US2055486A - Process for preparing resins and asphaltenes - Google Patents

Description

Sept. 29, 1936. 5. FULTON 2,055,486

PROCESS FOR PREPARING RESINS AND ASPHALTENES Filed Oct. 30, 1951 Ptenteoi Sept. 29, 193

PROCESS FOR PREPARING RESINS AND ASPHALTENES Stewart 0. Fulton, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application October 30, 1931, Serial No. 572,059

6 Claims.

This invention relates to a process for preparing resins from heavy petroleum products, especially cracked tar of petroleum origin, and to the product of this process. The invention will be understood from the following description read in conjunction with the drawing, the sole figure of which is a diagrammatic side elevation, partly in section, of a suitable apparatus for carrying out the process.

According to this invention, resins having novel and valuable properties are segregated from oily materials containing the resins. An important step in the process is based on my discovery that in cracked tars of petroleum origin the oil next to the resin fraction has low boiling point for a given viscosity and can be fairly completely separated by distillation from the resin fraction. Certain other heavy petroleum products such as topped crudes show a similar behavior, although in asphaltic base residues prepared by non-cracking distillation, such as those obtained from Colombia or Panuco crudes, the oil is usually too high boiling to be separated from the resin by distillation.

The raw material preferably used in my' process is a tar obtained by liquid phase or vapor phase cracking of petroleum hydrocarbons or more generally any residual petroleum product in which the oil can be fairly completely separated from the resin fraction by distillation. Tars obtained by extensive cracking of petroleum products un-- der 2, pressure of 350 pounds per square inch or higher are the best raw material for my process.

The tar, which usually has low gravity, sayl-11 A. P. I. is first subjected to a distillation to remove most of the oily constituents. The distillation is preferably carried out under vacuum with or without the admission of steam or other gaseous agent to help the distillation. However, the tar may also be reduced by fire and steam under atmospheric pressure. When distilling in a vacuum of 1 mm. the distillation may be carried out up to about 660 F. still temperature whereby the greatest part of the oily products are removed overhead and a residue having a softening point of approximately 240 F. is obtained as determined by the ball and ring method.

Final boiling pointnu The residue is then agitated with a solvent for resins, for example a light hydrocarbon oil such as kerosene, heavy or light naphtha. The volatile petroleum distillate known in the trade as Varsol is suitable: for this purpose. This has the following specifications:

Color +22 Per cent off at 350 F 55% minimum Per cent off at 392 F 410 F. Abel flash 100 F. Passes doctor test about three times the volume of the residue and 95% minimum the agitation is preferably carried out while the residue is still hot, say around 200 F. If a light naphtha is used then the agitation is preferably carried out under pressure. The agitation may be replaced by a refluxing operation carried out at about the boiling point of the solvent. The mixture of residue and solvent is then cooled to approximately room temperature and settled or filtered, whereby most of the asphaltenes are removed as the residue of settling or filtration. They may be further purified as will be described later. The solution contains the resins and some asphaltenes together with some highly unsaturated unstable material. This solution is then acid treated with sulfuric acid of say 95% concentration, although more diluted acid or more concentrated acid, even fuming sulfuric acid, may be used. The amount of acid required is determined by the color of the final resin product. If a light color is sought more acid is used while with a darker colored resin less acid will be required. For an average resin product the amount of acid is about 20% by weight based on the material dissolved in the solvent although this amount may be greatly varied, say between the limits of 5%-50%.

The sludge formed by the acid treatment is separated by filtration or by settling and decantation, the time of settling being one-half hour or longer. The residual acid in the solution may be removed either by contacting with clay or by water washing or by washing with dilute caustic soda. The preferred method for removing the acid is contacting with clay, which may be carried out at room temperature using a finely powdered clay such as Attapulgus fines or an acid treated clay.

' tank 5.

easily determined by experiment.

After the'acid treatment and the removal of sludge and acid, the solution containing the resin is reduced by distillation which may be carried out either under vacuum or at atmosphericpressure, with or without steam or other distillation aid. The residue of the distillation is the final resin product with a yield usually varying between 5' and 9% by weight on the amount of 10-1 1 A. P. I. gravity tar used. In many cases it is not necessary to separate the solvent from the resin but the light hydrocarbon solution of the resin is used. In other cases the light hydrocarbon solvent is only partially removed so as to obtain a concentrated resin solution.

The asphaltene residue above referred to may be further purified by washing with the light hydrocarbon solvent such as Varsol to remove substantially all the resins. I prefer to carry out this washing operation countercurrently, either continuously or in batch operations. The solvent from the washing operation can be used in the original extraction of the reduced residue and serve as a vehicle to carry the resins through subsequent operations. The purified asphaltenes may be used for various purposes.

My process may be varied in such manner that the acid treatment and the neutralizing steps become superfluous. By the employment of special selective solvents the expense of these refining steps may be avoided insome cases. If the first distillation residue containing asphaltenes and resin and freed from oily products is treated with a light paraffinic hydrocarbon solvent such as petroleum ether, liquefied butane or pentane, either alone or in mixtures, instead of the Varsol, then a sufliciently pure resin solution is obtained so that the sulfuric acid treatment becomes unnecessary. The treatment may consist in heating the residue with the paraflinic hydrocarbon under atmospheric or higher pressure, or in dissolving the residue in a small quantity of a solvent such as ethylene dichloride, benzol, etc., and precipitating the asphaltenes from the solution by the addition of the low boiling paraflinic hydrocarbon (petroleum ether, liquefied butane or pentane) If a somewhat heavier parafiinic hydrocarbon such as light petroleum naphtha is used as solvent for the resin, a light acidtreat may be required. The resin solution is' finally subjected to distillation if a sold resin is wanted.

The apparatus used in the process will now be briefly described:

The cracked tar is charged through line i to vacuum still 2 provided with an overhead vapor line 3 which leads into a condenser (not shown) and a valved line 4 to transfer the residue into a Extractor 6 is connected by pipes 5a and 1a with tank 5 and the light hydrocarbon solvent tank 1 respectively. The extractor has an agitator 8 and a cooled line 9 to return reflux to the same. The extract is passed through line ill by means of pump II to the filter press [2 and the residue in the press may be washed with further amounts of light solvent introduced through line I211. The additional extract obtained in this washing operation can be returned to tank I through lines 13 and M. The residue in the filter press is largely asphaltenes and may be removed for any desired utilization. The clear solution leaving the filter press is collected in tank l4 and then passed to the acid treater l5. After agitation and removal of the acid sludge through line It the treated solution is transferred The amount of clay necessary for acid removal is by pump I! to the clay treater l8, to filter press l9, and'thence to tank 20. The resin solution stored in tank 20 may be used either as such or may be transferred into still 2| in which light hydrocarbon solvent is distilled overhead, condensed in condenser 22 and returned through line Hi to tank I. The residual resin is drawn off through line 23 into a storage tank, not shown.

The resins obtained by my process have hydrocarbon character and are therefore unsaponifiable. Their oxygen content is minimal. In the case of a tar obtained by cracking gas oil the resin content has entirely been produced during the cracking. Polymerization of highly unsaturated hydrocarbons during the cracking appears to be mostly responsible for the production of resins. In the case of a tar obtained by cracking reduced crude the resin content is due partly to the cracking and partly to the original resin content of the reduced crude.

The resins of the present invention are unsaponifiable and show the following inspection data Softening poin (ball and ring method) higher than F.

Color yellow to reddish brown Streak on porcelain yellow to reddish brown Odor none Taste none Solubility-Soluble in Light naphtha, gasoline, etc.,

Linseed oil China-wood oil Esters, such as amyl acetate Benzol Insoluble in Water Lower alcohols alcohol) Acetone Partially compatible with nitrocellulose.

'(e. g. methyl, ethyl, isopropyl homogeneous solution and, whenallowed to dry,

leaves a clear homogeneous film free from tur bidity. Most of the resins made by this invention 1 are partially compatible, which means that they are only compatible when a maximum percentage of the resin in the mixture is not exceeded, this maximum percentage depending upon the solvent or solvent mixture and also on whether or not plasticizers, such as castor oil, dibutyl phthalate, linseed oil, etc., are present. Altering the solvent mixture or using other plasticizer will materially change the proportions in which the resins and nitrocellulose are compatible. In general, my resins are more compatible than coumar.

The following examples will illustrate my prooess:

Example 1 1,000 gallons of I cracking coal tar, gravity 10 A. P. I. was distilled under vacuum to a still temperature of 660 F. leaving 1,334 pounds of bottoms, softening point 225 F. (ball and ring method). The bottoms were taken up in 508 gallons of kerosene distillate or (Varsol) in two 7 hot extractions with agitation (391 gallons for first extraction and 127 gallons for extracting the residue). In this way 1,000 pounds of the bottoms were found to be soluble in the Varsol leaving 334 pounds of insoluble asphaltenes. 200 pounds of 66 B. sulfuric acid was added to the Varsolf solution with agitation the agitation being continued for 15 minutes. After settling, the granular sludge was removed by decantation and filtration, and the Varsol solution agitated with pounds of Attapulgus fines for 15 minutes. The Varsol solution was then filtered to remove the clay and distilled to separate the Varsol from the resin yielding 584 pounds of resin, softening point 193 F. (ball and ring method).

Example 2 1,334 pounds of bottoms from the same tar as above were extracted with Varsol in the same way as in Example 1. pounds of 66 B. sulfuric acid was used in the treat which after removal of the sludge was followed by treatment with 80 pounds of Attapulgus fines. The Varsol solution was then filtered and distilled to isolate the resins, yielding 759 pounds of resin, softening point 194 F. (ball and ring method) free from asphaltenes but much darker than the resin of Example 1.

My invention is not to be limited by any theory nor by the details given in the description of the process for the purpose of illustrating the same but only by the following claims in which it is my intention to claim all novelty inherent in the invention.

I claim:

1. Process for preparing a resin from a tar obtained by cracking a petroleum oil at a pressure above about 350 pounds per square inch, which comprises subjecting the tar to distillation to remove substantially completely the-oily components and to obtain a residue containing asphaltenes and resin and separating a resin having a softening point above F. from the asphaltenes in said residue by means of a selective solvent.

2. Process for preparing a resin solution from a cracked tar of petroleum origin which comprises distilling the tar under reduced pressure to an end point corresponding to 662 F. or higher at about 1 mm. mercury pressure, agitating the residue with a resin solvent, separating the resin solution from the insoluble material by filtration,

contacting 'the solution with from. 5 to 50% of 66 B. sulfuric acid, separating the sludge formed thereby by filtration, and neutralizing the remaining resin solution with alkali or clay.

3. Process according to claim 1 in which said petroleum oil is a gas oil fraction containing no resin.

4. Process according to claim 2 in which the undissolved material after extraction with the resin solvent is purified for the purpose of obtaining asphaltenes by washing with fresh petroleum naphtha to remove resinous products therefrom and the resulting naphtha solution is employed for treating the first mentioned distillation residue.

5. Process according to claim 2 in which the acid treated and neutralized solution is subjected to distillation to remove the resin solvent as overhead product and to obtain the said resin as residue.

6. Process for preparing a resin from a tar obtained by cracking a petroleum oil at a pressure above about 350 pounds per square inch, which comprises subjecting the tar to distillation to remove the oily components and obtain a residue containing asphaltenes and resin and substantially free from oily components, dissolving the residue in a small quantity of a solvent able to dissolve both asphaltenes and resin, precipitating the asphaltenes by the addition of a low boiling paramnic hydrocarbon, and separating the precipitated asphaltenes from theresin.

STEWART C. FULTON.

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