JPH0244872B2 - TAARUSANNOSEISEIHOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for purifying tar acid. Tar oil, liquefied coal oil, or coal gasified condensate obtained by distilling coal tar, shale tar, oil gas tar, etc., contains tar acids, mainly phenols, cresols, and xylenols. , this is being recovered. To recover tar acids from tar oil, coal liquefied oil, coal gasification condensate, etc.
A method of separating tar salts through alkali extraction, decomposing them with acidic substances to produce crude tar acid, and then distilling this crude tar acid, or using liquid ammonium, hot water, alcohols, penzine, amines, and esters. A known method is to separate tar acid by extraction with , ether, ketone, etc., separate the extract to obtain crude tar acid, and then distill the crude tar acid. However, no matter which method is used, impurities such as neutral oils, tar bases, organic acids, sulfur compounds such as thiols derived from the raw materials are unavoidable from being mixed into the crude tar acid. These impurities can be removed to some extent in the subsequent purification distillation, but since tar acid is made up of various phenols and has a wide distillation temperature range, it is not possible to remove them sufficiently. It is difficult. In order to obtain high-purity tar acid, the removal of organic acids and tar bases is particularly important, and as a result of various studies on this method, the present inventors found that after removing carboxylic acids from crude tar acid in advance, found that a method for purifying tar acid characterized by contacting it with a cation exchange resin is extremely effective. The reason for removing carboxylic acids is that it has been found that their presence inhibits the abasing function of the cation exchange resin. Crude tar acid is separated from tar oil, coal liquefied oil, coal gasification condensate, etc., which is a distillate within the boiling point range of tar acid, and contains impurities such as carboxylic acid, organic base or neutral oil, and sulfur compounds. It includes. For example, crude tar acid obtained from coal tar oil by alkaline extraction and acid decomposition contains 2000 ppm and 1000 ppm of carboxylic acids, tar bases, and thiols, respectively, in addition to water.
and often contains 300ppm or more. It was found that washing with alkaline carbonate water is effective for removing carboxylic acids from crude tar acid. When washing with alkaline carbonate water, soda carbonate is suitable as the alkali carbonate, and is preferably used in the form of an aqueous solution. A suitable concentration is about 5 to 30%. The amount of alkali carbonate used is preferably 2 to 3 times the chemical equivalent of the carboxylic acid contained in a 20% aqueous solution. The cleaning is performed by stirring and mixing the crude tar acid and the aqueous alkali carbonate solution, for example, for several minutes. After washing with the alkali carbonate, it is left to stand and the aqueous aqueous phase of the alkali carbonate is separated. In this case, if a small amount of alkali carbonate and carboxylic acid sodium salt are mixed in the separated tar acid phase, they are separated as non-volatile components by distillation. This distillation may be a simple distillation for removing non-volatile components, but it is advantageous to also remove high-boiling materials such as pitch. When washing with such an alkali carbonate, most of the carboxylic acids can be removed. After depitching, the crude tar acid from which carboxylic acids have been removed is brought into contact with a cation exchange resin to remove base components. At this time, the water content in the crude tar acid is 1%.
Generally, washed crude tar acid must contain more than 10% of tar, unless it is dehydrated by distillation.
% or more, so it is not necessary to add water. Water is removed after treatment with cation exchange resin.
It is removed by dehydration distillation as appropriate. As the cation exchange resin, for example, known ones such as a styrene-dipinylbenzene copolymer type having a sulfonic acid group can be used. For the contact with the cation exchange resin, an efficient method is to flow the crude tar acid through a packed tower filled with the cation exchange resin. The appropriate conditions for circulating and contacting are room temperature LHSV of about 0.2 to 2.
In addition, if multiple cation exchange resin packed columns are prepared and alternately switched to adsorb base components and regenerate with mineral acids such as sulfuric acid, as is usually done, continuous contact can be achieved. Can be done. The crude tar acid that has been contacted with a cation exchange resin and subjected to abasing treatment is then purified by distillation using a conventional method. If oxidizing agent contact equipment is installed before this distillation purification to make the thiol content, which accounts for most of the sulfur compounds, heavier, not only organic acids and tar bases but also sulfur compounds can be significantly reduced. It is possible. As the oxidizing agent, air, hydrogen peroxide, etc. can be used. This distillation converts tar acid into phenol, o-cresol, m-cresol, p-cresol, 2,
It is separated into several fractions such as 6-xylenol, and high boiling point fractions and low boiling point fractions are removed. In the case of batch distillation, the first distillation separates high-boiling components such as pitch and low-boiling components such as water, and the desired fractions are sequentially taken out in the next or subsequent distillations. In addition, in the case of continuous distillation, a dehydration tower, a first distillation tower (de-pitch tower),
Distillation is carried out using several distillation columns depending on the desired fraction, such as a phenol column, an o-cresol column, a meta-cresol column, and a xylenol column. Note that when cation exchange resin treatment is performed between the alkali carbonate cleaning device and the dehydration tower, installation of a new dehydration tower may be omitted. According to the method of the present invention, impurities contained in tar acid, particularly carboxylic acids and tar bases, can be significantly reduced, and it is possible to obtain a product of the same quality as synthetic phenols. Examples of the present invention will be shown below. Example: Coal tar oil is charged into a deoxidizing tower, extracted with a caustic soda aqueous solution, a sodium tar acid aqueous solution is extracted from the bottom of the tower, this sodium tar acid aqueous solution is washed with light oil, and then subjected to steam stripping treatment. The product is charged into a gas decomposition tower and brought into contact with carbon dioxide gas to decompose most of the sodium tar acid, then sulfuric acid is added to this to decompose the remaining sodium tar acid, and then left to stand to separate the tar acid phase. This was used as crude tar acid. Crude tar acid is made by removing moisture in addition to tar acid.
15%, 4% heavy components such as pithu, carboxylic acid
Contains 3619ppm, 1890ppm tar base and 579ppm neutral oil and others. In addition, tar acid is 31% phenol, 45% cresols, and xylenol.
The carboxylic acids mainly consist of carboxylic acids such as formic acid, acetic acid, propionic acid, and benzoic acid, the tar bases mainly consist of pyridine, picoline, aniline, and quinoline, and the neutral oils mainly consist of thiophenol and thiocresol. Consisting of 10 parts of a 20% aqueous sodium carbonate solution was added to 100 parts of this crude tar acid, and the mixture was stirred for 5 minutes for washing.
The pH was 10.1. After washing, let it stand and take out 100 parts of the tar acid phase.
It was charged into a distillation column to remove substances with a high boiling point of 250°C or higher.
The distilled crude tar acid is 90 parts and contains 15% water. This crude tar acid was passed through a cation exchange resin through a packed column at room temperature and LHSV2.0. High porous type DIAIONHPK25 was used as the cation exchange resin. After flowing through the cation exchange resin packed column for about 3 hours, it was regenerated with 10% sulfuric acid and used repeatedly. During this period, the exchange capacity was 0.7 mg/ml-Resin, and the abasification rate could be maintained at 99% or higher. By carrying out this operation, 90 parts of treated tar acid were obtained. Organic acids in this tar acid are 30ppm
Below, tar bases were reduced to less than 10 ppm. After contacting this tar acid with an oxidizing agent of hydrogen peroxide, precision distillation was carried out using a batch distillation column, and the following results were obtained.

[Table] Le

[Table] Rule
Note that when crude tar acid obtained by decomposing sodium tar acid is directly distilled under the same conditions as in the example without washing with soda carbonate and contacting with a cation exchange resin, the following results are obtained.

[Table] Xylenol − − −
Comparative Example It was found that when the crude tar acid obtained in the example was subjected to only depitch distillation without washing with sodium carbonate and passed through a column filled with a cation exchange resin, the debasing function was inhibited. The debasing rate at the beginning of the fluid flow was 85% and worsened as the fluid flow progressed.

Claims (1)

[Scope of Claims] 1. When refining crude tar acid separated from tar oil, coal liquefied oil, coal gasification condensate, etc., carboxylic acids are removed, and then the base impurities are removed by contacting with a cation exchange resin. A method for purifying tar acid, characterized by the following. 2. The method according to claim 1, wherein the method for removing carboxylic acids is washing with an alkali carbonate.