TW201105608A - Preparing of 3-methyl-1-butene - Google Patents

Abstract

The invention relates to a process for preparing 3-methyl-1-butene, in which a starting material containing 3-methyl-1-butanol is provided; in which the starting material is subjected to a catalytic dehydration to form a reaction product; where the reaction product contains at least the following components: 3-methyl-1-butene, di(3-methylbutyl) ether, water and unreacted 3-methyl-1-butanol; in which the reaction product is separated by distillation and removal of water into a low boiler fraction, a high boiler fraction and a water fraction; where the low boiler fraction contains 3-methyl-1-butene; where the high boiler fraction contains di(3-methylbutyl) ether and unreacted 3-methyl-1-butanol; where the water fraction contains essentially water; and in which the high boiler fraction is at least partly recirculated to the dehydration.

Description

201105608 VI. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a method for preparing 3-methyl-1-butene according to the first aspect of the patent application. [Prior Art] 3-Methyl-1-butene belongs to the group of methylbutenes, which are subgroups of rare hydrocarbons. 3-Methyl-1-butene is synonymous with 3-methylbutan-ene. 2Methyl-1-butene and 2-methyl-2-butene are likewise methylbutenes. The meaning of the word is similar. 3. Methyl-1-butene can be used as a monomer or co-monomer for the preparation of a polymer or copolymer. For the purposes of the present invention, 'a high boiling point compound' is a group component of a liquid mixture. The respective boiling points of the components are the boiling points of the residual components of the mixture or the vapor pressure of the components is lower than the residual components. The vapor pressure. "High-boiling compound" and "high-boiling component, are used synonymously. For the purposes of the present invention, "low-boiling compound" is a group component of a liquid mixture. The respective boiling points of the components are lower than the mixture. The boiling point of the residual component or the vapor pressure of the components is higher than the vapor pressure of the residual components. The inventors of the present invention conducted research from the closest prior art WO 2008/006633 A1. WO 2〇〇8/ 0〇663 3 A1 describes a process for preparing 201105608 3-methyl-1-butene from isobutene by three process steps. In this process, isobutene is first hydroformylated, and the hydroformylated product is 3-methyl. The butyraldehyde is hydrogenated to 3-methyl-1-butanol and then the water is removed from the resulting alcohol. Preferably, the alkali modified alumina is used to dehydrate the 3-methyl-1-butanol to a 3-methyl group. -1 - butene. In the dehydration reaction carried out in the gas phase at 3 40 ° C and 0.15 MPa described in the examples, the modification was carried out using 1.5% by weight of a ruthenium compound (calculated as ruthenium oxide). Γ-alumina is used as a catalyst. The product calculated on the basis of no water contains 94.5 % is 3-methyl-1-butene of the desired product, 3.2% by mass of 2-methyl-2-butene, 0.7% by mass of 2-methyl-1-butene, and 0.2% by mass ( 3-methylbutyl)ether, 0.5% by mass of high-boiling by-product, and 0.9% by mass of unreacted 3-methyl-1-butanol. Under the conversion of 99.2%, the yield was 92.2%, which was selected accordingly. 92.8%. The methyl butene fraction contains 96% of 3-methyl-1-butene and 4% of isomer. In the general method known from WO 2008/0063 3 3 ,1, water is optionally removed. Thereafter, the reaction mixture is separated into a starting alcohol (3-methyl-1-butanol), an olefin (3-methyl-1-butene, 2-methyl-2-butene, and 2-methyl group) by distillation. -1 -butene) and by-products (bis(3-methylbutyl)ether and high-boiling by-products). It is proposed that the unreacted alcohol be recycled to the dehydration reaction. The method discussed above can improve mass efficiency. (Yield) Therefore, the object of the present invention is to develop a method of the above type such that the method has a high mass efficiency. The achievement of this object is achieved not only by unreacted 3-methylbutanol but also by Recycling to dehydration Di(3-methylbutyl)ether. It was found that bis(3-methylbutyl)ether can be selectively re-dissociated into 3-methyl-1-butene and -6-201105608 3-methyl Butanol. Thus, by recycling bis(3-methylbutyl)ether to the dehydration reaction, the yield of 3-methyl-1-butene and thus the mass efficiency of the entire process can be increased. The invention thus provides a process for the preparation of 3-methyl-1-butene, a) wherein a starting material comprising 3-methyl-1-butanol is provided; b) wherein the starting material is subjected to a catalytic dehydration reaction to produce reaction product

Wherein the reaction product contains at least the following components: 3-methyl-1-butene, bis(3-methylbutyl)ether, water, and unreacted 3-methyl-1-butanol; d) Wherein the reaction product is separated by distillation and by phase separation (especially simple phase separation) to remove water to form a low boiling fraction, a high boiling fraction and a water fraction; e) wherein the low boiling fraction contains 3-methyl -1-butene; f) wherein the high boiling fraction contains at least bis(3-methylbutyl)ether and unreacted 3-methyl-1-butanol; g) wherein the water fraction contains water in nature; And h) wherein the high boiling fraction is at least partially recycled to the dehydration reaction. According to the present invention, the reaction product is separated into three fractions (i.e., a low boiling fraction (which contains the target product 3-methyl-1-butene) and a high boiling fraction (for a low boiling fraction (which contains the target product 3-methyl-1-butene) via two steps (distillation and removal of water). Recycled to the dehydration reaction 201105608) and the water fraction (process water to be discharged)): Here, the low boiling fraction can be first separated from the reaction product via distillation. The low boiling fraction containing the target product is then the overhead stream of the distillation. The bottom stream of the distillation is a mixture of two liquid phases (i.e., a high boiling fraction and a water fraction). This liquid/liquid mixture can then be separated by simple phase separation in the second step to separate the water from the high boiling point compound. Similarly, the reaction product may first be phase separated to separate the water fraction and then subjected to distillation in the second step. The low boiling fraction containing the target product is then the overhead stream of the distillation and the bottom stream of the distillation forms the high boiling fraction. If the high-boiling component which is a by-product of the dehydration reaction in the reactor and/or the high-boiling component in the starting material containing 3-methyl-1-butanol is present, it should be self-recycling. The loop removes the high boiling components to avoid accumulation of undesirably high concentrations and possibly also avoid product contamination. To remove the high boiling components, a relatively small portion of the high boiling fraction obtained by removing water can be discharged, for example, through the circuit. Alternatively, a second distillation is provided to thereby allow the high boiling component present in the starting material and/or in the dehydration reaction to be separated from the high boiling fraction and discharged. This optional distillation may be referred to hereinafter as the second distillation to make a difference in meaning; in contrast, the distillation described in the first time will hereinafter be referred to as the first distillation. The first "first" and "second" terms are not related to the technical aspects of the distillation. Thus, in a particular preferred variant of the method of the invention, the high is made in another process step The boiling point fraction is subjected to a second distillation to discharge a high boiling component 201105608. This produces a bottoms stream enriched in the boiling point component of the quotient. The bottom stream is discharged from the process. The overhead stream is primarily free of the high boiling component and can be subsequently Circulating to the dehydration reaction, it is advantageous to carry out the second distillation after mixing with the starting materials. Thus, the high boiling point compound present in the starting material can also be removed. Preferably, it is reacted with the dehydrating reaction. The second distillation is carried out at a pressure of at least 0.05 MPa. The top stream of the distillation can be subsequently recycled to the reactor without energy consumption compression. The second distillation is preferably in the distillation column. The top product of the distillation column is taken out in a gas form and fed to the dehydration reaction. As a result, at this point of the process, very little energy is lost. To further increase the energy efficiency of the process, 2nd The heat of condensation of the overhead product of the distillation can produce process steam. The process vapor can be used in the process itself or in another process operating adjacent to the process of the present invention. Advantageously, it is at least 0.05 MPa lower than the operating pressure of the dehydration reaction. The first distillation is carried out under pressure. Thus, no compression work is required for the process. The reaction product is preferably fed to the first distillation in a form of at least a portion of the gas. The process of the present invention preferably follows the process for preparing 3-methyl-1-butanol, wherein the process for preparing 3-methyl-1. butanol comprises distillation as a final process step, the top product of the distillation Containing 3-methyl-1-butanol, wherein the distillation of the method for preparing 3-methyl-butanol is carried out at a pressure higher than the operating pressure of the dehydration reaction by at least 0.05 MPa -9 - 201105608, and * The top product of the distillation of the process for the preparation of 3-methyl-1-butanol is taken out in a gas form and subsequently fed as a starting material to the dehydration reaction. Preparation of 3_methyl-丨_ The alcohol process is converted to a process for the preparation of 3-methyl-1-butene. Preferably, the water is removed by simple phase separation in a liquid-liquid separator. The distillations discussed herein are preferably each Fractionation Operation The present invention will be described by the following examples which are within the scope of the invention, and the scope of the invention is defined by the scope of the invention and the description of the invention, and is not limited to the embodiment. It is a part of the disclosure of the present invention. The scope of the following ranges, general formulas or compound types is intended to include not only the corresponding ranges or the groups of the compounds, but also For the purpose of the present invention, pure 3-methylbutanol or technical grade 3-methyl can be used in the method of the present invention. Butanol. The hydroformylated product formed by hydrogen hydroformylation and subsequent hydrogenation, in particular, gives 3-methylbutanol. 3-Methyl-1-butanol is isolated from the hydrogenation product mixture by distillation. 3-Methyl-1-butanol can be fed to the 3-methyl-1-butene plant in gaseous or liquid form. -10- 201105608 The 3-methyl-1-butanol plant and 3-methyl-1-butene plant can be used in one production location and the last process in the 3-methyl-1-butanol plant In the step, when 3-methyl-1-butanol is simultaneously obtained with the overhead product produced by distillation, it is advantageous to remove 3-methyl-1. butanol in the form of vapor from the distillation step and to Methyl-1·butanol was introduced into the 3-methylbut-1-ene plant as a vapor. Dehydration reaction: Dehydration of 3-methyl-1-butanol can be carried out in a gas/liquid mixed phase in which a solid catalyst is present or in a gas phase by means of a suspension catalyst or a particulate catalyst disposed on a fixed bed. . In the process of the present invention, the dehydration reaction is preferably carried out in the gas phase by means of a solid catalyst disposed on a fixed bed. Alkaline earth metals, oxides of aluminum, lanthanum, titanium, cerium, lanthanum and rare earth metals can be used as the catalyst. A combination of a plurality of oxides and a plurality of the above oxides may also be used. In the case where some catalyst (e.g., an alumina-based catalyst) is used, the acidity can be at a specific acidity by adding an alkali metal oxide. The catalyst and reaction conditions are preferably selected to greatly avoid the formation of by-products such as bis(3-methylbutyl)ether or high-boiling by-products and the resulting 3-methyl-1-butene ( For example, isomerization of 2-methyl-2-butene or 2-methyl-1-butene. Therefore, it is preferred to use a catalyst modified with an alkali metal oxide to carry out the dehydration reaction in the process of the present invention. The catalyst used may contain alumina (Al2?3) and/or chromium oxide (Zr?2) as a main component and an alkali metal and/or alkaline earth metal oxide. The other component which the catalyst may contain is titanium dioxide, cerium oxide and/or cerium oxide, and the amount of the other component is from 0.1 to 3% by mass, preferably from 0.5 to 5% by mass. The proportion of the basic metal oxide (calcium hydroxide calculated as oxide) in the catalyst is preferably 0.01 to 1% by mass, particularly preferably 0.1 to 5% by mass and excellently 0.1 to 3 by mass. %. Preferred alkali metal oxides are sodium oxide and/or potassium oxide. Preferred alkaline earth metal oxides are magnesium oxide and/or oxidized

I 钡. The gamma-alumina modified by cerium oxide (BaO), which is formed in the form of cerium oxide and aluminum oxide, is excellent as a catalyst for the dehydration reaction. Preferably, the BET surface area (as measured by nitrogen adsorption according to DIN 66131) is 80 to 3 50 m2/g (preferably 120 to 250 m2/g) of γ-alumina. The catalyst is produced by a conventional method. The conventional method is, for example, precipitating, impregnating or spraying an alumina body with a suitable salt solution and subsequently calcining. Preferably, the dehydration reaction is carried out using the catalyst described in WO 2008/006633 Α1 and WO 2005/080302 A1. In the method of the present invention, it is preferred to use a defined geometric shape and 0. 1 to 10 mm (preferably 0. Catalyst with a hydraulic diameter of 5 to 5 mm and particularly preferably 1·5 to 3 mm). The catalyst can be used in the method of the invention. The shaped body can take any shape. The catalyst used is preferably a shaped body in the form of a sphere, an extruded body, a cylinder or a nine. A particularly good system uses a spherical catalyst. The shaped bodies preferably have the hydraulic diameters described above. The dehydration reaction of 3-methyl-1-butanol using the above catalyst is preferably carried out at 200 to 500 ° C (preferably 240 to 360 ° C and particularly preferably 250 to 31 ° C). Implemented at temperature. The dehydration reaction can be carried out under reduced pressure, superatmospheric pressure (-12-201105608 superatmospheric pressure) or atmospheric pressure, and the reaction pressure is preferably 0. 1 to 15 MPa (absolute pressure) and more preferably 0. 1 5 to 0. 95 MPa (absolute pressure). The dehydration reaction is preferably carried out under the WHSV (weight-to-space velocity per hour) of 〇·〇1 to 30 h_1 (more preferably 〇·1 to 1 〇h-1) (kg 3-methyl-1- Butanol / kg catalyst / hour). All of the conversion of 3-methyl-1-butanol can be achieved in one operation using the preferred catalyst and under the preferred reaction conditions. However, in order to achieve extremely high selectivity to 3-methyl-1-butene, it has been found to be advantageous to achieve only partial conversion of the alcohol used in the attempt in one operation. The conversion of the 3-methyl-1-butanol in one operation is preferably from 50 to 95% and especially from 70 to 95%. Nonetheless, in the process of the present invention, 3-methyl-1-butanol can achieve nearly 100% conversion because the unreacted 3-methyl-1-butanol in the reactor is phase separated. It was separated from the target product 3-methyl-1-butene and recycled to the reactor. Here, the bis(3-methylbutyl)ether present in the dissociated product is recycled to the dissociation reactor in the same manner as 3-methyl-1-butanol. This is particularly advantageous for the catalyst system in which the bis(3-methylbutyl)ether is re-dissociated into 3-methyl-1-butanol and 3-methyl-1- at a temperature below 300 °C. Butene. The result of recycling the unreacted 3-methyl-1-butanol and its ether is the yield of 3-methyl-1-butene based on fresh 3-methyl-1-butanol. The system is between 85 and 99%, in particular between 95 and 98%. The dehydration reaction can be carried out using a conventional reactor (e.g., a tubular reactor 'shell tube reactor, a shaft furnace or a fluidized bed reactor or a combination thereof) -13-201105608. In the process of the present invention, the dehydration reaction is preferably carried out in a reactor equipped with a heating jacket and heated by a heat transfer liquid medium, and the dehydration reaction system is carried out such that the catalyst zone/reaction is relative to the inlet temperature. The temperature at any location in the zone is reduced below 50 ° C (preferably below 40 ° C and particularly preferably between 1 and 30 ° C) such that the reaction mixture in the reactor and the heat in the jacket The transfer medium flows in the same direction through the reactor such that the temperature difference between the temperature of the heat transfer medium at the inlet of the reactor and the temperature at the outlet of the reactor is less than 40 °C. The maximum temperature can be lowered by adjusting various parameters such as the temperature of the heat transfer medium for heating and the rate at which the heat transfer medium flows through the jacket. In particular, in the preferred system of the process steps of the dehydration reaction of the present invention, the inlet temperature of the gaseous starting material is preferably higher than 200 ° C, more preferably higher than 230 ° C and particularly preferably higher than 2 5 0 ° C. The inlet temperature of the starting material can be set at the front end of the reactor. When a new catalyst is used, the inlet temperature is preferably between 2 50 and 31 ° C. During operation, it is advantageous to increase the inlet temperature to 400 °C to increase catalyst deactivation, thereby maintaining the conversion. If the conversion cannot be maintained at 400 ° C, it is advantageous to replace all or part of the catalyst system. In addition to being too low in activity, the decrease in selectivity during operation may also be the reason for catalyst replacement. In particular, in a preferred system for the dehydration reaction of the process of the present invention, the reactor can be configured in any desired spatial orientation. If the reactor contains a plurality of reaction tubes, the reaction tubes can likewise assume any desired spatial orientation. However, the reactor is preferably arranged such that the reactor or the reaction tubes are vertically aligned. For a vertically aligned reactor, preferably the hot transfer medium is injected at or adjacent to the highest position of the jacket of the-14-201105608 and is discharged at or near the lowest position of the reactor. Transfer media, or vice versa. The reaction mixture in the reaction zone preferably flows in the same direction as the heat transfer medium in the jacket through the reactor. The heat transfer medium and the reaction mixture are particularly preferably flowed from the top down through the jacket of the reactor or the reaction zone of the reactor. Salt melt, water or heat transfer oil can be used as the heat transfer medium. For heat transfer oil systems in the temperature range of 200 to 40 (TC, which is advantageous for use with heat transfer oils, because of the lower capital cost of heating circuits using heat transfer oil compared to other technical solutions) For example, the trademarks sold on the market are Marlotherm (for example Marlotherm SH sold by Sasol Olefins & Surfactants GmbH), Diphyl (available from Bayer), Dowtherm (Dow sold) or Therminol (Therminol sold). The heat transfer oil is essentially a thermally stable cyclic hydrocarbon, preferably having a temperature between 10 and a higher 40 ° C (preferably 10 to 30 ° C). a heating jacket passing through the reactor at a temperature at which the starting material flows through the reactor. A temperature difference between the heat transfer liquid medium on the reactor (ie, an inlet temperature of the heat transfer medium entering the heating jacket and the temperature) The difference between the outlet temperatures of the heat transfer medium discharged from the heating jacket is preferably below 40 ° C, more preferably below 30 ° C and particularly preferably between 10 and 25 ° C. The temperature difference can be Passing the heating jacket per unit time The mass flow rate (in kilograms (kg) / hour (h)) of the heat transfer medium is adjusted. -15- 201105608 The preferred system for the dehydration reaction can be configured by heating the jacket and heating the liquid through the heat transfer liquid medium. All suitable reactors are implemented. The reactors have a reaction zone containing a catalyst (catalytic zone) that is isolated from the heating jacket and flows through the heating jacket. Preferably, the method is carried out by a plate reactor, a tubular reactor, a plurality of tubular reactors or a plate reactor connected in series, or a shell and tube reactor. The method of the present invention is preferably carried out by shell-and-tube reaction Or a plurality of shell-and-tube reactors connected in parallel. It may be noted that the hollow body in which the catalyst is located does not have to be a tube in the usual sense. The hollow body may also have a non-circular cross section. For example, elliptical or triangular. The material used to construct the reactor (especially the material separating the reaction zone from the heating jacket) preferably has a high thermal conductivity (greater than 40 W/mK). Preferably iron or An alloy such as steel is used as the material having a high heat transfer coefficient. If the method of the present invention is carried out using a shell and tube reactor, the length of each tube is preferably from 1 to 15 m, more preferably from 3 to 9 m. Preferably 4 to 9 m. In the process of the invention, the inner diameter of the individual tubes in the shell and tube reactor used is preferably from 1 〇 to 60 mm, more preferably from 15 to 40. Mm and particularly preferably from 20 to 35 mm. Advantageously, in the method of the invention, the wall thickness of the individual tubes in the shell and tube reactor used is preferably from 1 to 4 mm and more preferably Good ground 1 · 5 to 3 mm. In the shell and tube reactor used in the preferred system of the process of the invention, the tubes are preferably arranged parallel to one another. The tubes are preferably uniformly arranged. -16- 201105608 The tubes may be arranged, for example, in a square, triangular or diamond shape. The particularly preferred lines are arranged such that the imaginary lines connecting the points in the three adjacent tubes form an equilateral triangle, i.e., the tubes are equally spaced. The process of the present invention is preferably carried out using a shell and tube reactor wherein the tubes in the shell and tube reactor are spaced from each other by from 3 to 15 mm and particularly preferably from 4 to 7 m. The main reaction of the process of the present invention is the dehydration of 3-methyl-1-butanol to produce 3-methyl-1-butene and water. The reaction product at the lower end of the reactor preferably contains from 1 to 50% by mass, preferably from 5 to 30% by mass and particularly preferably from 5 to 20% by mass, depending on the 3-methyl-1-butanol conversion setting. The amount of 3-methyl-1-butanol. The amount of water of the reaction product is preferably from 8 to 20% by mass and more preferably from 12 to 18% by mass. The amount of the 3-methyl-1-butene of the reaction product is preferably 40 to 78% by mass and more preferably 5 5 to 74% by mass. Subsequent reactions may occur: dimethyl butyl ether is formed and trace amounts of high boiling components may also be formed, and the resulting 3-methyl-1-butene is isomerized to form 2-methyl-2-butene or 2-methyl-1-butene. The high-boiling fraction separated from the reaction product was recycled and the bis(3-methylbutyl)ether was also recycled to the reactor. . Under the preferred reaction conditions and the use of a preferred catalyst system, the bis(3-methylbutyl)ether is further dissociated into equal ratios of methylbutene and 3-methyl-1-butanol. Removal of water and first distillation: This dehydration reaction is followed by removal of water and first distillation. Here, the reaction product formed by the dehydration reaction is separated into a low-boiling fraction (which mainly contains methylbutenes) and a high-boiling fraction (which mainly contains a 3-methyl group which is not -17-201105608 reaction) by fractional distillation. 1-butanol and bis(methylbutyl)ether and possibly high-boiling components) and by liquid phase separation in a liquid-liquid separator produce a fraction mainly containing water. By complete condensation, the reaction product is separated into two liquid phases, wherein the light phase mainly contains the organic components methylbutene, 3-methyl-1-butanol and bis(methylbutyl)ether and possibly high The boiling point is an organic component, and the heavy phase mainly contains water. In this regard, the light and heavy refers to the specific density of the phase, ie the weight (water) has a greater density than the light (organic) phase. In order to separate the heavy (aqueous) phase from the light (organic) phase, a separator which can separate phases by gravity alone can be used. These gravity separators may also contain a chamber that acts as a coalescing promoter chamber to enhance separation efficiency. The use of these internals accelerates the process of coalescence and deposition. These structural chambers increase the capacity of existing plants or reduce the plant space of new plants. As the coalescing aid, for example, a plate type, a tumbling element type, a fiber entangled type or a fiber bed type separator can be used. The gravity separator can be configured as a horizontal or upright groove. Instead of a gravity separator, a separator for liquid-liquid separation according to the centrifugal principle can also be used. In this regard, the heavy phase is separated by a centrifugal force in the rotating tub. In the method of the present invention, in order to separate the heavy (aqueous) phase, it is preferred to use a gravity separator, more preferably a gravity separator having an internal horizontal tank, by liquid-liquid separation. The water is separated from the organic components below the physical solubility limit of the water. The solubility of methylbutene in water decreases with decreasing temperature and the solubility of water in methylbutene is also lowered by -18-201105608, so that the liquid-liquid separation should be as low as possible (more Preferably, it is carried out below 70 ° C, more preferably below 60 ° C and particularly preferably below 50 ° C. The pressure should be chosen such that no steam is produced; the pressure is preferably between 0. 3 to 2. 0 MPa (absolute pressure). Water may be separated from the reaction product formed by the dehydration reaction before or after the first distillation of the output product for the separation reactor, which is a low boiling point compound and a high boiling point compound. The advantage of separating prior to this first distillation is to reduce the stream to be treated by free water and thus the smaller stream will be treated. On the other hand, separating the water from the high-boiling compound stream after the first distillation can have an energy advantage because in this case the output product of the reactor can be completely or partially in gaseous form without cooling or complete condensation. Ground into the fractionation. In the first distillation, the reaction product is separated into a low boiling fraction and a high boiling fraction, the low boiling fraction mainly contains methylbutene and the high boiling fraction mainly contains unreacted 3-methyl-1- Butanol and bis(methylbutyl)ether and possible high boiling components. This separation is preferably carried out by using at least one tube (preferably and explicitly distillation column). Preferably, the distillation column used in the first distillation for fractionating the output product of the reactor into a low boiling point compound and a high boiling point compound preferably contains from 5 to 50 theoretical plates (more preferably 5 to 40 theoretical boards and particularly preferably 5 to 25 theoretical boards). The reflux ratio is preferably less than 5 and more preferably less than 0, depending on the number of theoretical plates achieved, the composition of the output product of the reactor, and the desired purity of the distillate and bottoms. 5. The operating pressure of the column can preferably be set to be between 0. 1 to 2. 0 MPa (absolute pressure). If the liquid is removed by liquid-liquid separation after the first -19-201105608 distillation, it is advantageous to feed all or part of the output product of the reactor in the form of a gas into the column. In this regard, to avoid the use of a compressor, it is advantageous to operate the column at a pressure below the operating pressure of the dehydration reactor. In order to condense 3-methyl-1-butene by cooling water, about 0. A pressure of 25 MPa (absolute pressure) is necessary. If for example 0. Dissociation at a pressure of 4 MPa (absolute pressure) is advantageously at 0. 3 to 0. The distillation column is operated at an operating pressure of 35 MPa (absolute). For example, steam or hot water can be used to heat the vaporizer. The high boiling fraction which has been separated preferably contains unreacted 3-methyl-1-butanol, bis(methylbutyl)ether and possibly a trace amount of a high boiling component formed by the reaction. The low boiling fraction preferably contains methylbutene having a purity of greater than 95% by mass based on the total overhead product. Here, the target product 3-methyl-1-butene and the isomers 2-methyl-2-butene and 2-methyl-1-butene and water are present in the low boiling fraction. The low boiling fraction obtained by fractional distillation and preferably comprising more than 95% by mass of methylbutenes can be directly sold as a product or can be recycled by further purification: during the recycling, it has been removed by removing water. The separated high boiling fraction is recycled to the dehydration reaction of the process of the invention. The high boiling fraction may be separately fed to the reaction zone or may be previously mixed with the starting material containing 3-methyl-1-butanol and subsequently fed to the reaction zone. Preferably, the high boiling fraction is mixed with the starting material -20-201105608 containing 3-methyl-1-butanol before being recycled to the reactor. According to the invention, the recycle stream contains unreacted 3-methylbutanol and bis(3-methylbutyl)ether. In the dehydration reaction, the selective dissociation of bis(3-methylbutyl)ether to 3-methyl-1-butene and 3-methylbutanol increases 3-methyl-1-butene. Yield and therefore mass efficiency of the total process. If the high boiling component of the secondary product is formed in the reactor for the dehydration reaction of the method of the present invention and/or the high boiling component is present in the starting material containing 3·methyl-1-butanol, The contour boiling components must be removed from the circuit prior to recycling to avoid accumulation of undesirably high concentrations and possibly also product contamination. In this regard, the boiling point of the high boiling component is higher than the boiling point of bis(3-methylbutyl)ether (i.e., the boiling point at atmospheric pressure is greater than about 1 75t). The high boiling fraction can be removed by, for example, discharging the small fraction ("scavenging stream") from the loop. However, to maintain this purge stream as small as possible, it is appropriate to utilize the high boiling fraction The second high-boiling compound is discharged by the second distillation. The process thus contains the first distillation and the second distillation. The bottom stream formed by the second distillation is rich in the high-boiling components and is discharged from the process. The top stream does not substantially contain the high-boiling components and can be recycled to the reaction. It can also be removed after the high-boiling fraction is mixed with the starting material 3-methyl-1-butanol. The second distillation of the high boiling component. In a particularly preferred variant of the process of the invention, the dehydration reaction is or may have been present in the starting material containing 3-methyl-1-butanol. The boiling point component is discharged by the second distillation of the fractionation of the high boiling fraction. This produces a bottoms stream enriched in the high boiling components. The bottom stream is discharged from the process from 21 to 201105608. The top stream is mostly Does not contain these high boiling components and Recycled. Preferably, the high boiling fraction recycled from the starting material 3-methyl-1-butanol in the distillation column discharges the high boiling components. The recycled high boiling fraction and the The starting materials are preferably introduced into the column at different sites. For this purpose, the distillation column used preferably contains from 5 to 50 theoretical plates (more preferably from 5 to 35 theoretical plates and is particularly preferred). 5 to 20 theoretical plates). Depending on the theoretical plate number achieved, the recycled high boiling fraction and the composition of the starting materials and the desired purity of the distillate and bottom product, the reflux ratio is preferably low. At 5 and better below 〇.  5. The operating pressure is preferably between 0. 1 to 2. 0 MPa (absolute pressure). When the dehydration reaction of the overhead product is carried out under superatmospheric pressure and in the gas phase, it is advantageous that the distillation can be carried out at a relatively high pressure; for this, the top condenser is preferably operated as a partial condenser. And the top product is removed as steam. If the reaction pressure in the dissociation reactor is, for example, 0. 4 MPa (absolute pressure), the distillation pressure of the second distillation should preferably be at least 〇45 MPa (absolute pressure). More than 〇. At an operating pressure of 15 MPa (absolute pressure), low pressure steam can be generated by the heat of condensation and the low pressure steam can be used to heat other columns of the process. Depending on the operating pressure selected, steam or heat transfer oil may be used to heat the column. The bottom product may contain the high boiling components to be separated and 3-methyl-1-butanol and bis(3-methylbutyl)ether. This mixture can be used thermally, as a starting material for a synthesis gas plant or possibly as a solvent or fuel additive. If the method of the present invention uses a plurality of columns (e.g., columns designated K1-22-201105608 and K2 in Figures 1 through 4), such columns may contain internals such as plates, rotating random beds, and/or stages. Filling up. For trays, for example, the following types can be used: - a plurality of plates containing a plurality of holes or slits in the bottom plate; - a plurality of chimneys covered by a plurality of bell-shaped bodies, covers or exhaust hoods a plate; - a plurality of plates covered by a plurality of movable valves in the bottom plate; - a plurality of plates having a special configuration. In a column containing a rotating inner portion, the reverse flow can be sprayed, for example, by a rotating funnel or by a rotor to spray the backflow into the heating tube to form a film. As previously stated, the method of the present invention can use a bed of random beds having a variety of different components. The charging elements may comprise substantially (especially steel, stainless steel, copper, carbon, ceramics, porcelain, plastics) and have a wide variety of shapes (especially spheres, rings containing a profiled surface, containing an internal network) Or through the ring of the wall opening, the shape of the wire mesh and the shape of the spiral). Fillers having irregular/ordered geometries may comprise, for example, or a mesh. Examples of such fillings are metal or plastic; Sulzer mesh filling BX, Sulzer thin Mellapak made of sheet metal, high-efficiency filling from Sulzer (eg pakPlus), purchased from Sulzer Structured fillings (Optiflow), (BSH) and Ktthni (Rombopak). The inner, neck or perforated spray is inversely filled with a material glass or a smooth or ring-shaped sheet made of a saddle metal plate. Mella-Montz -23- 201105608 FIG. 1 shows a method in which the method of the present invention can be carried out. A block diagram of a first preferred system of the inventive plant. The feed stream (1) containing 3-methyl-1-butanol is mixed with the recycle stream (7b) and is mainly converted into methylbutenes and water by a dehydration reaction in the reactor R1. The bis(3-methylbutyl)ether present in the recycle stream (7b) is converted to an equal proportion of methylbutenes and 3-methyl-1-butanol. In this plant, after the reaction product (4) obtained by the dehydration reaction in the reactor R1 is completely condensed, most of the water is first separated from the reaction product (4) by separating the liquid/liquid into the separator D1. . Here, the heavy (aqueous) phase (5) is discharged and the light (organic) phase (4a) is fed to the column K2. The water is separated below its physical solubility. In the column K2, most of the non-aqueous reactor output product is separated into a low boiling fraction of the top product (6) and a high boiling fraction of the bottom product (7), the low boiling fraction mainly containing the reaction formed by the reaction. The butenes and the high boiling fractions contain at least unreacted 3-methyl-1-butanol and the bis(3-methylbutyl)ether formed by the reaction and possibly high boiling components. The bottom product (7) produced by this distillation is recycled to the reactor R1. The streams (1) and (7) can optionally be introduced to the reactor R1 individually or together. If the high boiling component of the by-product formed in the reactor R1 or the high-boiling component is present in the starting material (1) containing 3-methyl-1-butanol, the high-boiling components may be freely The ground is discharged with the flow (8) to avoid accumulation of undesirably high concentrations and possibly also to avoid contamination of the product. In Figure 1, the separated aqueous phase (5) can be optionally distilled to reduce the mass of organic matter and the distillate comprising water and low boiling compounds can be recycled to the separator D1 » • 24 · 201105608 Figure 2 shows that it can be implemented A block diagram of a second preferred embodiment of the plant of the present invention in accordance with the method of the present invention. The preferred system of Figure 2 differs from the preferred system of Figure 1 in that the water system formed by the dehydration reaction of 3-methyl-1-butanol is only after the low-boiling fraction (6) has been separated. The high boiling fraction (7) at the lower end of column K2 is removed. Here, most of the water is separated again by the liquid-liquid separation in the separator D1. The heavy (aqueous) phase (5) is discharged and the light (organic) phase (7a) is recycled to the reactor R1 » the water is again separated below its physical solubility. After fractionation in the column K2, the water removed from the high-boiling compound stream (7) therefore has an energy advantage' because the reactor output product (4) can be cooled or completely condensed in this case. The gas phase form is introduced completely or partially into the sub-saturated column K2. If the high-boiling component which is formed as a by-product in the reactor R1 and/or the high-boiling component is present in the starting material (1) containing 3-methyl-1-butanol, these high-boiling components It can be discharged again with the flow (8). Figure 3 is a block diagram showing a third preferred embodiment of the plant of the present invention in which the method of the present invention can be practiced. The preferred system of Figure 3 differs from the preferred system of Figure 2 in that the dehydration reaction in the reactor R1 by the process of the present invention is formed as a by-product and/or is present in the 3-methyl-anthracene-butanol-containing The high boiling component which is a secondary component in the starting material is discharged. In Fig. 3, the discharge of high-boiling components can be achieved by dividing the majority of the non-aqueous circulating stream (7a) in the column K1. Here, the recycle stream (7a) is separated into a top stream (7b) and a bottom stream (3). The top stream (7b) is largely free of high boiling components. The bottom stream (3) contains a rich amount of high boiling components and bis(3-methylbutyl)ether and 3-methyl-butanol. This overhead stream (7b) from the column K1 is recycled to the dehydration reactor R1 from -25 to 201105608. Figure 4 is a block diagram showing a fourth preferred embodiment of the plant of the present invention in which the method of the present invention can be practiced. The preferred system of Figure 4 differs from the preferred system of Figure 3 in that the reactor R1 is formed as a by-product and/or is present in the starting material containing 3-methyl-1-butanol as a secondary The high boiling component of the component is discharged via the bottom stream (3) of column K1. Here, the starting material (1) and the recycle stream (7a) are fed to the column K1. Within the column K1, the streams are separated into a top stream (2) and a bottom stream (3), the top stream (2) being largely free of high boiling components. The bottom stream (3) contains a rich amount of high boiling components and bis(3·methylbutyl)ether and 3·methyl-1-butanol. This overhead stream (2) from the column K1 is recycled to the reactor R1. Here, the column K1 is preferably operated at an operating pressure higher than the operating pressure of the reactor R1. In this case, the top condenser of the column K1 is preferably operated as a partial condenser. The top product (2) in the form of a vapor is removed and fed to the reactor R1. The following examples illustrate the invention without limiting the scope of the invention, and the scope of the invention is defined by the invention and the scope of the patent application. Defined. [Examples] Example 1: The dissociation of 3-methyl-1-butanol was carried out in an electrically heated, downstream fixed bed reactor to a purity of 99. 8 1% by mass of 3-methyl-1-butanol is spherical (1. 7 to 2. B44/1C catalyst reaction of 1 mm sphere), the bulk density of the catalyst is 0. 58 g/cm3. The catalyst is 0. 48% yttria-modified gamma-alumina catalyst and the production of the catalyst is described in the patent application filed on the same date by the same applicant. The liquid starting material was completely vaporized at 23 ° C in the front end vaporizer before entering the reactor. In the gas phase of 3-methyl-1-butanol at a reaction temperature of between 280 and 300 ° C (18. 5 g / h) through the catalyst (29. 0 g), that is, the hourly weight space velocity (WHSV) is 0. 64 h·1. The WHS V represents g starter / g catalyst / hour. Reaction pressure system 15 MPa (absolute pressure). The gaseous product is cooled by a condenser and collected through a steel collector. The output product has the composition shown in Table 1 on the basis of no water content. Reactor temperature rc] 280 290 300 WHSV [h·, 0. 64 0. 64 0. 64 Composition Mass % Mass % Mass % 3-methyl-1-butene 63. 49 85. 07 89. 73 2-methyl-1-butene 0. 24 0. 87 2. 08 2-methyl-2-butene 1. 46 3. 77 7. 54 3-methyl-2-butanol 0. 01 0. 00 0. 00 3-methyl-1-butanol 15. 56 5. 90 0. 29 bis(3-methylbutyl)ether 18. 86 4. 12 0. 04 Residue / high boiling point compound 0. 38 0. 27 0. 32 methylbutene isomer (normalized) 3-methyl-1-butene [%] 97. 39 94. 83 90. 32 2-methyl-1-butene [%] 0. 37 0. 88 2. 09 2-methyl-2-butene [%] 2. 24 3. 79 7. 59 Table 1: Example 1 Reactor output using a B44/lc catalyst for dehydration reaction Composition of the product Table 1 shows the composition of the product and the distribution of methylated butenes normalized to 1% by weight. It can be found that the formation of the desired product 3-methyl-1-butene increases with the increase of anti--27-201105608. The main intermediate/by-product formed by the dissociation reaction of 3-methyl-1-butanol ether (i.e., bis(3-methylbutyl)ether) 3-methyl-1-butanol. When the temperature is raised from 280 ° C to 290 ° C or 300 ° C, the proportion of 3-methyl-1-butene in the isomer mixture is lowered as a result of the isomerization. At the reaction temperature of 280 °C, the highest proportion of 3-methyl-1-butane (about 9 7 · 4 %) is formed: however, under these reaction conditions, a little bis (3-methyl butyl) is formed. The acid is such that, in the absence of recycling of the acid, the yield of 3-methyl-1-butane produced by a single pass is not satisfactory. Example 2: Dissociation of bis(3-methylbutyl)ether as shown in Example 1, which was formed in the middle of the reaction of 3-methyl-1-butanol dissociated into 3-methyl-1-butene. Bis(3-methylbutyl)ether of the body and by-products. In Example 2, the dissociation reaction of bis(3-methylbutyl)ether was carried out using the same catalyst as used in Example 1. In a co-current fixed bed reactor heated by electricity, the purity is 99. 63% by mass of bis(3-methylbutyl)ether was subjected to the same catalyst reaction as used in Example 1. The liquid starting material was completely vaporized at 230 °C in the front end evaporator prior to entering the reactor. For a reaction temperature between 270 and 300 ° C and 0. At a reaction pressure of 15 MPa (absolute pressure), the gas phase of bis(3-methylbutyl) ether (18. 5 g / h) through the catalyst (29. 0 g), which corresponds to WHSV is 0. 64 1Γ1. The gaseous product is cooled by a condenser and collected through a steel collector. The output product had the composition shown in Table 2 by GC analysis and calculated on the basis of no water. Meanwhile, in addition to the composition of the product, the distribution of methylene butene isomers which were normalized to 100% is also shown in Table 2. -28- 201105608 Reactor temperature [°c] 270 280 290 300 WHSV [h''l 0. 64 0. 64 0. 64 0. 64 Composition Mass % Mass % Mass % Mass % 3-methyl-1-butene 54. 22 79. 09 91. 67 93. 64 2-methyl-1-butene 0. 19 0. 46 0. 62 1. 16 2-methyl-2-butene 0. 91 1. 80 2. 75 4. 54 3-methyl-2-butanol 0. 06 0. 05 0. 04 0. 02 3-methyl-1-butanol 7. 65 5. 46 2. 31 0. 36 bis(3-methylbutyl)ether 36. 65 12. 89 2. 34 0. 08 Residue / high boiling point compound 0. 32 0. 25 0. 27 0. 20 methylbutene isomer (normalized) 3-methyl-1-butene [%] 98. 01 97. 22 96. 45 94. 26 2-methyl-1-butene [%] 0. 34 0. 57 0. 65 1. 17 2-methyl-2-butene [%] 1. 64 2. 21 2. 89 4. 57 Table 2: Example 2 The composition of the reactor output product of the dissociation reaction of bis(3-methylbutyl)ether using B44/lc catalyst is shown in Table 2, bis(3-methylbutyl)ether It is selectively converted to 3-methyl-1-butene. Similarly, the second product of the ether dissociation reaction (i.e., 3-methyl-1-butanol) is also converted to 3-methyl-indole-butene. The conversion system increased with time; substantial quantitative conversion of bis(3-methylbutyl) acid was achieved at 300 °C. However, the proportion of the desired product 3-methyl-1-butene in the mixture of isomers decreases with increasing temperature. Example 3: Dissociation reaction of 3-methyl-1-butanol/bis(3-methylbutyl)ether mixture The starting material used in Example 1 (substantially pure 3·methyl-1-butanol) -29- 201105608 The starting material used in Example 2 (substantially pure bis(3-methylbutyl)ether) is mixed in proportion to form a bis (3-methyl butyl group) containing about 30,0% by mass. Base) ether and about 70. 0% by mass of a mixture of 3-methyl-1-butanol. The mixture was subjected to the same catalyst reaction as used in Examples 1 and 2 in an electrically heated, downstream fixed bed reactor. The liquid starting material was completely vaporized at 23 ° C in the front end vaporizer before entering the reactor. In the reaction temperature of 280 to 300 ° C, the gas phase of 3-methyl-1-butanol (18. 5 g / h ) through the catalyst (29. 0 g), which corresponds to a WHSV of 0. 64 h·1. The output product had the composition shown in Table 3 by GC analysis and calculated on the basis of no water. Meanwhile, the distribution of methylene butene isomers which were normalized to 100% is also shown in Table 3. Reactor temperature [°c] 280 290 300 WHSV rh-'l 0. 64 0. 64 0. 64 Composition Mass % Mass % Mass % 3-methyl-1-butene 56. 77 76. 19 91. 28 2-methyl-1-butene 0. 25 0. 71 1. 61 2-methyl-2-butene 1. 28 2. 91 6. 24 3-methyl-2-butanol 0. 02 0. 01 0. 00 3-methyl-1-butanol 18. 26 9. 26 0. 47 bis(3-methylbutyl)ether 23. 10 10. 61 0. 13 Residue / high boiling point compound 0. 32 0. 31 0. 27 methylbutene isomer (normalized) 3-methyl-1-butene [%] 97. 38 95. 46 92. 08 2-methyl-1-butene [%] 0. 43 0. 89 1. 62 2-methyl-2-butene [%] 2. 20 3. 65 6. 29 Table 3: Composition of reactor output product of Example 3 using a B4 4/lc catalyst for the dissociation reaction of a mixture of 3-methyl-1-butanol/bis(3-methylbutyl)ether -30- 201105608 As shown in Table 3, bis(3-methylbutyl)ether was selectively converted to the desired product 3-methyl-1-butene at a reaction temperature of, for example, a low temperature of 28 °C. At this temperature, the ether content of the product was about 23% by mass, which was the same size as in Example 1 using pure 3-methyl-1-butanol as a starting material (at 280 ° C). About 19% by mass). As the reaction temperature increases, the ether content of the product decreases; at 300 ° C, the ether is substantially completely reacted. However, as the temperature increases, the proportion of 3-methyl-1-butene in the isomer mixture decreases simultaneously. At a reaction temperature of 280 ° C, the highest ratio of 3-methyl-1-butene is about 97%. Thus, an amount of substantially the same target product in the mixture of the isomers is achieved (e.g., Example 1 using pure 3-methyl-1-butanol as the starting material (about 97% by mass at 280 ° C) )). By way of such experimental examples, it can be shown that when the reaction is carried out at a relatively low reaction temperature of less than 3 ° C, in principle, the target product (ie, 3-methyl-1-butene) can be increased. The proportion of the C5 isomer mixture. When unreacted 3-methyl-1-butanol and the resulting bis(3-methylbutyl)ether are separated and recycled, the total conversion and the corresponding yield can be increased to a very high level, because even At relatively low reaction temperatures below 300 ° C, the ether can be converted to the target product with high conversion and selectivity. Therefore, it can be shown that the method of the present invention, in which not only unreacted 3-methyl-1-butanol and bis(3-methylbutyl)ether are recycled back to the dehydration reaction, is superior in mass efficiency. Another method (where only unreacted alcohol is recycled). In addition to the reported experimental results, the process of the present invention will be illustrated by the calculation of the total process including the distillation step and the recycle as described in -31 - 201105608. By the steady state simulation program ASPEN Plus (AspenTech 2006. 1 version) Perform these calculations. To produce transparent and reproducible data, only commonly available material data is used. Use the property method "UN IF AC-DM D" (see J.  Gmehling, J.  Li, and M.  Schiller, Ind.  Eng.  Chem.  Res.  32, (1 993), pp.  1 78- 1 93 ) as a material data model. Therefore, those skilled in the art can easily understand such calculations. For each of the reactors R1, the simulated reactor volume is 37. 5 m3, and it is assumed that the reactor R1 contains the catalyst bed as used in Examples 1 to 3. To simulate the reactor, calculations were performed using a kinetic reactor model based on a wide range of test data for the catalyst. Thus, for each case, the assumed reaction temperatures simulating the reactor are also recited in these examples. Since each case also states the composition of the influent and effluent streams of the reaction step, those skilled in the art will repeat the embodiment by replicating a reactor having a predetermined conversion when an exact equation of the kinetics is unknown. Calculation. Example 4: Method for preparing 3-methyl-1-butene as shown in Figure 1 Example 4 corresponds to the non-inventive variant shown in Figure 1. As shown in Figure 1, it is assumed that the feed stream (1) contains a stream of pure 3-methyl-1-butanol (10 t/h). Stream (1) is mixed with the recycle stream (7b). The recycle stream (7b) is a stream formed by the bottom of the column K2 after being separated from the purge stream (8). The composition of the starting material (1), the composition of the recycle stream (7b), and the composition of the feed stream (2) fed to the reactor R1 by mixing are shown in Table 4. The feed stream contained about 16% by mass of bis(3-methylbutyl)ether and 82% by mass of 3-methyl-1-butanol under the process conditions selected from -32 to 201105608. Name Feed stream Circulating flow Reactor feed mass flow [kg/h] 10000. 00 5227. 53 15227. 53 mass ratio [kg/kgj water 〇. 〇〇〇〇〇〇 0. 001149 0. 000395 3-methyl-1-butene 〇. 〇〇〇〇〇〇 0. 002414 0. 000829 2-methyl-1-butene 〇. 〇〇〇〇〇〇 0. 000030 (λ (8) 0010 2-methyl-2-butene 〇. 〇〇〇〇〇〇 0. 000500 0. 000172 3-methyl-1-butanol 1. 000000 0. 486061 0. 823568 bis(3-methylbutyl)ether 〇. 〇〇〇〇〇〇 0. 473635 0. 162597 high boiling point compound 〇. 〇〇〇〇〇〇 0. 036209 0. 012430 4 : The composition of the starting material (1), the composition of the recycle stream (7b) and the composition of the reactor feed (2) exemplified in Example 4, the stream (2) is heated by vaporization to the reaction temperature and in the form of steam. Feed to the reactor R1. The reactor was at 275 ° C and 0. Operate at 40 MPa (absolute pressure). Under these reaction conditions, the conversion of 3-methyl-1-butanol was about 78%. The composition of the reactor output (4) is shown in Table 5. The bis(3-methylbutyl) acid and the sulphur boiling point compound by-product formed by separation from 3-methyl-1-butene and the isomer thereof. The c丨5-hydrocarbon-based high-boiling compound which is a subsequent product of 3-methyl-1-butanol is assumed by the example. It should be noted that the reaction occurring in the stream (2) bis(3-methylbutyl) ether also occurs simultaneously. The bis(3-methylbutyl)ether is dissociated into equal proportions of 3-methyl-1-butene and 3-methyl-1-butanol, resulting in one of the reactor outputs (4) ( The content of 3-methylbutyl) acid is only moderately increased to about I? mass% -33- 201105608 Number shown in Figure 1 (4) (4a) (5) Name reactor output organic phase D1 aqueous phase D1 Mass flow [kg/h] 15227. 53 13363. 17 1864. 36 mass ratio [kg/kg] water 0. 131318 0. 014143 0. 971193 3-methyl-1-butene 0. 494342 0. 561625 0. 012074 2-methyl-1-butene 0. 001648 0. 001874 0. 000029 2-methyl-2-butene 0. 010263 0. 011676 0. 000134 3-methyl-1-butanol 0. 178190 0. 200738 0. 016565 bis(3-methylbutyl)ether 0. 171155 0. 195033 0. 000004 high boiling point compound 013085 0. 014910 〇. 5 Table 5: The composition of the reactor output (4) exemplified in Example 4 and the composition of the organic phase (4a) and the aqueous phase (5) from the liquid-liquid separator D1. The material (4) was completely condensed and cooled to 45 ° C and fed to the liquid-liquid separator D 1 . Within the separator D1, the water system is separated below its physical solubility limit and discharged in heavy phase (5). Subsequently, most of the non-aqueous stream (4a) is introduced into the distillation column K2. The mass flow and composition of the organic phase (4a) and the aqueous phase (5) are shown in Table 5. -34- 201105608 Number shown in Figure 1 (6) (7) (8) Name Κ2 distillate Κ2 bottom product purge stream mass flow [_ 7860. 49 5502. 68 275. 15 mass ratio 1 [kg/kg] water 0. 023239 0. 001149 0. 001149 3-methyl-1-butene 0. 953097 0. 002414 0. 002414 2-methyl small butene 0. 003165 0. 000030 0. 000030 2-methyl-2-butene 0. 019499 0. 000500 0. 000500 3-methyl·1-butanol 0. 001000 0. 486061 0. 486061 bis(3-methylbutyl)ether 〇. 〇〇〇〇〇〇 0. 473635 0. 473635 high boiling point compound 〇. 〇〇〇〇〇〇 0. 036209 0. 036209 Table 6: Composition of the distillate (6) and bottom product (7) and the composition of the purge stream (8) of the column K2 exemplified in Example 4 The organic phase (4a) was fed to the column K2 in liquid form. The tower contains 22 theoretical plates and has a reflux ratio of 0. 06 and pressure 0. Operate at 40 MPa (absolute pressure). From the top, the plate 17 is fed into the feed" top temperature system 51. 7t and the bottom temperature is 170. 7 t. The top product (6) is 3-methyl-1-butene having a purity of more than 95% by mass of 3-methyl-1.butene (see Table 6). The minor components present are the isomers 2-methyl-1-butene and 2-methyl-2-butene, 3-methyl-1-butanol and water. Thus, the top product can be a sold product. However, it is preferred to separate the secondary components and purify 3-methyl-1-butene to greater than 99% by mass in a further processing step. The bottom product (7) from the column K2 mainly contained unreacted 3-methyl-1-butanol (about 49% by mass) and bis(3·methylbutyl)ether (about 47% by mass). In addition, there are especially high boiling compounds, water and methylbutenes. In order to avoid the unintentional accumulation of high-boiling compounds in the loop, the bottom product (7), which is relatively small, is separated and discharged via stream (8). The larger (mass) stream (7b) is mixed with the starting material (1) and returned to the reactor R1. In Example 4, the total yield of methylbutenes calculated from the alcohol content of the stream (1) and the methylbutene content of the stream (6) is 96. The yield of 4% and 3-methyl-1-butene is 94. 2%. These high quality yields are achieved by recycling and dissociation of the unreacted alcohol and the ether formed. Example 5: Method for preparing 3-methyl-1-butene as shown in Figure 4 Example 5 corresponds to the variant shown in Figure 4. Again, similar to the manner in which Example 4 was carried out, a stream containing pure 3-methyl-1-butanol (1 〇 t/h) was assumed to be the feed stream (1). Stream (1) and recycle stream (7a) are fed to column K1. This circulating stream (7a) flows through the bottom of the column K2 through the liquid/liquid separator D1 to remove the aqueous phase (5). The composition of the starting material (1) and the circulating stream (7a) is shown in Table 7. The recycle stream contains not only unreacted 3-methyl-1-butanol, but also a significant component of bis(3-methylbutyl)ether and a high boiling point compound under the selected process conditions. -36- 201105608 Number shown in Figure 4 (1) (7a) (3) Name Feed stream Circulating flow K1 distillate K1 bottom product Mass flow [kg/h] 10000. 00 4335. 84 14302. 47 33. 37 mass ratio [kg/kg] water 〇. 〇〇〇〇〇〇 0. 027034 0. 008195 0. 000096 3-methyl-1-butene 〇. 〇〇〇〇〇〇 0. 001225 0. 000371 0. 000005 2-methyl-1-butene 〇. 〇〇〇〇〇〇 0. 000022 0. 000007 〇. 〇〇〇〇〇〇 2-methyl-2-butene 〇. 〇〇〇〇〇〇 0. 000436 0. 000132 0. 000003 3-methyl·1-butanol 1. 000000 0. 528041 0. 858477 0. 334248 bis(3-methylbutyl)ether 〇. 〇〇〇〇〇〇 0. 440537 0. 132680 0. 372833 High boiling point compound 〇. 〇〇〇〇〇〇 0. 002706 0. 000137 0. 292815 Table 7: Composition of starting material (1), recycle stream (7a) and column K1 distillate (2) and bottom product (3) exemplified in Example 5 Example 1 is used for separation And discharged into the high boiling point compound formed in the separator R1. The tower 1 contains 10 theoretical plates and has a reflux ratio of 0. 07 and pressure 0. Operate at 40 MPa (absolute pressure). The plate 9 from the top of the column is introduced into the stream (1) and the stream (7a). The top temperature system is 179. 2 ° C and the bottom temperature is 1 95. 0 ° C » The top condenser was operated as a partial condenser and the top product (2) was removed as steam. The top product (2) contains about 85 mass% of 3-methyl-1-butanol and about 13 mass% of bis(3-methylbutyl)ether and a high boiling point compound content of about 140 ppm (i.e., large Part of it does not contain high boiling compounds; see Table 7). The bottom product (3) of the column K1 mainly contains 3-methyl-1-butanol (about 33% by mass), bis(3-methylbutyl)ether (about 37% by mass), and a high boiling point compound (about 29). Mass %) The top product (2) of the column 1 is further heated to a reaction temperature of -37 to 201105608 and fed to the reactor R 1 in the form of steam. The reactor is at 2 8 2 t and 0. Operate at 35 MPa (absolute pressure). Under these reaction conditions, the conversion of 3-methyl-1-butanol was about 81%. The composition of the reactor output (4) is shown in Table 8. As shown in Example 4, in addition to 3-methyl-1-butene and the isomers thereof, bis(3-methylbutyl)ether and high-boiling compound ((:15 hydrocarbon) are formed as by-products. Again, the reaction system and 3-A present in the conversion of the (3) bis(3-methylbutyl)ether to 3-methyl-1-butene and 3-methyl-1-butanol The dissociation reaction of keto-1-butanol occurs simultaneously. The content of bis(3-methylbutyl)ether in the output of the reactor (4) is only moderately increased to about 13. 6% by mass. Number shown in Figure 4 (4) (6) (7) (5) Name Reactor output K2 distillate K2 bottom product D1 aqueous phase mass flow [kg/h] 14302. 47 7939. 06 6363. 41 2027. 57 mass ratio [kg/kg] water 0. 149782 0. 006720 0. 328267 0. 972396 3-methyl-1-butene 0. 535293 0. 963666 0. 000850 0. 000048 2-methyl-1-butene 0. 002056 0. 003691 0. 000015 0. 000001 2-methyl-2-butene 0. 012427 0. 022147 0. 000300 0. 000009 3-methyl-1-butanol 0. 164107 0. 000250 0. 368538 0. 027522 bis(3-methylbutyl)ether 0. 135515 0. 003526 0. 300186 0. 000025 high boiling point compound 000820 〇. 〇〇〇〇〇〇 0. 001844 〇. 8 Table 8: The reactor output (4) exemplified in Example 5, the distillate (6) of the column 2 and the bottom product (7) and the aqueous phase of the liquid-liquid separator D1 (5) The composition of the reactor output (4) is at a temperature of 88. Partially condensed at 6 ° C and fed to the column K2 in two phases. The tower contains 18 theoretical plates and has a reflux ratio of 0. 47 and pressure 0. Operate at 30 MPa (absolute pressure). Starting from the top -38- 201105608 Board 1 3 is introduced into the feed. The top temperature is 5 3 .  3 t and the bottom temperature is 1 1 9. 2 t. The top product (6) is 3-methyl-1-butene having a purity of more than 96% by mass of 3-methyl-1-butene (see Table 8). The minor components present are the isomers 2-methyl-2-butene and 2-methyl-1-butene, 3-methyl-1-butanol and water. The bottom product (7) of the column K2 mainly contains unreacted 3-methyl-1-butanol (about 37% by mass), bis(3-methylbutyl)ether (about 30% by mass), and water. (about 3 3 mass%). In addition, high boiling compounds and methylbutenes are present. The stream (7) was cooled to 40 ° C and fed to the liquid-liquid separator D1. Within the separator D1, the water system is separated below its physical solubility limit and discharged in heavy phase (5). Subsequently, most of the non-aqueous stream (i.e., the recycle stream (7a)) is introduced into the distillation column K1. The mass flow and composition of the organic phase (7a) are shown in Table 7 and the mass flow and composition of the aqueous phase (5) are shown in Table 8. In Example 5, the total yield of methylbutenes calculated from the alcohol content of stream (1) and the methylbutene content of stream (6) is 98. The yield of 7% and 3-methyl-1-butene is 96. 2%. These high quality yields are again achieved by the recycle and dissociation of the unreacted alcohol and the ether formed. Compared with Example 4, before the discharge stream (3), the significant materials 3-methyl-1-butanol and bis(3-methylbutyl)ether were significantly depleted by distillation in column K2. Increase the quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described with the aid of the drawings, but the invention is not limited to the embodiments described. The drawing shows: -39- 201105608 Figure 1: Flowchart of a plant implementing a first process variant of the invention: Figure 2: Flowchart of a plant implementing a second process variant of the invention; Figure 3: Implementation Flowchart of a plant of a third process variant of the invention; Figure 4: Flowchart of a plant implementing a fourth process variant of the invention. [Main component symbol description] 1 : Feed stream 2 : Top stream 3 : Bottom stream 4 : Reaction product 4a : Light (organic) phase 5 : Heavy (water) phase 6 : Top product 7 : Bottom product 7 a : Light ( Organic) phase 7b: recycle stream 8 · _ purge stream D1 : liquid-liquid separator R1 : reactor ΚΙ , K2 : tower - 40-

Claims (1)

201105608 VII. Patent application scope: 1. A method for preparing 3-methyl-1-butyrene a) wherein a starting material containing 3-methyl-1-butanol is provided; b) wherein the starting material is subjected to Catalytic dehydration reaction to form a reaction product * c ) wherein the reaction product contains at least the following components: 3-methyl-1-butene, bis(3-methylbutyl)ether, water, and unreacted 3-A Base-1-butanol»d) wherein the reaction product is separated into a low boiling fraction, a high boiling fraction and a water fraction by distillation and by phase separation to remove water; e) wherein the low boiling fraction contains 3-A a 1-butene; f) wherein the high-boiling fraction contains at least bis(3-methylbutyl)ether and unreacted 3-methyl-1-butanol; g) wherein the water fraction contains water in nature And h) wherein the high boiling fraction is at least partially recycled to the dehydration reaction. The method of claim 1, wherein the high boiling fraction is divided into a recycle portion and a purge portion, and only the recycle portion is recycled to the dehydration reaction and the purge portion is discharged from the process, wherein The loop portion is larger than the clear portion. 3. The method of claim 1, wherein the high-boiling fraction is steamed and the high-boiling component formed in the starting material and/or by the dehydration reaction is derived from the distillation The high boiling fraction is separated and discharged. The method of claim 3, wherein the distillation of the high-boiling fraction is carried out after mixing with the starting material. 5. The method of claim 4, wherein the distillation of the high boiling fraction is carried out at a pressure higher than the operating pressure of the dehydration reaction by at least 〇 5 MPa. 6. The method of claim 5, wherein the distillation of the high boiling fraction is carried out in a distillation column, and the overhead product of the distillation column is taken out as a gas and fed to the dehydration reaction. The method of any one of claims 3 to 6, wherein the process steam is produced by the heat of condensation of the overhead product of the distillation of the high boiling fraction. The method of any one of claims 1 to 6, wherein the separation of the reaction product into a low boiling fraction and a high boiling fraction is carried out at a pressure lower than the operating pressure of the dehydration reaction by at least 0.05 MPa. get on. 9. The method of claim 8, wherein the reaction product is fed at least partially in a gas form to separate the reaction product into a distillation of a low boiling fraction and a high boiling fraction. 10. The method of any one of claims 1 to 6, wherein the method follows the method of preparing 3-methyl-1-butanol, a) wherein the preparation of 3-methyl-1-butanol The process comprises distillation as a final process step, the overhead product of the distillation containing 3·methyl-1-butanol, b) wherein the preparation is carried out at a pressure of at least 0.05 MPa higher than the operating pressure of the dehydration reaction. Distillation of the method of 1-butanol, and c) wherein the top of the distillation method for the preparation of 3-methyl-1-butanol is -42-201105608, the system is taken out in a gas form and subsequently taken as a starting material Feed the person to the dehydration reaction. 11. The method of any one of claims 1 to 6, wherein the removing water is carried out in a liquid-liquid separator by simple phase separation. 12. The method of any one of claims 1 to 6, wherein the dehydration reaction is carried out by a single conversion of 50 to 98% by 3-methyl-1-butanol. 13. The method of any one of claims 1 to 6, wherein yttria-modified y-alumina is used as a catalyst in the dehydration reaction. The method of any one of claims 1 to 6, wherein the dehydration reaction is carried out in a gas phase, a temperature range of 250 to 400 ° C, and a pressure range of 0.15 to 0.95 MPa. I5. A method for modifying polypropylene or polyethylene using 3-methyl-1-butene as a comonomer, wherein the 3-methyl-1-butene is in accordance with claims 1 to 14 Prepared by any of the methods. -43-