CS203364B1 - Process for the cleavage of phenols at the compressive gasification of lignite - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the digestion of phenols under pressure gasification of brown coal, while detoxifying the generator gas.

The hitherto used method of pressure gasification of brown coal in pressure gas works consists in passing the raw generator gas from the generator through a direct and indirect cooler and waste heat boilers to a pressurized gas purification plant using methanol. Alternatively, a detoxification unit is interposed between the waste heat boilers and the respective pressurized gas scrubber, but only to reduce the carbon monoxide content of the gas.

Liquid condensates from direct and indirect coolers and waste heat boilers are distributed in unpressurized large-capacity tar and water tanks. Since phenols are dissolved in the water layer, it is necessary to remove phenols from the water before it is discharged into the public watercourse.

If the detoxification unit is involved in the production cycle, the purification of the phenolic water coming from the detoxification unit is carried out together with the pressurized separation water. However, the nature of the phenol composition in the water from the detoxification is different from the water from the non-pressurized separation, which is caused by side catalytic reactions on the catalyst beds in the detoxification unit.

The currently known methods for recovering phenols from phenolic waste water are based on any of these four methods; namely: adsorption, steam distillation or extraction and distillation.

In extraction of phenols from phenolic waste water from pressure gasification of brown coal extraction methods were used most. Isobutyl acetate and 2-pentanone,

After the extraction, the phenols are separated from the extracting agent by distillation. A polycomponent mixture of monobasic and dibasic phenols with a wide range of boiling points is obtained, which is shipped from the pressurized gasworks for further processing as a phenol concentrate.

The most desirable substances of the phenol concentrate are monohydric phenols with a boiling point of up to 210 ° C, i.e. phenol, cresols and some xylenols. Depending on the phenol content boiling up to 210 ° C, a price evaluation of the phenol concentrate is also carried out. Less desirable substances in fe203364 '203364 nole concentrate are today. monohydric phenols boiling above 210 ° C, dibasic phenols, naphthols and indanols.

The purpose of the invention is to increase the content of monohydric phenols by boiling up to 210 ° C and at the same time to reduce the phenol content boiling above 210 ° C in the phenol condensate.

This is achieved by the phenol cleavage process of the present invention under pressure gasification of brown coal, while detoxifying the generator gas. It is based on the fact that phenols, preferably taken from a waste water desalinator, are injected into a reactor flowing through the generator gas and filled with a conversion cobaltomolybdenum catalyst, the temperature of the reaction bed being 400 to 450 ° C.

Thus, the basic effect of the process of the invention is to increase the content of monohydric phenols boiling up to 210 ° C and to reduce the phenol content boiling above 210 ° C.

Another effect is the formation of aromatic hydrocarbons containing 6 to 8 carbons from the split phenols, which will be entrained from the detoxifier by the converted gas and captured in a pressurized gas scrubber using methanol. At the same time, they will increase the production of gasoline from the pressurized gas scrubber using methanol, and since the most desirable components of this gasoline are aromatic hydrocarbons containing from 6 to 8 carbons, it will also improve its quality.

The process according to the invention also produces hydrocarbons containing from 1 to 4 carbons during the cleavage of phenols, which are transferred to the pressurized gas, whereby a partial increase in the gas production, in particular its calorific value, is also achieved. The process according to the invention and its effects are explained in more detail by way of example.

Example. The phenol fraction of brown coal generator tar was injected at 0.6 ml / min into a reactor (20 ml) filled with a 4 mm cobalt-molybdenum grain conversion catalyst. The carrier gas flow rate was 20 ml / min. The composition of the carrier gas was as follows: 40 vol% hydrogen, 59.75 vol% nitrogen and 0.25 vol% hydrogen sulfide. The temperature of the reaction bed was 420 ° C. The liquid cleavage products formed 90.5% by weight. unsprayed amount.

The contents of selected substances before injection and after passing through the reactor are as follows:

Substance before injection after injection

arom. hydrocarbons Cg - Cg - 3.88 feno 1 0.85 2.90 2-methylphenol 1.19 2.00 3- + 4-methylphenol 9.61 10.68 2,3-dimethylphenol 2.78 1, 78 3-n- + 4-n-propylphenol + 3-ethyl-5-methyl- tylphenol + 2,3,6-trimethylphenol 11, 54 10.51 4-ethyl-2-methyl phenol 5.14 4.71 3,4,5-trimethylphenol + 3-n- + 4-n-butyl- phenol + 2-ethyl-4,5-dimethylphenol + 4-indanol 5.98 4.23

Claims (1)

SUBJECT OF THE INVENTION A process for the digestion of phenols by pressure gasification of lignite and at the same time detoxifying the generator gas, characterized in that the phenols, preferably taken from the waste water de-gasification plant, are injected into a reactor flowing through the generator gas and filled with a cobaltomolybdenum conversion catalyst. to 450 ° C.