US1672339A - Distillation of oils with catalysts - Google Patents

Description

June 5, 1928.

G. L, PRlcHARD ET AL DISTILLATION OF OILS WITH CATALYSTS 2 Sheets-Sheet l Filed Nov. 28. 1921 ...UNA

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June 5, 1928. 1,672,339`

G. L. PRICHARD ET AL DISTILLATION OF ILS lWITH CATALYSTS Fiied Nov.28, 1921 2 sheets-sheet 2 Patented June v5, 1928.

GEORGE L. PRICHABD AND HERBERT HENDERSON, OF PORT ARTHUR, TEiXKAS, AS-v SIGNORS T0 GULF REFINING COMPANY, 0F PITTSBURGH, PENNSYLVANIA, A COR- PORATION OF TEXAS.

DISTILLATION OF OILS WITH CATALYSTS.

Application led November 28, 19241. Serial No. 518,197.

This inventionrelates to distillation of oils With a catalyst; and it comprises an improvement in the distillation of petroleum oils with a catalyst, such as anhydrous aluminum chlorid, for the urpose' of producing oils of lowered` boiling point, wherein a body of oil and catalyst (aluminum chlorid) is established and maintained at a temperature sulicient to cause free ebullition with production of vapors and the catalyst is Withdrawn from the bath prior to its complete exhaustion or conversion into a coky sludge, delivered to a suitable heater device and is then exposed to a temperature at which the catalyst will volatilize, the vapors of the catalyst so formed (and any oils withdrawn with it) being recovered in any suitable way but advantageousl by returning to said bath; all as more ully hereinafter set forth and as claimed.

As is well known, it is possible to produce oils ,of lowered boiling point by distilling high boiling petroleum oils with catalysts usually anhydrous reactive chlorids, bromids, etc. such as iron chlorid, zinc chlorid and, particularly, anhydrous aluminum chlorid. This fact is utilized in the production of gasoline and similar products from higher boiling oils, suoli as gas oil, kerosene, etc. In this operation success depends upon attention to many minutiae. Anhydrous aluminum chlorid (the catalyst now extensively used) is not particularly soluble in oils, hot or cold, and when a small amount of aluminum chlorid, say, 5 per cent, is added to a petroleum oil, t-he aluminum chlorid melts down with a portion of the oil to form a heavy oily liquid underlying therest of the oil. When this heavy liquid is kept stirred through the rest of the oil and the mixture is heated, at a certain temperature, which is often below they natural boiling point of the oil under treatment, the mass enters into free ebullition withproduction of vapors of oily of a lowered boiling point, Usually, the bath of oil and` aluminum chlorid is kept replenished by additions of fresh .oil in proportion to the formation of vapors. The operation may be continued in this way until the aluminum chlorid loses its activity .and is converted into a relativelyy inert coky or sludgy mass. At this time it is removed and replaced by fresh chlorid. Ordinarily, the proportion of aluminum to a suitable treatment to recover aluminum.'

chlorid in an activevr condition for reuse.

v 1,672,339 UNITED STATES PATENT-OFFICEf- Ordinaril it is placed in a retort and heated, distilhng off first the oil which is present and then the aluminum chlorid. Recovery may be facilitated and aided by the use of a little chlorin or chlorin containing gas such as hydrochloric acid, 4

In the described' operation, there isv considerable loss because of the changes undergone by p sidues 1n handling. And in the distillation process described the aluminum chlorid is not utilized to yits fullest extent, it becoming masked so to speak by carbon when the process is carried so far as to leave a coky or sludgy residue. y

Aluminum chlorid is verysensitive to the action of moisture by which it is hydrated and decomposed, giving alumina and, if the mass is hot, vapors of HC1. Hydrated aluminum chlorid has no catalytic activity upon oils and cannotbe preconverted to the anhydrous form. It is very diiiioult to avoid exposure of the aluminum chlorid to damaging amounts of water -vapor 1n, transferring the sludge from the stills to the recovery apparatus.

'In the production of gasoline, etc., there is a progressive change in the characteristics of the aluminum chlorid in the still. Atrst it is, as stated, a heavy viscid liquid the aluminum chlorid in the re- 'nsI and finally it becomes a tarry or coky mass. y

oil body and. the thickened aluminum chlo-y rid, ,or whether it be becauseof a real ldiv minutionin converting power, the factispas stated. y .Y v,

'.We have found that in the recovery there is much the same phenomenon-#the alumilos num chlorid is much more rapidly and easily recovered from the oily material in t-he earlier stages of distillation than from the thicker material of later stages; and we have found that this increased ease of recovery liquid prior to its reaching the asphaltic or coky consistency and be placed in a retort and distilled, the aluminum chlorid goes over With the oil vapors at a much lower temperature than would be necessary in recovering aluminum chlorid from an asphaltic or coky residue.

While We do not commit ourselves to any theory as regards the reason for this easier recovery, we may call attention to the fact that, as-stated, when aluminum chlorid 1s added to hot oil it melts down with a portion of the oil to a heavy liquid. This is apparently a combination of the oil and alumlnum chlorid. It is perhaps possible that during the progress of the distillation the character of the oil associated or combined with the aluminum chlorid progressively changes, and that in the exhausted aluminum chlorid the combination is with hydrocarbons of a more or less asphaltic nature; such a combination that aluminum chlorid distills from it with diiiculty.

By removing the aluminum chlorid sludge at an intermediate stage of exhaustion, it is of such consistency as enables its ready transfer through pipes to recovery apparatus without exposure to air. This precludes the material loss occurring inu the ordinary methods of handling.

The aluminum chlorid coming as vapors from the recovery apparatus is highly active and suited for reuse. In distilling this character of 1esidue,l1owever, the vapors of aluminum chlorid are ordinarily associated with oil vapors. The two may be condensed together to form a heavy, oily liquid like fes that originally formed in -the still. This liquid may be returned to the still. Or, the hot oil and aluminum chlorid vapors coming from the recovery apparatus maybe sent direct to a still operating with aluminum chlorid to take part in the operation of such still. In so doing, looked at in one way, the function of the recovery apparatus is largely that of elimination of coky and asphaltic hydrocarbons which would otherwise finally mask the activity of the aluminum chlorid in the still.

In the present invention we contemplate running the gasoline-making operation at high speed, using nothing but highly active aluminum chlorid. And we increase the amount of aluminum chlorid present above 10 per cent. Where the recovery apparatus has a direct vapor connection with the still, much of the aluminum chlorid is in cyclic circulation, passing from the still to the recovery apparatus and thence back; and the 10 per cent ligure refers merely to the amount in the still-to a proportion of 10 per cent of aluminum chlorid to the weight of oil in the still undergoing distillation. And by our method we may eliminate the formation offcoky residues in the stills.

In the accompanying drawings showing one form of a specific embodiment of our inventiomand illustrating an apparatus within the purview of our invention.

Figure 1 is a view partly in vertical section and partly in elevation;

igure 2 is a top plan view 0f Figure 1 an Figure 3 is-a segmental enlarged horizontal section through the `converter or still at the point of inlet of oil. e

ln the drawings, 1 indicates a furnace which may be divided into preheating compartment A and superheating compartment B divided by the bridge-wai 2. This furnace is preferably of fire-brick or the like 3 suitably insulated with kieselguhr or the like 4, and is provided with the oil and steam burner 5 or other heating means. The preheating compartment A comprises a pluralityof tubes 6, here shown as horizontal, through which the oil flows. Oil is admitted to the preheater by line 7 leading from vthe pump 8. From the preheater the oil fiows to the superheater compartment B in the tubes 9 located therein and from the tubes 9 the oil llows by means of line 10 to the still or converter to be described. When the material is to .be constantly circulated it is removed from the converter by line 11 and sent to the pump 8. We may use one or more heaters. The line 10 may be branched with the valved pipe 13 having the down pipe 14 extending near the bottom of the converter, and may also be provided with the valved branch 16 extending into the upper part of the converter preferably below the level of the contents.

The converter or still is indicated as a whole by 17. It comprises a steel or other suitable tank 18 covered with insulation material such. as kieselguhr, asbestos or the like 19 and is provided with a cone-shaped botbracket-s 27 and to the shaft at the top is' keyed beveled gear 28 meshing with the pinthe usual 5 per cent, giving as high as, say, ion 29 driven by pulley 30 and in turn driven by the belt or chain 31 leading to the motor 32. The shaft may be braced inside the still by the arm-s 33. The still or converter may be provided interiorly with the arms 34 between the paddle blades 35 carried by the shaft 23. Vapors of lower boiling hydrocarbon together with some aluminum chlorid and the combination of aluminum chlorid with higher boiling oils go to` the preliminary air cooled condenser 36 through vapor line 37, condensed products being backtrapped to the still through line 38. Vapors leaving the preliminary air cooled condenser 36 go to the final air cooled condenser 39, condensates therefrom returning to the ybacktrap line 38 by means of the line 40. The backtrap line 38 preferably leads below the level of the contents of the still. The air cooled condensers 36 and 39 are provided with thermometers 41 in order that the temperature of the vapors may be observed. In aluminum chlorid distillation processes the'temperature of the vapors leaving the final air cooled condensery should not be materially above 350O F., since at-and below that temperature -aluminum chlorid, and its compounds with.hydrocarbons, will condense and go back to the still, Whereas at a higher temperature they Will not condense, but will pass over with the vapors of lower boiling oils. From the final air cooled condenser vapors of lower boiling hydrocarbons flow by line 42 to the coils 43 in the water cooled condenser 44, suitably mounted by means of supports 45 upon the condenser box foundation 46. From the coils in the condenser the condensed lower boiling oils flow by means of line 47 to a storage tank past the liquid seal 48, any non-condensed gases escaping through the line 49- Aluminum chlorid and hi her boiling oil may be admitted to the stil or converter through the inlet 50.

.The converter at the bottom is provided with the offtake 51 from which the residual oil and aluminum chlorid may be with'- drawn. According to our process the aluminum chlorid is withdrawn with some oil before the activity of the aluminum chlorid is completely spent and it is sent by means of valved line 52 to the pipe 53 leading to the retort 54. This retort may comprise a steel or other suitable tank 55 mounted upon the furnace 56 which may be provided with the burners 57 and the stack 58. This retort constitutes the recovery apparatus. Volatile product-s leaving the retort by line 59 may go past the branch 60 into line 61 'leading to the still 17 preferably into the vapor space thereof. If desired the branch 60 may be used to send the volatile products from the retort to suitable condenser apparatus through line 62 and in certain stages of the operation when gases containing chlorin (HCl) are evolved, they may be sent by line 63 to suitable apparatus where the gases may contact with aluminous material for the manufacture of aluminum chlorid thereed aluminum chlorid and high boiling point o oil are pumped in through the charge line 50; the high boiling point oil carrying with it sulicient amounts of aluminum chlorid to equal, for instance, 10 per cent by weight of the total charge in the still. The oil or gas burner.5 in the furnace is then suitably regulated to heat the oil in the tube furnace to the required'. temperature and wedeliver the oil through circulating pipe 10 advantageously to a point near the bottom of the converter by line 14. The stirrers 35 are then operated to keep the mixture Iin the unit or converter wellagitated. The hot oil and vapor delivered to the converter at the bottom pass up through the body of the mixture and released vapors pass through the Vapor line 37, thev temperature in the converter being controlled so that the vapor leaving the final air cooled condenser shall not materially exceed 350 F. as registered by vthe thermometer 41 in the line leading from such condenser. The vapors from this point go through the vapor line 42 into the condenser coil 43 and condensat'es go past t-he gas seal 48 through line `47 to the run-- ning or storage tank. The noncondensible gases released through pipe 49 go to an absorption or compression plant.

After the converter -or still has been operated to a point where gasoline to the extent of from {th to 5 gallons of gasoline perpound of aluminum chlorid in the converter has been taken off, the circulation of oil" passing through pipe 10 and entering the bottom of the converter by line 14 is then changed by closing the valve on line 13 (Flgure 3) and openin valve or line 15, thus delivering the circu ating oil through line 16 to the top of the magma unit. The stirrers are either slowed down or stopped entirely and 25 per cent more or less of the sludge in the converter isdrawn off through line 51 into the retort 54 by opening suitable valves on the line. After this amount of sludge has been drawn into the retort valve on line 13 will be opened and valve on line 15 will be closed, again discharging the circulating oil to the bottom of the converter through line 14. The stirrers 35 are? again j put in operation or speeded up and an amount of aluminum chlorid charged into the unit with` high boiling point oil through the line 50, such amount being equivalent to the amount of aluminum chlorid drawn off in the sludge into the retort 54. This keeps the amount of aluminum chlorid in the converte-r as near as possible to the desired amount of 10 per cent by weight in the unit. High boiling .point oil may be fed in continuously through line '50. When this is done and retort 54 fired the aluminum chlorid is distilled through line 59 to the condensing chamber, kettle or a still through line 62. If the vapors be sent to a condensing chamber the aluminum chlorid will be taken fromsuch chamber, placed in a mixing kettle and mixed with high point boiling oil and pumped into a still. However, the vapors from the retort 54 may be sent by line 59 to the converter, advantageously near the top thereof by line 61 and into the vapor space. These vapors will contain not only aluminum chlorid, but vapors of higher boiling oil withdrawn with the sludge.

This will allow the aluminum chlorid to sublime directly into the converter. l

.In order to take care of anyhydrochloric acid or other 'chlorin-containing gas formed in the recovery of aluminum chlorid in the retort54, the gases going from the branch A second 25 63 may be` passed over metallic aluminum or other aluminous material.

After the new aluminum chlorid has been charged into the converter through the line 50 equivalent to the amount of aluminum chlorld drawn out with the sludge through line 51, the converter is operated until 115th to 5 gallons of gasoline per pound of aluminum chlorid in the charge has been distilled over. er cent more or less of the sludge from t e converter unit is drawn olf into the second retort- 54 to recover aluminum chlorid and the vapors from the iirst retort are charged or sublimed back into the converter or another converter or still.

This cycle is carried out continuously in drawing oi and passing the recovered aluminum chlorid back into a still with suiicient new aluminum chlorid to take care of the loss.

The sludgeis drawn off before it has done the maximum amount of work in the still so that it is easily handled. The capacity of the gasoline over head is greater and the Baume gravity is higher because the higher boiling oil is acted on by the new or recovered aluminum chlorid and the process is not .allowed to run to a heavy sludge or a coke.

The abovedescription is given by way of example. We do not limit ourselves tothe use-of 10 per cent aluminum chlorid. We have found in operation that 10 per cent .works very well, but we may go even below 5 per cent and we have wo-rked this process very satisfactorily with higher amounts than 10 per cent.

While we have shown four recovery retorts and a single still it is to be understood that a greater or less number of retorts may be used and any desired number of stills; and that these retorts and stills may be connected in any desired way, sequence or phase. For example, one still may be delivering partially exhausted aluminum chlorid .to a given retort and this retort furnishing distilled aluminum chlorid and oil to another oil still, or the volatile products from a given retort may go back to the still whence the aluminum Chlo-rid was withdrawn. e

The temperature required in recovering aluminum chlorid from partially exhausted residues, as contemplated in the present invention, varies with circumstances, and particularly with the age, that is, the degree of exhaustion of the chlorid, but in all cases is much 'lower than that necessary in recovering chlorid from coky or asphalt-ic residues of practically exhausted activity.V

One condition affecting the temperature needed in recovery is the amount and character of the oil accompanying the sludge to the retorts, or supplied with it. Other things being equal, the more there is of this oil and the easier it distills, the lower is the reco-very temperature, since oil` vapors carry aluminum chlorid vapors forward with them. Sometimes a substantial degree of recovery may be had at a'temperature range as low as 350 to 400 F.; and sometimes temperatures as high as l500 or 600 F. are needed. In a general way, it may be said that with residues of proper character, it is not necessary to go as high as cracking and coking temperatures, say 700 or v800 F. But when the recovered vapors of aluminum chlorid and oil are not to be used immediately temperatures higher than 800 F. may be used in the recovery retort.

What We claim is l. The process of converting higher boil- `ing oils linto lower boiling oils which com- .prises distilling the higher boiling oils in and aluminum chlorid, tapping from the lower portion of said body a settled mixture of the higher boiling oil and aluminum chlorid, heating such tapped oil. mixture, and passing the volatile products of such heating to the vapor space above the body of anhydrous aluminum chlorid and higheil boiling oils undergoing conversion.

3. In the conversion of oils by aluminum chlorid, the process which comprises distilling a high boiling oil in the presence of active aluminum chlorid until a distillate of not substantially less than one-tenth gallon and not substantially more than five gallons per pound of aluminum chlorid present is obtained, withdrawing aluminum chlorid in the form resulting from distillation to said extent, recovering from said withdrawn material aluminum chlorid in active form and delivering it to the high boiling oil undergoing distillation.

4. In the conversion of oils lby aluminum chlorid, the process which comprisesl distilling a high boiling oil inthe presence of active aluminum chlorid until gasoline of not substantially less than one-tenth gallon i withdrawing aluminum chlorid in the vform resulting vfrom distillation to said extentI and adding aluminum chlorid and oil to 'I replenish losses by distillation and the Withdrawal of aluminum` chlorid.

VIn testimony whereof We have hereunto signed our names at Port Arthur, Texas, this 25th day of November, 1921.

GEORGE L. PRICHARD. HERBERT HENDERSON.

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