US1819006A - Method of treating heavy oils for the production of light oils by the employment of metallic halides - Google Patents

Description

Aug.18, 1931. w. H. SHIFE'LER 1,819,006

METHOD OEIKBATING HEAVY OILS FOR THE PRQDUGTTQN OF LIGHT OILS BY THE EMPLOYMENT 0F METALLIC HATJIDES Filed Aug. 11, 1925 Sm wag Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE WILLIAM H. SHIFFLER, OF OAKLAND, CALIFORNIA, ASSIGNOR TO STANDARD OIL COMPANY OF CALIFORNIA,

OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF METHOD OF TREATING HEAVY OILS FOR THE PRODUCTION OF LIGHT OILS BY THE EMPLOYMENT F METALLIC HALIDES Application filed August 11, 1926. Serial No. 128,711.

This invention relates to a method for cracking heavy oils for the production of lighter oils, such as naphtha or motor fuels, and refers particularly to a process wherein gmetallic halides such as aluminum chlorid are employed as catalysts at elevated pressures and temperatures. More particularly, the present invention relates to a process of distilling oil with aluminum chlorid at a pressure above atmospheric and at temperatures higher than those ordinarily used when operating at atmospheric pressure to carbon distillates. As a result of the higher pressures and temperatures used in the present process, there is a more rapid conversion of higher boiling point hydrocarbons into the desirable lower boiling point hydrocarbons without the use of such large quantities .20 of catalysts as has The conversion of the higher boiling point petroleum oils, such as gas oil, etc., to lower boiling point oils, such as gasoline, kerosene, etc., is a typical application of the present invention.

In general practice, processes employing metallic halides such as aluminum chlorid petroleum oil have been oper-.

for cracking ated at atmospheric pressure. The amount of aluminum chlorid is usually from 5 to 10 per cent. The process is operated by applying heat so that the aluminum chlorid first melts and combines with a part of the oil to form a tar which is separate from the oil.

In order to obtain contact between the oil and aluminum chlorid contained in this tar, the mixture is agitated continuously during the process. The temperature of the mixture increases until a'temperature is reached 40 where the lower boiling point hydrocarbons begin to distill from the mixture. This temperature may vary between wide limits, depending upon the type of petroleum being treated and the amount of aliuminum chlorid that is used with it. The lower boiling point hydrocarbon vapors are passed to a reflux condenser where the hydrocarbons having higher boiling points than those desired in the distillate are condensed and returned to the still, together with any Volatile coma produce the same hydro-.

heretofore been required.

pounds of aluminum chlorid that may be contained in them. The desired hydrocarbons are then condensed in a final condenser. A thermometer is usually placed in the vapor outlet from the reflux condenser in order to control the end boiling point of the hydrocarbonsentering the final condenser. hen producing U. S. motor grade gasoline having an end boiling point of not over 437 F as determined by U. S. Bureau of Mines specifications, this control thermometer is held at a temperature around 300 F during the entire distillation. As the heating continues, the rate of distillation drops off rapidly, the tar phase in the still increases, and the still temperature must be gradually increased to maintain the desired temperature at the vapor outlet. It is generally necessary with this type of process to continue the process for 48 hours or more, in

obtaining the last half of the low boiling point hydrocarbons that the process is very expensive.

It has heretofore been suggested that pressure be employed in such a process for the purpose of reducing the heat requirements. However, the prior attempts employing above atmospheric pressure have always contemplated the use of the same temperature as is common to employ when conducting the process at atmospheric pressure upon a theory that the conversion process is a chemical action rather than a decomposition due to a boiling action; that the boiling action should be reduced by the use of low temperatures in order to permit maximum results from the chemical action. Thus, for example, where a process at atmospheric pressure employed a temperature of from 500 to 550 F"., that .when so operating at 15 pounds pressure abo e atmospheric, it has been proposed to employ the same temperature, or a temperature between 500 and 550 F.

I have found that by distilling petroleum oils in the present of a metallic halide catlyst at. both above atmospheric pressure and at higher still temperatures, the catalyst may be made to act upon the oil at a much more rapid rate, thereby greatly increasing the rate of distillation and permitting the production of a large quantity of low boiling point hydrocarbons from a given quantity of catalysts and also greatly reducing the fuel consumption in the process. For example, I have di covered that approximately double the yield may be obtained in the same length of time by the joint use of both increased temperature and pressure over a process operating at atmospheric pressure and at normal boiling temperatures.

This invention will be more readily understood from a description of a preferred form or example of a process embodying the invention. A. specific example of the preferred rocess is, therefore, described.

As the oil to be employed in the process, I may use the gas oil fractions from petroleum oil and to such fractions, add from 5 to 10 per cent. of a metallic halide catalyst, such as aluminum chlorid, although other materials, such as, for example, ferric chlorid, may be used. These materials are placed in a still provided with a suitable type of agitator and the contents of the still heated while being agitated. As the temperature of the mixture increases, a temperature is reached where the low boiling point hydrocarbons begin to vaporize from the mixture. When a quantity of vapor or fixed gases begin to escape, the sys tem is regulated so as to impose upon the contents of the still a pressure above atmospheric. A desirable pressure has been found to be approximately 15 pounds above atmospheric, although much higher pressures have been used. The temperature employed upon the admixture may vary between wide limits, depending upon the type of petroleum being treated, the amount of refluxing taking place and the amount of aluminum chlorid used. I prefer to employ a temperature of about 50 to 7 0 F. higher than the temperature generally employed upon the same class of oils when carrying out the reaction at atmospheric pressure. Thus, for example, when operating upon a distillate which starts to distill under atmospheric pressure, at 450 F., the distillate rises to a temperature of from 515 F. to 580 F, after 5 or 8 hours of distillation. I prefer to maintain the contents of the still at approximately 600 F. during the distillation operation.

The lower boiling point hydrocarbon vapors, as they are formed, are passed to a reflux condenser of any desired type suitable for condensing the hydrocarbon vapors having higher boiling points than those desired in the distillate. This reflux condenser is preferably provided with a return line to the still for returning said higher boiling point hydrocarbons, together with any volatile compounds of aluminum chlorid that may be contained therein. No particular type of apparatus of this class is necessary for the process, there being various suitable stills, agitators, and reflux condensers well known in the art. The hydrocarbon vapors leaving such reflux condenser are thereafter condensed. Preferably, a thermometer is placed at the vapor outlet from the reflux condenser, in order to control the end boiling point of the hydrocarbon vapors leaving the system. \Vhen it is desired to produce U. S. motor grade gasoline, for example, the temperature of the vapors leaving the reflux condenser is around 300 F. luring the entire distillation when atmospheric pressure is used, and around 330 F. when a pressure 15 pounds above atmospheric is used.

The operation of my invention may be further described by referring to the attached drawingswhich diagrammatically illustrate one form of apparatus adapted to carry out my process. The reaction may be carried out in a still or converter 1 equipped with a horizontal agitator and shaft 2 adapted to mix the contents of the still. Charging stock may be supplied to the still through a valved inlet 3 from a source notshown, and the metallic halides may be introduced through a hopper 4: and a suitable valve 5 or it may be fed to said still in the form of a halide-oil magma or solution through the valved inlet 6. The still may be heated in any suitable manner, for example, by means of the fire box 7. An outlet valve 8 is provided to enable the reaction products or residue to be withdrawn from the still whether such residue is in the form of a liquid or cake. Vapors of lower boiling oils evolved within the still 1 may be discharged through line 9 into a reflux zone or condenser 10 of any suitable construction. As shown the reflux condenser is equipped with a cooling oil 11 and a packing 12, the

intermediate oils condensed within said con-' denser 10 being returned to the still by means of line 13. Vapors from the condenser 10 pass through line 14 into a condenser 15 which may be water cooled as shown and the condensate discharged by means of line 16 into-a receiver 17. Fixedgasesevolved during the conversion are operated from the condensed low boiling oils in the receiver 17 by being allowed to escape through a valved outlet 18, while the low boiling oils may be sent to any other suitable storage or other process through the valved outlet 19. Pressure on the system is regulated by controlling valve 20 in line 18 and pressure gauges 21 and 22 may be used to ascertain the pressure. The temperature of the mixture within the still 1 is kept above the temperature at which abullition normally takes place by regulating the amount of heat supplied by the fire box 7 or other means, and such temperature may be observed by a thermometer or other indicating or recording device inserted as shown at 23. The temperature of the vapors discharged from the reflux condenser 10 into the final condenser may be observed by a thermometer 24.

During conversion or distillation of oils with a catalytic metallic halide so as to form lower boiling oils, a certain amount of fixed gas is produced per hour, this amount of fixed gas being constant at any given temperature of the oil-halide mixture employed. Simultaneously, however, the production of gasoline or other lower boiling fraction per hour is much greater near the start of a distilling or converting operation than at the end thereof. Every cubic foot of fixed gas produced entails a loss of low boiling oils but by my process however, the rate of the conversion is greatly increased and not only a larger quantity of lower boiling oil is produced per hour but the loss of low boiling oils in the fixed gas is materially reduced and the ultimate yield from a given quantity of charging stock is thereby increased.

As an example of the present invention, the following table will illustrate the comparative results between the process of the present invention operating at both superatmospheric pressure and at increased temperature, and a process operating at atmospheric pressure:

Pressure Atmospheric Atmospheric plus 15lbs.per sq. in.

Oil charged Heavy gas oil.-. Same.

Aluminum chlorid used per 7% 7% cent by weight.

Vaporoutlet temperature (ap- 300F. 330F.

proximately).

Still temperatures and Still Still distillate yield Yleld temp. Yield temp.

(1) At start of distln 457 F. 500 F.

(2) 5 hours after start 27. 2% 515 F. 61 0% 600 F (3) 8 hours after start". 31. 0% 530 F. 67 0% 600 F (4) 10 hours after start 32. 4% 531 F From the above table, it will be seen that with the atmospheric process, there is only 81 per cent. yield after 8 hours of distillation, whereas with the process of the present invention, 67 per cent. yield is obtained. It will also be observed that with the atmospheric process, there is only a very slight increase in the amount of yield obtained after 10 hours treatment over that obtained with 8 hours treatment, indicating the tremendous length of time it would be necessary with the atmospheric process to obtain a yield equivalent to that obtained by the process of the present invention in 8 hours. The yield with the atmospheric process after 8 hours of treatment was so slow as to substantially prevent the obtainment of a yield of over approxi vapor outlet temperature is such as to give- U. S. motor grade gasoline, the outlet temperature being slightly higher in the superatmospheric process on account of the increased pressure on the vapors.

The distillate from each of the above experiments when finished by washing with water and lye to remove hydrogen sulfid and the small amount of hydrochloric acid that is formed by the partial decomposition of aluminum chlorid by oxygen compounds, are found to be substantially identical. The distillate may be further processed by a light sulfuric acid treatment, if desired. Some fixed gases are always formed in the aluminum chlorid conversion process. These gases do not condense with the gasoline and are preferably discharged from the final condenser. The pressure upon the contents of the still is obtained and held constant by the use of a suitable valve to regulate the rate of discharge of these fixed gases.

The residual products that remain in the still after the treatment consist of oil that has not been converted and tarry or coke residue containing spent aluminum chlorid. It is generally advantageous to conduct the distillation for only such a period of time as will allow the removal of this aluminum chlorid, tarry residue in liquid form rather than solid residue. In the example of the process above given, the aluminum chlorid residue was removed as a liquid. While this feature of the present invention is valuable, it is not intended to entirely restrict the invention to this feature, inasmuch as the process may be carried out to such an extent that the residues must be removed as solids. In case the residue is removed as a liquid, the unconverted oil, which is not miscible with the tarry residue can be separated therefrom and recharged to the still or otherwise employed.

It is also possible to conduct the process of the present invention continuously. This is carried out by the continuous charging of fresh aluminum chlorid and oil to the still and the continuous withdrawal of aluminum chlorid residue therefrom.

It is understood that while aluminum chlorid has been herein described as the catalyst of the process, various other metallic halides, such as ferric chlorid and the like, might be employed as the catalyst and the invention is not limited to the use of aluminum chlorid but embraces metallic halides in general.

I claim:

1. A process of converting petroleum oils into relatively lower boiling point oils, which comprises contacting said petroleum oils with anhydrous aluminum chloride catalyst in a distilling zone at superatmospheric presi i-e anhydrous aluminum chloride catalyst in a sure sufiicient to maintain the main partof the still unconverted oils in liquid phase but insufficient to prevent vaporization of the produced lower boiling point oils, While supplying sufiicient heat to the admixture to vaporize said produced lower boiling point oils and maintain the admixture at about 50 to F. higher than the temperature of ebullition of the admixture at atmospheric pressure.

2. A process of converting petroleum oils into relatively lower boiling point oils which comprises contacting said petroleum oils with anhydrous aluminum chloride catalyst in a distilling zone at superatmospheric pressure sufficient to maintain the main part of the still unconverted oils in liquid phase but insufficientto prevent vaporization of the produced lower boiling point oils, while supplying suflicient heat to the adm xture to vaporize said produced lower bollmg polnt oils and maintain the admixture at about 50 to 70 F. higher than the temperature of ebullition of the admixture at atmospheric pressure passing the vapors to a dephlegmating zone while maintaining the temperature of the vapors discharging from said dephlegmating zone suficient to permit escape of substantially only the desired low bo1l1ng point oils, and returning the reflux from said dephlegmating zone to said distilling zone.

8. A process of converting petroleum 0113 into relatively lower boiling point oils, which comprises contacting said petroleum oils with distilling zone at superatmospheric pressure sufficient to maintain the main part of the still unconverted oils in liquid phase but insufiicient to prevent vaporization of the produced lower boiling point oils, while supplying suflicient heat to the admixture to vaporize said produced lower boiling point oils and maintain the admixture at about 50 to 70 F. higher than the temperature of ebullition of the admixture at atmospheric pressure, while substantially preventing vaporization from said distilling zone of the anhydrous aluminum chloride catalyst.

4. A process of converting gas oil distillate of petroleum oils into lower boiling point oils suitable for gasoline, which comprises contacting said gas oil distillate with anhydrous aluminum chloride catalyst in a distilling zone while maintaining on said distilling zone a superatmospheric pressure sufficient to maintain the main part of the unconverted gas oil distillate in liquid phase but insufiicient to prevent the vaporization of the produced lower boiling point oils, while supplying sufiicient heat to vaporize said produced lower boiling point oils and to maintain the temperature of the admixture in the dis tilling zone at 550 to 620 F.

5. A process of converting gas oil distillate of petroleum oils into lower boiling point oils suitable for gasoline, which comprises contacting said gas oil distillate with anhydrous aluminum chloride catalyst in adistilling zone while maintaining on said distilling zone a superatmospheric pressure sufficient to maintain the main part of the unconverted gas oil distillate in liquid phase but insufiicient to prevent the vaporization of the produced lower boiling point oils, while supplying suitficient heat to vaporize said produced lower boiling point oils and to maintain the temperature of the admixture in the distilling zone at 550 to 620 F, while substantially preventing vaporization of the anhydrous aluminum chloride catalyst.

6. A process of converting gas oil distillate of petroleum oils into lower boiling point oils suitable for gasoline, which comprises contacting said gas oil distillate with anhydrous aluminum chloride catalyst in a distilling zone while maintaining on said distilling zone a superatmospheric pressure sufficient to maintain the main part of the unconverted gas oil distillate in liquid phase but insutlicient to prevent the vaporization of the produced lower boiling point oils, while supplying sufficient heat to vaporize said produced lower boiling point oils and to maintain the temperature of the admixture in 9 the distilling zone at 550 to 620 F., passing the vapors to a dephlegmating zone while maintaining the temperature of the vapors discharging from said dephlegmating zone suflicient to permit escape of substantially only the desired lower boiling point oils and returning the reflux from said dephlegmating zone to said distilling zone.

Signed at San Francisco, California, this 5th day of August, 1926.

WVILLIAM H. SHIFFLEB.

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