RU2329246C1 - Method of obtaining 2-methyl-2-butene from isopentane and method of obtaining isoprene from isopentane - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention pertains to the method of obtaining 2-methyl-2-butene from isopentane, including gas phase dehydrogenation of isopentane in the dehydrogenation zone, extraction of the C₅-fraction from contact gas, mainly consisting of isopentane, tert pentanes, isoprene impurities and other hydrocarbons and obtaining a stream from it, mainly consisting of 2-methyl-2-butene, with use of a liquid phase isomerisation catalyst in a C₅-fraction 2-methyl-1-butene in 2-methyl-2-butene and distillation. The method is characterised by that, the above mentioned C₅-fraction, possibly containing extra piperylene and 2-pentene, directly or after distillation from the larger part of 2-methyl-2-butene, undergoes liquid phase hydroisomerisation in the presence of a solid catalyst, containing group VIII metal(s), capable of simultaneous catalysing hydrogenation of pentadienes, isoprene and possibly, piperylenes, and positional isomerisation of tert pentenes, preferably with subsequent additional isomerisation of 2-methyl-1-butene in 2-methyl-2-butene on a sulfocationite catalyst, and distillation with output of a distillate stream of mainly isopentane, containing not more than 1.0% mass, preferably not more than 0.2% mass of pentadiene(s), which are mainly recirculated in the hydrogenation zone, and output from the lower part of the recirculation stream of mainly 2-methyl-2-butene with impurities of n.pentane and possibly 2-pentenes. The invention also pertains to the method of obtaining isoprene from isopentane, which involves reaction of 2-methyl-2-butene, obtained from gas phase dehydrogenation of isopentane, with hydroperoxide with further conversion of the oxide or products of hydroxylation in isoprene.

EFFECT: obtaining 2-methyl-2-butene and isoprene from isopentane.

13 cl, 8 ex, 2 tbl, 3 dwg

Description

The invention relates to the field of obtaining individual tert.pentenes and obtaining isoprene (2-methyl-butadiene-1,3). More specifically, the invention relates to the field of production of 2-methyl-2-butene and isoprene from isopentane.

The known method [P.A. Kirpichnikov and others. "Album of technological schemes of the main industries of the synthetic rubber industry." L., Chemistry, 1986, p.53-70] obtaining a mixture of predominantly tert.pentenes, including high-temperature gas-phase catalytic dehydrogenation of isopentane, extracting a C ₅ hydrocarbon mixture containing predominantly isopentane and isopentenes from the contact gas, and subsequent separation of the mixture by extractive distillation in the presence of a polar extractant with the release of a stream containing predominantly isopentane returned to dehydrogenation and a stream containing predominantly a mixture of tert pentenes (2-meth il-1-butene and 2-methyl-2-butene).

There is also known a method [P.A. Kirpichnikov et al.] For producing isoprene by high-temperature gas-phase catalytic dehydrogenation of a mixture of tert.pentenes obtained by the above method, in which a mixture of C ₅ hydrocarbons containing predominantly tert.pentenes, isoprene is extracted from the contact dehydrogenation gas and piperylene (pentadiene-1,3), a mixture of pentadienes is extracted from it by extractive distillation in the presence of a polar agent, and then isoprene and piperylene are separated by rectification.

The process of producing isoprene from isopentane, which sequentially uses the above methods, usually referred to as the process of two-stage dehydrogenation of isopentane, is very complicated and expensive.

A known method [patent RU - 2102370 from 01.20.1998] of producing isoprene from isopentane, according to which isopentane is subjected to liquid-phase oxidation mainly in tert-pentine hydroperoxide, which is epoxidized with 2-methyl-2-butene to form 2-methyl-2- oxide butene and tert.pentanol. 2-methyl-2-butene oxide and tert-pentanol are separated by distillation and then 2-methyl-2-butene oxide is converted to isoprene. Tert.pentanol is dehydrated to give a mixture of 2-methyl-2-butene and 2-methyl-1-butene. 2-Methyl-2-butene directed to epoxidation is isolated from this mixture by distillation, and 2-methyl-1-butene is isomerized to 2-methyl-2-butene on a sulfocationite catalyst in the presence of a large amount of alcohol, followed by decomposition of the generatrix (s) ester (s) and then an additional amount of 2-methyl-2-butene is isolated from the reaction mixture.

The specified process is very complicated. One of its significant drawbacks is the low conversion (~ 7%) of isopentane to tert-pentyl hydroperoxide. An attempt to increase the conversion leads to the formation of a large number of by-products due to the oxidation in the isopentane molecules of the secondary carbon atom adjacent to the tertiary carbon atom. The method of isomerization of 2-methyl-1-butene to 2-methyl-2-butene in the presence of alcohol, proposed in Ru - 2102370, leads to the formation of a large number of by-products (in particular, esters) and requires further separation of 2-methyl-2-butene from alcohol and by-products.

A known method [patent Ru - 2170225 from 08/04/1998] joint production of isoprene and monomer with an alkenyl group (isobutene or alkenylbenzene). In this case, isopentane is subjected to catalytic dehydrogenation, a mixture of C ₅ hydrocarbons is extracted from the contact dehydrogenation gas, and then 2-methyl-2-butene is obtained from it using rectification and isomerization of 2-methyl-1-butene to 2-methyl-2-butene, and a stream containing predominantly isopentane and partially unsaturated C ₅ hydrocarbons is returned to the dehydrogenation zone. The secreted 2-methyl-2-butene is then epoxidized with alkyl hydroperoxide to 2-methyl-2-butene oxide, which is further converted to isoprene.

The alkyl hydroperoxide necessary for epoxidation is obtained by liquid-phase oxidation of the corresponding hydrocarbon (isobutane or alkylbenzene). The corresponding alcohol is formed from alkyl hydroperoxide during the epoxidation of 2-methyl-2-butene, the dehydration of which produces a monomer with one alkenyl group: isobutene, styrene, α-methylstyrene.

A significant drawback of the method is that it is designed to process the C ₅ dehydrogenation fraction, which is practically free of pentadienes (see stream 3 in Tables 1-3). In fact, such fractions contain 2.5-3% isoprene and 0.2-0.4% piperylene. When the C ₅ fraction is distilled off of a stream containing predominantly isopentane, it also includes up to 4.5% isoprene, which, when this stream is recycled to the dehydrogenation zone, causes coking of the catalyst. Piperylene, especially trans, is practically inseparable from 2-methyl-2-butene by conventional distillation from almost tangential zeotropy (in the 2-methyl-2-butene stream, its relative volatility with respect to trans-piperylene is only 1.07-1.08 )

Another disadvantage of the method according to patent RU 2170225 is that it does not solve the problem of efficient removal of n. Pentane having almost tangential zeotropy with 2-methyl-2-butene, which leads to excessive accumulation of n. Pentane in the epoxidation or hydroxylation system.

The method is limited to the use for the epoxidation of 2-methyl-2-butene hydroperoxides of hydrocarbons and does not provide for the possibility of using hydrogen peroxide.

We declare:

A method of producing 2-methyl-2-butene from isopentane, including gas-phase dehydrogenation of isopentane in a dehydrogenation zone, extraction from a contact gas of a C ₅ fraction containing mainly isopentane, tert.pentenes, impurities of isoprene and other hydrocarbons, and obtaining from it a stream containing predominantly 2-methyl-2-butene, using liquid phase catalytic isomerization in the C ₅ fraction of 2-methyl-1-butene to 2-methyl-2-butene and rectification, characterized in that said C ₅ fraction, possibly further comprising piperylene and 2-pen tenes, directly or after distillation from the majority of 2-methyl-2-butene, are subjected to liquid-phase hydroisomerization in the presence of a solid catalyst containing metal (s) of group VIII of the periodic system of D.I. Mendeleev, capable of simultaneously catalyzing the hydrogenation of pentadienes, isoprene and possibly piperylene, and the positional isomerization of tert.pentenes, preferably followed by further isomerization of 2-methyl-1-butene to 2-methyl-2-butene on a sulfocationite catalyst, and distillation with the conclusion as distillate a stream of predominantly isopentane containing not more than 1.0 wt.%, preferably not more than 0.2 wt.% of pentadiene (s), which is mainly recycled to the dehydrogenation zone, and mainly 2-methyl-2- is withdrawn from the bottom of the rectification stream butene mixed with N. pentane and possibly 2-pentenes.

As methods contributing to the efficient production of 2-methyl-2-butene from isopentane according to claim 1, we also declare methods in which:

- conduct joint hydrogenation of pentadienes and isomerization of 2-methyl-1-butene in the presence of a sulfocationite catalyst containing the specified (e) metal (s),

- in these zones of isomerization and / or hydroisomerization, an additional amount of saturated hydrocarbon (s), possibly a stream of predominantly isopentane, is added in an amount that provides a concentration of alkanes in the mixture from 50 to 90 wt.%,

- the rectified stream containing predominantly isopentane is subjected to a rectification in which a distillate containing predominantly 3-methyl-1-butene is withdrawn and the bottoms are preferably recycled to the dehydrogenation zone,

- the stream of predominantly 2-methyl-2-butene removed from the bottom of said rectification is further subjected to distillation from dimers, possibly oligomers and resins.

We declare (regardless of the method according to claim 1):

A method of producing isoprene from isopentane, including the gas-phase dehydrogenation of isopentane, extraction from a contact gas of a C ₅ fraction containing predominantly isopentane, tert-pentenes, impurities of isoprene and other hydrocarbons, obtaining a stream of mainly 2-methyl-2-butene from it using liquid phase isomerization 2-methyl-1-butene to 2-methyl-2-butene and rectification, the catalyzed interaction of 2-methyl-2-butene with hydroperoxide and the subsequent conversion of the oxygen-containing (s) compound (s) C ₅ thereof to isoprene, excellent schiysya in that said C ₅ fraction is optionally further containing piperylenes and 2-pentenes, or directly after distillation of the most part of 2-methyl-2-butene was subjected to liquid-phase hydroisomerization in the presence of a solid catalyst containing the metal (s) VIII group of the periodic system D.I. Mendeleev, capable of (e) simultaneously catalyzing the hydrogenation of pentadienes, isoprene and possibly piperylene, and the positional isomerization of tert.pentenes, preferably followed by additional isomerization of 2-methyl-1-butene to 2-methyl-2-b Uten on a sulfation cationite catalyst, and rectification, a stream of predominantly isopentane, preferably recycled to the dehydrogenation zone, is distilled off, and a stream of mainly 2-methyl-2-butene is removed from the bottom of the rectification with a content of not more than 10%, preferably not more than 2%, n. pentane and possibly an impurity of 2-pentenes, in the specified stream, 2-methyl-2-butene is reacted with hydrocarbon hydroperoxide and / or hydrogen hydroperoxide in the presence of a catalyst containing an ac metal active in the above interaction valencies of group IV, V or VI of the periodic system of D. I. Mendeleev, preferably molybdenum, tungsten or titanium, with recirculation of the stream containing predominantly 2-methyl-2-butene, with the outlet of the stream with a high content of n.pentane, and the oxide formed 2-methyl-2-butene and / or its hydroxylation products are converted to isoprene, which is removed from the mixture and the alcohol formed from the hydrocarbon hydroperoxide is possibly dehydrated into the corresponding monovinyl monomer.

As methods contributing to the efficient production of isoprene from isopentane according to claim 8, we also declare methods in which:

- a stream of predominantly 2-methyl-2-butene, containing partially N. pentane, is subjected to catalyzed interaction with hydroperoxide in at least two zones, in one of which the molar predominance of 2-methyl-2-butene over hydroperoxide is maintained, and at least part of the unreacted hydrocarbons is fed into the reaction zone with a molar predominance of hydroperoxide over 2-methyl-2-butene, a stream with a high content of n.pentane is withdrawn, and a stream containing hydroperoxide, reaction products, and possibly a catalyst, which returns Click to the first of these zones,

- in the first zone of interaction of 2-methyl-2-butene with hydroperoxide, the molar ratio of incoming 2-methyl-2-butene and hydroperoxide is maintained from 1.4: 1 to 10: 1, and in the second zone from 0.1: 1 to 0 , 85: 1,

- to interact with 2-methyl-2-butene, hydroperoxide (s) obtained by oxidation of hydrocarbon (s) from the group consisting of isobutane, ethylbenzene, isopropylbenzene, and forming (e) reacting with 2-methyl- 2-butene, the alcohol (s) is preferably dehydrated and isobutene, styrene or a-methylstyrene respectively are obtained, or the alcohol (s) is removed from the reaction mixture and used for other purposes,

- tert-butyl hydroperoxide is used as said hydrocarbon hydroperoxide, and additional isoprene is obtained from tert-butanol formed by reaction with 2-methyl-2-butene by reacting it with formaldehyde and decomposing the resulting intermediates,

- tert-butanol is extracted from the reaction mixture and additional isoprene is obtained from it and possibly isobutene using its (their) interaction with formaldehyde and decomposition of intermediates,

- 2-methyl-2-butene hydroxylation products are obtained by contacting it with an aqueous and / or alcoholic solution of hydrogen peroxide in the presence of a water-soluble and / or solid catalyst containing variable metal valency (s) selected from the group consisting of molybdenum, tungsten titanium

- the products of hydroxylation and / or dihydroxylation are subjected to catalytic dehydration directly in the resulting aqueous and / or aqueous-alcoholic solution.

In the proposed method, various options (processes) for the thermocatalytic dehydrogenation of isopentane can be used, in particular, the known dehydrogenation processes with a suspended aluminum-chromium catalyst, with a stationary layer of an aluminum-chromium or platinum-containing catalyst, and possibly other isopentane dehydrogenation processes in which isopentane is converted mainly into tert-pentenes.

For the simultaneous hydrogenation of alkadienes in the C ₅ fraction of the dehydrogenation and hydroisomerization of 2-methyl-1-butene to 2-methyl-2-butene, any catalysts suitable for the selective hydrogenation of alkadienes without significant hydrogenation of tert-alkenes can be used.

For the isomerization of 2-methyl-1-butene to 2-methyl-2-butene, any catalysts capable of moving a double bond in tert-pentene molecules without destroying the carbon skeleton, in particular cationic (usually sulfocationic) catalysts or catalysts, can also be used. containing metals of variable valency, of which the catalysts containing nickel, palladium, copper or platinum on a solid support are most known and used in industry.

The process of preferential hydrogenation of alkadienes (with concomitant isomerization of 2-methyl-1-butene) may precede the process of isomerization of 2-methyl-1-butene to 2-methyl-2-butene on cation exchange resin (s) or can be carried out after said isomerization, or these processes may be combined in one reaction zone.

As reactors for isomerization, various apparatuses can be used with vertical (top to bottom or bottom to top), horizontal or other way of moving the liquid and its contact with the catalyst. For hydrogenation and hydroisomerization, vertical apparatuses with bubbling a hydrogen-containing stream through a liquid (and a catalyst) or irrigation-type apparatuses with a system for maintaining a given hydrogen pressure can be used. One of the distillation zones may precede hydroisomerization and below it a stream containing predominantly 2-methyl-2-butene.

As catalysts for epoxidation and / or hydroxylation of 2-methyl-2-butene can be used various known catalysts containing molybdenum, tungsten and other metals effective in these processes.

The preparation of isoprene from 2-methyl-2-butene oxide or alcohol (s) obtained by hydroxylation and / or dihydroxylation of 2-methyl-2-butene can be carried out by decomposition with known selective catalysts, for example, in the presence of borophosphate catalysts or catalysts containing strontium compounds or other acidic catalysts. It is possible to obtain isoprene from C ₅ glycols by liquid-phase or vapor-liquid dehydration catalyzed by strong acid (H ₂ SO ₄ , H ₃ PO ₄ , etc.) or strongly acid cation exchange resin. 2-Methyl-2-butene oxide for conversion to isoprene can be initially or in a joint process converted to alcohol (s) with a C ₅ and / or C ₅ unsaturated alcohol followed by its dehydration.

The use of the proposed methods is illustrated in figures 1-3 and examples. These figures and examples do not exhaust all possible options and other technical solutions can be used provided that, respectively, claim 1 and / or claim 8 of the claims.

In the figures, the symbols used: SP - Isopentane, NP - n-pentane, 2M2B - 2-methyl-2-butene, C ₄ - hydrocarbons, C _4, C ₅ - hydrocarbons C _5, C _{6 +} - C ₆ hydrocarbons, and higher boiling hydrocarbons, KM - compressor, СО - separator-settler.

According to Fig. 1, a stream containing predominantly isopentane is supplied via line 1. The specified stream together with the recirculated stream 15 (IP + stream) is heated, evaporated and fed via line 2 to the dehydrogenation unit (UD). From the UD output gaseous stream 3, which is compressed in the compressor CM and is fed through line 4 to the selected node C ₅ -smesi (SHI node). From the hydrocarbon stream, lines of gas, mainly C ₄ hydrocarbons and C ₆₊ hydrocarbons, are taken out along lines 5, 6 and 7, respectively. Line 8 displays a stream containing predominantly C ₅ hydrocarbons, which is fed directly (line 8a) to reaction zone P or preliminarily fed to a K-1 distillation column (line 8b), where it is distilled from most of the contained 2-methyl-2 -butene (stream 10), sediment from water in CO and through line 9 (hereinafter 11) is fed into zone R.

Zone P contains catalyst (s) having (e) activity in the reactions of hydrogenation of alkadiene and hydroisomerization of alkenes with a change in the position of the double bond. The C ₅ hydrocarbons in zone P are preferably maintained in a liquid state. From below, hydrogen or a hydrogen-containing gas mixture is fed through zone 12 through a switchgear through line 12. From the zone P, a gas stream including unreacted hydrogen is discharged from above via line 13. Part of the stream 13 can be recycled to the entrance to zone P along line 13b.

From the upper part of zone P, a hydrocarbon stream 14 is withdrawn, which is fed to the distillation zone K-2. As a distillate, a stream 15, containing mainly isopentane, is recycled from zone K-2, which is recycled through line 15 to the UD unit.

From the bottom of zone K-2, a stream containing mainly 2-methyl-2-butene is discharged along line 16, which is then discharged through line 16a or fed to line I through line 16b, where it is distilled from dimers and other heavy impurities (line 18) and discharged along line 17 (hereinafter, along line 10a), possibly connecting to stream 10.

2, the dehydrogenation of isopentane in a node selection LE and C ₅ hydrocarbons in hydrocarbon -smesi node is carried out as shown in Figure 1.

In contrast to figure 1, the hydroisomerization of 2-methyl-1-butene and the hydrogenation of pentadienes is carried out in an irrigation type reactor P-1 containing a catalyst with metal (s) active (s) for these reactions.

A liquid hydrocarbon mixture (pot.8 and possibly pot.20g) is fed to P-1 from above through a switchgear. Hydrogen is supplied in a small amount along line 9 (hereinafter 9a, 9b), and its pressure in P-1 is regulated.

From P-1 below, along line 10, the reaction mixture is fed from above to the P-2 reactor (possibly with a stream 20c) through a switchgear. P-1 contains a sulfocationite catalyst. Bottom R-2 output the liquid stream 11, which is fed into the distillation column K-1.

From stream K-1 a stream 12 is withdrawn from below, containing mainly 2-methyl-2-butene. It is then taken out along line 12a or through line 12b to the apparatus And for distillation from heavy impurities. These impurities are discharged along line 15, and the distilled stream containing predominantly 2-methyl-2-butene is discharged along line 16. Perhaps streams 12a and 16 are connected and discharged through line 17.

On top of K-1, the gas stream is condensed and layered in a CO separator. The bottom layer is the water layer. The hydrocarbon stream 14 is mainly recycled to the UD through line 14a (hereinafter 20, 20a, 20b) and / or through line 14b is fed to a K-2 column, from which a distillate containing predominantly 3-methyl-1-butene is withdrawn from above from line 18 and a stream containing predominantly isopentane is withdrawn from below along line 19, which is recycled mainly in UD (along lines 20, 20a, 20b).

According to figure 3, the processing is carried out by dehydrogenation of isopentane (IP) in the site of UD, followed by separation of the C ₅ mixture from the contact gas of dehydrogenation in the site of the UVS. Next, the C ₅ mixture is processed in a hydroisomerization unit (and possibly additional isomerization) and rectification (UGIR unit) as shown in FIG. 1 or FIG. 2.

A stream 10 is isolated which contains predominantly 2-methyl-2-butene (2M2B), which is sent to react with hydroperoxide, and a stream 9, which contains predominantly isopentane, which is recycled to the UD unit.

Stream 10 in FIG. 3 corresponds to stream 10a in FIG. 1 or stream 17 in FIG. 2; stream 9 in figure 3 corresponds to stream 15 in figure 1 or stream 20 in figure 2.

Stream 10 is sent to the processing unit hydroperoxide (OGP). It is possible that stream 10 is preliminarily mixed with a hydroperoxide stream (stream 11a), the mixture is fed to column K, and light hydrocarbons are distilled off via line 12 (for example, isobutene using tert-butyl hydroperoxide). On line 13, the mixture distilled from light impurities is fed to the UCP.

In UCP, flows of unreacted 2-methyl-2-butene 14a and 18 and stream 17 from the DHA unit (if used) are also recycled.

A stream of unreacted 2M2B via line 14 and a stream 15, containing mainly products resulting from the interaction of 2M2B with hydroperoxide, are removed from the OGP unit. The stream 14 is partially (mainly most of it is returned to the UCP through line 14a, and partially it is fed to the additional processing unit with hydroperoxide via line 14b).

The initial stream containing hydroperoxide, enters the process through line 11. A part of it is fed through line 11b to the DOGP unit.

A stream containing n.pentane (NP) and possibly light components, for example, isobutane (IB), is withdrawn from DOGP along line 16. Line 17 displays a stream containing predominantly hydroperoxide and the products of its interaction with 2M2B, which is fed to the OGP unit.

In the flows supplied to the UCP, the molar predominance of 2M2B over hydroperoxide is supported in total. In the flows supplied to the DHA, the molar predominance of hydroperoxide over 2M2B is supported in total.

Stream 15 from the UCP is fed to the separation zone of the ROGP.

2M2B oxide and possibly tert-butanol are withdrawn from ROGP through line 19, or 2M2B oxide and / or C ₅ alcohols are removed through line 20. A line containing alcohol formed from hydrocarbon hydroperoxide (e.g. methylphenylcarbinol, dimethylphenylcarbinol or tert-butanol), or water, further discharged through line 21b, is discharged along line 21 (further 21a).

Stream 19 is fed to a thermocatalytic dehydration and separation unit (TCD), from which at least a stream of isoprene, IPR (line 23), a stream of water (stream 24), by-products (total stream 25) and possibly isobutene stream (stream 26) are withdrawn.

Stream 20 is fed to the preparation, liquid-phase dehydration and separation unit (ZhDR unit), from which at least isoprene stream (stream 27), water stream (stream 28) and by-products (total stream 29) are withdrawn.

Stream 21a, containing alcohol formed from hydrocarbon hydroperoxide, is possibly fed to the alcohol dehydration and separation unit (DSD), from which at least MOM monoolefin hydrocarbon (monomer) is withdrawn through line 30, water through line 31, and total (conditionally) by-products through line 32.

If stream 21a contains tert-butanol, it may be fed via line 21c to obtain additional isoprene by reaction with formaldehyde and subsequent decomposition of intermediates into isoprene.

EXAMPLES

Example 1

Obtaining 2-methyl-2-butene from isopentane is carried out according to figure 1

Isopentane dehydrogenation in UD is carried out in a system with a fluidized bed of an aluminum-chromium catalyst at 530-540 ° C. 1100 kg of “fresh” isopentane (c <0.5%) n. Pentane and a recycle stream are fed. Isolation of C ₅ -smesi contact gas (SHI) is carried out by absorption of high-boiling hydrocarbon solvent hydrocarbons followed by rectification distillation stream containing mainly C ₄ hydrocarbons, and then distilled-mixture of C ₅ C ₆ - and higher boiling hydrocarbons.

C. _5-mixture (pot.8) is subjected to distillation in column C-1 from 2-methyl-2-butene (contaminated with n.pentana and possibly pentenes-2) that is outputted via line 10. The distillate (pot.9) after water sedimentation is fed to the hydroisomerization reactor P containing the catalyst "Ni on kieselguhr" (~ 30% wt. Ni). From below, a stream containing hydrogen is fed through the switchgear to the “P”, part of which, after exiting the “P”, is recycled to the inlet.

The hydroisomerizate from "P" through line 14 is fed to a distillation column 2. As a distillate, a stream 15, containing mainly isopentane, which is recycled in UD, is withdrawn. From below, stream 16, containing predominantly 2-methyl-2-butene, is connected, which is connected to stream 10 and discharged along line 10a. In the reactor R, a temperature of 25 ° C. is maintained, a load of 1.1 kg of liquid / kg of catalyst per hour. The total conversion of 2-methyl-1-butene to 2-methyl-2-butene is 89.5%. The main hydrocarbon streams are given in table 1.

The result is 839 kg / h of a stream (10a) containing predominantly 2-methyl-2-butene (97.3%) mixed with N. pentane (1.7%), 2-pentenes (0.6%), 2 methyl 1-butene (<0.1%) and piperylene (0.3%). 2145 kg / h of a stream containing predominantly isopentane (95.6%) with an admixture of 0.3% N. pentane and 4% pentenes, less than 0.1% isoprene is returned to dehydrogenation.

In the column K-1 75 theor. plates, reflux number 5, in the column K-2 70 theor. plates, reflux number 4.5.

Table 1
for example 1 Hydrocarbons T bale, ° C Streams,% wt Pot 1 Pot 8 Pot 9 = 11 Pot 10 Pot 14 Pot 15 Pot 16 Pot 10a Isopentane 27.8 99.5 67.0 81.3 - 83,4 95.6 - - N. pentane 36.1 0.5 0.8 0.6 1,5 0.6 0.3 2.0 1.7 3-M-1-butene 20.1 1.4 1.7 - 1.7 1.9 - - 1-pentene 30,0 0.3 0.4 - 0.3 0.4 - - 2-pentenes 36.3 and 36.9 0.4 0.4 0.55 0.4 0.3 0.6 0.6 2-M-1-butene 31,2 9,4 11.6 - 1,2 1,1 0.1 ≤0.04 2-M-2-butene 38.6 18.3 1,2 97.4 12,4 0.3 97.3 97.32 Isoprene 34.1 2,3 2,8 0.05 ≤0.1 ≤0.1 - ≤0.04 Piperylene 42.0 and 44.2 0.1 - 0.5 - - - 0.3 Dimers > 100 - - - - - - - Weight kg / h 1100 2984 2456 528 2456 2145 311 839

Example 2

The preparation of 2-methyl-2-butene is carried out similarly to that indicated in Example 1. In contrast to Example 1, a sulfocationite catalyst containing 0.7% by weight of palladium is used as a hydroisomerization catalyst. The reactor is maintained at a temperature of 30 ° C, the load on the catalyst is 0.7 kg of liquid / kg of catalyst per hour. Unlike Example 1, isopentane increase 2 times higher, but there is a C ₁₀ dimer formation in an amount of 0.2% of the total amount of liquid. From them, the product is reevaporated in the apparatus “I”.

The result is 862 kg / h of a stream containing predominantly 2-methyl-2-butene (97.1%) mixed with n. Pentane (2.1%), 2-pentenes (0.5%), 2-methyl- 1-butene (0.1%) and piperylene (0.3%).

2121 kg / h of a stream containing predominantly isopentane (95.3%) mixed with n. Pentane (0.35%), pentenes (4.3%), less than 0.05% isoprene is returned to dehydrogenation.

Example 3

Obtaining 2-methyl-2-butene from 1100 kg / h of isopentane (with 0.5% N. pentane) is carried out according to figure 2. The dehydrogenation of isopentane and the separation of the C ₅ mixture is carried out similarly to that described in Example 1. As a hydroisomerization catalyst, palladium (1.2 wt.%) On alumina is used in the reactor R-1, and fine-grained sulfocationite is used in the reactor R-2 (for isomerization) Amberlist-35. In P-1, the temperature is 35-40 ° C, hydrogen pressure is 3.5-4.0 ata, in P-2 it is 25 ° C. The load on the catalyst in R-1 is 2.0 kg / kg cat. Hour, in R-2 - 6.5 kg / kg cat. Hour.

In the column K-1 80 theor. plates, reflux ratio 5. Characteristics of the main hydrocarbon streams are given in table 2

The result is 793 kg / h stream (pot.17) containing 98.2% 2-methyl-2-butene, 1.3% N. pentane, 0.5% N. Pentenes, ≤0.05% piperylene ( no isoprene) and a dehydrogenation stream is recirculated (sweat 14) containing 94.1% isopentane, 0.7% n. pentane, 1.9% 3-methyl-1-butene, 0.8% n. pentenes , 2.6% tert. Pentenes, ≤0.1% isoprene.

Example 4

The preparation of 2-methyl-2-butene from 1100 kg / h of isopentane (with 0.5% n. Pentane) is carried out similarly to example 3. In contrast to example 3, the nickel on kieselguhr catalyst (30% nickel) is used in reactor R-1 ), in the R-2 reactor molded in the form of rings (diameter 3-5 mm, length 4-6 mm) KIF type catalyst. In P-1, the temperature is 20-25 ° C, hydrogen pressure is 3.3-3.5 atm, in P-2 the temperature is 35-40 ° C. The load on the catalyst in R-1 is 1.5 kg of liquid / kg of catalyst, in R-2 - 2 kg of liquid / kg of catalyst.

The compositions of the flows are close to those indicated in Table 2.

Example 5

Obtaining 2-methyl-2-butene from 1100 kg / h of isopentane (with 0.5% N. pentane) is carried out similarly to that specified in example 3 (Fig.2). In contrast to Example 3, the distillation stream 14, before being recycled to dehydrogenation, is rectified in a K-2 column having an efficiency of 80 theory. plates at a specific reflux ratio (ratio of reflux stream to feed stream) 3.9.

~ 42 kg / h of a stream containing 98% 3-methyl-1-butene and ~ 2% isopentane (other pentenes less than 0.03%) are removed from K-2 as a distillate. 2146 kg / h of a stream containing 95.8% isopentane, 0.7% n pentane, ~ 3.4% pentenes and ≤0.1% isoprene are removed from the cube and recycled to dehydrogenation (see Table 2).

table 2
to examples 3-5 Hydrocarbons Streams, wt% (to examples 3-4) Streams,% wt. For example 5 Pot 1 Pot 2 Pot 8 Pot 10 Pot 11 Pot 12 Pot 14 Pot 17 Pot 18 Pot 19 Isopentane 99.5 95.95 67.0 68.5 68.5 - 94.1 - 2.0 95.75 N. pentane 0.5 0.6 0.7 0.8 0.8 1.3 0.7 1.3 - 0.7 3-M-1-butene 1.3 1.4 1.4 1.4 - 1.9 - 97.98 ≤0.05 1-pentene 0.2 0.3 0.3 0.3 - 0.3 - - 0.3 2-pentenes 0.2 0.4 0.4 0.4 0.5 0.3 0.5 - 0.5 2-M-1-butene 1.4 9,4 6.9 2.0 - 2.2 - ≤0.02 2.2 2-M-2-butene 0.3 18.2 21.6 26,4 97.75 0.4 98.15 - 0.4 Isoprene 0.05 2,3 ≤0.1 ≤0.08 - ≤0.1 - - ≤0.1 Piperylene - 0.3 ≤0.01 ≤0.01 ≤0.05 - ≤0.05 - - Dimers - - - 0.1 0.4 - - - - Weight kg / h 1100 3288 2984 2984 2984 796 2188 793 ~ 42 2146

Example 6

Obtaining isoprene from isopentane and simultaneously isobutene from isobutane is carried out according to Fig.3. In this case, isopentane dehydrogenation and obtaining a C ₅ mixture are carried out similarly to that specified in example 1, and the production of 2-methyl-2-butene from a C ₅ mixture is similar to that indicated in example 3.

796 kg / h of a stream containing 98.2% 2-methyl-2-butene, 1.3% N. pentane, 0.5% other pentenes (mainly N. pentenes), ≤0.05% piperylene, served on interaction with hydroperoxide tert.butyl.

The tert-butyl hydroperoxide stream, GPTB, containing 70% GPTB (1001.6 kg / h), 10% tert-butanol (143.1 kg / h) and 20% isobutane, is fed through line 11. Most of it (line 11a ) are connected to the 2M2B stream (line 10), isobutane is distilled off from the stream in the column K, and the bottom residue (pot.13) is fed to the OGP unit. The OGP also serves stream 18 (2M2B) from the separation unit ROGP and stream 17 from the node DOGP. In total, the molar ratio of 2M2B and GPTB = 2.5: 1 and a temperature of 90-110 ° C are maintained in the flows supplied to the OGP. In UCP, there is an almost complete conversion of GPTB.

Unreacted 2M2B is distilled off and partially recycled to the OGP via line 14a, partially sent to the DOGP unit through line 14b. A portion of stream 11 is supplied to DOGP through line 11b. A molar ratio of 2M2B: GPTB = 0.4: 1 and a temperature of 85-100 ° C are maintained at DOGP.

Molybdenum naphthenate at a concentration of 0.05% is used as a catalyst in OGP and DHA.

A stream 16 containing N. pentane and isobutane is distilled off from DHPA, and a stream 17 is supplied to the UCP.

From OGP output stream 15, containing mainly 2M2B oxide and tert-butanol, which is fed to the separation unit ROGP. From ROGP, a mixture of 2M2B oxide and tert.butanol is fed to a TCDD thermocatalytic dehydration and separation unit containing a dehydration catalyst.

658 kg / h of isoprene (stream 22) and 730 kg / h of isobutene (stream 21), water (stream 22) and by-products (conditionally stream 23), including 70 kg / h methyl isopropyl ketone.

Example 7

Obtaining isoprene from isopentane and simultaneously styrene from ethylbenzene is carried out according to Fig.3. Isopentane dehydrogenation and preparation of a C ₅ mixture are carried out similarly to that described in Example 1, and the production of 2-methyl-2-butene (2M2B) from a C ₅ mixture is carried out similarly to that specified in Example 3. 796 kg / h of a stream containing 98.2% 2-methyl-2-butene, 4.3% N. pentane, 0.5% other pentenes, ≤0.05% piperylene, are fed into reaction with ethylbenzene hydroperoxide (HPEB).

A stream containing 35% HPEB (1525 kg / h), 60-63% ethylbenzene (EB) and 2-5% methylphenolcarbinol (mixed with acetophenone) is fed through line 11. A portion of the stream (~ 50-60%) is fed through line 11a in the UCP unit, and the other part along the line 11b is fed to the OGP unit.

Part of unreacted 2M2B from impurities is distilled off via line 14. Most of stream 14 through line 14a is recycled to the OGP unit, and a smaller part containing ~ 25 kg / h of pentane is fed via line 14b to the DOC unit.

A stream 16 with a high content of n pentane is distilled off from DHA and a liquid stream 17 is fed, which is fed to the OGP. The complex obtained by the interaction of molybdenum with HPEB and ethanol is used as a catalyst in OGP and DHA. On the feed (s), the GCP support a total molar ratio of 2M2B and HPEB 4: 1; on submission (s) in the DOGP - their ratio is 0.3: 1. The temperature in the OGP is 100-110 ° С, in the DOGP - 90-100 ° С.

The liquid stream 15 from the OGP is subjected to separation in the site ROGP. From ROGP, stream 18 (mainly 2M2B) is recycled to the OGP, stream 20, containing predominantly 2M2B oxide, stream 21, containing predominantly methylphenylcarbinol, DMF, and stream 22 (mainly ethylbenzene), preferably directed to oxidation to produce hydroperoxide.

2M2B oxide is subjected to liquid-phase isomerization into unsaturated C ₅ alcohol and dehydration to produce isoprene (pot. 27) in the ZhDR unit at 160-180 ° С.

In stream 21, DMF is dehydrated in the presence of an acidic solid catalyst and styrene is withdrawn through line 30 (conversion selectivity 97-98%).

The result is ~ 660 kg / h of isoprene and ~ 1115 kg / h of styrene.

Example 8

Obtaining isoprene from isopentane is carried out according to figure 3. The dehydrogenation of isopentane and the preparation of a C ₅ mixture are carried out analogously to Example 1; the preparation of 2-methyl-2-butane (2M2B) from a C ₅ mixture is carried out analogously to Example 3.

Hydrogen peroxide is used as hydroperoxide for interaction with 2M2B, which is supplied to the process (line 11) as an aqueous solution with a molar amount of hydrogen peroxide in a ratio of 2M2B from 1: 1 to 1.2. The 2M2B stream (sweat 10) and part of the hydrogen peroxide solution (sweat 11a) are supplied to the OGP unit (the rest of the hydrogen peroxide solution is supplied via line 11b to the DOGP unit), and the hydrogen peroxide solution is carefully dispersed into the OGP and possibly in the DGP .

The catalyst used is mainly titanium on a solid porous support containing silicon. The total molar ratio of 2M2B and H ₂ O ₂ in the introduced streams is 5: 1 in OGP, and 0.3: 1 in OGP. The temperature in the OGP is 80-95 ° C, in the DOGP - 75-90 ° C.

After 2M2B distillation, the resulting hydro- and dihydroxylation products in the ROGP unit are fed in an aqueous solution through line 20 to the ZhDR unit, where in the presence of a strong strongly acid catalyst (sulfocationionite) they are dehydrogenated with isoprene distillation.

670 kg / h of a stream containing predominantly isoprene are discharged via line 27.

Claims (13)

1. A method of producing 2-methyl-2-butene from isopentane, including gas-phase dehydrogenation of isopentane in a dehydrogenation zone, extraction of a C ₅ fraction from the contact gas, containing mainly isopentane, tert-pentenes, impurities of isoprene and other hydrocarbons and obtaining a stream from it, containing predominantly 2-methyl-2-butene, using liquid phase catalytic isomerization in the C ₅ fraction of 2-methyl-1-butene to 2-methyl-2-butene and rectification, characterized in that the said C ₅ fraction is optionally further containing piperylene and 2-ne tene, directly or after distillation from most of 2-methyl-2-butene, is subjected to liquid-phase hydroisomerization in the presence of a solid catalyst containing metal (s) of group VIII of the Periodic Table of D.I. Mendeleev, capable of (e) simultaneously catalyzing the hydrogenation of pentadiene, isoprene and possibly piperylene, and the positional isomerization of tert-pentenes, preferably followed by further isomerization of 2-methyl-1-butene to 2-methyl-2-butene on a sulfocationite catalyst, and distillation with withdrawal as a distillate a stream of predominantly isopentane containing not more than 1.0 wt.%, preferably not more than 0.2 wt.% of pentadiene (s), which is mainly recycled to the dehydrogenation zone, and mainly 2-methyl-2- is removed from the bottom of the rectification stream butene mixed with N. pentane and possibly 2-pentenes. 2. The method according to claim 1, characterized in that the co-hydrogenation of pentadienes and the isomerization of 2-methyl-1-butene is carried out in the presence of a sulfocationite catalyst containing the specified metal (s). 3. The method according to claim 1, characterized in that in these zones of isomerization and / or hydroisomerization, an additional amount of saturated hydrocarbon (s) is added, possibly a stream of predominantly isopentane, in an amount providing an alkane concentration in the mixture of from 50 to 90 wt. .%. 4. The method according to claim 1, characterized in that the rectified stream containing predominantly isopentane is subjected to a rectification in which a distillate containing predominantly 3-methyl-1-butene is withdrawn and the bottoms are preferably recycled to the dehydrogenation zone. 5. The method according to claim 1, characterized in that the stream of predominantly 2-methyl-2-butene removed from the bottom of said rectification is further subjected to distillation from dimers, possibly oligomers and resins. 6. A method of producing isoprene from isopentane, including gas-phase dehydrogenation of isopentane, extracting from the contact gas a C ₅ fraction containing predominantly isopentane, tert-pentenes, impurities of isoprene and other hydrocarbons, obtaining from it a stream of mainly 2-methyl-2-butene using liquid-phase isomerization of 2-methyl-1-butene to 2-methyl-2-butene and rectification, the catalyzed interaction of 2-methyl-2-butene with hydroperoxide and the subsequent conversion of the oxygen-containing compound (s) C ₅ thereof (s) into isoprene, excellent yuschiysya in that said C ₅ fraction is optionally further containing piperylenes and 2-pentenes, or directly after distillation of the most part of 2-methyl-2-butene was subjected to liquid-phase hydroisomerization in the presence of a solid catalyst containing the metal (s) VIII of the Periodic System D.I. Mendeleev, capable of (e) simultaneously catalyzing the hydrogenation of pentadienes, isoprene and, possibly, piperylene and positional isomerization of tert-pentenes, preferably followed by additional isomerization of 2-methyl-1-butene to 2-methyl-2- butene on a sulfocationic catalyst, and rectification, a stream of predominantly isopentane, preferably recycled to the dehydrogenation zone, is distilled off, and a stream of predominantly 2-methyl-2-butene is removed from the bottom of the rectification with a content of not more than 10%, preferably not more than 2%, n. pentane and possibly with an impurity of 2-pentenes, in the said stream, 2-methyl-2-butene is reacted with hydrocarbon hydroperoxide and / or hydrogen hydroperoxide in the presence of a catalyst containing metal per group valencies of IV, V or VI group of the Periodic Table of D. I. Mendeleev, preferably molybdenum, tungsten or titanium, with recirculation of a stream containing predominantly 2-methyl-2-butene, with a stream outlet with a high content of n.pentane, and the resulting oxide 2-methyl-2-butene and / or its hydroxylation products are converted to isoprene, which is removed from the mixture and the alcohol formed from the hydrocarbon hydroperoxide is possibly dehydrated into the corresponding monovinyl monomer. 7. The method according to claim 6, characterized in that the stream of predominantly 2-methyl-2-butene, containing partially n. Pentane, is subjected to catalyzed interaction with hydroperoxide in at least two zones, in one of which the molar predominance of 2-methyl- 2-butene over hydroperoxide, and at least part of the unreacted hydrocarbons is fed into the reaction zone with a molar predominance of hydroperoxide over 2-methyl-2-butene, a stream with a high content of n.pentane is removed and a stream containing hydroperoxide, the reaction products and Possible catalyst which is recycled to the first of said zones. 8. The method according to claim 7, characterized in that in the first zone of interaction of 2-methyl-2-butene with hydroperoxide, the molar ratio of incoming 2-methyl-2-butene and hydroperoxide is maintained from 1.4: 1 to 10: 1, and in the second zone, from 0.1: 1 to 0.85: 1. 9. The method according to claim 6, characterized in that for the interaction with 2-methyl-2-butene, hydroperoxide (s) obtained by oxidation of the hydrocarbon (s) from the group consisting of isobutane, ethylbenzene, isopropylbenzene and forming ( f) when it interacts with 2-methyl-2-butene, the alcohol (s) are preferably dehydrated and isobutene, styrene or α-methylstyrene are respectively obtained, or the alcohol (s) is removed from the reaction mixture and used for other purposes. 10. The method according to claim 6, characterized in that tert-butyl hydroperoxide is used as said hydrocarbon hydroperoxide, and additional isoprene is obtained from tert-butanol formed by reaction with 2-methyl-2-butene by reacting it with formaldehyde and decomposing the resulting intermediates. 11. The method according to claim 6, characterized in that tert-butanol is extracted from the reaction mixture and additional isoprene is obtained from it and possibly isobutene using its (their) interaction with formaldehyde and decomposition of intermediates. 12. The method according to claim 6, characterized in that the products of hydroxylation of 2-methyl-2-butene are obtained by contacting it with an aqueous and / or alcoholic solution of hydrogen peroxide in the presence of a water-soluble and / or solid catalyst containing variable valency metal (s) selected (e) from the group comprising molybdenum, tungsten, titanium. 13. The method according to claim 10, characterized in that the products of hydroxylation and / or dihydroxylation are subjected to catalytic dehydration directly in the resulting aqueous and / or aqueous-alcoholic solution.

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