RU2127716C1 - Process of alkylation of c4-5 isoparaffins with c3-5 olefins - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: process is carried out in cascade of stirred reactors, or in cascade reactors, or in reactors of other types by feeding catalyst complex containing 85-110 wt % sulfuric acid, and sulfolane. Sulfolane to sulfuric acid weight ratio is maintained at 2-6.99 kg per 100 kg of industrial sulfuric acid, at olefin volumetric feed rate of 0.05-1 h^-1, C_4-5 isoparaffin to C_3-5 olefin weight rate into reactor being from 2.5 to 10 and catalyst complex to hydrocarbon volume ratio being from 1:1 to 0.3:1. Process is carried at 0-10 C. The present invention makes it possible to increase trimethylpentanes in alkylate and simultaneously increase octane number by 4 or 5 points. EFFECT: more efficient alkylation process. 2 cl, 10 ex, 1 tbl

Description

The present invention relates to the petrochemical synthesis, namely, a method for sulfuric acid alkylation of isoparaffins with C ₄ - C ₅ olefins, C ₃ - C ₅ to obtain a high-octane additives for motor fuels.

Existing industrial technologies / Dorogochinsky A.3. et al. Sulfuric acid alkylation of isoparaffins with olefins. -M., Chemistry, 1970; Alkylation Research and industrial design process / ed. L.F. Albright and A.R. Goldsby. -M., Chemistry, 1982 / the production of alkylate using sulfuric acid as a catalyst has the following serious disadvantages:
1 / low selectivity / yield of trimethylpentanes does not exceed 65 wt.% /;
2 / high consumption of acid / up to 90 kg / t of alkylate /;
3 / high acidity of the resulting alkylate and the associated need for a large consumption of alkaline reagents;
4 / the resulting alkylate, as a rule, contains up to 25 wt.% "Light" hydrocarbons C ₅ - C ₇ , which causes environmental problems due to the high volatility of the latter and, accordingly, their release into the environment;
5 / the resulting alkylate contains a large amount / up to 20 wt. % / "heavy" hydrocarbons C ₉ - C ₁₂ , which reduces the octane characteristics of motor fuel;
6 / low solubility of isobutane in sulfuric acid necessitates efficient mixing to create a fine emulsion of hydrocarbons in sulfuric acid. Subsequently, the stable emulsion formed in the reactor must be destroyed. This process proceeds slowly (up to 60-80 min), which leads to the need for a significant increase in the settling zone of the reactor.

In the traditional process, sulfuric acid has a dual role. On the one hand, H ₂ SO ₄ is a catalyst for the process, and on the other hand, H ₂ SO ₄ plays the role of a reaction medium, in the volume of which the main and side reactions occur.

 The same reason - the low solubility of isobutane, as mentioned above, leads to the need to build a large-scale alkylation reactor, at least 50% of which is sulfuric acid. In fact, this characterizes the traditional process as low efficient.

There are a fairly large number of attempts to increase the efficiency of the process by increasing the acid properties of H ₂ SO ₄ by the addition of various salts / US 2319108, 1943; 2344108, 1943; 2,295,608.1942; 2348017, 1944; 2344469, 1944; 2313103, 1944; 3,145,596.1964; 2403931, 1946 /, aliphatic and fatty carboxylic acids and their salts / US 3551514, 1968; 4,426,545, 1983; SU 910563, 1980; US 4,467,132, 1983; 4675305, 1986 / or in the presence of alkylarylsulfonic acids / US 4,544796, 1984; 4,650,918, 1985; 3,655,807, 1970; 4426545, 1983 /, surfactant / DD 285090, 1990; 285091, 1990; SU 988328, 1981), alkyl and arylamines and their combinations with phospho-, sulfone - and sulfamides / US 3956417, 1974; 3,689,590, 1970; 4,017,263, 1974; 3,865,896, 1973; 3,926,839, 1974; 3829525, 1973 /, ammonium salts and other weakly basic substances - up to derivatives of adamantane / US, 4357482, 1981; 4,357,481, 1981; 4,560,825, 1984; JP 63-4491, from 11.01.88, DD 271323, 1988 /, as a rule, not crowned with success in practice.

 Sources / RU 94037755, 09/10/96, RU 95104651, 12/10/96 / found an approach that allows to increase the selectivity of the process by introducing nitroalkanes and sulfolane into the catalyst. In both cases, success was achieved in terms of increasing the yield of trimethylpentanes.

 However, nitromethane is a blasting compound and significant funds must be spent to prevent an explosion. In addition, it is toxic and has a narcotic property. The burning of spent catalyst containing nitromethane will lead to the formation of significant amounts of nitrogen oxides, which poison the environment.

Sulfolane is devoid of all these deficiencies. But the source RU 95104651 only solves the problem of increasing the selectivity of the process, and this goal is achieved in a rather narrow, most often unattainable in practice, range of catalyst composition. In the range of concentrations of sulfuric acid, water and sulfolane claimed by the authors in this source, their ratio must be strictly maintained / for example, at a concentration of sulfolane of 7%, it is possible to use a 95% solution of H ₂ SO ₄ containing 5% H ₂ O, in case 12 % sulfolane only 100% H ₂ SO ₄ should be used.

In laboratory conditions, the strict maintenance of the ratio between sulfolane, H ₂ SO ₄ and water is not difficult, but in practice in a real industrial process this is extremely difficult. The second disadvantage of the solution proposed in RU 95104651 is the high consumption of sulfolane, the amount of which is up to 12 wt.% In sulfuric acid. Given the high cost of sulfolane / ~ $ 4300 / t /, such a large consumption reduces the economic benefits obtained by reducing the acid consumption and increasing the yield of isooctanes to almost zero.

A closer analogue is the method for the alkylation of isoparaffins C ₄ - C ₅ olefins C ₃ - C ₅ , carried out using sulfuric acid / US 3870765 A, 11.02.75 /, which has the disadvantages inherent in the methods of sulfuric acid alkylation.

The above drawbacks deprived described process for alkylating isoparaffins with C ₄ - C ₅ olefins, C ₃ - C ₅ using sulfuric acid, wherein the process is conducted in a cascade of reactors with stirrers or cascade reactor or in the reactors of other types of feed to the reactor catalyst complex, containing sulfuric acid, sulfolane, and the weight ratio of sulfolane / technical sulfuric acid support from 2 to 6.99 kg per 100 kg of industrial sulfuric acid concentration from 85 to 110 wt. % at a volumetric feed rate of olefins in the range from 0.05 to 1 hour ^-1 , a weight ratio of isoparaffins C ₄ - C ₅ to olefins C ₃ - C ₅ - to the reactor from 2.5 to 10 and a volume ratio of catalytic complex / hydrocarbons from 1: 1 to 0.3: 1.

Preferably, the process is carried out by feeding to the reactor a catalytic complex further containing water. Our studies have shown that when the weight ratio of sulfolane / H ₂ SO ₄ is maintained in the process in the range from 2 to 6.99 kg per 100 kg of technical H ₂ SO ₄ , / preferably 3-4 / 100 kg /, in the process apply sulfuric acid in a wide range of concentrations from 85 to 110 wt.%, i.e. under these conditions, there is no longer the strict necessity of strictly maintaining the ratio between sulfolane, H ₂ SO ₄ and water, as required in the source RU 95104651. The catalyst system we found, consisting of sulfolane, sulfuric acid and water of the composition defined above, is a catalytic complex whose properties allow you to achieve unexpected new benefits.

 The ability to carry out the process both at a lowered / 2.5-3 /, and an increased ratio of isbutane / olefins with a high yield of isooctanes.

The ability to work in a wide range of raw material loads - from 0.05 to 1 hour ^-1, in contrast to RU 95104651, where the space velocity was forced to maintain in a very narrow range - 0.29 - 0.32 hour ^-1 .

 The possibility of carrying out the process with a lower ratio of the catalytic complex / hydrocarbons in the reactor is from 1: 1 to 0.3: 1.

 The possibility of reducing the ratio of isobutane / olefins without significantly reducing the yield of isooctanes, as is observed when using sulfuric acid as a catalyst, is a fundamentally new find. The importance of the result is explained by the fact that ~ 80% of the energy consumption of the whole process as a whole is due to the cost of isobutane stripping in the isobutane debutanization column. In the traditional process, in order to reduce energy costs, they are often forced to reduce this ratio to 5-6, even to the detriment of selectivity. In the source RU 95104651, this ratio is supported by 5.7, i.e., it is standard for practice. In our developed catalytic system, the ratio can be reduced by almost 2 times, which makes the process more economical.

 In the practice of operation of the process, they often encounter the problem of working at loads significantly lower than the design load, and the problem of increasing the production of alkylate above the design one.

Operation at low load in the traditional process unambiguously leads to a significant decrease in the selectivity of the process for trimethylpentanes due to the increasing residence time of the products in the sulfuric acid zone. Under these conditions, “hard” acid particles ((H $\genfrac{}{}{0ex}{}{\text{+}}{\text{3}}$ SO ₄ ,, H ₂ SO ₄ ), cracking, transalkylation, etc. are carried out in a solution of sulfuric acid, which leads to the formation of side "light" / C ₅ - C ₇ - hydrocarbons / and "heavy"/> C ₈ - hydrocarbons /, i.e. to reduce the quality of alkylate.

In the presence of sulfolane, the solvation of "hard" acid particles occurs. As our studies have shown, the resulting particles SH ⁺ -S / where S is a solvent, sulfolane / to a much lesser extent than (H $\genfrac{}{}{0ex}{}{\text{+}}{\text{3}}$ SO ₄ , H ₂ SO ₄ ) lead to adverse reactions with an increase in contact time due to low load. In addition, in the presence of sulfolane, the concentration of which in the industrial process can be easily increased or decreased and the properties of catalytic particles are changed accordingly / which is in principle unattainable in technical sulfuric acid in the absence of a solvent / it became possible to control the catalytic properties of the system. The specified regulation of the catalytic activity of the proposed catalytic complex allows us to carry out the process with high selectivity both at high loads of raw materials and at low loads.

In contrast to RU 95104651, where the process is carried out at a standard olefin feed rate of ~ 3 hours ¹ , by adjusting the H ₂ SO ₄ / sulfolane ratio, this invention enables operation in a wide range of feedstock feed rates from 0.05 to 1 hour ^-1 with the achievement of high selectivity for isooctanes.

 The ability to work with a lower ratio of the catalytic complex / hydrocarbons determines a decrease in investment in the construction of new reactor systems. The traditional ratio of catalyst volume to hydrocarbon volume is 1: 1. Due to the possibility of regulating the activity of the catalytic complex we found in the newly designed reactor system, the lower ratio above can be incorporated up to 0.3: 1, which will reduce the volume of reactors and, accordingly, the cost of their construction.

The lower limit of the amount introduced into the H ₂ SO ₄ sulfolane / 2 kg per 100 kg of technical sulfuric acid / as shown by our investigations, the time is determined by the breaking of the emulsion. At the indicated value of the introduced sulfolane, the destruction of the emulsion occurs in 5-8 minutes. A further decrease in the amount of sulfolane added leads to the formation of persistent emulsions and related problems.

 All of the above is illustrated by examples 1-10.

 Example 1

 / RU 95104651 /.

An aqueous solution of sulfuric acid with a concentration of 95.15 wt.% And sulfolane are loaded into a flow reactor with a stirrer so that the concentration of the latter in the solution is 7 wt. % / which corresponds to 7.52 g of sulfolane per 100 g of a solution of H ₂ SO ₄ /.

The isobutane-butylene mixture is continuously fed into the reactor at an isobutane / butylene weight ratio of 5.7. The reactor maintains the volume ratio of a solution of sulfolane in H ₂ SO ₄ to hydrocarbons equal to 1: 1. The volumetric feed rate of olefins to the reactor was 0.28 hour ^-1 .

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 97 theor.%. The trimethylpentane selectivity was 75% by weight. The acid consumption for a ton of alkylate was 52 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 ton. The sulfonal consumption was 3.64 kg / t of alkylate.

 Example 2. Example 2 characterizes the lower level of the amount of sulfonal in the catalytic complex.

 The experiment is carried out under conditions analogous to example 1 with the difference that the weight ratio in the used catalytic complex is 2 kg of sulfonal per 100 kg of industrial sulfuric acid with a concentration of 95 wt.%.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 95 theory%. The trimethylpentane selectivity was 75% by weight. The acid consumption for a ton of alkylate was 52 kg. The steam consumption for debutanization of the obtained alkyl was 750 kg per 1 ton. The sulfonal consumption was 0.97 kg / t of alkylate.

 Example 3. Example 3 characterizes the upper level of the amount of sulfonal in the catalytic complex.

 The experiment is carried out in conditions analogous to example 2 with the difference that 6.99 kg of sulfolane per 100 kg of industrial sulfuric acid with a concentration of 95 wt.% Are used to prepare the catalytic complex.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 98 theory%. The trimethylpentane selectivity was 77% by weight. The acid consumption for a ton of alkylate was 50 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 t.

 The consumption of sulfolane was 3.26 kg / t of alkylate.

 Example 4

 Example 4 characterizes the lower level of the applied ratio of isobutane / olefins.

 The experiment is carried out in conditions analogous to example 2 with the difference that the weight ratio of isobutane / olefins is 2.5.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 98 theory%. The selectivity for trimethylpentanes was 70 wt.%. The acid consumption for a ton of alkylate was 52 kg. The steam consumption for debutanization of the obtained alkylate was 330 kg per 1 t.

 The consumption of sulfolane was 0.97 kg / g of alkylate.

 Example 5

 Example 5 characterizes the upper level of the applied isobutane / olefin ratio.

 The experiment is carried out in conditions analogous to example 2 with the difference that the weight ratio of isobutane / olefins is 10.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 99 theor.%. Trimethylpentane selectivity was 80% by weight. The acid consumption for producing a ton of alkylate was 47 kg. The steam consumption for debutanization of the obtained alkylate was 1315 kg per 1 t.

 The consumption of sulfolane was 0.88 kg / g of alkylate.

 Example 6

 Example 6 characterizes the lower level of acid concentration used to obtain the catalytic complex.

 The experiment is carried out under conditions analogous to example 4 with the difference that technical sulfuric acid with a concentration of 85 wt.% And sulfolane are used to prepare the catalytic complex in the ratio: 100 kg of acid per 6.99 kg of sulfolane.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 95 theory%. The trimethylpentane selectivity was 75% by weight. The acid consumption for a ton of alkylate was 50 kg. The steam consumption for debutanization of the obtained alkylate was 330 kg per 1 t.

 The consumption of sulfolane was 0.93 kg / t of alkylate.

 Example 7

 Example 7 characterizes the upper level of acid concentration used to obtain the catalytic complex.

The experiment is carried out in conditions analogous to example 2 with the difference that 2 kg of sulfolane per 100 kg of oleum having a concentration of 110 wt.% In terms of H ₂ SO ₄ are used to prepare the catalytic complex.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 99 theory.%. The selectivity for trimethylpentanes was 78 wt.%. The acid consumption for a ton of alkylate was 55 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 t.

 The sulfolane consumption was 1.03 kg / t of alkylate.

 Example 8

 Example 8 characterizes the lower level of the volume ratio of the catalytic complex / hydrocarbons used in the reactor.

 The experiment is carried out under conditions analogous to example 2 with the difference that the volume ratio of the catalytic complex / hydrocarbons in the reactor is 0.3.

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 85 theory%. The selectivity for trimethylpentanes was 70 wt.%. The acid consumption for a ton of alkylate was 45 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 t.

 The consumption of sulfolane was 0.84 kg / g of alkylate.

 Example 9

 Example 9 characterizes the upper level of space velocity for olefins.

The experiment is carried out in conditions analogous to example 2 with the difference that the volumetric feed rate of olefins is 1 hour ^-1 .

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 93 theory.%. The trimethylpentane selectivity was 75% by weight. The acid consumption for a ton of alkylate was 58 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 t.

 The consumption of sulfolane was 1.08 kg / t of alkylate.

 Example 10

 Example 10 characterizes the lower level of space velocity for olefins.

The experiment is carried out in conditions analogous to example 2 with the difference that the volumetric feed rate of olefins is 0.05 hour ^-1 .

 As a result of the alkylation reaction, an alkylate was obtained with a yield of 95 theory%. The selectivity for trimethyl pentanes was 77 wt.%. The acid consumption for producing a ton of alkylate was 40 kg. The steam consumption for debutanization of the obtained alkylate was 750 kg per 1 t.

 The consumption of sulfolane was 0.75 kg / t of alkylate.

 For convenience, examples and process indicators are summarized in a table.

Claims (2)

1. The method of alkylation of isoparaffins C ₄ - C ₅ olefins C ₃ - C ₅ using sulfuric acid, characterized in that the process is carried out in a cascade of stirred reactors, or a cascade reactor, or in other types of reactors with a catalytic complex containing sulfuric acid, sulfonal, and the weight ratio of sulfolane / technical sulfuric acid support from 2 to 6.99 kg per 100 kg of industrial sulfuric acid concentration from 85 to 110 wt.%, with a volumetric feed rate of olefins in the range from 0.05 to 1 h ^-1 , weight ratio iso C ₄ - C ₅ olefins of C ₃ - C ₅ to the reactor of 2.5 to 10 and the volume ratio of the catalyst complex / hydrocarbon of from 1: 1 to 0.3: 1.  2. The method according to p. 1, characterized in that the process is carried out with feeding to the reactor a catalytic complex, additionally containing water.

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