RU2070217C1 - Method for production of compound gasoline component - Google Patents

Abstract

FIELD: gasoline production. SUBSTANCE: compound gasoline component is a mixture of C₁-C₄-alkyl-tert-C₁-C₅-alkyl ethers and corresponding tert- C₁-C₅-alkanols. The former are prepared by liquid-phase etherification of C₁-C₄-alkanols with C₁-C₅-olefins in presence of acid catalyst such as sulfuric acid or phosphoric acid in a vertical tube reactor filled with catalyst phase containing 5-70 wt % of catalyst, 70-5 wt % of water and C₁-C₄-alkanol to the balance. Tert- C₁-C₅-olefin is loaded into lower section of reactor through nozzles and pipes, and a separated hydrocarbon phase is removed from upper (separation) section of reactor. This phase is washed with water and rectified to produce component containing 10-90 wt % ether and 10-90 wt % tert-alkanol. Content of undesirable admixtures of water, C₁-C₄-alkanols, dimers and polymers of initial olefins in the final product is insignificant. EFFECT: improved process. 9 cl, 1 tbl

Description

The invention relates to methods for producing such gasoline compounding (mixing) components, which are used to increase the octane number of gasoline. More specifically, the invention relates to the production of a high-octane component, which is a mixture of C ₁ -C ₄ alkyl tert-C ₄ -C ₅ alkyl ethers (hereinafter ethers) and the corresponding C ₄ -C ₅ tertiary alcohols (hereinafter tertiary alcohols).

The ethers used as a high-octane gasoline additive are obtained from the corresponding esterification reactions of C ₁ -C ₄ aliphatic alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, sec-butanol and isobutanol with C ₄ -C ₅ tertiary olefins such like isobutylene and isoamylene. The esterification products are, respectively, methyl tert-butyl ether, ethyl tert-butyl ether, propyl and isopropyl tert-butyl ether, butyl, sec-butyl, isobutyl tert-butyl ether, methyl tertamyl ether, ethyl tert-butyl ether, isopropyl tert-butyl ether. Tertiary alcohols are obtained by hydration with water of tertiary C ₄ -C ₅ olefins. Hydration products are, respectively, tert-butyl and tertamyl alcohols [1]
The most rational from the point of view of the synthesis of the specified high-octane component and its subsequent use in gasoline is not the separate production of ethers and the corresponding tertiary alcohols and their subsequent mixing, but the simultaneous production of ethers and tertiary alcohols in the form of a mixture.

When using a mixture of ethers and tertiary alcohols as a component of compounding gasoline with impurities that impair the quality of the target product, the starting alcohols C ₁ -C ₄ , water and dimers, and the polymers of the starting tertiary olefins C ₄ -C _{5 are used} . Starting alcohols C ₁ -C ₄ have a lower octane number compared to the target product, increase the volatility and vapor pressure of gasoline, reduce the stability of gasoline with respect to the octane number, adversely affect the gasket materials of the carburetor and fuel lines. Water is poorly soluble in gasoline, accumulates in fuel tanks and utilities and at low temperatures leads to blockages. Dimers, polymers of isobutylene and isoamylene have a lower octane number compared to the target product, do not allow to reduce the content of harmful impurities in the exhaust gases of cars, and as a result reduce the value of the product as a high-octane component of gasoline compounding.

A known method of producing a compounding component of gasoline, which is a mixture of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBS) [2] In this method, methanol is esterified with isobutylene in the first reaction zone, after which the esterification product is fed with water to the second reaction zone, obtaining thus, a crude mixture of MTBE and TBS, from which water and unconverted C ₄ hydrocarbons are then distilled off. As a catalyst, ion exchange resins are used. The starting reagents are fed into the reactor from top to bottom with the initial molar ratio of methanol to isobutylene (0.3-0.99): 1, i.e. less stoichiometric. The molar ratio of water to isobutylene in the second reaction zone is (1-2.5): 1. Excess water is distilled off from the target product and recycled to the hydration zone, which complicates the process and leads to additional energy costs.

A known method of obtaining a compounding component of gasoline, which is a mixture of MTBE and / or methyltretamyl ether (MTAE) and TBS and / or tretamyl alcohol (TAS), in which simultaneously carry out the etherification with methanol and hydration with water of tertiary olefins With ₄ and / or C ₅ [3 ] As the catalyst using ion exchange resins. However, in this method, unconverted methanol remains in the target product, which reduces its value.

The closest in technical essence to the invention is a method for producing a gasoline compounding component, which is a mixture of alkyl tert-alkyl ethers and the corresponding tertiary alcohols, in which esterification with aliphatic alcohols and hydration with water of tertiary olefins in the presence of an acid catalyst in the liquid phase at a temperature 30-90 ^o With [4] The starting reagents are fed into the reactor from top to bottom. Unconverted hydrocarbons are distilled off from the obtained reaction mixture, and a crude target product is obtained as a bottom product, from which excess water, alcohol and low boiling impurities are distilled off on the next column. As a catalyst, ion exchange resins are used. In the description of the method it is indicated that mineral acids, for example sulfuric acid, can also be used, however, the technology for the separation of sulfuric acid and reaction products has not been described. The need to distill excess water and alcohol from the target product complicates the process.

The aim of the invention is to simplify the process technology and improve the quality of the target product by reducing the content of undesirable impurities of water, C ₁ -C ₄ starting alcohols, dimers and polymers of C ₄ -C ₅ starting tertiary olefins.

This is achieved by the fact that the gasoline compounding component, which is a mixture of C ₁ -C ₄ alkyl-tert-C ₄ -C ₅ alkyl ethers and the corresponding C ₄ -C ₅ tertiary alcohols, is obtained by simultaneously carrying out esterification reactions with C ₁ - aliphatic alcohols C ₄ and water hydration of C ₄ -C ₅ tertiary olefins in the liquid phase in the presence of a homogeneous acid catalyst at a temperature of 50-95 ^o C. The reactions are carried out in a vertical tubular reactor filled with a liquid catalyst phase containing a catalyst, water, C ₁ -C alcohol ₄ in the following ratio of components, wt. catalyst 5-70; water 70-5; alcohol C ₁ -C _{4 the} rest.

The initial C ₄ -C ₅ tertiary olefin is fed to the lower part of the reactor into pipes through nozzles. A hydrocarbon phase containing the desired product and unconverted hydrocarbons is removed from the upper separation part of the reactor, which is separated from the catalyst phase in this separation part. The hydrocarbon phase is washed with water, then the target product is isolated by distillation, and the washing water is supplied together with the starting alcohol C ₁ -C ₄ to the lower part of the reactor.

A distinctive feature of the method is the esterification and hydration reactions in a vertical tubular reactor filled with a liquid catalyst phase containing a homogeneous acid catalyst, water, C ₁ -C ₄ alcohol at the stated ratio of components.

Another difference is that the C ₄ -C ₅ tertiary olefin is fed into the lower part of the reactor into the pipes through nozzles, i.e. from the bottom to the top.

 Another difference is that in the upper separation part of the reactor, the hydrocarbon phase is separated from the catalyst phase, which is then washed with water.

The difference also lies in the fact that the washing water is supplied to the reactor, to its lower part together with the initial alcohol C ₁ -C ₄ , that is, from bottom to top.

 The reactor is a system of vertical pipes enclosed in a common casing. The number and size of pipes are determined by the required plant capacity. In the upper part of the reactor beyond the end of the pipes there is a separation (settling) zone. A coolant is supplied to the annulus of the reactor, which ensures the maintenance of a given temperature. Moreover, since the catalyst is dissolved in the liquid catalyst phase, the evolved reaction heat is removed quickly, efficiently and the reaction mixture does not overheat, which is often the case when using solid catalysts such as ion-exchange resins in other known methods. This allows you to increase the diameter of the pipes, reduce their number in the reactor and thereby simplify its design, manufacture and maintenance. The number of reactors is determined by the required plant capacity. Reactors can be interconnected in series and / or in parallel. The temperature in the reactor may be isothermal and / or adiabatic.

The tertiary olefin C ₄ and / or C ₅ both in pure form and in the form of technical fractions C ₄ and / or C _{5 is} fed to the lower part of the reactor through nozzles that are inside each pipe (at least one nozzle in each pipe). The diameter of the nozzles is chosen so that the linear velocity of the olefins inside the nozzles is 3-10 m / s. As a result of contact with the catalyst phase, the hydrocarbon fraction breaks up into small droplets, which, due to the lower specific gravity, float up through the catalyst, as it were, “standing” phase.

Small drops of need for intensive mass transfer between the sparingly soluble catalyst and hydrocarbon phases, since in this method the esterification and hydration reactions are carried out in a two-phase liquid-liquid system. The reaction products and the catalyst are in two phases, with almost the entire amount of water, catalyst and the main amount of C ₁ -C ₄ alcohol being in the catalyst phase, where the reactions actually occur. The resulting ethers and tertiary alcohols are in the hydrocarbon phase together with unconverted hydrocarbons. The pop-up hydrocarbon phase is easily separated from the catalyst in the upper separation zone and removed from the reactor as a single stream.

A decrease in the linear velocity below 3 m / s leads to an increase in the diameter of hydrocarbon droplets, a decrease in the mass transfer rate below the value required for a given reaction system, as a result of which the productivity of a unit of the reaction volume is reduced. An increase in speed of more than 10 m / s does not affect productivity, however, it increases the energy costs associated with the supply of tertiary C ₄ -C ₅ olefins to the reactor (a higher pressure pump is required).

The reactor is maintained at a temperature not lower than 50 ^{° C.} so that the reactions proceed at a sufficiently high rate and not higher than 95 ^{° C.} in order to prevent the formation of C ₄ -C ₅ tertiary olefins dimers and polymers. The pressure in the reactor is maintained so that the reaction mixture is in the liquid phase, which is achieved in this case at 5-20 atm.

The invention provides the conversion of C ₄ -C ₅ tertiary olefins to the target product with high speed and selectivity, dimer by-products, C ₄ -C ₅ tertiary olefins practically do not form. This is due to the fact that in the catalyst phase the indicated ratio of water and C ₁ -C ₄ alcohol and their specific supply are maintained, so that a ratio of both water and C ₁ -C ₄ alcohol to the tertiary olefin is higher than the stoichiometric ratio in the reactor. Excess water and alcohol inhibits the formation of dimers and polymers. The molar ratio of water to olefin in the reactor creates (3-50): 1, the molar ratio of alcohol: olefin (1.1-15): 1.

A certain amount of C ₁ -C ₄ alcohol and catalyst impurities are almost completely washed with water from the hydrocarbon phase and returned to the reactor. The water taken for washing is spent in the reactor for the formation of tertiary alcohols C ₄ -C ₅ necessary to obtain the target product.

After washing, the hydrocarbon phase is sent to a distillation column, where unconverted C ₄ -C ₅ hydrocarbons are distilled off from the target product, which is taken to a warehouse and then directly used as a gasoline compounding component. Trace amounts of water contained in the washed hydrocarbon phase are almost completely distilled off along with unconverted hydrocarbons.

 Mineral acids, for example, sulfuric, phosphoric, are used as a catalyst; organic sulfonic acids, for example propanesulfonic acid, benzenesulfonic acid; heteropoly acids, for example, molybdenum phosphoric: carboxylic acids, for example, oxalic. It is preferable to use sulfuric acid in an amount of 5-30 wt. or phosphoric acid in an amount of 20-70 wt. in the catalyst phase. You can use various mixtures of these catalysts.

As the olefin feedstock, various isobutylene-containing C ₄ fractions of pyrolysis, cracking, dehydrogenation of oil products and / or isoamylene-containing C ₄ fractions of pyrolysis, cracking, dehydrogenation of oil products are used.

As the C ₁ -C ₄ alcohol, methanol and / or ethanol are preferably used.

 The following mixtures are preferably prepared as a gasoline compounding component: a mixture of MTBE and TBS, a mixture of MTBE, ethyl tert-butyl ether (ETBE) and TBS, a mixture of MTBE, ETBE, MTAE, TBS and TAC.

 Preferably get the target product mixture with a content of ethers of 10-90 wt. and, accordingly, with a content of tertiary alcohols of 10-90 wt.

The proposed method is easier to implement due to the lack of the need to distill excess water and starting alcohol from the target product. Another advantage is that in the target product there are practically no undesirable impurities of water, starting alcohols C ₁ -C ₄ , dimers and polymers of starting tertiary olefins C ₄ -C ₅ , which increases the value of the product as a component of compounding gasoline.

 The possibility of carrying out the invention is confirmed by the following examples. The experimental data for the examples are shown in the table.

 Example 1. The synthesis of a mixture of ethers and tertiary alcohols is carried out in a vertical tubular reactor. The reactor consists of 37 vertical steel pipes, each with a diameter of 200 mm, a height of 15 m, enclosed in a common casing. In the upper part of the reactor beyond the end of the pipes there is a separation zone. Steam condensate is fed into the annulus of the reactor, which maintains a predetermined temperature.

 At the bottom of the reactor, under the pipes, there is a switchgear with nozzles that are inside each pipe (there is one nozzle in the pipe).

 The reactor is filled with a liquid catalyst phase containing phosphoric acid, water, methanol, ethanol in the following ratio, wt. phosphoric acid 46.7; water 44.3; methanol 6.3; ethanol 2.8.

 In the separation zone of the reactor, the level of separation of the two phases is maintained - catalyst and hydrocarbon, which is removed from the top of the reactor.

The initial C ₄ fraction of isobutane dehydrogenation of the following composition, wt.%, Is fed into the reactor through nozzles with a diameter of 2 mm at a speed of 5400 kg / h. propane 0.3; isobutylene 46.1; n-butane 2.0; isobutane 49.1; n-butenes 2.2; divinyl 0.2; pentanes 0.1.

 The linear velocity of hydrocarbons in nozzles is 5.9 m / s.

 Methanol at a speed of 485 kg / h, ethanol 216 kg / h and water after washing the hydrocarbon phase 452 kg / h are also fed into the reactor, in its lower part, (see below).

 The molar ratio of methanol to isobutylene in the reactor is 1.2, ethanol 0.4, water 14.9.

The reactor is maintained at a temperature of 77 ^{° C.} and a pressure of 14 atm.

Coming out of the reactor, the hydrocarbon phase in an amount of 6553 kg / h contains, by weight. isobutylene 2.20; other C ₄ -C ₅ hydrocarbons 44.42; water 0.10; methanol 0.36; ethanol 0.22; methyl tert-butyl ether (MTBE) 20.35; ethyl tert-butyl ether (ETBE) 7.29; tert-butyl alcohol (TBS) 24.92; phosphoric acid 0.13; dimers, polymers of isobutylene 0.01.

 The hydrocarbon phase is fed to the bottom of the wash column, filled with a nozzle Rashig rings. At the top of the wash column, water is supplied in an amount of 403 kg / h.

From the top of the wash column withdraw in the amount of 6504 kg / h hydrocarbon phase, which contains, by weight. isobutylene 2.22; other C ₄ -C ₅ hydrocarbons 44.75; water 0.10; methanol + ethanol 0.01; MTBE 20.50; ETBE 7.34; TBS 25.07; dimers, polymers of isobutylene 0.01.

 From the bottom of the washing column withdraw in the amount of 452 kg / h washing water, which contains, by weight. water 89.16; methanol 5.11; ethanol 3.12; MTBE 0.04; ETBE 0.03; TBS 0.62; phosphoric acid 1.92.

 Wash water is fed to the reactor.

After washing, the hydrocarbon phase is sent to a distillation column where, at a pressure of 5 atm, the spent C ₄ fraction is distilled off in an amount of 3062 kg / h, containing 4.72 wt. isobutylene.

 VAT liquid distillation column is the target product in an amount of 3442 kg / h, containing, by weight. water 0.006; methanol + ethanol 0.02; MTBE 38.72; ETB 13.87; TBS 47.36; dimers, isobutylene polymers 0.02; other impurities 0.004.

The conversion of isobutylene is 94.2%
Example 2. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. phosphoric acid 70.0; water 5.0; methanol 25.0.

The linear velocity of C ₄ hydrocarbons in the nozzles is 4.2 m / s.

 The molar ratio of methanol to isobutylene in the reactor is 8.7, water 3.1.

In the reactor maintain a temperature of 50 ^o C, a pressure of 9 ATM.

 The result is a mixture containing 86.6 wt. MTBE and 13.4 wt. Tbs.

 The conversion of isobutylene is 98.7%. The content of impurities in the ether-alcohol mixture is, wt. methanol 0.05; water 0.006; dimers, polymers of isobutylene 0.01.

 Example 3. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. phosphoric acid 20.0; water 62.3; propanol 17.7. The linear velocity of hydrocarbons in the nozzles is 6.4 m / s.

 The molar ratio of propanol to isobutylene in the reactor is 1.8, water 21.1.

The reactor is maintained at a temperature of 92 ^{° C.} and a pressure of 18 atm.

 The result is a mixture containing 64.4 wt. propyl tert-butyl ether and 35.6 wt. Tbs.

 The conversion of isobutylene is 85.9%. The content of impurities in the ether-alcohol mixture is, wt. propanol 0.04; water 0.007; dimers, isobutylene polymers 0.03.

 Example 4. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. sulfuric acid 23.7; water 70.0; isobutanol 6.3.

As the olefin feed, a mixture is used consisting of a C ₄ fraction as in Example 1 and a C ₅ fraction of isopentane dehydrogenation of the following composition, wt. propane 1.1; butane 3.6; isopentane 59.1; isoamylene 29.2; isoprene 1.4; n-pentane 2.2; n-amylene 2.8; piperylene 0.6
The linear velocity of hydrocarbons in the nozzles is 3.0 m / s.

 The molar ratio of isobutanol to isobutylene in the reactor is 0.7, to isoamylene 0.4, the ratio of water to isobutylene 31.9, to isoamylene 18.3.

The reactor is maintained at a temperature of 64 ^{° C.} and a pressure of 11 atm.

 The result is a mixture containing 10.3 wt. ethers - isobutyl tertbutyl and isobutyl tertamyl ethers and 89.7 wt. tertiary alcohols TBS and tretamyl alcohol (TAS).

The conversion of isobutylene is 80.5% of isoamylene 62.3%
The content of impurities in the ether-alcohol mixture is, wt. isobutanol 0.02; water 0.009; dimers, polymers of isobutylene, isoamylene 0.02.

 Example 5. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. sulfuric acid 5.0; water 64.2; isopropanol 30.8.

As the olefin feedstock, a C ₄ fraction of gasoline pyrolysis of the following composition is used, wt. propane 0.7; isobutylene 28.0; n-butane 9.8; isobutane 2.1; n-butenes 19.7; divinyl 38.9; pentanes 0.8.

 The linear velocity of hydrocarbons in the nozzles is 8.1 m / s.

 The molar ratio of isopropanol to isobutylene in the reactor is 5.0, water 34.7.

In the reactor maintain a temperature of 95 ^o C, a pressure of 20 ATM.

 The result is a mixture containing 77.2 wt. isopropyl tert-butyl ether and 22.8 wt. Tbs.

The conversion of isobutylene is 88.4%
The content of impurities in the ether-alcohol mixture is, wt. isopropanol 0.04; water 0.008; dimers, isobutylene polymers 0.03.

 Example 6. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. sulfuric acid 30.0; water 60.9; secrebutanol 9.1.

As the olefin feed, a C ₅ fraction is used, as in Example 4.

 The linear velocity of hydrocarbons in the nozzles is 7.6 m / s.

 The molar ratio of sec-butanol to isoamylene in the reactor is 1.3, and water is 35.7.

In the reactor maintain a temperature of 53 ^o With a pressure of 5 ATM.

 The result is a mixture containing 37.5 wt. sec-butyl tertamyl ether and 62.5 wt. TAS.

The conversion of isoamylene is 75.1%
The content of impurities in the ether-alcohol mixture is, wt. sec-butanol 0.01; water 0.008; dimers, polymers of isoamylene 0.01.

 Example 7. The synthesis is carried out analogously to example 1, however, the components and their ratio in the catalyst phase are as follows, wt. benzenesulfonic acid 19.4; water 11.3; methanol 16.6; ethanol 52.7.

As the olefin feed, a C ₅ fraction is used, as in Example 4.

 The linear velocity of hydrocarbons in the nozzles is 10.0 m / s.

 The molar ratio of methanol to isoamylene is 4.7, ethanol 10.4, water 4.4.

In the reactor maintain a temperature of 86 ^o With a pressure of 10 ATM.

 The result is a mixture containing 89.8 wt. ethers - methyl tertamyl ether and ethyl tertamyl ether and 10.2 wt. TAS.

The conversion of isoamylene is 79.6%
The content of impurities in the ether-alcohol mixture is, wt. methanol + ethanol 0.04; water 0.007; dimers, isoamylene polymers 0.03.

Claims (8)

1. A method for producing a gasoline compounding component, which is a mixture of a C ₁ -C ₄ -alkyl C ₄ -C ₅ tert-alkyl ether and the corresponding C ₄ -C ₅ tertiary alcohol, by reacting a C ₄ -C ₅ tertiary olefin with a C ₁ -C ₄ aliphatic alcohol and water at a temperature of 50-95 ^o C and a pressure that ensures that the components are in the liquid phase in the presence of a homogeneous acid catalyst and the selection of the target product by distillation from the resulting hydrocarbon phase, characterized in that the process is carried out at a ratio of alcohol and water to a tertiary olefin in excess of stoichiometric in a vertical tubular reactor filled with a liquid catalyst phase containing a catalyst, water, C ₁ -C ₄ aliphatic alcohol in the following ratio, wt. Catalyst 5-70
Water 70-5
C ₁ -C ₄ aliphatic alcohol Else
feeding the C ₄ -C ₅ tertiary olefin to the lower part of the reactor into the pipes through nozzles, separating the hydrocarbon phase containing the target product and unconverted hydrocarbons in the upper separation part of the reactor from the washing phase, washing the hydrocarbon phase with water and supplying the washing water together with the initial C ₁ -C ₄ -aliphatic alcohol in the lower part of the reactor. 2. The method according to claim 1, characterized in that the reactor creates a molar ratio of water: C ₄ -C ₅ tertiary olefin (3-50): 1, a molar ratio of C ₁ -C ₄ aliphatic alcohol C ₄ -C ₅ tertiary olefin (1.1-15): 1. 3. The method according to claim 1, characterized in that the C ₄ -C ₅ tertiary olefin is fed into the reactor pipes through nozzles with a linear velocity of 3-10 m / s. 4. The method according to claim 1, characterized in that methanol and / or ethanol are used as C ₁ -C ₄ aliphatic alcohol. 5. The method according to p. 1, characterized in that as the C ₄ -C ₅ tertiary olefin, isobutylene-containing C ₄ fractions of pyrolysis, cracking, dehydrogenation of oil products and / or isoamylene-containing C ₅ fractions of pyrolysis, cracking, dehydrogenation of oil products are used.  6. The method according to p. 1, characterized in that as a catalyst use sulfuric acid in an amount of 5-30 wt. in the catalyst phase.  7. The method according to p. 1, characterized in that the catalyst used is phosphoric acid in an amount of 20-70 wt. in the catalyst phase. 8. The method according to claim 1, characterized in that the target product contains 10-90 wt. C ₁ -C ₄ alkyl C ₄ -C ₅ tert-alkyl ether and 10-90 wt. corresponding C ₄ -C ₅ tertiary alcohol.

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