TWI525061B - A method for co-producing isobutene and methyl tert-butyl ether by using tert-butanol mixture - Google Patents

Description

Method for co-producing isobutylene with methyl tert-butyl ether using a third butanol mixture

The invention relates to the simultaneous production of isobutene and methyl tert-butyl ether (MTBE) from a mixture of tert-butanol (TBA) and methanol by catalytic distillation. ) method.

Isobutylene is a raw material for the manufacture of alkylating oil, methyl tert-butyl ether, diisobutylene, polyisobutylene, methacrylic acid, butyl phenol and other chemicals. The two main sources of isobutylene are catalytic cracking and steam cracking. It may also be a dehydrogenation reaction through butane, but it is produced as a by-product or a four-carbon mixture, and the cost of directly separating high-purity isobutylene is relatively high due to the similar boiling point of the composition.

The current methods for producing high-purity isobutylene are: 1) extraction and separation from a four-carbon mixture; 2) dehydration using a third butanol; and 3) methyl-tert-butyl ether-dehydration reaction. Methyl 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. Third butanol can be directly hydrolyzed to produce isobutylene, and can also be directly converted into methyl tert-butyl ether by reaction with methanol. Therefore, tert-butanol is one of the important sources of isobutylene and isobutylene derivatives, and is also producing isobutylene and An excellent route to methyl tert-butyl ether.

U.S. Patent No. 4,918,244 discloses a method of continuously feeding a third butanol and methanol to a catalytic distillation column to produce methyl tert-butyl ether in a single step under catalytic catalysis, but the data show that this method can only Methyl tertiary butyl ether is produced without the formation of isobutylene. US Patent No. 4,925,989 discloses a process for continuously feeding a third butanol, methanol, and isobutylene to a distillation column having a sulfonic acid resin catalytic bed for producing methyl tertiary butyl ether; In order to increase the necessary raw material for the yield of methyl tert-butyl ether, and to consume in the production process, the same as the aforementioned patents, it is not possible to simultaneously produce isobutylene and methyl tert-butyl ether.

Even in the case of a prereactor and a catalytic distillation column (CD column), such as U.S. Patent Nos. 5,705,711 and 5,741,953, no co-production of isobutylene is planned. For example, the latter is to recover the isobutylene mixed with the third butanol and methanol to the main reactor to be converted into methyl tertiary butyl ether, and the catalytic distillation column disposed after the former reactor is used to assist in the improvement of A. The yield of the ternary butyl ether. Furthermore, the methanol/t-butanol molar ratio in the pre-reactor is as high as 2.0, increasing the energy required to recover methanol.

A series of acidic catalysts which increase the conversion of third butanol, such as montmorillonite clay, fluoride-treated Y-type zeolite, yttrium aluminum phosphate, are disclosed in U.S. Patent Nos. 5,081,318, 5,099,072, 5,313, 006, and 5,856,588. (silicoaluminophosphate, SAPO) molecular sieve. These acidic catalysts carry out primary or secondary conversion of tert-butanol and methanol in a high temperature and high pressure reactor to produce isobutylene and methyl tert-butyl ether, but the production processes and methods involved do not employ catalytic distillation. technology.

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. US Patent Nos. US 5,811,620 and US 5,849,971 discloses a method for dehydrating a third butanol in a reaction distillation column having a fluorination-treated catalyst to produce isobutylene, but it is not injected with methanol, so it is impossible to co-produce methyl tert-butyl ether, and only two The secondary reaction etherifies isobutylene with methanol to methyl tertiary butyl ether.

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, and this limitation also affects the aforementioned patents. The process must be in situ attached to the propylene oxide process or the isobutylene hydration process.

In addition, Matouq et al. have investigated the kinetics of the synthesis of methyl tert-butyl ether and the production of isobutylene by third-butanol and methanol from ion exchange resins (International Journal of Chemical Kinetics, 25, 825-831, 1993), which states The third butanol and methanol can simultaneously produce methyl tert-butyl ether and isobutylene under the catalysis of the acidic catalyst Amberlyst 15.

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 methanol as an antifreeze to facilitate the transportation and trading of the third butanol mixture in the commodity market; The butanol mixture is under the action of an acidic catalyst in a catalytic distillation column, such as Amberlyst 35, and the third butanol not only dehydrates itself but produces isobutylene. The olefin, tert-butanol is also reacted with methanol to form methyl tert-butyl ether, so that the process of the invention can be combined to produce isobutylene and methyl tert-butyl ether.

When the methanol concentration is higher than 8.22% by weight, the freezing point of the third butanol mixture will be lower than zero degrees Celsius; and the higher the methanol content based on the third butanol mixture, the lower the freezing point of the mechanism, depending on the transportation Adjust the methanol content by ambient temperature. The process of the present invention allows the use of such a mixture, which is referred to as the first feed point of the catalytic distillation column, and if additional methanol can be added, the second feed value is set; such variable feed The flexibility due to concentration results in a wide range of isobutylene/methyl tert-butyl ether ratios.

1‧‧‧First tray

9‧‧‧ ninth tray

10‧‧‧ Tenth tray

25‧‧‧ twenty-fifth tray

26‧‧‧Twenty-sixth tray

31‧‧‧Thirty-first tray

14, 15, 16, 41, 47, 74, 79‧‧‧ pipelines

82, 83, 86, 88, 101, 102‧‧‧ pipelines

51, 52, 61, 62, 202‧‧‧ pipelines

40‧‧‧ catalytic distillation tower

50‧‧‧First Washing Tower

60‧‧‧Second Water Washing Tower

70‧‧‧Isobutene Tower

80‧‧‧Methanol recovery tower

91‧‧‧Upper reaction bed

92‧‧‧ under the reaction bed

100‧‧‧to butanol tower

200‧‧‧Single Washing Tower

A‧‧‧Water

B‧‧‧methyl tert-butyl ether

C‧‧‧T-butanol

D‧‧‧Methanol

E‧‧‧isobutylene

X‧‧·Rectification zone

Y‧‧ ‧ catalytic zone

Z‧‧‧ stripping area

Fig. 1 is a schematic view showing the structure of a catalytic distillation column for co-producing isobutylene and methyl tertiary butyl ether according to the present invention; and Fig. 2 is an embodiment of the present invention for producing a mixture of a third butanol mixture. Schematic diagram of the process structure of the third butyl ether and isobutylene; Fig. 3 is a schematic view showing the structure of the first water washing tower and the second water washing tower combined with the operation of a single water washing tower according to still another embodiment of the present invention; It is a schematic diagram of a process structure for co-producing methyl tert-butyl ether and isobutylene using a third butanol mixture according to another embodiment of the present invention; and FIG. 5 is a test catalysis according to an embodiment of the present invention. The data change chart of the temperature and concentration in the tower obtained by the distillation tower experiment.

For a better understanding and understanding of the features and advantages of the present invention, the preferred embodiments and the detailed description are as follows: Figure 1 shows the co-production of isobutylene and methyl tertidine. A schematic diagram of the structure of a catalytic distillation column of a base ether comprising 31 trays and having an additional reboiler and a condenser with full or partial condensation function. The upper and lower sections of the tower are divided into three zones, and the upper zone is a rectification zone X composed of the first tray 1 to the ninth tray 9, and the middle section is a catalyst including the upper reaction bed 91 and the lower reaction bed 92. The zone Y ranges from the tenth tray 10 to the twenty-fifth tray 25, and the lower zone is the stripping zone Z composed of the twenty-sixth tray 26 to the thirty-first tray 31. The catalytic zone Y can be adjusted to a catalytic zone of a double-type catalyst according to its needs, wherein in the double-bed catalytic zone, the allowable operating temperature of the catalyst bed on the reaction bed 91 is lower than The allowable operating temperature of the catalyst possessed by the lower reaction bed 92. 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 equivalent ( Acid capacity) above 2.0 meq/g, such as cation exchange resin Amberlyst ^® 15, 35, 70, Purolite ^® CT-275 or Purolite ^® CT-482. The highest allowable operating temperatures of these catalysts are Amberlyst ^® 70 (190 ° C), Purolite ^® CT-482 (190 ° C), Amberlyst ^® 35 (150 ° C), and Purolite ^® CT-482 (130 ° C). ), Amberlyst ^® 15 (120 ° C), other inorganic catalysts, such as fluoride treated, sulfated or sulfonated ruthenium aluminum oxide, Y zeolite or HZSM-5 zeolite, or Mixed use.

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 41 and 47, respectively, and the third butanol mixture is The third butanol and the methanol are included, wherein the weight concentration of the methanol is between 0.1% and 40%, and the preferred range is between 2% and 20%. Preferably, the feed point of the third butanol mixture is above the reaction bed 91, and the feed position of methanol is preferably below the reaction bed 92; and the recovered and recycled methanol can pass through the line 82 to the catalytic distillation column. Any number of boards. It is preferred that the high concentration of methanol is injected from below the catalytic zone Y.

In this way, dehydration of the third butanol and etherification of the third butanol with methanol occur simultaneously in the upper reaction bed 91 and the lower reaction bed 92 of the catalytic distillation column. The light weight product, isobutylene and methyl tert-butyl ether are extracted from the top of the catalytic distillation column via line 14 or line 15. The heavy molecules, water and excess methanol are extracted from the bottom line 16. The catalytic distillation column can adjust the proportion of methanol mixed with high-purity third butanol, or inject methanol by insufficient means, and control the output ratio of isobutylene/methyl tert-butyl ether with high elasticity, and the reason is It is the ratio of the production of isobutylene/methyl tert-butyl ether, which is partly determined by the amount of methanol entering the catalytic distillation column.

Figure 2 is a process example for the co-production of methyl tert-butyl ether and isobutylene using a third butanol mixture. In the specifically planned product separation and production process, the third butanol mixture fed from line 41 and the high concentration of methanol refluxed from line 82 are fed to catalytic distillation column 40. In order to increase the yield of methyl tertiary butyl ether, fresh methanol supplemented from line 47 also enters catalytic distillation column 40. The distillate exiting the top of the catalytic distillation column 40 is enriched in isobutylene and methyl tertiary butyl ether, which is first passed through line 52 to the first water scrubber 50 to extract most of the unreacted methanol. The methanol extraction water is supplied from the bottom pipe of the catalytic distillation column 40 or the bottom pipe of the methanol recovery column 80 through the line 51. To increase the extraction efficiency, the isobutene-rich oily fluid is injected into the first water wash column 50 from the top line of the isobutylene column 70 via line 79 and line 52, if necessary. After extraction through the first water washing column 50, the methanol remaining in the isobutylene raffinate is again extracted in the second water washing column 60 to obtain a mixture of isobutylene and methyl tert-butyl ether, where high purity water is obtained. The second water wash column is injected from the bottom line of the methanol recovery column 80 via line 83 and line 61. The first water wash column 50 and the second water wash column 60 can be combined to reduce equipment costs.

If the first water washing tower 50 and the second water washing tower 60 are combined and designed, referring to FIG. 3, the combined single water washing tower 200 is similar in structure to stack the second water washing tower on the first water washing tower, and the single water washing is performed. The column 200 can receive the distillate flowing out from the top of the catalytic distillation column 40 to extract most of the unreacted methanol, and the water for extracting the methanol is passed from the bottom pipe of the catalytic distillation column 40 or the bottom pipe of the methanol recovery column 80 through the line 51. A line 61 is injected into the single water wash column 200. The raffinate produced by the single water wash column 200 is passed through line 202 to the isobutylene column 70 for distillation.

The raffinate flowing out of the second water washing tower 60 or the single water washing tower 200 after the above-mentioned combined design is mainly composed of isobutylene and methyl tert-butyl ether, and can be passed through the line 62 or the third figure in FIG. The line 202 is injected into the isobutylene column 70 for distillation, and the isobutylene column 70 can distill the isobutylene of the oil phase and the methyl third butyl ether to separate the isobutylene and the methyl third butyl ether. Part of the isobutylene can be recycled to the water wash column to increase methanol extraction efficiency, while another portion is output via line 74 as the primary product. The methanol and water-rich mixture output from the first water washing tower 50 and the second water washing tower 60 is sent to the methanol recovery tower 80 for recovery after the confluence or the methanol extract of the single water washing tower 200. The high concentration methanol mixture recovered is recycled for reuse via line 82 and, if excess, is withdrawn via line 88. The bottom liquid of the methanol recovery column 80 is high-purity water, partially returned to the water washing liquid by the line 83, and refluxed from the bottom of the methanol recovery column 80 to the first water washing tower 50 or the second water washing tower 60, or a single water washing tower. 200, part of which is discharged by line 86 to a wastewater treatment facility.

Figure 4 is a process example for the co-production of methyl tert-butyl ether and isobutylene 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 catalytic distillation column 40, the first water washing column 50, the second water washing column 60, the isobutylene column 70, and the methanol recovery column 80 can be effectively effective. Operation.

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 the information well known in the art, a typical propylene oxide process with an annual capacity of 240,000 tons can produce 640,000 tons of tert-butanol; the third butanol raw material enters the second chart. The flow rate of the catalytic distillation column 40 shown in the catalyst is about 80 tons / hour; the number of theoretical plates in the catalytic distillation column 40 is 33 from top to bottom, and includes a reboiler and a condenser, 11 of which are Between 26 trays is catalytic zone Y, 60 ° C of third butanol or third butanol mixture is injected from above the 10th tray; 70 ° C recovered methanol mixture or supplemented fresh methanol from the 27th The area below the plate is injected; the contact medium in the catalytic distillation column is 15% of each tray space; the inner diameter of the column is determined by operating parameters such as column pressure, methanol/tert-butanol molar ratio, reflux Ratio, distillation amount, feed ratio, etc., and the tower diameter is calculated by the sieve design formula built in the commercial simulation software program, and the corresponding catalytic zone tray touch media volume. The reaction rate of the catalytic distillation process mode is citing the kinetic parameters of Matouq et al. (Kinetics of Liquid Phase Synthesis of Methyl tert-Butyl Ether from tert-Butyl Alcohol and Methanol Catalyzed by Ion Exchange Resin, International Journal of Chemical Kinetics, 25 ( 10), 825-831, 1993.), the calculation of gas-liquid equilibrium and liquid-liquid equilibrium is based on the UNIQUAC and UNIFAC-LL methods of Aspen Plus commercial soft body respectively, with the operating parameters of the catalytic distillation tower, which can be simulated and calculated. Production of isobutylene and methyl tert-butyl ether. The parameter setting of the catalytic distillation column used in the present invention is a column pressure of 1.5 to 7 kg/cm ² , a column temperature of 20 to 160 ° C, a methanol/third butanol molar ratio of 0.1 to 5, a reflux ratio of 1 to 10, and a column. The top distillate/feed weight ratio is 0.3~0.9, and the preferred setting is 3~5kg/cm ² , the tower temperature is 40~145°C, the methanol/t-butanol molar ratio is 0.2~1.5, and the reflux ratio is 1~4, the top distillate/feed weight ratio is 0.6~0.85.

The third butanol conversion ( X _TBA ) and the isobutene selectivity ( S _IB ) are defined as follows: X _TBA = (1 - F _out / F _in | _TBA ) × 100%

S _IB =( F _IB /( F _IB + F _MTBE )| _out )×100% where F is the molar flow, in and out means to enter and exit the catalytic distillation column, TBA, IB and MTBE respectively specify the third butanol, Isobutylene and methyl tertiary butyl ether.

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 conical flask, and 6.3 g of methanol was added for the first time (Merck The reagent grade, 99.9% or more, was obtained by clearing the transparent solution, and the methanol concentration was 4.76%. Then plug the rubber stopper with the low temperature alcohol thermometer into the cone bottle, and the thermometer measuring point is moved to the middle of the liquid level, and the cone bottle is then moved to the freezing cycle tank. The temperature is gradually lowered at 20 ° C, and shaken. After the temperature inside and outside the cone is balanced, 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 occurs, and the temperature is recorded and repeated twice. In the same sample, 5 g of methanol was further added for the second time to obtain a methanol concentration of 8.22%, and the crystallization temperature was measured in the same manner as above. The third time, 3.5 g of methanol was further added to obtain a methanol concentration of 10.5%, and the crystallization temperature was measured in the same manner as described above. The crystallization temperature of the above three different concentrations of the methanol/t-butanol mixture is shown in Table 1. The results show that methanol can be used as the antifreeze for the third butanol. For every 1% increase in the weight concentration of methanol, the crystallization temperature can be lowered by 3.86 °C. .

Example 2:

The mixture was injected into a reboiler of a catalytic distillation column with a mixture of 13% methanol, 45% tert-butanol and 40% water. The inner diameter of the column was 3 inches and the height was 19 inches, which was located in the middle section of the tower. A total of 427 g of dry catalyst Amberlyst 35 was stored in the reaction site. The nitrogen content in the system was 1.38 kg/cm ² before starting.

When the reboiler was heated, the pressure in the catalytic distillation column was controlled at 3.16 kg/cm ² and was subjected to a full reflux operation. After refluxing for 1 hour, a 80%/20% ratio of the third butanol/methanol mixture began to be stably and continuously injected into the catalytic zone. The flow rate of the reflux was controlled at 0.8 kg/hr from the time of injection, and the liquid level control connected to the reboiler was also opened. Six hours after running for six hours. Of the six samples, S-1, S-2, S-3, and S-4 are samples of 1, 5, 9, and 15 inches higher than the reboiler, respectively; the other two samples are S-Top and S. -Btm is taken from the outlet of the condenser and reboiler. Before the sampling, the flow rate of the feed, the overhead distillate and the reflux flow were 1.12 kg/hr, 0.68 kg/hr, and 0.86 kg/hr, respectively, and the temperature data of the test-grade catalytic distillation column is shown in Fig. 5.

The samples were analyzed using a gas chromatograph (Agilent Technologies Model 6890N, TCD model) in conjunction with the ChemStation software. Capillary column (J&W DB-WAX, 30m*0.32mm inner diameter, film thickness 0.5um) is matched with helium gas with a flow rate of 25cm/s. It is maintained at 40°C for 5 minutes and then heated to 100°C at a rate of 10°C per minute. °C is maintained for 1 minute (0.5 uL split is 40:1). The inlet and detector temperatures are 240 and 250 °C, respectively.

The results of the analysis are also shown in Figure 5, where A is water, B is methyl tertiary butyl ether, C is third butanol, D is methanol, and E is isobutylene. It is known that the reboiler (S-Btm) The methanol/t-butanol/water concentration ratio was changed from the initial 13%/45%/40% to 11%/44%/45% at the end and was observed above the catalytic zone position (S-4). The amount of methyl-tert-butyl ether was significantly increased, and the mass fraction ratio of (S-Top) isobutylene to methyl tert-butyl ether was 0.94, which confirmed the third butanol and Methanol can be combined with an acidic resin catalyst Amberlyst 35 to produce isobutylene and methyl tert-butyl ether in a catalytic distillation column.

The solid line in Fig. 5 is simulated based on the operating data: pressure = 3.16 kg/cm ² , reflux ratio = 1.2647, and the distillation amount and feed ratio = 0.6071. The results are in good agreement with the column temperature and composition analysis results. Thus, an example of the use of tert-butanol to produce isobutylene with methyl tert-butyl ether was further explored using this model, as shown in Examples 3 through 12 below.

Example 3

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

The operating parameters of the catalytic distillation column are as follows: column pressure 3.03 kg/cm ² , total condensation temperature 40 ° C, methanol / tert-butanol molar ratio 1.0, when the reflux ratio is 3.0 and the top distillate/feed weight ratio is 0.78, 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 0.676 m ³ , the calculated catalytic zone temperature is 96.3-99.7 ° C, the third butanol conversion is 99.97%, and the isobutene selectivity is calculated. Then it is 51.2%.

Example 4

This example is to reveal the effect of high methanol/t-butanol molar ratio on third butanol conversion.

The operating parameters of the catalytic distillation column are as follows: column pressure 3.03 kg / cm ² , total condensation temperature 40 ° C, methanol / third butanol molar ratio of 1.5, when the reflux ratio of 3.0 and the top distillate / feed weight ratio of 0.83, catalysis The size of the distillation column can be determined according to these parameters; therefore, the calculated contact volume of a single tray of the catalytic zone is 0.728 m ³ , the bottom temperature is 121.6 ° C, the catalytic zone temperature is 97.4-98.6 ° C, and the third butanol conversion rate is 99.95. %, the isobutene selectivity was 46.1%.

It can be demonstrated that the high methanol/t-butanol molar ratio has a limited effect on increasing the yield of methyl tertiary butyl ether.

Example 5

This example is to reveal the effect of reducing column pressure on third butanol conversion.

The operating parameters of the catalytic distillation column are as follows: column pressure 1.53 kg / cm ² , partial condensation temperature 40 ° C, methanol / third butanol molar ratio of 1.0, when reflux ratio of 4.0 and top output / feed weight ratio of 0.4, catalysis The size of the distillation column can be determined according to these parameters; therefore, the contact medium of a single tray in the catalytic zone is 0.609 m ³ , the calculated catalytic zone temperature is 71.0-82.2 ° C, the third butanol conversion is 62.4%, and the isobutene selectivity is 68.0%. .

The gas-liquid two-phase product of the partial condenser is still a mixture of isobutylene and methyl tert-butyl ether. The low column pressure conditions do not help the isotopene to separate isobutylene from methyl tert-butyl ether, while the third The alcohol conversion rate is significantly reduced.

Example 6

This example is to reveal the effect of high column pressure and low methanol/t-butanol molar ratio on third butanol conversion.

The operating parameters of the catalytic distillation column are as follows: the column pressure is 4.53 kg/cm ² , the total condensation temperature is 40 ° C, the methanol/t-butanol molar ratio is reduced to 0.25, when the reflux ratio is 2.5 and the top distillate/feed weight ratio is 0.74. 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 0.523 m ³ , and the calculated catalytic zone temperature is 98.7-113.6 ° C, the third butanol conversion rate is 99.98%, and isobutylene is selected. The rate is 91.2%.

High column pressure not only results in high column temperatures, but also allows for faster reaction rates. Due to the low methanol/t-butanol molar ratio and low reflux ratio, the third half of the catalytic zone simultaneously undergoes the dehydration reaction of the third butanol and the reaction of the methyl tertiary butyl ether to eluate; the ether-extraction reaction increases the selectivity of isobutylene. Moreover, the high isobutylene concentration did not significantly inhibit the third butanol dehydration reaction.

Example 7

Compared to Example 3, the feed above the catalytic zone is a third butanol mixture rather than a pure Tributanol, so the third butanol mixture in this example was freely transportable, the methanol concentration of the upper feed was 17.8%, and the amount of methanol fed below the catalytic zone was halved compared to Example 3.

The catalytic distillation column operating parameters were as in Example 3, the column pressure was 3.03 kg/cm ² , the total condensation temperature was 40 ° C, the methanol/t-butanol molar ratio was 1.0, the reflux ratio was 3.0, and the top distillate/feed weight ratio was 0.78. The operating parameters of the single channel tray of 0.676m ³ are unchanged, and the calculated catalytic zone temperature is 91.2-98.9 ° C, the third butanol conversion rate is 99.78%, and the isobutene selectivity is 51.2%.

As a result, the isobutene selectivity was affected, but the third butanol conversion rate was not.

Example 8

Compared to Example 6, the feed over the catalytic zone was a third butanol mixture rather than pure third butanol. The methanol concentration of the upper feed was 5.1%, while the amount of methanol fed below the catalytic zone was halved compared to Example 6.

The catalytic distillation column operating parameters were as in Example 6, the column pressure was 4.53 kg/cm ² , the total condensation temperature was 40 ° C, the methanol / third butanol molar ratio was 0.25, the reflux ratio was 2.5, and the top distillate/feed weight ratio was 0.74. The operating parameters of the single channel tray of 0.523m ³ are unchanged, and the calculated catalytic zone temperature is 98.0-113.4 ° C, the third butanol conversion rate is 99.95%, and the isobutene selectivity is 92.4%.

As a result, the third butanol conversion and the isobutene selectivity were slightly affected by the feed amount of the third butanol mixture.

Table 2 summarizes the operating parameters of Examples 3-8 for the catalytic distillation column and their effect on the third butanol conversion and isobutylene selectivity. Table 3 is the production of Examples 3~8. Material information.

Table 3 Output logistics data for each implementation case

Example 9

This embodiment illustrates the production process of co-production of isobutylene and methyl tert-butyl ether in a catalytic distillation column by using a third butanol mixture as a feed, without the need to replenish fresh methanol. Considering the convenience of storage of tert-butanol (80 tons/hour), a third butanol mixture having a methanol content of 10.5 wt% was set as a feed, and the freezing point temperature was as in Example 1, which was lower than -12 °C. The third butanol mixture was injected into the ninth plate at a temperature of 60 ° C, about the same amount of methanol (9.58 ton / hr) was refluxed from line 82, and the 26th plate was injected at a temperature of 70 ° C, and the amount of methanol / third butanol was calculated. The ear ratio is 0.5485, the column pressure is 4.23kg/cm ² , the total condensation temperature is 40 ° C, the reflux ratio is 2.24 and the top distillate / feed weight ratio is 0.78. The size of the catalytic distillation column can be determined according to these parameters, and the single tray of the catalytic zone The contact medium product was 0.576 m ³ , and the calculated catalytic zone temperature was 98.4-110.5 ° C, the third butanol conversion rate was 99.9%, and the isobutylene selectivity was 73.6%.

Other unit operating parameters are as follows. The water/methanol molar ratio of the first water washing tower is 3.52, the pressure is 9.03 kg/cm ² , the tower temperature is about 41 ° C, and the theoretical number of plates is 5; the water/methanol molar ratio of the second water washing tower is 10.2, and the pressure is 8.53 kg/cm ^{2 .} The tower temperature is about 39 ° C, and the theoretical number of plates is 5. The isobutylene column pressure was 5.53 kg/cm ² , the total condensation temperature was 40 ° C, the theoretical number of plates was 11, and a reboiler and a condenser were added. The fourth plate was fed, the reflux ratio was 1.696 and the top distillate/feed weight ratio was 0.637. The methanol recovery tower pressure is 2.53kg/cm ² , the total condensation temperature is 40 ° C, the theoretical number of plates is 23, plus a reboiler and a condenser, the 9th plate is fed, the reflux ratio is 2.58 and the top distillate / feed weight ratio is 0.294. .

Example 10

This embodiment illustrates the production process of co-production of isobutylene and methyl tert-butyl ether in a catalytic distillation column with a third butanol mixture as a feed, and in addition to refluxing methanol, fresh methanol is replenished via line 47 to increase methanol/ The third butanol molar ratio gives a higher methyl tertiary butyl ether yield. The storage convenience of the third butanol (80 ton / hr) was considered, and the content of methanol in the third butanol mixture was 10.5% by weight.

The third butanol mixture was injected into the ninth plate via line 41 at a temperature of 60 ° C, methanol (15.7 ton / hr) was recovered and refluxed from line 82, and fresh methanol (9.46 ton / hr) in line 47 was combined, and the temperature was 70. °C was injected into the 26th plate, and the calculated methanol/t-butanol molar ratio was 1.0, the column pressure was 2.73 kg/cm ² , the total condensation temperature was 40 ° C, the reflux ratio was 3.0, and the top distillate/feed weight ratio was 0.82. The size of the distillation column can be determined by these parameters. It is calculated that the contact medium volume of a single tray in the catalytic zone is 0.725 m ³ , the catalytic zone temperature is 92.3-95.9 ° C, the third butanol conversion rate is 99.9%, and the isobutene selectivity is 46.4%.

Other unit operating parameters are as follows. The water/methanol molar ratio of the first water washing tower is 2.15, the pressure is 9.03 kg/cm ² , the tower temperature is about 40 ° C, and the theoretical number of plates is 5; the water/methanol molar ratio of the second water washing tower is 8.48, and the pressure is 8.53 kg/cm ^{2 .} The tower temperature is about 40 ° C, and the theoretical number of plates is 5. The isobutylene column pressure was 5.53 kg/cm ² , the total condensation temperature was 40 ° C, the theoretical number of plates was 11, and a reboiler and a condenser were added. The fourth plate was fed with a reflux ratio of 0.972 and a top distillate/feed weight ratio of 0.618. Methanol recovery tower pressure 2.13kg / cm ² , full condensation temperature 40 ° C, theoretical plate number 28, plus a reboiler and a condenser, 14th plate feed, reflux ratio 1.243 and top distillate / feed weight ratio 0.334 .

Table 5 Flow and composition of each logistics number in Example 10

Example 11

This embodiment illustrates a production process in which a mixture of a third butanol containing isobutanol, 2-butanol, and water is used as a feed to produce isobutylene and methyl tertiary butyl ether in a catalytic distillation column, and does not supplement Fresh methanol. The crude third butanol produced via the propylene oxide process prior to mixing the methanol 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 methanol in the third butanol mixture was the same as in Example 9, which was about 10.71% by weight.

The operating parameters of the debutanol column are as follows. The column pressure is 0.68kg/cm ² , the total condensation temperature is the saturation temperature, the theoretical plate number is 33, plus a reboiler and a condenser, the 17th plate feed, the reflux ratio of 1.5 and the top distillate/feed weight ratio of 0.9607 . 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 methanol 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 ninth plate of the catalytic distillation column through the line 41 at a temperature of 60 ° C. The recovered methanol is refluxed from the line 82 and injected into the 26th plate at a temperature of 70 ° C. The calculated methanol/t-butanol molar ratio was 0.5725. Other parameters for the catalytic distillation column are: column pressure 4.53 kg / cm ² , total condensation temperature is saturation temperature, reflux ratio of 1.6 and top distillate / feed weight ratio of 0.7805, the size of the catalytic distillation column can be determined according to these parameters. It is calculated that the contact medium of a single tray in the catalytic zone is 0.4763 m ³ , the temperature of the catalytic zone is 102.2-113.7 ° C, the conversion of the third butanol is 99.9%, and the selectivity of isobutene is 70.9%.

Other unit operating parameters are as follows. The water/methanol molar ratio of the first water washing tower is 3.72, the pressure is 9.03 kg/cm ² , the tower temperature is about 40 ° C, and the theoretical number of plates is 5; the water/methanol molar ratio of the second water washing tower is 14.3, and the pressure is 8.53 kg/cm ^{2 .} The tower temperature is about 39 ° C, and the theoretical number of plates is 5. Isobutylene tower pressure 6.03kg/cm ² , full condensation temperature is saturation temperature, theoretical plate number 11, plus a reboiler and a condenser, 4th plate feed, reflux ratio 1.993 and top distillate / feed weight ratio 0.606 . The methanol recovery tower pressure is 2.58kg/cm ² , the total condensation temperature is the saturation temperature, the theoretical plate number is 23, plus a reboiler and a condenser, the 11th plate feed, the reflux ratio 3.34 and the top distillate/feed weight ratio 0.262.

Table 6 Flow and composition of each logistics number in Example 11

Example 12

This embodiment discloses the design result of combining the first water washing tower 50 and the second water washing tower 60 into a single water washing tower 200.

Compared to Example 9, the operating parameters of the single water wash column 200 are as follows: a pressure of 8.53 kg/cm ² , a column temperature of about 40 ° C, and a theoretical plate number of 10. The first water washing liquid pipe 61 is injected into the first plate (top), the second water washing liquid pipe 51 is injected into the sixth plate, and the oil phase isobutylene mixed pipe 52 is injected into the tenth plate (bottom bottom).

The three feeds of the single water washing column 200, that is, the flow rate, composition, temperature, pressure, etc. of the first water washing liquid, the second water washing liquid, and the oil phase isobutylene mixture, and the second water washing tower 60 water washing liquid pipe 61 of the embodiment 9. The conditions of the first water washing tower 50 water washing liquid pipe 51 and the oil phase isobutylene mixed pipe 52 and the like are the same. The methanol washing result pipe 202 of the oil phase isobutylene mixture and the methanol washing result pipe 62 of Example 9 were calculated. As shown in Table 7.

Table 7 indicates that the combination of the first water wash column and the second water wash column as a single water wash column does not affect the methanol washing effect.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.

1‧‧‧First tray

9‧‧‧ ninth tray

10‧‧‧ Tenth tray

25‧‧‧ twenty-fifth tray

26‧‧‧Twenty-sixth tray

31‧‧‧Thirty-first tray

14, 15, 16, 41, 47, 82‧‧‧ pipelines

40‧‧‧ catalytic distillation tower

91‧‧‧Upper reaction bed

92‧‧‧ under the reaction bed

X‧‧·Rectification zone

Y‧‧ ‧ catalytic zone

Z‧‧‧ stripping area

Claims (20)

A method for co-producing isobutylene and methyl tert-butyl ether using a third butanol mixture, comprising the steps of: injecting a third butanol mixture into a rectification zone of a catalytic distillation column; and injecting methanol into the catalyst a stripping zone of the distillation column; catalyzing the third butanol mixture and the methanol in a catalytic zone of the catalytic distillation column, the dehydration reaction of the third butanol, and the etherification reaction of the third butanol with the methanol Occurring, co-production of isobutylene and methyl tertiary butyl ether; and washing and distilling the output of the catalytic distillation column to purify isobutylene and methyl tertiary butyl ether, and recovering methanol; wherein, in the catalytic distillation In the column, the top to bottom is divided into the rectification zone, the catalytic zone and the stripping zone. The method of claim 1, wherein the third butanol mixture comprises third butanol and methanol. The method of claim 2, wherein the weight concentration of the methanol is between 0.1% and 40%. The method of claim 2, wherein the weight concentration of the methanol is between 2% and 20%. 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 5, wherein the catalyst in the catalytic zone is an ion exchange resin having a sulfonate, the ion exchange resin being an acid equivalent of 2.0. More than meq/g. The method of claim 5, wherein the catalyst in the catalytic zone is configured as a single-bed catalytic zone or a double-bed catalytic zone using a single type of catalyst, wherein the double-bed catalysis In the zone, the allowable operating temperature of the catalyst contained in one of the upper reaction beds is lower than the allowable operating temperature of the catalyst possessed by the reaction bed. The method of claim 1, wherein the catalytic distillation column has a column pressure of 1.5 to 7 kg/cm ² . The method of claim 1, wherein the catalytic distillation column has a column temperature of 20 to 160 °C. The method of claim 1, wherein the molar ratio of the methanol to the third butanol is 0.1 to 5 in the catalytic distillation column. The method of claim 1, wherein in the catalytic distillation column, the reflux ratio is from 1 to 10. The method of claim 1, wherein in the catalytic distillation column, the weight ratio of the overhead distillate to the feed is 0.3 to 0.9. The method of claim 1, wherein the step of washing and distilling the output of the catalytic distillation column comprises the steps of: passing methanol-containing isobutylene and methyl tertiary butyl ether through a first Washing the tower, allowing methanol to enter the aqueous phase to purify the oil phase of isobutylene and methyl tertiary butyl ether; and distilling the oil phase of isobutylene and methyl tertiary butyl ether to separate isobutylene and methyl tertiary butyl ether And distilling the methanol into the aqueous phase. The method of claim 13, wherein the catalytic distillation column is further connected to the first water washing tower, the first water washing tower extracts unreacted methanol flowing out of the catalytic distillation column, and then recovers the methanol. And injecting the catalytic distillation column. The method of claim 14, wherein the first water washing tower is further The second water washing tower is connected, and the second water washing tower extracts the raffinate flowing out of the first water washing tower to obtain isobutylene, methyl tertiary butyl ether, and methanol for recovery. The method of claim 15, wherein the second water washing tower is further connected to an isobutylene tower, the isobutylene tower distilling the oil phase of the isobutylene and the methyl third butyl ether, and the isobutylene and the methyl group Separation of tributyl ether. The method of claim 15, wherein the first water washing tower and the second water washing tower are further connected to a methanol recovery tower. The method of claim 17, wherein the aqueous phase fluid injected into the first water washing column is from the bottom of the catalytic distillation column or the bottom of the methanol recovery column. The method of claim 17, wherein the aqueous phase fluid injected into the second water washing column is from the bottom of the methanol recovery column. The method of claim 17, wherein the oil phase fluid injected into the first water washing column is from the top of the catalytic distillation column or the top of the isobutylene column.