US1822861A - Art of converting hydrocarbon oils - Google Patents

Description

Patented Sept. 8, 1931 PATENT OFFICE LOUIS BURGESS, OF ROSELLE, NEW JERSEY ART OF'GONVERTING HYDROCARBON oILs Application filed April 13,

This invention relates to a method for converting high boiling hydrocarbon oils into low boiling hydrocarbon oils by heating such oils, and more particularly by heatingsuch 6 oils in contact with aluminum chloride at a temperature below the boiling point of such oils, and is a continuation in part of my prior copending application, Serial No. 482,401,"

filed July 5, 1921, entitled Art of converting 10 hydrocarbon oils.

It has been known for sometime that hydrocarbonoils of the class described could be converted into low boiling oils by heating in contact with aluminum chloride. However,

in the past it has never been found possible, as far as I know, to obtain better than 85 per cent of the oil charged as liquid products while obtaining substantial quantities of low boiling oils; the other 15 per cent represents losses in the form of gases, and cokey residues.

It is an object of this invention to provide a method for eliminating or greatly reducing the losses occurring through the formation of gas and cokey residues and increasing the yield of liquid products while maintaining or improving the yield of low boiling point oils.

It is a further object of this invention to provide a method whereby a still may be operated to convert high boiling oils into low boiling oils of exactly the gravity desired,

avoiding the losses incident to the production of distillate of gravity either greater or less than that desired.

It is still a further object of this invention to provide a method whereby a still may be operated indefinitely in a condition of temperature equilibrium, continuously evolving distillate of the desired gravity, and continuously receiving fresh oil to replace that converted.

Still other objects and advantages of my invention will be apparent from the specification.

The features of novelty which I believe to be characteristic pf my invention are set forth with particularity in the appended claims.

' My invention itself, however, both as to its fundamental principles and as to its particular embodiments will best be understood by 1927. Serial No. 183,285.

reference to the specification and accompanyin drawings, in which i igure 1 is a diagrammatic View partly in section of apparatus suitable for carrying out my invention.

Figure 2 is a section on the lines 2-2 of Fi ure 1.

igure 3 is a section on the lines 33 of F i ure 2.

igures 4 and 5 are charts of typical runs made according to my invention.

In the past, processes of the sort to which my invention relates, have been carried out in a largely empirical manner and the effect of factors governing the reactions taking lplace in the still, as a result of which highoiling hydrocarbon oils are converted into low-oiling hydrocarbon oils, has been little understood, at least as concerns the efficiency of the processes.

In the various modifications of the prior art processes, the maximum yield of liquid products is about 85 per cent of the oil charged when substantial quantities of gasoline are produced, and usually such-efficiency is not obtained. As pointed out above, undesired cokey residues are formed in the still, gases are evolved and the gravity of the distillate may at any instant, vary widely from the value desired. I

I have discovered that those losses may he almost entirely eliminated, or at any rate,-reduced very considerably, and conversion efficiencies as high as 95 to 99 per cent obtained in practice when the process is carried out in accordance with my invention.

Ihave discovered that under certain conditions which will be hereafter set forth in greater detail, it is possible to operate ata constant temperature equilibrium for an indefinite period, supplyingto the st1ll highboiling hydrocarbon oils to take the place of those converted, and supplying to the st1ll a continuous, uniform supply of aluminum chloride to maintain a condition ofconstant' catalytic activity within the still, while the still continuously evolves distillate of a substantially constant and unchanging gravity of the value desired.

The temperature of equilibrlum may be different for distillates of different gravity and for different types and grades of highboiling oils: however, it will'be found that, with any type of high-boiling oil and any gravity of distillate desired, there is one temperature at which the process is carried on at maximum conversion efiiciency, and at which temperature the still may be operated for a practically indefinite length of time at a temperature which remains constant within the limits of experimental error, evolving distillate of a gravity likewise constant within the limits of experimental error.

Referring now more particularly to Figure 1, 5 indicates a suitable still mounted upon a furnace setting 6. The conversion in the presence of catalytic aluminum chloride is carried on in the still 5, which is provided internally with a stirrer 7, preferably having the form of a rectangular frame, mounted upon vertical shaft 8 provided with a suitable driving gear 9. The bottom member of the stirrer 7 indicated by the numeral 10,.has pivoted to its lower edge a number of, dragging scrapers 10a, those on opposite sides of the central -shaft 8 being disposed in opposite directions. These scrapers are so disposed as to cover substantially ,the entire bottom surface of the still 5 in the rotation of thescrapers; and the still 5 is provided at its bottom with an outlet valve 11 of the poppet type fitting into a suitable seat in the bottom of the still, and is so arranged that its upper surface is flush with the bottom of the still. The stem 12 of the valve 11 is provided with a rack operable by means of gear mounted on shaft 13 operated by the hand wheel 14. The outlet valve gear is surrounded and supported by a discharge pipe or casing 15, which opens into the receptacle 16 r a gate valve 17 is provided to close off the receptacle 16 from the discharge pipe 15.

The still is provided with inlet pipe 18 which preferably opens into the still along its bottom and through which oil, or catalytic aluminum chloride, or both, may be introduced into the still. This pipe communicates with an aluminum chloride generator 19 which may be charged with aluminum or suitable aluminiferous material for the production of aluminum chloride.

The generator 19 may be heated by any sultable device for example the fuel burner 20, and chlorine or hydrochloric acid gas may be introduced thereinto throughpipe 21. Oil

may be suppliedto the inlet pipe 18 by any suitable means.

In the device illustrated, this consists of an annular casing 22 surrounding the. inlet pipe 18 through which the communicating perforations or apertures 23 are provided,

if desired, and the oil may be pre-heated before introduction. In the form of apparatus illustrated, the fresh oil may be introduced by valved pipe 24 into the discharge pipe cas-' ing 15 from the still, the valve 11 and 17 being closed. It then passes out of the discharge pipe 15 through valved pipe 25, preheater 26 and pipe 27 intothe annular casing 22, from which it enters the inlet pipe 18. The vapors from the still 5 pass off through the vapor line 28 to water cooled tubular condenser 29,

shown diagrammatically, from which condensate and uncondensed gases pass out through pipe 30. The tubes of this condenser are vertical and in case sludge is carried over into the vapor line during the run, it flows stock may likewise be an oil of the character of kerosene; for example, having an initial boiling point. of 350 to 360 F. and a dry point of 522 to 550 F. It will be understood that other types of oils may be used.

- Having described the apparatus used in practicing my invention, I will now particularly distinguish between the prior art and my new method of operation. When operating according to the prior art, as distinguished from operation according to my invention, the still is first charged with a quantity of oil to be converted and a charge of aluminum chloride suflicient for substantial conversion, and usually in the proportion of 5 to 7 per cent by weight of the oil-to be converted. In heating the oil, distillation begins at a temperature of about 356 F. in the oil, and a very light distillate, which may have a gravity of 70 B. and in some cases as high as 80 to 85 B., together with considerable gas is first produced. The rate of distillation thereafter is maintained by gradu ally increasing the temperature of the oil in the still, and this is accompanied by a gradual diminishing of B. gravity of overhead distillate. The progressive rise in temperature of the oil undergoing distillation in contact with aluminum chloride and the concomitant dimunition in B. gravity of the distillate produced will be apparent from the results of a run made with gas oil stock and 7% by weight of anhydrous aluminum chloride reported on page 5 of U. S. Patent 1,322,762

to E. B. Cobb. The gravity temperature re-- lationships appear indetail in Table A given on page 5 of said patent. By reference to page 4 line 94 to 95 of the same patent, it

will be noted that the distillate initially produced from the chloride distillation may have a gravity of as high as 80.7 Be.

If the temperature is held constant at any point, the evolution of distillate will gradually fall off and shortly cease altogether, un-

, less the temperatures are maintained sutliciently' big to create a distillate by pyrogenic decomposition independentlyof the aluminum chloride. In other wordstrue aluminum chloride distillation with a single or intermittent charge of aluminum chloride can only be maintained by gradually and continuously elevating the temperature of the oil in contact with the aluminum chloride or aluminum chloride hydrocarbon compounds. The elevation of temperature and the concomitant diminution in aluminum chloride activity results in a continuously diminishing gravity of distillate. This cannot be efl'ectively controlled by the use of refluxes or other rectifying devices for the reason that the runback or oils returned by the reflux, although of higher boiling point than the vapors passing overhead from the reflux, are of lower boiling point than the body of oil in the still and boil out of the still without materially reacting with the aluminum chloride present.

These intermediate oils operate therefore to transfer heat from the still to the reflux and continue to accumulate until the heating devices available cannot further raise the temperature of the oil in the still and aluminum chloride cracking ceases, or the reflux is unable to take care of the total quantity of vapor, and a drop in the Baum gravity of the overhead distillate is experienced. When operating underthe prior art, therefore, the gravity of stock produced inevitably varies over considerable limits. I have discovered that production of a numerically higher Baum gravity (viz. a lower specific gravity) of distillate than the average required, as it occurs at the commencement of distillation, isresponsible for the excessive production of gas and cokcy residues and excessive consumption of aluminum chloride.

The production of a numerically lower Baum gravity (viz. a higher specific gravity) of distillate than the average required, as it occurs in the later stages of distillation, results in a diminished industrial efficiency and incomplete'return on capital investment. Moreover, if a new batch of chloride is charged at'temperatures substantially above the sublimation temperature about 360 F.), it volatilizes so rapidly that. it does not combine with the oil,'and largely escapes and is lost to the'reaction. To overcome this difficulty, it is usual to permit the still to cool down before adding a new charge of aluminum chloride. n

This also involves a loss of time and return on the capital investment.

In my process, as distinguished from the still.

prior art, the still is charged with a quantity of the oil to be converted. Market conditions, such as the relative price of gasoline, kerosene and charge stock, and the amount of-loss and aluminum chloride consumption incident to the production of distillate of any desired gravity, indicate the desired composition of distillate for which to operate. If as a result of previous runs on the particular oil, it has been ascertained at what temperature this oil will in contact with aluminum chloride, produce the desired composition or gravity of overhead distillate, the oil may be raised immediately to that temperature. If this temperature has not been ascertained, a small amount of aluminum chloride, say from 1 per cent to 3 per cent, is added, not primarily to produce substantial conversion, but by the production of some distillate to show when the desired temperature is obtained.

When the temperature has been obtained by either of thesemethods, I commence feed ing aluminum chloride to the contents of the still, either in solid form or in the form of vapor or aluminum chloride hydro-carbon compounds. This aluminum chloride is added at a substantially constant and uniform rate, directly proportional to the rate of consumption, and in general will not exceed 2% by weight per hour of the oil present in the still at any time. It is not intended inthis manner to build up a supply of aluminum chloride for subsequent reaction. Aluminum chloride is not a complete catalyst, but is continuously withdrawn from useful functioning as a consequence of side reactions and the formation of compounds which are stable at the particular temperature of operation.

The'rate of addition of aluminum chloride is suflicient to compensate for this consumption and to maintain a substantially constant catalytic activity in the still: Whereas under the old process, a large quantity of aluminum chloride passes of reactions extending over a considerable period of time, it will be readily understood that in the present process any given increment of aluminum chloride passes in a relatively short interval of time through a similar sequence, and under conditions which are substantially unchanging and may be more preci'sely controlled. By reference to Example 4 hereafter, it will be seen that the rate of addition with a gas oil charge held at a temperature of 219.59 C. yielding a distillate of 45.6" B'. gravity and at a uniform rate of about 9.7 liters per hour, the rate of addition is equal to 4.12% by weight of the distillate produced and about 47 hundredths of one per cent by weight per hour of the oil in the through a certain sequence By' reference to Example N0. 3, it will be chloride is equal to substantially 1.74% by weight of the overhead produced and about 36 hundredths of one per cent by weight per hour of the oil in the still.

As a result of gradual changes in the composition of the oil in the still, and as a result of selective attack by the aluminum chloride and the gradual diminution in total volume, the temperature at which the mass of oil will produce a distillate of the desired gravity will increase until final equilibrium is reached.

In my preferred method of operation. I feed in the aluminum chloride in the manner just described, and also feed in oil at the rate at which it is consumed, viz: in quantity sufficient to substantially compensate for the amount converted into distillate, gas and sludge. This feeding of oil is preferably started as soon as distillate begins to be evolved. When so operating, the temperature at which the oil produces a distillate of the particular gravity desired will change slightly as a result of selective attack by the aluminum chloride, but this is clearly not due to any diminution in total volume. The change mentioned can be compensated for by slightly changing the temperature of the oil in the still in contact with the aluminum chloride. At the end of several hours of operation, those products which decompose preferentially become proportionately diminished in concentration, while those which decompose with the least readiness increase in concentration until a condition of true statistieals or dynamic equilibrium is produced in which the decomposition of the hydrocarbons takes place in the same proportion in which they are supplied to the still. Petroleum oil, that is crude petroleum or a distillate separated therefrom by fractionation, consists of various compounds and grou sof compounds, such as, for example, para ns, naphthenes, olefines and aromatics. The individual compounds in any group and the proportionate amount by volume of any particular group depends upon the source and manner of preparation of the particular stock. These various compounds and the .groups of homologous compounds manifest different degrees of reactivity with anhydrous aluminum chloride and different cracking rates in the presence thereof. I have found, however, that by conducting a substantially isothermal distillation, supplying oil to the still at the rate at which distillate is evolved and adding chloride in a uniform manner to maintain and control the rate at which distillate is produced, I can build up in the still such relative proportions of the various reacting constituents that the decomposition of these various constituents in any given time is substantially equal to the amount of these several constituents introduced with the feed oil. This is a condition of equilibrium, and while it does not represent a true chemical equilibrium in the sense in which this term is employed in physical chemistr there is an equilibrium of the ratios o. the various reacting components. This is'shown by the fact that once this condition has been attained, the composition of the above distillate remains constant throughout the subsequent conduct of the distillation, and samples of the oil in the still withdrawn at intervals show a practically unvarying composition. Inasmuch as this represents an equilibrium of relative numbers or ratios of the reacting components, I have referred to it as a statistical equilibrium.

When this point is reached, the process may then be continued indefinitely without further change in the composition of the oil in the still, the composition of distillate, or still temperature. The temperature of the oil in the still is thereafter held substantially constant and the composition of the overhead distillate continues substantially unchanged. I have, moreover, discovered that when this condition is arrived at, the rate of distillation becomes a direct function of the rate at which aluminum chloride is supplied, and may be controlled in this manner. I may, in this manner, produce any desired rate of evolution of distillate, say from 1 per cent per hour by volume of the oil in the still up to 20 per cent or more, the only limiting factor being that the rate of conversion must not be so rapid as to carry unconverted charge oil over mechanically from the still.

For introducing the quantities of aluminum ehlorlde necessary to malntain hlgh rates of distillation or the large quantities necessary in commercial apparatus, I may employ a plurality of ducts communicating with the oil in the still. For example, pipe 18 may communicate with the still 5 at a number of points distributed around the wall thereof, at or near the bottom of the still. In this way, better absorption of the incoming aluminum chloride can be obtained than with one only. The uniform and continuous production of distillate may thereafter be continued, for days if desired. Under the pr or art practice, hydrocarbon aluminum chloride residues in the still tend to pass into granular cokey forms, which impede or completely stop the action of the stirrer; but under my method, they are at all times of a smooth and. fluid or semi-fluid consistency. Whenever these residues have accumulated to a point at which removal is desired, the operation of a stirrer is stopped. The residues are permitted to stratify and settle out of the body of the oil in the still, and in a few minutes may be Wholly or partially withdrawn and the operation resumed without lowermg the temperature of thestill contents. v

The addition of oil may suitably be carried out in the. device illustrated, by passing 1 the oil to be fed into the still during the run .through the pipe 24, the outlet valve casing 15, the pipe 25, and pre-heater 26, and the pipe 27 into the inlet pipe 18.

The proportion of oil fed during the run is regulated in accordance with the amount of distillate formed and known or estimated amount of loss to gas and sludge so 'as to maintain a substantially constant volume of oil within the still, and preferably this is maintained constant throughout the entire run and to the end thereof.

The feed oil in the casing 15 is maintained at a pressure in excess of the pressure of the oil within the still on the poppet valve, and the contents of the still, therefore, cannot leak past the poppet valve 11 during the run.

The supply of aluminum chloride may be terminated shortly before the end of the run, in order to utilize all of the aluminum chloride within the still. During this period of operation, the equilbrium is upset since the catalytic activity of the aluminum chloride is decreasing and the still temperature is required to be raised, which is accompanied by a decrease in the Baum gravity of the distillate. This particular phase of the operation corresponds to the prior art practice.

The equilibrium temperature for the conversion of paraflin base oil to a distillate of 60 to 50 B. gravity may be.from480 F. to 600 depending upon the character of the oil desired, but it will be understood that with: any particular oil and distillate of specified gravity the equilibrium temperature should be reached within about 8 to- 12 hours after the start of the run, depending on the rate'atwhich distillation is conducted and that thereafter, if the temperature ismaintained constant within the limits of experimental error, the distillate will have a Baum gravity constant within the limits of experi mental error. The equilibrium temperature may lie between 356 and 440 F. for the production of a similar distillate from an oil of the character of kerosene. The oil residue remaining in the still at the end of the run, mayhave a specific gravity substantially the same as or less than the, original oil charge. This residue may likewise be subjected to the conversion process under the same conditions as the original material.

The following examples further illustrate the operation of the process:

Example 1.The still was charged with 100 parts by volume of paraffin base gas oil, having a gravity of about 33 B. and with about three per cent of anhydrous aluminum chloride. The run occupied 12% hours, the distillate being formed shortly after the beginning of the run. The total distillate formed was 80 parts, the rate of formation being approximately six per cent of the original charge per hour during the entire run. The average gravity of the distillate was 52 B. During the run 72 parts of gas oil were fed into thestill at a substantially uniform rate corresponding to the rate of'production of distillate, introduction of feed oil being stopped approximately one hour before the end of. the run. A quantity of aluminum chloride in vapor form was sup' lighter than the original oil treated, and

therefore having a density lower than the original oil charged.

Ewample 2.-The oil treated in this case was a naptha bottom from pressure distillate, having a gravity of about 428 B. 100 parts of this oil were charged into the still, and an additional 57 parts were fed into the still during the run, the rate of feed of fresh oil being somewhat lower than the rate of formation of distillate. Additional aluminum chloride was fed into the still at a substantially uniform rate during the run, the amount so fed being about 220% of the amount originally present therein. A running .temperature of about 356 F. was attained shortly after the beginning of the run and a temperature of between 356 and 365 F. was maintained during the remainder of the run, the gravity of distillate varying in this period from 53 B. to 575 B.; parts of distillate were obtained having an average gravity of about 51.9 B. The residue amounted to 73 parts having a density materially lower than that of the original oil charged.

In the last example given above, the relatively high proportion of catalyst required was due to the low temperature at which the run was carried out, necessitated by the relatively low boiling point of the oil. A higher efficiency of catalytic aluminum chloride is obtained in treating such an oil by operatlng at a higher temperature, in which case, however, unconverted oil distills over with the converted products.

Example 3.-The oil treated in this case was Mid-Continent kerosene distillate. 100 parts of this oil were charged into the st1ll at the start, and 500 additional parts were fed into the still during the run, which occupied a total time of 40 hours. 1,356 grams of aluminum chloride were fed to the still after two hours of operation and thereafter additional aluminum chloride was fed in at a substantially uniform rate during the run, the amount so fed being 7,924 grams. An equilibrium temperature of 255 C. was attained between 12 and 14 hours after the beginning of the run.

From the 16th hour of the run to the th hour inclusive, the difference between the average temperature and the temperature at any instant, or what I term the temperature deviation, did not exceed 4 F.; and the average temperature deviation was 1.8 F. During this period the equilibrium gravity of the distillate was 47 .0 B., and the greatest deviation from the equilibrium gravity of the distillate was 0.7 0 B.; the average deviation was 0.4 B.- During the run 512 parts of distillate were evolved, and 70 parts of gas oil remained in the still at the termination of the run. The losses amounted to 3 per cent of the total charge and the conversion efliciency was therefore 97 per cent. The results of this run are set forth graphically upon the chart shown in Figure 4.

Ewwmple 1;.The oil treated in this case was a charge of 100 parts of oil having a gravity of 42 B. cut from pressure still distillate. 329 additional parts of oil were fed during the run which continued for 36 hours. 1350 grams of aluminum chloride were charged initially, and a total of about 12,050 grams additional aluminum chloride were fed into the still at a substantially uniform rate during the run. Equilibrium was obtained in about 12 hours, the equilibrium temperature being 219.5 C. The maximum temperature deviation of the still contents at any instant after the attainment of equilibrium, was 35 F., and the average deviation was 1.6 F. The average gravity of the distillate evolved was 45.6 B.; the maximum deviation of the gravity of the distillate was 04 B.; the average deviation was 0.2 B.; the distillate evolved was 425.3 parts; the oil recovered from the still 95.6 parts. The losses amounted to 1 per cent; and the conversion efiiciency was therefore equal to 99 per cent. The results of this run are shown graphically in the chart. of Figure 5.

When running under those processes above described in which the Baum gravity of the distillate is maintained by suitable additions of aluminum chloride throughout the run, according to my invention, although the tank average Baum gravity of the distillate may be the same at the end of the run as under the prior art, the results are superior. The elimination of the excessive gas and residue losses and the sustained efliciency resulting from the addition of the aluminum chloride at the proper rateand the maintenance of equilibrium temperature and equilibrium gravity of the distillate, results in a much larger yield of liquid-products. The maximum yield of liquid products when operating under the prior art methods for the production of substantial quantities of gasoline, does not exceed 85 per cent and is usually less than this, whereas when the process is carried out according to my invention, the vield of liquid products is usually better than 95 per cent. According to my invention, the still temperature may be so controlled as to maintain the Baum gravityof the distillate substantially constant within the limits of experimental error throughout the run: or the Baum gravity of the distillate may be permitted to vary within certain limits without departing from the spirit of my invention, it being borne in ing hydrocarbon oilsinto low boiling hydrocarbon oils by heating said oils in contact with aluminum chloride at a temperature less than the boiling point of said high boiling oils, which comprises adding to the oils, before heating materially less aluminum chloride than that required to produce the desired quantity and quality of distillate, bringing the still contents to reacting temperature. maintaining the temperature of the still contents constant, adding additionaloil to maintain the volume of still contents substantial ly constant, and adding additional aluminum chloride at a uniform rate, to produce at any instant after equilibrium distillate of the gravity desired to limit the losses to not more than 4%, the amount of chloride added during any interval being substantially equal to that reduced to inactivity during said interval at the temperature maintained whereby a substantially constant catalytic activity is maintained. R

2. Process of converting petroleum oils to lower boiling point products, which comprises maintaining a body of petroleum oil in contact with catalytically active aluminum chloride at a temperature at which distillate vapors are evolved,'maintaining the temperature of said body substantially constant, conducting away the evolved distillate .vapors, adding fresh oil to said body at a rate sufficient to maintain the volume thereof substantially constant, and adding to said body catalytically active aluminum chloride at a substantially continuous and uniform rate, the amount of chloride added during any interval being substantially equal to that reprises maintaining a body of petroleum oil in contact with catalytically active aluminum chloride at a temperature at which distillate vapors are evolved, maintaining the temperature of said body substantially constant, conducting away the evolved distillate vapors,

adding fresh oil to said body at a rate sufiicient to maintain the volume thereof substantially constant, and adding to said body catalytically active aluminum chloridecat a substantially continuous and uniform rate sustained throughout the major part of the period of distillation, the amount of chloride added during any interval being substantially equal to that reduced to inactivity during said interval at the temperature maintained whereby a substantially constant catalytic activity is maintained.

4. Process of converting petroleum oils to lower boiling point products, which comprises maintaining a body of petroleum oil in contact with catalytically active aluminum chloride at a temperature at which distillate vapors are'evolved, maintaining the temperature of said body substantially constant, conducting away the evolved distillate vapors,

- adding fresh oil to said body at a rate sufficient to maintain the volume thereof substantially constant, and adding to said body catalytically active aluminum chloride at a substantially continuous and uniform rate, not

exceeding substantially 2 per cent by weight per hour of the weight of the oil undergoin conversion, the amount of chloride adde during any interval being substantially equal to that reduced to inactivity during said interval at the temperature maintained whereby a substantially constant catalytic activity is maintained.

5. Process of converting petroleum oils to lower boiling point products, which comprises maintaining a body of petroleum oil in contact with catalytically active aluminum chloride at a temperature at which distillate vapors are evolved, conducting away the evolved distillate vapors, adding oil'to said body at a rate suificient to maintain the volumethereof substantially constant and adding to said body a relatively small and substantially continuous supply of aluminum chloride, holding the said body of oil at a temperature at which distillate of a predetermined gravity is evolved, modifying said temperature from time to time to the extent necessary to compensate for progressive variation in the composition of the said body of oil and to maintain the gravity of the distillate evolvedsubstantially constant until an equilibrium mixture of thevarious components of said body of oil is produced which does not undergo further variation, there after continuing the distillation at a substantially constant temperature with the continuous production of distillate of a predetermined gravity, adding thereto oil to maintain the volume of the body substantially constant and catalyst at a uniform and sustained rate, the amount of chloride addedduring any interval being substantially equal to that reduced to inactivity during said interval at the temperature maintained whereby a sub stantially constant catalytic activity is maintained.

6. Process of converting petroleum oils to lower boiling point products, which comprises maintaining a body of petroleum oil in contact with catalytically active aluminum chloride at a temperature at which distillate vapors are evolved, conducting away the evolved distillate vapors, adding fresh oil to said body at a rate suflicie'nt to maintain the volume thereof substantially constant, maintaining the temperature of said body substantially constant and adding catalytically active aluminum chloride to said body at a uniform and sustained rate throughout the major part of the period of distillation ina plurality of spaced streams communicating with the said body, whereby interaction between the added catalyst and the said body is facilitated and better absorption of the catalyst is enhanced, the amount of chloride added April, A. D. 1927. a

' LOUIS BURGESS.

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