DE713750C - Process for the separation of paraffin from brown coal distillation products - Google Patents

Description

Process for the separation of paraffin from coal distillation products The invention relates to a method for separating paraffin from brown coal distillation products by mixing with liquid sulfur dioxide at -ro ° or a lower temperature or by cooling a mixture of brown coal tars or tar oils and sulfur dioxide to -1a ° or a lower temperature and subsequent separation of the deposited Paraffins, It is known from brown coal tar tars or the paraffin-containing ones Lignite tar fractions to precipitate paraffin using liquid sulfur dioxide. and -Although at about + z5 °, and then filter off the paraffin. This method is based on the knowledge that the liquid tar components in the presence of sulfur dioxide by the copious amounts of aromatic hydrocarbons which are contained in the simmering tears are present, are kept in solution at room temperature and contain only paraffin separates.

It was also known to post paraffin-containing lignite tar distillates Separation of the oxygen-containing compounds with liquid sulfur dioxide Mix and cool on -zo to -1S °. Two layers of which the upper in addition to liquid, insoluble in sulfur dioxide fractions the Contains paraffin. As a filtration of such a system proposed there was not possible, the two layers must be as in the treatment of Mineral oil distillates finite liquid sulfur dioxide separated by settling and the dewaxing of the raffinate must be carried out by filtration in another Operations are carried out. Lm out the paraffin from mineral oils at low temperatures To be able to separate homogeneous solution by filtration, they have recently been used Solubilizer. like benzene and his idolnologists, too, which stratification in the liquid Prevent the oil phase. This process has in the tar industry from ver. divorced Reasons did not apply.

It has now been found that tars or tar oils, which have a high, have a creosote content of at least 2%, preferably over 30 "to, even without the presence or addition of solubilizers of the type mentioned by means of sulfur dioxide dewax at low temperatures to obtain deeply stubborn filtrates can. Compared to the above-mentioned method, which also works at - io to - 15 ° In the new way of working, there is no need for pre-decreosotation, which means that a Simplification and also the special advantage of separability of the smoldering tar or smoldering earth distillates obtained from the separated paraffin by filtration will.

According to the invention, the starting materials with ioo to 4ooVolumpro, cent mixed with liquid sulfur dioxide, the mixture is cooled to about -io ° or lower and filtered. The paraffin separates out in a form that is extremely easy to filter, and one arrives at a filtrate, which despite the removal of the solvent the high creosote gel altes one close to the filtration temperature, in many Cases even has pour point well below it and therefore needs to be worked up is ideally suited to diesel oils, lubricating oils and easily flowable heating oils. That The paraffin obtained is freed from the oil that is still adhering to it by washing it out.

It is often advisable to carry out the de-oiling in two stages, in such a way that it is first washed with sulfur dioxide, and then that stubborn stuck oil with a mixture of sulfur dioxide and solubilizers, like benzene. to remove. When using suitable amounts of solvent and setting a suitable solvent concentration in the second stage is then used in this a creosote-free oil obtained.

In many cases, the tars being treated are not rich in creosote to be able to treat them according to the invention. You then increase their creosote content, z. E. Simply by being finite your liquid before or during the mixture Sulfur dioxide adds creosote.

But one can also proceed in such a way that one starts with the starting material at higher temperatures. # z. B. at: Io °, treated with liquid sulfur dioxide, stratification occurs because of the low creosote gel. The top layer contains the saturated hydrocarbons and consists largely of paraffin. In the lower layer, the extract sang, is besides those that remained in solution Hydrocarbons `% 4-.ä. contain all of the creosote. This solution can now can be readily cooled without stratification occurring. With - in "or The entire paraffin present in the extract solution is deposited more deeply. Appropriate «Then ground the raffinate and the satchel obtained from the extract solution together processed further, be it in a further cleaning process, be it for the purpose of recovery of the solvent it contains.

The removal of the solvent from the present process obtained decomposition products is preferably carried out in several stages with decreasing Pressure. This known mode of operation has the particular advantage that in the evaporation of the last traces of the solvent, higher temperatures can be avoided which easily lead to undesirable reactions with tars.

The present method therefore shows a way to obtain Driving. Lubricating and heating oils from lignite distillation products. The for this Previously proposed methods could not find their way into technology. there it was not possible to economically remove the paraffin to such an extent that that filtrate oils with sufficiently low pour points were obtained. In addition the dewaxing agents used since then for dewaxing at lower temperatures, such as acetone, ethyl alcohol, at higher temperatures from the separation products obtained, Sludge and oil, separated "earth, measured, with no attack on the tar oils could be avoided. A considerable part of the raw tar or that for the purpose of separation of paraffin-pressed tar was therefore by hydrogenation and / or pressure cracking processed on low-viscosity oils.

Example i A brown coal tar topped up to about 2 ° with a creosote content of 38 ° j "was mixed with Sao volumetric liquid sulfur dioxide and the mixture was cooled to -i 2 '=. The paraffin which separated out was separated off from the tar solution by means of a filter and removed .loo percent by volume of liquid sulfur dioxide washed afterwards. After removing the solvent from sludge and filtrate, end products were obtained with the properties given in the table below: Output slack (filtrate tar Yield ....... - 18.6 814 Density at 2o'- '. . i, oi8 - 1.037 Pour point ..... + 35 ' - - 25 @' Paraffin content according to Holde ... 10.5 560io - Freezing point - 52. '---- Creosote content Volume percentage .. 380: `0 - - . Example 2 The same tar; which was also used in the above example, was dewaxed in a semi-industrial process at -i2 ° using sulfur dioxide, but in this case only 200 percent by volume of solvent was added to the starting material and the sludge was washed thoroughly. The results are shown in the table below: Gatsch filtrate Yield ................ 17.4 82.6 Density at 2o '... ... . . . . . - 1.054 - - 6o ° ............ o, 870 - Pour point .............. - -210 Paraffin content according to Holde 37.7 - Freezing point. . . . . . . . . 5o, 5 '- "Example 3 A lignite tar stagnating at 39 ° with a Holde paraffin content of ig. 80/0 and a creosote content of 16.50% was extracted at -f- 45 ° with zoo volume percent liquid sulfur dioxide and the resulting raffinate layer was separated and blown The solvent-free raffinate, which was obtained in an amount of 31.2 percent by weight, had a freezing point of 45 ° and a paraffin content of 47: 2 '/ 0.

When cooling the extract solution, the 240j0 creosote, based on the extract, contained, paraffin was deposited at -15 ° and this by filtration separated from the extract solution. The filter cake was made with 100 percent by volume sulfur dioxide rewashed. The collected filtrates were freed from the solvent and white then a pour point of -17 °. The amount was 45 percent by weight by weight on the exit tar. The raffinate and the Slack obtained on cooling the extract solution were combined and mixed with Zoo percent by volume sulfur dioxide diluted; the mixture was filtered and added to zoo Volume percent sulfur dioxide washed. It was a slack wax with 76.5 010 paraffin content and a freezing point of 54 °.

Example 4 A lignite tar obtained by pressurized gasification was used distilled to a residue of II.5 @ 0/0. The distillate obtained with a Creosote content of 36 percent by volume, a paraffin content according to Holde of 4.1 percent by weight and a pour point of 29 ° was mixed with Zoo percent sulfur dioxide and the mixture cooled to -2o °. Stratification did not occur. The solution was filtered for the purpose of separating off the paraffin, the slack wax was taken up with gasoline and de-oiled by filtration at -25 °. After removing the solvent from the Gatsch, the paraffin was obtained in a yield of 6.82 percent by weight.

The filtrates were after removal of the solvents contained therein (Sulfur dioxide on the one hand, gasoline on the other hand) mixed. The mixture had one Pour point of -2i °.

Claims (2)

PATENT CLAIMS: i. Process for the separation of paraffin from lignite distillation products by mixing with liquid sulfur dioxide at -io ° or a lower temperature and subsequent separation of the deposited paraffin by filtration, characterized in that lignite tar or tar oils in the presence of a creosote amount of at least 2o '/ 0, preferably of more than 30 '/ " are treated with amounts of sulfur dioxide between 100 and 400 percent by volume, both based on the tar to be separated. 2. Modification of the method according to claim i, characterized in that from lignite tars that contain less than 2o0 /, creosote, initially by a selective treatment with sulfur dioxide known per se at ordinary temperature A creosote-rich extract solution is prepared, then set to -1O ° or lower cooled and separated from deposited paraffin by filtration.