RU2131866C1 - Method of preparing alkyl-tert-alkyl ethers or mixtures thereof - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: method of preparing alkyl-tert-alkyl ethers or mixtures thereof with hydrocarbons and/or alcohols comprises contacting hydrocarbon mixtures containing at least tertiary alkenes and non-tertiary alcohol(s) in the presence of acid catalysts in two or more consecutive reaction zones completely of preferably in liquid state with streams cooled and with optional distillation of unreacted hydrocarbons and recuperation of alcohol(s) therefrom. Number of reaction zones and amount of catalyst in each zone and/or specific volumetric stream feed rate are such that temperature rise in each reaction zone is not higher than 40 C, preferably 25 C. EFFECT: simplified and accelerated process. 9 cl, 3 dwg, 13 ex, 3 tbl

Description

 The invention relates to the field of production of high octane components. In particular, the invention relates to the field of production of alkyl tert-alkyl esters or mixtures containing alkyl tert-alkyl esters.

 A known method of producing alkyl tert-alkyl ethers, in particular methyl tert-butyl ether, by contacting hydrocarbon mixtures containing tertiary alkenes, and alcohols with acidic catalysts, for example, sulfocationion exchangers in flow reactors [1]. The disadvantage of this method is the need for a large molar excess of alcohol with respect to tert-alkene and the need for complex recovery of alcohol from a stream containing the target ether. (SU 1367854 A3, 01/15/08).

 A known method of producing methyl tert-alkyl esters from hydrocarbon mixtures and alcohol in the apparatus of the reactive distillation type. The disadvantage of this method is the relative complexity of the necessary equipment and the need to use a special form and size catalyst with special gas-hydrodynamic properties (RU 1037632 C, 04.01.88).

Closest to our proposed method is the patent according to which the isobutylene-containing C ₄ fraction and methanol are contacted in the liquid phase in the presence of macroporous sulfocationionite in the H-form in two reaction zones with subsequent separation of the reaction mixture and isolation of the target product, and contacting is carried out at the molar ratio of methanol: isobutylene 0.90-0.99: 1 and maintaining the degree of conversion of isobutylene in the first reaction zone of 80-90% and the temperature in the second reaction zone of 20-40 ^o C, (RU 2032657 C1, 04/10/95).

The disadvantages of the method are the excessive concentration of the conversion of tert-alkene (isobutylene) in the first reaction zone and the very low reaction rate in the second reaction zone at the stated temperature of 20-40 ^o C. With such a high (up to 90%) conversion in one reaction zone, it is difficult to avoid overstating temperature and as a result, destruction of the catalyst and formation of by-products respectively, in particular when used in hydrocarbon mixtures as starting C ₄ - and C ₅ fraction of the pyrolysis gasoline and the dehydrogenation in which with tvetstvenno concentration of isobutylene and tert-pentenes reaches 40-60% and 30-45%. In the description of the patent [1], only one technical solution is proposed for the removal of reaction heat - the use of tubular reactors with a cooling jacket, in particular shell-and-tube reactors. Such devices are very complex and expensive and it is difficult to obtain uniform distribution of flow through the tubes in them. The use in this case of simpler, for example adiabatic reactors in the method [1] is practically impossible due to a sharp increase in temperature (up to 120 ^o C).

We propose a method for producing alkyl tert-alkyl esters or mixtures thereof with hydrocarbons and / or alcohols by contacting mixtures of hydrocarbons containing at least tertiary alkenes and non-tertiary alcohol (s) in the presence of acid catalysts in two or more reaction zones completely or predominantly in a liquid state with intermediate cooling of the streams and possible subsequent distillation of unreacted hydrocarbons and recovery of alcohol (s) from them, which consists in using such a number of reactions zones and in each of them such an amount of catalyst and / or such specific volumetric feed rate of the stream (s), defined as the ratio of the feed per unit time and the number of acid groups of the catalyst in the zone that the temperature increase in each reaction zone does not exceed 40 ^o C preferably does not exceed 25 ^o C.

 A variant is proposed according to which the space velocity in each previous reaction zone is 1.3-5 times higher than in the subsequent reaction zone.

 A variant is also proposed according to which a catalyst with a larger particle size and / or lower activity than in subsequent reaction zones is used in the first or each preceding reaction zone.

A variant is proposed according to which the alcohol (s) is supplied completely or predominantly to the first reaction zone, and the hydrocarbon mixture is distributed between the reaction zones, preferably excluding the last reaction zone, in a proportion that ensures that the temperature increase in each zone is limited to no more than 35 ^o C, preferably no more than 20 ^o C.

 An option is proposed according to which adiabatic liquid-phase direct-flow reactors are used in all reaction zones or at least in the last reaction zone and at least in the first reaction zone, reactors are used with heat removal carried out by intermediate cooling and / or recirculation of part of the cooled liquid reaction mixture and / or by evaporation of part of the reaction mixture with its possible condensation and recirculation to the reactor and / or by heat removal through the walls of the apparatus and / or tubes.

 It is also proposed that, when using two hydrocarbon mixtures with different concentrations of tert-alkene (s), at least most of the mixture with a low content of tert-alkene (s) is sent to the first reaction zone.

 A variant is also proposed according to which a thermal or thermocatalytic hydrocarbon conversion fraction containing up to 50% alkadiene (s) is used as the initial tert-alkene-containing mixture, in which α-acetylene hydrocarbons and possibly partially alkadiene (s) are subjected to catalytic hydrogenation, so that the concentration of alkenine (s) in the hydrocarbon mixture fed to the synthesis zone (s) of the alkyl tert-alkyl ether (s) is not more than 0.2%, preferably not more than 0.05%, and is preferably introduced into n its and / or reactor (s) a non-base polymerization inhibitor that neutralizes the acid groups of the catalyst.

 It is also proposed that a tert-alkene-containing mixture with a high concentration of alkadiene (s) is first and / or in the reactor (s) mixed with an inert hydrocarbon (s) and / or another tert-alkene-containing mixture, so that the concentration of alkadiene ( o) in a mixed stream is not more than 25%, preferably not more than 10%.

 A variant is also proposed according to which a tert-alkene-containing mixture is used comprising up to 30% cyclopentadiene and / or its alkyl derivatives, in which cyclopentadiene (s) is subjected to liquid phase thermal dimerization and / or chemical bonding, and a mixture containing not more than 5% is further processed. preferably not more than 1% cyclopentadiene (s).

 In the claims and the description of the invention, the term tertiary alkenes (or tert-alkenes) is understood as isoalkenes in which the double bond is attached to a carbon atom to which an alkyl substituent is attached, for example isobutene, 1-methyl-2-butene, 2-methyl-2- butene and the like

The method allows the processing of various hydrocarbon mixtures containing tert-alkenes, in particular C ₄ fractions and C ₅ fractions of catalytic cracking, gasoline pyrolysis, dehydrogenation of isobutane and isopentane and more complex mixtures, for example C ₄ -C ₅ , C ₄ -C ₆ , C ₄ -C ₇ , C ₅ -C ₆ , C ₅ -C ₇ fractions of catalytic cracking and pyrolysis, C ₄ -C ₅ fractions of co-dehydrogenation of isobutane and isopentane and others.

 Various non-tertiary alcohols can be used: methanol, ethanol, n-propanol, isopropanol, n-butanol and non-tertiary isobutanols, n-pentanol and non-tertiary isopentanols, etc., as well as mixtures of alcohols.

 Various acidic catalysts can be used as catalysts, such as solid, for example, molded (KIF, KU-2FPP, etc.) and fine-grained (Amberlist-15, Amberlist-35, KU-23, Pyrolyte, Phthalosorb, etc.) sulfocationionites in the H-form, and liquid catalysts (phosphoric, sulfuric, boric and other strong acids, mixtures thereof).

 The method allows the use of various types of flow and recirculation reactors, both in a purely adiabatic version (with inter-reactor cooling) and with various types of heat removal. An important advantage of the method is the ability to use the simplest adiabatic and semi-adiabatic reactors, in particular hollow reactors filled with catalyst.

 The use of the method is illustrated in FIG. 1-3 and examples.

 These figures and examples do not exhaust all possible embodiments of the method and other options are possible subject to the essence set forth in the claims.

According to FIG. 1, the stream (s) of the initial hydrocarbon mixture F and alcohol (s) C enter the reactor P-1, after which the reaction mixture is cooled and fed to the reactor P-2. Coming out of P-2, the reaction mixture is cooled and enters the reactor P-3, after which the reaction mixture is possibly cooled and enters the reactor P-4. The resulting reaction mixture M ₃ or / and _k can be directed to the distillation of unreacted hydrocarbons.

 According to FIG. 2, the stream of alcohol (s) "C" enters the reactor P-1, and the initial hydrocarbon mixture F enters in separate streams into the reactors P-1 and P-2 and, possibly, into the reactor P-3.

Between the reactors, the reaction mixture is cooled. The reaction mixture M _k from the final reactor P-3 enters the distillation column K, on top of which a stream "D" is discharged, containing predominantly unreacted hydrocarbons, and a stream of the target product "W" is discharged from the bottom of the column K.

 When relatively light alcohols (methanol, ethanol, etc.) are used as a reagent (s), forming azeotropes with hydrocarbons of the distilled stream or not separated from them by distillation, the distilled stream can be sent to an additional unit “P” for alcohol recovery ( o) by water washing and distilling off the alcohol (s) from water and / or sorption (e.g. zeolites) followed by desorption.

 With the simultaneous use of the second hydrocarbon mixture F 'with a significantly lower concentration of tert-alkenes (than in F), at least a large part of it is fed to the reactor P-1.

According to FIG. 3, a hydrocarbon mixture F, containing (in addition to tert-alkenes (s) and inert hydrocarbons) a significant amount of alkadiene (s) and acetylene compounds, is fed to the catalytic hydrogenation unit "G" or (in the presence of a large amount of cyclopentadiene and / or other cyclodienes) is first fed to the dimerization unit of cyclodiene (s) "D" and then distilled from the resulting dimers (W ') in the apparatus (column) K' and fed to the hydrogenation unit "G" or directly to the ester synthesis reactor (s). The feed of the purified stream F (stream F _o ) is distributed between the reactors P-1 and P-2.

 If at the same time a second hydrocarbon mixture F 'is used, which does not contain a significant amount of alkadiene and acetylene compounds, it is preferably fed to the reactor P-1, or, at a high concentration of tert-alkenes in it, is also distributed between the reactors P-1 and P-2.

Example 1
The process was carried out in accordance with FIG. 1.

As the hydrocarbon feed was used a hydrocarbon mixture of the following composition (wt.%):
isobutane - 52
butene-1 - 4
isobutylene - 44.

 Methanol is used as alcohol.

 In the reactors P-1, P-2, P-3 and P-4, the Amberlist-15 sulfonic ion catalyst was loaded. The characteristics of the catalysts for this and subsequent examples are presented in table. 1.

 The results of the process are presented in table. 2.

 Example 2

 The process is carried out in accordance with FIG. 1 (in three reactors). Hydrocarbon feedstock, as in example 1.

 Ethanol was used as alcohol.

 The reactors P-1, P-2, and P-3 were loaded with KIF-standard, KIF-small, Amberlist-35 catalysts, respectively.

 The results are presented in table. 2.

 Example 3

The process was carried out in accordance with FIG. 1 (in three reactors). Hydrocarbon feedstock, a C ₅ fraction of catalytic cracking, had the following composition (wt.%):
isopentane - 35
pentane - 3
n-pentenes - 30
tert-pentenes (the sum of 2-methylbutene-1 and 2-methylbutene-2) - 27.

 Methanol was used as alcohol.

 The KIF catalyst was loaded into the P-1 reactor, Amberlist-15 into the P-2 reactor, and Amberlist-15 mixture of sulfonic ionite and phosphoric acid on silica gel in a 1: 1 volume ratio was loaded into the P-3 reactor.

 The results are presented in table. 2.

 Example 4

The process was carried out in accordance with FIG. 1 (in three reactors). Hydrocarbon raw materials had the following composition (wt.%):
isobutane - 29
n-butane - 6
butenes - 15
isobutylene - 10
isopentane - 14
pentane - 3
pentenes - 12
tert-pentenes - 11.

 Methanol was used as alcohol.

 In the reactors P-1, P-2 and P-3, a CIF catalyst was charged.

The results are presented in table. 2
Example 5

 The process is carried out in accordance with FIG. 2.

Hydrocarbon raw materials had the following composition (wt.%):
isobutene - 52
butene-1 - 4
isobutylene - 44
Methanol was used as alcohol.

 The KIF catalyst was loaded into reactors P-1 and P-2, and Amberlist -15 was loaded into reactor P-3.

 The results are presented in table. 2.

 Example 6

 An example was carried out in accordance with FIG. 2.

 Hydrocarbon feedstock, as in example 4.

 Methanol was used as alcohol.

 The reactors P-1, P-2, and P-3 were loaded with KIF, KU-23, and Ambelist-15 catalysts, respectively.

 The results are presented in table. 2.

 Example 7

 The process was carried out in accordance with FIG. 3.

 The butane-isobutylene pyrolysis fraction (BIF) (isobutylene content 44 wt.%) Was used as a raw material.

 In the P-1 reactor, the heat of reaction was removed due to the heating of the reaction mass and due to its partial evaporation followed by condensation and return to the reactor.

 Reactors P-2 and P-3 operated in adiabatic mode. The KIF-standard catalyst was loaded into the P-1 and P-2 reactors, a mixture of the Amberlist-15 catalyst and phosphoric acid on silica gel in a 1: 1 volume ratio were loaded into the P-3 reactor.

 The results are presented in table. 3.

 Example 8

 The process was carried out in accordance with FIG. 3.

 Hydrocarbon feedstock, as in example 7.

 In the P-1 reactor, the heat of reaction was removed by heating the reaction mass and by recirculating the reaction mass and exiting the reactor to the inlet with cooling it from the outlet temperature to the inlet temperature.

 The KIF-standard catalyst was loaded into the P-1 and P-2 reactors, and the “small” KIF reactor was loaded.

 The results are presented in table. 3.

 Example 9

 The process was carried out in accordance with FIG. 3.

 Hydrocarbon feedstock, as in example 7.

 The P-1 reactor is tubular, the heat of reaction was removed by the refrigerant circulating in the annulus.

 The KIF catalyst “small” was loaded into the P-1 reactor, Amberlist-15 sulfocationionite (fraction (0.8-1.2 mm), into the P-2 reactor, Amberlist-15 (fraction (0, 2-0.6 mm).

 The results are presented in table. 3.

 Example 10

 The process was carried out in accordance with FIG. 3.

Two fractions of C ₄ hydrocarbons were used as raw materials: butane-isobutylene fraction (BIF) of pyrolysis (isobutylene content 44 wt.%) And butane-butylene fraction (BBP) of catcracking (12% isobutylene content).

 In the P-1 reactor, the heat of reaction was removed mainly due to the evaporation of part of the reaction mass with its subsequent condensation and return to the reactor inlet.

 The KU-2FPP catalyst was loaded into the P-1 reactor. In the P-2 reactor, the CIF is “shallow”, in the P-3 reactor - KU-23 cation exchange resin.

 As the alcohol used n-propanol.

 The results are presented in table. 3.

 Example 11

 The process was carried out in accordance with FIG. 3.

As fractions, 2 fractions were used: butane-divinyl fraction (BDF) with the composition (wt.%):
isobutane - 3.2
n-butane - 8.5
isobutylene - 24.0
n-butenes - 24.75
1,3-butadiene - 39.1
the amount of acetylene - 0.45
and BBP catcracking, having the composition as in example 10.

BDP pyrolysis was previously purified from acetylene hydrocarbons by catalytic hydrogenation at a temperature of 20 ^o C.

 The catalyst used was the K-PG catalyst (palladium on alumina). The amount of acetylene hydrocarbons after hydrogenation was 0.02%.

 In the reactors for the synthesis of alkyl tert-alkyl esters, methanol was used as the alcohol. All methanol was fed to the P-1 reactor.

 70% of the BBP catcracking was fed to the P-1 reactor along with the entire amount of the BDP pyrolysis. 30% BBP catcracking was fed to the P-2 reactor. The ratio of the amount of BDP pyrolysis to the amount of BBP catcracking at the inlet to the P-1 reactor was 1: 3, the concentration of 1,3-butadiene at the inlet to P-1 was 9.8 wt. %

 The reactor P-1 is tubular, as in example 9.

 Catalyst loading as in example 9.

 The results are presented in table. 3.

 Example 12

 The process was carried out in accordance with FIG. 3.

The raw material used was a C ₅ pyrolysis fraction with the composition (wt.%):
isopentane - 11.0
n-pentane - 17.2
pentenes - 6.5
isoamylenes (the sum of 2-methylbutene-1 and 2-methylbutene-2) - 9.5
isoprene - 15.0
piperylene - 10.5
cyclopentadiene (CPP) - 30.0
the amount of acetylene - 0.3
The C ₅ fraction was preliminarily subjected to catalytic hydrogenation of acetylene hydrocarbons on a K-PG catalyst at a temperature of 20 ^° C. The content of the sum of acetylene hydrocarbons after hydrogenation was 0.01 wt.%.

 Methanol was used as the alcohol in the reactor for the synthesis of alkyl tert-alkyl esters.

 The reactor P-1 is tubular, as in example 9.

 Catalyst loading as in example 9.

 The results are presented in table. 3.

 Example 13

 The process was carried out in accordance with FIG. 3.

As fractions, 2 fractions were used: C ₅ -fraction of pyrolysis, as in example 12 and C ₅ -fraction of catalytic cracking, as in example 2.

The C ₅ pyrolysis fraction was preliminarily purified from cyclopentadiene by liquid phase thermal dimerization of the CPD at a temperature of 100 ^° (block D, Fig. 3) and, after separation of the formed dicyclopentadiene in column K '(Fig. 3), it was sent to purification from acetylene hydrocarbons by catalytic hydrogenation (block 5, Fig. 3).

 The residual content of the sum of acetylene hydrocarbons was 0.01 wt.%.

After the hydrogenation unit, the C ₅ fraction had the following composition (wt.%):
isopentane - 15.6
n-pentane - 24.0
pentenes - 10.2
isoamylene - 13.5
isoprene - 20.6
piperylene - 14.4
cyclopentadiene - 2.8.

At the inlet of the P-1 reactor, the C ₅ pyrolysis fraction was mixed with the C ₅ fraction of catcracking in a 1: 1 ratio. The content of diene hydrocarbons in the hydrocarbon feed was (wt.%):
isoprene - 10.3
piperylene - 7.2
CPD - 1.4.

 Methanol was used as alcohol. The reactor P-1 is tubular, as in example 9. The loading of the catalyst as in example 9. The results are presented in table. 3.

Claims (9)

1. A method of producing alkyl tert-alkyl esters or mixtures thereof with hydrocarbons and / or alcohols by contacting mixtures of hydrocarbons containing at least tertiary alkenes and non-tertiary alcohol (s) in the presence of acid catalysts in two or more reaction zones completely or predominantly in a liquid state with intermediate cooling of the streams and possible subsequent distillation of unreacted hydrocarbons and recovery of alcohol (s) on them, characterized in that such a number of reaction zones are used in each of these, such an amount of catalyst and / or such specific volumetric feed rate of the stream (s), defined as the ratio of the feed per unit time to the number of acid groups of the catalyst in the zone, that the temperature increase in each reaction zone does not exceed 40 ^o C, preferably does not exceed 25 ^o C.  2. The method according to claim 1, characterized in that in each previous reaction zone, the space velocity is maintained 1.3 to 5 times higher than in the subsequent reaction zone.  3. The method according to claims 1 and 2, characterized in that in the first or each preceding reaction zone, a catalyst with a larger particle size and / or lower activity is used than in subsequent reaction zones. 4. The method according to claims 1 to 3, characterized in that the alcohol (s) is supplied completely or mainly to the first reaction zone, and the flow of the hydrocarbon mixture is distributed between the reaction zones, preferably excluding the last reaction zone, in a proportion that limits the temperature increase in each zone is not more than 35 ^o C, preferably not more than 20 ^o C.  5. The method according to claims 1 to 4, characterized in that the use of adiabatic liquid-phase direct-flow reactors in all reaction zones or at least in the last reaction zone and at least in the first reaction zone use reactors with heat removal carried out by intermediate cooling, and / or recirculation of part of the cooled liquid reaction mixture, and / or by evaporation of part of the reaction mixture with its possible condensation and recirculation to the reactor, and / or by heat removal through the walls of the apparatus and / or tubes.  6. The method according to claims 1 to 5, characterized in that when using two hydrocarbon mixtures with different concentrations of tert-alkene (s) at least most of the mixture with a low content of tert-alkene (s) is sent to the first reaction zone.  7. The method according to claims 1 to 6, characterized in that, as the initial tert-alkene-containing mixture, a fraction of the thermal or thermocatalytic conversion of hydrocarbons containing up to 50% alkadiene (s) is used, in which α-acetylene hydrocarbons are previously subjected to catalytic hydrogenation and possibly partially alkadiene (s) so that the concentration of alkenine (s) in the hydrocarbon mixture fed to the synthesis zone (s) of the alkyl tert-alkyl ether (s) is not more than 0.2%, preferably not more than 0, 05%, and is preferably introduced into it and / or eaktor (s) polymerization inhibitor is not a base, neutralizing the acid groups of the catalyst.  8. The method according to claims 1 to 7, characterized in that the tert-alkene-containing mixture with a high concentration of alkadiene (s) is first and / or in the reactor (s) mixed with an inert hydrocarbon (s) and / or tert-alkene-containing mixture, so that the concentration of alkadiene (s) in the mixed stream is not more than 25%, preferably not more than 10%.  9. The method according to claims 1 to 8, characterized in that a tert-alkene-containing mixture is used comprising up to 30% cyclapentadiene and / or its alkyl derivatives, in which cyclopentadiene (s) is subjected to liquid-phase thermal dimerization and / or chemical bonding, and further processing subjecting a mixture containing not more than 5%, preferably not more than 1%, cyclopentadiene (s).

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