US2642380A - Recovery of waxes from shale oil - Google Patents

Description

June 1953 J. w. HORNE ETAL RECOVERY OF WAXES FROM SHALE OIL Filed July 5, 1951 SOLVENT TANK WASH RECOVERED SOLVENT sou ENT 4 TANK \6 M on SOLVENT FILTRATE v CRUDE-MIXED SOLVENT PARAFFlN-OLEFIN STRIPPING wAx RECEIVING TANK COLUMN T STEAM DEWAXtD OIL- AROMATIC RAFFTNATE l2 STEAM PARAFFlN-OLEFIN ELUANT WAX MELTING TANK SOLVENT TREATING 9 TANK DEODOR- f IZING COLUMN v RECOVERED I SOLVENT STEAM AD- I3 I SORPTION COLUMN WATER CONCENTRATED WAX TXERL COLUMN [0 f AND ELUANT COLUMN COLOR- IZING l4 TowER M FULLY- OLEFIN REFINED coNcENTRATE PARAFFIN REFINE; MIXED OLEFIN WAXES PARAFHMOLEHN TO SUCCEEDING ADSORBERS WAX RECEIVING TANK WATER INVENTORS DRAW-OFF TO WASTE Joseph W. Home AT-TOR N EY Patented June 16, 1953 UNITED sTA RECOVERY OF WAXES'FROM SHALE OIL Joseph W. Horne and Peter R. Tisot, Laramie, Wyo., assignors to the United States of America as represented by the Secretary of the Interior Application July 5, 1951, Serial No. 235,354

8 Claims. (01; 196-18) 7 (Grantedunder Title 35, U. S. Code (1952),

sec. 266) The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of royalties thereon or therefor. v This invention relates to the recovery of olefinic and paraffinic waxes from shale oil.

The occurrence of waxy material in oil produced bythe pyrolitic decomposition of the organic material (kerogen) contained in oil shale is, of course, well known. Up to the present time however, there has been relatively little investigation of these shale oil. waxes, particularly in this country, and ithas long been considered that these-waxes, particularly thoseof higher melting point, are, likei'petroleum waxes, substantially. paraffinic; in character. ,Thus, it has been considered that the same methods employed forthe recovery and purification of petroleum waxes, suchas sweating or solvent extraction followed by acid treatment, would be equally applicable for separation and recovery of shale .oil waxes.

It has beenfound, however, that in contrast to the waxes that may be obtained from petroleum, relatively high melting point waxes More specifically, it has been found v recover the waxy material contained therein and then separating, preferably by selective adsorption, the olefinic'content of the waxy ma-v terial from the paraffinic portion thereof, it is possibleto produce one waxwhich is substan tially, paramnic in nature, and another wax which is highly olefinic. The paraffinic wax produced in this manner willtfind application wherever high grade parafiin waxes are em ployed, such as inthe food packaging industry The. olefinic wax produced inaccordance with the invention is unique in that it is relatively high melting and'of high molecular weight and yet contains a high percentage of olefiniciunsaturation. r

.The crude. oil which forms the source material for the production of waxes in accordance with the invention is .obtainedby the destructive distillation of naturally occurring oil shale at temperatures which usually range from.900 to 1300 F. In conformity with usage in the United States," the term oil shale? in the specification and claims is intended to refer to rate, quantity of wax recovered and the oil .source materials sedimentary rocks containing kerogen, regardless oftheir common or scientific designations,

which upon destructive distillation yield 'a' mixture of hydrocarbons and certain nitrogen and phenolic compounds, usually called shale oil.' Extensive deposits of .oil shale are found throughout the world. The crude oils obtained by'destructive distillation-of domestic oil shale,

particularly of the type found in "Colorado,- Wyoming, and Utah are particularly useful as in connection with the present invention. i

From the crude shale-oila distillation fraction is prepared, hereafter referred to as the wax distillate, boiling between'6'75 and 950 F. and preferably between 750 and 925 F. This wax distillate characteristically contains a high percentage'of nitrogencompounds (in thecase' of Colorado shale oils from to as well as a higher-proportion of aromatic sulfur and oxygen compounds than are found in petroleum crudes. Separation of these nitrogen,

aromatic, sulfur, and oxygen compounds, as. well as the paraffin oils, from the hydrocarbon waxes is accomplished by extracting the wax distillate with a solvent which has strong solvent power for these components, but substantially no 'solventpower for the hydrocarbon waxes at the selected dewaxing temperature. A single solvent may be employed or if desired ablend of solvents. Methyl ethyl ketone used alone ishighly satisfactory from the standpoint of the size and structure of the wax crystalsproduced, quantity of solvent required, filtration content of the wax extracted. A mixture of ethylene, dichloride and acetone is also very satisfactory; Usually the wax distillate and the solvent or blend of solvents, are mixed thoroughly at 'a' temperature sufficienty high to form. r a

homogeneous solution and, then 1 the mixture chilled to crystallize out the wax. However, if

desired, the wax'distillate and solvent may be: chilled separately tothe dewaxing temperature and then thoroughly mixed.

At the dewaxing temperature, 'which preferably is in the range of -0- to 35 FL, dependgen, aromatic, sulfur, and oxygen compounds present in the wax distillate.

The crude wax obtained in this manner is a hydrocarbon wax of relatively high melting point, usually ranging between 90 and 200 F., and in many respects resembles petroleum parafiin wax with the exception that it contains a relatively high percentage of olefinic unsaturation, usually from to 18% by weight. If this mixture of olefinic and parafiinic waxes is refined by acid treatment in the usual manner of refining petroleum parafli n waxes, loss of the entire olefinic content of the wax would result with the consumption of atlarge amount of acid. In accordance with the invention, instead of eliminating the olefin content by such methods as acid treating, the parafiinic and olefinic waxes contained in this mixture are separated from one another, preferably by selective adsorption, to produce two distinct waxes, one a parafiin wax, containing no olefinic imsaturation, and the ther a relatively high melting point wax containing a h h de ree .of olefinic :unsaturation.

he f llow ng example illustrates the recovery of pa a-limit and l finic waxes from a shale oil produced by the destructive distillation of a domestic oil shale. For the purposes of clarity, reference will be made to the accompanying drawing which diagrammatically illustrates the procedure employed in this example. The wax distillate employed as the starting material in this example was obtained by fractionating a crude shale .oil produced by .retorting Colorado oil shale assaying about gallons of crude oil per ton of shale by the so-called N-T-U retorting process. In accordance with this retorting process, crushed shale is loaded into a cylindrical retort and the shale at the top of the retort is then ignited and air is blown downwardly through the shale bed. Heat furnished by comusti n of th upper layer of shale serves to de-' compose the kerogen in the layers of shale beheath the combustion zone. The oil vapors which distill from the shale are carried out in the retort in the ,hot gas stream. The combustion zone advances downwardly through the complete charge in the cylindrical retort, residual carbon in the shale from which the oil has already been driven supporting the combustion and furnishing heat throughout the retorting process. Distillation temperatures are in the neigh rhood of from 850 to 1000 F.

The crude shale oil obtained in this manner was topped to 675 F. at 5.85 mm. of mercury. From the remaining bottoms, the wax distillate was continuously distilled at an overhead temperature of 525 F. (plus or minus 5 F.) at 5 mm. Hg (corresponding to 895 F. at 760 mm. Hg). The wax distillate constituted of the crude oil.

Referring now to the drawing, the wax distillate in storage tank I was mixed in tank 3 with methylethyl ketone from solvent storage tank 2. The ratio of oil to solvent was 1:2 by. volume. The oil-solvent mixture was warmed to efiect complete solution of the crystallized wax, and was then transferred to chilling vessel 4 where it was chilled to 32 F. at the rate of 3 to 5 F. per hour. The wax which separated on cooling consisted of well defined plate crystals.

The mixture was next transferred to a filter 5 where the wax crystals were filtered off and washed with chilled solvent from wash solvent tank 6 to remove the oil adhering thereto. filtrate containing the paramn oils and the The Per cent ,Paraflins and naphthenes 83.3 Olefins 16.7 Aromatics 0.0

If desired, the single solvent extracted wax may be subjected to further solvent extraction to improve the color and further reduce the oil content. However this is not necessary since with a single solvent extraction, the oil content was reduced to within the limits ordinarily required of a fully refined petroleum parafiin wax.

The single solvent extracted wax was trans? ferred to a steam .deodorizer 9 where the crude wax was melted and agitated with wet steam to remove volatile odor-forming impurities. Condensed steam was separated from the wax in settling tank [0. After this treatment, the wax had no objectional odor or taste, had an amber color and contained the olefins present in the solvent extracted wax. This product remained color stable.

. The steam treated wax was next transferred to a decolorizing tower H where it was decolorized by percolation through a bed of an activated bauxite (sold under the trade name Florite') sized to 20-60 mesh. By percolating the wax through the bauxite at to F. (about 15 F. above its melting point) with a contact time of about 5 hours, a water white product was obtained. The finished product was colorless, odorless, and tasteless, and had the following analysis:

. Per cent Paraflins and 'naphthenes 87.4 Olefins 12.6 Aromatics 0.0

As will be noted, some of the olefins were adsorbed on the bauxite, resulting in a lower percentage of olefins in the refined paraffin-olefin wax. The olefins adsorbed during the decolorization treatment may be desorbed from the bauxite by a suitable eluent such as cyclohexanol, and if desired subjected to further purification.

The steam and bauxite-treated wax was then transferred to a melting tank I2 and the melted wax percolated through a tower l2 packed with silica gel adsorbent. Percolation was continued until the adsorption capacity of the silica gel column for the olefinic content of the mixed waxes was reached. Most conveniently, the adsorption capacity of the particular adsorption column forthe particular wax mixture being separated is- During the. initial stages of the desorption V stituents.

paraffin olefin wax from the first or from succeeding adsorption stages may be utilized assuch.

As the desorption proceeded the parafiin-olefin concentrate was succeeded by a fraction consisting of essentially 100% olefins, herein termed a fully refined olefinic wax. This 100% olefin wax was collected separately.

The fully paraifinic and fully olefinic waxes prepared as above hadthe following composition:

Parai finic W ax Percent Percent 100 Parafifins and naphthcucs .i Olefins 0 100 Aromatics i i 0 0 The fully parafiinic wax had a melting point of 100 to 150 F. and met all the specifications required for a fully refined petroleum parafiin wax. The olefinic wax had a melting point of from 100 to 150 F., was water white, was color stable, and had no objectionable odor or taste.

ihe fully, or partially olefinic waxes produced in accordance with the invention are unique'in that they are high molecular weight materials containing a high degree of olefinic unsaturation. Such unsaturated waxes, which may be produced in large quantities from crude shale oil in accordance with the invention, are difficult to produce If desired, however, the concentrated other" than silica'gel may be employed toseparate the'olefins and paraiiin's, although a silica gel adsorbent. is to be preferred for itshigh adsorbent capacity. and adsorbent strength for the olefinic constituents of the wax. :It is to be understood that the above description, together with the specific examples and embodiments described, is intended merely to illustrate the invention, and that the invention is not to be limited thereto, nor in any way except scope of the appended claims.

l. A method for the recovery of paraffinic and olefinic waxes of relatively high melting point from an oil produced by the destructive distillation of oil shale comprising the steps of solvent extracting a distillation fraction of said shale oil by the boiling between 675 and 950 F. to recover the synthetically by such methods as the dehydrogenation of paraffin waxes, since the dehydrogenation treatment usually results in degradation of the wax molecule yielding a wax of lower molecular weight.

The olefin waxes produced in accordance with the invention have a melting point ranging between 90 and 200 F. and contain from 20% and up to 100% The unique properties of these olefinic waxes makes them highly suitable for many applications such as in the production of high melting point halogenated waxes, or as efiicient anti-sun checking agents when compounded with rubber (see copending application gel. No. 247,741 filed September 21, 1951 for Rubber Compound of Improved Resistance to Sun Checking. and Other- Types of Deterioration by Fred W. Staten). Because of their unsaturated nature these waxes can be readily halogenated.

While the above example illustrates a preferred procedure and preferred conditions for the recovery of olefinic and parafmic waxes from crude shale oil, it is to be understood that variations in th procedure outlined are possible within the scope or" the invention. Thus, for example, the mixture of parafiin and olefin waxes obtained by a single solvent extraction of the wax distillate may be immediately separated into its olefinic and para'ffinic constituents without prior treatment to deodorize or decolorize the wax. Similarly solvents and eluents other than those mentioned may be employed. Suitable adsorbents olefins, principally mono-olefins.

waxy material contained therein and then separating the olefinic content of said waxy material from the parafiinic portion thereof to produce one waxy material substantially parafilnic in nature,

and another waxy material containing a substanv tial degree of olefinic unsaturation. V

2. A method in accordance with claim 1 in which methylethyl ketone is employed for said solvent extraction.

3. A method for the recovery of paraffinic and olefinic waxes of relatively high melting point from an oil produced by the destructive distillation of oil shale comprising the steps of solvent extracting a distillation fraction of said shale oil boiling between 675 and 950 F. to recover the waxy materials contained therein, contacting the separated waxy material with an adsorbent material to preferentially adsorb the olefinic portion thereof, followed by desorption of the olefinic portion, to produce one waxy material substantially paraifinic in nature, and another'waxy material containing a substantial degree ofv olefinic unsaturation.

4. A method in accordance with. claim 3 in which methylethyl ketone is employed for said solvent extraction.

5. A method for the recovery of parafiinic and olefinic waxes of relatively high melting point from an oil produced by the destructive distillation of oil shale comprising the steps of mixing a distillation fraction of said shale oil boiling between 675 and 950 F. with a solvent having substantially no solvent power for the hydrocarbon waxes in said fraction and a strong solvent power for the remaining components of said fraction, reducing said mixture to a temperature of from 0 to 35 F. to permit the hydrocarbon waxes contained in said mixture to be separated therefrom,

hydrocarbon waxes from the paraffinic portion thereof to produce one waxy material substantially paraffinic in nature, and another waxy material containing a substantial degree of olefinic unsaturation.

6. A method in accordance with claim 5'in which methylethyl ketone is employed for said solvent extraction. Y

7. A hydrocarbon wax containing at least 20% of olefinic hydrocarbons and having a melting point above F. obtained by solvent extracting 0 a distillation fraction boiling between 675 and 950 F. of a crude oil obtained by the destructive distillation of oil shale to recover the waxy material herein, and then separating at least a portion of the parafilnic content of. said waxy material from the olefinic portion thereof.

8. A hydrocarbon wax consisting of substantially 100% olefinic hydrocarbons and having a melting point above 90 F. obtained by solvent extracting a. distillation fraction boiling between 675 and 950 F. of a crude oil obtained by the destructive distillation of oil shale to recover the waxy material contained therein, and then separating the paraflinio content of said waxy material from the olefinic portion thereof.

JOSEPH W. HORNE.

PETER. R. TISOT.

Name Date Van der Waerden Feb. 1, 1938 Number 8 Number Name Date 2,459,442 Lipkin Jan. 18, 1949 2,543,286 Hirschler Feb. 27, 1951 5 FOREIGN PATENTS Number Country Date 430,485 Great Britain June 19, 1935 OTHER REFERENCES Warth. The Chemistry and Technology of Waxes. pages 7, 9 and 10. (1947). Reinhold Pub. Co.

Claims (2)

1. A METHOD FOR THE RECOVERY OF PARAFFINIC AND OLEFINIC WAXES OF RELATIVELY HIGH MELTING POINT

7. A HYDROCARBN WAX CONTAINING AT LEAST 20% OF OLEFINIC HYDROCARBONS AND HAVING A MELTING POINT ABOVE 90* F. OBTAINED BY SOLVENT EXTRACTING A DISTILLATION FRACTION BOILING BETWEEN 675* AND 950* F. OF A CRUDE OIL OBTAINED BY THE DESTRUCTIVE DISTILLATION OF OIL SHALE TO RECOVER THE WAXY MATERIAL THEREIN, AND THEN SEPARATING AT LEAST A PORTION OF THE PARAFFINIC CONTENT OF SAID WAXYT MATERIAL FROM THE OLEFINIC PORTION THEREOF.

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