Method for producing polyisobutene

Abstract

The present invention relates to a process and apparatus for producing polyisobutene at low temperatures.

Description

Technical Field

[0001] The present invention relates to a process and an apparatus for producing polyisobutene at low temperatures. Background Art

[0002] Isobutene-containing homo- and copolymers having a number average molecular weight Mn of from 500 to 1,000,000 are generally produced on an industrial scale under Lewis acid catalysis at temperatures sufficiently lower than room temperature. The reaction temperature can be lowered to -90°C.

[0003] In general, the higher the desired number average molecular weight Mn of polyisobutene, the lower the reaction temperature. For example, low molecular weight polyisobutene having a number average molecular weight Mn of up to several thousand can be produced at about 0°C or a slightly lower temperature. For polyisobutene having a number average molecular weight Mn of tens of thousands, a temperature in the range of -10°C to -30°C is generally required. In contrast, for producing high molecular weight polyisobutene having a molar mass exceeding 100,000, a reaction temperature of -50°C or lower is required.

[0004] European Patent Application Publication No. 322241A2 discloses a process for producing polybutene having a molecular weight Mn of 500 to 5000 by reacting isobutene in the presence of BF3 under specific reaction conditions.

[0005] European Patent Application Publication No. 628575A1 and International Publication No. 2013 / 62763 pamphlet describe various reactors and the operation thereof for producing highly reactive polyisobutene.

[0006] None of the cited documents describes energy management in the reaction regime.

[0007] U.S. Patent No. 6,525,149,B1 describes the performance of ionic polymerization in a shell-and-tube reactor where the reaction mixture is circulated in a specific ratio relative to the monomer feed. The examples disclose specific flow rates and dimensions of the reaction chamber, but do not describe thermal control.

[0008] U.S. Patent Application Publication No. 2019 / 0118158A1 describes the performance of ionic polymerization, for example, polymerization from isobutene to polyisobutene, in a circulating heat exchanger reactor system (HERS), which comprises special channels in the form of parallelepipeds.

[0009] The drawback is that such reactor systems are complex to manufacture because the sides need to be welded. Welding is costly in terms of manufacturing, firstly, and secondly, it can cause leaks and corrosion.

[0010] German Patent Application Publication No. 102009019470A1 discloses the cationic polymerization of monomers in which at least the mixing of the flow and preferably the polymerization also takes place within a microstructure. The microstructure allows for a large heat exchanger surface area, which means that polymerization can take place substantially isothermally, but the microstructure has the disadvantage of rapidly clogging by polymer deposits. Therefore, since the reaction mixture carried out in the circuit contains polymers that cause microstructure deposition and blockage, according to German Patent Application Publication No. 102009019470A1, the reaction takes place only in a linear path without circulation.

[0011] Due to the low reaction temperature, these processes for producing polyisobutene are highly energy-intensive, particularly for generating and maintaining low temperatures and for removing the heat of reaction at low levels.

[0012] As a result of low reaction temperatures, when removing the heat of reaction in polymerization to polyisobutene, the use of inexpensive cooling media, especially water, particularly river water, is not usually an option. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] Therefore, the objective was to provide a process and apparatus for producing isobutene homopolymers and copolymers in which the energy intensity required for maintaining low temperatures is reduced and the energy efficiency of the apparatus is optimized. While isothermal reaction regimes may be desirable from a chemical standpoint, they are not economical.

[0014] While it is common to insulate cooled equipment and piping systems from ambient temperature, this insulation is not perfect. To ensure the operability and functionality of plant components that need to be movable or easily accessible, such as pumps or fittings, insulation materials penetrate at numerous points, forming thermal bridges. Such thermal bridges heat the contents of equipment, fittings, and piping at these locations, firstly reducing energy efficiency. Secondly, if the contents of the equipment and piping systems at these locations are still reactive due to the presence of inactivated Lewis acids, heating them above the desired reaction temperature further accelerates the reaction, which, as mentioned above, can lead to the formation of by-products or, in general, product heterogeneity, as the reaction temperature strongly influences the reaction, particularly the molar mass distribution, thereby increasing the polydispersity of the product. [Means for solving the problem]

[0015] The objective is a process for producing polyisobutene having a number-average molecular weight Mn of 500 to 1,000,000 from isobutene or an isobutene-containing monomer mixture, wherein the reaction is carried out in a reaction system. - Cooling surface area S 冷却 The ratio of the reaction volume V is given by the inequality. S 冷却 / V≧50m 2 / m 3 Preferably at least 55, more preferably at least 60, even more preferably at least 70, and especially at least 80 m 2 / m 3 in accordance with - Cooling surface area S 冷却and uncooled surface area S 非冷却 and the ratio satisfies the inequality S 冷却 / S 非冷却 ≧5 [m 2 / m 2 , preferably at least 7, more preferably at least 10, most preferably at least 12 [m 2 / m 2 , which is achieved by the process.

[0016] These criteria minimize the energy input into the reaction mixture via the surface of the reaction system.

[0017] A further advantage is that it is not necessary to keep the reaction temperature lower than required for the desired result of polymerization. Otherwise, the released polymerization energy must be removed at a lower temperature level, which will reduce the efficiency of the chiller for producing the cooling medium. Mode for Carrying Out the Invention

[0018] Definition In the context of the present specification, a reaction system means a part of a plant in which isobutylene or an isobutylene-containing monomer mixture reacts to obtain polyisobutylene as the number-average molecular weight Mn increases. In particular, in a plant, this includes reactors, heat exchangers, conduits, pumps, valves, fittings and flanges, preferably reactors, heat exchangers and conduits. This is preferably the part of the plant where isobutylene or the isobutylene-containing monomer mixture is in contact with at least one Lewis acid. The reaction is generally terminated by deactivating the at least one Lewis acid, for example by adding water or an alcohol, preferably water. Therefore, plant parts and devices that the reaction mixture contacts after deactivation of the Lewis acid are no longer included in the reaction system.

[0019] Therefore, more preferably, the reaction system means the part of the plant in which isobutene or an isobutene-containing monomer mixture is in contact with a non-inactivated Lewis acid, and the apparatus in which inactivation occurs as a result is no longer included in the reaction system. Therefore, most preferably, the reaction system includes a reactor, a heat exchanger, a pump, and a conduit leading from the reactor to the inlet of the apparatus in which inactivation occurs. Further means of terminating the reaction are, for example, the removal of monomer isobutene from the Lewis acid-containing reaction mixture by distillation or extraction, preferably by single-stage or multi-stage distillation. Complete conversion of monomer isobutene is also conceivable. In general, if there are no more reactive Lewis acids and monomer isobutene in contact with each other, the reaction no longer occurs.

[0020] The reaction system includes at least one portion, for example, one to three portions, preferably one or two portions, or more preferably one portion, in which the reaction mixture is in direct contact with a medium at a lower temperature than the reaction mixture via a thermally conductive surface, and at least one portion, for example, one to three portions, preferably one or two portions, or more preferably one portion, in which this does not apply.

[0021] The reaction mixture is circulated through at least one cooled heat exchanger. A fresh isobutene-containing feed is supplied to this circulating reaction mixture, and a corresponding amount of reaction product is removed to maintain a constant total volume of the reaction mixture.

[0022] To homogenize both the reaction mixture and the heat generated during the reaction, the volume of the circulating reaction mixture should preferably be at least 15 times, preferably at least 20 times, and more preferably at least 25 times, the fresh isobutene-containing feed.

[0023] Otherwise, the energy used to power the pump would make the entire process uneconomical, so the volume should not exceed 100 times, preferably 80 times, more preferably 70 times, even more preferably 60 times, and especially 50 times, the volume of the fresh isobutene-containing feed.

[0024] In addition, energy is introduced into the system via high pump power, which then needs to be cooled and removed from the reaction mixture. Therefore, large amounts of pump circulation hinder the optimization of energy efficiency.

[0025] Fresh isobutene-containing feed is generally mixed with the reaction mixture by energy input via shear energy. This can be done, for example, in a dynamic mixing apparatus, i.e., by a stirrer, or by pump circulation (natural or forced circulation), or by pump circulation using static mixing units such as a static mixer or nozzle in a pump circuit, by static mixing devices such as a static mixer, nozzle, baffle, Y-tube, or T-tube, or by dynamic mixing devices such as a mixing pump. Mixing is preferably carried out by a mixing zone having a static mixer or nozzle, preferably a static mixer.

[0026] The heat exchanger is selected from the group consisting of a temperature-controllable tubular reactor, a shell-and-tube heat exchanger, a plate heat exchanger, and a temperature-controllable tubular reactor having an interior, preferably a shell-and-tube heat exchanger and a plate heat exchanger, more preferably a shell-and-tube heat exchanger.

[0027] A possible but less desirable option is the performance in a cascade of at least one stirred-tank reactor or at least two stirred-tank reactors, preferably two to five, more preferably two to three, each cooled by a jacket and / or internal heat exchanger.

[0028] An advantage of the present invention is that it can be implemented in these conventional reactors and does not require the complex reactor system described in U.S. Patent Application Publication No. 2019 / 0118158A1.

[0029] Cooling surface area S 冷却This is the surface area of ​​all plant parts of the reaction system that are in direct contact with a medium that is colder than the reaction mixture in each plant part via a thermally conductive surface. The temperature difference between the colder medium and the reaction mixture is, for example, at least 5K, preferably at least 8K, more preferably at least 10K, and most preferably at least 12K.

[0030] Temperature differences greater than 30K between the cooler medium and the reaction mixture generally do not yield any benefit, and the temperature difference is preferably 25K or less, more preferably 20K or less, even more preferably 18K or less, and particularly 15K or less. Larger temperature differences lead to supercooling of the reaction mixture near the walls, where polyisobutene with a higher molar mass is produced. Furthermore, the decrease in temperature locally increases viscosity, making mixing more difficult and increasing residence time at the reactor walls. As a result, the average molar mass of polyisobutene becomes more heterogeneous, i.e., its polydispersity increases.

[0031] Lower temperature media may include, for example, brine, particularly glycol / water mixtures, or ammonia. Organic hydrocarbons, such as propane, butane isomer mixtures, or ethene, or partially or completely fluorinated hydrocarbons may also be used.

[0032] Thermally conductive surfaces include, for example, heat exchanger tubes or plates, or the surface of reactor jackets or tubes that carry lower temperature media.

[0033] S 冷却 This refers to the inside of the mentioned surface and any gas phase above it that is in direct thermal contact with the reaction mixture.

[0034] In contrast, the uncooled surface area S 非冷却This is the area of ​​all plant parts in the reaction system that are in direct thermal conduction contact with a medium having a higher temperature than the reaction mixture. In this specification, the interior of the mentioned surface is also considered. The medium having a higher temperature than the reaction mixture is preferably the ambient atmosphere under its respective dominant conditions. Each surface is generally thermally insulated from the outside, which nevertheless means that they have a higher temperature than the reaction mixture. Typical uncooled surfaces are pumps, fittings, valves, and pipes in particular, unless they are equipped with a jacket (trace cooling) that carries a cooler medium.

[0035] S 冷却 and S 非冷却 The limit setting and calculation of each surface area are achieved by considering the parts of the wall where the temperature is above the temperature of the reaction mixture.

[0036] The reaction volume V is the total volume of the reaction system surrounded by plant components in which isobutene or an isobutene-containing monomer mixture reacts with increasing number-average molar mass Mn. The preferred embodiments described above in the definition of the reaction system are also applicable accordingly in this specification.

[0037] Volume refers to the area enclosed by the surfaces defined above.

[0038] In the case of reaction volume, it may be useful to distinguish between conduits and containers.

[0039] In this specification, a conduit has a surface-to-volume ratio (S / V) of at least 4 m 2 / m 3 Preferably at least 8, more preferably at least, even more preferably at least 16, and especially at least 40 m 2 / m 3 These are defined as machines and devices having the following characteristics. In particular, these are piping systems having a nominal diameter (ND) of 100 mm to 1000 mm, preferably 300 to 500 mm.

[0040] For this purpose, it is irrelevant whether the surface is cooled or not.

[0041] For example, a piping system with an ND100mm filter length is approximately 40m. 2 / m 3 The S / V ratio is 16m for ND250mm. 2 / m 3 The S / V and ND1000mm are 4m 2 / m 3 It has an S / V ratio. The S / V ratio depends only on the radius r of the pipe: S / V = 2 / r.

[0042] In this specification, a container refers to a machine or apparatus whose surface area-to-volume ratio is smaller than that of a conduit as defined above.

[0043] Assuming the container is an ideal cylinder with a circular, flat bottom and top, a typical S / V ratio at radius r = 0.5m and height h = 1m is S / V = 6m 2 / m 3 Therefore, S / V is 4 at r=1m and h=1m, S / V is 8 at r=0.5m and h=0.5m, and S / V = 2.4m at r=1m and h=5m. 2 / m 3 Therefore, for such an ideal cylinder, the equation S / V = (2 × h + 2 × r) / (r × h) generally applies.

[0044] From these S / V ratios, 冷却 / V≧50m 2 / m 3 To achieve the ratio of the present invention, it is clear that the cooling of the conduit has a particularly significant influence, because, according to the above definition, the conduit has a high S / V ratio, that is, a large surface area where heat exchange takes place relative to its volume. Preferably, S 冷却 The ratio of / V is at least 55, more preferably at least 60, even more preferably at least 70, and especially at least 80 m 2 / m 3 That is the case.

[0045] 250m 2 / m3 S 冷却 The ratio of / V is preferably not exceeding the limit; more preferably S 冷却 The ratio of / V should be 200 or less, most preferably 175 or less, and especially 150 m. 2 / m 3 The following applies: High S 冷却 The / V ratio is essential for achieving an isothermal reaction, and it is not necessary for optimizing the energy efficiency of this invention.

[0046] According to the present invention, the ratio of uncooled surface area to cooled surface area is at least 5 [m²]. 2 / m 2 ], preferably at least 7, more preferably at least 10, most preferably at least 12 [m 2 / m 2 It must be ].

[0047] This makes it possible to limit the temperature rise of the uncooled reaction system to 2.5K or less, preferably 2.2K or less, more preferably 2.0K or less, and most preferably 1.8K or less, compared to the inlet temperature of the uncooled reaction system. This limitation of the temperature rise means that the temperature fluctuation of the reaction mixture is reduced, resulting in a heterogeneous product mixture.

[0048] On the other hand, the reaction does not need to be carried out isothermally, i.e., without a temperature rise. However, isothermal reactions would require a high cooling region. It has been found that a temperature rise of 0.3K or higher, preferably 0.5K or higher, more preferably 0.75K or higher, even more preferably 1.0K or higher, and especially 1.5K or higher, is acceptable for an uncooled reaction system without the product mixture becoming excessively heterogeneous.

[0049] This invention relates to at least the following plant components: - At least one apparatus for providing an isobutene-containing monomer mixture, selected from the group consisting of conduits, tanks, and buffer containers, - At least two storage containers for at least one Lewis acid and at least one co-catalyst, - An apparatus for measuring and supplying at least one Lewis acid and at least one co-catalyst to an isobutene-containing monomer mixture, - Cooling system, - At least one reaction system for converting an isobutene-containing monomer mixture, comprising at least one reactor, a heat exchanger, and a conduit, - At least one container for terminating the reaction by injecting water or alcohol, - At least one distillation apparatus for post-processing the reaction mixture, A manufacturing plant for producing polyisobutene containing, In the reaction system, the cooling surface area S 冷却 The ratio of the reaction volume V is given by the inequality. S 冷却 / V≧50m 2 / m 3 Preferably at least 55, more preferably at least 60, even more preferably at least 70, and especially at least 80 m 2 / m 3 in accordance with - Cooling surface area S 冷却 and uncooled surface area S 非冷却 The ratio is an inequality. S 冷却 / S 非冷却 ≥5[m 2 / m 2 ], preferably at least 7, more preferably at least 10, most preferably at least 12 [m 2 / m 2 We will further provide manufacturing plants in accordance with [ ].

[0050] The annotations made regarding the process are also applicable to the manufacturing plant of the present invention.

[0051] The present invention further provides the use of such a manufacturing plant for producing polyisobutene having a number average molecular mass Mn of 500 to 1,000,000 from isobutene or an isobutene-containing monomer mixture.

[0052] The present invention further provides a process for producing polyisobutene from an isobutene-containing monomer mixture in the presence of at least one Lewis acid in such a manufacturing plant.

[0053] In relation to this specification, polyisobutene means homopolymers and copolymers containing isobutene in a polymerized form.

[0054] For preparing such homo or copolymers containing copolymerized isobutene, a suitable isobutene source is, in a preferred embodiment, pure isobutene, or, in another preferred embodiment, isobutene-containing C4 hydrocarbon streams, such as C4 raffinate, particularly "raffinate 1", C4 cuts from isobutane dehydrogenation, from steam crackers, and C4 cuts from FCC crackers (fluid contact cracking), provided that the 1,3-butadiene present in these is substantially removed. C4 hydrocarbon streams from FCC purification units are also known as "b / b" streams. Further preferred isobutene-containing C4 hydrocarbon streams are, for example, product streams from propylene-isobutane co-oxidation, or product streams from metathesis units, which are generally used after conventional purification and / or concentration. Suitable C4 hydrocarbon streams generally contain less than 500 ppm, preferably less than 200 ppm, of butadiene. The presence of 1-butene and cis- and trans-2-butene is generally not significant. Typically, the isobutene concentration in the above C4 hydrocarbon stream is in the range of 40–60% by weight. For example, Raffinate 1 generally consists of essentially 30–50% by weight isobutene, 10–50% by weight 1-butene, 10–40% by weight cis and trans-2-butene, and 2–35% by weight butane. In the polymerization process of the present invention, the unbranched-chain butene of Raffinate 1 is generally substantially inert, and only isobutene is polymerized. In preferred embodiments, the monomer source used for polymerization is a C4 hydrocarbon stream having an isobutene content of 1%–100% by weight, particularly 1%–99% by weight, especially 1%–90% by weight, more preferably 30%–60% by weight, particularly a Raffinate 1 stream, a b / b stream from an FCC purification unit, a product stream from propylene-isobutane co-oxidation, or a product stream from a metathesis unit.

[0055] Preferably, the isobutene content in the C4 hydrocarbon stream is at least 40% by weight, and particularly preferably at least 45% by weight.

[0056] In particular, when raffinate stream 1 is used as the isobutene source, especially when polymerization takes place at temperatures of -20°C to +30°C, and especially 0°C to +20°C, it has been found useful to use water as the sole reaction initiator or as a further reaction initiator. However, at temperatures of -20°C to +30°C, specifically 0°C to +20°C, when raffinate stream 1 is used as the isobutene source, it is possible to omit the use of a reaction initiator.

[0057] The isobutene-containing monomer mixtures mentioned may contain small amounts of contaminants such as water, carboxylic acids, or mineral acids without causing a loss of critical yield or selectivity. It is useful to avoid the accumulation of these impurities by removing them from the isobutene-containing monomer mixtures, for example, by adsorption onto solid adsorbents such as activated carbon, molecular sieves, or ion exchangers.

[0058] The proportion of comonomers other than isobutene in polyisobutene is generally 10% by weight or less, preferably 7.5% by weight or less, more preferably 5% by weight or less, even more preferably 2.5% by weight or less, and particularly 1% by weight or less.

[0059] Using the process of the present invention, polyisobutene having a number-average molecular weight Mn of 500 to 1,000,000, preferably 500 to 250,000, more preferably 550 to 200,000, even more preferably 650 to 100,000, and particularly 750 to 50,000 g / mol can be produced.

[0060] Polydispersion, i.e., the quotient between weight-average MW and number-average molar mass Mn (PDI = M w / M n The PDI value is 1.05 to 3.5, preferably 1.05 to 2.5, particularly 1.05 to 2.0, and especially 1.1 to 1.85. A typical PDI value for optimal processing is 1.2 to 1.7.

[0061] The molar mass is determined by gel permeation chromatography using polystyrene as the standard.

[0062] Among these polyisobutenes, those having a high content of terminal ethylene double bonds (α-double bonds) are particularly preferred, especially those having a double bond content of at least 50 mol%, preferably at least 60 mol%, more preferably at least 70 mol%, even more preferably at least 80 mol%, and especially at least 90 mol%. These are referred to as highly reactive polyisobutenes, and the formation of terminal ethylene-unsaturated double bonds is particularly sensitive to any fluctuations in reaction temperature.

[0063] The process of the present invention is carried out at different reaction temperatures depending on the desired molar mass of polyisobutene.

[0064] In a preferred embodiment of the present invention, when the target is polyisobutene having a number-average molar mass Mn of 500 to 5000, the reaction temperature in the reaction mixture is preferably -5 to 25°C.

[0065] More preferably, the homo or copolymer is a highly reactive polyisobutene having a content of at least 70 mol%, preferably at least 80 mol%, and more preferably at least 90 mol% of terminal vinylidene groups.

[0066] In an alternative preferred embodiment of the present invention, when the target is a number-average molar mass Mn of 10,000 to 100,000, the reaction temperature in the reaction mixture is preferably -10 to -30°C.

[0067] In an alternative preferred embodiment of the present invention, when the target is a number-average molar mass of Mn of at least 150,000 to 1,000,000, the reaction temperature in the reaction mixture is preferably -50 to -90°C.

[0068] For example, the average residence time in a reaction system that is not mixed by recirculation, stirring, or backmixing should generally be less than 2 hours, preferably less than 90 minutes, and more preferably less than 60 minutes.

[0069] Polymerization is generally carried out at pressures of 700 mbar to 20 bar, particularly 1 bar to 10 bar, and especially 1.2 bar to 7 bar. High pressure is usually beneficial to the C4 hydrocarbon mixtures used and some inert diluents that may be used.

[0070] The polymerization reactor used in the process according to the present invention may, in principle, be any batch or continuous reactor type suitable for such liquid-phase polymerization, such as a stirred tank, a stirred tank cascade, a tubular reactor, or a loop reactor. If the polymerization by the process of the present invention is carried out above the boiling point of any inert diluent used and the monomer to be polymerized, this is preferably carried out in a pressure vessel, such as an autoclave or a pressure reaction vessel.

[0071] It is also important to stir the polymerizable compounds in the container, for example, by stirring, natural circulation, or pump (forced) circulation.

[0072] Polymerization by the process of the present invention may be carried out in the presence of an inert diluent. The inert diluent used must be able to reduce the increase in viscosity of the reaction solution that commonly occurs during polymerization to such an extent that the heat of reaction generated can be dissipated. Suitable diluents are solvents or mixtures of solvents that are inert to the reagents used. Suitable diluents include, for example, 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, particularly halogenated aliphatic hydrocarbons, such as methyl chloride, dichloromethane, trichloromethane (chloroform), 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane and 1-chlorobutane; halogenated aromatic hydrocarbons and alkyl aromatic compounds halogenated in the alkyl side chain, such as chlorobenzene, monofluoromethylbenzene, difluoromethylbenzene and trifluoromethylbenzene; and mixtures of the above-mentioned diluents. The diluent should be properly cleaned of impurities, such as water or mineral acids, before use, for example, by adsorption onto a solid adsorbent, such as activated carbon, molecular sieves, or ion exchangers. Naturally, the inert portion of the isobutene-containing C4 hydrocarbon mixture used as the starting material can also act as a diluent or as a component of the solvent mixture mentioned.

[0073] In preferred embodiments, no further diluents are added to the reaction mixture, which would increase the heat capacity of the reaction mixture and require cooling.

[0074] The reaction mixture may be single-phase or multi-phase, preferably single-phase. Typically, gaseous, liquid, and solid components exist side by side; the reaction mixture is preferably kept in liquid form, and liquid reaction mixtures may also contain solid components, such as polymers or Lewis acids.

[0075] Preferably, polymerization by the process of the present invention is carried out under mostly aprotic, and especially mostly anhydrous, reaction conditions. Mostly aprotic or mostly anhydrous reaction conditions mean that the water content (or content of protic impurities) in the reaction mixture is less than 50 ppm by weight, especially less than 5 ppm by weight. Therefore, generally, the raw materials are dried before use by physical and / or chemical means. In particular, it has been found useful to add organometallic compounds, such as organolithium, organomagnesium, or organoaluminum compounds, after conventional pre-purification and pre-drying, to aliphatic or alicyclic hydrocarbons used as diluents in an amount sufficient to remove most of the trace amounts of water from the solvent. The solvent thus treated is then preferably condensed directly into the reaction vessel. A similar procedure may be carried out for isobutene-containing C4 hydrocarbon mixtures. Drying with other conventional drying agents, such as molecular sieves, or pre-dried oxides, such as aluminum oxide, silicon dioxide, calcium oxide, or barium oxide is also preferable. In halogenated solvents where drying with metals such as sodium or potassium, or metal alkyls, is not an option, water or trace amounts of water are removed using a drying agent suitable for the purpose, such as calcium chloride, phosphorus pentoxide, or molecular sieves.

[0076] To stop the reaction, the reaction mixture is preferably inactivated by adding a sufficient amount of a protic compound, particularly water, alcohol, such as methanol, ethanol, n-propanol, and isopropanol, or a mixture thereof with water; or by adding an aqueous alkaline solution, such as an alkali metal or alkaline earth hydroxide such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide; an alkali metal or alkaline earth carbonate such as sodium carbonate, potassium carbonate, magnesium carbonate, or calcium carbonate; or an aqueous solution of an alkali metal or alkaline earth bicarbonate such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, or calcium bicarbonate.

[0077] The post-treatment of the reaction mixture includes at least one phase separation in which water, alcohol, or aqueous solution added to stop the reaction is separated from the organic phase of the reaction mixture. This may optionally be assisted by adding further water or aqueous solution to wash the reaction mixture.

[0078] Next, low-boiling point substances present in the reaction mixture are removed by distillation.

[0079] Low-boiling substances may include unconverted isobutene, unreacted components of the C4 hydrocarbon stream used as a starting material, and solvents. Smaller oligomers such as diisobutene and triisobutene are also separated.

[0080] Unconverted isobutene and smaller oligomers are preferably returned to the reaction, at least partially.

[0081] The removal of these low-boiling-point substances by distillation may be carried out discontinuously or preferably continuously in one or more steps, preferably one or two steps, more preferably two steps. Continuous distillation separation in at least two steps is preferred, the final step of which in each case is carried out under reduced pressure, for example, 10 mbar to standard pressure, preferably 20 to 900 mbar, more preferably 30 to 800 mbar, and at a temperature of 60 to 250°C, preferably 80 to 200°C, more preferably 100 to 190°C.

[0082] It will be apparent that distillation can also be carried out in a drip evaporator or a thin-film evaporator. For this purpose, the mixture is repeatedly passed through the apparatus in circulation, preferably under reduced pressure or standard pressure, for example, 10 mbar to standard pressure, preferably 20 to 900 mbar, more preferably 30 to 800 mbar, and at a temperature of 60 to 250°C, preferably 80 to 200°C, more preferably 100 to 190°C.

[0083] Advantageously, an inert gas, preferably argon or nitrogen-containing gas, more preferably argon, nitrogen, or a mixture of air and nitrogen (diluted air), most preferably nitrogen, is used, based on the volume of the liquid mixture, for example, 0.1 to 1, preferably 0.2 to 0.8, more preferably 0.3 to 0.7 m³. 3 / m 3 It can be introduced into the distillation apparatus of h.

[0084] In a particularly preferred modification, degassing may also be carried out in a container having an interior that facilitates degassing.

[0085] Possible devices for degassing are also paddle dryers having a cooling zone or, preferably, not having one, and optionally having a forced discharge device.

[0086] Such usable paddle dryers preferably do not have separation between heating and cooling zones to avoid causing abrupt temperature drops. Instead, the temperature of the residue increases as it passes through the apparatus, preferably by a temperature gradient that changes by only 50°C or less during the passage of the residue through the apparatus, and more preferably by no significant temperature change during the passage of the residue through the apparatus, i.e., the change is less than 20°C, particularly less than 10°C.

[0087] Such paddle dryers are essentially horizontal in structure, and the residue is generally transported through one or two mixing and kneading shafts inside the apparatus. In technical literature, these apparatuses are also called particle bed reactors, kneader dryers, or kneader reactors.

[0088] It is preferable that the paddle dryer is forcibly transported in the axial direction. Forced transport is achieved, for example, by the oblique position of the surface of the transport element.

[0089] Axial transport through the apparatus can preferably be carried out by an arrangement of transport elements, kneading elements and / or mixing elements, such as disc elements, shafts, screws, blades, wipers, or rotors.

[0090] It is particularly preferable that the residence time distribution within the paddle dryer is narrowed by separating the product conductive interior into various segments having baffle-like plates. More preferably, at least two plates are used.

[0091] Heating is carried out through the walls and can be done in any desired manner. Preferably, heating is carried out not only through the outer walls of the apparatus but also through internal components such as washing hooks, dividing plates and kneading shafts.

[0092] The thermal energy input to the reactor contents through the wall is typically greater than 120 kJ / kg for reactor contents and less than 2400 kJ / kg, preferably greater than 220 kJ / kg for reactor contents and less than 1800 kJ / kg, more preferably greater than 300 kJ / kg for reactor contents and less than 1400 kJ / kg, and most preferably greater than 360 kJ / kg for residue and less than 900 kJ / kg for reactor contents.

[0093] The distance over which the reaction mixture applied to the paddle dryer is heated is preferably more than 10% but less than 70% of the total length of the paddle dryer, more preferably more than 20% but less than 60% of the total length of the paddle dryer, and more preferably more than 30% but less than 50%.

[0094] A mechanical energy input of 5 W / kg or more in the apparatus is generally sufficient, preferably 10 W / kg or more, more preferably 20 or more, even more preferably 40 or more, particularly 80 or more, and especially 100 W / kg or more. Energy inputs exceeding 200 W / kg generally do not offer any advantages. The specific voltage inputs reported herein are voltage inputs per unit volume of the reaction mixture in the apparatus.

[0095] It is even more advantageous for the paddle dryer to have forced cleaning of at least 50%, preferably at least 60%, more preferably at least 70%, and in particular at least 80% of the inner surfaces that come into contact with the product. Forced cleaning is achieved by bringing the transport element closer to the outer wall, or by bringing the cleaning hooks closer to the transport element.

[0096] Such devices are available, for example, from List AG, Arisdorf, Switzerland, under the trademark names Discotherm® B or List-CRP or AP, and also from Bus-SMS-Canzler GmbH, Butzbach, Germany, under the trademark names Reasol® or Reactotherm®.

[0097] Optionally, a discharge means for forcibly discharging the reaction output, such as a screw, preferably a twin-screw, can be provided.

[0098] However, the mechanical transport means of the apparatus are usually sufficient to discharge the product from the apparatus.

[0099] A preferred Lewis acid is a boron halide, such as boron trichloride, boron trifluoride, or boron tribromide, preferably boron trifluoride.

[0100] The reactivity of boron halides is regulated with the help of one or more co-catalysts that form complexes with boron halides.

[0101] The co-catalysts used are preferably the following: C1- to C5-alkanols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, and tert-butanol. These alkanols are preferably used as a mixture of two alkanols, and preferably as a mixture of primary and secondary alcohols. 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. 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 methyl ether, bis(chloroethyl) ether, chloroethyl ethyl ether, tetrahydrofuran, or dioxane. Carboxylic acid esters having 2 to 20 carbon atoms, for example, C1-C4 alkylformates, C1-C4 alkylacetates, or C1-C4 alkylbutyrates.

[0102] The molar ratio of boron trihalide to total co-catalyst 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 co-catalyst can influence the establishment of the molecular weight of the isobutene homopolymer to be achieved, and thus contributes to the controlled adjustment of its molecular weight.

[0103] The amount of polymerization catalyst used is essentially determined by the type of co-catalyst and reaction conditions, particularly the reaction temperature and the desired molecular weight of the polymer. This can be determined based on several test runs for each reaction system. Generally, the polymerization catalyst is used in amounts of 0.0001% to 1% by weight, particularly 0.0005% to 0.5% by weight, and especially 0.001% to 0.1% by weight, based on the boron trihalide content in the catalyst complex and the isobutene used in each case.

[0104] In place of the preferred boron trihalide, the Lewis acid used may also be aluminum halide, C1-C4 alkylaluminum halide, C1-C4 alkoxyaluminum halide, C1-C4 alkoxyC1-C4 alkylaluminum halide, iron halide, gallium halide, titanium halide, zinc halide, tin dihalide, and tin tetrahalide. Of these, aluminum halide, C1-C4 alkylaluminum halide, iron halide, and titanium halide are preferred, aluminum halide and C1-C4 alkylaluminum halide are particularly preferred, and aluminum halide is especially very preferred.

[0105] Among the halides in the case of these latter Lewis acids, chlorides and bromides are preferred, with chlorides being particularly preferred.

[0106] The latter Lewis acids are also used in conjunction with the co-catalysts described above; the type and amount of co-catalysts are also applicable to these Lewis acids.

[0107] The advantages of the process of the present invention are that, because external heat input to the reaction mixture is reduced, the energy efficiency of the manufacturing process is improved, the released reaction heat can be removed at a higher temperature level, and as a result, the efficiency of the cooling system is improved and / or the amount of solvent or diluent used can be reduced.

[0108] Therefore, by improving energy efficiency, process energy consumption decreases, indirectly reducing emissions related to energy supply.

[0109] Accordingly, the present invention further provides a process for reducing emissions, particularly carbon dioxide emissions, which is preferably determined as a carbon footprint or life cycle assessment, more preferably in accordance with DIN EN ISO 14021, DIN EN ISO 14067, particularly version 2019-02 as specified herein, DIN EN ISO 14044, particularly version 2006+A1:2018 as specified herein, and / or DIN EN ISO 14040, particularly version 2009-11 as specified herein, wherein polyisobutene is produced by the process of the present invention.

[0110] Furthermore, the means of the present invention keep the reaction temperature more constant than without the means of the present invention. Without these means, a greater increase in the reaction temperature occurs in the reaction mixture, which, in particular, depends on the molecular weight of the polyisobutene formed at temperature, leading to an increase in the formation of higher molecular weight polyisobutene, i.e., an increase in the molar heterogeneity of polyisobutene, which is represented by a high degree of polydispersity. Therefore, the means of the present invention can reduce the degree of polydispersity of polyisobutene in the process. [Examples]

[0111] The reaction system for producing polyisobutene with a molar mass of 1000 g / mol consists of a loop reactor that can be divided into two sub-regions: a shell-and-tube heat exchanger having the following data and dimensions, in which the reaction medium (raffinate 1, isobutene content 46 wt%, supply temperature 4°C) is pumped through the loop using a pumping device, and the heat exchanger (cooled reaction volume) (reaction temperature as the starting temperature of the heat exchanger -15°C). On the outside of the tube, but on the inside of the shell-and-tube heat exchanger, a cooling medium (liquid ammonia at its boiling point) removes the heat of reaction. The inner surfaces of these heat exchanger tubes constitute the cooling surface.

[0112] The second part of the reaction system essentially consists of a loop necessary to maintain the movement of the reaction medium by a pump-type circulator, and thus to ensure maximum uniformity in the distribution of isobutene, the polymer formed, and the diluent. Simultaneously, heat transfer within the heat exchanger is facilitated by pumping the reaction medium in the desired manner. The surface of the loop is usually insulated, but is generally not cooled due to its design. Therefore, the inner surfaces of all piping systems and devices within the loop (e.g., the pump-type circulator) constitute uncooled surfaces.

[0113] The metric used to measure the efficiency of a shell-and-tube heat exchanger is the temperature drop across the entire heat exchanger, i.e., the difference between the outlet and inlet temperatures of the cooler. This is an indicator of the heat that should be removed from the uncooled reaction volume. The smaller the temperature drop, the more uniform the polymerization reaction temperature will be.

[0114] Example 1 In an energy-efficient embodiment of the present invention, the reactor and the cooled shell-and-tube heat exchanger are characterized by the following data.

[0115] [Table 1]

[0116] The uncooled loop of the reaction system is characterized by the following data.

[0117] [Table 2]

[0118] Ratio of cooling surface area to total volume: 204.5 m² 2 / 3.50m 3 = 58.4m 2 / m 3 Ratio of cooled surface area to uncooled surface area: 204.5 m² 2 / 28.75m 2 =7.11[m 2 / m 2 ] Overall temperature drop of the cooling unit: -1.9K

[0119] Example 2 In an energy-efficient embodiment of the present invention, the reactor and the cooled shell-and-tube heat exchanger are characterized by the following data.

[0120] [Table 3]

[0121] The uncooled loop of the reaction system is characterized by the following data.

[0122] [Table 4]

[0123] Ratio of cooling surface area to total volume: 588.1 m² 2 / 4.86m 3 =121.0[m 2 / m 3 ] Ratio of cooled surface area to uncooled surface area: 588.1 m² 2 / 42.85m 2 =13.7[m 2 / m 2 ] Overall temperature drop of the cooling unit: -1.3K

[0124] The temperature drop within the cooler is balanced by an equally high temperature increase due to the heat of reaction released in the uncooled portion of the reaction system, which is then removed within the cooler. Commercial S 冷却 / V or S 冷却 / S 非冷却 Increasing the coefficient of 5 reduces this rise in temperature within the reaction system, and thus the reaction system is subjected to smaller temperature fluctuations.

Claims

1. A method for producing polyisobutene having a number average molecular weight Mn of 500 to 1,000,000 from isobutene or an isobutene-containing monomer mixture, comprising carrying out the reaction in a reaction system, - Cooling surface area S 冷却 The ratio of the reaction volume V is given by the inequality. S 冷却 / V≧50m ２ / m ３ Preferably at least 55, more preferably at least 60, even more preferably at least 70, and especially at least 80 m ２ / m ３ in accordance with - Cooling surface area S 冷却 and uncooled surface area S 非冷却 The ratio is an inequality. S 冷却 / S 非冷却 ≧ 5 [m ２ / m ２ , preferably at least 7, more preferably at least 10 [m ２ / m ２ , most preferably according to at least 12, The reaction mixture is circulated through at least one cooling heat exchanger, and an isobutene-containing feed is supplied into this circulating reaction mixture, with a corresponding amount taken from the circuit. The heat exchanger is selected from the group consisting of a temperature-controllable tubular reactor, a shell-and-tube heat exchanger, a plate heat exchanger, and a temperature-controllable tubular reactor having an interior.

2. Cooling surface area S 冷却 S is the ratio of the reaction volume V. 冷却 / V is 250m ２ / m ３ The method according to claim 1, wherein the value does not exceed the value.

3. The method according to claim 1 or 2, wherein the isobutene-containing monomer mixture is pure isobutene.

4. The method according to claim 1 or 2, wherein the isobutene-containing monomer mixture is a C4 hydrocarbon flow containing not only isobutene but also 1-butene and cis- and trans-2-butene.

5. The above reaction involves boron halide, aluminum halide, and C １ --~C ４ - Alkyl aluminum halide, C １ --~C ４ - Alkoxyaluminum halide, C １ --~C ４ -Alkoxy-C １ --~C ４ - The method according to any one of claims 1 to 4, carried out in the presence of at least one Lewis acid selected from the group consisting of alkylaluminum halides, iron halides, gallium halides, titanium halides, zinc halides, tin dihalides, and tin tetrahalides.

6. In addition to the Lewis acid mentioned above, C １ --~C ５ The method according to claim 5, wherein at least one co-catalyst selected from the group consisting of 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 aforementioned cooling surface area S 冷却 The method according to any one of claims 1 to 6, wherein the cooling medium is in contact with the reaction mixture, the temperature difference from the reaction mixture being at least 5 K.

8. The aforementioned cooling surface area S 冷却 The method according to any one of claims 1 to 7, wherein the cooling medium is in contact with the reaction mixture, and the temperature difference from the reaction mixture is 30 K or less.

9. The method according to any one of claims 1 to 8, wherein the volume of the circulating reaction mixture is preferably at least 15 times and not exceeding 100 times the volume of the fresh isobutene-containing feed.

10. The method according to any one of claims 1 to 9, wherein the temperature rise of the uncooled reaction volume is 2.5 K or less, preferably 2.2 K or less, more preferably 2.0 K or less, and most preferably 1.8 K or less, compared to the inlet temperature to the uncooled reaction volume.

11. The method according to any one of claims 1 to 10, wherein the temperature rise in the uncooled reaction volume is 0.3 K or more.

12. A method for producing polyisobutene having a number average molecular weight Mn of 500 to 5000, according to any one of claims 1 to 11, wherein the reaction temperature in the reaction mixture is -5 to 25°C.

13. A method for producing polyisobutene having a number average molecular weight Mn of 10,000 to 100,000, according to any one of claims 1 to 9, wherein the reaction temperature in the reaction mixture is -10 to -30°C.

14. A method for producing polyisobutene according to any one of claims 1 to 9, wherein the reaction temperature in the reaction mixture is -50 to -90°C, and the polyisobutene has a number average molecular weight Mn of 150,000 to 1,000,000.

15. A method for reducing emissions, particularly carbon dioxide emissions, when producing polyisobutene having a number average molecular weight Mn of 500 to 1,000,000 from isobutene or an isobutene-containing monomer mixture, preferably determined as a carbon footprint or life cycle assessment, more preferably according to DIN EN ISO 14021, DIN EN ISO 14067, particularly version 2019-02 as specified herein, DIN EN ISO 14044, particularly version 2006+A1:2018 as specified herein, and / or DIN EN ISO 14040, particularly version 2009-11 as specified herein, the method comprising producing the polyisobutene by the method of any one of claims 1 to 11.

16. Use of a manufacturing plant for producing polyisobutene having a number average molecular weight Mn of 500 to 1,000,000 from isobutene or an isobutene-containing monomer mixture, wherein at least the following plant elements: - At least one apparatus for providing the isobutene-containing monomer mixture, selected from the group consisting of conduits, tanks, and buffer containers, - At least two storage containers for at least one Lewis acid and at least one co-catalyst, - An apparatus for measuring and supplying at least one Lewis acid and at least one co-catalyst to the isobutene-containing monomer mixture, - Cooling system, - At least one reaction system for converting the isobutene-containing monomer mixture, comprising at least one reactor, a heat exchanger, and a conduit, The heat exchanger is selected from the group consisting of a temperature-controllable tubular reactor, a shell-and-tube heat exchanger, a plate heat exchanger, and a temperature-controllable tubular reactor having an interior. The reaction mixture can be circulated through at least one cooling heat exchanger, in a reaction system, - At least one container for terminating the reaction by injecting water or alcohol, - At least one distillation apparatus for post-processing the reaction mixture, A manufacturing plant for producing polyisobutene containing, In the above reaction system, the cooling surface area S 冷却 The ratio of the reaction volume V is given by the inequality. S 冷却 / V≧50m ２ / m ３ Preferably at least 55, more preferably at least 60, even more preferably at least 70, and especially at least 80 m ２ / m ３ in accordance with - Cooling surface area S 冷却 and uncooled surface area S 非冷却 The ratio is an inequality. S 冷却 / S 非冷却 ≥ 5 [m ２ / m ２ ], preferably at least 7, more preferably at least 10, most preferably at least 12 [m ２ / m ２ ] Use of the manufacturing plant.

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