JPH0753723B2 - Method for producing gamma-butyrolactone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of producing gamma-butyrolactone,
Dialkyl esters of C ₄ dicarboxylic acids, especially maleic acid, fumaric acid, or succinic acid, usually di- (C _1-
C ₄ alkyl) Gamma by hydrogenolysis of ester - about how the generation of butyrolactone.

Gamma-butyrolactone is used as a solvent for various reactions, as a solvent for high polymers, and as a chemical synthetic intermediate for nylon polymers.

It is often produced from butane-1,4-diol,
It itself is produced by acetylene and formaldehyde which react by the Reppe reaction, but-2-yn-1,
The 4-diol is formed and further hydrogenated to give butane-1,4-
Form a diol.

Alternatively, European Patent Application 0018162 proposes reacting allyl alcohol produced from propylene with iso-butylene to form allyl t -butyl ether. This compound is then hydroformylated, for example with a catalyst for radium complex hydroformylation, to give 4- t -butoxybutyraldehyde, which is further oxidized and decomposed with the aid of an acidic catalyst, accompanied by dehydration and deoxidization. Yields gamma-butyrolactone.

There are several further proposals for the production of butane-1,4-diol from maleic anhydride. According to these proposals, maleic anhydride, which is produced by the oxidation of butane or benzene, is esterified to give the diester of maleic acid and then hydrogenated in one or more stages to give butane. This produces a 1,4-diol. Alternatively, it has been proposed that maleic acid or maleic anhydride must be hydrogenated directly. In some of these proposals, butyrolactone is an intermediate.

U.S. Pat. No. 4,001,282 discloses a process for the production of butyrolactone by passing vaporized maleic acid, maleic anhydride, or a mixture thereof with water and hydrogen, through a metal catalyst capable of hydrolyzing a carboxyl group to a hydroxylmethyl group. Will be explained. A typical catalyst is a copper-zinc catalyst (Gird
ler G-66-ARS and G-66-BRS) and copper chromite catalyst (such as Girdler G-13). Other products reported besides butyrolactone include succinic anhydride, propionic acid, butyric acid, propanol and n -butanol.

US Pat. No. 4,048,196 describes the production of butane-1,4-diol and / or tetrahydrofuran by hydrogenation of a multi-step catalyzed reaction of maleic anhydride or succinic anhydride. In the first liquid phase hydrogenation stage, maleic anhydride or succinic anhydride is hydrogenated with a nickel catalyst to give butyrolactone. This is copper oxide /
Hydrogenated with zinc or hydroxide catalyst, butane-1,4
Yields a diol and tetrahydrofuran.

US Patent 4083809, US Patent 4105674, and UK Patent Application 1
In 534136, a method of producing butyrolactone with Cu-Pd catalysts for the gas phase hydrogenation of maleic acid, succinic acid, their anhydrides, and mixtures of two or more thereof is described.

US Pat. No. 20,794,14 describes the use of copper chromite as a catalyst to achieve the hydrogenation of esters. In gas phase operation, it is recommended that temperatures within the range of 300 ° C to 400 ° C should be used.
Also mentioned is diethyl succinate.

US Patent No. 2040944 recommends the use of temperatures from 230 ° C to 400 ° C for the hydrogenation of esters of non-aromatic polybasic acids with aliphatic monohydric alcohols containing at least 4 carbon atoms. . Copper chromite is recommended as the catalyst, which is prepared by the intense heat of the ammonium ammonium chromate precipitate and used without further treatment, or
Explain that it is used after reduction with hydrogen at a temperature of 500 ° C. or higher. It goes on to state that either the liquid phase or the gas phase is used and relies heavily on the ester to be hydrogenated. Barometric pressure of 100 to 250 bar,
In addition, it is recommended to use about 5 to 20 mol of hydrogen per mol of ester. Example 1 illustrates a liquid phase batch reaction in which unpurified butyl succinate is hydrogenated at 3000 psi (207 bar) at 255 ° C. using a copper chromite catalyst.

The discussion of using copper chromite as a catalyst for the hydrogenation of esters was made in 1954 by J. Wiley and Sons, Inc.
Published by "Organic Reaction"
s) ”, Volume 8, Part 1 of this reference.
Chapter is Homer Adkins, “Catalytic Hydrogenation of E
ster to Alcohols) ”. Table II on page 15 lists two experiments in which diethyl succinate was 5000 ps.
i (345 bar), 150 ° C. for 4 hours, and 3300 psi (227.5 bar), 250 ° C. for 6 hours and a half, respectively. This quote says that the "copper chromite" catalyst is an oxidizing second
This suggests that it is more accurately explained as a substantially equimolecular combination of copper and cuprous chromate, that is, CuO and CuCr ₂ O ₄ .

The production of copper chromite catalysts for use in the hydrogenation of esters is described in French patent application 1276722. Here, between 100 ° C and 350 ° C, preferably 200 ° C and 300 ° C
The use of conditions for ester hydrogenation is recommended, including the use of temperatures between 0 ° C and preferably hydrogen pressures between "50hpz and 500hpz" (probably between 50 and 500 bar). There is.

According to the method in which the dialkyl maleate is hydrolyzed in the liquid phase in the presence of a catalyst for copper chromite,
The production of butane-1,4-diol and tetrahydrofuran is described in British patent application 1454440 and British patent application 1464263. A similar liquid phase process using nickel-based catalysts is described in British Patent Application 1587198.

Hydrogenation of di- (C ₁ -C ₇ alkyl) succinate to produce butane-1,4-diol is catalyzed by copper chromite at atmospheric pressures of 100 to 300 and 200 ° C. to 260 ° C. , German Patent Application 2719867.

U.S. Pat. No. 4,172,961 is Example 1 in which a mixture of dibutyl butoxysuccinate, dibutyl maleate and dibutyl fumarate is used at 2000 psi to 4000 psi with a copper chromite catalyst.
Hydrogenated at a temperature of 250 ° C. (141.65 bar to 282.26 bar) to produce butane-1,4-diol,
I will explain the experiment.

The dialkyl maleate was first added in the first hydrogenation zone,
A two-stage hydrogenation process is described in which the corresponding dialkyl succinate is hydrogenated and then the resulting dialkyl succinate is hydrogenated to produce butane-1,4-diol in the second hydrogenation zone. Described in US Pat. No. 4032458. Copper chromite has been suggested as a catalyst for use in both hydrogenation zones. In the first hydrogenation region, the temperature is about 100 ℃ to about 200 ℃, and about 2000ps
i to about 3500 psi (about 141.65 bar to about 247.11 bar)
It is recommended to use a hydrogen pressure of about 225 ° C to about 300 ° C and about 3000 psi to about 4 in the second hydrogenation zone.
The use of atmospheric pressures of 000 psi (about 241.95 bar to 282.26 bar) is described and the operating conditions necessary to convert nearly all the dialkyl ester to a product consisting of butane-1,4-diol and a monovalent alkanol. There is strict strictness.

According to British Patent Application 1168220, butyrolactone is a copper compound obtained by adding maleic anhydride, succinic acid, an ester of maleic acid, an ester of succinic acid, or an ester of fumaric acid to a small amount of one or more promoters other than chromium. -Produced by gas phase hydrogenation in the presence of a zinc catalyst. This specification states that the preparation of butyrolactone by hydrogenation of a selected starting material is already known, and "when the selected catalyst is copper chromite, hydrogenation is preferred. It is also possible to carry out in phases "(see page 1, lines 23-25). British patent application 1168220 states, “In addition, the gas phase hydrogenation processes known to date suffer from the disadvantage that they have to be carried out at relatively high temperatures, for example around 300 ° C. In order to obtain the reaction, the reactants must be fed to the catalyst at a slow rate, and it is more difficult to reactivate the copper chlorite catalyst when its activity is reduced by use for a certain period of time. . "(See page 1, lines 29-39).

The object of the present invention is to provide a new and improved process for the production of gamma-butyrolactone, which, as starting material,
It uses a precursor produced from maleic anhydride, ie, butane or benzene as the final feedstock.

The method for producing gamma-butyrolactone according to the present invention comprises providing first and second hydrogenolysis zones, each area containing a packing of a heterogeneous ester hydrogenolysis catalyst, and a first hydrogenolysis zone. To elevated first pressure above the threshold temperature for the hydrogenolysis reaction at elevated pressure
At the material temperature, and more dialkyl ester and hydrogen excess gaseous C ₄ dicarboxylic acid, supplying a first vaporous feed stream, the ester, first hydrogenolysis region, hydrogen substantially adiabatic reaction conditions In addition to unreacted hydrogen, which is substantially freed from the initiating ester by addition decomposition, a first molar ratio of gamma-butyrolactone and butane-1,4-
Forming a vaporous first reaction mixture comprising a diol, heating the vaporous first reaction mixture, and producing a second vaporous feed stream comprising the heated vaporous first reaction mixture. Supplying a second feedstock temperature to the second hydrocracking zone at a second feedstock temperature above a threshold temperature for the hydrocracking reaction, and a second vaporous feedstock stream in the second hydrocracking zone in a substantially adiabatic reaction. Further reacting and equilibrating under the conditions, from the second hydrogenolysis region, in addition to unreacted hydrogen, a second molar ratio of gamma-butyrolactone and butane-1,4 higher than the first molar ratio. -A diol and a second reaction mixture in vapor form containing the diol.

Preferably the hydrocracking catalyst comprises copper chromite. In particular, prior to reduction, it is preferred to use reduced copper chromite containing about 25 to about 45% by weight copper and about 20 to about 35% by weight chromium.

If possible, the ester is preferably a di- (C ₁ -C ₄ alkyl) ester of bute-2-yne-1,4-diol acid or succinic acid.

For copper chromite catalyzed operation according to the method of the present invention, it is preferred to operate at a temperature of at least about 170 ° C. Therefore, the temperature of the first raw material is preferably about 170 ° C to about 260 ° C.
C., preferably about 190.degree. C. to about 230.degree. C .. The two hydrocracking zones are each operated substantially adiabatically. The first reaction mixture thus exits the first hydrocracking zone at a temperature above the first injection temperature. The second injection temperature when the cooled first reaction mixture in the vapor state is supplied to the second hydrogenation decomposition region as the second vaporous raw material mixture is the same as the first hydrogenation in the first vaporization reaction mixture. It is preferably at least about 5 ° C. above the temperature at which it exits the decomposition zone. Typically, the second injection temperature is at least about 10 ° C. higher, for example about 15 ° C. higher than the effluent temperature from the first hydrocracking zone. In most cases, the second injection temperature will be about the effluent temperature from the first hydrocracking zone.
It is unlikely that it will be high above 25 ℃.

The operating pressure is at least 3 bar, however about 30
It is preferably no higher than bar and most preferably in the range of about 15 to about 25 bar. Usually at least about 20 bar.

The two hydrocracking zones consist of separate reactors, each operating at approximately adiabatic conditions. Alternatively, the two hydrocracking zones consist of separate catalyst beds within the same reactor vessel.

The dialkyl esters of C ₄ dicarboxylic acids used in the process of the invention are preferably derived from alkyl alcohols containing 1 to 4 carbon atoms. Examples of such esters include diethyl maleate, diethyl fumarate, diethyl succinate, and mixtures of two or more thereof. Other suitable esters are the dimethyl, di- n -propyl, di- i -propyl, di- n -butyl, di- i -butyl, and di-sec-butyl of maleic acid, fumaric acid, and succinic acid. Esters, as well as mixtures thereof are included. Preferably the ester is selected from diethyl maleate, diethyl fumarate, diethyl succinate, and mixtures of two or more thereof.

Besides using undiluted ester as feedstock, it is also possible to use a solution of the ester in a suitable inert solvent, such as methanol, ethanol, or n- or iso-propanol.

It is desirable that the ester feedstock be pretreated, for example by distillation, to remove substantially all of the sulfite or halogenated impurities present in the feedstock. Further, it is preferable to remove almost all water.

The ester or ester solution feedstock is mixed with the recycled ester recovered in the product recovery section of the plant. If maleic acid, or fumaric acid di - is (C ₁ -C ₄ alkyl),
If used as a starting material, the product stream from the second hydrocracking zone thus contains a small amount of the corresponding dialkyl succinate. This is maleic acid or di- (C ₁ -C ₄ alkyl) fumarate, or a solution thereof, which is recycled as a new raw material to be supplied to the first hydrocracking zone by being recycled from the product recovery section of the plant. Mixed with. If the only target product is butane-1,4
If a diol, then all of the common product gamma-butyrolactone is recycled from the product recovery zone and mixed with fresh raw ester or ester solution. A convenient market for the common product butane-1,4-diol is usually supplied. The plant operator may adjust the operating temperature of the hydrocracking zone to meet the market requirements for butane-1,4-diol and gamma-butyrolactone, or for mixing with ester or ester solution feedstocks. , A portion of the gamma-butyrolactone product, or a portion of the butane-1,4-diol by-product, may be recycled from the product recovery zone to adjust the plant output.

The process requires that the presence of the starting ester and any other condensable components be in the gas phase in the first and second hydrocracking zones. Since the composition of the vaporous mixture must be controlled, at the selected operating conditions, the temperature of the mixture in contact with the catalyst is always above the dew point of the ester and other condensable components present. It means that. The temperature of the mixture in contact with the catalyst should always be preferably at least about 5 ° C, more preferably at least about 10 ° C, even more preferably at least about 15 ° C above the dew point of the mixture. This is usually accomplished by selecting the proper gas: Kester ratio in the vaporous mixture. A convenient method of forming a vaporous mixture for use in the method of the present invention is
Injecting a liquid ester or ester solution into a stream of hot hydrogen-containing gas so as to form a saturated or partially saturated vaporous mixture. Alternatively, such a vaporous mixture is obtained by bubbling a hot hydrogen-containing gas through the bulk of the liquid ester or ester solution. If a saturated vaporous mixture is formed, so as to form a partially saturated vaporous mixture prior to contacting the catalyst next,
It must be further heated or diluted with more gas.

Reduction of maleic acid or fumaric acid ester to gamma-butyrolactone involves the reaction of 3 moles of H ₂ with each mole of ester according to the equation below.

Where R is an alkyl group containing 1 to 4 carbon atoms.

However, when the succinate is hydrolyzed, only 2 moles of H ₂ are consumed.

Where R is the same as defined above.

The vaporous mixture usually contains excess hydrogen. In addition, it contains a small amount of carbon oxide. The vaporous mixture may further include a vaporized inert solvent (if used) and one or more inert gases (eg N ₂ ,
A, CH ₄ etc.) are included. It also contains vaporous material recycled from the product recovery area. If possible, supply hydrogen
It is preferably substantially free from compounds containing sulfur compounds, halogens such as Cl ₂ , and halogens such as HCL.

In the vaporous mixture, the H ₂ : ester molar ratio is typically at least about 50: 1 to about 1000: 1 or higher. Preferably at least about 150: 1 to about 500: 1. The presence of excess hydrogen and any inert gas that may be present serves to moderate the temperature rise in the first hydrocracking zone. In practice, the reduction of maleates such as diethyl maleate is more complicated than that suggested by equation (I) above, and as a result,
This results in the formation of indeterminate by-products including tetrahydrofuran, butane-1,4-diol and n -butanol. Although the reaction structure has not yet been fully elucidated, the evidence currently available is consistent with the series below.

The preferred catalyst used in the first and / or second hydrocracking zone is a reduced copper chromite catalyst. It must be conditioned with sufficient reduction of copper chromite before use. The catalyst should not react with H at temperatures above about 200 ° C.
_It is preferable to carry out reduction for a long period of time using a mixture of ₂ and an inert gas such as nitrogen, methane, or argon. Typical gases used in the reduction of the catalyst is, for example, of H ₂ N ₂ mixture containing at from about 1 to about 15% H ₂ capacity. Normal,
The catalyst is reduced for at least about 24 hours before use. The optimum effect is obtained when reduction is achieved at a temperature of about 120 ° C. to about 180 ° C. for several days before being used in the process according to the invention.
It is usually not necessary to carry out the reduction pretreatment for more than about 10 days.
If the catalyst is reduced at temperatures above 200 ° C., the activity is clearly inferior to that obtained with reductions carried out at lower temperatures. If the catalyst is fed in a pre-reduced state, the reduction period can be shortened. Higher H ₂ concentrations can be used in the latter half of the pretreatment. Thus, in the final stage of pretreatment of the reduction can be used of H ₂ instead of H ₂ / N ₂ mixture. High pressure is optimally used during this pretreatment. Pressures of, for example, 1 bar up to about 50 bar or higher can be used. After reduction treatment, the catalyst must be stored under an inert gas, hydrogen / inert gas mixture, or hydrogen until used.

The chemical formula of copper chromite can be represented by CuCr ₂ O ₄ . However, copper chromite is known to be non-stoichiometric and some authors have described, for example, copper chromite catalyst as CuO.
The chemical formula of CuCr ₂ O ₄ is expressed as copper chromium oxide. Thus, the catalyst may contain excess copper oxide. Additionally or alternatively, at least one stabilizer such as barium or manganese may be included in a trace amount. The catalyst is about 25 to about 45% by weight copper before reduction and about 20 to about 35% by weight
Contains chromium. The most preferred catalyst is about 32 by weight.
To about 38% copper and about 22 to about 30% by weight chromium. Such catalysts, if any,
It is preferred to include one or more stabilizers in an amount up to about 15% by weight. The catalyst may be supported by a suitable inert carrier. Desirably the catalyst is in a subdivided form,
At least about 30 m ² / g as measured by the well-known BET method, preferably it has an internal surface area of at least about 60 m ² / g. The catalyst is preferably a hollow cylindrical pellet or a conventional catalyst such as a ring-shaped or saddle-shaped catalyst.

Other catalysts used in the first and / or second hydrocracking zone of the process according to the invention may be found in International Patent Publication No.
It includes a reduced copper oxide / zinc oxide catalyst of the type disclosed in WO-A-82 / 03854.

Ester in the first hydrocracking zone from about 0.1 hr ^-1 to about
It is preferred to feed at a rate corresponding to the liquid hourly space velocity in the range of 0.6 hr ^-1 , or higher, for example up to about 1.5 hr ^-1 or even up to about 3.0 hr ^-1 . The term "liquid hourly space velocity" means the numerical value of the unit volume of liquid ester fed to the vaporization zone per unit volume of catalyst per hour. This is typically in the range of about 2500 hr ^-1 to about 16000 hr ^-1 , for example up to about 85000 hr ^-1 , most preferably about 8000 hr.
Corresponds to gas hourly space velocities in the range of ^-1 to about 30,000 hr ^-1 . The term "gas hourly space velocity" is the unit volume of vaporized mixture passing through a unit volume of catalyst per hour measured at 1 bar and 0 ° C.

Typically, the feed temperature to the second hydrocracking zone is at least about 190 ° C.

If required, further gas and / or ester may be mixed with the product stream from the first hydrocracking zone prior to entering the second hydrocracking zone to obtain a temperature or H ₂ :
The molar ratio of the ester may be adjusted. Also, one or more substances recovered in the product recovery area of the plant (eg, dialkyl succinate, unreacted maleic acid or dialkyl fumarate, gamma-butyrolactone and / or butane-1,4-diol). Instead of recirculating these materials to the inlet end of the first hydrocracking zone before entering the product stream from the first hydrocracking zone before entering the second hydrocracking zone. It is possible to add and mix.

Reduction of di- (C ₁ -C ₄ alkyl) maleate to the corresponding di- (C ₁ -C ₄ alkyl) succinate according to formula (III) above is an exothermic reaction. It was found that the yield of the tetrahydrofuran byproduct depends on the maximum temperature to which the reaction mixture is exposed in the hydrocracking zone and the residence time at high temperature, so that as the ester fed to the first hydrocracking zone, or succinic acid di as the main component of the ester - better to use the (C ₁ -C ₄ alkyl) is, the corresponding maleic or fumaric acid di - preferred than using (C ₁ -C ₄ alkyl). This is because this reduces the temperature rise in the first hydrocracking zone and thus the rate of formation of the tetrahydrofuran by-product.
Thus, in a particularly preferred method according to the present invention, maleic acid or fumarate or maleic acid or diethyl fumarate - (C ₁ ~C ₄ alkyl), most esters hydrogenolysis activity, or no catalyst or an ester, Using a catalyst stored under conditions such that hydrocracking and butane-1,4-diol formation are minimized, amber is used in the hydrogenation zone upstream of the first hydrocracking zone. Corresponding succinate di-, such as diethyl acid
Is hydrogenated (C ₁ -C ₄ alkyl). If necessary, before entering the first hydrogenolysis region, succinic acid di from upstream hydrogenation region - (C ₁ -C ₄ alkyl) reaction mixture containing is cooled, into the first hydrocracking region First, exothermic heat due to hydrogenation of C: C bond of maleic acid or fumarate is removed. In this way, the temperature rise in the first hydrocracking zone is kept as small as possible, so that the formation of tetrahydrofuran by-products is also minimal.

Maleic acid or fumaric acid di - when using (C ₁ -C ₄ alkyl), may be mentioned the following: Examples of catalysts that can be used upstream hydrogenation zone. International Patent Publication Number
Copper oxide / zinc oxide catalysts of the type disclosed in WO-A-82 / 03854, (supported) supported nickel, palladium,
Ruthenium and cobalt hydrogenation catalysts, zinc oxide, copper chromite catalysts, and copper chromite catalysts that have been carefully deactivated to reduce ester hydrogenolysis characteristics. When a copper chromite catalyst is used, it may or may not be inactivated, and maleic acid or fumaric acid di- (C ₁ -C ₄
Alkyl) at a relatively high rate to the upstream hydrogenation zone, for example at least about 1.0 hr ^-1 , preferably about 3.0 hr ^-1 to about 6.
It is suitable to supply at a rate corresponding to the liquid hourly space velocity of ⁰ hr ^-1 .

For convenience and simplicity of plant construction and operation, operation of any upstream hydrogenation zone to convert a dialkyl maleate and / or dialkyl fumarate to a dialkyl succinate,
It is preferable to carry out under substantially the same pressure as that used in the first and second hydrocracking zones. Therefore, typical operating pressures in the upstream hydrogenation zone are from about 3 bar to about 30 bar.
It is in the range of bar, preferably in the range of about 15 to 25 bar. Gas phase hydrogenation conditions are usually selected in the upstream hydrogenation zone. The inflow temperature to the upstream hydrogenation region is preferably suppressed to a temperature as low as practicable so as to be compatible with the vapor phase condition, and a range of about 160 ° C to about 180 ° C is typical. The capacity of the catalyst in the upstream hydrogenation zone is selected to provide the required high rate of ester feedstock processing.

The reaction mixture flowing out of the upstream hydrogenation zone is supplied to the first hydrogenolysis zone as a raw material mixture. Prior to being introduced into the first hydrocracking zone, the reaction mixture exiting the upstream hydrocracking zone is cooled somewhat to keep the inlet temperature as low as possible so that it can be used in the first hydrocracking zone, thus Limit the maximum temperature reached in. Further hydrogen and / or fresh feed ester and / or one or more substances recycled from the product recovery zone are introduced into the reaction mixture from the upstream hydrogenation zone before being introduced into the first hydrocracking zone. You may mix.

The product mixture exiting the second hydrocracking zone contains gamma-butyrolactone, in addition to unreacted hydrogen and possibly other gases, and an alkyl alcohol derived from the alkyl portion of the dialkyl ester starting material (eg, C ₁ -C ₄ alkyl alcohol) and a condensable mixture of substances. This condensable material also includes butane-1,4-diol, dialkyl succinate, and possibly a small amount of unreacted ester, and minor by-products including _n -butanol and tetrahydrofuran. These condensable substances are preferably condensed from the product mixture and separated by a suitable method, usually by distillation in one or more stages under normal, elevated or reduced pressure. In designing a suitable product recovery system, some of the components present in the product mixture may form an azeotrope with one or more other components in the product mixture. , It should be noted. While the liquid gamma-butyrolactone product and any butyrolactone formed are purified, any insignificant by-products may be used as fuel in the process. The alkyl alcohol can be recycled for reaction with more maleic anhydride or succinic anhydride, or more maleic acid, fumaric acid or succinic acid, and is recycled as used in the process of the invention. To form new dialkyl C ₄ dicarboxylic acid esters. Any unreacted ester starting material (eg, dialkyl maleate) and / or ester intermediate (eg, dialkyl succinate) can be recycled and mixed with the ester or ester solution feedstock. If desired, some of the gamma-butyrolactone and / or butane-1,4-diol byproduct may be recycled and mixed with the product stream from the first hydrocracking zone.

Unreacted hydrogen-containing gas from the product recovery stage can be recycled. A purge line may be used to control the level of inerts and / or byproducts in the circulating gas stream and in any liquid circuit.

To clearly understand the invention and to put it into practice in a simple manner, a preferred form of plant designed to carry out the method according to the invention will now be described, by way of example only, with reference to the accompanying drawings. . The figure is a flow diagram of a plant that accomplishes the hydrocracking of diethyl maleate.

Those skilled in the art will appreciate that the drawings are schematic and that more equipment is required in a commercial plant, such as temperature and pressure sensors, valves, control equipment and the like. Providing accessories for such equipment does not form any part of the invention,
It follows conventional chemical industry practices. Furthermore, the heat exchange equipment in the illustrated plant is merely one way of achieving the desired temperature levels, and other equivalent heat exchange systems may be used instead.

In the figure, diethyl maleate is fed in line 1 and mixed with the liquid recycle stream in line 2 containing diethyl succinate and possibly gamma-butyrolactone and / or butane-1,4-diol. The mixed liquid flow is
The material is supplied to the raw material heater 4 by the pump 3 and heated there to 245 ° C. by the steam supplied from the line 5. The resulting hot liquid stream goes to the spray nozzle 6 of the feed saturator 7, where the resulting spray is:
It collides with an ascending stream of hot hydrogen-containing gas supplied at lines 8 to 25 bar. The liquid flows out from the bottom of the raw material saturator 7 by a line 9, is sucked up by a circulation heater 11 by a raw material saturator pump 10, and is re-sprayed to the raw material saturator 7 via a nozzle 12. Reference numeral 13 indicates a spray removal pad on the upper part of the raw material saturator 7. Ester vapor mixed flow in line
The raw material saturator 7 is discharged from 14 and the steam heater 15 is advanced to where the temperature is raised to 190 ° C. The H ₂ : ester molar ratio is approximately 200: 1. This mixture then contains, in a substantially adiabatic reaction state, about 25% by weight copper and about 35% by weight chromium, and a first bed 16 of copper chromite catalyst having a surface area of 85 m ² / g. pass. The vaporization reaction mixture comprises about 20 for the first bed 16.
It flows out at an outflow temperature of 5 ° C. Analysis of this first reaction mixture shows the absence of diethyl maleate, hydrogen and an inert gas (eg CO, CO ₂ , methane, propane, N ₂ which would be present in the hydrogen supply to the plant). , Ar,
And other inert gases), the first reaction mixture was found to contain significant amounts of diethyl succinate, ethanol, tetrahydrofuran, n -butanol, gamma-butyrolactone and butane-1,4-diol. ing.
In the process of passing through the first bed 16 in a substantially adiabatic reaction state used in this method, diethyl maleate is smoothly and quantitatively sufficiently converted to diethyl succinate, and then diethyl succinate is converted into ethanol, tetrahydrofuran, It is converted to a product containing n -butanol, gamma-butyrolactone, and some non-critical byproducts. 1st floor 16
The amount of catalyst charged in (1) is related to the feed rate of vaporized diethyl maleate to the first bed 16 and is appropriately selected, so that the reaction can reach a nearly equilibrium state in the first bed 16. First floor
The feed rate of vaporized diethyl maleate to 16 is about 0.45 hr ^-1
Corresponds to liquid hourly space velocity.

The vaporous first reaction mixture exits the first bed 16 at about 205 ° C and passes via line 17 to the heat exchanger 18 where it is at 215 ° C.
Second bed of the same copper chromite catalyst
Proceed to 19. Further hydrogenation reaction is carried out in the course of passing through the bed 19 and the reaction mixture re-equilibrates to a second reaction mixture containing a higher molar ratio of gamma-butyrolactone: butane-1,4-diol than the first reaction mixture. Occurs. The capacity of the catalyst in the second bed 19 is approximately twice the amount in the first bed 16. Therefore, the rate at which vaporized diethyl maleate is supplied to the first bed 16 corresponds to about 0.15 hr ⁻¹ liquid hourly space velocity measured through both beds 16, 19.

The second reaction mixture passes through line 20 to heat exchanger 21 and then to product cooler 22 where it is cooled by the cooling water supplied in line 23 and further to product catch pot 24.
Proceed to. The gas exits line 26 while the liquid condensate is recovered by line 25. Liquid condensate pressure reducing valve
27 to a vacuum catch pot 28, and from there to a product recovery section 29, where the butane-1,4-diol product is gamma-butyrolactone, tetrahydrofuran, ethanol, n -butanol, succinic acid. Separated from diethyl and from other non-critical components present in the condensate. Separation of the condensate in the product recovery unit 29 is obtained by the following method. For example, tetrahydrofuran, ethanol, n -butanol, and other low-boiling by-products are removed to remove "light ends".
s) ”distillation steps, including a distillation step, and then a product from the top consisting of an azeotrope of the resulting bottom product gamma-butyrolactone and diethyl succinate,
A bottom product consisting of butane-1,4-diol, resulting in a distillation. The azeotrope of gamma-butyrolactone / diethyl succinate can be separated by distillation using a distillation column filled with water. Tetrahydrofuran is recovered in line 30, gamma-butyrolactone in line 31, and butane-1,4-diol in line 32. Some of the diethyl succinate and possibly butane-1,4-diol and / or gamma-butyrolactone are recycled in line 2.

Fresh hydrogen is supplied to the plant via line 33 and compressor 34
And via a cooler 35 to be mixed with the recycled gas in line 26. The mixed gas stream is compressed in recirculation compressor 36 and fed to line 8.

The gas purge stream is absorbed in line 37 after passing through pressure reducing valve 38 and mixed with the vent stream in line 39 from catch pot 28. The mixed stream in line 40 goes to a gas purge condenser 41, which is supplied with coolant in line 42 from the cooling device 43. Any condensate is recovered in line 45 and supplied to product recovery section 29 while purge gas exits in line 44. Line 46 from the bottom of raw material saturator 7 if necessary
Can be purged with.

For those skilled in the art, the plant shown in the figures shows that, with relatively minor modifications, instead of diethyl maleate as a feedstock, other C ₄ dicarboxylic acids such as diethyl succinate or a mixture of diethyl maleate and diethyl succinate can be used. It will be readily appreciated that one can work with dialkyl esters of acids. However, some design modifications to the product recovery section 29 may be required. Such diethyl succinate or a mixture thereof with diethyl maleate may be produced from diethyl maleate by hydrogenation in, for example, an upstream hydrogenation zone (not shown). The product of the upstream hydrogenation zone is fed by line 1 to the illustrated plant.

In another variant of the plant shown, diethyl maleate fed in line 1 is converted to diethyl succinate in the gas phase in the upstream hydrogenation zone (not shown) in line 14 upstream from the first hydrocracking zone. Hydrogenated. Such an upstream hydrogenation zone preferably contains, for example, a relatively low loading of copper chromite catalyst, and the rate at which the ester passes therethrough corresponds to at least about 3.0 hr ^-1 liquid hourly space velocity. The resulting hydrogenated ester containing reaction mixture now contains only traces of diethyl maleate and butane-1,4-diol, respectively, and a large amount of diethyl succinate, but the first hydrogenolysis It is cooled prior to entering region 16 to remove the exotherm of hydrogenation of the C: C bond of the unsaturated ester starting material.

Front Page Continuation (72) Rasmel Colin, Inventor, Cleveland, Yarm, Muntraven Road 7 (72) Inventor, Kipax John Wilson UK, North Yorkshire Deer 8 2 Peda Beedale, Farby, John Krafham House (No house number) (72) Inventor Carter Anthony Benjamin Cleveland, Stockton-on-Tees, Norton, Weston Crescent 37 (72) Inventor Scarlett John United Kingdom, County Durham Diel 16 7 Jette Spennymoor, Kirk Merling Cleveland View 2 (72) Inventor Reason Arthur James From Cleveland, Middlesbrough, Akram, Mia Seed Sands 30 (72), England Who Harris Norman UK, Cleveland, Norton Grantham load 22 (56) Reference Tokuoyake Akira 48-823 (JP, B1) Tokuoyake Akira 49-31434 (JP, B1)

Claims (13)

[Claims] 1. A method for producing gamma-butyrolactone by hydrogenolysis of a dialkyl ester of C ₄ dicarboxylic acid, wherein first and second hydrogenolysis zones are provided, and each zone is composed of copper chromite. Including a homogeneous ester hydrocracking catalyst charge to the first hydrocracking zone at elevated pressure, above the threshold temperature for the hydrocracking reaction, at a elevated first feed temperature, in gaseous form. of
Providing a first vaporous feed stream comprising a dialkyl ester of C ₄ dicarboxylic acid and excess hydrogen, the hydrogen: ester molar ratio being in the range of about 50: 1 to about 1000: 1, In the 1-hydrogenolysis region, hydrogenolysis is carried out under substantially adiabatic reaction conditions, whereby hydrogen is substantially liberated from the initiating ester and, in addition to unreacted hydrogen, a first molar ratio of gamma-butyrolactone and butane-1, Forming a vaporous first reaction mixture comprising 4-diol, a vaporous first reaction mixture
Heating the reaction mixture, the resulting second vaporous feedstock stream comprising the heated vaporous first reaction mixture is introduced into a second hydrocracking zone to a threshold temperature for the hydrocracking reaction. Supply at a second raw material temperature exceeding
Further reacting and equilibrating the second vaporous raw material stream in the second hydrogenolysis zone under substantially adiabatic reaction conditions;
A second vapor reaction comprising, from the hydrocracking zone, unreacted hydrogen and a second molar ratio of gamma-butyrolactone and butane-1,4-diol that is greater than the first molar ratio. A method comprising: recovering a mixture. 2. The copper chromite catalyst comprises, prior to reduction, about 25 to about 45% by weight copper and about 20 to about 35% by weight chromium. The method according to claim 1. 3. A method according to claim 1 or 2 wherein the first feedstock temperature is in the range of about 170 ° C to about 260 ° C. 4. The method of claim 3 wherein the first feed temperature is about 190 ° C to about 230 ° C. 5. The second feedstock temperature is at least about 5 ° C. above the temperature at which the vaporous first reaction mixture exits the first hydrocracking zone. Item 5. The method according to any one of items 4 to 4. 6. The method according to claim 1, wherein the second raw material temperature is at least about 190 ° C. 7. The method of any of claims 1-6, wherein the first feedstock temperature is at least about 5 ° C. above the dew point of the first vaporous feedstock stream. 8. A method according to any one of claims 1 to 7 wherein the second feed temperature is at least about 10 ° C above the dew point of the second vapor feed stream. 9. Atmospheric pressure is in the range of about 3 bar to about 30 bar.
The method according to any one of paragraphs. 10. The ester enters the first hydrogenolysis zone,
Any one method according to Claims first term - Section 9, characterized in that from about 0.1 hr ^-1 is supplied at a rate corresponding to a liquid hourly space velocity of about 0.6hr ^-1. 11. Esters, di C ₄ dicarboxylic acid - (C ₁
-C ₄ alkyl) any one method according to Claims Section 1 - paragraph 10, characterized in that an ester. 12. A process according to claim 11, characterized in that the ester is selected from diethyl maleate, dialkyl fumarate and mixtures thereof. 13. A process according to claim 11, characterized in that the ester is selected from diethyl succinate and mixtures thereof with the addition of one or both of diethyl maleate and diethyl fumarate.