WO2016110520A1

WO2016110520A1 - Method for producing succinic acid anhydride and high purity succinic acid or esters or amides thereof

Info

Publication number: WO2016110520A1
Application number: PCT/EP2016/050157
Authority: WO
Inventors: Alexander DÜFERT; Rolf Pinkos; Wolf-Steffen Weissker
Original assignee: Basf Se
Priority date: 2015-01-09
Filing date: 2016-01-07
Publication date: 2016-07-14

Abstract

The invention relates to a method for producing succinic acid anhydride and high purity succinic acid or esters or amides thereof from raw succinic acid which can be obtained by converting biomasses, by transforming the succinic acid into succinic acid anhydride and optionally transforming the succinic acid anhydride to form succinic acid, by separating unwanted secondary components.

Description

Process for the preparation of succinic anhydride and high purity succinic acid or their esters or amides

description

The invention relates to processes for the preparation of succinic anhydride and highly pure succinic acid or their esters or amides from succinic acid, which was obtained by reacting biomass, by conversion of succinic acid in succinic anhydride and optionally converting the succinic anhydride to succinic acid, with removal of interfering secondary components.

The production of succinic acid from biomass is described, for example, in WO 2010/092155 A1. Furthermore, this WO also describes the further use of succinic acid or its diester for obtaining THF, butanediol and / or gamma-butyrolactone, the esters being obtained, for example, by reactive distillation esterification of diammonium succinate. Otherwise, salts of succinic acid are converted into free succinic acid by acidic ion exchangers, which are then regenerated with HCl, for example. The purification of this succinic acid thus obtained is then carried out by concentration and crystallization. In Example 9, the purity of succinic acid is given as 99.8%. It is not described which impurities are contained. Succinic anhydride is not mentioned.

The production of succinic anhydride from succinic acid is known per se. DE-1 141 282 B describes the preparation of succinic anhydride by adding liquid succinic acid to a column, wherein water distils off overhead and the anhydride is obtained at a purity of 95-97% from the bottom. Nothing is said about the impurities. According to FR 1 386 278 succinic acid is dewatered by distillation, the anhydride remaining in the residue. According to Org. Lett. 2011, 13, 892 succinic acid is formed in a homogeneous-catalyzed process with the catalyst as a high boiler; the purification is carried out by precipitation of the anhydride and filtration of the reaction mixture.

JP 2003 1 13 3171 A describes the purification of succinic anhydride by distillation, wherein in the distillation of the succinic acid to avoid discoloration of the product, the bottom temperature at a reduced pressure between 125 and 200 ° C. Only dilactones are described as impurities to be avoided. Not mentioned is the production of succinic anhydride by succinic acid obtained by fermentative processes.

Unlike products made by classical chemical reactions, the particularity of products obtained from biomass is due to the disproportionately high number of minor components that may interfere with subsequent applications, especially when long chain length polymers are to be formed which monofunctional groups disrupt the construction of chains. In the present case, the main uses of succinic acid or succinic anhydride are, for example, the preparation of THF and from it polytetrahydrofuran or, via the hydrogenation to 1,4-butanediol, the preparation of polyesters. Tern or polyurethanes and by esterification with polyols, the production of polyamic acid esters or by reaction with polyamines to Polybernsteinsäureamiden. Furthermore, secondary components can interfere with the catalysts in terms of selectivity and yield of the process, but above all have a negative effect on the service life of the catalysts. Examples of these interfering secondary components, which may be harmful even in amounts below 1 ppm by weight, are the elements N, P, S, As, Sb, Bi, Sn and halogens such as Cl, Br and I.

N-containing compounds, especially if they have basic properties, can occupy acidic sites on catalysts and thus destroy desired properties. In particular, the nitrogen-containing compounds are detrimental if, for. B. undergo a hydrogenation step, since many of them are only to basic acting compounds. This can then hinder the hydrogenation step or subsequent processes. Here, in turn, the polymerization of THF is negatively affected, since this is usually carried out in the presence of acidic catalysts. In particular, in the hydrogenation of succinic anhydride in the presence of N-containing compounds, in particular ammonia or those which can release them, pyrrolidine can easily arise, which hinders the hydrogenation process and due to its boiling point similar to THF is difficult to separate from this, and later the polymerization interferes. Furthermore, such N-containing components are detrimental to the production of polysuccinic acid esters because they can block a free end of succinic acid and thus hamper chain growth. In addition, N-containing impurities may compete with an added amine in the production of succinic amides and unintentionally lead to a copolymer. Compounds containing P, S, As, Sb, Bi, Sn or halogens such as Cl, Br and I are undesirable because some of them are not only toxic to the environment but can also poison hydrogenation catalysts. Many of these compounds are volatile, so that they survive part of distillative purification processes or can get into the stream to be hydrogenated in gas phase processes.

In fermentative processes for the production of succinic acid, for example, the acid produced is not only succinic acid, but also a number of other acids such as formic acid, acetic acid, propionic acid and butyric acid. These are due to their acidity in a position to damage catalysts.

The object of the present invention is to provide a process for the preparation of succinic anhydride and highly pure succinic acid, starting from succinic acid prepared by fermentation, which avoids the disadvantages of known processes and gives the desired products in high yield and purity. A hydrogenation catalyst used in a possible subsequent hydrogenation step should have a long service life. In addition, the process should be carried out as inexpensively as possible. The object is achieved by a process for the preparation of succinic anhydride, comprising the steps a) fermentative production of succinic acid, b) conversion of succinic acid from step a) with elimination of water and water separation in succinic anhydride, c) conversion of the succinic anhydride from step b) into the gas phase , d) removing sulfur-containing compounds from the succinic anhydride by passing the succinic anhydride from step c) over a guard bed which absorbs the sulfur-containing compounds e) absorbing the purified succinic anhydride in a solvent or condensing the succinic anhydride as a melt or as a solid and by a process for the production of highly pure succinic acid comprising the steps a) to e) as described above, furthermore after step e) the following step f) comprising f) conversion of the succinic anhydride from step d) o the e) with water to succinic acid, with an alcohol to succinic acid esters or with an amine to succinic acid amides.

It has been found according to the invention that, in the production of succinic anhydride and highly pure succinic acid starting from fermentatively produced succinic acid, for. B. the hydrogenation to tetrahydrofuran, 1, 4-butanediol and / or gamma butyrolactone or via the hydrogenation to 1, 4-butanediol the preparation of polyesters or polyurethanes or by esterification with diols, the production of Polybernsteinsäureester and by reaction with amines the formation of Polyamides can be carried out with a high catalyst life, when succinic acid prepared by fermentation is purified over the succinic anhydride, and sulphurous compounds are removed from the succinic anhydride using a guard bed.

In addition to sulfur-containing compounds, other interfering compounds which contain P, As, Sb, Bi, Sn or halogens such as Cl, Br or I are preferably also absorbed by the protective bed so that they do not enter the stream to be hydrogenated which reacts with the hydrogenation catalyst will be contacted. Step a)

Fermentation in biology is a form of enzymatic conversion of organic matter. The fermentation is used in many biotechnological production processes. This is done, for example, by adding the required enzymes or by adding bacterial, fungal or other biological cell cultures that carry out the fermentation as part of their enzyme-catalyzed metabolism.

The fermentation broth preferably contains enzymes, bacteria, fungi and / or other biological cell cultures. In addition, the fermentation broth contains biomass.

By biomass are meant, for example, substances that occur either directly in nature, such as starch, cellulose or sugar, or derived therefrom, such as glycerol and sugars formed by cleavage, such as glucose, sucrose, etc., as well as CO2. In this connection, reference is made to WO 2010/092155 A1 and the raw material sources mentioned therein. The preferred preparation of succinic acid is via fermentation.

The required microorganisms may already be present on the starting materials. Preferably, however, pure culture cell cultures are added to the fermentation process according to the invention in order to better control the fermentation and to exclude undesired by-products. Therefore, the sterile operation of the reactor is important.

The main field of application of fermentation is biotechnology for the production of various fermentation products such as bioethanol, amino acids, organic acids such as lactic acid, citric acid and acetic acid, enzymes such as phytase, antibiotics and other pharmaceutical products, biomonomers and biopolymers.

For a detailed description of the fermentation can be found on WO 2009/024294 and

WO 2010/092155 be referenced. The reactors according to the invention can replace stirred fermenters as well as bubble columns. Fermentation processes are generally in Chmiel; Bioprocess Technology: Introduction to Bioprocess Engineering, Volume 1, as well as in Chmiel, Hammes and Bailey; Biochemical Engineering. It may be batch, fed batch, repeated fed batch or continuous fermentation with or without biomass recirculation. This is often used to increase the yield with air, oxygen, carbon monoxide, carbon dioxide, ammonia, methane, hydrogen, nitrogen or suitable gas mixtures.

The fermentation broth may also be pretreated, for example, the biomass may be removed from the fermentation broth. For example, methods such as filtration, sedimentation and flotation can be used. The biomass can be removed by centrifuging, separators, decanters, filters or de-flotation devices. In addition, the biomass can be washed, for example in the form of a diafiltration, to remove the product maximize yield. The fermentation broth can also be concentrated, for example by evaporation under suitable conditions. Suitable evaporators are known.

The fermentation can be used according to the invention in particular for the preparation of succinic acid or salts or derivatives thereof. Suitable methods are described for example in WO 2010/092155 on pages 17 to 19 and in the examples.

After the fermentation, z. B. according to WO 2010/092155 A1, generally carried out the separation of the biomass from the product, for example by filtration. In the process, solids, in particular cells, are separated off. The product of the fermentation may be succinic acid directly, but at present the highest yields are achieved when the succinic acid is recovered as a salt so that the fermentation can proceed in a pH range between 6 and 8. These salts are, for example, mono- and disalts of succinic acid with ammonia or amines, as well as the alkali or alkaline earth metals. There are also mixtures possible. From these salts, the succinic acid is obtainable by acidification. This can be done, for example, with the aid of acidic ion exchangers, which are then regenerated in general with mineral acids such as hydrochloric or sulfuric acid, or by acidification with acids such as formic acid, hydrochloric acid, sulfuric acid, carbonic acid or phosphoric acid. Also possible is the so-called electrodialysis, in which by means of stream and membranes, aqueous succinic acid solution and, depending on the counterion of succinic acid, e.g. Alkali or alkaline earth hydroxides are formed, which can be recycled to the fermentation.

Depending on the impurities obtained in the preparation process and the work-up for the purified succinic acid, these compounds containing P, S, As, Sb, Bi, Sn or halogens such as Cl, Br and I can exhibit.

Since the fermentation is carried out in water, succinic acid or its salts is usually obtained as aqueous solutions. The acidification of the salts to obtain free succinic acid is usually also an aqueous process to obtain aqueous succinic acid solutions containing generally 1 to 15 wt .-% succinic acid, which may need to be tempered depending on the concentration, so that succinic acid does not precipitate if you do not want this.

It is also possible, before the acidification of the salts, to concentrate the solutions by removing water, for example by distilling off or by pervaporation. Subsequently, the usually warm salt solution with a content of, for example, 10 to 60 wt .-% succinic acid salt at temperatures of 20 - 100 ° C are acidified. Then it can be cooled down so that the succinic acid precipitates. The crystallized succinic acid is then filtered from the aqueous salt solution, for example Na or Mg salts of hydrochloric or sulfuric acid.

A first crystallizate of succinic acid can be further dissolved in water for further purification, but with losses of product by discharges, and again dissolved in water be crystallized. This can be done until the succinic acid has been purified to the desired specification, but the yield decreases with each crystallization step. In the method according to the invention is preferably crystallized a maximum of two times, more preferably at most one time. This is also because crystallizations not only reduce the yield, but also the investment for this are considerable.

The succinic acid prepared in this way generally contains the following impurities, the amount of impurities decreasing with the number of purification steps, followed by acidifying with HCl and calculating the percentages by wt refer to each element.

Crystals after 1. crystallization:

Total of halogen calculated as chlorine 0.01 to 2%

Sulfur 0.001 to 0.1%

Nitrogen 0.001 to 0.1%

Phosphorus 0.01 to 100 ppm

Arsenic, antimony, bismuth, tin in total 0.01 to 20 ppm

Magnesium 0.1 to 1000 ppm

Iron, manganese, chromium, molybdenum in total from 0.1 to 100 ppm

Calcium 0.1 to 100 ppm

Sodium, potassium in total from 0.1 to 100 ppm

Crystals after 2nd crystallization:

Total of halogen calculated as chlorine 0.01 to 20 ppm

Sulfur 0.01 to 10 ppm

Nitrogen 0.01 to 10 ppm

Phosphorus 0.01 to 3 ppm

Arsenic, antimony, bismuth, tin in total 0.01 to 3 ppm

Magnesium 0.01 to 3 ppm

Iron, manganese, chromium, molybdenum in total 0.01 to 3 ppm

Calcium 0.01 to 3 ppm

Sodium, potassium in total 0.01 to 3 ppm

According to the invention, the sulfur content, based on succinic acid, at the end of step a) is preferably in the range from 0.001 to 0.1% by weight or 0.01 to 10 ppm.

Preferably, in step a) succinic acid is produced by fermentation from at least one carbon source and, after separation of the biomass from the fermentation broth, is converted by acidification into the acid form. Particularly preferably, the succinic acid thus prepared is converted without further / additional purification steps in step b).

Unless indicated otherwise, the temperature data given in the following steps refer to the bottoms of the respective evaporation or distillation. specified Unless otherwise stated, pressures refer to the top of the distillation (top pressure). Simple evaporation is the pressure in the evaporation stage.

The terms used in this invention "high boilers" and "low boilers" describe over the respective reference product higher or lower boiling compounds, for example succinic or succinic higher or lower boiling compounds, the corresponding evaporation at the same pressure at lower or higher temperature / boiling. Step b)

In the process according to the invention, succinic acid is now introduced into the inventive step b) as an aqueous solution or as a melt which may still contain water. Depending on the water content, solution water can be removed in a first step, in which case the conversion of succinic acid into the anhydride can already take place, whereby in turn water is liberated, which is then separated off in this step. A succinic acid solution having a concentration of 5-50% by weight is preferably introduced into one or more evaporation devices connected in series or in parallel, preferably at 100 to 250 ° C. (temperature measured in the bottom) and preferably at pressures of 50 to 1000 mbar absolutely distilled off water. Preferably 150 to 220 ° C, more preferably 150 to 200 ° C at preferred pressures of 0.1 to 0.5 bar absolute, more preferably 0.15 to 0.3 bar absolute. For optimal energy utilization, the evaporation devices, possibly with other system units, be coupled in a heat network. On the evaporation apparatus, a column can be placed, which avoids the loss of succinic acid or anhydride by reflux. For example, the evaporator device may be a simple kettle that can be agitated and / or recirculated. Also possible is a falling film, thin film, natural circulation, forced circulation or spiral tube evaporator. The bottom product in which already formed succinic anhydride is and which has a water content of preferably 0.01 to 30% by weight, preferably 0.05 to 15% by weight, particularly preferably 0.1 to 10% by weight, can now as such are transferred to step c), or it can be further reacted and concentrated in a further distillation unit.

Step c)

In step c), the succinic anhydride from step b) is converted into the gas phase.

Preferably, step c) can be carried out in at least one distillation apparatus at a top pressure in the range of 0.02 to 2 bar and a bottom temperature in the range of 100 to 300 ° C with removal of high boilers via the bottom. Preferably, in this embodiment, step c) is carried out at a lower pressure than step b), and in step c) water and optionally low boilers are removed overhead, and gaseous succinic anhydride is recovered via a side draw. Alternatively, step b) and step c) can be combined and in at least one distillation apparatus at a top pressure in the range of 0.02 to 2 bar and a bottom temperature in the range of 100 to 300 ° C with removal of high boilers via the bottom, separation of water over Head and recovery of gaseous succinic anhydride are carried out via a side draw. The individual process alternatives are explained in more detail below.

Together with the water, harmful carboxylic acids such as v. A. Removed formic acid and acetic acid, so that they can not damage this later by corrosion on the catalyst.

In this further (or more in series or in parallel) distillation unit succinic anhydride, which may still contain succinic acid, further purified or prepared. Crucial here is that succinic anhydride is brought into the gas phase, so that it can be preferably separated from high-boiling impurities. So that the cleaning effect is as high as possible, the distillation is preferably operated with reflux. Preferably, the reflux, based on the added amount of succinic / succinic anhydride, is between 0.1 and 10 units, more preferably 0.2 to 5 units. The high boilers are discharged via swamp.

In this variant, there are three preferred process variants: According to one variant, the high boilers of gaseous succinic anhydride are separated at 100 to 300 ° C., preferably 150 to 270 ° C., more preferably 170 to 250 ° C. (bottom temperatures) and

(Head) pressures from 0.02 to 2 bar absolute, preferably from 0.03 to 1 bar and particularly preferably from 0.04 to 0.5 bar. The produced succinic anhydride is discharged from the distillation apparatus. It is then converted into the stage d) according to the invention. It is also possible, in a combination of steps c) to e) according to the invention, to incorporate the condensed succinic anhydride into an inert solvent which does not interfere with or alter the succinic anhydride in the subsequent step, or to collect the anhydride as a melt and the dissolved or melted succinic anhydride to drive fluidly over the protection bed. Here, the separation of the high boilers of gaseous succinic anhydride at 100 to 300 ° C, preferably 150 to 270 ° C, more preferably 170 to 250 ° C (bottom temperatures) and (head) pressures of 0.02 to 2 bar absolute, preferably from 0.03 to 1 bar, and more preferably from 0.04 to 0.5 bar. Subsequently, succinic anhydride can be taken up in an inert solvent. This can be done in apparatus known to those skilled in the art. These include, for example, absorption columns in counter, cross or direct current, bubble columns, jet nozzle reactors,

Loop reactors, stirred tank reactors, etc. Subsequently, the liquid or dissolved succinic anhydride in the step d) according to the invention is transferred. According to the third variant, which comprises the interconnection / combination of steps c) to e) according to the invention, the evaporation of succinic anhydride in the presence of hydrogen, wherein a portion of the gaseous succinic anhydride condenses to produce the reflux. The remainder, together with the hydrogen, passes through the guard bed into the hydrogenation. This is generally at bottom temperatures of 150 to 300 ° C, preferably 160 to 270 ° C, more preferably 180 to 250 ° C at pressures (absolute) of 1 to 65 bar, preferably 2 to 30 bar, particularly preferably from 5 to 20 bar performed.

To increase the yield, the bottom stream containing succinic anhydride may be recycled wholly or at least partially to one or more preceding stages. However, especially in longer running processes for the production of technical product quantities, a discharge to avoid accumulation will be beneficial. Therefore, it is preferable to further work up this discharge stream in a further distillation device. Preference is given here to using a thin-film evaporator in which succinic anhydride distills off via the top, which is then recycled to one of the preceding stages. The high boiler stream is discharged. The evaporation is preferably 100 to 300 ° C, preferably 150 to 270 ° C, particularly preferably 180-250 ° C and pressures of preferably 1 to 200 mbar absolute, preferably between 3 and 100 mbar, more preferably at 5 to 50 mbar carried out.

In order to remove harmful, basic N-containing compounds in step c) according to the invention, preference is given to converting the basic compounds into high-boiling substances. These basic N-containing compounds may be, for example, ammonia, aliphatic amines, amino acids, etc. In order to prevent these go into the gas phase together with succinic anhydride, it is advantageous to convert them into high-boiling compounds. This can be done, for example, by working in the presence of an acid which, together with the basic compounds, forms high-boiling salts. These are, for example, salts of high-boiling carboxylic acids such as adipic acid, acidic amino acids, sulfonic acids such as dodecylbenzenesulfonic acid, methanesulfonic acid, mineral acids such as phosphoric acid, sulfuric acid or heteropolyacids such as tungstophosphoric acid. Preferably, 1 to 1, 5 mol equivalent of acid is added per equivalent of basic compound. Another preferred option, which may supplement the salt formation, is the chemical conversion of basic N-containing compounds into high-boiling compounds, for example the formation of amides. For this purpose, they are reacted, for example, to sulfonic acid or carboxylic acid ammonium salts at residence times of 0.1 to 2 hours and at temperatures of 150-300 ° C. This can take place, for example, in the swamps of the evaporation devices. Suitable reaction partners are, for example, sulfonic acids or carboxylic acids as described above. If basic N-containing components are not removed as far as possible before the hydrogenation, it may be expected that the acidic catalyst centers necessary for the production of THF are gradually neutralized, thereby reducing the yield of THF. Step d)

The inventive step d) is significantly responsible for ensuring that z. For example, a later process in which succinic acid or its anhydride is converted into derivatives thereof may be operated for a long time at high selectivity and high conversion. This is made possible by catalyst poisons, which form volatile compounds and could enter together with succinic anhydride in the hydrogenation and z. As the elements P, S, As, Sb, Bi, Sn or halogens such as Cl, Br and I, above all sulfur, on absorber, also referred to as a guard bed (guard bed), are added.

The absorber which is to absorb these catalyst poisons does not harm succinic anhydride if possible. The absorber can either serve only to remove the catalyst poisons or even catalytically convert the succinic anhydride into its desired products. Particularly preferred is a further catalytic derivatization of succinic anhydride, for example in a hydrogenation or esterification, the absorber and the subsequent catalyst to the same material, so that they can be used in a bed in a reactor.

The absorber preferably has the sharpest possible profile with a high absorption capacity with respect to the catalyst poisons. Here, sharp profile means that said catalyst poisons are absorbed in the guard bed in a spatially very narrow range and do not have a broad distribution over the length of the guard bed. This makes it possible to deliberately exchange used protection bed, with only small amounts of protective bed must be replaced. It is preferred that, measured at the behavior of the sulfur, upon reaching at least 90% of the absorption capacity under reaction conditions, after further 50 cm, preferably 40 cm, more preferably 30 cm along the gas path or protective bed only 10% sulfur has been taken. It should be noted that absorbers which, for example, contain sulfate as a result of their production process, can falsify the measurements. In this case, it is necessary to deduct the "zero value" of sulfur corresponding to the value caused by the sulfur in the feed.

Suitable absorbers for the removal of P, S, As, Sb, Bi, Sn and halogens such as Cl, Br and I, in particular sulfur, contain, for. Co, Ru, Re and Cu. Preference is given to Ru and Cu, more preferably Cu. It is advantageous if the content of metal, which can absorb the catalyst poisons, is as high as possible. Thus, the content of the absorber suitable for receiving the toxic constituents, measured as an element, is preferably greater than 10% with respect to the total weight of the catalyst, preferably> 25%, more preferably> 40%, but preferably not more than 90%, otherwise the surface capable of taking up becomes too small. The absorption capacity of sulfur is normalized to metal content preferably between 0.5 and 10 wt .-%, preferably between 1 and 10 wt .-%. The weight percentage of the metal in the total weight of the absorber (calculated as element) is preferably between 0.5 and 80%. In the case of Cu, the preferred proportion is between 10 and 80%, more preferably between 25 and 65%. The metals are preferably applied to a carrier system. Suitable carriers preferably have acidic sites and preferably contain oxides based on B, Al, Si, Ti, Zr, La, Ce, Cr, or carbon, for example in the form of activated carbon. Another carrier which is not oxidic is, for example, SiC. The production of the absorber is achieved, for example, by impregnating active metal precursors, for example Cu salt solutions, on the supports. Absorbers are also suitable in which the active components are precipitated onto a support or precipitated together with the support material from dissolved precursors thereof. After drying and optionally calcination of the absorber material, the absorber is preferably activated with hydrogen before the beginning of the reaction, if necessary, for example in a subsequent hydrogenation, the hydrogenation catalyst is activated with hydrogen. In a particular variant, in which absorbers and the subsequent catalyst are identical, the absorber is activated together with the catalyst.

Particularly preferred absorbers contain not only Cu but also aluminum oxide.

The heterogeneous absorbers are generally shaped articles having an average particle size greater than one millimeter. Strands, tablets, star strands, trilobes, hollow bodies, etc. are preferably used. The absorber for removing catalyst poisons is preferably arranged as a fixed

Layer e.g. used in a shaft or tube bundle reactor. Regardless of whether only one or more apparatuses are used, it is possible to work with as little absorber as possible to remove catalyst poisons, if these are removed from time to time and, if possible, replenished before they are fully loaded. This is useful if the process according to the invention, for example, due to maintenance work must be turned off anyway.

The reactors used for the desulfurization are types known to the person skilled in the art. Examples thereof are shaft reactors, tube bundle reactors, fluidized bed reactors, etc. It can be purified in a reactor and further reacted or arranged in several reactors in parallel or in succession, whereby several types can be combined.

In this way, a lifetime of a downstream catalyst of more than 6 months, preferably more than 1 year, can be achieved.

Between step c) and step d), the succinic anhydride can be condensed according to an embodiment of the invention and subsequently evaporated again. It can do that condensed succinic anhydride are also transferred in the meantime in the solid state.

The sulfur content, based on the succinic anhydride, after step d) is preferably <0.001 to 5 ppm by weight, more preferably 0.001 to 1 ppm by weight.

Equal values are preferably for compounds containing P, As, Sw, Bi, Sn or halogens such as Cl, Br or I. In a preferred variant, the succinic anhydride obtained can be fed together with hydrogen to a coupled purification and gas-phase hydrogenation with tetrahydrofuran, 1, 4-butanediol or gamma-butyrolactone as product. The molar ratio of hydrogen to succinic anhydride is preferably from 20 to 300 to 1, preferably from 30 to 250 to 1, particularly preferably from 50 to 200 to 1. The pressures (absolute) are preferably from 1 to 65 bar, preferably from 2 to 30 bar, particularly preferably from 5 to 20 bar. The temperatures are preferably 150 to 350 ° C, preferably 170 to 320 ° C, more preferably 200 to 300 ° C.

Steps)

The succinic anhydride can be condensed after step d) in a step e) as a melt or solid or recovered as a solution in a solvent.

The condensation in step e) may preferably be carried out at temperatures of 100 to 300 ° C, more preferably from 130 to 200 ° C. If an intermediate solidification of succinic acid is desired, it is also possible to work at a lower temperature. The absolute pressure is preferably 0.5 to 20 bar, more preferably 0.8 to 15 bar, in particular 1 to 10 bar. As a result of this process control, the succinic anhydride purified from the majority of the low and high boilers can subsequently be introduced into a gas phase process both as a melt or as a solution in a liquid phase process and as a gas stream. When adding a solvent to the condensed succinic anhydride, a solution of 0.1 to 50% by weight, preferably 0.5 to 40% by weight, more preferably 1 to 30% by weight, of succinic anhydride is prepared in each solvent. Should a gas phase reaction be sought in the subsequent step, the succinic anhydride already purified from light and high boilers can either be vaporized directly or converted into the gas phase in a stripping column with a carrier gas. Stripping with a carrier medium, the liquid succinic anhydride is transferred to a column in which at certain pressures and temperatures, the succinic anhydride is transferred into the gas phase. The molar ratio of the carrier medium to succinic anhydride is 20-300 to 1, preferably 30-250 to 1, particularly preferably 50-200 to 1 . The pressures (absolute) are between 1 to 65 bar, preferably 2 to 30 bar, more preferably 5 to 20 bar. The temperatures are 150 to 350 ° C, preferably 170 to 320 ° C, more preferably 200 to 300 ° C. The column can be different internals such. As fillers, sheet metal packings, fabric packaging or soil. If appropriate, it is also possible to separate off further impurities which have been evaporated in step b) according to the invention as high boilers with succinic acid.

In a preferred variant, the succinic anhydride is treated with a solvent boiling higher than succinic anhydride. Examples of this solvent, which should preferably be inert to succinic anhydride, are phthalates or terephthalates based on CA to C15 alcohols, for example dibutyl phthalate, corresponding to ring-hydrogenated phthalates or terephthalates, hydrocarbons, ethers based on ethylene oxide and / or propylene oxide and the like. Step f)

Step f) may be performed after step e) and comprises reacting the succinic anhydride from step e) with water to give succinic acid, an alcohol, e.g. For example, Ci-12-alkanol or fatty alcohol, the ester of succinic acid, wherein also polyols can be used to subsequently form a polyester, or a monofunctional amine, eg. B. C1-12 alkyamine, or polyamine to di- or polyamide, if a polyamine is used.

The amines or alcohols may be vegetable oil derivatives, i. H. to compounds derived from vegetable oil. The alcohols are preferably C-24-alcohols which may be branched, unbranched or cyclic. They can be saturated or unsaturated. They may be aliphatic, aromatic or bridged via aromatics aliphatic. It may be mono-, di- or polyols.

The amines may be equivalent compounds having amino groups instead of hydroxyl groups. Accordingly, it is also preferable to C1-24 mono-, di- or polyamines or polyetheramines.

Accordingly, in step f) after the production of succinic acid, these can be obtained by crystallization or separation of excess water.

In the reaction of succinic anhydride with water, for example succinic anhydride can be introduced into an aqueous phase. The concentration of succinic anhydride in the aqueous phase should preferably be chosen so that the final isolation can be carried out particularly efficiently, the reaction of the anhydride to the acid takes place as quickly as possible and no succinic acid precipitates as a solid during the reaction, except if desired. Subsequently, the succinic acid can be used as an aqueous solution, or you can remove the water so far that succinic acid can be obtained either by crystallization, or the water can be removed to dryness, but without raising the temperature so far that again dehydration to succinic anhydride. For example, succinic acid can be isolated as a solid.

In this way, succinic acid can be prepared with a purity of more than 99.9%, with any catalyst poisons, such as low and high boilers and sulfur-containing components, can be depleted to below 5 ppm, preferably below 1 ppm.

In a further preferred variant, in a combination of steps e) and f) according to the invention, the succinic anhydride can not be isolated after purification by the protective bed, but can be converted directly into the desired products by reaction with a reactant in one step. Examples include the reaction with a monovalent alcohol to diester of succinic acid, the reaction with a polyol to polyesters, a reaction with monovalent amines to diamide or a polyamine to the polyamide.

The invention is further illustrated by the following examples.

Example 1: Recovery of succinic anhydride (BSA)

A crude fermentation effluent obtained according to WO 2010/092155 A1, Example 6 was acidified to a pH of 3 after separation of the bio-mass by filtration with HCl. This mixture was pumped continuously into a recirculating residence tank with attached column. At about 4 hours average residence time then water was distilled off at 200 mbar and 180 ° C bottom temperature. The liquid, about 180 ° C hot bottom containing high boilers, BSA and below 5% free succinic acid was continuously introduced into a column with side draw in the rectifying section and at a top pressure of 50 mbar and bottom temperatures of about 180 ° C. distilled. Essentially water was removed overhead which contained 2 ppm by weight of N, and BSA was discharged via the side draw and the high boilers were discharged via the bottom. The high boilers contained 0.03% by weight of N, 0.02% by weight of S. In this way, BSA could be obtained in about 97% yield based on succinic acid in the fermentation effluent. The BSA had a sulfur content of 5 ppm by weight.

Example 2a: Hydrogenations

The apparatus used in the examples consisted of a companion-heated inlet part with storage vessel and pump, an evaporator filled with glass rings, a 3 m long tube reactor with 2.7 cm inner diameter and external Doppelmantelölbeheizung or cooling and internal thermocouple tube, a water-cooled first separator, a second cooled to 6 ° C separator and a circulating gas blower and fresh gas and exhaust facilities. To evaporate succinic anhydride, the succinic anhydride (BSA), the recycle gas and the fresh hydrogen were passed into the evaporator. The molar ratio of fresh hydrogen to BSA was 2.1 to 1, with the excess gas being discharged as exhaust gas. The molar ratio of cycle gas to BSA was about 100 to 1.

Comparative Example 2b

The reactor was charged with 1 liter of a CuO (50 wt%) / Al 2 O 3 catalyst (2.5 mm strands). Above the catalyst, 100 ml of glass beads were filled as inert bed. After inerting with nitrogen, the catalyst was activated with a nitrogen / hydrogen mixture at atmospheric pressure (the gas stream is adjusted to 99.5% nitrogen and 0.5% hydrogen, then the reactor is heated to 130 ° C.) After 2 hours, the reactor each temperature setting is held for 30 minutes, after reaching 180 ° C, the hydrogen content is increased to 1%, after one hour to 5% again for one hour, then the hydrogen content on 100% raised). After activation of the catalyst, the cycle gas blower is put into operation and the pressure in the reactor to 9 bar absolute and the reactor temperature is set to 230 ° C. Subsequently, the BSA feed was started up in the reactor. There were continuously promoted 100 g of BSA h. Thereafter, the temperature in the first third of the reactor increased to up to 245 ° C, then dropped to almost Ölbeheizungs / cooling level (about 230 ° C), then in the last third of the catalyst bed again rise up to 235 ° C and briefly before the end of the catalyst bed again fall to almost 230 ° C.

The liquid effluents from the separators were collected and pooled and analyzed by gas chromatography (GC area percent). It found 98.3% THF and 1, 5% n-butanol. The remainder consisted of several compounds, not more than 0.05% as a single component, such as n-butyraldehyde, dibutyl ether and gamma-butyrolactone.

After a running time of 1000 h, the temperature profile in the reactor had changed so that the places of the highest temperatures had moved slightly backwards and the reaction temperature at the end of the reactor at about 232 ° C, so no longer reached the Ölbeheizungs / cooling level , The hydrogenation effluent contained 95.1% THF, 1.8% n-butanol, 2.8% gamma-butyrolactone, 0.1% BSA, and below 0.05% each, e.g. n-butyraldehyde, butyric acid, dibutyl ether and methyl butyl ether.

A short time later, the plant had to be shut down, as probably threatened by plaque from BSA, the separator to clog. Example 2b according to the invention:

Comparative Example 2 was repeated with the difference that above the one liter of catalyst instead of 100 ml of glass beads in this order 10 ml glass beads, 50 ml CuO (60 wt .-%) / Al203 3 mm tablets, and 40 ml glass beads were filled. The glass spheres between the two Cu catalysts served to make it easier to remove separately for the purpose of analysis. The filling height of the 50 ml catalyst was about 10 cm taking into account the internal diameter of the reactor and the inner tube with the thermocouples.

After a trial period of 2,000 hours, the experiment was terminated without material changes having been made to the temperature profiles or the discharge composition. Thus found in the discharge 98.2% THF, 1, 6% n-butanol. The remainder consisted of several compounds, as a single component not exceeding 0.05%, such as n-butyraldehyde, dibutyl ether and gamma-butyrolactone.

The product is purified by distillation in three columns, the first column essentially discharging water, butanol and gamma-butyrolactone via the bottom, the second column, which is operated at a higher pressure than the first column, overhead. distilled off ser / THF azeotrope, which is recycled to the first column, and the bottom gives anhydrous THF, which is essentially freed of butyraldehyde (bottom product) in a third column. The resulting THF has a purity of> 99.9% and can be used as such, for example, for the production of polyTHF. It contains less than 1 ppm by weight N.

The 50 ml Cu catalyst tablets were removed under nitrogen blanket in 5 equal fractions and analyzed for their sulfur content. Compared to a sulfur content of 0.01% by weight in the unused catalyst, the sulfur contents in the first two layers were 1, 5 and 0.3% by weight, in the third layer 0.1% and in the fourth. And 5th layer at about 0.02%. Under the reaction conditions, the maximum absorption capacity of the sulfur is therefore at least 1, 5 wt .-%.

Example 3 (Comparative Example)

The succinic anhydride from Example 1 was hydrogenated as a 20% strength by weight aqueous solution on a Re / Pt / C catalyst analogously to Example 1 DE10009817 A1 (feed 100 g / h, temperature 155 ° C., pressure 220 bar, 20 mol of hydrogen / h, 120 ml of catalyst, tubular reactor, 2 cm diameter, trickle-bed procedure Initially the 1,4-butanediol yield was about 95% at 100% conversion (remainder butanol, propanol, THF and gamma-butyrolactone) Sales to 98% and the butanediol yield was only 90%. Example 4 (according to the invention):

Example 3 was repeated, with the difference that 50 g / h succinic anhydride at 125 ° C over 100 ml of the catalyst (CuO (60 wt .-%) / Al ₂ 0 ₃ 3 mm tablets) from Example 2b at 1, 5 bar Overpressure and 5 standard liters of hydrogen / h were conducted in the upflow mode (tubular reactor, oil-heated, 2 cm diameter). The effluent was collected, dissolved in water according to Example 3 and hydrogenated. The hydrogenation result was also after 100 h as at the beginning (98% Butandiolausbeute, 100% conversion).

Claims

claims

1 . Process for the preparation of succinic anhydride, comprising the steps a) fermentative production of succinic acid, b) conversion of succinic acid from step a) with elimination of water and water separation in succinic anhydride, c) conversion of the succinic anhydride from step b) into the gas phase, d) removal of sulfur-containing Compounds of the succinic anhydride by passing the succinic anhydride from step c) through a solid guard bed which absorbs the sulfur-containing compounds. e) absorption of the purified succinic anhydride in a solvent or condensation of the succinic anhydride as a melt or as a solid.

2. The method according to claim 1, characterized in that in step a) succinic acid is produced by fermentation from at least one carbon source and transferred after separation of the biomass from the fermentation broth by acidification in the acid form.

3. The method according to claim 2, characterized in that the succinic acid from step a) without further purification steps in step b) is transferred.

4. The method according to any one of claims 1 to 3, characterized in that the dehydration and removal of water takes place in at least one evaporation device at a pressure in the range of 0.05 to 1 bar and a sump temperature in the range of 100 to 250 ° C.

5. The method according to any one of claims 1 to 4, characterized in that step c) in at least one distillation apparatus at a top pressure in the range of 0.02 to 2 bar and a bottom temperature in the range of 100 to 300 ° C with removal of high boilers over the sump is carried out.

6. The method according to claim 5, characterized in that step c) at lower

Pressure as step b) is carried out and in step c) water and optionally low boilers are separated overhead and gaseous succinic anhydride is obtained via a side draw.

7. The method according to any one of claims 1 to 3, characterized in that step b) and step c) summarized and in at least one distillation apparatus at a top pressure in the range of 0.02 to 2 bar and a bottom temperature in the range of 100 to 300 ° C with removal of high boilers via the bottom, removal of water overhead and recovery of gaseous succinic anhydride via a side draw.

8. The method according to any one of claims 1 to 7, characterized in that the solid protective bed in step d) contains a sulfur-binding metal selected from Ru, Re, Co, Cu and mixtures thereof.

A method according to claim 8, characterized in that the protective bed in step d) is an absorber in which the sulfur-binding metal is present on a carrier material which is selected from carbon and / or at least one oxide of B, Al, Si, Ti, Zr, La, Ce and / or Cr.

10. A process for the preparation of highly pure succinic acid, succinic esters or

Succinic amides comprising the steps a) to e) according to any one of claims 1 9, further after step e) the following step f) comprising f) reacting the succinic anhydride from step d) or e) with water to succinic acid, with an alcohol to succinic acid esters or with an amine to succinic amides.

1 1. A method according to claim 10, characterized in that in step f) after the production of succinic acid, this is obtained by crystallization or separation of excess water.