0.1-1, preferably 0.2-0.8, particularly preferably 0.3-0.7 m³ / m³h, based on the volume of the liquid mixture.

[0102] In a particularly preferred variant, degassing can also be carried out in a container with built-in components that promote degassing.

[0103] Possible devices for degassing include blade dryers with or preferably without a cooling zone, and optionally with a forced discharge mechanism.

[0104] This type of usable blade dryer preferably has no separation between the heating and cooling zones to prevent sudden temperature drops. Instead, the temperature of the residue increases as it passes through the equipment, preferably by increasing the temperature gradient, which varies by no more than 50 °C during the passage of the residue. Particularly preferred is that there is no significant temperature change during the passage of the residue, i.e., less than 20 °C, and especially less than 10 °C.

[0105] These blade dryers are generally horizontally designed, and the residue is typically conveyed through one or two mixing and kneading shafts inside the device. In technical literature, these devices are also referred to as particle bed reactors, kneading dryers, or kneading reactors.

[0106] Preferably, the blade dryer has forced conveying in the axial direction. For example, forced conveying is achieved by tilting the surface of the conveying element.

[0107] Axial transport of the equipment can preferably be achieved through the arrangement of conveying, kneading and / or mixing elements, such as disc elements, shafts, screws, blades, wipers or rotors.

[0108] To shorten the residence time distribution in the blade dryer, the product conveyor is preferably divided into different sections by membrane-like discs. It is particularly preferred to use at least two discs.

[0109] Heating is performed through the walls and can be performed in any desired manner. Preferably, heating is performed not only through the outer walls of the device but also through built-in components such as cleaning hooks, segmented discs, and kneading shafts.

[0110] The thermal energy introduced into the reactor contents through the wall is typically greater than 120 kJ / kg reactor contents and less than 2400 kJ / kg reactor contents, preferably greater than 220 kJ / kg reactor contents and less than 1800 kJ / kg reactor contents, particularly preferably greater than 300 kJ / kg reactor contents and less than 1400 kJ / kg reactor contents, and very particularly preferably greater than 360 kJ / kg residue and less than 900 kJ / kg reactor contents.

[0111] The heating distance of the reaction mixture supplied to the blade dryer is preferably greater than 10% and less than 70% of the total length of the blade dryer, more preferably greater than 20% and less than 60% of the total length of the blade dryer, and particularly preferably greater than 30% and less than 50%.

[0112] In this apparatus, a mechanical energy input of 5 W / kg or greater is generally sufficient, preferably 10 W / kg or greater, particularly preferably 20 W / kg or greater, very particularly preferably 40 W / kg or greater, especially 80 W / kg or greater, and especially 100 W / kg or greater. Typically, an energy input exceeding 200 W / kg provides no benefit. The specific power input given here is the input power for each metered amount of reaction mixture in the apparatus.

[0113] Furthermore, it is advantageous that the blade dryer provides forced cleaning of at least 50%, preferably at least 60%, very particularly preferably at least 70%, and especially at least 80% of these internal product contact surfaces. Forced cleaning is ensured by bringing the conveying element close to the outer wall or by bringing the cleaning hook close to the conveying element.

[0114] Such devices are, for example, produced by List AG of Arisdorf, Switzerland, under the trade name Discotherm. ® Provided by B or List-CRP or AP, and by Buss-SMS-Canzler GmbH of Butzbach, Germany, under the trade name Reasol ® or Reactotherm ® supply.

[0115] Optionally, a discharge mechanism, such as a screw, preferably a twin-screw, may be provided for forcibly discharging the reaction effluent.

[0116] However, in most cases, the mechanical conveying equipment of the equipment is sufficient to discharge the product from the equipment.

[0117] Suitable Lewis acids are preferably boron halides, such as boron trichloride, boron trifluoride or boron tribromide, with boron trifluoride being the most preferred.

[0118] The reactivity of boron halides is modulated by one or more co-catalysts, which together form complexes with the boron halides.

[0119] The preferred co-catalyst is:

[0120] C1-C5 alkanols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, and tert-butanol. These alkanols are also preferably used as mixtures of two alkanols, preferably mixtures of primary and secondary alcohols.

[0121] Aldehydes or ketones having 1 to 20, preferably 2 to 10, carbon atoms, such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, acetone, methyl ethyl ketone, or diethyl ketone.

[0122] Ethers having 2 to 10 carbon atoms, such as dialkyl ethers or cyclic ethers. Examples include dimethyl ether, diethyl ether, diisopropyl ether, di-n-butyl ether, tert-butyl ether, butyl methyl ether, bis(chloroethyl) ether, chloroethyl ethyl ether, tetrahydrofuran, or dioxane.

[0123] Carboxylic acid esters having 2 to 20 carbon atoms, such as formic acid-C1-C4-alkyl esters, acetic acid-C1-C4-alkyl esters, or butyric acid-C1-C4-alkyl esters.

[0124] The molar ratio of boron trihalide to the total of all cocatalysts is typically 2:1 to 1:10, preferably 1.5:1 to 1:5, particularly 1.25:1 to 1:2, and especially 1:1 to 1:1.5. The amount of cocatalyst can affect the adjustment of the molecular weight of the isobutylene homopolymer to be obtained, and therefore can be used to selectively adjust its molecular weight.

[0125] The amount of polymerization catalyst to be used depends largely on the type of co-catalyst and reaction conditions, particularly the reaction temperature and the desired molecular weight of the polymer. It can be determined by performing minimal puncture tests on the corresponding reaction system. Polymerization catalysts are typically used in amounts from 0.0001 to 1% by weight, particularly 0.0005 to 0.5% by weight, and especially 0.001 to 0.1% by weight, depending in each case on the boron trihalide content in the catalyst complex and the amount of isobutylene used.

[0126] Besides the preferred boron trihalide, the Lewis acid can also be aluminum halide, C1-C4 alkyl aluminum halide, C1-C4 alkoxy aluminum halide, C1-C4 alkoxy-C1-C4 alkyl aluminum halide, iron halide, gallium halide, titanium halide, zinc halide, tin dihalide, and tin tetrahalide. Among these, aluminum halide, C1-C4 alkyl aluminum halide, iron halide, and titanium halide are preferred, aluminum halide and C1-C4 alkyl aluminum halide are particularly preferred, and aluminum halide is very particularly preferred.

[0127] Among halides, chlorides and bromides are preferred for the Lewis acids mentioned last, with chlorides being particularly preferred.

[0128] The Lewis acids mentioned last are also used in conjunction with the aforementioned co-catalysts, and the type and amount of co-catalysts are also suitable for these Lewis acids.

[0129] The advantage of the method according to the invention is that it improves the energy efficiency of the manufacturing process because the energy input from the outside to the reaction mixture is reduced, the released heat of reaction can be dissipated at a higher temperature level, which improves the efficiency of the refrigeration unit and / or allows the use of less solvent or diluent.

[0130] Therefore, by improving energy efficiency, the energy consumption of this process is reduced, which indirectly reduces emissions related to energy supply.

[0131] Therefore, another subject of the invention is a method for reducing emissions, particularly carbon dioxide emissions, preferably identified as a carbon footprint or life cycle assessment, particularly preferably according to DIN EN ISO 14021, DIN EN ISO 14067, in this case particularly the 2019-02 edition, DIN EN ISO 14044, in this case particularly the 2006+A1:2018 edition and / or DIN EN ISO 14040, in this case particularly the 2009-11 edition, wherein polyisobutylene is prepared by the method according to the invention.

[0132] Furthermore, thanks to the measures according to the invention, the reaction temperature remains more constant than when no measures are used. Without these measures, the reaction temperature in the reaction mixture would be higher, leading to an increased formation of higher molecular weight polyisobutylene. This is particularly true because the molecular weight of the formed polyisobutylene is temperature-dependent, resulting in increased inhomogeneity of the polyisobutylene molecular weight, manifested as increased polydispersity. Therefore, the measures according to the invention reduce the polydispersity of polyisobutylene in this method. Example

[0133] The reaction system for preparing polyisobutylene with a molecular weight of approximately 1000 g / mol consists of a circulating reactor, which can be divided into two sub-regions: a heat exchanger (cooling the reaction volume) (with the reaction temperature -15 °C as the initial temperature of the heat exchanger), which consists of a bundle of tube heat exchangers with the following dimensions and specifications, in which the reaction medium (residual liquid 1, isobutylene content 46 wt%, feed temperature 4 °C) circulates through the ring and within the tubes by means of a pump. Outside the tubes, but inside the bundle of tube heat exchangers, a cooling medium (boiling-point liquid ammonia) ensures the removal of the heat of reaction. The inner surfaces of these heat exchanger tubes represent the cooling surfaces.

[0134] The second part of the reaction system essentially consists of a ring required to maintain the movement of the reaction medium via pumping equipment, thereby ensuring that isobutylene, the formed polymer, and the diluent are distributed as uniformly as possible. Simultaneously, pumping the reaction medium in a desired manner facilitates heat transfer in the heat exchanger. The surface of the ring is typically insulated, but due to its design, it is generally not cooled. Therefore, the inner surfaces of all pipes and equipment within the ring (e.g., pumping equipment) represent uncooled surfaces.

[0135] The temperature drop across the heat exchanger, i.e., the difference between the outlet and inlet temperatures of the cooler, is used as a measure of the efficiency of the tube bundle heat exchanger. This is a measure of the heat removed from the uncooled reaction volume. The smaller the temperature drop, the more uniform the polymerization reaction temperature remains.

[0136] Example 1

[0137] In accordance with the energy-saving invention Implementation In the example, the reactor of the cooled tube bundle heat exchanger is characterized by the following data:

[0138] Number of pipes: 1356 Pipe diameter: 0.016 m Pipe length: 3.00 m Area of ​​the sheath for each pipe: 0.15 m² Volume of each pipe: 0.0006 m³ Total cooling area: 204.5 m² Pipe volume (cooling reactor volume): 0.82 m³

[0139] The uncooled loop of the reaction system is characterized by the following data:

[0140] Inhalation side length: 7.00 m Pressure side length: 8.00 m diameter: 0.40 m Ring area: 18.85 m² Ring volume: 1.88 m³ +Volume at the bottom of every 2 spools 0.4 m³ +Area at the bottom of every two spools <![CDATA[0.7 m 2 ]]> The outer surface of the reactor (0.9 m in diameter, 3 m in length) <![CDATA[8.5 m 2 ]]> Uncooled total area <![CDATA[28.75 m 2 ]]> <![CDATA[O 冷却 The 未冷却 ]]> <![CDATA[7.11 [m 2 / m 2 ]]]> Total area of ​​the reaction system: <![CDATA[223.3 m 2 ]]> Total volume of the cooling reaction system: 0.82 m³ Total volume of the uncooled reaction system: <![CDATA[2.68 m 3 <!-- 10 -->]]> Total volume <![CDATA[3.50 m 3 ]]>

[0141] The ratio of cooling surface area to total volume: 204.5 m² / 3.50 m³ = 58.4 m 2 / m 3

[0142] The ratio of cooled surface to uncooled surface: 204.5 m² / 28.75 m² = 7.11 [m 2 / m 2 ]

[0143] Temperature drop on the cooler: -1.9 K

[0144] Example 2

[0145] In accordance with the energy-saving invention Implementation In the example, the reactor of the cooled tube bundle heat exchanger is characterized by the following data:

[0146] Number of pipes: 1356 Pipe diameter: 0.016 m Pipe length: 8.00 m Area of ​​the sheath for each pipe: 0.40212 m² Volume of each pipe: 0.0016 m³ Total cooling area: 545.28 m² Pipe volume (cooling reactor volume): 2.18 m³

[0147] The uncooled loop of the reaction system is characterized by the following data:

[0148] Inhalation side length: 7.00 m Pressure side length: 8.00 m diameter: 0.40 m Ring area: 18.85 m² Ring volume: 1.88 m³ +Volume at the bottom of every 2 spools 0.4 m³ +Area at the bottom of every two spools <![CDATA[0.7 m 2 ]]> The outer surface of the reactor (0.9 m in diameter, 8 m in length) <![CDATA[22.6 m 2 ]]> Uncooled total area <![CDATA[42.85 m 2 ]]> <![CDATA[O 冷却 The 未冷却 ]]> <![CDATA[12.73 [m 2 / m 2 ]]]> Total area of ​​the reaction system: <![CDATA[588.1 m 2 ]]> Total volume of the cooling reaction system: 2.18 m³ Total volume of the uncooled reaction system: <![CDATA[2.68 m 3 ]]> Total volume (cooled + uncooled) <![CDATA[4.86 m 3 ]]>

[0149] The ratio of cooling surface area to total volume: 588.1 m² / 4.86 m³ = 121.0 [m 2 / m 3 ]

[0150] The ratio of cooled surface to uncooled surface: 588.1 m² / 42.85 m² = 13.7 [m] 2 / m 2 ]

[0151] Temperature drop on the cooler: -1.3 K

[0152] The temperature drop in the cooler is offset by an equally high temperature rise due to the heat of reaction released in the uncooled portion of the reaction system, which is carried away in the cooler.

[0153] It can be seen that with the development of the O 冷却 / V or O 冷却 / O 未冷却 As the concentration increases, the temperature rise in the reaction system decreases, thus exposing the reaction system to smaller temperature fluctuations.

Claims

1. A method for preparing polyisobutylene with a number-average molecular weight Mn of 500 to 1,000,000 from isobutylene or a mixture of isobutylene-containing monomers, characterized in that, The reaction takes place in the reaction system. -Its cooling surface O 冷却 The ratio to the reaction volume V is subject to the inequality. O 冷却 / V ≥ 50 m 2 / m 3 Preferably at least 55, particularly preferably at least 60, very particularly preferably at least 70, especially at least 80 m 2 / m 3 ,and -Its cooling surface O 冷却 With uncooled surface O 未冷却 The ratio is subject to the inequality O 冷却 / O 未冷却 ≥ 5 [m 2 / m 2 [m], preferably at least 7, particularly preferably at least 10 2 / m 2 [A very special preference is given to at least 12.] The reaction mixture is circulated through at least one cooled heat exchanger, and the circulated reaction mixture is introduced into a feed containing isobutylene, and a corresponding amount of isobutylene is removed from the circulation. The heat exchanger is selected from controllable tubular reactors, tube bundle heat exchangers, plate heat exchangers, and controllable tubular reactors with built-in components.

2. The method according to claim 1, characterized in that, Cooling surface O 冷却 The ratio of VO to the reaction volume 冷却 / V not exceeding 250 m 2 / m 3 The value of .

3. The method according to claim 1 or 2, characterized in that, The monomer mixture containing isobutylene is pure isobutylene.

4. The method according to claim 1 or 2, characterized in that, The monomer mixture containing isobutylene is a C4 hydrocarbon stream, which, in addition to isobutylene, also contains 1-butene and cis- and trans-2-butene.

5. The method according to any one of the preceding claims, characterized in that, The reaction is carried out in the presence of at least one Lewis acid selected from boron halide, aluminum halide, C1-C4 alkyl aluminum halide, C1-C4 alkoxy aluminum halide, C1-C4 alkoxy-C1-C4 alkyl aluminum halide, iron halide, gallium halide, titanium halide, zinc halide, tin dihalide and tin tetrahalide.

6. The method according to claim 5, characterized in that, In addition to Lewis acids, at least one cocatalyst selected from C1-C5 alkanols, aldehydes or ketones having 1 to 20 carbon atoms, ethers having 2 to 10 carbon atoms, and carboxylic acid esters having 2 to 20 carbon atoms is used.

7. The method according to any one of the preceding claims, characterized in that, Cooling surface O 冷却 When in contact with a cooling medium, the temperature difference between the medium and the reaction mixture is at least 5K.

8. The method according to any one of the preceding claims, characterized in that, Cooling surface O 冷却 When in contact with the cooling medium, the temperature difference between it and the reaction mixture should not exceed 30 K.

9. The method according to any one of the preceding claims, characterized in that, The volume of the circulating reaction mixture is preferably at least 15 times and no more than 100 times that of the fresh isobutylene-containing feed.

10. The method according to any one of the preceding claims, characterized in that, Compared to the inlet temperature of the uncooled reaction volume, the temperature rise in the uncooled reaction volume shall not exceed 2.5 K, preferably not more than 2.2 K, particularly preferably not more than 2.0 K, and very particularly preferably not more than 1.8 K.

11. The method according to any one of the preceding claims, characterized in that, The temperature rises by 0.3 K or higher in the uncooled reaction volume.

12. The method for preparing polyisobutylene with a number-average molecular weight Mn of 500 to 5000 according to any one of the preceding claims, characterized in that, The reaction temperature in the reaction mixture is -5 to 25 °C.

13. The method for preparing polyisobutylene with a number-average molecular weight Mn of 10,000 to 100,000 according to any one of claims 1 to 9, characterized in that, The reaction temperature in the reaction mixture is -10 to -30 °C.

14. The method for preparing polyisobutylene with a number-average molecular weight Mn of 150,000 to 1,000,000 according to any one of claims 1 to 9, characterized in that, The reaction temperature in the reaction mixture is -50 to -90 °C.

15. A method for reducing emissions, particularly carbon dioxide emissions, from the preparation of polyisobutylene with a number-average molecular weight Mn of 500 to 1,000,000 from isobutylene or a mixture of isobutylene-containing monomers, preferably determined by carbon footprint or life cycle assessment, particularly preferably according to DIN EN ISO 14021, DIN EN ISO 14067, in this case particularly the 2019-02 edition, DIN EN ISO 14044, in this case particularly the 2006+A1:2018 edition, and / or DIN EN ISO 14040, in this case particularly the 2009-11 edition, characterized in that, Polyisobutylene is prepared by any one of claims 1 to 11.

16. Use of an apparatus for producing polyisobutylene with a number-average molecular weight Mn of 500 to 1,000,000 from isobutylene or a mixture of isobutylene-containing monomers, comprising at least the following equipment components: - At least one device for providing a mixture of isobutylene-containing monomers selected from pipelines, tanks, and buffer containers. - At least two storage containers for at least one Lewis acid and at least one co-catalyst - A metering device for adding at least one Lewis acid and at least one co-catalyst to a monomer mixture containing isobutylene. Refrigeration equipment - At least one reaction system for reacting a mixture of monomers containing isobutylene, comprising at least one reactor, a heat exchanger, and pipelines. in, The heat exchanger is selected from controlled tubular reactors, tube bundle heat exchangers, plate heat exchangers, and controlled tubular reactors with built-in components. The reaction mixture can be circulated through at least one cooled heat exchanger. - At least one container for terminating the reaction by metering water or alcohol, and - At least one distillation apparatus for processing the reaction mixture, in In the reaction system, the cooling surface O 冷却 The ratio to the reaction volume V is subject to the inequality. O 冷却 / V ≥ 50 m 2 / m 3 Preferably at least 55, particularly preferably at least 60, very particularly preferably at least 70, especially at least 80 m 2 / m 3 ,and -Its cooling surface O 冷却 With uncooled surface O 未冷却 The ratio is subject to the inequality O 冷却 / O 未冷却 ≥ 5 [m 2 / m 2 [m] Preferably at least 7, particularly preferably at least 10, very particularly preferably at least 12 2 / m 2 ].