RU2434835C1 - Method of producing tert-pentene(s) and alkyl c1-c2-tert-pentyl ether - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of producing tert-pentene(s) and/or alkyl C1-C2-tert-pentyl ether from mixtures of mainly C5-hydrocarbons, containing at least tert-pentenes, isopentane and an admixture of pentadiene(s), and C1-C2 alcohol, involving reaction of tert-pentene(s) with C1-C2 alcohol on a solid acid catalyst and extraction of products via rectification, characterised by that at least catalysed isomerisation of 2-methyl-1-butene into 2-methyl-2-butene [possibly in the presence of hydrogen] is carried out in the initial mixture, the formed mixture undergoes rectification and distillate is output, said distillate mainly containing isopentane, and a stillage residue mainly containing 2-methyl-2-butene, a portion of which preferably undergoes catalysed reaction with C1-C2 alcohol in ether synthesis zone(s), distillate is distilled out of the formed mixture, said distillate containing a mixture of unreacted C5-hydrocarbons with alcohol, which is further used to obtain ether(s), preferably by returning to the ether synthesis zone, and the stillage residue is output, said stillage residue containing alkyl C1-C2-tert-pentyl ether, which is collected as the product and/or undergoes catalysed decomposition and a mixture of pure tert-pentenes is extracted via rectification and removal of alcohol. ^ EFFECT: disclosed method virtually avoids the need to extract alcohol from mixtures with hydrocarbons and extraction thereof from the extract, where the need for basic equipment is at least twice less compared to existing methods. ^ 9 cl, 2 tbl, 6 ex, 3 dwg

Description

The invention relates to the field of production of concentrated tert-alkenes and alkyl C ₁ -C ₂ tert-pentyl ether (ATPE). More specifically, the invention relates to the field of production of 2-methyl-2-butene and ATPE.

Known methods [Oil and gas technology, M., 1994, No. 6, pp. 52-55] for producing ATPE by combining C ₁ -C ₂ alcohol and C ₅ tert-pentenes in the presence of an acidic solid catalyst, in particular acidic cation exchanger, direct-flow (s) or / and reactive distillation apparatus PPA [Pat. Ru-1037632, 1995, bull. No. 7] distillation of the mixture of unreacted hydrocarbons and C ₁ -C ₂ alcohol from the resulting ether, extraction of the alcohol from the mixture with water and its distillation from the aqueous solution.

The main disadvantage of these methods is associated with a high alcohol content in the C ₅ hydrocarbons that are distilled off (usually more than 10% by weight of methanol or more than 4% by weight of ethanol) due to azeotropy, which leads to high energy consumption for its recovery. Another disadvantage is the low conversion of tert-pentenes to ATPE in once-through reactors due to unfavorable chemical equilibrium.

Known methods for producing tert-alkenes by catalyzed decomposition of alkyl tert-alkyl esters in a once-through (s) reactor (s) [US Pat. Ru-2233259, 2004, bull. No. 21] or / and combined PPA [Pat. Ru-2005710, 1994, bull. No. 1] with distillation of the resulting tert-alkenes and at least a portion of the resulting alcohol and subsequent recovery of the alcohol from them by aqueous extraction and isolation of the alcohol from the aqueous solution by distillation. The specified rectification is very energy-intensive, and anhydrous ethanol cannot be isolated by conventional distillation due to its azeotropy with water. The disadvantage of these methods is the complexity and energy consumption of the circuit. The methods do not provide for the production of individual tert-pentenes.

The simultaneous production of ATPE and a mixture of tert-pentenes can be achieved by sequentially combining the above methods for producing ATPE and obtaining tert-pentenes by decomposing part of ATPE. This combination does not exempt from these disadvantages. The scheme is very complex and requires at least 12 main devices (reactors and columns).

We have found a method in which there is practically no need for the extraction of alcohol from mixtures with hydrocarbons and its isolation from the extract. In it, a stream containing primarily 2-methyl-2-butene is initially obtained from the C ₅ fraction, and then part of it is subjected to a catalyzed reaction with alcohol, followed by rectification, in which ether is removed as a bottoms product, and the hydrocarbons and alcohol that are distilled off are returned into the indicated zone of their catalyzed interaction of tert-pentene (s) with alcohol (s). The need for basic equipment in comparison with known methods is reduced by at least half.

We declare:

1. A method for producing tert-pentene (s) and / or C ₁ -C ₂ tert-pentyl ether alkyl from mixtures of predominantly C ₅ hydrocarbons containing at least tert-pentenes, isopentane and an admixture of pentadiene (s), and alcohol C ₁ -C ₂ , including the interaction of tert-pentene (s) with alcohol C ₁ -C ₂ on a solid acid catalyst and the isolation of products by distillation, characterized in that at least the catalyzed isomerization of 2-methyl-1 is carried out in the initial mixture -butene to 2-methyl-2-butene [possibly in the presence of hydrogen], the resulting mixture is subjected to rectification and you odyat distillate containing predominantly isopentane and bottoms residue containing mainly 2-methyl-2-butene, of which preferably subjected to area (s) synthesis of ester (s) catalyzed reacted with an alcohol C ₁ -C _2, of the resultant mixture was distilled distillate containing a mixture of unreacted C ₅ hydrocarbons with alcohol, which is then used to obtain the ester (s), preferably returned to the synthesis zone of the ester (s), and a bottom residue containing C ₁ -C ₂ alkyl tert-pentyl ether, which selected in quality stve product and / or subjected to a catalyzed decomposition and by distillation and purification of the alcohol mixture is isolated pure tert-pentenes.

As methods that contribute to the effective implementation of the method according to claim 1, we declare such methods, characterized in that:

- use a mixture of predominantly C ₅ hydrocarbons obtained by isopentane dehydrogenation, and the distillate distilled off after said isomerization is preferably returned to dehydrogenation directly or after distillation from it of a stream containing predominantly 3-methyl-1-butene;

- in the specified initial hydrocarbon mixture, hydrogenation of pentadiene (s) and isomerization of 2-methyl-1-butene, as well as possibly 3-methyl-1-butene, into 2-methyl-2-butene are carried out sequentially or simultaneously;

- in the specified initial hydrocarbon mixture, pentadiene (s) are hydrogenated and at least 2-methyl-1-butene is hydroisomerized to 2-methyl-2-butene in the presence of a catalyst (s) containing metal (s) selected (e) from the group consisting of Ni, Pd, Pt in chemically unbound form or in the form of compounds, preferably on a solid support;

- initially hydrogenation of pentadienes and / or hydroisomerization of 2-methyl-1-butene to 2-methyl-2-butene in a straight-through liquid hydrocarbon reactor, and then additionally isomerization of 2-methyl-1-butene in 2-methyl-2- butene in a distillation mixture on a solid catalyst inside a column reaction-distillation apparatus in a reaction zone located in the part that strengthens the power supply and / or in the external reaction zone connected to the column distillation apparatus by its inlet from the specified body portion and an outlet flow stream;

- the specified synthesis of alkyl C ₁ -C ₂ tert-pentyl ether is carried out in a direct-flow (s) reaction (s) zone (s), connected (s) with a subsequent distillation column, and / or in a reaction zone with a catalyst located in a strengthening in relation to the power supply of a part of the column reactive distillation system;

- overheating in the indicated (s) direct-flow (s) reaction (s) zone (s) is excluded by its (their) cooling and / or evaporation of part of the reaction mass and / or recirculation of possibly cooled part of the effluent to the entrance to the zone (s);

- in the zone (s) of the synthesis of the specified ether, the content of pentane (s) and / or other C ₅ -hydrocarbons practically not interacting with alcohol is maintained in an amount of from 5 to 90% by weight .;

- excess (e) n-pentane and n-pentenes from the distillation zone upon receipt of the specified ether is removed together with ether and a slight admixture of 2-methyl-2-butene, possibly followed by distillation from ether, or as a side selection from the bottom of the distillation zones.

Distillation or reaction-distillation processes can be implemented either in one column apparatus, or using several (usually two) columns connected by countercurrent flows of liquid and steam and technically functioning as one reaction or reaction-distillation column. The term “reinforcing part” (as the “comprehensive part”) is used in the conventional sense. In particular, the reinforcing part is a combination of mass transfer devices (plates, etc.), including, if available, a reaction zone between the point (plate) of the feed of the processed mixture (“feed”) and the reflux condenser.

In the synthesis of ATPE in a direct-flow (s) reactor (s), various acidic solid catalysts can be used, preferably sulfocationic ones: fine-grained or molded. In PPAs, it is preferable to use catalysts or catalyst modules with large flow cross sections for the vapor stream, in particular catalyst modules with thin layers of fine-grained catalyst (preferably sulfocationionite) limited by metal grids passing reactants and reaction products (s), or molded catalysts with a large particle size (elements).

The simplest way is to obtain predominantly 2-methyl-2-butene and ATPE (with a small admixture of n-pentane and n-pentenes). If it is necessary to obtain 2-methyl-1-butene, 2-methyl-2-butene can be isomerized and 2-methyl-1-butene separated from it by distillation.

If it is necessary to obtain tert-pentenes with practically no admixture of n-pentane and n-pentenes, this is achieved by the catalyzed decomposition of ATPE, from which n-pentane and n-pentenes are distilled off, and subsequent washing from alcohol and rectification.

The use of the invention is illustrated in FIG. 1 and 2 and examples that do not exhaust all the options and it is possible to use other technical solutions, subject to all the signs set forth in claim 1.

In figures 1 and 2, the devices and lines (streams) that perform the same functions, for ease of comparison are denoted by the same numbers. For devices and lines that perform different functions, numbers with the addition of "a" are used for figure 1 and "b" for figure 2.

According to Fig. 1, isopentane is fed into line 10a, including isopentane dehydrogenation and separation of the C ₅ -hydrocarbon fraction from the contact gas, through line 1, and a stream containing predominantly isopentane is recycled through line 11a (hereinafter, together along line 1a). A stream containing predominantly C ₅ isopentane, isopentenes, partially isoprene, and an admixture of hydrocarbons of normal structure is discharged from line 10a from line 10a, and gas, C ₄ hydrocarbons and C ₆ hydrocarbons are also removed (for simplicity, the output is shown by one line 24).

The predominantly C ₅ hydrocarbon stream is fed through line 2 to reactor 20, where pentadienes are hydrogenated and 2-methyl-1-butene is isomerized to 2-methyl-2-butene. Via line 3, hydrogen or a hydrogen-containing gas mixture is supplied to the reactor 20.

From the reactor 20, through line 4, the reaction mixture is fed to an exhaustive distillation column 40. On line 5, a liquid stream is fed from the bottom of column 40 to the top of column 40. It is a conventional distillation column or reactive distillation apparatus (short-circuit catalyst zone is shaded). From the top of column 40 via line 6, steam is supplied from below to column 30a. The distillate of column 30a is fed via line 7a to column 50a or directly to unit 10a via line 8a (hereinafter, along lines 11a and 1a). As a distillate of the column 50a (if used), a stream containing predominantly 3-methyl-1-butene is discharged via line 9a, and bottoms are fed via lines 11a and 1a to unit 10a.

From the bottom column 40, a stream containing predominantly 2-methyl-2-butene with impurities from n-pentane and n-2-pentenes is discharged from line 40 from below. Part of the specified stream output line 13 as a product. The other part along line 14, together with streams of alcohol supplied through line 15 and recycled through line 18 from the distillation column 70, is fed through line 16 to a reactor 60 containing an acidic solid catalyst, preferably sulfocathionite. The oblique dashed arrow indicates the presence of heat removal.

From the reactor 60 via line 17, the reaction mixture is fed to column 70. From the top of column 70, distillate containing predominantly C ₅ hydrocarbons and alcohol is returned via line 18 to reactor 60. A stream containing predominantly ATPE is withdrawn from the bottom of column 70 through line 19.

From the bottom of the column 70, lateral extraction is preferably withdrawn along line 21 to a reinforcing zone (column) 80, from which the ATPE containing stream is returned via line 22 to column 70, and a hydrocarbon mixture with a predominant n-pentane content is withdrawn from above on line 23 and n-2-pentenes.

Possibly lateral extraction on line 21 is not used and a small amount of n-pentane and n-2-pentenes is left in stream 19, which prevents their excessive accumulation in the system of apparatuses 60 and 70. Further, C ₅ hydrocarbons can be distilled from stream 19 in additional column 90 .

Figure 2 shows a variant of the process scheme in which a mixture of predominantly C ₅ isocarbons is fed to the hydroisomerization reactor 20 as line hydrocarbon feedstock. The possible origin of stream 2 is not limited only to the dehydrogenation of isopentane, although such dehydrogenation can be preliminarily carried out similarly to that indicated in FIG. In contrast to FIG. 1, the circuit includes an external (at column 30b) reactor 50b for isomerization of 2-methyl-1-butene to 2-methyl-2-butene. In the reactor 50b through line 8b is supplied lateral from the column 30b. From reactor 50b, the reaction mixture is returned via line 9b to column 30b. A distillate 7 containing predominantly isopentane is withdrawn from the top of the column 30b. It is possible, as an option, its processing similar to that indicated in figure 1.

From the bottom of the column 40, a stream containing predominantly 2-methyl-2-butene with a small admixture of n-pentane and 2-pentenes is withdrawn via line 12. Its subsequent distribution and processing are carried out similarly to that shown in figure 1. Alternatively, it is possible to move the flow in the reactor 60 from the bottom up.

Variants of using the apparatus 80 (at the lateral output of the column 70) or the column 90 are in principle alternative. In reality, either apparatus 80 or column 90 is used.

Figure 3 shows an addition to the schemes of figure 1 and / or figure 2, with the goal (if necessary) of obtaining a mixture of pure tert-pentenes from concentrated ATPE (from streams 19 or / and 26 shown in figure 1 and 2) obtained in the mode when C ₅ hydrocarbons are practically distilled from ATPE.

The ATPE stream is heated and fed via line 28 to a reactor 100 in which a solid ether decomposition catalyst, possibly sulfocationite, is located. The reactor 100 is gas phase, gas liquid or liquid phase; it is preferably provided with a heat supply system (indicated by an oblique arrow). It is also possible that a stream recycled from the bottom of the distillation column 110 via line 31 can also be fed to the reactor 100.

From the reactor 100, through line 29, the effluent is sent to column 110. From the top of column 110, via line 32, a mixture of tert-pentene (s) and alcohol is fed to column 120 to separate the alcohol. Through a line 33 from above, a stream of washing agent, typically water, is supplied to column 120. Bottom of the column 120 through line 34 withdraw a solution of alcohol in a washing agent. Further, the alcohol is preferably distilled off from a washing agent (not shown in FIG. 3).

From the top of the column 120, a washed stream is withdrawn via line 35, which is preferably fed to a distillation column 130. In the process using MTPE, a stream containing dimethyl ether is withdrawn from the column 130 from the top 130 via line 36 and / or 36a, and a mixture of pure tert-pentenes. In the process using ETFE, diethyl ether is formed as an impurity, having a boiling point higher than 2-methyl-1-butene, but lower than 2-methyl-2-butene. Before feeding the mixture into the column, it is possible to conduct isomerization of 2-methyl-1-butene to 2-methyl-2-butene or to purify diethyl ether by other known methods: molecular sieves, a large amount of extractant, etc.

Alternatively, the decomposition of ATPE can be carried out in a distillation apparatus, for which acidic coarse solid catalyst or a catalyst module with large passages for the vapor stream can be placed in column 110 (short-circuit catalyst zones are shown). In this case, a stream with a predominant alcohol content is output via line 31a.

Examples

In the examples, for simplicity, instead of the expression "stream output (supplied) by line number", the expression "stream number" is used, which is understood to be identical.

Example 1

The processing of hydrocarbons C ₅ (isopentane mixed with n-pentane) and methanol is carried out according to figure 1. Column 50a is not used and flow 7a directly (via lines 8a, 11a and 1a) is supplied to assembly 10a. Column 30a functions as a conventional reinforcing distillation column.

At a site 10a, a dehydrogenation catalyst is used and the dehydrogenation temperature is 550-580 ° C. A mixture of predominantly C ₅ hydrocarbons fed to the reactor 20 is isolated from the contact gas. In the reactor 20, a “Ni on a solid support” catalyst is used (Pd on a solid support is possible, the use of which gives practically similar results).

At the stage of ether synthesis, a fine-grained Amberlist-35 sulfocationite catalyst having a static exchange capacity of СОЕ = 5.0 mg.eq./g. Was loaded into reactor 60. It is possible to use other sulfocationic catalysts and catalyst modules, the use of which with appropriate adjustment of the amount of catalyst in the reactor 60 gives similar results in the conversion of 2-methyl-2-butene and the composition of the reaction mixture. The temperature in the reactor 60 is 60-85 ° C.

Table 1 gives a description of the magnitude and composition of the main flows.

Example 2

Processing is carried out similarly to example 1.

Unlike Example 1, column 50a is used to separate stream 7a. 0.9 t / h of distillate containing 96.7% 3-methyl-1-butene and 3.3% isopentane are removed from column 50a.

Example 3

The processing of hydrocarbons C ₅ (initially isopentane) and methanol is carried out similarly to example 1.

In contrast to Example 1, in the middle (or lower) part of the column 30a, a sulfocationic catalyst is located in the form of a catalyst module or large elements providing a sufficiently large passage of the vapor stream. Thus, the column 30a functions as a reinforcing reactive distillation column. This allows for additional isomerization of 2-methyl-1-butene (to 2-methyl-2-butene) remaining in the mixture after reactor 20.

Table 2 gives a description of the magnitude and composition of the main flows. The yield of 2-methyl-2-butene with a stream of 12 and ATPE with a stream of 19 increases by 7-9% rel. compared with example 1.

Example 4

The processing of hydrocarbons C ₅ and methanol is carried out according to figure 2. A mixture of predominantly C ₅ isocarbons, in which isopentane, tert-pentenes, and isoprene, n-pentane and n-pentenes are present as impurities, is sent to the hydroisomerization reactor 20 through line 2. The origin of the mixture is not critical. In particular, it can be obtained based on dehydrogenation, as shown in figure 1. The main difference in processing is that an external isomerization reactor 50b is connected to the column 30b, which performs the distillation function, into which liquid side sampling from the column 30b is fed, and then the reaction mixture from 50b is returned to the column 30b below the sampling point in the reactor 50b.

The amount of lateral extraction and reactor parameters 50b are selected in such a way that additional isomerization of 2-methyl-1-butene to 2-methyl-2-butene is achieved, which is almost the same as that achieved in Example 3.

Sulfocationic catalyst is loaded into reactor 50b. The temperature in the reactor is 55-85 ° C.

The number and composition of flows output along lines 7 and 12 from the connected columns 306/40 are similar to those obtained in Example 3.

Example 5

Processing C ₅ and ethanol is carried out according to figure 2 similarly to example 4. The supply of alcohol (ethanol) increases to 10.0 t / h Unlike Example 4, it is not necessary to completely separate ethanol from ethyl tert-pentyl ether (ETFE) in column 70. 5% of ethanol is left in the ether product (cube number 70 or 90). The output of the ether product is 23.4 t / h, in its composition 22.0 t / h ETFE.

Example 6

A stream of 19.4 t / h containing 99.5% wt. MTPE, 0.5% wt. according to FIG. 3, the dimers of tert-pentenes and tert-pentanol are decomposed in a shell-and-tube reactor 100. Amberlist sulfocationionite (СОЕ = 2.5 mg equivalent / g) is poured into the reactor 100 (in tubes). The temperature in the reactor is 120-130 ° C. MTPE conversion per passage ~ 70%, taking into account recycling along line 31, is close to 100%. Stream 32 is distilled off from column 110, from which methanol is extracted with water. Stream 35 in the amount of 13.1 t / h, containing mainly tert-pentenes and 0.05% dimethyl ether, is fed to the column 130 for distillation from dimethyl ether. A stream containing dimethyl ether is discharged from the top of the column 130. A mixture of pure tert-pentenes (2-methyl-2-butene and 2-methyl-1-butene) containing not more than 0.001% wt. methanol and not more than 0,0005% wt. dimethyl ether.

Claims (9)

1. A method of producing tert-pentene (s) and / or alkyl C ₁ -C ₂ tert-pentyl ether from mixtures of predominantly C ₅ hydrocarbons containing at least tert-pentenes, isopentane and an admixture of pentadiene (s) and alcohol C ₁ -C ₂ , including the interaction of tert-pentene (s) with alcohol C ₁ -C ₂ on a solid acid catalyst and the isolation of products by distillation, characterized in that at least a catalyzed isomerization of 2-methyl-1-butene in 2 is carried out in the initial mixture -methyl-2-butene [possibly in the presence of hydrogen], the resulting mixture is subjected to distillation and vyv DYT containing distillate preferably isopentane and bottoms residue containing mainly 2-methyl-2-butene, of which preferably subjected to area (s) synthesis of ester (s) catalyzed reacted with an alcohol C ₁ -C _2, of the resultant mixture was distilled distillate containing a mixture of unreacted C ₅ hydrocarbons with alcohol, which is then used to obtain the ester (s), preferably returned to the synthesis zone of the ester (s), and a bottoms residue containing C ₁ -C ₂ alkyl-tert-pentyl ether, which selected as Your product and / or is subjected to catalyzed decomposition and a mixture of pure tert-pentenes is isolated by rectification and purification from alcohol. 2. The method according to claim 1, characterized in that a mixture of predominantly C ₅ hydrocarbons obtained by isopentane dehydrogenation is used, and the distillate distilled off after said isomerization is mainly returned to dehydrogenation directly or after distillation from it of a stream containing predominantly 3-methyl- 1-butene. 3. The method according to claim 1, characterized in that in the specified initial hydrocarbon mixture, hydrogenation of pentadiene (s) and isomerization of 2-methyl-1-butene, as well as possibly 3-methyl-1-butene to 2-methyl, are carried out sequentially or simultaneously -2-butene. 4. The method according to claim 1, characterized in that in the specified initial hydrocarbon mixture, pentadiene (s) are hydrogenated and at least 2-methyl-1-butene is hydroisomerized into 2-methyl-2-butene in the presence of a catalyst (s) containing (their) metal (s) selected from (e) from the group consisting of Ni, Pd, Pt in chemically unbound form or in the form of compounds, preferably on a solid support. 5. The method according to claim 1, characterized in that the hydrogenation of pentadienes and / or hydroisomerization of 2-methyl-1-butene to 2-methyl-2-butene in a straight-through liquid hydrocarbon reactor is carried out first, and then 2-methyl isomerization is additionally carried out -1-butene to 2-methyl-2-butene in a distillation mixture on a solid catalyst inside a column reaction-distillation apparatus in a reaction zone located in the part that strengthens the power supply and / or in the external reaction zone connected to the column distillation apparatusits input from the specified reinforcing part of the stream and the output stream. 6. The method according to claim 1, characterized in that the synthesis of alkyl C ₁ -C ₂ tert-pentyl ether is carried out in a direct-flow (s) reaction (s) zone (s) connected (s) with a subsequent distillation column, or / and in the reaction zone with a catalyst located in the strengthening part of the column reactive distillation system relative to the power supply. 7. The method according to claim 5, characterized in that overheating in the specified (s) once-through (s) reaction (s) zone (s) is eliminated by its (their) cooling and / or evaporation of part of the reaction mass and / or recycling possibly cooled part of the output stream to the entrance to the zone (s). 8. The method according to claim 1, characterized in that in the zone (s) of the synthesis of the specified ester, the content of pentane (s) and / or other C ₅ hydrocarbons practically not interacting with alcohol is maintained in an amount of from 5 to 90 wt.% . 9. The method according to claim 1, characterized in that the excess (e) n-pentane and n-pentenes from the distillation zone upon receipt of the specified ether is removed together with ether and a slight admixture of 2-methyl-2-butene, possibly followed by distillation from ether or as a part of lateral selection from the bottom of the distillation zone.

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