CS270979B1 - Method of phenols refining - Google Patents

Abstract

The solution concerns the refining of phenols obtained from liquid products when burning fossil fuels. The solution is based on the fact that the phenols get brought to a temperature of 50 to 400 degrees Celsius under a pressure of 0.01 to 10 MPa and in the presence of Raney's nickel.

Description

The invention relates to a process for refining phenols obtained in the treatment of fossil fuels.

When the phenolysis of liquid coal products by extraction methods, unwanted ballast substances pass into the phenolate solution, which strongly contaminate and degrade the resulting final phenolic products. Of the sulfur undesirable substances, this applies to thiophenols, sulfides, disulfides, alkylthiols, etc.

Technical phenol distilled from crude phenols boiling between 1 and 0 to 225 ° C of low-temperature lignite tar, in which about 0,05% of sulfur, contains 0,01 to 0,02% by weight of sulfur. In the cresol and xylenol fractions, the sulfur content is greater and gradually increases with the boiling point of the phenolic products, reaching 0.02-0.07% by weight. open.

The concentration of sulfur in the phenols obtained from crude oil by extraction with alkali metal hydroxides is 0.05 to 1.5% by weight.

The refining of the crude phenols is now carried out by selective extraction with light paraffinic gasoline or steam steaming, which is associated with the conversion of phenols into alkali metal phenolates. Reduction of undesirable components can also be achieved by contacting them with large surface adsorption materials such as activated carbon, etc., or by distilling phenols with the addition of sulfuric acid.

However, all of these processes have a number of disadvantages. In particular, the content of sulfur compounds when used in refining generally does not fall below 0.10. There are many undesirable products. Processes are energy intensive, disposal of contaminated activated carbon is difficult, etc.

Catalytic hydrogenation processes are more preferred in the phenol refining process, where, under appropriately selected reaction conditions, the sulfur groups are degraded while the hydroxyl group is retained. Processes using molybdenum disulphide, tungstic and oxides of both metals have been tested in the past. Low-pressure phenol refining processes on nickel and cobalt sulphide deposited in an amount of about 16.5% by weight on sodium aluminate have also been developed.

Thiophenols can be removed from phenols by adsorption on a lead sponge and iron obtained by reduction from ferric oxide with hydrogen can also be utilized. Desulphurization also occurs by reduction of the hydrogen formed by the reaction of zinc in an alkaline phenolate medium at a temperature of about 90 ° C, optionally using reducing agents such as FeCl 2 and the like.

In all these cases, the desulfurization is imperfect, even these processes are time and economically demanding and many side reactions reduce the phenol yields because the desulfurization reactions are not selective.

These drawbacks are overcome by the process of the invention comprising subjecting phenols extracted from liquid fossil fuel treatment products to an activated Raney nickel in the reactor at elevated temperature and reduced and / or elevated pressure. In this process, sulfur binds to the surface of the refining catalyst and its concentration in the refined phenol product is less than 10 ppm. A further advantage of the process according to the invention is that the deactivated refining catalyst can be reactivated by treatment with sodium hydroxide, potassium hydroxide solution, etc.

The method of carrying out the invention is described in more detail in the following examples.

Example 1

The xylenol fraction obtained in the extraction of phenols from lignite tar with the parameters water content of 0.1% by weight, sulfur content of 180 ppm, pyridine base content of 0.2% by weight, content of

CS 270 979 B1

2-methylphenol 0.2 4 wt.%, 3- and 4-methylphenol; 21 wt.%, 2,4- + 2,5-dimethylphenol 27 4 wt., 2,3- + 3,5-dimethylphenol 17%. %, 2,6- + 3,4-dimethylphenol 4% by weight, was heated in an amount of 100 g for 1 hour in the presence of 1 g of activated Raney nickel under nitrogen to 190 ° C in a flask under reflux. The sulfur content of the refined product after filtration and distillation decreased from the original 180 ppm to 4 ppm.

Example 2

The xylenol fraction characterized in Example 1 was first heated to boiling for 10 minutes in the presence of 1 wt.% Activated powdered Raney nickel and precooled in the presence. The distillation residue content was 10% by weight. The sulfur content of the distillate was even 3 ppm.

Example 3

No.

The xylenol fraction of the parameters given in Example 1 was repeatedly filtered through an activated Raney nickel layer at 160 ° C by filtering the 100 ml fraction through a 5 g catalyst layer and 0.4 cm layer thickness at a rate of 3 ml / min. . The sulfur content of the refined fraction fell to 5 ppm after precooling.

Example 4

100 ml of the xylenol fraction characterized in Example 1 was poured into the gaseous 2-ml Raney activated catalyst in each case and the reaction mixture was always kept for 30 min. heated to 165 ° C under a pressure of 0.08 MPa in a nitrogen atmosphere. The refined fraction was always distilled. The sulfur content of the distillate in all cases did not exceed 5 ppm.

Claims (1)

Process for refining phenols obtained from liquid fossil fuel treatment products, characterized in that the phenols are heated in the presence of Raney nickel to a temperature of 50 to 400 ° C at a pressure of 0.01 to 10 MPa.