CS221373B1 - Method of isolation of the pyrocatechine and its homologues from phenol mixtures - Google Patents

Description

The invention relates to the preparation of pyrocatechin and its homologues by isolation from phenolic mixtures obtained from the products of coal gasification and carbonization.

In the gasification and carbonization of coal, in addition to the main product of the generator gas, which after treatment is mainly recovered as fuel gas, low-temperature tar and waste phenolic water are obtained.

The residual tar and phenolic water contain monovalent and divalent phenols and other oxygen compounds.

There is a commercial interest in monovalent and bi-valent phenols and therefore these are acquired.

An important raw material for the preparation of divalent phenols is the phenosolvan extracts, which are obtained during the de-phenolization of water leaving during gasification and carbonization of coal and further recovery of low-temperature tar, the phenosolvan extracts obtained at individual gasworks or carbonization plants are usually processed centrally. The phenol / cresol mixture is first distilled off from the phenosoilvane extract or its s-moiety, and the di-ammonium phenol concentrate, containing mainly pyrocatechin and its homologues, is distilled off from the distillation residue obtained. This concentrate is a suitable raw material for the isolation of pyrocatechin and its homologues.

In isolating pyrocatechin, it is utilized that pyrocatechin is excreted from the divalent phenol concentrate in crystalline form; The precipitated pyrocatechin crystals are separated by filtration or centrifugation. To isolate pyrocatechin from this feedstock, the pyrocatechin concentrate is mixed with a solvent, for example in a 1: 1 ratio, and the mixture is heated to 70-80 ° C. The solution obtained is gradually cooled to a temperature of 5 to 25 ° C, whereby crystals of pyrocatechin precipitate and are centrifuged.

The following substances have been used operationally as a solvent:

benzene, toluene, xylenes, hydrocarbonised An added hydrocarbon of fraction 90-110 ° C containing about 70% aromatics, trichloroethylene, ethylbenzene and vio-d-a. The pyrocatechin obtained usually had a pour point of 102 ° C and was suitable for most applications.

The yield of pyrocatechin greatly influences the content of pyrocatechin in the feedstock. With a pyrocatechin content of the feed concentrate of 40 to 60%, crystalline pyrlocatechin was obtained in a yield of 25-45%.

It has now been found that pyrocatechin can be obtained in a high yield, typically over 75%, from a bivalent phenol concentrate distilled from the phenolsolvane-carbon extract by distillation. In this new distillation process, the divalent phenol concentrate is distilled with hydrocarbon fractions boiling usually in a distillation range of 150 to 280 ° C, utilizing the fact that pyrocatechin is mixed with the hydrocarbons into the distillate.

From the distillate obtained, the pyrocatechin is separated either by separating the precipitated crystals by centrifugation or by washing the pyrocatechin from the distillate with water and separating it as an aqueous pyrocatechin solution.

Similarly, distillation of 4-methylpyrocatechin and 3-methylpyrocatechin and other pyrocatechin homologs can be concentrated. For the purpose isolation of these pyrocatechin homologues, it is advantageous to use a hydrocarbon fraction of 200-230, optionally a fraction of 220-250 [deg.] C., for distillation z-ionization.

For the isolation of pyrocatechin from the phenolic mixture, both individual hydrocarbons and hydrocarbon mixtures can be used. When working with pure hydrocarbons, it has been found that pyrocatechin and its hiomoilogs form azeotropic mixtures which allow it to be distilled off from the mixtures. For example, pyrocatechin, boiling at 245.9 ° C at atmospheric pressure, forms, for example, the following azeotropic mixtures:

Boiling point azeotropic The content of pyrocatechin in the mixture ° C of the azeotropic mixture ° C

naphthalene 217.4 11.5 1-methylnaphthalene 235.1 40 2i-Methylnaphthalene 233.25 37 1,3,5-trimethylbenzene 214.7 8.9 tridecan 229.7 30

In practice, it is preferable to work with a hydrocarbon mixture. As has been found, it is advantageous to use a petroleum distilled hydrocarbon fraction or even narrower fractions, for example 180 to 190 ° C, 190 to 200 ° C, for the isolation of pyrocatechin. As already mentioned, it is preferable to work with higher-boiling fractions when isolating pynocatechin homologs. The advantage of using these petroleum fractions is that they are substantially cheaper and more affordable than pure hydrocarbons. Also, regeneration and recirculation of mixtures is easier and easier.

In attempts to isolate pyrocatechin and its homologues from a bivalent phenol concentrate, a petroleum fraction, which is operationally produced from petroleum so-called jet kerosene with the following characteristics, was used:

density at 20 ° C 0.770 start of boiling point ° C 175 ° / o distilled 190 ° C% distilled 200 end boiling point 245 ° C

Composition of hydrocarbons obtained by FIA method and mass spectroscopy in% m / m.

alkanes 41.8 noncondensed cycloalkanes 21.8 condensed cycloalkanes 14.0 alkylbenzenes 12.0 indanes and tetralines 6.7 alkylnaphthalenes 1.9 benzothiophenes 1.3 aromatics according to FIA method. 18.6

The isolation of pynocatechin and its homogenees can be carried out with the entire oil fraction of 175-245 ° C or with a narrower fraction, for example 170-190 ° C.

Similarly, the isolation can be carried out with a commercially produced non-decane fraction of 145-180 ° C or its fraction of 160-180 degrees Celsius, containing about 95% of the alkanes.

In the distillation isolation of pynocatechin, high yields of pyrocatechin can also be achieved with a two-valent phenol concentrate which also contains a lower pyrocatechin content, for example 15-25%.

In the experiments described in Examples 1 to 3, a divalent phenol concentrate having the following composition was used:

(by chromatographic analysis in% by weight).

water 2.7 neutral oils 1.8 phenol 1.7 o-cresol 0.2 m-p-cresol 2.4 2.4 + 2.5 xylenol 0.7 2.3 + 3.5 xylenol 4.6 3,4 xylenol + + naphthalene + + 2,3,6-trimethylphenol. 3.4 2,3,5-trimethylphenol 2.2 pyrocatechin 35.5 3-methylpyrroleocatechin 15.3 4-methylpyrocatechin 20.6 hydrjochinini + + resorcin + + higher boiling proportions. 8.9 Example 1

Pyrocatechin was separated from the phenolic feedstock by means of an oil fraction of 170-190 ° C as a hydrocarbon separating agent on a discontinuous distillation column of 10 theoretical plates. Distilled at reflux ratio 1; 5 at atmospheric pressure and at the head temperature up to a maximum of 190 ° C.

Crystalline pyrocatechin was centrifuged from the distillate obtained after cooling; the distillate was cooled to 20-25 ° C.

The hydrocarbon fraction after centrifugation of the pyrocatechin and the hydrocarbon fraction separated from the distillation residue were mixed and used in the next batch.

Balance data in kg:

Entry to distillation:

phenolic raw material 100 petroleum fraction 170-190 ° C 700

Distillation output:

overhead product from which 29 kg of pyrocatechin 592 crystallized a distillation residue containing phenolic raw materials and 62.53 petroleum fractions 145.47

28.71 kg of centrifuged crystalline pyroacetylene was obtained. The yield of pyrocatechin was 80.87%.

The obtained crystalline pyrocatechin had, according to chromatographic analysis, the following characteristic in% by weight:

neutral oils + hydrocarbons 0.4 monovalent phenols 0.04 pyrocatechin 99.0

3-methylpyroicatechin 0.36

4-methylpyrrocatechin 0.1 hydroquinone, resorcin and other proportions 0.1

Example 2

Catechol from phenol feedstock separated using petroleum fraction 180-190 ° C as the hydrocarbon separation · ¹ reagent under the conditions described in Example no. 1.

Crystalline pyrocatechin was obtained in a yield of 92.25% by weight.

Its quality was as follows:

neutral oils + hydrocarbons 0.7% wt.

monovalent phenols 0.3 pyrocatechin 97.7

3-methylpyrlocatechin 0.5

4-methylpyrocatechin 0.3 hydroquinone, reslorcin and other proportions 0.5 Example 3

Pyrocatechin was separated from the phenolic feedstock by a hydrocarbon fraction of 160-180 ° C, obtained after distillation of lighter fractions from a commercially produced non-decane fraction having a density at 20 ° C of 0.749 n and a discontinuous column of 10 theoretical plates.

221S at a reflux ratio of 1: 5. Distillation was carried out at atmospheric pressure and head temperature to; max. 185 ° C.

Balance data in kg:

Entry to distillation:

phenolic feedstock 100, petroleum fraction 160-180 ° C 700

Distillation output:

a head product from which 27.05 kg of pyrocatechin 572 has crystallized

Claims (1)

Process for the isolation of pyrocatechin and its homologues from phenolic mixtures obtained from coal gasification and carbonization products, characterized in that pyrocatechin and its homologues are separated from the phenol mixture by distillation with hydrocarbons boiling in the range of 150 to 280 distillation residue containing phenolic raw materials 63.72 and petroleum fractions 164.28 The yield of pyrocatechin was 76.2%. Its The quality was as follows: neutral oils + hydrocarbons 1.2% w / w monovalent phenols 0.5 pyrocatechin 97.3 3-methylpyrocatechin 0.5 4-methylpyrocatechin 0.3 hydroquinone + resoircin + others shares 0.2 The invention relates to the isolation of pyrocatechin with a hydrocarbon fraction preferably in the range of 180 to 220 ° C and to the isolation of homologues of the pyrocatechin with a hydrocarbon fraction boiling in the range of 220 to 250 ° C.