TW201607922A - Method for co-producing isobutene and ethyl tert-butyl ether from tert-butanol mixture - Google Patents

Abstract

This invention describes a method for co-producing isobutene and ethyl tert-butyl ether from tert-butanol mixture in a catalytic distillation column, wherein catalyzing the tert-butanol mixture with the ethanol undergoes dehydration and etherification. The tert-butanol mixture contains absolute ethanol or aqueous ethanol as the antifreeze agent. The mixture of isobutene and ethyl tert-butyl ether withdrawn from the column top can be further separated, thus high purity isobutene and ethyl tert-butyl ether for fuel-additive are obtained.

Description

Method for co-producing isobutylene and ethyl tert-butyl ether using a third butanol mixture

The invention relates to a method for producing isobutene and ethyl tert-butyl ether (ETBE), in particular to a solution of tert-butanol (TBA) and ethanol. A mixture of aqueous ethanol, which simultaneously produces isobutylene and ethyl tert-butyl ether by catalytic distillation.

Isobutylene is a raw material for the manufacture of chemicals such as alkylated oil, methyl/ethyl tert-butyl ether, diisobutylene, polyisobutylene, methacrylic acid, and butylphenol. The two main sources of isobutene are catalytic cracking and steam cracking. Alternatively, it can be dehydrogenated by butane. However, it is produced as a by-product or a mixture of four carbons. The cost of producing high purity isobutylene is quite high.

The current methods for producing high-purity isobutylene are: 1) extraction from a four-carbon mixture; 2) dehydration using a third butanol; and 3) methyl-tert-butyl ether ether-reaction. Methyl/ethyl tert-butyl ether can increase the octane number and flammability of gasoline. It is widely used in gasoline blending and has more market demand than tert-butyl alcohol, which limits its application in the production of isobutylene. In addition to direct hydrolysis to produce isobutene, tert-butanol can also be directly converted to ethyl tert-butyl ether by reaction with ethanol. Therefore, tert-butanol is one of the important sources of isobutylene and isobutylene derivatives, and also produces isobutylene. An excellent route to ethyl tert-butyl ether.

A sequential reaction process for the manufacture of alkyl tertiary butyl ethers is disclosed in U.S. Patent No. 5,292,964. For example, the third butanol and the ethanol are continuously fed to the first reactor, and the first reactor is discharged in the first distillation column, and the ethanol, ethyl tert-butyl ether mixture is distilled off from the top of the column, and the mixture is in the first The second reactor reacts with the third feedstock/isobutylene to give more ethyl tertiary butyl ether. In addition to the addition of isobutylene to increase the yield of ethyl tert-butyl ether, the top of the first distillation column should be operated at a molar ratio of ethanol to ethyl tert-butyl ether of 1:2 to avoid the reaction. The product/water forms a problem of azeotropy upon distillation, and the flexibility of operation of this process is limited.

U.S. Patent No. 5,527,970 discloses a series of catalysts which increase the conversion of third butanol and the selectivity of ethyl tertiary butyl ether, such as acidic resins, zeolites, but the conversion and selectivity of the freewheeling reactor can be achieved. It is limited by the thermodynamic equilibrium reaction, and the patent does not address the issue of separation of by-product water.

In order to avoid the formation of azeotropes of by-product water and unreacted ethanol, U.S. Patent No. 7,825,282 discloses a two-step process in which a third butanol is dehydrated to give isobutene, and the separated isobutene is reacted with ethanol to obtain an ethyl group. Tributyl ether. This production process has not been effectively simplified and has failed to overcome the problem of tertiary butanol storage.

U.S. Patent No. 4,423,271 specifically teaches the use of an ion exchange resin as a catalyst to dehydrate a third butanol to isobutylene. U.S. Patent Nos. 5,811,620 and 5,849,971 disclose the use of a third butanol to dehydrate an isobutylene in a reactive distillation column having a fluorinated catalyst, but which does not inject ethanol, so it is not possible to co-produce ethyl tert-butyl. The ether can only be subjected to a secondary reaction to etherify isobutylene with ethanol to ethyl tert-butyl ether.

In addition, Yin et al. have investigated the kinetics of the synthesis of ethyl tert-butyl ether and the production of isobutylene by the oxidation of tert-butanol and ethanol by ion exchange resin (International Journal of Chemical Kinetics, 27, 1065-1074, 1995). It indicates that the third butanol and ethanol can simultaneously produce isobutylene and ethyl tert-butyl ether under the catalysis of the acidic catalyst Amberlyst 15.

The above methods are limited in industrial applications. For example, high-purity tert-butyl alcohol is solid at 25 ° C, which is difficult to transport, and is limited in market transactions. At the same time, such restrictions may affect the aforementioned patent offices. The process mentioned must be locally attached to the propylene oxide process or the isobutylene hydration process.

In view of the above, it is a primary object of the present invention to provide a method for co-producing isobutylene with ethyl tert-butyl ether using a third butanol mixture by catalyzing a third butanol mixture with ethanol in a catalytic distillation column. Tributanol can be dehydrated by itself to produce isobutylene, and the third butanol is also reacted with ethanol to form ethyl tert-butyl ether, whereby isobutylene and ethyl tert-butyl ether can be co-produced.

Another object of the present invention is to provide a method for co-producing isobutylene and ethyl tert-butyl ether using a third butanol mixture, which is prepared by mixing anhydrous ethanol or ethanol solution as antifreeze in the third butanol. The tributanol mixture is shipped and traded in the commodity market.

Therefore, in order to achieve the above object, the present invention discloses a method for co-producing isobutylene and ethyl tert-butyl ether using a third butanol mixture, the step of which is to provide a catalytic distillation column which is divided into a catalytic distillation column from top to bottom. a rectification zone, a catalytic zone and a stripping zone; then, injecting a third butanol mixture into a rectification zone of the catalytic distillation column, the third butanol mixture comprising a third butanol and an anhydrous ethanol or ethanol solution; Ethanol is injected into the stripping zone of the catalytic distillation column, so that the combined ethanol/t-butanol molar ratio in the catalytic distillation column is 0.1-2.0; finally, the third butanol mixture and ethanol are catalyzed in the catalytic zone of the catalytic distillation column, The dehydration reaction of the third butanol and the etherification reaction of the third butanol with ethanol occur simultaneously, and the isobutene and the ethyl third butyl ether can be co-produced.

The freezing point of the third butanol at atmospheric pressure is 25.1 °C, which is extremely inconvenient for long-distance storage. Therefore, in order to produce isobutylene and isobutylene derivatives by the propylene oxide/t-butanol co-production process, it is necessary to close the raw material source to make the product It can be quickly delivered to the client; otherwise, considering market demand and production flexibility, it is necessary to transport liquefied isobutylene to increase storage and storage costs.

Alcohol is a commonly used antifreeze agent, which can effectively reduce the freezing point. The present invention is a high-purity third butanol mixed with anhydrous ethanol or ethanol solution as an antifreeze to facilitate the transportation and trading of the third butanol mixture in the commodity market. Because of the formation of azeotrope between water and ethanol, based on cost considerations, the ethanol/water weight ratio close to azeotropic composition at atmospheric pressure of 92/8 is a suitable antifreeze component; when the third butanol mixture is in the catalytic distillation column Under the action of acidic catalyst, such as Amberlyst 35, the third butanol not only dehydrates itself to produce isobutylene, but also the third butanol reacts with ethanol to form ethyl tert-butyl ether, so that the method of the invention can produce isobutene. And ethyl tert-butyl ether.

When the concentration of the ethanol solution (ethanol/water weight ratio of 92/8) is higher than 10.7 wt%, the freezing point of the third butanol mixture is lower than zero degrees Celsius; and the higher the content of the ethanol solution based on the third butanol mixture, The lower the freezing point, the better the ethanol solution content can be adjusted according to the ambient temperature during transportation. The method of the present invention allows the use of such a mixture, which is referred to as the first feed point of the first catalytic distillation column, and if additional anhydrous ethanol or ethanol solution can be added, the second feed value is set; The flexibility afforded by such variable feed concentrations results in a wide range of isobutylene/ethyl tert-butyl ether ratios.

For a better understanding and understanding of the features and advantages of the present invention, the preferred embodiments and the accompanying drawings are described in detail below:

Please refer to FIG. 1 , which is a schematic structural view of a first catalytic distillation column for co-producing isobutylene and ethyl tert-butyl ether according to the present invention.

The first catalytic distillation column contains 37 trays and has an additional reboiler, as well as a condenser. The upper, middle and lower towers are divided into three zones, and the upper zone is a rectification zone X composed of a first tray 1 to a fifteenth tray 15, and the middle section includes an upper reaction bed 91 and a lower reaction bed. The catalytic zone Y of 92 ranges from the sixteenth tray 16 to the thirty-first tray 31, and the lower zone is the stripping zone Z composed of the thirty-second tray 32 to the thirty-seventh tray 37. . The catalytic zone Y can adjust the single type catalyst to the reaction bed 91 at a low temperature and the reaction bed 92 under a high temperature, and is a catalytic zone of a double-bed catalyst. And the catalytic zone Y comprises at least one catalyst which is a solid acidic catalyst, and is particularly suitable for using an ion exchange resin having a sulfonic acid group, which is characterized by an acid capacity (acid capacity). ) 2.0 meq/g or more, such as ion exchange resin Amberlyst® 15, 35, 70, Purolite® CT-275, CT-482, or fluoride treated, sulfated, sulfonated yttrium aluminum oxide, Y-type zeolite Or HZSM-5 zeolite.

As shown in Fig. 1, a high-purity third butanol or third butanol mixture enters the rectification zone X and the stripping zone Z through the lines 11 and 14 respectively, and the third butanol mixture contains the third butanol. And an anhydrous ethanol or ethanol solution as an antifreeze, wherein the absolute ethanol/ethanol solution has a weight concentration of 2% to 30%, preferably a range of 5% to 20%; and the ethanol solution has an ethanol concentration of 80%; Above 100%, the preferred ethanol/water weight ratio is 92/8. The feed position of the third butanol mixture is preferably above the reaction bed 91, and the feed position of the anhydrous ethanol/ethanol solution is preferably below the reaction bed 92 below.

In this way, dehydration of the third butanol and etherification of the third butanol with ethanol occur simultaneously in the upper reaction bed 91 and the lower reaction bed 92 of the first catalytic distillation column. The light weight product, isobutylene and ethyl tertiary butyl ether are extracted from the top of the first catalytic distillation column via line 12. The heavy molecules, water and excess ethanol are extracted from the bottom line 13. The first catalytic distillation column can adjust the ratio of the anhydrous ethanol or ethanol solution to the high-purity third butanol, or inject the insufficient ethanol from the pipeline 14 in a supplementary manner, and control the isobutylene/ethyl tert-butyl ether with high elasticity. The ratio of output is due to the proportion of isobutene/ethyl tert-butyl ether produced, in part due to the amount of ethanol entering the first catalytic distillation column.

Referring to Figure 2, there is shown a process example for the production of isobutylene and ethyl tert-butyl ether using a third butanol mixture according to the present invention.

In the specifically planned product separation and production process, the third butanol mixture fed from line 11 enters the first catalytic distillation column 10, and is fresh from line 14 in order to increase the yield of ethyl tertiary butyl ether. Ethanol also enters the first catalytic distillation column 10. The distillate flowing out from the top of the first catalytic distillation column 10 is rich in isobutylene and ethyl tert-butyl ether. The isobutylene column 40 can be distilled to obtain isobutylene, which is output from the overhead line 41 as a primary product, and the bottom distillation mixture is passed through a pipeline. It is sent to the extractive distillation column 60. The distillate flowing out from the bottom of the first catalytic distillation column 10 is rich in by-product water and unreacted ethanol, and can be distilled into high-purity water through the waste liquid concentration column 50, and sent to the wastewater treatment facility via the line 52, and the overhead steaming The aqueous azeotrope is sent to the extractive distillation column 60 via a line.

The line 61 is sent to the bottom of the extractive distillation column 60, which is an aqueous ethanol, an ethyl third butyl ether, an incompletely reacted third butanol, and an extractant glycol of the extractive distillation column 60 is recirculated from the line 72. The top of the extractive distillation column 60 is obtained by extractive distillation of the water/glycol mixture from the bottom of the column through a line, and the ethyl tert-butyl ether/ethanol/t-butanol mixture is discharged from the top of the column through line 62. The oxygen-containing additive for gasoline can be directly blended into the gasoline pool. The water/glycol mixture is sent to an extractant recovery column 70 where water and ethylene glycol are separated by distillation, water is withdrawn from the top of the column via line 71, sent to a wastewater treatment facility, and ethylene glycol is refluxed from the bottom of the column via line 72 to The distillation column 60 is extracted.

Referring to Figure 3, there is shown a process embodiment for the co-production of isobutylene and ethyl tert-butyl ether using a third butanol mixture contaminated with other butanol isomers.

The impurities produced by the propylene oxide process are present in the crude third butanol product, which is primarily isobutanol or 2-butanol. Since the boiling point of the third butanol is the lowest among the butanol isomers, the third butanol mixture described above is first injected into the butanol column 100 via line 101 and moved through the line 102 at the bottom of the butanol column 100. Except for heavier isomers. Through this design, the impact of the butanol isomer on the process of the present invention can be greatly reduced, and the first catalytic distillation column 10, the isobutylene column 40, the waste liquid concentration column 50, the extractive distillation column 60, and the ethylene glycol recovery tower can be made. 70 is working effectively.

Referring to FIG. 4, the process for further converting the ethyl tertiary butyl ether/ethanol/t-butanol mixture in the overhead line 62 of the extractive distillation column 60 to a high concentration of ethyl tert-butyl ether is carried out according to the present invention. For example, this high concentration ethyl tert-butyl ether is commercially available.

Line 41 isobutylene primary product splits an oil stream with line 62 to second catalytic distillation column 80, and controls the confluence of isobutene/ethanol molar ratio above 1.1 to catalytically distillate ethanol/ethyl tert-butyl ether The ethanol in the mixture is converted to ethyl tertiary butyl ether in a second catalytic distillation column 80, and the ethyl tertiary butyl ether mixture is discharged from the bottom to the deisobutylene column 90, and the excess isobutylene is discharged via line 81. The isobutylene column 90 is distilled to distill off the residual isobutylene, which is passed through line 93 to line 18 to be the isobutylene primary product, and the bottom line 17 to obtain a high concentration of ethyl tertiary butyl ether.

The following example shows the effect of parameter variation when using the commercial software Aspen Plus simulation operation. The parameter conditions of the model are organized as follows:

According to information well known in the art, the flow rate of the third butanol into the first catalytic distillation column 10 shown in Fig. 2 is set to 12.5 ton / hr, and the concentration of the third butanol doped into the ethanol solution is 89.3 wt %. The number of theoretical plates 37 is set from top to bottom in the first catalytic distillation column 10, and a reboiler and a condenser are added, wherein the first to the 31st plates are the catalytic zone Y, the first of 100 ° C The tributanol or tert-butanol mixture is injected from above the 16th tray; the fresh ethanol supplemented at 110 °C is injected from the area below the 32th tray; the contact medium in the first catalytic distillation column is 12% of each tray space; the inner diameter of the column is determined by operating parameters such as column pressure, ethanol / third butanol molar ratio, reflux ratio, distillation / feed ratio, etc., and is used in commercial simulation software programs. The design of the sieve plate is calculated to calculate the tower diameter, and the corresponding catalytic zone tray touch media. The reaction rate of the catalytic distillation process mode is a kinetic parameter of Yin et al. (Kinetics of Liquid-Phase Synthesis of Ethyl tert-Butyl Ether from tert-Butyl Alcohol and Ethanol Catalyzed by Ion Exchange Resin, International Journal of Chemical Kinetics, 27). , 1065-1074, 1995.), the gas-liquid equilibrium calculation is based on the UNIQUAC method of Aspen Plus commercial soft body, combined with the operating parameters of the catalytic distillation tower, can be simulated to calculate the output of isobutylene and ethyl tert-butyl ether . The first catalytic distillation column used in the present invention is set to a column pressure of 2 to 7 kg/cm ² , a column temperature of 20 to 160 ° C, an ethanol/third butanol molar ratio of 0.1 to 2.0, and a reflux ratio of 1 to 2. 20, the top of the distillate / feed weight ratio of 0.3 ~ 0.9, and the preferred setting is the tower pressure of 4 ~ 6 kg / cm ² , the tower temperature of 40 ~ 145 ° C, ethanol / third butanol molar ratio of 0.15 ~ 1.5, reflux ratio of 2~10, tower top distillate / feed weight ratio of 0.5~0.85.

Third butanol conversion rate And isobutylene selectivity ( ) are defined as follows: Wherein F is the molar flow, in and out means entering and leaving the first catalytic distillation column, and TBA, ETBE and IB are designated third butanol, ethyl tertiary butyl ether and isobutylene, respectively.

The extractive distillation column uses ethylene glycol as an extractant, and uses ethylene glycol to change the relative volatility of ethyl tert-butyl ether, ethanol, tert-butanol, etc., and water, so that ethyl tertiary butyl ether and ethanol The third butanol or the like can be distilled off from the top of the extractive distillation column, and the water is discharged from the bottom along with the extracting agent ethylene glycol.

The synthesis reaction rate of ethyl tert-butyl ether in the second catalytic distillation column is based on the kinetic parameters of Sneesby et al. (ETBE Synthesis via Reactive Distillation. 1. Steady-State Simulation and Design Aspects, Ind. Eng. Chem. Res., 36(5), 1855-1869, 1997), the gas-liquid equilibrium calculation is based on the UNIQUAC method of Aspen Plus commercial soft body, combined with the operating parameters of the catalytic distillation column, can be simulated to calculate the conversion of ethanol to ethyl Tributyl ether and produced from the bottom.

Example 1:

The crystallized third butanol (Merck reagent grade, 99.5% or more) was melted in a 45 ° C thermostat, and 126.1 g of third butanol was placed in a 500 mL triangular cone bottle, and an ethanol solution (ethanol/water weight) was added. The ethanol solution/third butanol mixture of 5%, 8%, 10%, and 15% by weight was prepared separately from 92/8). Then plug the rubber stopper with the low temperature alcohol thermometer into the cone bottle, and the temperature measuring point is moved to the middle of the liquid level. The cone bottle is then moved to the freezing cycle tank and gradually cooled from 20 ° C, and shaken, and the cone is inside and outside. After the temperature is equilibrated, each time the temperature is lowered by 0.5 ° C, the temperature change and the precipitation of crystals are observed at any time until the crystallization is precipitated, the temperature is recorded, and the temperature is measured again. The crystallization temperature of the above four different concentrations of the ethanol solution/third butanol mixture was as shown in Table 1, and the results showed that the ethanol solution was used as the antifreeze for the third butanol.

Table 1

Example 2:

This example explores the effect of operating parameters on isobutene selectivity.

This example illustrates that a mixture of 89.3 wt% of a third butanol is used as a feed, supplemented with fresh anhydrous ethanol at 0.562 ton / hr, and the calculated ethanol / third butanol molar ratio of 0.25. The operating parameters of the other first catalytic distillation column are as follows: the column pressure is 4.5 kg/cm ² , the total condensation temperature is 43.2 ° C, and when the reflux ratio is 3.4 and the top distillate/feed weight ratio is 0.76, the size of the first catalytic distillation column can be According to these parameters; therefore, the contact medium of a single tray in the catalytic zone is 0.197 m ³ , and the calculated catalytic zone temperature is 113.1-123.0 ° C, the third butanol conversion rate is 99.2%, and the isobutene selectivity is 89.7%.

Example 3:

This example is to reveal the effect of low ethanol/third butanol molar ratio on isobutene selectivity.

Compared to Example 2, it was not necessary to supplement the fresh anhydrous ethanol/ethanol solution, and the calculated ethanol/t-butanol molar ratio was 0.178. The operating parameters of the other first catalytic distillation column are as follows: the column pressure is 4.5 kg/cm ² , the total condensation temperature is 41.6 ° C, and when the reflux ratio is 3.0 and the top distillate/feed weight ratio is 0.75, the size of the first catalytic distillation column can be These parameters are determined; therefore, the contact medium of a single tray in the catalytic zone is 0.178 m ³ , and the calculated catalytic zone temperature is 110.0-123.2 ° C, the third butanol conversion is 99.2%, and the isobutene selectivity is 93.4%.

Example 4:

This example is to reveal the effect of high ethanol/third butanol molar ratio on isobutylene selectivity.

Compared to Example 2, this example illustrates the use of 85.0 wt% of a third butanol mixture as feed, supplementing fresh anhydrous ethanol by 5.74 ton / hr, and calculating the ethanol / third butanol molar ratio of 1.0. The operating parameters of the other first catalytic distillation column are as follows: the column pressure is 4.5 kg/cm ² , the total condensation temperature is 45.1 ° C, and when the reflux ratio is 4.2 and the top distillate/feed weight ratio is 0.575, the size of the first catalytic distillation column can be These parameters are determined; therefore, the contact medium of a single tray in the catalytic zone is 0.224 m ³ , and the calculated catalytic zone temperature is 115.7-122.4 ° C, the third butanol conversion is 99.2%, and the isobutene selectivity is 85.5%.

Comparing Example 2, Example 3 and Example 4, when the third butanol conversion rate was 99% or more, it was confirmed that the high ethanol/t-butanol molar ratio has a limited effect on reducing the isobutylene selectivity.

Example 5:

This example is to reveal the effect of low catalytic distillation column pressure on isobutylene selectivity.

Compared to Example 2, the column pressure was reduced to 2.5 kg/cm ² . The operating parameters of the other first catalytic distillation column are as follows: the calculated ethanol/third butanol molar ratio is 0.25, the total condensation temperature is 23.9 ° C, and when the reflux ratio is 6.0 and the top distillate/feed weight ratio is 0.765, the first The size of the catalytic distillation column can be determined according to these parameters; therefore, the contact medium of a single tray in the catalytic zone is 0.29 m ³ , and the calculated catalytic zone temperature is 98.2-105.1 ° C, the third butanol conversion is 97.7%, and the isobutene selectivity is calculated. It is 86.0%.

Example 6

This example is to reveal the effect of high catalytic distillation column pressure on isobutylene selectivity.

Compared to Example 2, the column pressure was increased to 6.5 kg/cm ² . The operating parameters of the other first catalytic distillation column are as follows: the calculated ethanol/t-butanol molar ratio is 0.25, the total condensation temperature is 56.7 ° C, and when the reflux ratio is 2.8 and the top distillate/feed weight ratio is 0.75, the first The size of the catalytic distillation column can be determined according to these parameters; therefore, the contact medium of a single tray in the catalytic zone is 0.165 m ³ , and the calculated catalytic zone temperature is 124.4-136.1 ° C, the third butanol conversion is 99.4%, and the isobutene selectivity is calculated. It is 92.0%.

Comparing Example 2, Example 5 and Example 6, when the third butanol conversion rate is above 98%, it can be proved that the high catalytic distillation column pressure has a limited effect on increasing the selectivity of isobutylene, that is, it does not help to lower the ethyl group. Third butyl ether yield.

Table 2 summarizes the operating parameters of Examples 2-6 for the first catalytic distillation column and its effect on the third butanol conversion and isobutylene selectivity; in each of the examples, the theoretical number of plates 37, plus a reboiler And a condenser; catalytic zone range: 16-31 plate; third butanol feed plate number: 15th plate; ethanol feed plate number: 32nd plate; third butanol feed temperature: 100 ° C; ethanol Feed temperature: 110 ° C. Table 3 is the data of the products of Examples 2 to 6.

Table 2

Table 3: Output logistics data for each implementation case

Example 7

This embodiment illustrates the production process of co-producing isobutylene and ethyl tert-butyl ether in a first catalytic distillation column by using a third butanol mixture as a feed, supplementing a fresh 92 wt% ethanol solution. Considering the convenience of storage of tert-butanol (12.5 ton / hr), a third butanol mixture having a 10.7 wt% ethanol solution content was set as the feed, and the freezing point temperature was as in Example 1, which was lower than zero degrees Celsius. The third butanol mixture was injected into the 15th plate at a temperature of 100 ° C, and the fresh ethanol solution was supplemented with 0.611 ton / hr from the line 14 at a temperature of 110 ° C into the 32nd plate, and the calculated ethanol / third butanol molar ratio of 0.25, When the column pressure is 4.5 kg/cm ² , the total condensation temperature is 42.9 ° C, the reflux ratio is 3.4 and the top distillate/feed weight ratio is 0.75, the size of the first catalytic distillation column can be determined according to these parameters, and the contact medium of the single tray in the catalytic zone is determined. The product is 0.195 m ³ , and the calculated catalytic zone temperature is 112.6-123.0 ° C, the third butanol conversion rate is 99.3%, and the isobutylene selectivity is 90.5%.

Other unit operating parameters are as follows. The isobutylene column pressure was 5.0 kg/cm ² , the total condensation temperature was 42.0 ° C, the theoretical number of plates was 13, and a reboiler and a condenser were added. The seventh plate was fed, the reflux ratio was 3.0, and the top distillate/feed weight ratio was 0.775. Waste liquid concentration column pressure 1.1 kg / cm ² , total condensation temperature 80.0 ° C, theoretical plate number 33, plus a reboiler and a condenser, 17th plate feed, reflux ratio 5.0 and top distillate / feed weight ratio 0.189. The extractive distillation column has a glycol/water molar ratio of 5.82, a pressure of 1.05 kg/cm ² , a total condensation temperature of 65.6 ° C, a theoretical plate number of 38, plus a reboiler and a condenser, and the aqueous mixture is fed from the fifth plate. Ethylene glycol was fed from the 34th plate with a reflux ratio of 1.5 and a top distillate/feed weight ratio of 0.394. Ethylene glycol recovery tower pressure 0.272 kg/cm ² , full condensation temperature 66.4 ° C, theoretical plate number 13, plus a reboiler and a condenser, 7th plate feed, reflux ratio 5.0 and top distillate / feed weight More than 0.044.

Table 4: Flow and composition of each logistics number in Example 7

Example 8

This embodiment illustrates the production process of co-producing isobutylene and ethyl tert-butyl ether in a first catalytic distillation column with a third butanol mixture as a feed, without supplementing the fresh ethanol solution. Considering the convenience of storage of tert-butanol (12.5 tons / hour), a third butanol mixture having a 10.7 wt% ethanol solution content was set as the feed, and the freezing point temperature was as in Example 1, which was lower than zero degrees Celsius. The third butanol mixture was injected into the 15th plate at a temperature of 100 ° C, the ethanol / third butanol molar ratio of 0.178, the column pressure of 4.5 kg / cm ² , the total condensation temperature of 41.6 ° C, the reflux ratio of 3.0 and the top distillate / feed When the weight ratio is 0.75, the size of the first catalytic distillation column can be determined according to these parameters. The contact medium of a single tray in the catalytic zone is 0.178 m ³ , and the calculated catalytic zone temperature is 110.0-123.2 ° C, and the third butanol conversion rate is 99.2%. The isobutene selectivity was 93.4%.

Other unit operating parameters are as follows. The isobutylene column pressure was 5.0 kg/cm ² , the total condensation temperature was 42.0 ° C, the theoretical number of plates was 13, and a reboiler and a condenser were added. The seventh plate was fed, the reflux ratio was 3.0, and the top distillate/feed weight ratio was 0.835. Waste liquid concentration column pressure 1.1 kg / cm ² , total condensation temperature 80.0 ° C, theoretical plate number 33, plus a reboiler and a condenser, 17th plate feed, reflux ratio 5.0 and top distillate / feed weight ratio 0.154. The extractive distillation column has a glycol/water molar ratio of 7.5, a pressure of 1.05 kg/cm ² , a total condensation temperature of 65.4 ° C, a theoretical plate number of 38, plus a reboiler and a condenser, and the aqueous mixture is fed from the fifth plate. Ethylene glycol was fed from the 34th plate with a reflux ratio of 1.5 and a top distillate/feed weight ratio of 0.32. Ethylene glycol recovery tower pressure 0.272 kg/cm ² , full condensation temperature 66.4 ° C, theoretical plate number 13, plus a reboiler and a condenser, 7th plate feed, reflux ratio 5.0 and top distillate / feed weight Than 0.034.

Table 5: Flow and composition of each logistics number in Example 8

Example 9

Compared with Example 8, this example illustrates that a mixture of a third butanol containing isobutanol, 2-butanol and water is used as a feed to produce isobutylene and ethyl tert-butyl ether in a catalytic distillation column. The production process does not supplement fresh ethanol. The crude third butanol produced via the propylene oxide process prior to mixing the ethanol solution was about 94.5 wt% pure and contained 1.1% water and 4.4% butanol isomer. In summary, this example controls the impurities in the mixture mainly consisting of isobutanol, 2-butanol and water, and 4.4% of the butanol isomers are distilled off in a butanol column (eg 2.2%). Butanol and 2.2% 2-butanol). The concentration of the ethanol solution in the third butanol mixture was the same as in Example 8, which was about 11.2 wt%.

The operating parameters of the debutanol column are as follows. The column pressure is 0.68 kg/cm ² , the total condensation temperature is 71.2 ° C, the theoretical number of plates is 33, plus a reboiler and a condenser, the 17th plate is fed, the reflux ratio is 1.5 and the top distillate/feed weight Than 0.961. The simulation results show that an anhydrous mixture of isobutanol and 2-butanol can be withdrawn from the bottom of the column, while water, third butanol and ethanol pass through the top of the column. This anhydrous butanol mixture can be further purified or used directly as an oil additive.

The top effluent from the butanol column is injected into the 15th plate of the catalytic distillation column through a line 11 at a temperature of 71.6 ° C. The ethanol/t-butanol molar ratio is 0.178, the column pressure is 4.5 kg/cm ² , and the total condensation is performed. When the temperature is 41.9 ° C, the reflux ratio is 3.0 and the top distillate / feed weight ratio is 0.75, the size of the first catalytic distillation column can be determined according to these parameters. The contact medium of a single tray in the catalytic zone is 0.181 m ³ , and the catalytic region is calculated. The temperature was 111.2-123.3 ° C, the third butanol conversion rate was 99.3%, and the isobutylene selectivity was 92.7%.

Table 6: Example 8, Example 9 First Catalytic Distillation Column Operating Parameters and Results

Example 10:

Compared with the embodiment 8, the embodiment illustrates that the third butanol mixture is used as a feed, and the fresh ethanol solution is not supplemented, and the isobutylene and the ethyl tert-butyl are co-produced through the first catalytic distillation column and the second catalytic distillation column. Ether production process. Considering the convenience of storage of tert-butanol (12.5 tons / hour), a third butanol mixture having a 10.7 wt% ethanol solution content was set as the feed, and the freezing point temperature was as in Example 1, which was lower than zero degrees Celsius. The third butanol mixture was injected into the 15th plate at a temperature of 100 ° C, the ethanol / third butanol molar ratio of 0.178, the column pressure of 4.5 kg / cm ² , the total condensation temperature of 41.5 ° C, the reflux ratio of 3.6 and the top distillate / feed When the weight ratio is 0.75, the size of the first catalytic distillation column can be determined according to these parameters. The contact medium of a single tray in the catalytic zone is 0.191 m ³ , and the calculated catalytic zone temperature is 110.9-123.0 ° C, and the third butanol conversion rate is 99.6%. The isobutylene selectivity was 93.8%.

Other unit operating parameters are as follows. The isobutylene column pressure was 5.0 kg/cm ² , the total condensation temperature was 41.9 ° C, the theoretical number of plates was 13, and a reboiler and a condenser were added. The seventh plate was fed, the reflux ratio was 3.0, and the top distillate/feed weight ratio was 0.842. Waste liquid concentration column pressure 1.1 kg / cm ² , total condensation temperature 80.0 ° C, theoretical plate number 33, plus a reboiler and a condenser, 17th plate feed, reflux ratio 5.0 and top distillate / feed weight ratio 0.145. The extractive distillation column has a glycol/water molar ratio of 8.43, a pressure of 1.05 kg/cm ² , a total condensation temperature of 64.8 ° C, a theoretical plate number of 38, plus a reboiler and a condenser, and the aqueous mixture is fed from the fifth plate. Ethylene glycol was fed from the 34th plate with a reflux ratio of 1.5 and a top distillate/feed weight ratio of 0.312. Ethylene glycol recovery tower pressure 0.272 kg/cm ² , full condensation temperature 66.4 ° C, theoretical plate number 13, plus a reboiler and a condenser, 7th plate feed, reflux ratio 5.0 and top distillate / feed weight More than 0.03.

The second catalytic distillation column pressure is 5.5 kg/cm ² , and the confluent mixture is injected into the fifth plate at a temperature of 60 ° C, the isobutylene/ethanol molar ratio is 1.98, the total condensation temperature is 45.6 ° C, the reflux ratio is 4.0, and the top distillate/feed weight ratio At 0.26, the contact medium of the single tray was 0.041 m ³ in the 6th to 8th plates of the catalytic zone, and the calculated catalytic zone temperature was 52.9-61.1 °C, and the ethanol conversion rate was 93.0%. The isobutene column pressure is 7.0 kg/cm ² , the total condensation temperature is 55.2 ° C, the theoretical number of plates is 18, plus a reboiler and a condenser, the ninth plate is fed, the reflux ratio is 7.0, and the top distillate/feed weight ratio is 0.018. . After the second reaction of the second catalytic distillation column, the yield of the final product isobutylene relative to the third butanol was 82.6%, and the yield of the ethyl third butyl ether relative to the third butanol was 16.9%.

Table 7: Flow and composition of each logistics number in Example 10

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, any changes or modifications of the features and spirits of the present invention should be included in the scope of the present invention.

1‧‧‧First tray
15‧‧‧ fifteenth tray
16‧‧‧16th tray
31‧‧‧Thirty-first tray
32‧‧‧Thirty-second tray
37‧‧‧Thirty-seventh tray
11, 12, 13, 14, 17, 18‧‧‧ pipelines
41, 52, 61, 62, 71, 72 ‧ ‧ pipeline
81, 93, 101, 102‧‧‧ pipelines
10‧‧‧First Catalytic Distillation Tower
40‧‧‧Isobutene Tower
50‧‧‧Waste Concentration Tower
60‧‧‧Extractive distillation tower
70‧‧‧Extractant Recovery Tower
80‧‧‧Second catalytic distillation tower
90‧‧‧Go to the isobutylene tower
91‧‧‧Upper reaction bed
92‧‧‧ under the reaction bed
100‧‧‧to butanol tower
X‧‧·Rectification zone
Y‧‧ ‧ catalytic zone
Z‧‧‧ stripping area

Fig. 1 is a schematic view showing the structure of a first catalytic distillation column for co-producing isobutylene and ethyl tert-butyl ether according to the present invention. Fig. 2 is a schematic view showing the process structure for producing isobutylene and ethyl tert-butyl ether by using a third butanol mixture according to an embodiment of the present invention. Fig. 3 is a schematic view showing the process structure of co-producing isobutylene and ethyl tert-butyl ether using a third butanol mixture according to still another embodiment of the present invention. Fig. 4 is a schematic view showing the process structure for producing isobutylene and ethyl tert-butyl ether by using a third butanol mixture according to another embodiment of the present invention.

1‧‧‧First tray

15‧‧‧ fifteenth tray

16‧‧‧16th tray

31‧‧‧Thirty-first tray

32‧‧‧Thirty-second tray

37‧‧‧Thirty-seventh tray

11, 12, 13, 14‧‧ ‧ pipeline

91‧‧‧Upper reaction bed

92‧‧‧ under the reaction bed

X‧‧·Rectification zone

Y‧‧ ‧ catalytic zone

Z‧‧‧ stripping area

Claims (25)

A method for co-producing isobutylene and ethyl tert-butyl ether using a third butanol mixture, comprising the steps of: providing a catalytic distillation column, which is divided into a rectification zone and a catalytic zone from top to bottom And a stripping zone; injecting a third butanol mixture into the rectification zone of the catalytic distillation column, the third butanol mixture comprising a third butanol and an anhydrous ethanol or ethanol solution; injecting ethanol into the catalytic distillation column The stripping zone is such that the combined ethanol/t-butanol molar ratio in the catalytic distillation column is 0.1 to 2.0; and catalyzing the third butanol mixture and the ethanol in the catalytic zone of the catalytic distillation column, The dehydration reaction of the third butanol and the etherification reaction of the third butanol with ethanol occur simultaneously, and the isobutene and the ethyl third butyl ether are co-produced. The method of claim 1, wherein the absolute concentration of the anhydrous ethanol or ethanol solution in the third butanol mixture is between 2% and 30%. The method of claim 2, wherein the absolute concentration of the anhydrous ethanol or ethanol solution in the third butanol mixture is between 5% and 20%. The method of claim 1, wherein the ethanol solution comprises ethanol in a weight concentration of 80% or more. The method of claim 4, wherein the ethanol solution comprises an ethanol/water weight ratio of 92/8. The method of claim 1, wherein the catalytic zone comprises at least one catalyst, the catalyst being a solid acid catalyst. The method of claim 6, wherein the catalyst of the catalytic zone is configured as a single bed catalytic zone using a single type of catalyst, or has a first temperature above the reaction bed and has a second The double bed catalytic zone of the reaction bed below temperature, the first temperature being lower than the second temperature. The method of claim 1, wherein the catalytic distillation column has a column pressure of 2 to 7 kg/cm 2 (kg/cm ² ). The method of claim 1, wherein the temperature of the catalytic distillation column is 20 to 160 °C. The method of claim 1, wherein in the catalytic distillation column, the reflux ratio is from 1 to 20. The method of claim 1, wherein in the catalytic distillation column, the weight ratio of the overhead distillate to the feed is from 0.3 to 0.9. The method of claim 1, wherein the step of catalyzing the third butanol mixture and the ethanol in the catalytic zone of the catalytic distillation column, and co-producing isobutylene and ethyl tertiary butyl ether, further comprises the step : Distillation, extractive distillation, and secondary catalytic distillation of the product of the catalytic distillation column to purify isobutylene and ethyl tert-butyl ether. . The method of claim 12, wherein the step of distilling the output of the catalytic distillation column comprises the steps of: distilling isobutylene containing ethyl tertiary butyl ether through an isobutylene column to obtain isobutylene; The water is distilled through a waste liquid concentration tower to obtain high-purity water; and the mixture containing ethanol/ethyl tert-butyl ether/water is dehydrated by an extractive distillation tower by extractive distillation to obtain ethanol/B as a gasoline additive. A mixture of a third butyl ether. The method of claim 13, wherein the catalytic distillation column is connected to the isobutylene tube to purify isobutylene, and the catalytic distillation column is further connected to the waste liquid concentration column to purify water. The method of claim 14, wherein the isobutylene column and the waste liquid concentration column are further connected to the extractive distillation column, and the ethanol/ethyl tert-butyl ether/water mixture is injected into the extractive distillation column. At the bottom, and from the top of the extractive distillation column, the ethanol/ethyl tert-butyl ether mixture was evaporated to dryness. The method of claim 15, wherein the top of the extractive distillation column is injected with an extractant from an extractant recovery column, the extractive distillation column is further connected to the extractant recovery tower, and the aqueous extractant at the bottom is sent to The extraction column is used to recover the extractant. The method of claim 16, wherein the extractant recovery column distills high purity water from the top in a distillation manner, and the bottom is a distilled extractant and is refluxed back to the extractive distillation column. The method of claim 16, wherein the extractant is ethylene glycol. The method of claim 13, further comprising: converging all or part of the purified isobutene and the ethanol/ethyl tert-butyl ether mixture, passing through a second catalytic distillation column, and catalytically distilling the ethanol again. Conversion to ethyl tert-butyl ether. The method of claim 19, wherein the confluent mixture has an isobutylene/ethanol molar ratio of greater than 1.1. The method of claim 19, wherein the excess isobutylene at the top of the second catalytic distillation column is fed to the primary finished isobutylene, the bottom is connected to a deisobutylene column, and the deisobutylene column is distilled to obtain an ethyl tertiary butyl group. The ether, the isobutene distilled from the top, also feeds into the primary finished isobutylene. The method of claim 19, wherein the second catalytic distillation column comprises at least one catalyst, the catalyst being a solid acid catalyst. The method of claim 4 or 22, wherein the catalyst is an ion exchange resin having a sulfonate having an acid equivalent of 2.0 meq/g or more. The method of claim 4 or 22, wherein the catalyst is a fluoride treatment, a sulfation treatment, a sulfonation treatment of ruthenium aluminum oxide or a zeolite. The method of claim 1, wherein the step of injecting the third butanol mixture into the rectification zone of the catalytic distillation column further comprises removing the third butanol mixture via a debutanol column. Other butanol isomers of tributanol.