DE102007058991A1 - The use of low-chloride, low-carbonate silica sand as retention material for solid acid catalysts, especially in solid-bed reactors for condensation reactions, preferably for production of Bisphenol A - Google Patents

Abstract

The use of low-chloride, low-carbonate silica sand (I) as retention medium for catalysts based on solid acids in solid bed reactors. An independent claim is included for a method for the production of Bisphenol A from phenol and acetone in downward-flow solid bed reactors containing acid ion exchange resins (II) as catalysts, in which (I) is used as retention medium for (II).

Description

The The present invention relates to the use of low in chloride and carbon atoms Quartz as a retention medium for catalysts Base of solid acids in fixed bed reactors. The present Invention is particularly suitable for use in the production of bis (4-hydroxyaryl) alkanes, more preferably for the production of bisphenol A.

Methods for the synthesis of bisphenol A (BPA) by ion exchange catalysis are e.g. In US Pat. No. 4,391,997 . US-A 4,400,555 . US-A 4 590 303 or EP-A 210 366 described. It is known, for the industrial production of BPA, to pass a mixture of phenol and acetone through a fixed bed reactor filled with sulfonic acid ion exchange resins based on polystyrene and then to feed it to the workup. It is also known to use fixed bed reactors through which the product stream can be passed either top to bottom (downflow) or bottom to top (upflow) through the reactor. Both directions of flow have advantages and disadvantages.

In the upward flow as in US 2004/0068085 A1 described is advantageous that the total pressure load of the catalyst, ie the sum of hydrostatic and hydrodynamic pressure over the catalyst bed, at the same flow rate is lower than in the downward flow. However, the catalyst, which is used in the form of polymer beads of about 0.3-1 mm in diameter, be discharged at high flow rates with the reaction solution from the reactor. This is possible in particular when using small ball diameters or when forming fine catalyst abrasion. Catalyst, which passes through such discharge in the work-up of the reaction solution and the product purification, there leads to decomposition reactions of bisphenol A and thus deteriorates the product quality. When driving in upward flow therefore mechanical restraints z. B. metallic sieve trays used above the catalyst bed to prevent strike-through, ie discharge, of the catalyst. Another disadvantage of the upward flow is the risk of channeling, which worsens the utilization of the fixed catalyst bed.

If the fixed bed reactor is operated in the downward flow of the reaction medium, differential pressure builds up over the catalyst bed. This is inter alia dependent on the flow rate of the reaction medium, the grain size of the catalyst and the degree of crosslinking of the ion exchanger (see. DE 197 57 570 A1 ). The total pressure with which the catalyst is loaded, must be particularly observed in order not to damage the catalyst bed sustainably. The discharge of catalyst from the reactor can also - as in US 2004/0068085 A1 described - be prevented by a metal sieve on the reactor bottom.

These Type of catalyst retention has the disadvantage that it during operation to a complete or partial Clogging of the sieve bottom by catalyst abrasion or catalyst fragments can come. Such blockages can either complete the Standstill of the operation or an increase the pressure loss and possibly additionally unevenly distributed Cause flow in the reactor. All these effects are disadvantageous for the operation, since they are for. B. the throughput through the reactor and thus limit the production volume.

In DE 197 57 570 A1 is further described that a gravel / sand layer is used in the lower part of the reactor as the carrier of the ion exchange bed.

In EP 1 480 993 B1 The use of poured restraints is also described. Possible materials described are silica-based sand, silica-based gravel and ceramic bodies.

The Previously described gravel / sand layers as retaining devices have the disadvantage, however, that they, especially acidic media, are not completely inert and therefore in the medium term by the Throughput of these media are washed out, causing instability can lead to such layers. In particular, you can also corrosive components for the following system components be washed out.

It Therefore, there was still a need for suitable restraint devices for solid, acid catalysts in fixed bed reactors, the preferably be operated in downflow, which do not show the aforementioned disadvantages.

The Object of the present invention was therefore to provide a suitable technical solution for catalyst retention in fixed-bed reactors filled with acidic catalyst without causing corrosion in connected system parts the restraint is caused. Continue to exist the desire for long-term stability of such catalyst retention.

It has now surprisingly been found that the use of low-chloride and low-carbonate quartz sand as a retention medium for acidic catalysts, preferably acidic ion exchangers, in one preferably from top to bottom flowed through fixed bed reactor is particularly suitable. This is especially the case with the use of acidic medium.

object The present invention therefore provides the use of chloride and low carbon quartz sand as a retention medium for Catalysts based on solid acids - below also referred to as acid catalysts for short - in fixed bed reactors.

Under the corresponding reaction conditions in with acidic catalyst filled fixed bed reactors can pass through the reaction medium in conventional sand or gravel contained chloride ions be dissolved out of the sand or gravel bed and in the following parts of the system lead to corrosion. Farther can under the appropriate reaction conditions in by acid catalyst filled fixed bed reactors the reaction medium contained in conventional sand or gravel carbonate ions be dissolved out of the sand or gravel bed, resulting in Bed decomposition, catalyst breakthrough and disturbance of the operation can lead. These disadvantages are caused by the use of low-chloride and low-carbonate quartz sand significantly reduced or completely avoided. This will both the service life and thus the service life of the downstream system components as well as the life of the sand bed as a retention device and thus the cycle between the renewal of this sand bed necessary shutdowns of the reactor considerably extended.

For the purposes of the invention, catalysts based on solid acids are those having a pK _a value of less than 4, preferably less than 2, particularly preferably less than 1. Examples of such acidic catalysts are preferably acidic ion exchange resins, aluminosilicates in H form, in the context of the invention the corresponding reaction conditions, solid Lewis acids or other heteropolyacids. Particularly preferred are acidic ion exchange resins.

Acid ion exchange resins may include, for example, polycondensates, e.g. B. available from phenol and formaldehyde, or polymers, eg. B. obtainable by copolymerization of styrene, acrylates or methacrylates and divinylbenzene. However, it is also possible to use other correspondingly functionalized macromolecules, for example those of natural origin, such as celluloses, dextrans and agaroses. As acidic groups, such ion exchange resins may have functional acidic groups such as, for example, phenolic hydroxyl groups, carboxyl groups and / or sulfonic acid groups. The acidic groups can be introduced into the polycondensates or polymers either via the copolycondensation or copolymerization with monomers carrying such groups or after the polycondensation or polymerization has taken place. Depending on the type and combination of functional groups, the ion exchangers may vary in their acidity. For example, strongly acidic ion exchangers usually contain sulfonic acid groups, while weakly acidic ion exchangers often carry the less acidic carboxyl groups. However, any mixed forms are known between strong and weakly acidic ion exchangers. Examples of acidic group-containing ion exchangers are crosslinked, sulfonated polymers of styrene and divinylbenzene as described, for. B. under the trade name Lewatit ^® are sold.

Examples of fixed bed reactors are known in the art and z. In DE-A 197 57 570 or US-A 2004/0068085 described.

in the Frame of the invention is under quartz sand such with a middle Grain size from 0.3 to 80 mm, preferably from 0.5 to understand 70 mm. Also, quartz sand are within the scope of the invention Mixtures or bedding of several quartz sands with different mean particle sizes of 0.3 to 80 mm, preferably from 0.5 to 70 mm to understand.

According to the invention using quartz sands are commercially available or For example, they can be made from conventional chloride and carbonate-rich quartz sand by one to several hours Boil with strong mineral acids, such as. B. concentrated Hydrochloric acid, followed by one to several times Wash with hot water and then dry above of the boiling point of water. Cooking with strong Mineraic acids can preferably be between 1 and 10 Hours. Subsequently, preferably one to 4 sometimes with hot water, preferably with such between 30 and 80 ° C are washed, with particular preference deionized water is used during the last wash. The drying can be above 100 ° C at atmospheric pressure or at lower temperatures under reduced pressure.

Of the low-chloride and low-carbonate used in the invention Quartz sand preferably has a chloride content of less than 1000 Ppm by weight, preferably less than 200 ppm by weight, more preferably less than 50 ppm by weight and less than 5000 ppm by weight, preferably less than 2000 ppm by weight, more preferably less than 1000 ppm by weight, based in each case on the total weight of the quartz sand, on.

The chloride used in the invention and low-carbonate quartz sand may additionally have a sulphate content of less than 3000 ppm by weight, preferably less than 1000 ppm by weight, more preferably less than 300 ppm by weight, an iron content of less than 10000 ppm by weight, preferably less than 5000 ppm by weight "has a potassium content of less than 3000 ppm by weight, preferably less than 1000 ppm by weight, more preferably less than 500 ppm by weight, a calcium content of less than 3000 ppm by weight, preferably less than 1000 ppm by weight, more preferably less than 500 ppm by weight and / or a magnesium content of less than 3000 ppm by weight, preferably less than 1000 ppm by weight, more preferably less than 500 ppm by weight.

Prefers is the reaction medium flowing through the fixed bed reactors an acidic medium. Under acidic medium is within the scope of the invention one with a pH of less than 7 to understand. there is the acid that adjusts the pH, preferably around the acidic catalyst. The resulting pH is concentration-dependent. The concentration of acid is preferably at 0.01 to 2 ppm, more preferably at 0.1 to 1 ppm. The reaction medium may be in preferred embodiments aqueous-alcoholic solutions or solutions act aromatic alcohols. If within the scope of the invention Fixed bed reactor condensation reactions, particularly preferred for the preparation of bis (4-hydroxyaryl) alkanes carried out are, it is the reaction medium is preferably solutions in which reactants and products are dissolved. Preferably it is in a preferred embodiment for Preparation of 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) um a phenolic solution in which reactants and products are solved.

1 schematically shows the stratification in the inventive use of low-chloride and low-carbon quartz sand as a retention medium within a flow-through from top to bottom fixed bed reactor.

In the fixed bed reactor ( 5 ) from above the reaction medium containing the starting materials ( 1 ). This reaction medium flows through the fixed bed reactor ( 5 ) from top to bottom and is at the lower part as the medium containing products ( 4 ) discharged again from the reactor. The fixed bed reactor has in the lower part a perforated metal structure ( 3a ), such. B. a metal mesh, overlying sand bed ( 3 ) of low-chloride and low-carbon quartz sand as a retention medium for the acidic catalyst present in the layer ( 2 ) (Catalyst bed). The sand bed prevents 3 ) that catalyst from the catalyst bed ( 2 ) is discharged with the medium containing the products from the reactor.

The use according to the invention of the low-chloride and low-carbonate Quartz sand as a retention medium is preferably carried out in fixed bed reactors for Condensation reactions, particularly preferred for the preparation of bis (4-hydroxyaryl) alkanes, very particularly preferably the preparation of 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

worin
R^A für einen linearen oder verzweigten C₁-C₁₈-Alkylenrest, bevorzugt C₁-C₆-Alkylenrest, oder einen C₅-C₁₈-Cycloalkylenrest, bevorzugt einen C₅-C₁₂-Cycloalkylenrest steht,
R unabhängig voneinander für einen linearen oder verzweigten C₁-C₁₈-Alkylrest, bevorzugt C₁-C₆-Alkylrest, einen C₅-C₁₈-Cycloalkylrest, bevorzugt einen C₅-C₁₂-Cycloalkylrest, einen C₆-C₂₄-Arylrest, bevorzugt einen C₆-C₁₂-Arylrest, oder einen Halogenrest stehen und
x und y unabhängig voneinander für 0 oder eine ganze Zahl von 1 bis 4, bevorzugt unabhängig voneinander für 0, 1 oder 2 stehen.Suitable bis (4-hydroxyaryl) alkanes, which are obtainable as a retention medium using the low-chloride and low-carbonate quartz sand, are, for example, those of the general formula (I)

wherein
R ^{A is} a linear or branched C ₁ -C ₁₈ -alkylene radical, preferably C ₁ -C ₆ -alkylene radical, or a C ₅ -C ₁₈ -cycloalkylene radical, preferably a C ₅ -C ₁₂ -cycloalkylene radical,
R independently of one another are a linear or branched C ₁ -C ₁₈ -alkyl radical, preferably C ₁ -C ₆ -alkyl radical, a C ₅ -C ₁₈ -cycloalkyl radical, preferably a C ₅ -C ₁₂ -cycloalkyl radical, a C ₆ -C ₂₄ -Arylrest, preferably a C ₆ -C ₁₂ aryl radical, or a halogen radical and stand
x and y are independently 0 or an integer from 1 to 4, preferably independently 0, 1 or 2.

preferred Bis (4-hydroxyaryl) alkanes are 2,2-bis (4-hydroxyphenyl) propane (bisphenol A (BPA)), 2,4-bis- (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (3-methyl-4-hydroxyphenyl) -propane, bis- (3,5-dimethyl-4 -hydroxyphenyl) -methane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, 2,4-bis (3,5-dimethyl-4-hydroxyphenyl) -2-methylbutane, 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (Bisphenol TMC).

Especially Preferred bis (4-hydroxyaryl) alkanes are 2,2-bis (4-hydroxyphenyl) propane (Bisphenol A (BPA)), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) -propane, 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (Bisphenol TMC).

All Particularly preferred is 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

Bis (4-hydroxyaryl) alkanes are obtainable by methods known to those skilled in the art by Um Substitution of aromatic mono-hydroxy compounds which are not substituted in the p-position, with ketones having at least one aliphatic group on the carbonyl function, in a condensation reaction. An adduct of bis (4-hydroxyaryl) alkane and the aromatic monohydroxy compound used as starting material is preferably obtained as intermediate, which is subsequently separated into the desired bis (4-hydroxyaryl) alkane and aromatic monohydroxy compound.

die in p-Position nicht substituiert sind und worin,
R unabhängig voneinander für einen linearen oder verzweigten C₁-C₁₈-Allylrest, bevorzugt C₁-C₆-Alkylrest, einen C₅-C₁₈-Cycloalkylrest, bevorzugt einen C₅-C₁₂-Cycloalkylrest, einen C₆-C₂₄-Arylrest, bevorzugt einen C₆-C₁₂-Arylrest, oder einen Halogenrest stehen und
x oder y für 0 oder eine ganze Zahl von 1 bis 4, bevorzugt für 0, 1 oder 2 stehen.Suitable aromatic monohydroxy compounds are, for example, those of the general formula (II)

which are unsubstituted in the p-position and in which
R independently of one another are a linear or branched C ₁ -C ₁₈ -allyl radical, preferably C ₁ -C ₆ -alkyl radical, a C ₅ -C ₁₈ -cycloalkyl radical, preferably a C ₅ -C ₁₂ -cycloalkyl radical, a C ₆ -C ₂₄ -Arylrest, preferably a C ₆ -C ₁₂ aryl radical, or a halogen radical and stand
x or y are 0 or an integer from 1 to 4, preferably 0, 1 or 2.

Examples for suitable aromatic mono-hydroxy compounds of general formula (II) are, for example, phenol, o- and m-cresol, 2,6-dimethylphenol, o-tert-butylphenol, 2-methyl-6-tert-butylphenol, o-cyclohexylphenol, o-phenyl-phenol, o-isopropylphenol, 2-methyl-6-cyclopentylphenol, o and m-chlorophenol or 2,3,6-trimethylphenol. Preference is given to phenol, o- and m-cresol, 2,6-dimethylphenol, o-tert-butylphenol and o-phenyl-phenol, most preferred is phenol.

worin
R¹ für einen linearen oder verzweigten C₁-C₁₈-Alkylrest, bevorzugt C₁-C₆-Alkylrest, steht und
R² für einen linearen oder verzweigten C₁-C₁₈-Alkylrest, bevorzugt C₁-C₆-Alkylrest, oder einen C₆-C₂₄-Arylrest, bevorzugt einen C₆-C₁₂-Arylrest, steht oder
R¹ und R² zusammen für einen linearen oder verzweigten C₄-C₁₈-Alkylenrest, bevorzugt C₄-C₁₂-Alkylenrest stehen.Suitable ketones are, for example, those of the general formula (III),

wherein
R ^{1 is} a linear or branched C ₁ -C ₁₈ -alkyl radical, preferably C ₁ -C ₆ -alkyl radical, and
R ^{2 is} a linear or branched C ₁ -C ₁₈ -alkyl radical, preferably C ₁ -C ₆ -alkyl radical, or a C ₆ -C ₂₄ -aryl radical, preferably a C ₆ -C ₁₂ -aryl radical, or
R ¹ and R ² together represent a linear or branched C ₄ -C ₁₈ -alkylene radical, preferably C ₄ -C ₁₂ -alkylene radical.

Examples are suitable ketones of the general formula (III) Acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, Diethyl ketone, acetophenone, cyclohexanone, cyclopentanone, methyl, Dimethyl and trimethylcyclohexanones, which are also geminal methyl groups may have, for. For example, 3,3-dimethyl-5-methylcyclohexanone (Hydroisophoron). Preferred ketones are acetone, acetophenone, cyclohexanone and its homologues carrying methyl groups, particularly preferred is acetone.

C ₁ -C ₆ -alkyl is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3 Methylbutyl, neo-pentyl, 1-ethylpropyl, cyclohexyl, cyclopentyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4- Methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1, 2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl or 1-ethyl-2-methylpropyl, C ₁ -C ₁₈ alkyl moreover, for example, furthermore beyond, for example for n-heptyl and n-octyl, pinacyl, adamantyl, the isomeric menthyl, n-nonyl, n-decyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl or stearyl.

C ₁ -C ₆ -alkylene or C ₁ -C ₁₈ -alkylene, for example, represents the alkylene groups corresponding to the preceding alkyl groups.

C ₅ -C ₁₂ -cycloalkyl is, for example, cylopentyl, cyclohexyl, cyclooctyl or cyclododecyl.

Examples of C ₆ -C ₂₄ -aryl or C ₆ -C ₁₂ -aryl are phenyl, o-, p-, m-tolyl, naphthyl, phenanthrenyl, anthracenyl or fluorenyl.

halogen may be preferred for fluorine, chlorine, bromine or iodine Fluorine or chlorine, particularly preferably chlorine.

That the production of bisphenol A can be carried out in acidic ion exchange resins as catalyst-containing fixed bed reactors in which the ion exchange bed is purged with phenol at intervals is out DE 197 57 570 A1 known. This interval purge can eliminate the creeping increase in pressure loss. After this purge, the original high amount of starting material can be fed back into the reactor. The caused by the flushing production loss is thereby made up for in a short time again. In addition, it has been found that the rinse also has a positive effect on the selectivity and reactivity of the fixed beds.

object a particularly preferred embodiment of the present invention The invention therefore further relates to a process for the preparation of bis (4-hydroxyaryl) alkanes by reaction of aromatic mono-hydroxy compounds in the p-position are not substituted with ketones containing at least one aliphatic Having group on the carbonyl function, in a condensation reaction, especially prefers bisphenol A from phenol and acetone to acidic ion exchange resins as a catalyst-containing and from top to bottom flow-through fixed bed reactors, characterized in that low-chloride and low-carbon quartz sand as a retention medium for the acidic ion exchanger is used.

The interval for rinsing with phenol is preferably chosen so that 30 to 3500 m ³ , particularly preferably 90 to 600 m ³ Eduktstrom per m ^{3 of} catalyst resin are passed through the reactor between two rinses. The ion exchange bed can be flushed with phenol from above, from below or alternately successively from above and below. The preferred practice is to rinse from below or alternately successively from below and from above. Based on the amount of ion exchange resin, the amount of phenol to be used for the rinse is 0.1 to 20 times, preferably 0.3 to 5 times, the catalyst volume. The temperature of the phenol used should be 40 to 150 ° C, preferably 45 to 120 ° C. During the rinsing process, the reactor can be rinsed once or even several times in succession. After the rinsing process, the amount of reactants fed into the reactor can again be increased by up to 35%, which entails a corresponding increase in productivity.

The use according to the invention is in the following exemplified by the condensation of phenol and acetone to bisphenol A, wherein the application of the invention Use is not limited to this reaction. The The following example is merely illustrative of the invention and is not to be considered as limiting.

Examples

Example 1:

• Schicht 1: 25–63 mm Korndurchmesser
• Schicht 2: 16–32 mm Korndurchmesser
• Schicht 3: 8–12 mm Korndurchmesser
• Schicht 4: 3–6 mm Korndurchmesser
• Schicht 5: 1–2 mm Korndurchmesser
• Schicht 6: 0,5–1,2 mm Korndurchmesser

It was 150 m ³ with the ion exchange resin Lewatit ^® K1221 (Lanxess AG) filled with a diameter of 5.70 m and a reactor volume as acid catalyst, a fixed bed reactor, with the volume of the catalyst charge 108 m ³ and the catalyst bed height was 4.25 m. For the retention of the fixed-bed catalyst, a quartz sand bed was used, which had the following stratification from bottom to top with the specified particle sizes:

• Layer 1: 25-63 mm grain diameter
• Layer 2: 16-32 mm grain diameter
• Layer 3: 8-12 mm grain diameter
• Layer 4: 3-6 mm grain diameter
• Layer 5: 1-2 mm grain diameter
• Layer 6: 0.5-1.2 mm grain diameter

Of the used quartz sand had a chloride content of less than 40 Ppm by weight, a carbonate content of less than 1000 ppm by weight, a Sulphate content of less than 200 ppm by weight, an iron content of less than 4400 ppm by weight, a potassium content of less than 250 Ppm by weight, a calcium content of less than 400 ppm by weight and a magnesium content of less than 400 ppm by weight.

Also after 15 years of operation of the fixed bed reactor with the quartz sand bed used in the invention was no breakdown of the catalyst, no clogging of the bed, no pressure increase and no signs of corrosion in the following Plant parts detected. An exchange of the invention used Quarzsandbettes was therefore not required, whereas the catalyst was changed several times during this time.

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

• - US 4391997 A [0002]
• US 4400555 A [0002]
• - US 4590303 A [0002]
• - EP 210366 A [0002]
• US 2004/0068085 A1 [0003, 0004]
• - DE 19757570 A1 [0004, 0006, 0039]
• - EP 1480993 B1 [0007]
• - DE 19757570 A [0016]
• US 2004/0068085 A [0016]

Claims (10)

Use of low-chloride and low-carbonate quartz sand as a retention medium for catalysts based on solid acids in fixed bed reactors. Use according to claim 1, characterized characterized in that as the low-chloride and low-carbon quartz sand, such (r) with a chloride content of less than 1000 ppm by weight, preferably of less than 200 ppm by weight, and a carbonate content of less as 5000 ppm by weight, preferably less than 2000 ppm by weight, respectively based on the total weight of the chloride and carbonate poor quartz sand used will be). Use according to claim 1 or 2, characterized in that acidic catalysts are those with a pK _a value of less than 4, preferably less than 2, more preferably less than 1. Use according to at least one of claims 1 to 3, characterized in that as acidic Catalysts acidic ion exchange resins can be used. Use according to at least one of claims 1 to 4, characterized in that the retention media in fixed bed reactors for condensation reactions, preferred for the preparation of bis (4-hydroxyaryl) alkanes, especially preferably used for the preparation of bisphenol A. become. Use according to at least one of claims 1 to 5, characterized in that the fixed bed reactors flowed through from the reaction medium from top to bottom. Use according to at least one of claims 1 to 6, characterized in that the Fixed bed reactors flowing through an acidic reaction medium Medium is. Process for the preparation of bisphenol A from phenol and acetone in acidic ion exchange resins containing as catalyst and from top to bottom flowed through fixed bed reactors, characterized in that low-chloride and low-carbon quartz sand as a retention medium for the acidic ion exchanger is used. A method according to claim 8, characterized in that the ion exchange bed at intervals with phenol, wherein between two rinses 30 to 3500 m ³ Eduktstrom per m ^{3 of} catalyst resin are passed through the reactor and the temperature of the phenol used is 40 to 150 ° C. A method according to claim 8 or 9, characterized in that the ion exchange bed successively flushed with phenol from below and from above.