JPH04338349A - Method of preparing ether - Google Patents

Abstract

PURPOSE: To produce a high purity asymmetric tertiary alkyl ethers each of which is useful as an additive for enhancing the octane number of gasoline contg. 5-10C hydrocarbons, such as methyl tertiary butyl ether, tertiary amyl methyl ether, or the like, in a high yield by using a multistage process and reducing the deterioration of a catalyst employed for the process.

CONSTITUTION: This production comprises: allowing a C₄ + hydrocarbon raw material 1 containing isoalkenes, together with an aliphatic alcohol 3 to contact with portions 2 and 4 of an inorganic metal oxide catalyst under conditions sufficient to perform partial etherification of the isoalkenes; and thereafter, allowing a mixture 7 of the resulting ethers, unreacted alcohol and unreacted alkenes to contact with a resinous catalyst in a distillation column 6 that contains the resinous catalyst preferably in plural fixed bed contact-distillation regions, under conditions sufficient to substantially complete etherification of the isoalkenes, to recover a C₅ + tertiary alkyl ether product 11 and to produce the objective high purity asymmetric tertiary alkyl ethers in high yields. At this time, in order to remove coke and impurities from the metal oxide catalyst and to restore the catalyst activity, periodical regeneration of the metal oxide catalyst is desired.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multistage process and apparatus for producing asymmetric tertiary ethers in high yield and purity.

0002

BACKGROUND OF THE INVENTION It would be desirable to improve the octane performance of gasoline without adding harmful components such as tetraethyl lead and benzene. Low molecular weight non-target ethers such as MTBE to increase octane number.
It has been found that TAME (methyl tertiary butyl ether) and TAME (tertiary amyl methyl ether) can be added to C5-C10 hydrocarbon containing gasoline products. MTB
The E's research octane number (RON) is indicated as 115-135, and its motor octane number (MON) is 98-11.
0, and its blend octane number [(RON+M
ON)/2] is 106 to 122.5. Blend octane number increases as the MTBE concentration decreases and as the base fuel saturates concentration increases.

Conventional etherification processes use macroreticular cation exchange resins, such as hydrogen-type Amberlyst 1, as catalysts.
5 is used. Resin catalysts give high conversion rates, but
Not suitable for high temperatures (approximately 90°C or higher). When overheated, the resin catalyst releases sulfonic acid and sulfuric acid. In addition, upon washing out the acid material from the resin catalyst, even at normal operating temperatures, a reverse reaction, ie, decomposition of the ether product into starting materials, occurs during distillation of the ether product. This significantly reduces the overall yield. Additionally, resin catalysts are susceptible to poisoning by substances such as sulfur, organic nitrogen, metals, and water. Resin catalysts are susceptible to activity loss during regeneration.

Conventional etherification processes are typically carried out in the liquid phase at temperatures below 90° C. and pressures of about 14.6 bar (200 psig). Equilibrium is favored at low temperatures, but
The reaction rate becomes significantly slower. It is also believed that an excess of methanol is required to achieve acceptable selectivity.

It is known to use acidic intermediate pore zeolite catalysts to convert isoolefins and alcohol starting materials to ethers with high selectivity. Examples of such zeolites are ZSM-4, ZSM-5, ZSM
-11, ZSM-12, ZSM-23, ZSM-35,
ZSM-50 and Zeolite Beta. Due to their lower acidity compared to resin catalysts, higher reaction temperatures are required for zeolites to achieve the desired conversion rates. Zeolite catalysts are much more thermally stable than resin catalysts, are not affected by methanol to isobutene ratio, do not produce acidic effluents, and can be easily and quickly regenerated.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, C
A method for producing a non-target tertiary alkyl ether from a 4+ hydrocarbon raw material is to contact the raw material with an aliphatic alcohol and an inorganic metal oxide catalyst under conditions for partial etherification of an isoalkene, and the resulting ether, contacting the mixture of unreacted alcohol and unreacted alkene with an acidic resin catalyst under conditions to substantially complete etherification of the isoalkene and recovering a C5+ tertiary alkyl ether product.

Preferably, the metal oxide catalyst is periodically regenerated to remove coke and feed impurities and to restore catalyst activity. The mixture is subjected to multiple fixed bed contact-
More preferably, the contact with the resin catalyst is carried out in a distillation column containing the resin catalyst in the distillation zone.

The feedstock and alcohol can be contacted with the metal oxide catalyst in one of a plurality of fixed bed reactors operably connected to switch between production and regeneration. Alternatively, the feedstock and alcohol can be contacted with a fluidized bed of metal oxide catalyst from which a portion of the catalyst can be removed, regenerated, and returned to the bed. The feedstock and alcohol may be contacted with the catalyst in a slurry type reactor. Whichever type of reactor is used, the feedstock and alcohol are subjected to metal oxidation in at least two consecutive reaction zones, each successive zone being maintained at a temperature at least 5° C. lower than the temperature of the previous zone. may be contacted with a catalyst.

When a resin catalyst is used in a distillation column, the reaction is carried out at a temperature of 10-30°C above the temperature at which the partial etherification takes place.
It is carried out at a lower temperature. Advantageously, the recovered ether product is further purified by fractional distillation. Regeneration of the metal oxide catalyst can be carried out by stripping with a stream of hydrogen at 371-538°C.

Preferably, the metal oxide catalyst comprises an intermediate pore zeolite, in particular a zeolite with the structure ZSM-5, ZSM-11, ZSM-50 or zeolite beta. The resin catalyst preferably comprises a polymeric sulfonic acid resin, such as a macroreticular polystyrene sulfonic acid resin. An important feature of the invention is that during the partial etherification step, butadiene, isoprene,
cyclopentadiene, and/or N, Al,
The purpose is to remove impurities containing Fe, Na and/or Mg.

In a preferred embodiment, the raw material is primarily C4
+ hydrocarbons, including isobutene, which accounts for at least 10% by weight of the feedstock. However, the isoalkene component of the feedstock may also be a higher alkene, such as isoamylene. Typically the aliphatic alcohol is methanol, ethanol or isopropanol and the partial ethanolization conditions involve operation in the liquid phase.

[0012] In one aspect of the present invention, a multi-stage process for etherifying mixed C4+ olefinic hydrocarbon feedstocks containing isoalkenes is provided. The multi-stage process involves contacting the olefinic feedstock and the aliphatic alcohol with a renewable metal oxide acidic solid catalyst under partial etherification conditions in a first reaction step to convert the majority of the isoalkenes to C5+ tertiary alkyl ethers. Including converting. The reaction effluent is
A reaction effluent is recovered from the first stage and contains ether product, unreacted alkyl and isoalkene containing unreacted olefins. The reaction effluent from the first stage is fed in a second stage to a catalytic distillation column containing a solid acidic resin etherification catalyst in multiple fixed bed catalytic distillation zones. In the second stage, the etherification of the isoalkene is substantially complete. A liquid product containing C5+ ether is recovered from the catalytic distillation column.

The first stage solid catalyst can be regenerated to remove feed impurities and coke and restore acid activity. The reactivated catalyst is returned to the first stage for further ether production. Regeneration of metal oxide catalysts such as ZSM-5 is much more cost effective than purification of contaminated acidic resin catalysts.

FIG. 1 is a flow diagram of a preferred embodiment of the invention, showing the main equipment and the flow of reactants and products.

In a preferred embodiment, the present invention provides MTBE
Provides a manufacturing method. This process increases selectivity and yield and significantly reduces resin catalyst destruction. Two reaction zones are arranged in series. The first reaction zone includes solid crystalline mesoporous metallosilicate catalyst particles. The second reaction zone contains an acidic resin catalyst. A mixed feed comprising methanol and isobutene-containing C4+ hydrocarbons is contacted with solid catalyst particles under etherification conditions in a first reaction zone to obtain an intermediate product comprising MTBE and unreacted feed. The intermediate product is removed from the first reaction zone and sent to the second reaction zone where it is contacted with an acidic resin catalyst under etherification conditions. A product containing a major amount of MTBE is removed from the second reaction zone. The product is fractionated to obtain purified MTBE, which is recovered.

The preferred method of the invention further comprises removing the first reaction zone from on-line contact with the feedstock, regenerating the solid catalyst particles in the first reaction zone, and re-adding the feedstock to the first reaction zone. Including. Preferred solid acidic catalyst particles are aluminosilicate zeolites selected from ZSM-5, ZSM-11, ZSM-50 or zeolite beta. Since mixed olefinic feedstocks contain many impurities, even after treatment and water washing in a "Merox" unit, the solid acidic zeolite catalysts are highly contaminated after on-line contact with the feedstocks. Impurities adsorbed on the zeolite particles include nitrogen compounds, metals (eg, Al, Fe, Na, and Mg), oligomers of olefins (eg, isoprene and cyclopendadiene), diolefins, and the like. Diolefin compounds and other related hydrocarbons are deposited as coke on the surfaces or interstices of the catalyst particles. Therefore,
An important advantage of the present invention is that in the first reaction zone, feed impurities are removed in parallel with ether production, and the mixed oxide catalyst acts as a guard bed to prevent contamination of the downstream resin catalyst. It is.

The first reaction zone preferably includes a plurality of fixed bed reactors operably connected to be alternately switched between production mode and regeneration mode. Therefore,
Continuous operation is maintained even when the fixed bed must be removed from production for catalyst regeneration. In one embodiment of the process of the invention, the first reaction zone includes at least three catalytic fixed bed reactors, two of which are in operation at all times. Thus, the isoolefin-containing feedstock and alcohol are continuously contacted with the acidic intermediate pore zeolite catalyst in the first reaction zone.

In another embodiment, the first reaction zone may include a reactor such as a moving bed, slurry, fluidized bed or ebullated bed rather than a fixed bed. The number and type of reactors containing the acidic zeolite catalyst can be adjusted to optimize product yield and overall energy consumption.

Catalyst regeneration comprises removing the contaminated zeolite catalyst particles in a regeneration zone under conditions of temperature and pressure sufficient to remove at least a major amount of impurities from the catalyst particles.
This can be carried out by contacting with oxygen or an oxygen-containing gas. Typical oxidative regeneration conditions are 371-510
°C (700-950 °F) and 1-14.6 bar (
0-200 psig). In another aspect, 371-
The zeolite catalyst particles can be regenerated by stripping with a hot stream of hydrogen at 538°C (700-1000°F). Hydrogen stripping avoids the problem of catalyst deactivation due to "steaming" that occurs under oxidative regeneration conditions due to water formation.

Since the zeolite catalyst particles are easily regenerated, the mixed olefinic feedstock may contain significant amounts of impurities. If desired, the step of washing the raw materials with water can be omitted. Therefore, isobutene-containing feedstocks of low quality can also be used in resin-catalyzed etherification reactions.

[0021] The second reaction zone contains an acidic resin catalyst;
Preferably the resin catalyst is a macroreticular polystyrene sulfonic acid resin catalyst. In a preferred embodiment, the second reaction zone comprises a plurality of fixed bed contacts located in the upper half of the distillation column.
The distillation apparatus has a catalytic distillation column containing a polystyrene sulfonic acid resin catalyst. The reaction zone column is preferably operated at a temperature about 10-30° C. lower than the temperature of the first reaction zone.

In other embodiments, the second reaction zone may be a reactor or reactors rather than a catalytic distillation column. The reactor may be of any shape, such as fixed bed, stirred slurry (U.S. Pat. No. 3,940,450), etc.
(see issue), swing or boiling beds. Any desired reactor geometry acceptable to those skilled in the art can be employed. For example, acidic resin catalysts can be used in accordance with renewable etherification catalysts. In a preferred embodiment, the resin catalyst is Amberlyst 15.

[0023] Viewed from one aspect, the present invention has the following advantages over the conventional method:
With the addition of a preliminary step of contacting the olefin and alcohol reactants in the liquid phase under partial etherification conditions with oxidatively regenerable solid acidic catalyst particles, intermediate products containing tertiary alkyl ethers and unreacted olefins and alcohols are produced. It can be seen as obtaining. This intermediate product is substantially free of impurities that reduce catalyst activity;
Sent to routine processing.

The preferred alcohol is methanol, but ethanol or isopropanol can also be used to obtain different ether products. The use of mixtures of low molecular weight alcohols is also encompassed by the invention. Although isobutene is the preferred hydrocarbon feedstock, other isoolefins such as 3-methyl-2-butene can also be etherified by the process of the invention.

The novel apparatus for carrying out the present invention comprises an inlet means for receiving a mixed feed containing an olefin and an alcohol, a reactor system containing solid acidic intermediate pore zeolite catalyst particles, and an ether and an unreacted zeolite catalyst. a first comprising outlet means for removing intermediate product including raw materials;
It has a reaction area. The apparatus further includes an inlet means for receiving the withdrawn intermediate product, a catalytic distillation column containing a solid acidic resin etherification catalyst in a plurality of fixed bed catalytic-distillation zones;
and a second reaction zone comprising outlet means for removing the etherified final product. The apparatus also includes means for transporting the intermediate product from the first reaction zone to the second reaction zone.

Referring to the drawings, a precleaned C4+ hydrocarbon feed from line 1, which may contain impurities, is combined with a low molecular weight alcohol feed from line 3. The combined flow passes through line 12 to reaction zone 2.
to go into. A renewable solid metal oxide acidic catalyst, such as ZSM-5, is included in reaction zone 2. The mixed alcohol/C4+ hydrocarbon feed is contacted with a solid catalyst in reaction zone 2 at predetermined temperature and pressure reaction conditions and is at least partially converted to MTBE. Impurities contained in the feedstock are effectively removed from the partially converted feedstock by the solid acid catalyst.

The first intermediate product containing MTBE, unreacted C4+ hydrocarbons and alcohol is cooled before entering reaction zone 4 from line 5. Reaction zone 4 contains a renewable solid metal oxide acidic catalyst, such as ZSM-5. The first intermediate product is contacted with a solid catalyst under etherification conditions to obtain MTBE. Any impurities contained in the first intermediate product are adsorbed onto the solid catalyst.

Regeneration of the solid acidic catalyst in both reaction zones 2 and 4 is accomplished by methods well known in the art. A series of swing reactors can be used, with reactors containing contaminated and deactivated catalyst removed from the process and immediately switched to reactors containing active catalyst. Reaction zones 2 and 4 may be catalytic fixed bed reactors arranged in series or may be combined into a single moving bed, slurry or ebullated bed reaction zone. catalytic material,
Preferably, ZSM-5 can be regenerated by contacting with oxygen or an oxygen-containing gas at elevated temperatures.

A second intermediate product comprising MTBE and unreacted C4+ hydrocarbons and alcohol is removed from reaction zone 4 and sent via line 7 to catalytic distillation column 6. In a preferred embodiment, the temperature of the second intermediate product is
It is lowered before entering the distillation column. In distillation column 6,
A substantial portion of unreacted C4+ hydrocarbons and alcohols are converted to MTBE by a polystyrene sulfonic acid resin catalyst, such as Amberlyst 15. Etherification over a resin catalyst is preferably carried out at a temperature of about 37-75°C and about 10-350 psig
) pressure is applied. In a preferred embodiment, the acidic resin catalyst is placed in the rectification section of the debutanizer column used to stabilize the ether. Products containing MTBE are
It can be taken off from the distillation column 6 via line 11.

Poisoning of the polysulfonic acid resin catalyst, which is common when used for etherification, will be explained. MTB
It is assumed that the E-resin catalyst device is operated continuously for 6 months. The hydrocarbon feed containing isobutene is treated in a Merox unit and washed with water before being sent to the MTBE reactor. 6
The conversion rate drops from 93% to 52% over the course of a few months. Analysis shows contaminants on the resin catalyst. The main contaminants are nitrogen compounds, which account for about 60% of catalyst deactivation. The nitrogen concentration on the deactivated resin catalyst is
It is approximately 25×10 3 ppm. Metals such as Al, Fe, Na and Mg also account for about 10% of the passivation. Such metal sources are primarily water wash towers. The metal concentration on the deactivated catalyst is approximately 15 x 102 ppm.

A third type of impurity is coke. Coke is formed on the resin catalyst due to the presence of components such as cyclopendadiene and isoprene in the hydrocarbon feedstock. In particular, controlling the diolefinic C5 hydrocarbon content requires continuous monitoring of the feedstock. One of the advantages of the process of the invention is that the coke formation occurs primarily over the zeolite catalyst. Therefore, oxidative regeneration or hydrogen stripping of the zeolite catalyst can effectively remove coke and non-metallic contaminants from the etherification catalyst.

The main contaminants in the water washed hydrocarbon feedstock were found to be acetone and nitriles. For example, the raw material sample contains 190 ppm acetone, 3p
pm of acetonitrile and 16 ppm of propionitrile. An advantage of the present invention is that there is no need to wash the hydrocarbon feedstock.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of the etherification method of the present invention.

[Explanation of symbols]

Claims (20)

[Claims] 1. A method for producing a non-target tertiary alkyl ether from a C4+ hydrocarbon raw material containing an isoalkene, the raw material being combined with an aliphatic alcohol to form an inorganic metal oxide under conditions for partial etherification of the isoalkene. The resulting mixture of ether, unreacted alcohol, and unreacted alkene is contacted with an acidic resin catalyst under conditions to substantially complete etherification of the isoalkene to form a C5+ tertiary alkyl ether product. A manufacturing method comprising recovering. [Claim 2] Remove coke and raw material impurities,
2. The method according to claim 1, wherein the metal oxide catalyst is periodically regenerated to restore catalytic activity. 3. A process according to claim 1, wherein the mixture is contacted with a resin catalyst in a distillation column containing the resin catalyst in a plurality of fixed bed contact-distillation zones. 4. The feedstock and alcohol are contacted with the metal oxide catalyst in one of a plurality of fixed bed reactors operably connected to switch between production and regeneration. The manufacturing method described in any of the above. 5. A process according to claim 1, wherein the raw material and the alcohol are brought into contact with a fluidized bed of metal oxide catalyst, from which the catalyst is removed, regenerated and returned to the bed. 6. The method according to claim 1, wherein the raw material and alcohol are brought into contact with a catalyst in a slurry reactor. 7. The feedstock and alcohol are contacted with the metal oxide catalyst in at least two consecutive reaction zones, each successive zone being maintained at a temperature at least 5° C. lower than the temperature of the previous zone. 7. The manufacturing method according to any one of 1 to 6. 8. The process according to claim 3, wherein the reaction is carried out in a distillation column at a temperature 10 to 30° C. lower than the temperature at which the partial etherification is carried out. 9. A process according to claim 1, wherein the recovered ether product is further purified by fractional distillation. 10. The metal oxide catalyst, 371 to 538
10. Process according to any of claims 2 to 9, characterized in that it is regenerated by stripping with a stream of hydrogen at <0>C. 11. The method according to claim 1, wherein the metal oxide catalyst comprises an intermediate pore zeolite. [Claim 12] The zeolite is ZSM-5, ZSM
-11, ZSM-50 or zeolite beta structure. 13. The method according to claim 1, wherein the resin is a polymeric sulfonic acid resin. 14. The method according to claim 13, wherein the resin is a giant reticular polystyrene sulfonic acid resin. 15. During the partial etherification step, impurities comprising butadiene, isoprene, cyclopentadiene and/or N, Al, Fe, Na and/or Mg are removed from the reactants. 14. The manufacturing method according to any one of 14. 16. The process according to claim 1, wherein the raw material consists primarily of C4+ hydrocarbons and contains isobutene. 17. The method of claim 16, wherein isobutene accounts for at least 10% by weight of the feedstock. 18. The method according to claim 1, wherein the raw material contains isoamylene. 19. The aliphatic alcohol is methanol,
Claims 1 to 1 which are ethanol or isopropanol.
8. The manufacturing method according to any one of 8. 20. The method according to claim 1, wherein the partial ethanolization conditions include operation in a liquid phase.