US2266019A - Hydrocarbon conversion and polymerization - Google Patents

Description

Dec. 16, 1941. F. E. FREY 2,266,019

HYDROCARBON CONVERSION AND POLYMERIZATION Filed- Jan. 27, 1937 2 Sheets-Sheet 2 IN V EN TOR.

FREDERICK E. FREY A TTORNEYS.

Patented Dec. 16, 1941 UNITED STATES PATENT OFFICE HYDROCARBO'N CONVERSION AND POLYMERIZATION Frederick E. Frey, Bartlesville, out... asslgnor to Phillips Petroleum Compa y. a co ration of Delaware Application January 27, 1937, Serial No. 122,658

. 11 Claims.

This invention relates to the conversion of low boiling hydrocarbons into higher boiling hydrocarbons, and more particularly to a process wherein a mixture of olefinic and saturated hydrocarbons while under pressure and at a reaclion temperature in agaseous or vaporous state,

is subjected in a reaction chamber to conditions of high turbulence while undergoing reaction to produce in high yield hydrocarbons of higher molecular weight suitablefor motor fuel.

Another object of this invention is to provide, in a simple form of apparatus, means wherein olefins may be thereby dispersed in paraflins as the olefins are consumed by reaction, thereby augmenting the formation of higher parafilns by paraffin-olefin union.

Another object of this invention is to provide a processior the reaction of an olefin-containing hydrocarbon mixture with a mininiumiormation of higher boiling hydrocarbons beyond the ordinary gasoline boiling range.

A further object of this invention is to provide a process whereby gaseous reactions involving olefin-containing hydrocarbon mixtures are carried out adiabatically in a reaction chamber, except as the incoming andefliuent streams will have a sensible heat content.

Still a further object oi. my invention to prov vide a process wherein a parailln-olefin hydrocarbon mixture is subjected in a reaction chamber of enlarged cross-sectional area to reaction higher gaseous parafllns being relatively low,

.such as illustrated in the following table, when the cracking pressure is low.

' TABLE I It has been proposed to subject this material, under an elevated pressure and at a suitable temperature, to reaction in an elongated tube coil, surrounded by a gaseous fluid of a temperature lower than the reaction temperature. Such a reaction is highly exothermic in' nature, and

the surrounding fiuid,oi a lower temperature than the reactants, remove some of the heat produced by the reaction so that the reaction will not overheat the reaction coil and becom uncontrollable.

conditions favorable to the juncture of paraflln and olefin molecules to produce predominantly non-aromatic polymers in particularly high yield, based on olefin consumed.

Still a further object of my invention is to efiect thermal conversion oi a mixture of simple parafilns and olefins into motor fuel in an enlarged reaction chamber in a new manner whereby an increase in yield and in conversion per thermal treatment is realized.

Further objects and advantages will become apparent as the discussion and disclosure proceed.

When heavier petroleum oils are crackecl'in the vapor phase to produce a hydrocarbon tractionboiling in the gasoline range there is produced, in addition to oils heavier than the original material, a mixture of normally gaseous hydrocarbons. This mixture may be treated by absorption or compression to recover hydrocarbons containing five or more carbon atoms 'per molecule, and the residue from such treatment will consist oi normally gaseous components with a high content of olefin hydrocarbons and some hydrogen. Such a gas will contain 50-75 per cent by volume of ethane and lighter material, including some hydrogen, and the total mixture will contain about 50 per centor more by volume or unsaturated hydrocarbons, the content oi the It has also been proposed to heat a normally gaseous hydrocarbon mixture containing little if any hydrogen and with about 25 per cent by volume or more of unsaturated hydrocarbons, and pass it into a thermally insulated enlarged reaction chamber where reactions take place to form higher molecular weight hydrocarbons, such reactions involving the olefinic hydrocarbons present. The composition of such a gaseous mixture is given in Table II.

TABLI II Constituents Volume Per cent OH". 6. 0 CIHA 7. 3 as Guilt: 3211 C l- 4. 1 01H 8. 2

These reactions are exothermic nature, and

the temperature is prevented from rising excessively by controlling the reactions with respect to the chemical and physical properties of the reactants and of the products desired, and with an appropriate degree 01' preheat. Gases produced,

from petroleum oils by familiar-pressure cracking processes are among those suitable for. conversion, as these gases contain lower volume percentages of olefin and higher percentages of the higher gaseous parafdns, such as propane and butane, than gases produced by low pressure vapor phase cracking.

Processes have also been disclosed wherein it is proposed to treat artificially compounded hydrocarbon mixtures of olefin concentrations of per cent or less, operating in such a manner that reactions involving union of parafiins and olefins are predominant, wherein higher molecular weight paraflins formed as the result of such reactions constitute the major products. Such reactions are favored by high pressures and low olefin concentrations, the latter brought about by carefully controlled and proportioned addition of olefins to predominantly parafiinic hydrocarbon streams.

I have disclosed one method of operating these processes in the U. S. Patent 2,002,394, issued to me May 21, 1935, for a'Process for converting hydrocarbons. Here the reactions between the olefins and the parafiins are favored and reactions involving olefins only are minimized by the low olefin concentration at any one point.

One of my copending applications, Serial Number 12,981 filed March 25, 1935, for a Process for converting hydrocarbons, which is now U. S. Patent 2,104,296 discloses reactions between paraffins and olefins, wherein paraffinic material is passed through an endless circulatory cycle,- while maintained at reaction temperature and pressure, and an olefin-containing hydrocarbon mixture is introduced at one part of the cycle, the concentration of olefins at any part of the cycle being small, and a part of the stream, from which products are to be separated, is Withdrawn from another part of the cycle.

In another of my copending applications, namely the application by Frederick'E. Frey and Harold J. I-Iepp, Serial Number 106,482 filed October 19, 1936, for Process for producing hydrocarbons; which is now U. S. Patent 2,209,450 it is proposed to react paraffinsand olefins by introducing small amounts of olefins into a parafiinic stream at a single point, and allowing the reaction to proceed in a continuation of the tube coil or'by introducing the mixture under pressure and at a reaction temperature into an enlarged chamber where reaction proceeds.

In thermal and catalytic processes for converting lower molecular weight hydrocarbons to higher molecular weight hydrocarbons, now known to the art, especially where use is made of reaction chambers for reacting hydrocarbon mixtures of substantial olefin content, there is a strong tendency for olefinic hydrocarbon molecules to react with other olefinic hydrocarbon molecules, thereby forming progressively higher molecular weight molecules. This is especially true when local concentrations of olefinic molecules are high. Such progressive reactions tend to become quite deleterious in nature, and heavier oils are formed which are out of the gasoline boiling range and which tend to producetar and coke easily. If a large reaction chamber is used reactions may not take place uniformly throughout the chamber, resulting in a product ing only olefins arepredominant, the proportion of normally liquid hydrocarbons then formed is low in processes heretofore known to the art. In such a case the greater part of the paraffin hydrocarbons present will be present essentially as inert material, needlessly overtaxing various pieces of equipment used in the process and thus making. operating costs unnecessarily high in consideration of the value of products obtained.

I have found that a normally gaseous hydrocarbon mixture containing both olefins and parafiins can be thermally treated in such a manner that the reaction of olefins with parafiins can be effected to produce high yields of motor fuel, with decreased degradation to heavy tar, in a reaction chamber of large cross-section by injecting the reactants at such a velocity and in such a direction that uniform direct transit through the reaction chamber from inlet to outlet is prevented, but instead a turbulent circulatory motion is maintained within the chamber while the entering reactants are dispersed intimately in large volumes of thepartly reacted hydrocarbons and While a reaction temperature preferably of 700 to 1100 F. is maintained. I have also found that if high pressures are maintained during conversion, namely in excess of 1000 pounds per square inch and preferably of 2000 to 4000 pounds per square inch or more, higher yields of hydrocarbons in the gasoline boiling range are obtained, and the higher the pressure the more efficient is the consumption of paraffin hydrocarbons by direct union with olefins. Indeed with proper equipment pressures of 5,000 to 10,000 pounds per square inch or more may be used.

A novel feature of my invention is the use of a reaction chamber which will serve a somewhat diiferent' purpose from those previously used in the art of hydrocarbon cracking and polymerization. Its general design and construction, and the design, construction and position of the inlet and outlet connections will be such that the reactants within it will be put into and maintained in a high state of turbulent circulation and mixing. In the familiar cracking of petroleum in an enlarged reaction chamber, such circulation of hydrocarbon material within the chamber is undesirable in manyin the chamber will involve the juncture of olefins and parafins to form higher molecular weight parafiins, and progressive reactions which involve only olefin hydrocarbons are limited in extent so that formation of heavy tars and coke is minimized.

Hydrocarbon material suitable for conversion I in my process will contain both parafi'lns and 01efins, both of which enter into reaction. Of the parafiins, propane, butane and pentane are particularly suitable since they readily enter into reaction with unsaturated hydrocarbons. Ethane and methane areless reactive and in many cases it will be desirable to limit the quantity thereof present in the conversion stock. Any of the sim- 2,266,019 ple unsaturates, namely ethylene, propylene,

are not directly very suitable for the process, al-

though the content of the highly desirable ethylene is high, because the amount of parafiins other than methane and ethane is too limited. The gas produced by pressure cracking yields a concentrate containing both suitable paraifins and olefins, usually of suitable composition'but with the paraiflns in marked predominance. A mixture of methane-low concentrates of vapor phase and pressure cracking gases is accordingly highly suitable because it contains olefins rich in ethylene associated with the desired paraflins.

The paraffin content of conversion stock for my process should preferably consistmainly of parafiins higher than ethane accompanied by unsaturates constituting from 10 to 50 per cent by volume, or somewhat more, of the total conversion stock. The conversion stock may also contain unconverted hydrocarbons separated from the eliluents of the process which are usually depleted in olefin. Thus such a predominantly paramnic recycle stream consisting mainly of unreacted propane and butane, may be mingled with a charge stock of higholefln contentto form a very desirable conversion stock.

I use reaction temperatures of 700 to 1100 F., a temperature range wherein olefin hydrocarbons are known to polymerize with themselves under pressure, but wherein paraifin' hydrocarbons decompose only slowly, when given an equal reaction time. Nevertheless, the paraflin molecules are in a more or less activated condition, and are capable of reacting with olefin molecules to produce higher molecular weight hydrocarbons, generally parafflnic in nature.

In the practice of my invention the average reaction time or period of residence of the reactants within the reaction chamber will be dependent on the temperature within the chamber, upon the composition of the conversion stock, and upon the design of the reaction chamber. Th principal and most desired reactions will tend to reduce the specific volume of the hydrocarbon mixture and increaseits parafllnicity, and the extent of these characteristic properties will need to be taken into consideration also. I prefer to operate my process so that at least half of the olefins charged to the process undergo a reaction, and the eflluents of the reaction chamber should not contain more than to per cent by volume of unreactd olefin molecules. To fulfill these conditions the average reaction time should be at least seconds and should' not be more than minutes, and I have found that the best results are generally obtained with a reaction period of 1.5 to 7.5 minutes. Exact temperatures and reaction periods for any particular case may be readily determined by trial.

In the practice of my process the use of pressures above those heretofore employed, in simple fied type of reaction chamber,

r 3 thermal polymerization of olefin-containing hydrocarbon gases in a reaction chamber, decreases formation of heavy hydrocarbons unsuitable for motor fuel, and with increase in conversion pres- 1 sure within my disclosed range, the formation of these undesirable heavy products is increasingly suppressed. This is a contrast to the usual result when the active turbulent circulation and dispersal of reactants is not employed, such procedures usually leading to increased formation of heavy products with increase in pressure, which also is the usual effect of pressure increase when petroleum oils are cracke I prefer to practice my process in such a manner that reaction takes place in the reaction chamber without substantial addition of heat or abstraction of heat from the chamber. Since the reaction is exothermic the reactants may be heated only to such a degree as will sustain reaction in the chamber at the desired temperature levels. Thus the temperature of the hydrocarbons entering the chamber maybe as much as F. or more lower than the temperature of reaction within the chamber, high olefin contents permitting relatively low preheat temperatures. This is of advantage in preventing reaction prior to dispersal in the chamber, since the less desired olefin polymerization tends to set in at lower temperature than the paraffinconsuming reactions in the chamber.

Under the conditions of turbulent circulation and mixing disclosed herein, and treating hydrocarbon gases of the compositions discussed, I have been able to obtain ultimate yields of higher boiling material in the gasoline range of about 1.25 to 2.5 or more times as large by weight as I have at other times obtained under similar temperature and pressure conditions, but using reaction zones such that reactions involving only .olefins took place. Furthermore, the products of my present process are .considerably more parafiinic in, nature. This feature adds greatly to their desirability as motor fuels, as they have very good antidetonating qualities which can be considerably improved with only small additions of tetraethyl lead or other detonation inhibitors, and they are not particularly subject to gum formation and are quite stable during prolonged storage. Y

My invention will be more clearly understood by reference to the accompanying drawings, which form a part of this specification. and wherein,

Fig. 1 is a diagrammatical illustration of one form or arrangement of apparatus for realizing my invention,

Fig. 2 illustrates one type of reaction chamber, 7

r Fig. 3 is a side view of the reaction chamber as illustrated in Fig. 2,

Fig. 4 illustrates in perspective a modified type of reaction chamber,

Fig. 5 is a transverse cross-sectional view of the reaction chamber as illustrated'in Fig. 4, and is taken on line 55 thereof, looking in the direction ofthe arrows, I

Fig. 6 is a side view illustrating another modi- Fig; 7 is a side view, being broken away in part, illustrating still another type of reaction chamber,

Fig. 8 is a side view, being broken away in part,

illustrating a further type of reaction chamber;

9-9 thereof looking in the direction of the arrows.-

Referring now to Fig. 1, one mode of practicing my invention is as follows:

Hydrocarbon material of suitable composition or which may be heated by othermeans. In

passing through the coil l3 the hydrocarbon mixture,,or stream, is rapidly heated to a more or less elevated temperature, usually less than 1100 F., sufiicient to sustain reaction in the reaction chamber to which it passes. It is desirable that this heating take place rapidly, so that no appreciable or extensive reactions will take place in the coil I3.

From coil IS the stream is passed through :on duit l5 directly to a reaction chamber such as will be described hereinafter and which is designated here by the numeral I 6, and which is so constructed that a high degree of turbulent circulation and mixing may be maintained therein, and the stream is introduced into chamber IS in such a manner as to create and maintain this turbulent state, as will also be discussed hereinafter. Effluents from the reaction chamber l 6 are passed through conduit l1 and expansion and control valve l8 to separator 19. Separator I9 will preferably be operated at a pressure of about 200 pounds per square inch or more, but appreciably less than the pressure maintained in reaction chamber I6. Heavier products of the reactions will pass through conduit 20 to separating means 2 I, wherein heavier oils and tar are separated and discharged through conduit 22 and valve 23. A fraction containing the gasoline boiling range hydrocarbons produced is passed out of the process through conduit 26 and valve 25, and may be subjected to further treatment with stabilization of the gasoline.

Eliluents from the chamber IE not passing through conduit 20 will consist of unreacted material and lighter material. These are passed out of the separator I9 by means of conduit 26 to separator 2'l, wherein a separation is made between unreacted material and lighter material. Lighter material is discharged through conduit 29 and valve 28. Unreacted hydrocarbons are discharged from the separator 21 through line 39,

and may be discharged from the system through valve 3!. Any part or portion or all of this material may be passed through conduit 32 and valve 33 and into pipe where it is mixed with the incoming hydrocarbons and subjected to further treatment. v

It is to be understood that the reaction chambers and all modification thereof herein described are constructed to withstand relatively high pressures and temperatures, and therefore suitably constructed and fabricated from metal. With referenceinow to Figs. 2 and 3 wherein are illustrated one form of reaction chamber which may be used in practicing this invention, it is to be noted that Fig. 2 is a plan view of the same, while Fig. 3 is a side view thereof. Such a reaction chamber is of the general configuration of a hollow oblate spheroid, designated by the reference numeral, 40, and having the major axis A evidenced'in Fig. 2, and the minor axis B as evidenced in Fig. 3; The ratio of A to B may conveni'ently be between the limits of 5:1 and 1:1, andispreferably about 2:1. The reaction chamascetic ber id here under consideration may be provided with an inlet conduit 68, through which the efilucuts from the heating coils, such as the ones described in Fig. 1 enter the interior of the reaction chamber; The axis of the inlet conduit M is preferably on a line with the extension of a chord of the largest possible circular cross section of the spheroid constituting the reaction chamber 40. This allows the heated reactants entering chamher All by way of conduit H to enter therein in such a manner as to set up the desired turbulence and circulation within the chamber.

Reaction chamber $8 is provided with an outlet conduit 42, the axis of which is preferably coincident with the minor axis B of the chamber, and on a line with the center of rotation of the spheroidal reaction chamber. The end of the outlet conduit 42 disposed within the reaction chamber 40 may be provided with apertures at the end thereof as shown at 3, and also provided with an aperture at the top thereof as at M.- The end of the outlet conduit 42 may be closed, if desired, and the contents of the chamber will then pass therefrom through the apertures '43 and 44 above described.

Other types of reaction chambers may be used which will also insure the introduction of the eflluents from the heating coils into the chamber in such a manner that the eflluents therein un-- dergo turbulence and circulation. For instance a modified type of reaction chamber is illustrated in Figs. 4 and 5, the body of which comprises a prolate spheroid generally designated by the reference numeral 50, having an inlet conduit 5| and an outlet conduit 52, the inlet conduit being positioned with respect to the chamber in relatively the same manner as the inlet conduit of the reaction chamber 40. The portion of the outlet conduit 52 positioned within the reaction chamber is provided with the apertures 53 and 54 as shown.

Fig. 5 is a transverse cross-sectional view of the chamber illustrated in Fig. 4, and is taken on line 5-5 thereof looking in the direction of the arrows, and shows the inlet and outlet conduits 5i and 52 respectively, and their position with respect to the chamber 5!].

Still another modification of a reaction chamber suitable for use in practicing this invention is illustrated in Fig. 6. Here the reaction chamber generally designated by the reference numeral 5t, comprises a pair of parallelly disposed conduits 6i and 52, which are joined at either end by the curved conduits t3 and 5%. To the ends of either of the curved conduits may be fitted the inlet and outlet conduits. As illustrated the inlet conduit $5 is fitted at or near one end of the conduit 63 and so disposed as to be substantially parallel with conduit 68, while the outlet conduit 66 is fitted at or near another end of the curved conduit 53 and is positioned substantially parallel with respect to conduit 62. The diameter of the reaction chamber 6t, being the same as the diameter of the respective conduits 6|, 62, $3 and 64 is preferably about eight (8) or more times larger than the diameter of the inlet conduit 65, and more preferably. up to twenty (20) or thirty (30) times larger, or

more. g

It should be apparent that such a reaction chamber as the one designated by the reference numeral 60, and illustrated in Fig. 6, will serve to set up turbulence in the eliiuents from the heating coil when the same eflluents are introduced into the reaction chamber by way of the conduits arranged in different positions as is,

desired. If only one inlet is to be used it may be positioned in the manner of the inlet conduit 14 shown in Fig. 7. An outlet conduit is provided at 15.

In Figs. 8 and 9 there is illustrated a still further modification of a reaction chamber, which is based on the modified type illustrated in Fig. '7, but which is provided with several inlet conduits. The reaction chamber is generally designated by zation of concentrated and undispersed oleflns as they emerge from the inlet into the chamber. At high inlet velocities dispersal is more efilcient than at lower ones, although the lower velocities may be adequate for sustaining circulation. Dispersal may be assisted by baflles or equivalent scattering devices upon which the stream impinges, or a Venturi throat or a series of Venturi throats of increasing diameter, the smaller discharging into the larger, surrounding the incoming stream, the use of multiple jets, and other expedients which will be obvious for such use.

This turbulent circulation and mixing within the reaction chamber of my process, designated by the numeral IS in Fig. 1, is different from the turbulence which exists in-the conduit IE the reference numeral 80, and essentially comprises a cylindrical portion 8| provided with the end portions 82 and 83. Inlet conduits 84 and 85 arev provided as illustrated, and are disposed at an angle, but not necessarily the same, with respect to the transverse axis of the cylindrical portion 8| of the reaction chamber 80. It is preferable that the axis of one of the inlet conduits form a plane with the axis of the outlet conduit, and that at least one of the other inlets,'or the other inlet, have an axis which is not in this plane and which does not intersect either of the aforementioned axes. Where a plurality of inlets are used, the combined crosssectional area of each may be such that the linear velocity or the incoming jet of reactants, or eflluents, from each inlet will be the same'as if only one inlet conduit was normally used. That is, the cross-sectional area of any one inlet conduit will be in an inverse relationship to the number of inlet conduits, or in lieu of such an arrangement greater inlet velocities may be used. The use of a plurality of inlet conduits in a reaction chamber of this design will help eliminateof large cross-sectional area the length being preferably less than 5 times the diameter. The injection of reactants into the chamber must take place at a linear velocity sufiiciently high to circulate the contents within the chamber at least 3 and preferably 10 or more times on the average past the point of injection, the more vigorous circulation being required with conversion stocks of high olefin content. For a reaction chamber of given size it is possible by hydrodynamic calculation to determine the inlet velocity required and the extent to which the crosssection of the inlet orifice must be restricted to obtain the desired degree of turbulent circulatory motion. The inlet orifice may be merely a prolongation of the heating coil of suitably restricted cross-sectional area. The dispersal of the incoming reactants into the circulating contents of the chamber should be sufllciently rapid and complete to minimizepremature polymeri immediately prior to its discharge into the chamber. The linear velocity of the hydrocarbon material being heated in the tube coil i3 will generally vary from 20 to 40 feet per second when this heatingsection is designed along conventional lines, and this is in the range of turbulent flow within the tube coil under the conditions which exist. The restricted cross-sectional area of the coil and the linear velocity-oi flow through it permits of local mixing only. Introducing sucha stream into reaction chambers as disclosed insures a difierent effect, namely a rapid and thorough mixing of heated and activated reactants .with other and partially reacted hydrocarbon material which is turbulently circulating within the chamber. This circulating hydrocarbon material is in violent agitation, so that extensive over-reacting of localized portions does not take place, and adequate opportunity is given for olefins to react with parafilns while thinly dispersed in their presence.

While my operations have shown that with chambers designed as those previously discussed,

or in anyvariation of these designswhich would be readily conceived by one skilled in the art, a linear velocity of the incoming mixture oi? 10 or 15 feet per second is enough to set up and maintain some turbulence within the reaction chamber, velocities of 20 to 40 feet per second through the heating coil are generally available and more desirable. Still higher velocities are usually preferable, and to obtain them the heating coil is u and the inlet conduit [5 may be of smaller cross section than is usual in gas conversion heating coils, or the end of the conduit l5, discharging into the reaction chamber, may be of restricted cross section, without prohibitive friction losses, so that the jet of reactants entering the chamber will have a velocity of 50 to 200 feet per second or more, and I may use such velocities in my process. A pressure drop equivalent to the velocity imparted will be experienced at such a constrictlon. Such discussion as given here is understood to pertain to any particular reaction chamber which may be used in this process.

In general, in this process it is desirable to maintain, (1) the reactants and products in circulatory motion in a large portion oi. the reaction zone, (2) eilicient dispel-sal o! olefin-bearing con- As an example of the successful operation or this invention, a hydrocarbon mixture containing 7.8 per cent by weight of ethylene and 92.2 per cent of isobutane was rapidly heated to a temperature of about 915 F. and injected from a small orifice at a velocity of about 40 feet per second into a cylindrical reaction chamber having a length about four times the diameter in such a manner that extensive circulation and turbulent mixing took place. The chamber was insulated so as to be practically without any heat loss, and the temperature of the emuents was about 940 F., the rise in temperature being due to the exothermic reactions taking place. The average period of reaction within the chamber was about 4 minutes, and the pressure was maintained at 4500 pounds per square inch. The eilluents contained 9.0 per cent by weight of gasoline, of the composition shown in Table run A.

The hexane fraction from this run was isolated from the liquid products and found to consist of ethylated isobutane, chiefly 2,2-dimethylbutane. The total gasoline was subjected to routine motor fuel tests. The olefin content was small, and the gasoline was predominantly para-lo, being very low in aromatics content. It had a Reid vapor pressure of only 8.3 pounds per square inch, and an octane number of 85. The addition of one cc. of lead tetraethyl per gallon increased this octane rating about ten units, an increase which is unusually high for a motor fuel with such a high 7 initial octane number, and especially for a motor fuel produced by thermal conversion of an olefincontaining normally gaseous hydrocarbon mix- I ture.

EXAMPLE n As an example of the operation of this inven tion at considerably less pressure, a hydrocarbon .mixture containing 9.8 per cent by weight of EXAMPLEIII In order to bring out more completely the advantages of this invention, a third example is presented for contrast. A hydrocarbon mixture containing 16.5 per 'centby weight of ethylene and 83.5 per cent of lsobutane was rapidly heated to a reaction temperature of 941 F. under a press sure'of 4700 pounds per square inch and allowed to react in an extension of the heating coil for a.

period of 5.1 minutes, wherein no turbulent mix- The eiiluents contained 20.4 percent by heavier liquids were formed, and that a, large amount of unsaturated hydrocarbons are present. The liquids corresponding to octane and higher were rich in aromatics.

TABLE III Gcsolme from normally gaseous hydrocarbons Run number Temperature F.) 940 968 941 Pressure (lb. per sq. in.) 4, 500 2, 500 4, 700 Average reaction time (min utes 3. 2 4. 3 5. 1 Charge composition, weight per cent (per cent by volume):

4 7.8(15) 9. 808.4) 16.5(29. l) ISO-04H") 92. 2(85) 90. 2031. 0) 83. 5(70. 9) CgHl in eiiluent stream l. 6 l. 0 0. 01H; in charge which reacted 6. 2 8. 8 16. Weight per cent gasoline per pass 9. 0 12.8 20. Pounds of product per pound of reacted olefin l. 1. 45 1. Products (weight per cent):

Pentenes 3. 5 5. 7 1 4. 4 6. 2 17. 2 23. 8 2. 9 4. 5 2. 7 46.0 39. 9 l7. 5 2. 7 2. 5 l. 1 9. 3 7. 9 5. 6 2. 9 3. 9 3. 4 ll. 0 8. 0 l7. 2 l3. 7 7. 9 20. 5 1. 8 2. 5 3. 8

' 100. 0 100. 0 100.0 Paraflinlc products octanes and lighter '12. 5 73. 0 64. 1

These three examples have all shown the thermal treatment of a normally gaseous hydrocarbon mixture composed of ethylene and isobutane. The invention is not to be considered to be limited to the use of such a mixture, as these hydrocarbons have no special properties or characteristics which would tend to make them specifically difierent from any of their analogues, nor

should any restriction be made to such a low olefin content. These conditions were chosen only because the product of their interreaction would be easily identified in the eiiiuents, and the results of different experiments would bring out the difierences due to difierent conditions of operation, without being obscured by. results of other variables. Any olefin containing normally gaseous hydrocarbon mixture, containing up to per cent by volume of olefins when treated under conditions most suitable for that particular mixture, will react in an analogous manner.

A consideration of the analyses of the normally liquid products of these three examples brings out three very important and pertinent points.

1. The hexanes produced in run A were 46.0 per cent by weight of the products, in run 13 they were 39.0 per cent, while in run 0 they were only 17.5 per cent. This illustrates forcibly the increased extent of reactions between olefins and parafiins which result from practicing my invention.

2. A consideration of the weight per cent of normally liquid hydrocarbons produced per pass in comparison with the olefin content of the charge stock is very interesting. Although the charge in run C contained 16.4 per cent of olefin which reacted, 2.65 times as much as the charge to run A, only 1.24 pounds of liquid products per pound of olefin resulted in run C while 1.45 pound of liquid products resulted in run A, an increase of 17 per cent in run A.

3. Both runs A and B produced liquid products containing about '73 per cent by weight of satu-' rated hydrocarbons of eight or fewer carbon atoms per molecule, while the products from run 0 contained only about 64 per cent of equivalent material, as well as a considerably larger proportion of heavier liquids and tar. This again is a direct and valuable result of using my invention, which is not demonstrated or hinted at by the workers in the prior art.

As previously discussed herein, I have found that when olefin molecules react with paramn molecules to form higher molecular weight paramns, the reactions are greatly influenced by the total pressure on the system, among other variables. If the total pressure is high, a lower temperature may be used and the parafllnicity of the normally liquid products is considerably increased, and as a concomitant result the ultimate yield of higher molecular weight'material within the motor fuel range is also increased, based on a unit weight of charge stock and any given olefin content. Thus under conditions wherei'ri only 'olefinmolecules react with each other only a limited amount of higher molecular weight material may be formed. But when conditions are therein, introducing the mixture at a linear velocity and in a manner such as to establish and, maintain such circulatory fiow to effect a rapid mixing and dilution of the incoming paraflinic normally liquid hydrocarbons, a major such that paraflin molecules also enter into the reaction, the yield is increased by an amount corresponding more or less to the amount of parafllnic material entering into the reaction. Since, however, the mode of operation also exerts a considerable influence on the products, a more parafllnic material may be produced by practicing my invention atlower pressures than by a less favorable mode of higher pressures, despite the less favorable condition of lower pressure for efllcient participation of parafllns.

In the examples given, run B at 2500 pounds per square inch produced much more parailinic material in the desirable gasoline boiling range than was produced in run 0, although the latter was carried out at a much higher pressure and a somewhat lower temperature. Thus by practicing my invention at 2500 pounds'per square inch pressure, very desirable and beneficial results are produced over conventional once-through processes at equal or even higher pressures.

Considerable discussion has been presented herein concerning the theory of the molecular mechanisms involved in my process. I have observed an unusually high content of paraflln hydrocarbons in the products of my process, and have advanced this discussion only as a possible explanation, and I do not wish to give 'the'ii'npression that I am attempting to claim herein any new and novel theories or mechanisms of reaction, however such theories should not be so construed as to limit the scope of this invention as set forth.

Although preferred methods of operation have been discussed, it is to be understood that my invention. is not limited by such discussions or the examples given, but only by the claims hereto and desire to secure by Letters appended.

What I claim Patent is:

1. In a continuous process for producing normally liquid motor fuel'hydrocarbons from a charge with the circulating more paraflinic reacting mixture, maintaining the mixture in said reaction zone under a pressure in excess of 2000 pounds per square inch and a temperature of 700 to 1100 F. for an average time sufficient to cause the greater part of the olefins to react'thereby producing normally liquid motor fuel hydrocarbons, withdrawing from the reaction zone a reacted hydrocarbon mixture and separating therefrom the last mentioned hydrocarbons.

2. A process for producing predominantly portion of which boil in the motor fuel range, from a normally gaseous hydrocarbon mixture, which comprises substantially continuously pass ing a normally gaseous hydrocarbon mixture containing at least 10% by volume of simple un-= saturated hydrocarbohs and at least 50% by volume of paraifin hydrocarbons having at least three carbon atoms per molecule under a pressure in excess of 2000 pounds per square inch through a heating zone'of restricted cross sectional area and rapidly heating thesaid mixture to a temperature below reaction temperature but suilicient to sustain the reaction temperature in subsequent exothermic reaction, passing the heated mixture through a passageway sufliciently restricted as to cross sectional area to impart thereto a linear velocity in excess of 40 feet per second and introducing the mixture at said velocity into an enlarged reaction chamber in such manner as to maintain therein a high degree of circulation and turbulent mixing, maintaining a reaction temperature between 700 and 1100 F.

within said reaction chamber without substantial addition of heat to said reaction chamber and detaining the reactants in said chamber for an average period of time between 1.5 and 7.5 minutes, said temperature and time being so chosen as to consume the greater part of the simple unsaturated hydrocarbons and produce normally liquid hydrocarbons predominantly parafiinic in structure, substantially continuously -withdrawing a portion of the contents of said normally gaseous hydrocarbon mixture containing not less than 10 per cent by volume of olefinic hydrocarbons predominantly ethylene and 50 per centby volume or more of parafiinic hydrocarbons of three or more carbon atoms per molecule, the steps which comprise heating said hydrocarbon mixture to a reaction-sustaining temperature in a heating zone and introducing the same into a reaction zone which does not include said heating zone as a part thereof, circulating re-.

actants in an endless circulatory flow only within said reaction zone which is so dimensioned as to permit endless circulatory flow and mixing reaction chamber and separating therefrom a fraction comprising hydrocarbons in the motor fuel boiling range.

3. A substantially continuous process for producing normally liquid hydrocarbons predom inantly in the'motor fuel boiling range from lighter hydrocarbons, which comprises substantially'continuously passing a normally gaseous hydrocarbon mixture containing at least 10 per cent by volume of simple unsaturated hydrocarbons and at least 50 per cent by volume of paraffin hydrocarbons having three and four carbon atoms per molecule under a pressure of at least 2000 pounds per square inch to a heating zone, passingv the heated mixture without substantial reduction in pressure to an enlarged reaction zone of such a shape that the contents thereof can be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss of heat through the walls thereof during a period of reaction, introducing said heated mixture at a linear velocity between about 10 and 40 feet per second into said chamber in a direction and manner to establish and maintain said circulation to eiiect a rapid mixing and dilution of the incoming charge with the circulating, more parafilnic reacting aeeaoie and an average reaction time such that at least half of the originally charged simple unsaturated hydrocarbons undergo reaction, substantially continuously withdrawing a portion of the contents of said reaction chamber and separating therefrom a fraction comprising hydrocarbons in the motor fuel boiling range so produced.

4. A substantially continuous process for proe ducing normally liquid hydrocarbons predominantly in they motor fuel boiling range from lighter hydrocarbons, which comprises substantially continuously passing a. hydrocarbon 'mixture comprising such lighter'hydrocarbons and containing at least per cent by volume of simple unsaturated hydrocarbons and at least 50 per cent by volume of paraffin hydrocarbons having three and more carbon atoms per molecule under a pressure of at least 1000 pounds per square inch to a heating zone, passing the heated mixture without substantial reduction in pressure to an enlarged reaction zone of such a shape that the contents thereof can be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss of heat through the walls thereof during a period of reaction, introducing said heated mixing more paramnic reacting mixture, maintain ing a reaction temperature in said zone between about 700 and 1100 F. and an average reaction time such that at least half of the charged low boiling olefin hydrocarbons undergo reaction, substantially continuously withdrawing a portion of the contents of said reaction zone and separating therefrom a fraction comprising normally liquid hydrocarbons in the motor fuel boiling range so produced.

6. A continuous process for producing higher molecular weight hydrocarbons from an olefincontaining normally gaseous hydrocarbon mixture, which comprises rapidly heating in a heating zone a normally gaseous hydrocarbon mixture of essentially paraffinic hydrocarbons of three and four carbon atoms per molecule and to ture at a linear velocity between about 10 and feet per second into said chamber in a direction and manner to establish and maintain said circulation to effect a rapid mixing and dilution of the incoming charge with the circulating, more parafiinic reacting mixture, maintaining a reaction temperature in said chamber between about 700 and 1100" F. and an average reaction time such that at least half of the charged simple unsaturated hydrocarbons undergo reaction, substantially continuously withdrawing a portion of the contents of said reaction chamber and separating therefrom a fraction comprising normally liquid hydrocarbons in the motor fuel boiling range so produced.

5. A substantially continuous process for producing normally liquid hydrocarbons predominantly in the motor fuel boiling range from lighter hydrocarbons, which comprises substan tially continuously passing a hydrocarbon mixture comprising such lighter hydrocarbons and containing at least 10 per cent by volume of low boiling olefin hydrocarbons and at least per cent by volume of paraflin' hydrocarbons havin three and more carbon atoms per molecule and lighter than said products in the motor fuel boiling range under a pressure of at least 1000 pounds per square inch to a heating-zone, heating said mixture in a heating zone to a temperature sumcient to maintain a reaction temperature favoring paraffin-olefln union under the conditions hereinafter set forth, passing the heated mixture without substantial reduction in pressure to an enlarged reaction zone which does not include said heating zone as a part thereof and of such a shape that the contents thereof can be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss of heat through the walls thereof during a period of reaction, circulating reactants in an endless circulatory flow onl within said reaction zone, introducing a stream of said heated mixture into said zone in sucha. direction and manner and at such a linear velocity as to establish and maintain said circulation to eifect a rapid mixing and dilution of said incoming heated mixture with the circulat- 30 per cent by volume of normally gaseous olefins to a reaction-sustaining temperature equal to or less than the reaction temperature maintained in a reaction chamber, introducing the heated mixture under a pressure in excess of 1000pounds per square inch into a reaction zone which does not include said heating zone as a part thereof, circulating reactants in an endless circulatory flow only within said reaction zone which is so dimensioned as to permit endless circulatory flow and mixing therein, introducing said heated mixture in such a manner and at such a velocity that a high degree of circulation and mixing is established and maintained within the zone to effect rapid mixing and dilution of the incoming charge with the circulating more paramnic reacting mixture, maintaining. a reaction temperature within the zone between 700 and 1000 F. for a period or time 'suficient to react a major portion of the oieflns present in the reaction mixture to produce higher boiling hydrocarbons predominantly 'paramnic in structure, continuously withdrawing a reacted hydrocarbon mixture from the reaction mixture, separating the higher molecular weight hydrocarbons produced and discharging them from the process, and also separating essentially parafiinic unreacted hydrocarbons of three and four carbon atoms per unsaturated hydrocarbons and at least 70 per cent of paraflin hydrocarbons having three or more carbon atoms per molecule under a pressure of at least 2000 pounds per square inch to a heating zone, passing the heated mixture without substantial reduction in pressure to an enlarged reaction zone of such a shape that the contents thereof can be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss through the walls thereof during the period of reaction, introducing said heated mixture at a linear velocity between about 10 and 40 feet per second into said chamber in a direction and manner to establish and maintain said circulation to eficct a rapid mixing and dilution of the incoming charge with the circulating, more paraflinic reacting mixture, maintaining a reaction temperature in said chamber between about 700 and 1100" F. and an average reaction time such that at least half of the charged simple unsaturated hydrocarbons undergo reaction, substantiallycontinuously withdrawing a portion of the contents of said reaction chamber and separating therefrom a fraction comprising normally liquid hydrocarbons in themotor fuel boiling range so produced.

8. In a continuous process for reacting low boiling paraffin hydrocarbons of at least three carbon atoms per molecule with olefin hydrocarbons to produce predominantly paraflinic products of higher molecular'weight and predominantly in the motor fuel boiling range, the steps which comprise continuously passing a mixture containing such low boiling hydrocarbons, and comprising between-about 10 and 50 per cent by volume of olefin hydrocarbons and more than 50 per cent by volume of such low boiling paraflin hydrocarbons, at a temperature suflicient to maintain a reaction temperature favoring paraffin-olefin union under conditions hereinafter set forth, to a reaction zone of large cross-sectional area which does not include a heating zone as a part thereof and which is so shaped that the reacting contents thereof may be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss of heat through the walls thereof during a reaction period, circulating reactants in an endless circulatory flow only within said reaction zone maintaining a reaction temperature and pressure within said zone favorable to the union of paraflin and olefin hydrocarbons to form parafiln hydrocarbons of higher molecular weight, introducing said mixture into said zone at a linear velocity and in a direction and manner such that said circulation of the contents of said zone is established and maintained to effect a rapid mixing dilution-of the incoming mixture with the circulating and reacting contents, maintaining said reactants in said zone for an average period of time such that a major portion of the oleflns charged undergo reaction, substantially continuously withdrawing a portion of the contents of said reaction zone, and separating therefrom a fraction comprising normally liquid predominantly paraillnic hydrocarbons in the motor fuel boiling range so produced.

9. A process for producing predominantly parafflnic normally liquid hydrocarbons predominantly in the motor fuel boiling range from lower boiling hydrocarbons, which comprises substantially continuously passing a hydrocarbon mixture containing at least 10% by volume of such lower boiling olefin hydrocarbons and atleast 50% by volume of such lower boiling paraflin hydrocarbons having at least three carbon atoms per molecule under a suitable elevated superatmospheric reaction pressure through a heating zone of restricted cross sectional area and rapidly heating said mixture to a temperature below a subsequent reaction temperature but sumcient to sustain the reaction temperature in subsequent exothermic reaction, passing the heated mixture through a passageway sufficiently restricted as to cross sectional area to impart thereto a linear velocity between about 40 and 200 feet per second and introducing the mixture at such a velocity intoan enlarged reaction chamber in such a manner as to maintain therein a high degree of circulation and turbulent mixing, maintaining a reaction temperature between about 700 and 1100' F. within said reaction chamber without substantial addition of heat to said reaction chamber, and detaining the reactants in said chamber for an average period of time between 1.5 and 7.5 minutes, said temperature and time carbons to produce predominantly paraflinic products of higher molecular weight and predominantly in the motor fuel boiling range, the steps which comprise continuously passing a mixture containing such low boiling hydrocarbons, and comprising a substantial amount of olefin hydrocarbons and more than 50 per cent by volume of the hydrocarbons as such low'boiling paraiiin hydrocarbons, at a temperature sufficient to maintain a reaction temperature favoring paraffin-olefin union under conditions hereinafter set forth, to a reaction zone of large cross sectional area which does not include a heating zone as a part thereof and which is so shaped that the reacting contents thereof may be maintained in a constant circulation therein and so introducing said mixture into said zone at a linear velocity and in a direction and manner such that said circulation of the contents of said zone is established and maintained to effect a rapid mixing and dilution of the incoming mixture with the circulating and reacting contents, maintaining said reactants in said zone for an average periodof time such that a major portion of the olefins charged undergo reaction, substantially continuously withdrawing a portion of the contents of said reaction zone, and separating therefrom a fraction comprising normally liquid predominantly paraiiinic hydrocarbons in the motor fuel boiling range so produced.

11. In a continuous process for reacting low boiling paraflin hydrocarbons of at least three carbon atoms per molecule with olefin hydrocarbons to produce predominantly parafilnic products of higher molecular weight and predominantly in the motor fuel boiling range, the steps which comprise continuously passing a mixture containing such low boiling hydrocarbons, and comprising a substantial amount of olefin hydrocarbons and more than '50 per cent by volume of the hydrocarbons as such low boiling paraiiln hydrocarbons, at a temperature sufflcient to maintain a reaction temperature favoring paramn-olefin union under conditions hereinafter set forth, to a reaction zone of large cross-sectional area which does not include a heating zone as a part thereof and which is so shaped that the reacting contents thereof may be maintained in a constant circulation therein and so insulated that there is substantially no gain or loss of heat through the walls thereof during a reaction period, circulating reactants in an endless circulatory flow only within said reaction zone, maintaining a reaction temperature and pressure within said zone favorable to the union of paramn and olefin hydrocarbons to form paramn hydrocarbons of higher molecular weight, establishing and maintaining a circulation of the contents of said reaction zone only within said reaction zone to effect a rapid mixing and diluting of the incoming mixture with the circulating and reacting contents, maintaining said reactants in said zone for an average period of time such that a major portion oi! the oleflns charged undergo reaction, substantially continuously withdrawing a'portion of the contents of said reaction zone, and separating therefrom a fraction comprising normally liquid predomi- 5 nantiy paraflinic hydrocarbons in the motor fuel boiling range .so produced.

I FREDERICK E. FREY.

CERTIFICATE OF CORRECTION. Patent No. 2,266,019. December 16, min.

FREDERICK E. FREY.

It is hereby certified tl'nt error appearsin the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 11, beginning with the words "Another object" strike out all to and including "union." in line 16, and insert instead the following paragraph It is an object of this invention to provide a process wherein chemical reactions between reactants in the vapor phase may take place in an enlarged reaction chamber while a high gof turbulent circulation and mixing is maintained.

and that the said Letters Patent should be readwith this correction therein that the same may conform to the record of the case in the Patent Office.

Signed ani sealed this 1on1 day of February, A. D. 19LL2.

- Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

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