RU2064919C1 - Method of synthesis of alkyl-tert-alkyl esters - Google Patents

Abstract

FIELD: organic chemistry, chemical technology. SUBSTANCE: olefins were subjected for interaction with alcohols in the presence of solid sulfaonite catalyst at increased temperature and pressure in unit with separated zones of rectification and some reaction zones in which catalyst is placed that is put into liquid, completely or partially. Total vapor current is passed from every low-arranged rectification zone to up-arranged rectification zone by hollow vertical channel and from 5 to 70% of total vapor current - through catalyst layer. EFFECT: improved method of synthesis. 9 ex, 3 dwg, 3 cl

Description

 The alleged invention relates to the field of production of esters by the interaction of olefins and aliphatic alcohols in the presence of an ionic catalyst. These esters are used as high-octane components of motor fuels or are intermediate products in the processes of separation of olefins from hydrocarbon fractions of various origin, obtained on the basis of thermal or thermocatalytic conversion of petroleum feedstocks.

 A known method of producing alkyl tert-alkyl esters [1] where the synthesis of esters is carried out in a reactive distillation reactor. The catalyst is placed in the middle part of the reactor and performs, along with the catalytic properties, the functions of the mass transfer nozzle. Alcohol is fed to the upper part of the catalyst layer, and the hydrocarbon fraction to the lower part of the catalyst layer. The liquid and vapor phases move in opposite streams (countercurrent flow). In this case, the continuous phase is the gas phase, moving from the bottom up through the catalyst bed, irrigated by the liquid phase, flowing down the catalyst from top to bottom.

 The disadvantages of this method are the low permissible velocity of the gas phase through the catalyst bed. With increasing speeds, a “choking” of the catalyst zone occurs. Therefore, for the implementation of the process, large sections (diameters) of the reaction zone are necessary.

The disadvantages of this method are also:
1. The difficulty of ensuring a uniform distribution of fluid and gas flows over the catalyst layer in reactors having a diameter of 5 m or more. The uneven distribution leads to the formation of local non-wetted zones of the catalyst, the temperature in which automatically rises to 90 ^o C or more, which is the limit of thermal stability of the catalyst. In these zones, the catalyst "sinter", loses its catalytic activity. Further, the efficiency of the catalyst, as a mass transfer nozzle, and the productivity of the reactor are reduced due to the possibility of "flooding" of the reaction zone of the reactor with liquid irrigating the catalyst.

 2. The uneven distribution of liquid and gas flows and possible overheating increases the input of by-products, in particular, diisobutylene.

 The above disadvantages are less evident in the method of Pat. USA 4847430, CL prior. 07/11/89/1, cl. C 07 C 41/06, where the ester synthesis process is carried out in a reaction-distillation reactor by the interaction of olefins and aliphatic alcohols in the presence of an ion-exchange catalyst at elevated temperature and pressure with separate distillation and reaction-distillation zones, where the gas stream from the downstream distillation zone to the upstream zone distillations are passed through hollow vertical channels so that the gas stream does not pass through the catalyst bed.

The specified method has the following disadvantages:
1. In the reactor, contact between gas and liquid flows in the catalyst bed is excluded and the catalyst loses the function of the mass transfer nozzle.

 2. In the catalyst layer there is a heating of the reaction mass and its partial evaporation due to the heat of the ether formation reaction. First of all, lower boiling components, in particular, hydrocarbons, evaporate. Due to the evaporation of hydrocarbons, their concentration in the reaction mixture in the lower part of the layer decreases sharply, which reduces the conversion of isobutylene and the yield of ether due to side reactions.

 3. Draining the liquid through the support plate on which the catalyst layer is located is also an ineffective technique and when the loads occurring in the reactive distillation type reactors can change, the liquid will “fail” and does not guarantee “flooding” of the catalyst.

 The aim of the proposed invention is to increase the productivity of the apparatus and increase the yield of ethers.

 To achieve this goal, a method is proposed for producing esters by the interaction of olefins and aliphatic alcohols in the presence of a solid ionic catalyst at elevated temperature and pressure in an apparatus with separate distillation zones and several reaction zones, where the vapor stream from the lower zone is partially passed through the catalyst layer into the upper zone through hollow vertical channels and often in an amount of from 5 to 70%, preferably from 5 to 35% of the total amount of steam flow from the bottom reclining rectification zone. The ratio of flows, it is advisable to adjust by partially overlapping the cross section of the hollow vertical channels.

 The present invention allows you to use the important functions of the catalyst, as mass transfer nozzles in contact with the vapor and liquid flows in the catalyst layer and to continuously supply olefin to the reaction zone with the vapor stream.

 Due to the contact of vapor and liquid flows in the catalyst layer, more favorable conditions for mass transfer are created and the concentration of olefins in the lower part of the catalyst layer increases.

 In the proposed method, the catalyst can also be filled with liquid only in the lower part of the catalyst layer, but it is more preferable to conduct the process in a reactor where the layer is completely filled with liquid.

 An important advantage of the proposed method is a more efficient mixing of the liquid layer with a vapor stream that passes through the catalyst layer, which also increases the efficiency of the process.

 In general, a direct flow of liquid and steam is carried out in each of the reaction zones, but a total countercurrent flow of liquid and steam is reached through the column, which on the one hand does not create strict restrictions on the load in the reaction zones, and on the other hand, it allows reaching a sufficient countercurrent with a sufficient number of reaction zones almost complete conversion of both components.

 When passing through the catalyst bed less than 5% of the vapor stream, the distribution plate below the catalyst bed should have a very small number of openings for the passage of steam. This will lead to the fact that the steam will not pass through the entire thickness of the catalyst layer, but only through separate sections, which will significantly reduce the effectiveness of the catalyst as a mass transfer nozzle.

 When more than 70% of the vapor stream is passed through the catalyst bed, the rate of vapor passage through the catalyst bed increases so significantly that fluid entrainment (ejection) from the catalyst zone begins and, in order to avoid this phenomenon, it is necessary to reduce the load on the distillation apparatus, which, respectively , leads to the fact that its performance becomes at the level of the apparatus of the prototype.

 In Fig.1 shows a diagram of the operation of the plates of the proposed method. In FIG. 1 shows separate two catalyst and one distillation zones, including mass transfer devices (valve, syschastye, cap or other types of bubbler plates).

 The steam stream rising from the underlying rectification zone from the plate 1 is divided into two streams. One stream passes through the hollow channel 3, and the other stream through the distribution plate on which the catalyst is located, and then through the catalyst layer 2 into the overlying distillation zone. Both streams are combined before entering the distillation zone and the vapor passes 3 bubbling plates in countercurrent flowing liquid and enters the overlying reaction zone, where it is similarly divided into two streams and passes a hollow vertical channel 3 and catalyst layer 2.

 The liquid stream through the overflow device 4, located in the upper distillation zone, flows into the lower part of the catalyst layer. Next, the liquid stream together with the steam stream coming from the downstream distillation zone from the plate 1 and the steam stream of the reaction mass, which evaporated due to the generated heat of reaction, flows directly through the catalyst bed. In the upper part, the liquid is separated from the steam and flows through the overflow device 5 to the lower distillation zone onto the plate 1. The liquid passes 3 bubble trays 1 of the middle distillation zone and flows through the overflow device 4 into the lower reaction zone. The liquid contacts the vapor stream in the reaction zone 2 in a similar manner and flows through the overflow device 5 to the downstream distillation zone.

 In FIG. 2, a hollow vertical channel 3 is located outside the apparatus and the steam stream is also divided into two parts. One part passes through channel 3, and the other part passes through catalyst bed 2.

 Figure 3 shows that the liquid from the reaction zone to the downstream distillation zone flows down line 5 located outside the hollow apparatus.

 Example 1 (prototype). The reaction-distillation apparatus consisted of three zones. The upper distillation zone had a diameter of 150 mm and was filled with Raschig rings measuring 15 • 15 mm to a height of 5 m. The middle reaction distillation zone had a diameter of 150 mm and was filled with a molded sulfonate catalyst KIF-1 to a height of 5 m. The catalyst had a diameter of 4 5 mm and a length of 8-10 mm. The lower distillation zone had a diameter of 150 mm and was filled with Raschig rings measuring 15 x 15 mm to a height of 6 m. The volume of the loaded catalyst was 883 l.

The isobutane-isobutylene fraction in an amount of 222.2 kg / h was fed into the lower part of the catalyst layer with a temperature of 70 ^o C. The isobutylene content in the fraction was 45% wt.

Methanol in an amount of 59.4 kg / h was fed into the upper part of the catalyst layer with a temperature of 60 ^o C.

 The reaction-distillation apparatus worked with a reflux ratio of R = 3. The amount of distillate was 127 kg / h; the amount of reflux was 381 kg / h.

The reaction-distillation apparatus worked in the following mode:
top temperature 60 ^o C
temperature in the catalyst layer 65-70 ^o C
cube temperature 140 ^o C
top pressure 8.0 at / cm ²
cube pressure 8.5 kg / cm ²
The isobutane fraction taken from the top of the column had the following composition (% wt.)
Isobutane 34.5-96.5
Methanol 3.0-3.5
Isobutylene 0.5-1.0
Methyl tert-butyl ether, taken from the bottom of the column, in an amount of 154.6 kg / h, had the following composition:
MTBE 99.1
Tert-butanol 0.3
Methanol 0.1
Diisobutylene 0.3
Hydrocarbons C ₅ 0.2.

The conversion of isobutylene was 98.7-99.4%. Selectivity 98-99%.
The productivity of the catalyst, defined as the ratio of the amount of the target product to the amount of loaded catalyst, was 0.175 kg / l of catalyst per hour.

 The entire vapor stream passed through the catalyst bed.

 Example 2 (prototype). Obtaining MTBE from the isobutane-isobutylene fraction was carried out in a reaction-distillation apparatus having 3 zones. The upper distillation zone had a diameter of 150 mm and was filled with a nozzle with Raschig rings measuring 15 x 15 mm to a height of 5 m. The average reaction distillation zone had the following structure. Each of the 3 layers of KIF-1 catalyst had a height of 2.5 m. The catalyst was placed on a support plate. Above the upper and lower catalyst beds are sieve plates of a conventional design. Between the layers of the catalyst are 4 mesh plates. Inside the catalyst layer there are vertical hollow channels for the passage of the vapor stream and for draining the liquid.

 The volume of the loaded catalyst was 132 liters. The liquid stream flowing from the upper distillation zone enters the upper sieve plate and then merges along the vertical channel into the lower part of the catalyst layer. From the lower part of the catalyst layer, the liquid stream, together with the vapor stream generated due to the reaction heat, rises to the upper part of the catalyst layer and flows down the vertical channel onto the underlying sieve plate. The liquid flow in this way passes the reaction-distillation zone and flows from the lower sieve plate through a distribution plate of a conventional design into the lower distillation zone.

 The vapor stream passes the catalyst zone from the bottom up through the openings in the sieve trays and only through the vertical channels in the catalyst layer. The vapor stream does not pass through the catalyst bed.

 The lower distillation zone is filled with a nozzle of Rashig rings measuring 15 • 15 mm to a height of 6 m and in the upper part has a plate for liquid distribution.

The isobutane-isobutylene fraction in an amount of 130.7 kg / h, containing 45% isobutylene, was fed into the lower part of the reaction-distillation zone with a temperature of 70 ^o C.

Methanol in an amount of 34.9 kg / h was fed into the upper part of the catalyst layer with a temperature of 60 ^o C.

 The reflux ratio was 3, the amount of distillate was 74.7 kg / h, the amount of reflux was 224.1 kg / h.

The operation mode of the distillation apparatus:
top temperature 10 ^o C,
the temperature in the catalyst layer 65-75 ^o C,
the temperature of the cube 140 ^o With
top pressure 8.0 kg / cm ² ,
cube pressure 8.5 kg / cm ³ .

 The isobutane fraction contained 3.0-3.5% wt. methanol and up to 1.0% wt. isobutylene.

MTBE, selected from the cube of the column in the amount of 90.9 kg / h, had the following composition (% wt.):
MTBE 99.1
Tert-butanol 0.4
Methanol 0.1
Diisobutylene 0.2
Hydrocarbons C ₅ 0.2
The conversion of isobutylene was 98.7-99.4%. Selectivity 98-99%.
The productivity of the catalyst was 0.69 kg / l of catalyst per hour. Steam flow from the underlying zones did not pass through the catalyst bed.

 Example 3. Obtaining MTBE from the isobutane-isobutylene fraction was carried out in a reactive distillation apparatus having 3 zones. The upper distillation zone had a diameter of 150 mm and was filled with a nozzle with Rashig rings measuring 15 x 15 mm to a height of 5 m. The middle reaction distillation zone had the structure shown in Fig. 1. Each of the 3 layers of KIF-T catalyst had a height of 1.7 m. The volume of the loaded catalyst was 90 liters. Above the upper and below the lower catalyst bed, sieve trays of conventional design are installed. Between the layers of the catalyst installed on 3 sieve plates. The catalyst was placed on a grate, closed with a grid with cells of 2-3 mm, 200 mm above the support plate. The support plate had openings for passing part of the steam stream. Due to the presence of holes, the vapor stream through the catalyst zone passed through both the vertical channel 3 and through the holes in the support plate and through the catalyst layer.

 The liquid stream flowing down from the upper distillation zone enters the upper sieve plate and then flows along the vertical channel 4 into the lower part of the catalyst layer. From the lower part of the catalyst layer, the liquid stream together with the vapor stream generated due to reaction heat, and also passing through the holes in the support plate under the catalyst layer, rises to the upper part of the catalyst layer and flows down the vertical channel 5 onto the underlying screen plate. The liquid flow in this way passes the reaction-distillation zone and flows from the lower sieve plate through a distribution plate of a conventional design into the lower distillation zone.

 The lower distillation zone is filled with a nozzle of Rashig rings measuring 15 • 15 mm to a height of 6 m and in the upper part has a plate for liquid distribution.

The isobutane-isobutylene fraction in an amount of 118.8 kg / h, containing 45% isobutylene, was fed into the lower part of the reaction-distillation zone with a temperature of 70 ^o C.

Methanol in an amount of 31.7 kg / h was fed into the upper part of the catalyst layer with a temperature of 60 ^o C.

 The reflux ratio was 3, the amount of distillate was 67.9 kg / h, the amount of reflux was 203.7 kg / h.

The operation mode of the distillation apparatus:
Top temperature 60 ^o C
The temperature in the catalyst layer 65-75 ^o C
Cube temperature 140 ^o C
Top pressure 8.0 kg / cm ³
Cube pressure 8.5 kg / cm ²
The amount of steam flow passing through the lower catalyst zone was 70% of that coming from the underlying tray, through the middle catalyst zone 40% and through the upper catalyst zone 5%
The isobutane fraction contained 3-3.5% wt. methanol and 0.5-1.0% wt. isobutylene.

MTBE, selected from the cube of the column in the amount of 82.6 kg / h, had the following composition (% wt.):
MTBE 99.1
Tert-butanol 0.3
Methanol 0.1
Diisobutylene 0.3
Hydrocarbons C ₅ 0.2
The conversion of isobutylene was 98.7-99.4%. Selectivity 98-99%.
The productivity of the catalyst was 0.92 kg / l of catalyst per hour.

 Example 4. The reaction-distillation apparatus had a design similar to that described in example 3. The height of the catalyst zones was 2 meters. The volume of the loaded catalyst was 106 liters. Channel 3 was equipped with a gate, allowing you to change its free section.

The isobutane-isobutylene fraction in an amount of 128.1 kg / h, containing 45% isobutylene, was fed into the lower part of the reaction-distillation zone with a temperature of 70 ^o C.

Methanol in the amount of 34.2 kg / h was fed into the upper part of the catalyst layer with a temperature of 60 ^o C.

 The reflux ratio was 3, the amount of distillate was 73.2 kg / h, the amount of reflux was 219.6 kg / h.

The operation mode of the distillation apparatus:
Top temperature 60 ^o C
The temperature in the catalyst layer 65-75 ^o C
Cube temperature 140 ^o C
Top pressure 8.0 kg / cm ²
Cube pressure 8.5 kg / cm ²
The amount of steam flow passing through each catalyst zone was 5% of the incoming from the underlying tray.

 The composition of the distillate and still product is similar to Example 3. The amount of MTBE taken from the bottom of the column was 89.1 kg / h.

The conversion of isobutylene was 98.7-99.4%. Selectivity 98-99%.
The productivity of the catalyst was 0.84 kg / l of catalyst per hour.

 Example 5. The design of the reaction-distillation apparatus was similar to example 4. The height of the catalyst zones was 1.6 m. Channel 3 was equipped with a gate allowing its free cross section to be changed.

 The amount of loaded catalyst was 85 liters.

The isobutane-isobutylene fraction in an amount of 91.5 kg / h, containing 45% isobutylene, was fed into the lower part of the reaction-distillation zone with a temperature of 70 ^o C.

Methanol in an amount of 24.4 kg / h was fed into the upper part of the catalyst layer with a temperature of 60 ^o C.

 The reflux ratio was 3, the amount of distillate was 52.3 kg / h, the amount of reflux was 156.9 kg / h.

The operation mode of the distillation apparatus:
Top temperature 60 ^o C
The temperature in the catalyst layer 65-75 ^o C
Cube temperature 140 ^o C
Top pressure 8.0 kg / cm ²
Cube pressure 8.5 kg / cm ² .

 The amount of steam flow passing through each catalyst zone was 70% of the flow from the underlying tray.

 The composition of the distillate and still product is similar to Example 3. The amount of MTBE taken from the bottom of the column was 63.6 kg / h.

The conversion of isobutylene was 98.7-99.4%. Selectivity 98-99%.
The productivity of the catalyst was 0.75 kg / l of catalyst per hour.

 Example 6. Under the conditions set forth in example 3, ethanol was used instead of methanol. The amount of raw material was 110 kg / h, the amount of ethanol supplied was 41.3 kg / h. The amount of the top product is 62.3 kg / h, the amount of reflux is 186.9 kg / h. The amount of cubic product 89 kg / hour. The top product contained 97.1% isobutane, 0.8% isobutylene and 2.1% ethanol. The bottoms product contained 98.6% ethyl tert-butyl ether, 0.5% trimethylcarbinol, 0.5% ethanol, 0.4% diisobutylene. Conversion of isobutylene to ether 97.3% to diisobutylene 1.5%. Catalyst productivity 0.99 kg / l of catalyst per hour.

 Example 7. Under the conditions described in example 3, butanol was used instead of methanol. The amount of raw material was 100 kg / h, the amount of butanol supplied was 58.3 kg / h. The amount of the top product is 55.6 kg / h, the amount of reflux is 166.8 kg / h. The amount of cubic product 102.7 kg / hour. The top product contained 99% isobutane and 1% isobutylene. The bottoms product contained 97.9 butyl tert-butyl ether, 0.5% trimethyl carbinol, 1% butanol and 0.6% diisobutylene. The conversion of isobutylene was 95.6% in ether and 2.0% in diisobutylene. The productivity of the catalyst is 1.14 kg / l of catalyst per hour.

Example 8. Under the conditions set forth in Example 3, an isopentane-isoamylene fraction was used instead of the isobutane-isobutylene fraction. The amount of fraction is 130 kg / h. The content of isoamylene 35%. The amount of methanol 36.1 kg / hour. The amount of the top product is 101.8 kg / h, the amount of reflux is 254.5 kg / h. The amount of cubic product 64.3 kg / hour. The pressure in the column 4 kg / cm ³ . The top product contained 83% isopentane, 2% isoamylenes and 15% methanol. The bottoms product contained 97.0% methyl tert-amyl ether, 0.5% tert-amyl alcohol, 2% methanol and 0.5% isoamylene dimers. The conversion of isoamylenes to methyl tert-amyl ether was 94.1% to dimers of isoamylenes 1.4%. The productivity of the catalyst was 0.71 kg / l of catalyst per hour.

 As can be seen from the above examples, the use of the proposed method can increase productivity up to 0.92 kg / l of catalyst per hour upon receipt of MTBE against 0.69 kg / l in the known method.

Claims (3)

 1. The method of producing alkyl tert-alkyl esters by reacting olefins with alcohols in the presence of a solid sulfonic ion catalyst at elevated temperature and pressure in an apparatus with separate distillation zones and several reaction zones in which the catalyst is located, fully or partially immersed in a liquid, including transmission steam flow from each downstream distillation zone to the upstream distillation zone through hollow vertical channels, characterized in that from 5 to 70% of the total steam a stream coming from a downstream distillation zone to an upstream distillation zone is passed through a catalyst bed.  2. The method according to claim 1, characterized in that the ratio of flows passed through the hollow vertical channels and through the catalyst bed is controlled by partially overlapping the hollow vertical channels.  3. The method according to claim 1, characterized in that from 5 to 35% of the total vapor stream is passed through the catalyst bed.

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