US2241393A - Process of treating hydrocarbons - Google Patents

Description

May 13, 1941. P. s. DANNER PROCESS OF TREATING HYDROCARBONS Filed March 14, 1958 2 Sheets-Sheet 1 Ph/Y/p 5. Dan/76f INVENTOR ATTORNEY Olefine May 13, 1941. P. s. DANNER 2,241,393 PROCESS OF TREATING HYDROCARBONS Filed March 14, 1938 2 Sheets-Sheet 2 v foraq Polqmers Di-ISObUhJIBHE Toraqe 33 Pmp 3 pan/76k VENTOR ATTORNEY Patented May 13, 1941 I 2,241.39: raocass or resume maocaaaons ramp 5. Banner, Berkeley, Calif., assignor to Standard Oil Company of California, San Francisco, Calii., a corporation of Delaware Application March 14, 1938, Serial No. 195,860

8 Claims.

This invention relates to a new and improved for producing high octane paraflinic motor fuels and highly aromatic petroleum fractions.

Another object of the invention is to provide a combination process in which a mixture of oleflne polymers and a naphthenic petroleum fraction is passed through a series of alternate extraction and hydrogenation-dehydrogenation zones, the vapors from each hydrogenationdehydrogenation zone supplying the heat necessary in a vapor phase selective solvent extraction zone, and the quenching of the vapors in the selective solvent, together with the selective removal of reaction products, serving to halt undesirable side reactions such as polymerization.

An additional object is to provide a; process for catalytically treating olefine polymers in which catalyst poisoning is minimized by vapor phase solvent extraction of a petroleum fraction prior to and/or subsequent to admission in each catalytic zone.

' A further object of the invention is to selectively remove desired reaction products from the reaction mixture-as it flows froma' hydrogenation-dehydrogenation zone,- thereby enabling the desired reactions to be carried further than .would otherwise be feasible and minimizing side reactions. .Another object is to provide a process in which reaction products of olefine polymers and naphthenes are quenched in a liquid phase selective solvent and undesirable side reactions are thereby stopped. V

Figure I is a diagrammatic flow sheet illustrating a process utilizing two catalytic hydrogenation-dehydrogenation zones and a single vapor phase selective solvent extraction zone. Figure 11 illustrates a multi-stage process in which olefine polymers and highly naphthenic petroleum fractions are reacted in a series of hydrogenation-dehydrogenation zonesv and the reaction mixture from each zone extracted with a selective solvent prior to treatment of unreacted portions thereof insubsequent catalytic treating zones.

, the upwardly flowing hydrocarbon vapors.

In Figure I, a petroleum fraction flows through valve l and an oleflne polymer through valve 2 by way of mixing valve 3 to catalytic chamber 4. The mixture of hydrocarbons is treated in catalytic chamber 4 to simultaneously convert the olefine polymers to paraflins by hydrogenation and the naphthenic hydrocarbons therein to aro- -matic and/or cyclic oleflne compounds by (18- hydrogenation. The reaction-mixture from the catalytic treatment is immediately passed from. chamber 4 through line ,5 into extraction tower 6 where the mixture is quenched in a high boiling' selective solvent of the type hereinafter more particularly disclosed. The selective solvent in extraction tower 6 is preferably maintained at a temperature above the initial boiling point of the hydrogenated olefines formed by the catalytic treatment,,but is preferably no more than F. above the dew point of the unconverted naphthenes under the conditions existing in the extraction tower. quenched vapors in tower 6 serves to selectively vaporize the hydrogenated olefines and other paratflns of the same boiling range from the mixture of hydrocarbons in the presence of the selective solvent. Also, the immediate quenching of the reaction mixture in tower 6 inhibits undesirable side reactions which may normally occur at the higher temperatures involved in the catalytic treating zone.

The high boiling selective solvent, which is admitted to tower 6 by line "I, flows downwardly in liquid phase selectively extracting aromatic, naphthenic and unsaturated compounds from A simultaneous liquid phase selective solvent extraction and a fractional distillation eil'ect serves to give an eflicient separation of the hydrogenated olefine polymers from the non-paraflinic constituents of the reaction mixture. The hydrogenated olefine polymers may comprise high octane compounds, and a high octane motor fuel may thus be removed from the top of tower 6 and passed in vapor phase through'iine 8 to condenser and valve controlled line id to storage. A valve controlled reflux line H is provided for returning a portion of the overhead to the top of extraction tower 6.

The downwardly flowing selective solvent, together with its dissolved aromatic, naphthenic and unsaturated compounds, is removed from the bottom of the tower through line II to vaporizer It. A controlled portion of the dissolved hydrocarbons is vaporized in heater l3 and flows through conduit It either by way of The heat released by the tially retain the aromatic hydrocarbons in the selective solvent. By so doing, a highly naph thenic vapor which may also contain olefine polymers is obtained and may be admitted to chamber |1. Olefine polymers or naphthenes or both, as may be required, are admitted through valve controlled line I8, and the mixture of naphthenes and olefine polymers converted to a mixture of high octane paramns and aromatic hydrocarbons by the simultaneous hydrogenation of the olefine polymers and dehydrogenation of the naphthenes in the same manner as in catalyst chamber 4. The neaction mixture from chamber |1 flows through line l9 back to tower 6. where the mixture is quenched and extracted by the selective solvent.

The selective solvent in vaporizer l3, together with the remaining dissolved compounds, flows through line to still 2| where the dissolved hydrocarbons are distilled from the solvent and pass by way of line 22 through condenser 23 to storage. Insome cases the entire olefine content is not hydrogenated in catalyst chambers 4 and I1. Where the proportion 01' such-olefines in the mixture from still 2| is large, it is often desirable to separate these olefines by a suitable fractionating column, e. g. of the same type as tower 6, and a valve controlled line 24 is provided for passing the vapors from still 2| to such an extraction tower rather than to storage. The olefines obtained fro-m this separation may be returned to catalyst chamber 4 or H for the hydrogenation--' dehydrogenation treatment.

As previously indicated, the extract fraction obtained by the above process from still 2| is highly aromatic in composition and comprises an excellent solvent for coating compositions or may be used as a blending agent in motor fuels to increase the octane number thereof. The undissolved vapor phase fraction obtained from extraction tower 6 constitutes a high octane motor fuel when dimers of normally gaseous olefines, such as butene, isobutene dimers and copolymers of the butenes, comprise the olefines fed. into the system, and this fraction is useful as an aviation fuel or wherever high octane paraflinic compounds are desired. Thus the process produces simultaneously a highly paracflinic high octane motor fuel which may contain a large proportion of iso-octane and a highly aromatic hydrocarbon fraction of greater economic value than the original petroleum.

In the modified form of the process illustrated by the flow diagram in Figure 11, a petroleum fraction flOWz, from storage through line and heater 3|, where it is converted to vapor phase, into extraction tower 32. A high boiling selective solvent is admitted to the top of this tower from line 33 and flows downwardly countercurrent l'y extracting the petroleum vapors and simultaneously fractionating the same. By proper control of conditions in tower 32 a major proportion oftheparafllnic hydrocarbons originally present in the petroleum may be selectively vaporized and passed through line 34 and condenser 35 to storage. The selective solvent, together with extracted hydrocarbons dissolved therein, flows from the bottom of tower 32 by way of conduit 36 to still 31. Valve controlled pipe 38 is provided for supplying vapors from still 31 to the bottom of tower 32 for maintaining the temperature in said tower at the required level.

Hydrocarbon vapors are separated and fractionated in still 31 and pass through line 33 and valve 40 to the inlet line for catalyst chamber 4|. It is preferred .to admit a portion of the high boiling selective solvent at the top of the fractionating column of still 31. Valve controlled conduit 42 is provided for this purpose. By admission of a selective solventat this point and careful control of the temperaturein fractionating still 31, a highly naphthenic hydrocarbon fraction substantially free of aromatic compounds may be obtained as overhead for admission to catalyst chamber 4|. Sharp fractionation in still 31 also serves to further eliminate potential catalyst poisons, such as sulfur and nitrogen compounds by retaining them in the selective solvent, as well as to supply substantial pure naphthenes to the catalytic treating zone.

Olefine polymers in vapor phase pass by way of valve 43 and, together with the naphthenic hydrocarbon fraction, through mixing orifice 44 into the catalytic, treating zone represented by catalyst chamber 4|. The reaction mixture from chamber 4| flows through conduit 45 to fractionating tower 46. Inlet pipe 41 serves to admit a high boiling selective solvent to the top of tower 46 for extraction and simultaneous distillation of the reaction mixture. The vapor phase ramnate from tower 46 comprises high octane hydrogenated olefine polymers and flows from the top of the tower by way of line 48 and condenser 43 to storage. A valve controlled reflux line 50 is provided for returning a portion of the overhead to the top of the extraction tower. The selective solvent passes from the bottom of the tower into pipe 5| and vaporizer 52. A controlled portion of the dissolved compounds is vaporized and flows through conduit 53 either by way of valve 54 to the bottom of tower 46, where the vapors serve to control the temperature in the tower and are again extracted, or by way of valve 55 to catalyst chamber 56, or the vapors may be split and pass both to the tower and the catalyst chamber. It is preferred to control the temperature in vaporizer 52 so as to preferentially vaporize the dissolved naphthenes and preferentially retain the aromatics in the selective solvent. By so doing, di-isobutylene can be admitted through line 51 controlled by valve 58, mixed with the naphthenes and converted to a mixture of iso-octane and aromatic compounds in catalyst chamber 58 by the simultaneous hydrogenation of the di-isobutylene and dehydrogenation of the naphthenes in the same manner as in previous catalyst zones.

The reaction mixture from chamber 56 then flows through line 59 to extraction tower 50 of the same type as tower 46. Selective solvent from vaporizer 52 passes to the top of tower 60 by way .of pipe BI and extracts the aromatic compounds Substantially pure.

from said reaction mixture. iso-octane may be obtained as overhead and flows by way of line 62 and condenser 63 to storage. Valve controlled reflux line 64 is also provided for tower 60. The extract from this tower comprising substantially pure aromatic hydrocarbons dissolved in the selective solvent flows to vaporizer 68 by way of conduit 88. The aromatic hydrocarbons are vaporized from the solvent and pass through condenser 61 to storage. A portion of these vapors is returned to the bottom of tower in those cases that involve a boiling range above the initial boiling point-of the selective solvent, requires a modification of the solvent extraction stage of the process. Since it is not feasible to 60 by way of valve controlled line 68 for the pur- 5 separate the high boiling hydrogenated olefines pose of controlling temperature in the tower. asvapor phase, these compounds may be removed The selective solvent, stripped of its dissolved from t tower as separate n m phase The hydrocarbons, passes through conduit 60 and unconverted naphthenes may be removed as goolerblg to inlet 33 of tower 32, as P ev l vapor phase overhead and the aromatics sepaescr The reaction occurring m the hydrogenationf I rated with the selective solvent as dissolved there 3 in, Thus, a three-way separation is obtainable dehydrogenation zone is believed to berepresented by following equation, in a single extraction tower, namely, naphthenes and oleflnes as vapor phase rafllnate, high boil- 3 olefines+1 naphthene 3 parafiins-i-l aromatic mg paramns as n phase ramnate, and arm For purposes of illustration, the following commatics as liquid Phase extract. These sep rate prise specific examples of catalysts and conditions fractions will be h ndled in the m Way s the of operation which are suitable for the hydrocorrespondingrractions in flow sheets Figures I genation-dehydrogenation zones: and II, the only diflerence being the point at Table I Tempera- Catalyst ture of ex- Pressure Space velocity Stock treated periment Lba/aq. Vols. 11 .1001. F. in. cat. per hour Copper chromite 870-900 Atmos. 0.37 "28%" F. cut natural petroleum 23% aviation cut butyleue poly- Copper chromite 90o 200 o. 33 amigo-300 F. cut natural petrole m aviation cut butylene poly- Nickel chromite 900 200 0. 25 Do Nickel chromite 900 200 0. 17 D0. eraeaeizee--- g"- 0 900 200 0.33 o. ]???2Tfffii1 e00 200 0. as Do.

In general, it has been found that the temperature in the catalytic chambers should be maintained below approximately 1000 F. Temperatures as low as 400 F. are operative with some catalysts and on some stocks. Catalysts which promote both hydrogenation and dehydrogenation reactions in this temperature range may be utilized. Additional examples are nickel and molybdenum sulfide. A number of such catalysts are known to those skilled in the art and the present invention is not concerned with the catalysts per se.

Although specific mention has been made of the treatment of di-isobutylene and although the invention at present finds its greatest utility in the treatment of dimers of two to five carbon olefines, the broader aspects of the invention are not so limited and include treatment of high polymers of these compounds, such as high boiling polymers useful as and/or in synthetic and compounded lubricants. Dimers formed by polymerization or copolymerization of propylene, butylenes, pentenes and mixtures of these compounds when contacted with polymerization catalysts such as phosphoric acid, hot sulfuric acid, aluminum chloride, metal phosphate catalysts such as calcium phosphate, cadmium phosphate and metaphosphates, comprise a most suitable source of olefine polymers for production of high octane parafilnic'motor fuels by the process of which they are removed from the solvent extraction stage.

The petroleum stocks which may be utilized in the present process may vary greatly in type as well as in boiling range so long as a substantial proportion of naphthenic compounds is contained therein. In order to avoid various dilficulties and minimize side reactions, it is preferred to utilize a natural petroleum cut from a highly naphthenic type crude, but Mid-Continent crudes and even cracked naphthas are operative in the process, particularly if the species of operation illustrated by Figure II is adopted. Inv the specific examples previously tabulated a 200 to 300 F. cut was adopted. It is to be understood that this boiling range merely comprises one example of a suitable material and that other petroleum fractions may be selected depending upon the aromatic compounds or compounds which it may be desired to produce.

When, for example, one wishes to synthesize benzene, a narrow cut in the benzene boiling range will be selected and supplied as stock'to be treated in the process. Likewise when toluenes or xylenes are desired, corresponding sharply frac tionated petroleum cuts may be selected. Similarly, when very high boiling aromatics of unknown or polynuclear constitution are to be synthesized, petroleum fractions boiling in the selective range will be adopted. When a lacquer diluent of low aniline point is to be produced a stock having a boiling range of from 200 to about 265 F. may be selected, and if a paint thinner is desired a 300 to 400 F. cut may be processed. An aromatic type aviation gasoline can be simultaneously produced with the parafiinic type high octane gasoline by processing a petroleum out having, for example, a 50% point at about 212 F. and a point at 275 F. The above examples will sumce to guide one skilled in the art in the selection of the stocks to be treated.

selective solvent.

- The relative proportion of petroleum fraction to olefine generally should be such that there is at least one naphthene ring for each three 01efine bonds to be hydrogenated. An excess of naphthenes is generally desirable, at least in the first stages of a multi-stage process, in order to afford the most economic utilization of the olefine polymers. In those cases where production of aromatics is the primary object, an excess of olefines may be utilized.

The vapor phase selective solvent extractio stages of the process may be carried out in any known suitable type of frac ionating-v column whether it be a tower filled with a packing of refractory earthenware, glass, etc., or a tower constructed in the same manner as an ordinary fractionating column of the bubble cap type. In order to better understand this stage of the process, the action on a bubble plate will be considered in some detail. The reaction mixture from a catalyticstage enters the tower in vapor form and is quenched in the liquid phase selective solvent flowing across the bubble plate. -The'temperature of the solvent in the tower may be maintained above the boiling point of the hydrocarbon mixture under the conditions of extraction by controlling the temperature of the selective solvent entering the top of the tower, by controlling the temperature of the reaction mixture admitted to the tower and by controlling the amount of vapors recirculated from the vaporizer connected to the bottom of the tower. The selective solvent should be maintained at a temperature below that at which the aromatic hydrocarbons will be vaporized from the This temperature may vary widely depending upon the ratio of solvent to aromatics. In general, although higher temperatures are operative, a practical upper limit of temperature is the end point of the stock being extracted and temperatures in the order of to 60 F. above the dew point of the aromatic components of the stock under the .conditions existing in the extraction tower are preferable.

By controlling the temperature, as previously indicated, the hydrocarbon vapors are simultaneously selectively extracted as they pass through the selective solvent and are fractionated as they pass upwardly through the fractionating column. The vapor phase hydrocarbons from the catalytic stage are sufliciently hot to serve as a source of heat for the fractionation in the extraction column. At the same time the vapors are giving up their heat to produce fractionation of those hydrocarbons which have been previously condensed, these hotter vapors are being quenched by direct contact with the cooler selective solvent. Inasmuch as the volume of selective solvent is usually two or more times that of the hydrocarbons being extracted (measured as liquid phase) the dissolution of unsaturated compounds, for example, serves to dilute the mixture, and by reason of this dilution to decrease the rate at which various undesirable side reactions may progress. Furthermore, the sudden cooling of the hydrocarbon reaction mixture also tends to prevent or decrease undesired side reactions, particularly polymerization, and consequently reduces the extent of gum formation and the extent of catalyst poisoning by preventing the initial recovery by water extraction is possible and the solvent is therefore suitable for use in such a modified method of treatment. The. following comprises a list of high boiling selective solvents which-are operative in the extraction stage of the present invention:

Solvent 410 at 20 mm.

Dibutyl phthalate Although a number of specific examples of suitable selectlve solvents have been given and although triethylene glycol and tetramine constitute preferred examples of solvents, it should be apparent to those skilled in the art that the .broader aspects of the invention include the use of a, multitude of other high boiling selective solvents.

It is to be understood that the process of this invention may be carried out under sub-atmospheric, atmospheric or super-atmospheric pressures, and that the drawings are merely diagrammatic in character, no attempt having been made to illustrate an apparatus embodying all the necessary details such as valves, pumps, and pressure control devices. The provision of suitable apparatus for carrying out the process is regarded as within the skill of a petroleum technician. Common forms of catalyst chambers, supports for catalyst beds, heating and cooling means to control the temperature of the catalyst and the temperature of the petroleum vapors may be utilized.

While the character of this invention has been described in detail and numerous illustrative examples given, this has been done by way of exemplification only and with the intention that no limitation should be imposed upon the invention thereby. It will be apparent to those skilled in the art that numerous modifications and variations may be effected in' the practice,

of the invention which is of the .scope of the claims appended hereto.

I claim:

1. A process which comprises forming a mixture of olefins and naphthenes, passing said mixture at an elevated temperature over a cata-;

reactions and effect a separation of paraffin from cyclic hydrocarbons, separating said solvent containing dissolved cyclic hydrocarbons from undissolved paraflinic vapors, and recovering naphthenes and aromatics from said solvent.

2. A process which comprises forming a mixture containing naphthenes and a polymerization product of two to five carbon olefins, passing said mixture at an elevated temperature over a catalyst in a hydrogenation-dehydrogenation zone whereby naphthenes are dehydrogenated to aromatics and said olefin polymers are hydrogenated to paraflins, quenching the vapors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesired side reactions and effect a separation of paraffin from aromatic hydrocarbons, separating said solvent containing dissolved aromatic hydrocarbons from undissolved parafiinic vapors, and recovering aromatics from said solvent.

3. A process which comprises forming a mixture containing naphthenes and di-isobutylene, passing said mixture at an elevated temperature over a. catalyst in a hydrogenation-dehydrogenation zone whereby naphthenes are dehydrognated to aromatics and said di-isobutylene is hydrogenated to paraflins, quenching the va pors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesired side reactions and effect a separation of paraffin from aromatic hydrocarbons, separating said solvent containing dissolved aromatic hydrocarbons from undissolved parafiinic 5. A' process which comprises mixing a petroleum fraction containing naphthenic hydrocarbons with a high boiling organic selective solvent for cyclic hydrocarbons, selectively vaporizing a highly naphthenic hydrocarbon fraction from said selective solvent whereby catalyst poisons are selectively dissolved and said naphthenic hydrocarbonsare substantially freed of sulfur and nitrogen compounds, forming a mixture of an olefin and said naphthenic fraction, passing said mixture at an elevated temperature over a catalyst in a hydrogenation-dehydrogenation zone whereby naphthenes are dehydrogenated to aromatics and olefins are hydrogenated to paraffins, quenching the vapors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesired side reactions and effect a separation of paraffin from cyclic hydrocarbons, separating said solvent containing dissolved hydrocarbons'from undissolved parafiinic vapors, and

' recovering aromatics from said solvent.

vapors, and recovering aromatics from said 501- vent.

4. A process which comprises forming a mixture of olefins and naphthenes which boil substantially in the range of motor fuel, passing said mixture over a catalyst in a hydrogenationdehydrogenation zone at a temperature of from approximately 400 F. to approximately 1000 F. whereby naphthenes are dehydrogenated to aromatics and olefins are hydrogenated to paraffins, quenching the vapors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesired side reactions and effect a separation of paraflinic from cyclic hydrocarbons, separating a vapor phase hydrogenated olefin fraction, separately removing a naphthenic hydrocarbon fraction from solution in said selective solvent, returning said last fraction to a hydrogenation-dehydrogenation zone, and vaporizing the remaining aromatic comto selectively dissolve aromatic and naphthenic hydrocarbons from said mixture in said solvent, selectively distilling naphthenic hydrocarbons from said high boiling organic selective solvent, mixing a polymerization product of two to five carbon olefins with said distilled naphthenic hydrocarbons, passing said mixture at an elevated temperature over a catalyst in a hydrogenationdehydrogenation zone whereby naphthenes are dehydrogenated to aromatics and olefins are hydrogenated to paraflins, quenching the vapors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesiredside reactions and effect a separation of paraffin from cyclic hydrocarbons, separating said solvent containing dissolved aromatic hydrocarbons from undissolved paraffinic vapors, and recovering aromatics from said solvent.

7. A process which comprises forming a mixture containing an olefin andanaphthalene, alternately passing said mixture at an elevated temperature over a catalyst in a hydrogenation-dehydrogenation zone whereby naphthenes are dehydrogenated to aromatics and olefins are hydrogenated to paraflins and quenching the vapors leaving each of the alternate hydrogenation-dehydrogenation zones by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneouslystop undesired side reactions and effect a separation of aromatic hydrocarbons, separating said solvent containing dissolved aromatic hydrocarbons from undissolved vapors, and recovering aromatics from said solvent.

8. A process which comprises forming a mixture of olefins and paraffins, passing said mixture at an elevated temperature over a catalyst in a hydrogenation-dehydrogenation zone whereby naphthenes are dehydrogenated to aromatics and olefins arehydrogenated toparaifins, quenching the vapors leaving said zone by direct contacting with a high boiling organic selective solvent for cyclic hydrocarbons in liquid phase to simultaneously stop undesired side reactions and effect a separation of paraffin from cyclic hydrocarbons, maintaining said selective solvent at carbons from said solvent.

raflinate phase, returning said vapor phase naphthenes to a hydrogenation-dehydrogenation zone, separating said high boiling liquid phase paraffln hydrocarbons ifrom said selective solvent, and recovering dissolved aromatic hydro- PHILIP/S. DANNER.

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