DE102009027420A1 - Preparation of acrolein or aqueous acrolein solution comprises dehydration of a cyclic acetal of glycerol in the presence of a solid catalyst comprising acidic oxides or mixed oxides, natural or synthetic silicate materials - Google Patents

Abstract

Preparation of acrolein or aqueous acrolein solution comprises dehydration of a cyclic acetal of glycerol.

Description

Field of the invention

object The invention is a process for the preparation of acrolein by Dehydration of a cyclic acetal of glycerol.

State of the art

The production of acrolein from glycerol by dehydration of glycerol is widely described in the literature. There are a variety of methods using a variety of conditions and mostly acidic catalysts known. Examples include: JP2008195643 . JP2008162908 . JP2008137950 . JP2008137949 . WO2008140118 . WO2008066082 . WO2007132926 . WO2006087084 . WO2006087083 . CN101070276 . EP2006273 . EP0598229 , Disadvantage of these methods is that only pure glycerol can be fed into the process.

WO2007090990 describes a process for the production of acrolein by the oxidation of propylene.

US4851583 describes a process for the preparation of acrolein from acrolein acetals.

The preparation of acetals from polyols and aldehydes is described, inter alia, in Beyer Walter, Textbook of Organic Chemistry, S. Hirzel Verlag, Stuttgart, 1984 , described; Often this reaction is used as protection group technology.

FR2869232 describes the preparation of pharmaceuticals based on, for example, cyclic acetals prepared from glycerol and short-chain aldehydes.

Publications by Tink and Neish (Can. J. Technol. 29 (1951) 243-249; ibid 250-261; ibid 268-275) describe the reactive extraction of glycerol to form acetals of glycerol.

WO2008043947 describes the preparation of cyclic acetals from glycerol and aldehydes, ketones or linear acetals as well as the purification of the cyclic acetals.

task The invention was to provide a method with which Acrolein resource-saving, for example through the use of renewable Raw materials, such as crude glycerine from biodiesel production or glycerol-containing By-products from fermentations, are produced as starting material can.

Description of the invention

Surprisingly was found that the procedures described below the solve the problem posed by the invention.

One Advantage of the present invention is that the inventive Procedure carried out at a significantly lower water concentration can be, as a method of the prior art, in which the Acrolein obtained directly from a dehydration of glycerol is, so is also an increased educt concentration in front. This also advantageously reduces the necessary energy input, since the water is thermally separated for the purification of the acrolein must become.

Further Advantages of the present invention compared to methods of Prior art in which the acrolein from a dehydration of the glycerol is obtained directly, are a high catalyst life and high selectivity at near full conversion the method according to the invention.

Yet an advantage of the method according to the invention it is that if the cyclic acetal of glycerine is made up for example Rohglycerin is obtained, a previous complex purification of glycerol is omitted, which for direct cleavage of the Glycerol in acrolein is inevitable. This allows necessary apparatus and energy of the formerly necessary purification of glycerol saved at the same high selectivity become.

Likewise, it is advantageous that the directly available in the inventive method aqueous Acroleinlösung without further workup or purification of the use can be supplied.

object The present invention is a process for the preparation of Acrolein or aqueous acrolein solution by dehydration a cyclic acetal of glycerol.

wobei R¹ gegebenenfalls substituierte, verzweigte oder unverzweigte, gesättigte oder ungesättigte organische Reste mit 1 bis 11, bevorzugt 1 bis 8, besonders bevorzugt 1 bis 5 Kohlenstoffatomen, oder H und
R² gegebenenfalls substituierte, verzweigte oder unverzweigte, gesättigte oder ungesättigte organische Reste mit 1 bis 11, bevorzugt 1 bis 8, besonders bevorzugt 1 bis 5 Kohlenstoffatomen, oder H.Cyclic acetals of glycerol are described for example by compounds of the general formula I and II, these compounds are often in equilibrium with each other before. The process according to the invention is therefore preferably characterized in that the cyclic acetal of the glycerol is selected from the group comprising compounds of the general formula I and II or mixtures thereof

where R ^{1 is} optionally substituted, branched or unbranched, saturated or unsaturated organic radicals having 1 to 11, preferably 1 to 8, particularly preferably 1 to 5 carbon atoms, or H and
R ^{2 is} optionally substituted, branched or unbranched, saturated or unsaturated organic radicals having 1 to 11, preferably 1 to 8, particularly preferably 1 to 5 carbon atoms, or H.

It is apparent that when one of the substances of the general formula (I) or (II) is described as the tautomeric equilibrium, R ^{1 is the} same as R ² .

In the case of the substituted organic radicals R ¹ and R ² , a substitution with OH is preferred; In particular, it is preferred here that R ¹ or R ^{2 is} determined by an acetal obtainable by the acetalization of glycerol with 3-hydroxypropionaldehyde.

In particular, it is also preferred here that R ¹ or R ^{2 is} determined by an acetal obtainable by the acetalization of glycerol with the industrially readily accessible compounds selected from the group comprising formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, valeraldehyde, Isovaleraldehyde, heptanal, nonanal and isononanal.

about In addition, it is preferred that in the inventive Process the cyclic acetal of glycerin in concentrations from 1-100% by weight, preferably 20-95% by weight, especially preferably 50-90 wt .-% based on the total educt weight is used.

It has been further found that by the presence of Water in the process of the invention essential longer catalyst life can be achieved; Therefore, it is preferred in the inventive method, that the dehydration with a mixture containing water and the cyclic acetal of glycerol is carried out, wherein a water content of 0-90% by weight, preferably of 5-80% by weight, most preferably from 5-49% by weight, based on the total Mixture is preferred.

The inventive method can be in the liquid phase or in the gas phase.

The Reaction in the gas phase is particularly preferred because of the conversion of the cyclic acetal is very high and leaving the process gaseous reaction mixture to obtain an aqueous Acrolein solution, which additionally formed by-products contains, can be condensed immediately; this condensate can often be further processed directly. Provided desired, may be from the reaction mixture acrolein, optionally together with one part of water, by distillation or fractionated Condensation can be won; the acrolein-free reaction mixture In turn, the dehydration can be recycled.

Furthermore may be the dehydration in the gas phase under continuous Conditions are performed.

It is preferred in the reaction in the gas phase as a carrier gas Nitrogen use, since this is easily accessible.

In the case of the reaction in the liquid phase, it is expedient to carry out the dehydration only up to a limited conversion of the cyclic acetal, since with an increase in the conversion the selectivity may decrease. After reaching the advantageous conversion formed acrolein alone or together with part of the water in a known manner, usually by distillation or by an N ₂ -Strippung separated from the reaction mixture. The acrolein can be isolated by condensation or a wash with water. The reaction mixture containing the acrolein-free cyclic acetal is recycled to the dehydration step. An advantage of the dehydration in the liquid phase over that in the gas phase is the lower energy consumption, because only the separated from the reaction mixture acrolein and a transitional part of water must be evaporated. Dehydration in the liquid phase can be carried out under continuous conditions.

The Dehydration is preferably carried out in the temperature range between 150 and 450 ° C, preferably between 200 and 400 ° C, especially between 250 and 350 ° C.

Furthermore the dehydration is preferably carried out in the pressure range between 0.1 and 200 bar, preferably between 0.5 and 50 bar, more preferably between 0.9 and 10 bar. In the case of liquid phase dehydration the apparatus is subjected to at least one such pressure, necessary to maintain the liquid phase is.

In In a particular embodiment, the dehydration takes place at a given atmospheric pressure, d. H. at normal pressure and depending on the location on earth at about 1 bar, and in the temperature range between 250 and 350 ° C.

the It is known to a person skilled in the art that chemical reactions can be selected by choosing suitable Catalysts can be controlled and influenced; in the method according to the invention can all catalysts are used which are capable of the dehydration reaction to accelerate the process according to the invention, such can be selected, for example from the group comprising Bronsted acids and Lewis acids.

When Catalysts thus come liquid and solid catalysts into consideration, whereby the aggregate state "fixed" both includes amorphous as well as crystalline structures.

It was found in this context that it is beneficial if the dehydration in the presence of a solid catalyst, preferably an acidic, is performed.

Suitable acidic solid catalysts are in particular the DE 10 2007 004 351 A1 and the EP0598229 to the disclosure of which is explicitly stated here.

Further Preferred solid catalysts are especially acidic oxides and mixed oxides, natural and synthetic siliceous Substances, in particular mordenite, montmorillonite and acid zeolites such as H-ZSM5, MCM-22, zeolite beta.

As suitable solid catalysts also come to support materials immobilized acids and their salts into consideration. Such acids and their salts are preferably selected from the group comprising:
mono-, di- or poly-protic inorganic acids, in particular phosphoric acid, sulfuric acid, boric acid; Transition metal-containing acids, in particular of vanadium, tungsten, molybdenum, rhenium, and also their modifications such as tungsten silicic acid, tungsten phosphoric acid, tungsten oxides, or their heteropolyacids; strong organic acids such as sulfonic acids or halogenated carboxylic acids such as trifluoroacetic acid; Lewis acids such as AlCl ₃ .

When Support materials for in the inventive Solid catalysts used can acidic, neutral and basic materials are used, with the top described solid catalysts themselves as a carrier material for the acids to be immobilized or their Salts can be used and acidic support materials are preferred.

Preferred support materials are oxidic substances, for example Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ and mixed oxides (binary, ternary or higher), such as γ-Al ₂ O ₃ and ZnO Al ₂ O ₃ , SiO ₂ -Al ₂ O ₃ , ZrO ₂ -SiO ₂ , ZrO ₂ -HfO ₂ mixed oxides. The carriers serve primarily to increase the specific surface area and to fix the active sites, but may also themselves have dehydration properties.

It the expert is apparent that mixtures of the catalysts and Mixtures of the support materials can be used.

Other suitable solid catalysts comprising a support material and immobilized acid are ion exchanger, preferably acidic ion exchanger, such as sulfonic acids fluorpolymergeträgerte that are available under the trade name Nafion ^®.

When other ingredients may be one or more of the catalyst Promoters are added. These accelerate the regeneration of the catalyst, and cause an increase in the service life and space-time yield by a lower coking tendency of the catalyst. As promoters can compounds in particular of the elements of the first and second main group and rare earth metals such as cerium, or transition metals such as copper, silver, gold, iron, cobalt, nickel, ruthenium, rhodium, Palladium, platinum in metallic form or used as compounds become.

In the two embodiments, based on whether the dehydration is carried out in the gas phase or liquid phase, can in principle be the same acidic solid catalysts be used; However, it has been shown that certain catalysts preferably for dehydration in the gas phase and others, preferably those in the liquid phase, are suitable.

For inventive method must be the cyclic Acetal of glycerol can be provided.

• A) Umsetzen einer Glycerin enthaltenden Lösung mit mindestens einer Carbonylverbindung unter Erhalt eines zyklischen Acetals und gegebenenfalls
• B) Aufreinigung des in Verfahrensschritt A) erhaltenen zyklischen Acetals.

This is preferably carried out by obtaining the cyclic acetal of glycerol by a process comprising the process steps:

• A) reacting a glycerol-containing solution with at least one carbonyl compound to obtain a cyclic acetal and optionally
• B) Purification of the cyclic acetal obtained in process step A).

An exemplary reaction of method step A) might look something like this

The inventive method allows in process step A) the use of aqueous solutions, therefore it is preferred that the glycerin-containing solution in process step A) is an aqueous solution.

hereby is the use of raw glycerine, as in the case of biodiesel production obtained as non-purified glycerol possible. Also possible is the use of crude glycerol from fermentation processes, as for example in ethanol production as a by-product accrues.

Therefore it is preferred that the glycerin-containing solution in process step A) is crude glycerol.

The used in process step A) carbonyl compound is preferred selected from the group comprising aldehydes, ketones, wherein it is preferable that the carbonyl compound has a carbon atom number with 1 to 12, preferably 1 to 9, particularly preferably 1 to 6 carbon atoms is.

in the Case of substituted carbonyl compounds is a substitution preferred with OH; In particular, here is preferred carbonyl compound 3-hydroxypropionaldehyde.

Further, due to their good availability in process step A) also preferably used carbonyl compound are selected from the group comprising formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, Isobutyraldehyde, valeraldehyde, isovaleraldehyde, heptanal, nonanal and isononanal.

As in the dehydration, it is advantageous that in process step A) an acid is used as a catalyst.

When Catalyst used acids in process step A) may be a solid acid as a heterogeneous Catalyst or a mineral acid as a homogeneous Catalyst can be used.

In Process step A) is preferably a homogeneous catalyst Acid selected from the group comprising hydrochloric acid, Nitric acid, sulfuric acid, methanesulfonic acid, Paratoluene sulfonic acid, trifluoroacetic acid and Oxalic acid used.

In Process step B) can all be known to the person skilled in the art Purification process for low-molecular substances be used. Exemplary are at this point the precipitation by means of suitable solvents, the extraction by means of suitable solvents, the complexation, for example by means of cyclodextrins or cyclodextrin derivatives, crystallization, the purification or isolation by means of chromatographic methods called.

It it is recommended in process step B) a reactive extraction for Use purification of the cyclic acetal of glycerol.

Around to use resource-conserving is used for the acetalization Carbonyl compound after dehydration of the cyclic acetal recovered from the dehydration reaction mixture and preferably the method according to the invention fed again.

In The examples below are the present Invention described by way of example, without the invention, whose Scope of application is apparent from the entire description and the claims, limited to the embodiments mentioned in the examples should be.

All Percentages are by weight unless otherwise specified.

Examples:

The used hereinafter "Nml / min" means ml / min at 25 ° C and 1 bar.

Example 1: Reactive extraction of the cyclic Acetals with an extractant

• Catalyst: Amberlite IR-120 (H ⁺ ), 60g / L, T: 20 ° C, Aldehyde / Glycerol: 1/1 [mol / mol], Phase Ratio: Organic / Aqueous: 1/1 [g / g]

0.91 g of glycerol in 3.64 g of water are placed in a mixing cell and 0.45 g of acetaldehyde are added. Next, 5 g of o-xylene are added, the mixture with 0.6 g of neutral-washed, dried Amberlite IR-120 (H ⁺ -form) and stirred at 20 ° C for 2.5 h. The yield of acetals formed is 91%, the distribution coefficient D _eff is 0.74 and indicates the ratio of dissolved in the organic phase glycerol and acetal to the dissolved in the aqueous phase glycerol and acetal masses.

Example 2: Reactive extraction of the cyclic Acetals, wherein the carbonyl compound acts as an extraction agent

• Catalyst: Amberlite IR-120 (H ⁺ ), 60 g / L, T: 20 ° C, aldehyde / glycerol: 6.4 / 1 [mol / mol], phase ratio: organic / aqueous: 1/1 [g / g ]

In a mixed cell, 1.0 g of glycerol in 4.0 g of water are introduced and 5.0 g of butyraldehyde is added. The mixture was treated with 0.6 g of neutral-dried, dried Amberlite IR-120 (H ⁺ form) and stirred at 20 ° C. for 2.5 h. The yield of formed acetals is 97%, the distribution coefficient D _eff is 6.54.

Example 3: Cleavage C2-acetal:

0.3 g of catalyst are fixed in a continuously operated fixed bed reactor and heated to 300 ° C. under a stream of nitrogen (5 N ml / min). Upon reaching the temperature stability, the feed stream is fed to a mixture of vaporized C2-acetal (5% by volume) and nitrogen (95% by volume) to carry out the reaction switched.

After an operating time of 2 h, the Flüssigfeedstrom is turned off, changed to air and heated to 400 ° C, whereby the catalyst is regenerated. After cooling to 300 ° C, the catalyst is again loaded with acetal. The reaction / regeneration cycles are repeated 40 times. Table 1 TOS h T ° C Flow Nml / min Feed Vol% reaction 2 300 5 5% C2-acetal + 95% N ₂ Warm up 0.5 300-400 5 17% O ₂ + 83% N ₂ regeneration 1 400 5 17% O ₂ + 83% N ₂ cooling down 1 400-300 5 17% O ₂ + 83% N ₂

The yield at the end of the experiment for H ₃ PO ₄ / TiO ₂ and NiSO ₄ as catalyst: TABLE 2 Results TOS 1 h 20 h 80 h 160 h Yield acrolein (H ₃ PO ₄ / TiO ₂ ) [%] 45 25 22 5 Yield acrolein (NiSO ₄ ) [%] 38 12 8th 10

Example 4: Cleavage C4-acetal:

It are 0.3 g in a continuously operated fixed bed reactor Fixed catalyst and under a stream of nitrogen (5 N ml / min) heated to 300 ° C. When temperature stability is reached the feed stream is added to a mixture of vaporized C4-acetal (4 Vol%), water vapor (7% by volume) and nitrogen (89% by volume) switched.

After 40 hours TOS (= time on stream, service life of the catalyst), the experiment is terminated. With 8% H ₃ PO ₄ / SiO ₂ as catalyst, the following results are obtained without regeneration (Table 3): TABLE 3 Results TOS 5 h 20 h 30 h 40 h Conversion (C4-acetal) [%] 100 100 90 60 Yield (acrolein) [%] 85 85 65 35 Yield (butyraldehyde) [%] 100 90 75 50 Yield (acetaldehyde) [%] 2 1.5 1 1 Carbon balance [%] 95 83 82 85

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - JP 2008195643 [0002]
• - JP 2008162908 [0002]
• - JP 2008137950 [0002]
• - JP 2008137949 [0002]
• - WO 2008140118 [0002]
• - WO 2008066082 [0002]
• WO 2007132926 [0002]
• WO 2006087084 [0002]
• - WO 2006087083 [0002]
• - CN 101070276 [0002]
• - EP 2006273 [0002]
• - EP 0598229 [0002, 0033]
• - WO 2007090990 [0003]
• - US 4851583 [0004]
• - FR 2869232 [0006]
• - WO 2008043947 [0008]
• DE 102007004351 A1 [0033]

Cited non-patent literature

• - Beyer Walter, textbook of organic chemistry, S. Hirzel Verlag, Stuttgart, 1984 [0005]
• Publications by Tink and Neish (Can. J. Technol. 29 (1951) 243-249, ibid 250-261, ibid 268-275) [0007]

Claims (17)

Process for the preparation of acrolein or aqueous Acrolein solution by dehydration of a cyclic Acetals of glycerin. A method according to claim 1, characterized in that the cyclic acetal of glycerol is selected from the group comprising the compounds of general formula I and II or mixtures thereof

wherein R ¹ optionally substituted, branched or unbranched, saturated or unsaturated organic radicals having 1 to 11, preferably 1 to 8, particularly preferably 1 to 5 carbon atoms, or H and R ² optionally substituted, branched or unbranched, saturated or unsaturated organic radicals 1 to 11, preferably 1 to 8, particularly preferably 1 to 5 carbon atoms, or H. A method according to claim 1 or 2, characterized in that the cyclic acetal of glycerol in Concentrations of 1-100% by weight, preferably 20-95 Wt .-%, particularly preferably 50-90 wt .-% based on the total educt weight is used. Method according to at least one of claims 1 to 3, characterized in that the Dehydration with a mixture containing water and the cyclic Acetal of glycerol is performed. Method according to at least one of claims 1 to 4, characterized in that the Dehydration in the gas phase under continuous conditions is carried out. Method according to at least one of claims 1 to 5, characterized in that the Dehydration in the temperature range between 150 and 450 ° C is carried out. Method according to at least one of claims 1 to 6, characterized in that the Dehydration in the pressure range between 0.1 and 200 bar performed becomes. Method according to at least one of claims 1 to 7, characterized in that the Dehydration at a given atmospheric pressure and in the Temperature range between 250 and 350 ° C performed becomes. Method according to at least one of claims 1 to 8, characterized in that the Dehydration carried out in the presence of a solid catalyst becomes. A method according to claim 9, characterized characterized in that the solid catalyst is selected is from the group comprising acidic oxides and mixed oxides, natural and synthetic siliceous substances. A method according to claim 9 or 10, characterized in that the solid catalyst on support materials immobilized acid or salts of an acid. Method according to at least one of claims 9 to 11, characterized in that the Solid catalyst contains at least one promoter. A method according to any one of claims 1 to 12, characterized in that the cyclic acetal of glycerol is obtained by a method comprising the steps of: A) reacting a glycerol-containing solution with at least one carbonyl compound to obtain a cyclic acetal and optionally B) Purification of the cyclic acetal obtained in process step A). A method according to claim 13, characterized in that the glycerol-containing solution is an aqueous Solution is. A method according to claim 13 or 14, characterized in that in process step A) an acid used as a catalyst, Method according to at least one of claims 13 to 15, characterized in that the Purification in process step B) used a reactive extraction becomes. Method according to at least one of claims 13 to 16, characterized in that the in process step A) used carbonyl compound from the reaction mixture the dehydration back and the process is fed again.

Images