DE19757530C2 - Process for the isolation of carbazole and production of 9,10-dihydroanthracene from crude anthracene - Google Patents

Description

The present invention relates to a method for iso lation of carbazole and production of 9,10-dihydro anthracene from crude anthracene comprising the partial hy Dration of enriched raw anthracene and one closing solvent crystallization of the hydrogenation pro product of the enriched raw anthracene.

In technical coal tar distillation falls in addition to light oil, medium oil, heavy oil and pitch in the boiler range from 270-400 ° C to the so-called anthracene oil. This raw anthracene oil is cooled and there in the case of precipitating crystal mass by filtering or Centrifugation separated. You get this way two raw products, the raw anthracene and the filtered or thrown off anthracene oil. The raw anthracene ent in addition to anthracene, mainly holds carbazole, phenanthrene and Fluorene.

Carbazole is used in the manufacture of various Dyes, insecticides and vinyl carbazole application. Partial is also of industrial importance Hydrogenation product of anthracene, 9,10-dihydroanthracene, that as a raw material for the production of Anthra quinone serves. In obtaining these two substances zen, carbazole and 9,10-dihydroanthraquinone, therefore exists an increased interest.

The extraction of carbazole from raw anthracene via a Crystallization step causes problems since carbazole and anthracene always together in a certain ver crystallize relationship to each other.  

Extractive methods of removal are known from the literature tion of carbazole from anthracene oils.

This is described in Koks, Smola, Gaz (1986), 31 (4), 65-7 first remove raw anthracene from the anthracene oil nen and this anthracene oil then to obtain car separate bazole and anthracene. The separation of the Crude anthracene from the anthracene oil takes place through a crystallization step using metha nol and hydrocarbons in the form of paraffins, aro matic alkyl hydrocarbons as well as naphthenes Solvents. The ones formed during crystallization Raw anthracite crystals can be separated by conventional methods such as filleting or hurling off the mother caustic be separated. The raw anthracene is on closing with N-methylpyrrolidone and optionally 10% Water in two stages at such low temperatures ex trahts that there is little anthracene in N-methylpyrro lidon triggers while the other components of the Rohan thracens, especially carbazole and phenanthrene, with the N- Form methylpyrrolidone complexes and thus be separated can. The carbazole can be extracted from the extractant two ways can be won. For one, you can go through first Addition of water to a carbzole / phenanthrene fraction be separated from the following with pyrolytic oil crude carbazole is extracted as an extracting agent and from is finally recrystallized. On the other hand can the N-methylpyrrolidone extract is initially N-methyl pyrrolidone driven off and the distillation residue to Separation of carbazole and phenanthrene then a fraction crystallization from pyrrolytic oil be opened. A disadvantage of this in the sum of many stages The main issue is the complexity. Since the car bazole portion in the Rohan used for extraction traces are also relatively low and, for example, only  Can be 10 wt .-%, large amounts of solvent what needed in the different extraction steps reduces the economic attractiveness of the process.

US-A-33 31 853 describes a method for isolation of anthracene and carbazole from an anthracene, carbazole and raw anthracene oil containing phenanthrene. The raw is first mixed with an aromatic kohlwas treated with toluene or xylene. When cooling below 25 ° C an anthracene and carbazole containing falls Crystal material from which after separation from the mother liquor is suspended with the pure solvent. The This suspension is worked up by distillation in addition to the pure solvent anthracene on an upper floor the distillation column, while pure carbazole dated Distillation bottoms is withdrawn.

According to the process known from US Pat. No. 3,624,174, next contain the anthracene, phenanthrene and carbazole ing raw product with an azeotropic solution medium, such as ethylene glycol or ethylene carbonate and subjected to distillation. The solvent add rate increases the volatility of anthracene and phenanthrene versus carbazole. From the distillate after cooling, pure anthracene is obtained, while phenane remains in the mother liquor. Carbazole enriches itself in the distillation residue and can from this obtained by recrystallization with, for example, xylene become.

According to US-A-33 31 853 and US-A-36 24 174 is an expense some distillation necessary.

The object of the present invention is a new and more powerful process available too  make the provision of both carbazole and also of 9,10-dihydroanthracene from crude anthracene professional way with high selectivity and good at the same time Overall yield enabled.

This object is achieved by a process for the isolation of carbazole and the production of 9,10-dihydroan thracen from crude anthracene which contains anthracene, carbazole and phenanthrene, comprehensively

• 1. the use of raw anthracene containing 20-50% by weight Anthracene, 10-40% by weight carbazole, 15-30% by weight Phenanthrene and 0-15% by weight fluorene together with a residual oil from pure naphthalene production in a suspension crystallization, whereby the Residual oil from pure naphthalene production in one Mixing vessel to a temperature of 100-180 ° C warmed, the Rohanthracen adds and at one Temperature of 100-180 ° C stirred until the raw anthracene has gone into solution, and then the solution to a temperature of 50-100 ° C to form a Cools crystal goods from enriched raw anthacen,
• 2. Separation of this crystal material from enriched Raw anthracene from the mother liquor,
• 3. Performed continuously or discontinuously partial hydrogenation of the separated crystal from step (2) at a reaction temperature of 150-300 ° C, a reaction pressure of 40-100 bar Hydrogen and a reaction time of 2-8 h in  Presence of a sulfur resistant catalyst un ter obtaining a hydrogenation product, sulfidakti fourth catalysts are used in addition to Group VIII metals of Periodensy contain tungsten or molybdenum oxide and counter if necessary on aluminum oxide, silica or Gemi of which are applied as a carrier material and contain basic promoter oxides that are selected are from groups IA, IIA, lanthanides and the actinides of the periodic table, and
• 4. Workup of the hydrogenation product from step (3) by solvent crystallization in an aroma table solvent to form a second Crystal goods containing at least 90% carbazole holds.

The raw anthra used in the process according to the invention cen usually comes from the processing of carbo stocky raw tar and contains anthracene, carbazole and Phenanthrene and optionally fluorene. Is preferred Raw anthracene, which contains 30-40% by weight anthracene, 20-30% by weight  and in particular 20-25% by weight carbazole, 20-30% by weight Phenanthrene and 3-6 wt .-% fluorene contains. Given if the crude anthracene also contains methylfluorenes, Methylphenanthrene, methylanthracene.

In addition, small amounts of sulfur, e.g. B. in Form of diphenyl sulfide, usually included in the Range of 1000-5000 ppm, corresponding to 0.1 to 0.5%.

That in the suspension crystallization together with the Residual oil of pure naphtha used in raw anthracene Line production is known as naphthalene drip oil draws and preferably contains 30-60 wt .-%, in particular 40-50% by weight, naphthalene, 10-30% by weight, in particular 20- 30% by weight, methylidenes, 1-10% by weight, in particular 1-5 % By weight, methylnaphthalene and 1-10% by weight, in particular 4- 8% by weight, indene.

The suspension crystallization of the crude anthracene together with the residual oil according to the pure naphthalene production Step 1 of the method according to the invention is carried out leads by first the residual oil of the Reinnaph Thalin production in a stirred tank to a temperature heated from 100-180 ° C, then add the raw anthracene and stirring at the temperature of 100-180 ° C until the Rohanthracen has gone into solution. Then will the solution within a period of 3-6 hours Temperature of 50-100 ° C, preferably 60-90 ° C cooled where the enriched raw anthracene as crystal crystallized.

The resulting from the suspension crystallization Crystalline is according to step (2) of the invention Mother liquor process, d. H. the supernatant Solution separated. This separation is usually carried out  in a centrifuge, which is preferably heated. The off separate mother liquor can be treated as without further treatment Mixing component for the production of technical aromatic Oils are used.

The isolated crystal contains essentially carba zol and anthracene. For the successful, further Ver It is crucial in the course of the overall procedure that through the suspension crystallization the share of all others components contained in the raw anthracene, such as phenanthrene, Fluorene, methylfluorene, methylphenanthrene and methylane thracene is significantly reduced. The crystal good of Suspension crystallization is therefore also considered chertes Rohanthracen called. This preferably contains Crystal material from enriched raw anthracene 35-60% by weight, preferably 50-60% by weight and in particular 50-55% by weight Anthracene, 15-40 wt .-%, preferably 30-40 wt .-% and ins particularly 30-35% by weight carbazole, 1-25% by weight, preferred 1-10 wt .-% and in particular 1-5 wt .-% phenanthrene and 1-8% by weight, preferably 1-5% by weight and in particular 1-3 Wt% fluorene. This means that the enriched Raw anthracene in total up to 95% from carbazole and Anthracene can exist. The carbazole yield of the Sus Pension crystallization is 65-75% based on the carbazole in crude anthracene.

The crystal material separated out in step (2) chertem Rohanthracen is in step (3) of the method partial hydrogenation in the presence of sulfur resi Stenter hydrogenation catalysts subjected.

Sul as hydrogen-resistant hydrogenation catalysts finely activated catalysts in addition to oxides of metals from group VIII of the periodic table tungsten or contain molybdenum oxide. These are catalysts optionally on a support material such as aluminum  oxide, silica or mixtures thereof applied and optionally contain basic promoter oxides that are derived from are selected from groups IA, IIA, lanthanides and the actinides of the periodic table. Particularly suitable are sulfided Co / Mo, Ni / Mo or Ni / W catalysts. The sulfidation of the catalysts before use in the Hydrogenation is preferably carried out using Dimethyl disulfide. The sulfided catalyst is in the subsequent hydrogenation tests usually as a fixed bed used.

Suitable catalysts are described, for example, in US Pat. 4,720,477, EP-A-0 389 119, EP-A-0 082 726 and EP-A-0 046 634. At the revelation of this Catalysts in the cited documents are hereby specifically referred to.

The hydrogenation of the enriched raw anthracene can be carried out continuously or discontinuously. Prefers is worked discontinuously. For this, the is enriched raw anthracene in a reaction vessel, at for example a stirred autoclave, submitted with the sus pendulous form of the sulfided catalyst and the mixture is preferably heated to 170-220 ° C 190-210 ° C, melted.

The sulfided hydrogenation catalyst is used in an amount of 5-10%, based on the total reaction mixture, used. The hydrogenation is at a reaction temperature rature of 150-300 ° C, preferably 240-290 ° C and a reak tion pressure of 40-100 bar, preferably 50-70 bar water material and a reaction time of 2-8 h, preferably 4-5 h, carried out.

In this partial hydrogenation, the anthracene content of the raw anthracene selectively and largely completely 9,10-dihydroanthracene is hydrogenated while the carbazolane part of the raw anthracene remains unchanged.  

The hydrogenation product of the enriched raw anthracene Step (3) is carried out in step (4) by a solvent worked up crystallization. For this, the hydrogenation product in an aromatic solvent, preferred dissolved by increasing the temperature to 70-130 ° C. As aromatic solvents are preferred BTX aromatics (Benzene / toluene / xylene) used. The solution obtained is then heated to a temperature of 0-30 ° C cooled. That with the solvent crystallization tion second crystal is formed by filtration optionally separated with a subsequent washing step and dried. The selectivity of this Solvent crystallization with regard to the carbazole is excellent. There are at least 90 in the crystal % By weight, preferably at least 95% by weight and in particular contain at least 96 wt .-% carbazole.

A carbazole out results for the overall process Loot of 63-72%, based on the carbazole in the set raw anthracene.

Only by connecting the steps (1) in series to (4) in the process according to the invention, the Isolate carbazole in the yields mentioned. The Suspension crystallization is characterized in that which alongside carbazole and anthracene in crude anthracene held and also referred to as ballast components Substances are removed in a targeted manner, at the same time Increase in the proportion of carbazole and anthracene enriched raw anthracene. Because at least some of the ballast components of a hydrogenation would have their Absence or only low concentration in the angerei chere Rohanthracen result in the hydrogenation a smaller amount of hydrogen is required. Simultaneously A higher mass throughput can be used in the hydrogenation the target compound carbazole can be achieved. Both  Effects contribute to the profitability of the overall process rens positive.

The following solvents also work accordingly The only reason crystallization is so excellent is because of that occurring hydrogenation product of the enriched raw anthracene apart from carbazole and 9,10-dihydroanthracene, only small amounts other hydrogenated or unhydrogenated ballast contains substances that negatively affect the quality of crystallization could influence.

Examples I suspension crystallization of crude anthracene with Naphthalene drip oil

1000 g of naphthalene dropping oil of those given in Table 1a Composition are pre-mixed in a 4 L stirred tank sets and heated to 170 ° C. Then portions instruct a total of 1000 g of crude anthracene in Table 1b given composition and added at 170 ° C. completely dissolved. The solution will then be with stirring for a period of about 4 hours cooled to 80 ° C, with an enriched raw anthracene crystallized. The entire crystal suspension is in transferred to a centrifuge heated to 80 ° C, in which the Crystal material from enriched raw anthracene from the Mother liquor is separated. This gives 457 g Crystal material of the composition given in Table 1.  

Table 1a

Table 1b

II Discontinuous hydrogenation of enriched Raw anthracene according to step 3 of the invention Procedure a) Sulfidation of the hydrogenation catalyst

In the following Examples II-3,7 and 8 regarding the hydrogenation step uses Co / Mo catalysts with 4% Cobalt oxide and 14.5% molybdenum oxide on an aluminum nium oxide carrier used. It is about Commercial products from BASF AG with the designations BASF M8-12 and M8-14. In Examples II-1, 2, 4, 5 and 6 is a Ni / Mo catalyst with 1-10% cobalt oxide and weni less than 25% molybdenum on an aluminum oxide / silica Carrier used.

Before the hydrogenation catalysts are used, these become before sulfidation in the presence of dimethyl disulfide  subject. This is in a 2 L reaction tube introduced catalyst with 1.5 kg of a 67% solution of dimethyl disulfide in 38 kg mineral oil at 225 to 300 ° C under a hydrogen atmosphere (240 L exhaust gas / h) at one Throughput of 1.0 V / Vh (volume of liquid educt (attached enriched crude anthracene) / (volume of catalyst × h)) Sulfurized for 15 hours. The temperature gradient between 225 and 300 ° C is 3 ° C per hour.

b) hydrogenation

The enriched crude anthracene is hydrogenated discontinuously in a stirred autoclave. The together setting of the starting material used as starting material Raw anthracene is shown in Table 2. In which Enriched crude anthracene used in Example II-1 it is that described in point I Suspension crystallization product obtained.

First of all, the crystal material is added Raw anthracene was introduced into the stirred autoclave. The hydrogenation catalyst is then suspended Form added and the mixture heated up 200 ° C melted. The one in the respective experiments amount of catalyst used and the remaining reaction conditions such as reaction temperature, reaction pressure and Re Action times are summarized in Tables 3, 4 and 5 poses.  

Table 2

Example II-1

Table 3

Examples II-2 and 3 (variation of the catalyst)

Table 4

Examples II-4-6 (variation of reaction pressure)

Table 5

Examples II-7 and 8 (variation of reaction time)

III solvent crystallization of that obtained in II Hydrogenation product of the enriched raw anthracene

100 g of the hydrogenation product of the enriched raw anthra cens from Example II-1 with that given in Table 6 Compositions are dissolved in 400 mL toluene at 100 ° C. The solution is then poured to 20 ° C. with stirring cools. The precipitated crystal is filtered off separated from the mother liquor, with 40 mL fresh toluene covered and then dried. The composition of the crystal is shown in Table 6. Contain are 97.4% carbazole.

Table 6

Claims (9)

1. Process for the isolation of carbazole and manufacture of 9,10-dihydroanthracene from crude anthracene, which contains anthracene, carbazole and phenanthrene, to comprehensively

• 1. the use of raw anthracene, containing 20-50 wt .-% anthracene, 10-40 wt .-% carbazole, 15-30 wt .-% phenanthrene and 0-15 wt .-% fluorene together with a residual oil from the Pure naphtha line production in a suspension crystallization, whereby the residual oil of the pure naphthalene production is heated to a temperature of 100-180 ° C in a stirred vessel, the crude anthracene is added and the mixture is stirred at a temperature of 100-180 ° C until the crude anthracene has dissolved. and then the solution is cooled to a temperature of 50-100 ° C. to form a crystal of enriched crude anthracene,
• 2. separation of this crystal material from enriched raw anthracene from the mother liquor,
• 3. continuously or batchwise carried out partial hydrogenation of the separated crystalline material from step (2) at a reaction temperature of 150-300 ° C., a reaction pressure of 40-100 bar of hydrogen and a reaction time of 2-8 h in the presence of a sulfur-resistant catalyst lysators to obtain a hydrogenation product, where sulfide-activated catalysts are used who, in addition to oxides of metals from group VIII of the periodic table, contain tungsten or molybdenum oxide and are optionally applied to aluminum oxide, silica or mixtures thereof as carrier material and contain basic promoter oxides, which are selected are from groups IA, IIA, the lanthanides and the actinides of the periodic system, and
• 4. Working up of the hydrogenation product from step (3) by solvent crystallization in an aromatic solvent to form a second crystal material which contains at least 90% carbazole.

2. The method according to claim 1, characterized in that that the raw anthracene 30-40 wt .-% anthracene, 20-30 % By weight and in particular 20-25% by weight of carbazole, 20-30 % By weight of phenanthrene and 3-6% by weight of fluorene. 3. The method according to claim 1 or 2, characterized records that in the suspension crystallization re used together with the raw anthracene base oil of pure naphthalene production 30-60% by weight, in particular 40-50% by weight, naphthalene, 10-30% by weight, in particular 20-30% by weight, methylindene, 1-10% by weight, in particular 1-5% by weight, methylnaphthalene and 1-10 % By weight, in particular 4-8% by weight, contains indene. 4. The method according to one or more of claims 1 to 3, characterized in that the Sus Pension crystallization according to step 1 with Rohan thracen offset and heated to 100-180 ° C back base oil of pure naphthalene production within a Period of 3-6 h to a temperature of 60-90 ° C is cooled.   5. The method according to one or more of claims 1 to 4, characterized in that the crystal from enriched raw anthracene 35-60 wt .-% before add 50-60 wt .-% and in particular 50-55 wt .-% An thracen, 15-40 wt .-%, preferably 30-40 wt .-% and ins particularly 30-35% by weight carbazole, 1-25% by weight, preferred 1-10 wt .-% and in particular 1-5 wt .-% phenanthrene and 1-8% by weight, preferably 1-5% by weight and in particular 1-3 Wt .-% contains fluorene. 6. The method according to claim 1, characterized in that sulfided Co / Mo, Ni / Mo or Ni / W catalysts be used. 7. The method according to claim 1, characterized in that the hydrogenation of the enriched crude anthracene in step (3) at a reaction temperature of 240- 290 ° C and a reaction pressure of 50-70 bar water fabric is carried out. 8. The method according to claim 1 or 7, characterized records that the hydrogenation of the enriched Rohanthracens in step (3) with a reaction time from 4-5 h is carried out. 9. The method according to one or more of claims 1 to 8, characterized in that the hydrogenation product for solvent crystallization in the aromatic Solvent while increasing the temperature to 70-130 ° C dissolved and then stirring to a Temperature of 0-30 ° C is cooled.