US2001634A - Petroleum product - Google Patents

Description

y 1935- D. R. STEVENS El AL 2,001,634

PETROLEUM PRODUCT Filed Dec. 1, 1951 pnivoub COMPOUND MIXING BE FLUX V CON]? E N55 )2 SEPARATION F/msH/rvs STEPS Donald R. Te vews,

Williamul Gruse Patented May 14, 1935 2,001,634 PETROLEUM PRODUCT Donald R. Stevens, Pittsburgh, and William A.

Gruse, Wilkinsburg,

Pa., assignors to Gulf Refining Company, Pittsburgh, Pa., a corporation of Texas Application December 1, 1931, Serial No. 578,412

12 Claims.

This invention relates to improvement of petroleum products; and it comprises methods of improving the character of various petroleum oils, such as reduced crudes, cylinder stocks, parail'in wax, distilled lubricating oils, cracked distillates, distillates from cracked distillates,

etc., wherein such a product is heated for a time with a small'amount of a mixture of aluminum chlorid and a phenolic compound; said methods of improving petroleum products including the refining of cracked distillates, such as gasoline, by heating the same at moderate temperatures below those at which conversion commences and usually under a reflux condenser or, alternatively, at somewhat higher temperatures and under super-atmospheric pressures; said methods also including the converting of high boiling petroleum oils, such as solar oils, into lower boiling products, such as gasoline, conversion being conducted at temperatures ranging from 380 to 480 C. and at pressures ranging from atmospheric to about 3500 pounds per square inch; all as more fully hereinafter set forth andas claimed.

The present application is a continuation in part of our copending application, Serial No. 572,883,-filed November 3, 1931. The invention described and claimed herein covers the matter of this prior application together. with certain extensions and improvements relating to the production of light distillates of the nature of gasoline from higher boiling oils.

Many petroleum products contain small amounts of unstable constituents which lead to yellowing,. are susceptible to oxidation and are generally undesirable. The distillates and residual oils resulting from modern cracking distillation of peteroleum oils and distillates are highly unsaturated in character and are not particularly stable in storage, tending to develop color and gum. This is true not only of distillates from pressure cracking and from the socalled vapor phase cracking where little pressure is used, but it is also true of products made from such distillates by redistillation. Naphtha, gasoline and kerosene resulting from redistillation of cracked distillates contain large amounts of unsaturates. The unsaturation of the products of cracking distillation is mostly due to stable olefinic hydrocarbons and these are desirable components. The rest of the unsaturation is due to small proportions of much less stable hydrocarbons; these probably having acetylenic, diolefinic and cyclic olefinic linkages, and being responsible for color, development of gum and oxidative changes. In the case of many of these oily materials, such as reduced crudes, cylinder stocks, paraflin wax and distilled lubricating oils, a moderate purifying action is desirable.

There is considerable difliculty in economically refining these various products, and particularly the gasoline, by ordinary refinery methods. The use of sulfuric acid in the amounts usually employed is uneconomical, because of the loss of oil. Sulfuric acid has several actions contributing to this loss; it condenses and polymerizes olefins to higher boiling oils and it withdraws considerable proportions of the liquid. In refining cracked gasoline, even with small amounts of sulfuric acid, it is impossible to confine the action to the undesirable, highly unstable unsaturates; there is always a subtraction of valuable oil and a formation of high boiling ends. A somewhat similar formation of high boiling ends occurs in the use of anhydrous aluminum chlorid. The chlorid in contact with the oil at low'temperatures, say below 65 0., and in the usual amount of about 5 per cent or less, does not change the character of the gasoline particularly, insofar as the production of lower boiling hydrocarbons is concerned; but it does remove a considerable proportion of the unsaturates and in so doing, produces higher boiling oils. This increase of heavy ends is sometimes called the polymerization loss. And a simple diminution in the amount of aluminum chlorid does not refine; the oil is not stabilized.

As is well known, anhydrous aluminum chlorid exercises several actions on petroleum oils. One, which may be termed the refining action, takes place at low temperatures and results in the obviation of unsaturation, removal of sulfur, etc.

The other, which may be termed the converting action, takes place at higher temperatures and results in a drastic rearrangement of the molecular structure of the hydrocarbons of the oii. Under proper conditions this so-called converting action can be used to produce low boiling oils from high boiling oils. In this production, the refining action also takes place.

The difliculty in the use of aluminum chlorid for refining pressure distillates and similar petroleum oils lies in the energy of its action. It is diflicult; to control conditions so that merely the highly unsaturated and unstable bodies are affected while the other stable and valuable un-' saturates are unaflected.

We. have found that a moderation of activity of the aluminum chlorid in the desired direction compounds in a co-pending application, Serial No. 572,883, ,filed November 3, 1931. We have found that when aluminum'chlorid is so mixed or combined with these oxygen-containing carbon compounds of the aromatic series and of the nature of phenols, the energy of its reaction with petroleum hydrocarbons is much lessened. Our additive compound or complex tones down the activity of the aluminum chlorid selectively. Quantitatively, the aluminum chlorid still'exercises as much favorable action as before, in fact, less is required for its normal action; the restraint is merely as to undesired violence of action. Such being the case, compositions of this type are well adapted for refining pressure distillates and the like where the problem is to remove highly reactive bodies without aifecting less reactive ones. In particular, they can be used to eliminate or to render innocuous gumforming components.

Byithis restraint in activity, the action, at

' lower temperatures, can be limited to what we have termed the refining action, as distinguished from the rearranging or converting action which ordinarily takes place with aluminum chlorid. And, further, in thisrefining action, it is quite possible to limit the action to the most sensitive impurities present. For example, in many of these oils, olefins, which are desirable compounds for gasoline, etc., are present and, in addition, diolefins and other unsaturated bodies of highly reactive nature. It is possible to use aluminum chlorid, suitably combined, to obtain the limited refining action necessary to dispose of these latter highly reactive unsaturates while leaving the desirable, less reactive unsaturates in the compounds. Byrestraining the activity of. the aluminum chlorid, there is also less loss due to polymerization and depolymerization. In operating under the present invention, the overall quantity of aluminum chlorid necessary is much lessened and the results are more precise and better.

Our aluminum chlorid additive compounds give a much easier operation than'the use of aluminum chlorid alone, in the sense that fewer precautions are necessary. As the amount of gum-forming bodies in the gasoline or of high-' ly unstable bodies in other oils is always small, not much of these compounds need be used to attain all the refining desired.

Our additive'compounds are sufilciently' reactive to enable low temperatures to be employed and atmospheric pressures. Usually moderate temperatures ranging from 65 to C. are sufliciently high for operation at atmospheric pressures. The time required for treatment usually amountsto from 30 to minutes. The reaction may be carried out under a reflux condenser without serious volatilization losses. Certain advantages are obtained, however, by conducting thetreatment at temperatures only slightly below those at which conversion enters and at superatmospheric pressures. These advantages will be discussed subsequently.

Any of the ordinary phenols may be used as moderating agents. We have employed phenol itself, the various cresols, a dehydrated crude tar acid from coal tar consisting of about twothirds phenol and one-third cresols, resorcinol and alpha-naphthol with good results. Crude coal tar distillates containing crude phenols as well as appreciable concentrations of other aromatic hydrocarbons are applicable. Phenolic compounds in general appear to be suitable, this term including homologues.

Our invention can be described by reference to the accompanying drawing which shows, in the form of a fiow sheet, a specific embodiment thereof, wherein a charge oil is treated by a series of successive operations with the ultimate production of a finished oil. The several operations of our process are indicated in the fiow sheet by appropriate legends.

As shown in the drawing, anhydrous aluminum chloride is mixed withv a phenolic compound, with or without the aid of a diluent, to form an aluminum chloride complex. This is mixed with the charge oil, the'mixture being then treated, usually under a reflux condenser. The treating step is followed by separation of sludge and by conventional finishing steps with eventual recovery of a finished oil. These'several process steps are clearly illustrated in the flow sheet.

In a particular embodiment of the present invention, illustrating the refining of a certain gasoline, aluminum chlorid was combined with ordinary phenol in the molecular proportion of 1:1. The two materials were mixed and formed a pasty composition. As this composition was somewhat difiicult to mix with petroleum oils, it was found convenient to bring it into solution with a suitable solvent such as benzene. The solution was added to a condensate of naphtha from a pressure cracking operation in the proportion of 1.0 per cent by weight of the aluminum chlorid plus a molecular proportion of phenol, amounting to a total of about 2.0 per cent by weight of the compound. On adding the benzene solution of phenol and aluminum chlorid to the naphtha, the complex dispersed as a fiufiy precipitate which was readily stirred through the liquid and kept in suspension. The amount of benzene used was about one or two per cent of the naphtha. This mixture was heated for about an hour under a reflux condenser at atmospheric pressure and at a temperature of about 90 C. After this operation was complete, the complex separated readily as a dense tar easily removed.

After the heating operation, the naphtha was washed with alkali solution and then with water and finally distilled to 200 C. The polymerization loss was 1.5 per cent, while the'loss to sludge was only 0.5 per cent in this opera- I tion.

Recovery of the final products after treatment with our additive compounds is by conventional refinery processes such as water or alkali washing and distillation or, in the case of lubricating oils, clay contact, or an acid wash followed by clay filtration.

In order to demonstrate the advantages in the use of additive compounds over the use of aluminum chlorid alone, the above operation was duplicated except for the omission of the molecular proportion of phenol. In this case the loss by polymerization increased to 9.5 per cent while the loss to sludge was 2.5 per cent. In addition a lower degree of refining was obtained than in the former operation. In a general way it has 'ment of about 2 minutes.

in refining as 1 per cent of aluminum chlorid used alone.

In another specific embodiment of our inven-' tion, a high temperature, pressure still distillate, originally cut to 150 C. was employed. This distillate had a. copper-dish gum content of 300. It was treated for 1 hour at 90 C. and at atmospheric pressure with 3 per cent aluminum chlorid plus a molecular proportion of phenol, dissolved inbenzene. After treatment the mixture was cut to 150 C. The product showed a copper-dish gum content of substantially zero and constituted an excellent aviation gasoline.

While the above examples show that the refining of light distillates can be conducted efiiciently at atmospheric pressure, certain ad'- vantages arise from the use of elevated pressures and temperatures. Thus, in one operation there was added to a vapor phase distillate cut to 200 0., direct from vapor phase still 0.25 per cent; of aluminum chlorid plus a molecular proportion of tar acid. This tar acid, was a crude commercial composition containing phenol and cresols. The mixture of distillate, aluminum chlorid and tar acid was heated for 2 minutes in a closed vessel at a temperature of 400 C., the pressure being maintained at about 1000, pounds to the square inch. By this treatment the original copper dish gum content of the distillate, namely 445, was reduced to a value of 59. The gum as determined by the so-called oxygen test was correspondingly reduced from a high value to 16. A polymerization loss of only 2.4 per cent was encountered.

In a second operation at superatmospheric pressures a pressure still distillate, originally out to 200 C. was treated with 0.25 per cent aluminum chlorid plus a molecular proportion; of phenol at 300 C. for 2 minutes and at 1000 pounds pressure. The final product was found to have copper-dish and oxygen gum contents of 20 and 40, respectively. This is in comparison with original values of 467 and 731, respectively.

The polymerization loss in this run was only 3.8 per cent. r a

The above two examples of refining under superatmospheric pressure cleai'ly indicate the advantages to be derived from the use of such pressures. The amount of aluminum chlorid required is reduced to about one fourth. The time required for treatment is reduced from about an hour to 2 minutes. The loss by volatilization is reduced and the polymerization loss is usually lowered somewhat.

It was found that all of the above described distillates were much improved in quality and that there was relatively little loss by condensation or polymerization. It has been found that it is not necessary to employ a benzene solution of the compound catalysts as described in the first two examples, the benzene solution is employed merely for convenience in mixing. There is also little or no loss of material to sludge.

In the refining of light petroleum products under superatmospheric pressures, the conditions of the treatment can be varied considerably. The optimum values for vapor phase distillates cut to bout 200 C. are about as follows: a concentrati n of about 0.25 per cent aluminum chlorid plus a. molecular proportion of phenol, a temperature of about 400 C., a pressure of about 1000 pounds per square inch and a time of treat- With pressure, still distillates the optimum temperatures appear to lie somewhat lower, say from 300 to 350 C.,

the other optimum values remaining about the same. Pressures above 2000 pounds cause a. greater loss by polymerization and produce somewhat less refining. Conversion becomesperceptible during treatment of these light products at temperatures of about 400 C. At temperatures above 420 C. substantial conversion occurs which causes increased loss by the formation of so-called permanent gases.

We have thus found that light distillates can be efiiciently refined at temperatures ranging from about 65 to 420 C. and at pressures from atmospheric to 2000 pounds per square inch. The effective quantities of our additive compounds which may be used range from about 0.2 to 3 or possibly as high as 5 per cent of aluminum chlorid plus a certain amount of oxygen containing, organic moderating agent. Usually the latter is used in molecular proportions. An excess does no harm and has some advantages in reducing the polymerization loss and the loss to sludge. Proportions up to 3 or 4 mols of the retarding agent to 1 of aluminum chlorid may be employed although the cost of such agents usually militates against the use of more than molecular proportions. The use of less than molecular proportions produces effects intermediate those produced by aluminum chlorid alone and by molecular proportions of aluminum chlorid and retarding agent.

The amount of aluminum chlorid additive compounds to be used varies with the particular petroleum product treated and with the result sought, but is, in all cases, small. When heavy products, such as lubricating stocks are being treated, at low temperatures, up to 5 per cent of the additive product may be used. With such products the use of our additive compounds instead of aluminum chlorid itself results in a striking reduction in loss to sludge. Naturally, the amount to be used depends in a measure on the amount of highly unstable bodies present and to be removed. In refining cylinder stock, medicinal oils, paraffin wax, lubricating oils, etc. somewhat larger amounts of our additive compounds may be used in obviation of unstable minor constituents without substantial change otherwise in the character of the oil.

While it has been proposed to treat oils, for removal of gum and resinifying constituents, by heating'the same with solutions of aluminum chlorid in various solvents such as ethyl ether, nitrobenzene, normal propyl alcohol and ethyl acetate, we have found that the alcohols and acetone, for example, are not as good as the phenols in the processes of the present invention.

In our processes crude aluminum chlorid has been successfully employed, this material containing appreciable quantities of ferric chlorid. In fact ferric chlorid itself may be used and may be considered the equivalent of aluminum chlorid for the purposes of this invention.

The reason for the alteration of the chemical properties of aluminum chlorid in forming these additive compounds is not known. It is, however, our belief that a combination of aluminum chlorid with a hydrocarbon molecule is a precedent to either the refining or the converting action mentioned; and that in forming a tolerably stable additive compound with an organic body of a difierent type the energy of action of the aluminum chlorid is simply restrained; it is, so to speak, made milder in its action. At all events, by using an additive compound of aluminum chlorid and phenol, the refining ac-'- additive compounds by adding the correctamount of aluminum chlorid to a phenol. This makes a liquid product which is readily handled. If desired, it may be diluted with a little benzol .or with some of the oil to be treated. This is a matter of mechanical convenience and does not alter the results. Nor are the results altered by making the catalyst in the oil to be treated, as by adding the phenol to the oil and afterward adding the aluminum chlorid. Union of phenol with the aluminum chlorid appears to be a preferential action.

We regard the use of as oflering advantages over the use'of aluminum chlorid alone where the action to be attained is-merel'yrefining without conversion; without producing a change in the essential character of the oil or material to be treated. There are, however, advantages in using the aluminum chlorid additive compounds in converting operations. For one thing, there is less loss in the production of gas and of coke.

In illustrating the use of the present catalyst for conversion, a solar oil heated at 450 C. with 2 per cent of aluminum chlorid combined with an equimolecular amount of phenol gave a gasoline yield of 44 per cent with a zero coke loss and a gas loss of per cent. A pressure of 3000 pounds per square inch was used. Exactly the same operation with the same materials, but using aluminum chlorid alone in the same amount, gave a little more gasoline, 47 per cent, in lieu of 44 per cent, but there was a coke loss of 4.4 per cent and a gas loss of 18 per cent. The use of the additive compound gave a little less gasoline than aluminum chlorid alone, but the loss and the deterioration of the residual oil were both less.

In another operation a Mid-Continent solar oil, was treated, at a temperature of 435 C. and a pressure of 1450 pounds per square inch, with 1 per cent of aluminum chlorid combined with a molecular proportion of phenol. The gasoline yield was 30 per cent, the coke loss was zero while the gas loss was, 4.2 per cent. When another run was made under the same conditions but with omission of the molecular proportion of the phenol, a gasoline yield of 30.9 per cent was obtained. The coke loss was 0.3 per cent while the gas loss amounted to 8.7 per cent. When conditions in this operation were varied by using a temperature of 440 C. and a pressure of 2500 pounds per square inch, the gasoline yield (using 1 per cent of aluminum chlorid plus a molecular weight of phenol) was increased to 35.4 per cent. The coke loss was again zero while the gas loss amounted to 8.2 per cent. Under the same conditions but omitting the molecular proportion of phenol, a gasoline yield of 35.9- per cent was obtained. But in this case there was a coke loss of 1.5 per cent and a loss to gas of 112 per cent. Gas losses as stated include a handling loss of the order of 1 per cent. This loss was fairly constant in all cases. I

It'is obvious that the conditions under which the above converting operations may be carried out are capable of considerable variation.

the described catalysts For example, pressures can be varied all the way from atmospheric to 3500 pounds per square inch. The favorable pressure range lies between about 1000 and 3000 pounds per square inch with an optimum value at about 2500 pounds. Above this latter value the yield ceases to rise rapidly. The temperatures employed in our converting operations may be said to lie within the lower part of the range required for thermal cracking. Thus temperatures from about 380 C. to 480 C. are operative. temperature range for the above converting operations is between about 420 to 460 C. Above this range high gas formation sets in. .If recycling is contemplated the upper temperature limit is about 440 C.

The advantageous For heavy naphthas advantageous conversion temperatures lie between about 400 and 450 C. Change 5 in pressure with this material has less effect on yield; pressures of 1000 to 2500 pounds per square inch are satisfactory. The

heavy products employed in the converting operations are somewhat more susceptible to conversion than are the lighter products used in refining operations. Conversion-commences at somewhat lower temperatures. Thus, while light products can be refined at temperatures up to 420 C. without substantial conversion; the heavier products can be converted effectively at temperaturesas low as 380 C.

The amount of additive compound to be used in converting operations varies somewhat with the temperature and with the particular stock .employed. An amount equivalent to 1 per cent of aluminum chlorid with an equimolecular proportion of phenol is generally sufllcient for all purposes. portion of additive compound increases the yield somewhat. A range of from 0.5 to 3.0 per cent of aluminum chlorid plus an equimolecular proportion-of phenol covers the favorable range withan optimum value in the neighborhood of 1 per cent. The operative range is somewhat larger.

Our new complexes may be utilized in a number of processes in refining petroleum oils, in conversion and in securing other results. The complexes may be used, for example, in converting gaseous hydrocarbons into liquid; or for inducing condensation of gaseous'hydrocarbons with liquid hydrocarbons; as in causing relatively heavy oils to take up refinery gases under heat and pressure. The compound catalyst is also useful in hydrogenation of mineral oils and the like, and especially in the conversion of heavy oils into lighter oils.

Most of these processes may be conducted throughout a large range of pressures .varying' all the way from 3500 pounds per square inch to pressures even below atmospheric.

What we claim is:

1. In the improvement of petroleum distillate and residual oils, the process which comprises treating such an oil at temperatures ranging from about 65 to 480 C. with a small proportion of a mixture of anhydrous aluminum chlorid and an added organic moderating agent selected from a class consisting of phenolic compounds and their homologues,- said organic moderating agent being added in amount sufflcient to substantially restrain the activity of said aluminum chloride.

- 2. In the improvement of petroleum. distillate and residual oils, the process which comprises At, low temperatures a larger pro-- treating said oil at temperatures ranging from u about to 480 C. with a small proportion of a mixture of anhydrous aluminum chlorid and an added phenolic compound, said phenolic compound being added in amount sufllcient to restrain the activity of said aluminum chloride.

3. In the improvement of petroleum products, the process which comprises treating a cracked distillate with a small amount of a mixture of anhydrous aluminum chlorid and an added phenolic compound; said reaction taking place at temperatures below those producing any substantial conversion of said cracking distillate and said phenolic compound being added in amount sufllcient to restrain the activity of said aluminum chloride to a point at which the polymerization loss is appreciably decreased.

4. In the improvement ot-petroleum products, the process which comprises treating a cracked distillate with a small amount of an equimolec ular mixture of anhydrous aluminum chlorid and added phenol at temperatures ranging from about 65 to C. and at atmospheric pressure to eliminate gum-forming bodies and otherwise refine said distillate.

5. In the improvement of petroleum products, the process which comprises heating a light, cracked, petroleum distillate tor a short time with a mixture of from 0.2 to 5.0 per centoi anhydrous aluminum chlorid and a 'small amount of an added phenol, at temperatures from 65 to 420 C. and at pressures ranging from atmospheric to 2000 pounds per square inch and said phenol being added in amount sutilcient to substantially moderate undesirable activity of the aluminum chloride; said distillate being of such type that substantially no conversion thereof takes place under the conditions stated.

6. In the improvement of petroleum products, the process which comprises heating a light, cracked, petroleum distillate for about 2 minutes with a mixture of about 0.25 per cent 0! anhydrous aluminum chlorid and an equimolecular proportion of phenol, at temperatures from about 300 to 400 C. and at pressures of about 1000 pounds per square inch; said distillate being of such type that substantially no conversion thereof takes place under the conditions stated.

7. In the improvement of petroleum products,

I the process which comprises heating oils capable of conversion into distillates of lower boiling point to temperatures ranging from about 380 to 480 C., in the presence of an equimolecular mixture of anhydrous aluminum chlorid and pound being added in amount sufllcient to moderate undesirable activity of said aluminum chloride.

8. In the improvement of petroleum products, the process which comprises converting oils suitlower boiling point in the presence of a mixture of anhydrous aluminum chlorid and an added oxygen containing organic moderating agent selected from a group consisting of phenols and their homologues at elevated temperatures within the lower part of the range required for thermal cracking, said agent being added in amount sufllcient to moderate undesirable activity of said aluminum chloride.

9. In the improvement of petroleum products,

the process which comprises converting oils suitable for producing gasoline into distillates of lower boiling point in the presence of an equimolecular mixture of anhydrous aluminum chlorid and an aromatic alkoxy compound but in the absence of added hydrogen, at elevated temperatures within the lower part of the range required for thermal cracking.

10. In the improvement of petroleum products, the process which comprises converting oils suitable for producing gasoline into distillates of lower boiling point in the presence oi a small quantity of a mixture of anhydrous aluminum chlorid and an added phenolic compound, said,

compound being added in amount sufficient to substantially moderate undesirable activity 0! said aluminum chlorid.

11. In the improvement of petroleum products, the process which comprises converting oils suitable ior producing gasoline into distillates 01 lower boiling point in the presence of a mixture oi. from 0.5 to 3.0'per cent of anhydrous aluminum chlorid, a small amount of a phenol and in the absence of added hydrogen, at temperatures from 380 to 480 C., and at pressures ranging from atmospheric to 3500 pounds per square inch, said phenol being added in amount sumcient to substantially reduce the gas and coke'loss incident to conversion. I

12. In the improvement of petroleum products, the process which comprises converting oils suitable for producing gasoline into distillates o1 lower'boiling point in the presence of a mixture of about 1 percent anhydrous aluminum chlorid,.

an equimolecular proportion of phenol and in the absence of added hydrogen, at temperatures from 420 to 460 C. and at pressures of about 1000 pounds per square inch.,

an added oxygen containing, organic compound selected from a class consisting of phenolic compounds and their homologues said organic com- Domm s'mvrms. WILLIAM a. cause.

.able for producing gasoline into distillates of p

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