US3278633A - Process for the production of n-alpha-olefins by the am (alkyl metal) technique - Google Patents

Description

Oct. 11, 1966 O J. SERRATORE ETAL 3,278,633 PROCESS FOR THE PRODUCTION OF n-a-OLEFINS BY THE AM (ALKYL METAL) TECHNIQUE Filed May 15, 1963 Joseph SerrcTore David A. Gudelis I Ronald Vcnder Llnden Inventors By Whelun,Brenner,Choson,Murx 8Wnght United States Patent 3,278,633 PROCESS FOR THE PRODUCTION OF Il-oc-OLEFINS BY THE AM (ALKYL METAL) TECHNIQUE Joseph Serratore, David A. Gudelis, and Ronald Vander Linden, Sarnia, Ontario, Canada, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed May 15, 1963, Ser. No. 280,590

, 5 Claims. (Cl. 260-68315) weight aluminum trialkyls corresponding to the displacing olefins, and (3) separating the displaced higher molecular weight olefins .as product from the lower molecular weight aluminum alkyls formed in the displacement reaction, which lower alkyls are recycled to the process. Still more particularly, this invention relates to the use of two displacement reactions, first employing an olefin having at least 18 carbon atoms and upto about 22 carbon atoms and then employing ethylene or propylene in a manner which avoids or minimizes isomerization in the olefin product as well as loss of C or C alkyl alumihum reactant.

It is-to be noted that olefin employed in the first displacement zone is hereinafter referred to as a C -C displacing olefin for ease of description. It is to be understood, however, that such olefin may also be one having a Poisson distribution about the desired number of caribon atoms, i.e. C -C Thus, the present invention contemplates 2. displacing olefin having a 0 Poisson distribution as well as a displacing olefin having a C Poisson distribution as here later set forth in greater detail.

Some prior art processes have been limited generally to the production of C C olefins, since no practical methods were known for completely separating olefins boiling close to C -C olefins from the C or C alkyl aluminum remaining after the displacement reaction. Thus the C and higher olefins could not be economically distilled overhead from the liquid alkyl aluminum due to the relatively low decomposition temperature of said alkyl aluminum and/or the closely similar boiling ranges of the lower alkyl'aluminum and these higher olefins. Thus, according to the same prior art processes, it was considered necessary to closely regulate the growth conditions so as to obtain a minimum amount of C and higher olefins. Additionally, those higher olefins which were formed required removal by purging, which involved the loss of an important amount of commingled,

valuable alkyl aluminum compounds. Further, in order to keep these alkyl aluminum purge losses to a minimum, the C and higher olefin content of the recycle aluminum alkyl stream was often built up to fairly high levels,

which also deleteriously affected the process due to the cost of circulating large amounts of this material.

In order to produce the desired full range of straight chain olefins it was proposed to employ two displacement reactions, the first employing a C -C olefin and the second employing ethylene. Such double displacement method was found to be highly practical in the separation of olefins in the C -C g range from C -C alkyl aluminum resulting from the first displacement reaction and an improvement over the existing state of the art.

3,278,633 Patented Oct. 11, 1966 However, since separation of the displaced olefinic product from the resulting C -C trialkyl aluminum required a fractionation step, certain inherent disadvantages were found to be present in the double displacement reaction of the prior art. For example use of the fractionation step involved relatively long exposure times .at high reaction temperature and in costly fractionation equipment. Thu-s, because of the thermal sensitivity of the olefins and aluminum trialkyls to isomerization and addition reaction difficulty in obtaining high purity n-alpha-olefins was encountered. Further, in order to accomplish the first displacement, large molar ratios of C -C displacing olefin to aluminum alkyls were required, for example, hexene-l displacement required a 50 to 1 molar ratio in order to effect the desired displacement.

In addition in order to design an economic commercial olefin plant of this type, it is necessary to have available triethyl aluminum or other low alkyl aluminum such as tripropyl aluminum for the growth reaction, at a reasonable cost. It is therefore considered essential that the triethyl or tripropyl aluminum growth reactant be recovered in relatively pure form for recycle to the growth reactor as alkyl growth reactant.

It is an object of this invention, therefore, to provide the art with a novel continuous process for producing olefins over the broad spectrum of C C which have little or no branchiness in the molecule due to isomerization. It is a further object of this invention to provide the art with a process for the manufacture of the aforesaid straight chain olefins having a favorable effect on the critical variables encountered in the thermal displacement reaction, viz: reaction temperature, residence time, and the mole ratio of displacing alpha-olefin to aluminum alkyl. It is also an object of the present invention to provide the art with a simplified process whereby elaborate and costly fractionation equipment may be eliminated entirely or substantially reduced. It is a further object of this invention to provide a process for the preparation of straight chain olefins and concurrently therewith a maximum of triethyl or tripropyl aluminum recovery in a sufficiently pure state for recycle to the growth reactor. These objects and others which will become apparent are eifected by resort to the following described process with specific reference to the appended drawing, schematically illustrating the process. In the exemplary process described, triethyl aluminum is employed as growth reactant whereas this invention also envisions the use of tripropyl aluminum as growth reactant, in which case propylene will be employed in the second displacement zone. In addition, the present invention also contemplates alternate metals in place of the disclosed aluminum. Thus, other metals can replace aluminum providing (1) the volatility of the proposed lower metal alkyls is sufficiently low enough so that vaporization losses during displacement could be minimized, and (2) the lower metal alkyls can readily dissociate to the intermediate alkyl metal hydrides in a manner similar to aluminum alkyls. Representative of such metal alkyls are gallium alkyls, e.g. gallium triethyl, and beryllium alkyls, e.g. beryllium triethyl.

In accordance with the present invention a process for the preparation of olefins comprises reacting a trialkyl aluminum reactant having 2-3 carbon atoms per alkyl group with ethylene under elevated temperatures and ethylene pressures whereby a trialkyl aluminum growth product having from about 2-24+ carbon atoms per alkyl group is obtained, reacting said growth product in a first displacement stage with an olefin having at least 18 carbon atoms and up to about 22 carbon atoms to obtain a first stage alkyl aluminum displacement product which is mixed with olefins corresponding in chain length to the alkyl groups in said alkyl aluminum growth product, separating from said mixture olefins having a vaporization point below said first stage alkyl aluminum displacement product, reacting in a second stage said first stage alkyl aluminum displacement product with a. C -C olefin to obtain a mixture of higher olefins and a second stage alkyl aluminum displacement product and distilling overhead from said mixture said second stage alkyl aluminum displacement product from said higher olefins.

The basic growth reaction involved in the present proc- 'ess can be typified by the following equation:

wherein R, R and R" attached to the aluminum atom represent normal alkyl radicals of the same or different molecular weight.

In the growth reaction, triethyl aluminum or tripropyl aluminum is reacted with ethylene at a temperature between 200500 F. and an ethylene partial pressure of 350 to 7500 p.s.i.g. for 0.5 minute to an hour or more. Ethylene radicals are thereby disposed in between the aluminum to carbon bonds in the triethyl aluminum, enlarging the size of the alkyl radicals on the initial trialkyl aluminum by carbon number multiples of two until a trialkyl aluminum product averaging C -C carbon atoms per alkyl is formed. Starting with triethyl aluminum the growth product will contain even numbered alkyl groups whereas with tripropyl aluminum the growth product will 'contain odd numbered alkyl groups. With regard to the growth product R, R and R" referred to above may in some instances be the same; for example, tributyl aluminum, trihexyl aluminum, tripentyl aluminum, trioctyl aluminum, trinonyl aluminum, triododecyl aluminum, tri tetradecyl aluminum, trihexadecyl aluminum, trieicosyl aluminum, tridocosyl aluminum, etc. However, in most instances the alkyl groups of the trialkyl aluminum growth product will be different. As examples, the growth product may contain a trialkyl aluminum compound such as ethylhexyloctyl aluminum, dibutyloctyl aluminum, octyldodecylhexadecyl aluminum, as well as mixed odd numbered trialkyl aluminum compounds when tripropyl aluminum is employed. Occasionally, alkyl aluminum hydrides occur during growth. Insofar as the growth product is concerned, the lowest boiling trialkyl aluminum is triethyl aluminum which boils close to normal C alpha-olefin under pressures normally employed. Tripropyl aluminum boils close to the C olefin and tri butyl aluminum within the range of C C olefins.

In the drawing, growth reaction zone 1 may be any simple reactor capable of withstanding the necessary pressures and temperatures noted previously. Preferably, however, this reactor will comprise a tubular serpentine-like coil of from 50 to 300 feet in overall length. Since the growth reaction is exothermic and it is necessary to remove heat, heat exchange means must be employed in order to control temperature. While many heat exchange techniques are available it is preferred to use a tube within a tube. The internal tube of, for example, a diameter of /2"10, preferably under 6", comprises the reactor 'wherein triethyl is reacted with ethylene. The outer tube which completely encases the inner tube but which otherwise is not connected thereto will contain the circulating coolant. The outer tube should, of course, have an internal diameter substantially greater than the outside wall of the internal tube to increase heat exchange efficiencies. Alternatively, the tubes may be immersed in a cooling medium.

Ethylene, preferably in a relatively pure state, is introduced into the reaction zone via line 10 with makeup triethyl aluminum via line 12. Triethyl aluminum in line 11 is recycled from a later stage in the process and line 12 is provided to permit adding small amounts of triethyl aluminum make-up. 'If desired there may be provided multipoint injection of the ethylene and/ or triethyl aluminum; however, this is not considered necessary. After the growth reaction is completed within the specified time the growth reaction product containing some unreacted triethyl aluminum and ethylene as Well as trialkyl aluminum containing alkyl groups of from 2 to about 26 carbon atoms is removed via line 13 and passed through to displacement reactor 3 wherein the first displacement is eifected. Preferably ethylene is flashed off prior to the first displacement step by conventional means in flash chamber 2 and recycled to the growth reaction stage via line 14 as ethylene feed.

Prior to the first displacement reactor 3, C -C displacing olefin is introduced via line 15 into the growth reaction product stream 13. The C -C displacing olefin is employed in a mole ratio of from about 3:1 to 30:1 mole of displacing olefin per mole of aluminum alkyl growth product and preferably from 5:1 to 7:1. The first displacement reaction in displacement reactor 3 is carried out at a temperature in the order of from 200 to 350 C., preferably 250- to 300 C., pressures of from 0.1 mm. to 2 atmospheres, preferably 5 to 20 mm. of Hg and for a residence time of from 0.1 second to 2 hours preferably 1 to 40 seconds, thereby generating olefins corresponding to the alkyl groups in the alkyl aluminum growth product and C -C alkyl aluminum compounds.

As the displacing olefin for the first displacement there should be employed any olefin having from at least 18 carbon atoms up to about 22 carbon atoms. Thus, suitable displacing olefins include octadecene-l, nondecene-l, eicosene-l, heneicosene-l and docosene-l. As hereinbefore mentioned, the present invention also envisions use of an olefin having a Poisson distribution that is an olefin having, for example, from a C Poisson distribution to a C Poisson distribution. Thus, it is Within the scope of the present invention to employ the C olefins obtained by the displacement reaction practiced herein. In practice therefore, the displacing olefin resulting from a C average growth alkyl would be a C olefin product with a Poisson distribution in mole percent as follows.

Olefin Mole percent C 4.13 C 2.25 C 1.10 (3 1 08 In accordance with the instant invention, displacement in displacement reactor 3 with C C alpha-olefins yields displaced products which are easily separated in a single short residence time flash operation, thereby minimizing isomerization and side reaction. As heretofore noted in prior art displacement reaction, in order to maintain high conversion in the displacement reaction, a high molar ratio of C -C displacing olefins to aluminum trialkyls is required. However, with the use of O -C displacing olefins, lower molar ratios of olefin to aluminum trialkyls can be utilized to apparent great advantage. This is attributed to the fact that the displaced Cz-Ggo alpha olefins are continuously separated from the resulting aluminum trialkyl product and are continuously removed from the displacement reactor, via line 16, by means of a gas stream or by a reduction in operating pressure. Hence the displacement reaction can approach a complete conversion since the C C displacing olefins are substantially all in the liquid phase while successful use of C C displacing olefins depend on solubility.

Thus, the thermal displacement reaction of the instant invention employs a displacing n-alpha-olefin with a high boiling point in order that the displaced alpha-olefins can be vaporized and removed from the reactor while the high-boiling displacing n-alpha-olefin remains in the liquid phase in the reactor. Such practice permits the use of lower mole ratios of displacing alpha olefin to growth aluminum trialkyl in comparison to the C -C olefin displacement of the art, since the displaced olefin will vaporize andthe undistilled displacing alpha-olefin thereby increases in concentration in the liquid phase, which adds rapidly to the aluminum dialkyl hydride intermediate initially formed in the liquid phase. For example, if docosene-l is employed in the displacing alphaolefin since its boiling point (224 C. at mm. Hg) is sufficiently high to allow it to remain in the liquid phase at the displacement temperature utilized (e.g. 310-315 C.), the following initial-sequence occurs:

(a) The spontaneous splitting of alpha-olefin from the aluminum trialkyl (b) The addition of docosene-l to the aluminum hydride bond The reaction continues until all three alkyl groups R are displaced by docosene-l. As soon as the olefin is formed, it is vaporized and carried away thus shifting the reaction to the right and aiding the displacement reaction.

The displacement reactor 3 utilized in the instant invention can be a tubular reactor, a mixed film evaporator or molecular still, a short residence time fractionator or any other reactor designed so that volatilized alpha-olefins can be removed rapidly, e.g. by using a carrier gas. Suitable for the reactor is a vacuum jacketed fractionation tower packed, if desired, with glass helices and equipped with a reboiler and preheater. The foregoing examples are deemed illustrative and not limiting on the scope of the instant invention. Optimization experiments can be run by one skilled in the art in order to determine the equipment most adaptable to the invention under the particular circumstances encountered.

Referring again to the example and the drawing, the docosene-l displaced stream will contain principally tridocosyl aluminum and C normal olefins. Preferably this tridocosyl aluminum containing stream is passed to a cooler which can be maintained at pressures of about 0.1 mm. or less to 10 atmospheres or more and temperatures of about 40 to 150 C. The tridocosyl aluminum-olefin containing stream is then passed via line 17 onto the sec ond displacement reactor 4. The mixed tridocosyl aluminum-olefin stream is passed through line 17 with fresh ethylene from line 18 into displacement reactor 4, as well as recycle ethylene from line 19. In displacement reactor 4 wherein ethylene will be displacing the docos'yl groups of the tridocosyl aluminum, slightly higher pressures may be employed, e.g. /2 to 20 atmospheres and essentially the same temperature and residence time may be utilized as in the prior displacement reaction. Thus, in a second stage displacement zone the alkyl groups of the first stage alkyl aluminum displacement product are displaced by an olefin having 2 or 3 carbon atoms, i.e. ethylene or propylene and preferably 2 carbon atoms, i.e. ethylene. There is then obtained a second stage alkyl aluminum displacement product which can be separated from the remaining olefins and recycled as described hereinafter. In this specific example the product from the second displacement reaction which is removed via line 20 will contain ethylene, docosene-l, triethyl aluminum and C olefins. The ethylene may be flashed overhead via a conventional flash drum 5 and after separation ethylene may be recycled via line 19 back to the second displacement reaction zone. The remaining triethyl aluminum and C olefin are passed via line 21 to the triethyl aluminum fractionator or evaporator tower 6 wherein triethyl aluminum is taken overhead via line 11 and recycled to the growth reaction zone via line 11. Normal alpha olefins having little or no branchiness are recovered via line 22. The temperatures within fractionator tower 6 must be maintained sufficiently low to avoid a back displacement, i.e. displacement of the ethyl radicals in the triethyl aluminum by the higher molecular Weight olefins, and also isomerization of the alpha normal olefins. Preferably, the temperature within the splitter tower should not exceed 225-275 F. Maximum pressures, of course, should be adjusted to coincide with the maximum temperatures desired in the tower, e.g. 0.5 to 50 mm. Hg, preferably 1-10 mm. Hg.

In order to facilitate a clear understanding of the invention, the initial displacement step of the process of this invention is illustrated by the following preferred embodiments described in detail.

EXAMPLE I In this example, as well as in the following Examples 11 to V a growth alkyl of a C average chain length was utilized. A comparative composition analysis of the growth alkyl was determined and is summarized in the following Table I.

Table 1 Components, weight percent Analysis 1 Ethane n-Butane 3. 00 n-l-Iexane 6. 09 Hexene-l. 0. 22 Unknown 0. 05 n-Octane 9. 40 10. G8 Ootene-l 0. 24 0. 71 Unknown.. 0. 04. n-Decane 12. 41 12. 8 Decene-L 0. 75 0. 78 Unknown 0. 1O n-Dodecane. 14. 25 13. 93 Dodeeene-l 2. 24 1. 57 Unknown 0. 14

Doeosene-l 0. 14 0. 43 n-Tetraeosane. 1 09 1. 21 Tetracosene-l. 0. 21 n-Hexac0sane 0. 71

1 Sample hydrolyzed in cold methanol and analyzed by gas ehromatog rIaItphy using a 15 Reoplex column, F and M Temperature Programmed Docosene-l (boiling point range of 687-705 F.) was employed on the displacing high molecular weight alpha olefin. The initial displacement was carried out in an Asco 50-2 rota-film molecular still primarily because of the short residence time obtainable by this equip ment. The mole ratio of docosene-l to aluminum trialkyl was 4.5/1, the reactor temperature was 316 C. and the pressure was atmospheric (positive flow of N The aluminum trialkyl growth feed was fed through the still at these conditions and the bottoms obtained was recycled through the still at the same conditions. No apparent degradation of the bottoms product was observed and this apparently is attributable to the docosene-l acting as a liquid carrier for the aluminum trialkyl.

The over-all conversion after both cycles was 77% based on C olefin consumption to aluminum alkyl. The mole percent conversion for each aluminum alkyl to pro- Q 7 ca duce the alpha olefin is shown in the following tabula- Table IV tion:

Table II Mole Percent Conversion of AIR to a-Olefins Mole percent Conversion of AlRa to n-alpha-olefin Run Number 1 2 3 4 Components 1st Cycle 2d Cycle Average Temp., 0. 145 168 182 195 Aluminum Alkyls:

A1(C8H17)3 -100 -100 -100 A1 (041103 90.0 AMOwHmS 63.2 97.8 -100 -100 .A1(O6 l3)3--- 61.0 87.8 A](C12['I25)3-- 56.8 93.5 -100 95.4 A a i1)3-- 39. 3 75.8 AMOHHM" 36.8 57. 0 68.7 72. 4 A1 (01011205-- 40. 8 72. 4 .A.1(C1BII33)3- 33. 2 17. 4 27. 1 42. 3 'Al (o 2H25)3 41. 3 69. 8 Al(C1 Ha1)3 10. 0 25. 5 A1 (014mm- 37. 0 60. 5 Al (C1tH33)3- 22. 1 50. 5 Al (Ci H 1);- 16. 6 20.0 15 1 At residence tune of about two hours.

The highest over-all conversion was obtained from Run 4 From this run, it is apparent that conversions can be obin which a conversion of 76.1% of Al(C1 H37)3 and lighttained reaching percent conversions of over 90 percent er alkyl to their corresponding n-a-olcfin was found. In with optimum conditions. The total aluminum loss was all the batch experiments, the solution of alkyl and Ole 2.2 Wt. P r n i the unt of lighter aluminum fins remained clear and amber in colour during the comalkyls vaporized and removed overhead along with the plete run. This suggests that the aluminum alkyls were displaced alpha olefins. remarkably thermally stable to decomposition at these EXAMPLE H conditions since no visible precipitation of aluminum metal was noted. Additional runs employing docosene-l (herein a C EXAMPLE IV 0 C alpha olefin) were made. The 1n1t1al displacement was made in an Asco 50-2 rota-film. The feed com In another displacement experiment octadecene-l positions, feed rates, temperatures and test periods em- (b ili point range 596 5( 6 was used as the ployed are as set forth belowplacing high molecular weight a-olefin. The run was carried out in a continuous vacuum fractionator where Run No. 2 the mole ratio of C olefin to AlR was 2.6/1, the reactor Condltwns Run 1 temperature was 177 C., the pressure was 5 mm. of Hg 1st Pass 2d Pass and the average residence time calculated was about thirty minutes. Under these conditions, an over-all con- Feed, wt. percent: 1 version of 58% was obtained based on C olefin con- 3 55 33 3 55; E Sumption to aluminum alkyl. The mole percent con- Total charge, g 624.4 863.3 355.8 version of each aluminum alkyl to produce n-alpha-olefin gf g fi f Mm 316 mm 1 is summarized in the following tabulation: Feed Rate, cc./m 7.0 6.0 6.06 Test Period, min 120 18 74 Mole Ratio of 0 0-024 a-olefin to 5. 0/1 6.1/1 3. 0/1 40 A1123. Mole Percent Conver- Components sion of AlR to n-alpha-olefin 1 Bottom from 1st cycle.

The experimental data are outlined in Table III. AMQHQ), 7&4 p .Al(C H 81.5 Table Ill auogrriiii 81.0 Al(C10H 79. 2 Al(Ci2H2s)3 68. 2 Mole percent Conversion of AlR to n-alpha-olefm omponen S Run No. 2 EXAMPLE v Run N0. 1

1 tP SS 2d Pass An additional experiment was earned out using octa- S a decene-l displacement with the use of a continuous 1 H 94 4 95 6 99 4 vacuum fractionator and is summarized in the following 2 tabulation. A 2.5/1 mole ratio of octadecene-l to alu- Al 281252555- $2 g g 3-? minum trialkyl was used and 70% of the displacing olefin Al (CiZHZZfiL--- 52:6 66:1 65:4 was converted to aluminum trioctadecyl. Infrared ana- A1 (018E393 lysis indicate the displaced n-tx-olefins to be essentially pure. The best results taken from Run No. 2, second pass, 60 show that over 95% conversion of alkyls up to and 1ncluding Al(C H can be attained. The over-all con- Mole Percent Con- C t fAlR version of AlR up to Al(C H 1n Run No. 2, second Omponen s figif f g pass, upon calculation is 87.7%.

Al Bu "8.4 EXAMPLE In mani {30,4 A1(OaH17)a 79.2 Batch type experiments were carried out in a stirred (010E293 A1(C12 25)a 58. 1 reactor 1n order to determine the effect of temperature A1(C iH 9)3 23.0 exposure time on docosene-l displacement products. Preliminary data for low temperature doc-osene-l displacement of growth alkyls are outlined in Table IV. The EXAMPLE VI reactor temperatures for the Runs 1 to 4 ranged from 140 to 200 C., respectively. The following is a sum- The following example represents a comparison of the marized tabulation comparing the mole percent converdouble displacement with docosene-l and ethylene a d sion of each aluminum alkyl for each run: hexene and ethylene used in conjunction with a C average chain growth alkyl used as feed. In both instances the ethylene displacement was substantially identical. In accordance with the prior art practice one flash. and two fractionation steps were added to the prior art process, thus, illustrating the simplicity of the process of the present invention. 'The results are summarized as follows:

EXAMPLE VII Additional runs were made in order to compare C olefin displacement with C olefin displacement. The following is a tabulation comparing the mole per cent conversion of each aluminum alkyl between docosene-l displacement and hexene-l displacement.

Percent Conversion of AlRa to n-a-Olefins Run No 1 2 3 4 Temp" C 300 300 238 285 Pressure 1 20 2 50 2 50 Olefin/AlRa Mole Ba 4. 92 5. 87 54.1 52. 6 Residence Time, Sec -20 -20 0.42 0.37 Over-all Conversion, Percent.-. 74. 86. 3 74. 0 85.9 Components:

A1(C3H|7)3 93. 7 95. 2 85. 9 90. 7 Al(C|oH21)3 88.3 91. 4 88.0 90.1 Al(C12H2s)a.. 78. 6 85. 6 78. 1 88. 3 Al(CnHza a- 71. 4 79. 71. 4 85. 7 A1(CiuHsa)s 47. 7 75. 6 56. 8 77. 5 A1(C13H37)3 45. 2 64. 4 48. 5 71. 6

l Mm. Hg. 2 P.s.i.g.

When comparing docosene-l and hexene-l displacement conversions, it should be noted that the C olefin displacing olefin yielded higher conversions for aluminum tridecyl and lighter alkyls.

From the foregoing data, it is obvious that the advantages of the present invention comprise at least:

(1) Lower recycle rates of C -C displacing olefin. (2) Aluminum triethyl separation simplified. (3) Elimination of fractionating equipment.

What is claimed is:

1. A process for the preparation of olefins which comprises reacting a trialkyl aluminum reactant having 2-3 carbon atoms per alkyl group with ethylene under elevated temperatures and ethylene pressures whereby a trialkyl aluminum growth product having from about 2-2 4+ carbon atoms per alkyl group is obtained, reacting said growth product in a first displacement stage with displacing olefins having at least 18 atoms and up to about 22 carbon atoms at temperatures of about ZOO-350 C., pressures of about 0.1 mm. to 2 atmospheres and for periods of up to two hours, simultaneously and continuously removing the lower molecular weightolefins which are displaced by said displacing olefins and forming a first stage alkyl aluminum displacement product, reacting in a second stage said first stage alkyl aluminum displacement product with a C -C olefin to obtain a mixture of first stage displacing olefins and a second stage alkyl aluminum displacement product and distilling overhead from said mixture said second stage alkyl aluminum displacement product.

2. A process for the preparation of olefins which comprises reacting triethyl aluminum with ethylene under elevated temperatures and ethylene pressures whereby an alkyl aluminum growth product having from about 224+ carbon atoms per alkyl group is obtained, reacting said growth product in a first displacement stage with displacing olefins having a Poisson distribution of from 18+ to 22+ carbon atoms at temperatures of about 200- 350 C., pressures of about 0.1 mm. to 2 atmospheres and for periods of up to two hours, simultaneously and continuously removing the lower molecular weight olefins which are displaced by said displacing olefins and forming a first stage alkyl aluminum displacement product, reacting in a second displacement stage said first stage alkyl aluminum displacement product with ethylene to produce a mixture of higher boiling first stage displacing olefins and triethyl aluminum, separating said triethyl aluminum obtained in said second stage displacement reaction from the higher boiling olefins admixed therewith and employing said separated triethyl aluminum as initial growth reactant.

3. A process for the preparation of olefins which comprises reacting triethyl aluminum with ethylene under elevated temperatures and pressures whereby a higher molecular weight trialkyl aluminum growth product is obtained, reacting said higher molecular weight trialkyl aluminum growth product with docosene-l at temperatures of about ZOO-350 C., pressures of about 0.1 mm. to 2 atmospheres and for periods of up to two hours to form a mixture of docosyl aluminum and olefins corresponding to the alkyl groups in said higher molecular weight trialkyl aluminum growth products, simultaneously and continuously separating from said displacement reaction product mixture olefins boiling below the boiling point of tridocosyl aluminum, reacting the remaining tridocosyl aluminum and olefins boiling within the range of, and higher than the boiling point of tributyl aluminum with ethylene to form triethyl aluminum and olefins boiling substantially higher than triethyl aluminum, separating said triethyl aluminum from said higher olefins and reacting said separated triethyl aluminum with additional ethylene.

4. A process in accordance with claim 3 wherein said growth reaction is carried out at a temperature of 200- 500 F. and a pressure of '25500 atmospheres for -a period of 0.5 minute to five hours.

5. In a process for producing olefins wherein triethyl aluminum is reacted with ethylene to form a trialkyl aluminum growth product and the alkyl groups of said trialkyl aluminum growth product are displaced therefrom by reaction with displacing higher olefins, the improvement which comprises reacting said trialkyl aluminum growth product with docosene-l in a first displacement reaction stage at temperatures of about 200350 C., pressures of about 0.1 mm. to 2 atmospheres and for periods of up to two hours to form a mixture of tridocosyl aluminum and olefins corresponding to the alkyl groups in the trialkyl aluminum growth products, simultaneously and continuously separating C and lighter olefins from the tridocosyl aluminum formed in said first displacement reaction and higher olefins, subsequently reacting the mixed tridocosyl aluminum and C and higher olefins with ethylene to form triethyl aluminum admixed with C and higher olefins and separating said C and 3,278,633 11 12 higher olefins from the resultant triethyl aluminum by OTHER REFERENCES distilhng said triethyl alurnlnum over Polymerization and Polycondensation Processes, Ad-

vances in Chemistry Series 34, A.C.S., Washington, DC.

References Cited by the Examiner 1962 pages 52 UNITED STATES PATENTS 2,863,896 12/1958 Johnson 260683.15 DELBERT'E'GANTZPmmyEmmme" 2,889,385 6/1959 Catterall et a1. 260683.15 R. H. SHUBERT, Assistant Examiner.

Claims (1)

1. A PROCESS FOR THE PREPARATION OF OLEFINS WHICH COMPRISES REACTING A TRIALKYL ALUMINUM REACTANTS HAVING 2-3 CARBON ATOMS PER ALKYL GROUP WITH ETHYLENE UNDER ELEVATED TEMPERATURES AND ETHYLENE PRESSURES WHEREBY A TRIALKL ALUMINUM GROWTH PRODUCT HAVING FROM ABOUT 2-24+CARBONS ATOMS PER ALKYL GROUP IS OBTAINED, REACTING SAID GROWTH PRODUCT IN A FIRST DISPLACEMENT STAGE WITH DISPLACING OLEFINS HAVING AT LEAST 18 ATOMS AND UP TO ABOUT 22 CARBON ATOMS AT TEMPERATURES OF ABOUT 200-350*C., PRESSURES OF ABOUT 0.1MM. TO 2 ATMOSPHERES AND FOR PERIODS OF UP 5O TWO HOURS, SIMULTANEOUSLY AND CONTINUOULSY REMOVING THE LOWER MOLECULAR WEIGHT OLEFINS WHICH ARE DISPLACED BY SAID DISPLACING OLEFINS AND FORMING A FIRST STAGE ALKYL ALUMINUM DISPLACEMENT PRODUCT, REACTING IN A SECOND STAGE SAID FIRST STAGE ALKYL ALUMINUM DISPLACEMENT STAGE PRODUCT WITH A C2-C3 OLEFIN TO OBTAIN A MIXTURE OF FIRST STAGE DISPLACING OLEFINS AND A SECOND STAGE ALKYL ALUMINUM DISPLACEMENT PRODUCT AND DISTILLING OVERHEAD FROM SAID MIXTURE SAID SECOND STAGE ALKYL ALUMINUM DISPLACEMENT PRODUCT.

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