US1772921A - Process for purifying hydrocarbon oils - Google Patents

Description

atented Aug. i2, 1930 STATES mo rnnsz, or mnnsnunn, ennmm raocnss non romaine mnocannon one 80 Drawing. Application filed Ju1y,8, .1924, Serial No. 724,792, and in Germany July 18, 1928.

This invention relates to the processes for purifying hydrocarbon oils, such as petroleum, shale oil, brown coal tar oil, pit coal tar oil, and the products obtained therefrom.

5 It is known that hydrocarbon oils which have only been distilled in the manner usual in the art, after some time assume a dark colour and in some cases a disagreeable odour and that there is aformation of resin and a separation of a deposit.

In order to avoid these objectionable phenomena, the oils are, after distillation, subjected to a refining process.

'- Now I have found that these objectionable phenomena are not caused by the hydrocarbons themselves, but by certain com ounds present in these oils and. containing esides carbon and hydrogen, also oxygen, nitrogen and sulfur. Such compounds are especially oxygen-containing bodies, such as furaneand its homologues, and nitrogen-containing bodies, such as pyrrol and its homologues, and derivatives of these-compounds.

In the usual refining processes for instance when refining the hydrocarbons by treatment with sulfuric acid, not only theseobjectionable constituents are acted upon and removed, but also the olefines, though there would be no objection to leaving them in the oil. This,

of course, causes a loss of valuable material, which loss is especially remarkable in the case of oils containing a large percentage of unsaturated constituents, such oils being obtained for instance by destructive distillation of brown coal or lignite and by the known crackingprocesses.

Now, I have further found that the constit-uents, causing the dark coloration or the disagreeable odour or the formation of resins and deposits, have a well defined boiling temperature, depending upon the nature of the oils, and that consequently these constituents can be separated and removed by fractional distillation, if this is very exactly performed.- According to my invention, I proceed in contradiction to the distillation processes usual in the treatment of mineral oils. In-

deed, in distilling mineral oils, it is now usual toseparate the oils into fractions boilinig within relatively large limits, while accor narrow boiling tageous to effect the distillation under reduced ing to my invention, the distillation is performed in apparatus allowing of fractions being obtained which distil over within very limits, the fractions being preferably col ected separately from degree to degree or even less. Such apparatus are for instance known and used in the art ofrectifying alcohol. By applying this method,

it is possible, by separately collecting the products which are distilled within such narrow limits, to ascertain first by a preliminary test, which fractions of the material under treatment contain the objectionable constituents, which fractions may be, termed resin forming fractions. These fractions are removed when distilling the oils in raetice, while the other fractions not containing such constituents may be collected within any convenient limits. It is therefore possible to refine the oils by a simple exact fractional distillation and to avoid" artly orwholly the usual refining probesses y'means of chemical substances and the losses connected there with. As the boiling points of the resin forming substances depend upon the pressure, itis advisable to keep the pressure constant during the distillation.

In certain cases, especially in the case of oils having a high boiling point, it isadvamso pressure, as the boiling points of the, resin orming substances are modified by a change of pressure. Thus, it is possible in many cases to prevent other substances which at a certain pressure would be distilled over at the same temperature as the resin forming. substances, from being removed together with the latter, the boiling point of'such substances being modified in another manner than that of the resin forming substances, if the pressure is changed.

In certain cases it is also possible to a ply reduced pressure only during a part 0 the distillation.

Similar methods can be applied to-the further treatment of the separated resin forming fractions.

In certain cases the urification can be ob tained more rapidly, y first formin fractions boiling within somewhat larger imits, 10

comprising morethan one degree, and then removing the resin forming constituents by subjecting these fractions to a further exact fractional distillation as described.

The raw materials can either be immediately treated as described, or first be subjected to a slight preliminary refining treatgravity, is distilled by means of a rectifyin ment as usual in the art of treating petro- Ewampl'es 1. Benzine, obtained by destructive distillation of brown coal and having 0,780 specific apparatus provided with an efficient dephlegmator, and the distilled products are separately collected fromdegree to degree. It is found that the fractions distilling over at 62, 86 and 108 C. contain colouring, resin form ing and deposit forming eonstltuents, while theother fractions do not contain such substances. It is therefore possible to obtain a pure product, not .c'ontamin objectionable constituents by simply distilling the said oil and removing the fractions above referred to. Other starting materials can be treated in an analogous manner. 2. When distilling a brown coal benzijne having a resin forming fraction boiling'at 138 C. and containing a remarkable percentage of xylols, most 'of these xylols is distilled over together with the said resin forming fraction. If, however, the distillation is effected under reduced pressure, for

' loss of xylol-being avoided.

. fractions, which have been separated, can be 3. In thecase referred to in Example 2 it is also possible to perform the distillation first at ordinary pressure, the pressure being kept constant until a temperature of 125 C. is reached, and then to apply reduced pressure. By proceeding in this manner, the

boiling oint of the res1n forming fractions is modi ed in another manner than that of the hydrocarbons boiling at'theisame temperature at ordinary pressure, and the same result is obtained .as in Example 2. a

In a similar manner the resin forming further treated.

at I claim is 1. The process for purifying hydrocarbon oils, which com rises separating a test portion from the oil distilling said portion and collecting therefrom fractions within narrow limits to determine the boiling temperatures of fractions forming resins and deposits and causing coloration and disagreeable odors, then distilling the main body of the oil fractionally and at the ascertained temperatures, and separating such fractions from the remainder of the oil. 7

. 2. The process for purifying hydrocarbon oils contalning a large percentage of unsaturated hydrocarbons and olefines, which comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine the boiling temperatures of fractions forming resins and deposits and causing colg oration and disagreeable odors, 'then distilling the main body of the oil 'fractionally and without substantial loss of olefines and at the ascertained temperatures, and separating such fractions from the remainder of the oil.

3. The process for purifying hydrocarbon oils, which comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine the. boiling temperatures of fractions forming resins and deposits and causing coloration and disagreeable odors,

then distilling the main body of the oil fractionally and at the ascertained temperatures, and separating and discarding such fractions from the remainder of the oil.

4. The process for purifying hydrocarbon oils, which comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine the boiling temperatures of fractions forming resins and deposits and causing coloration and disagreeable odors, then distilling the main body of the oil fractionallv and at the ascertained temperatures, separating such fractions from the remainder of the oil, and completing the fractional distillation of the oil. and blending said fractions.

5. The process for purifying hydrocarbon oils, which comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine the boiling temperatures pf fractions forming resins and deposits and causing coloration and disagreeable odors, then distilling under constant pressure the main body of the oil fractionally and at the ascertained temperatures, and separating such fractions from the remainder of the oil.

6. 'The process for purifying hydrocarbon oils, which comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine theboiling temperatures of fractions forming resins and deposits and causing coloration and disagreeable odors, then distilling under reduced constant pressure the main body of the oil fractionally and at the ascertained temperatures, and separatcausing l 0 ing such fractions from the remainder of the o1 7. The rocess for purifying hydrocarbon oils, whic comprises separating a test portion from the oil, distilling said portion and collecting therefrom fractions within narrow limits to determine the boiling temperatures of fractions forming resins and degosits and coloration and disagreea 1e odors,

then distillingthe main body of the oil fractionally', distllling the separated fractions under reduced constant pressure and at the ascertained temperatures, and separatmg such fractions from the remainder of the oil.

In testimony vi -hereof I have afiixed my ,JENo mn's z.