US3458594A - Growth product olefins process - Google Patents

Description

`luly 29, 1969 L. D. BOYER GROWTH PRODUCT OLEFINS PROCESS 2 Sheets-Shee t 1 Filed April 14. 1965 INVENTOR YA/00N D. BOYER ATTORNEY July 29, 1969 L. n. BOYER GROWTH PRODUCT OLEFINS PROCESS 2 Sheets-Sheet 2 Filed April 14. 196s CARBON NO. Fly. Z

ZTJO ab. F

CARBON NO. F1' Lg. 3

CARBON NO. Fllg. 4

IN V EN TOR.

LYNDON D4 BOYER A TTORNE Y United States Patent O 3,458,594 GROWTH PRODUCT OLEFINS PROCESS Lyndon D. Boyer, Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Filed Apr. 14, 1965, Ser. No. 448,106 Int. Cl. C07c 3/10 U.S. Cl. Zell-683.15 10 Claims ABSTRACT OF THE DISCLOSURE A process is disclosed for controlling the molecular size of alkyl groups on aluminum trialkyls which comprises subjecting aluminum triethyl to growth followed by ethylene displacement, olefins are separated from the aluminum triethyl formed in the displacement zone, and the separated aluminum triethyl passed to a reverse displacement. The olens from the first displacement zone are separated into a light olefin fraction and a heavy olefin fraction, and the light olefins used in the said reverse displacement zone. These resulting aluminum trialkyls are passed back to the growth reaction zone. By the particular sequence of steps, the alkyl carbon number can be controlled, and in recovering olefins no net make of aluminum triethyl is involved.

This invention relates to improvement in chain length distribution of olefins and/or alcohols as obtained from growth of metal alkyls and particularly as obtained from growth of aluminum alkyls.

It is well-known in the art that certain metal alkyls can be grown with low molecular weight olefins to produce metal alkyls wherein the alkyl groups are substantially longer chained than were the original alkyl groups.

Although the art has suggested several metals, including aluminum, indium, beryllium and lithium, only the aluminum alkyls have been successfully commercialized. The length of the original alkyl groups can vary over a wide range and still be grown to greater lengths. The low molecular weight olefin, according to the art, can be from 2 to 4 carbon atoms; however, ethylene has been the growth olefin utilized in commercial practice since the other olens tend to dimerize and/or cause branching.

The growth reaction involves the interaction of a low molecular weight mono-olefin, particularly preferred, ethylene with a low molecular weight alkyl aluminum, particularly preferred, trialkyl aluminum. By virtue of the reaction the mono-olefin adds to the alkyl radicals of the aluminum ycompound in multiples to produce relatively higher molecular weight aluminum compounds. The growth product can be used as a starting material for the production of other useful materials such as, for example, relatively high molecular weight alpha-oleiins and alcohols. One objection to the process is that the alkyl groups give a random distribution resulting from random growth of aluminum alkyls. Thus, only a portion of the growth product is of the moleular range desired.

Various schemes have been proposed to alter this random distribution. A number of these involve total displacement of olens from growth product, fractionation of the olefins, and return of the olefins to the growth step for more ethylene additions. As previously stated, the light olefins, other than ethylene, cannot be returned directly to the growth reactor since dimerization and/or branching results. Therefore, many of these processes involve the preparation of aluminum dialyky hydride compounds to which the light olefins are attached to be recycled to the growth reaction. Unfortunately, the use of aluminum dialkyl hydrides to reuse light olefins usually results in a net make of aluminum or alkyl aluminum compounds ICC somewhere in the process. The magnitude of the net aluminum alkyls produced is so great that they cannot be sold or utilized.

It is, therefore, an object of this invention to provide an improved method of altering the random distribution of growth product olefins or alcohols.

It is another object of this invention to completely eliminate the production of light olefins or alcohols.

It is another object of this invention to provide a method for obtaining only high molecular weight material without a net make of aluminum alkyl compounds.

Still other objects and advantages of this invention will be obvious from this specification and the claims.

Broadly, the invention comprises growing low molecular weight metal alkyls with ethylene, displacing the growth product with light weight olefins forming metal trialkyl and olefins, separating the oleiins from the metal trialkyl, separating the olefins from the prior step into light olefins and desired olefins, recovering the desired olefins, passing the metal trialkyl along with the light olens to reverse displacement wherein a portion of the metal trialkyl is reacted with the light olefins forming metal alkyls and producing said light olefin, separating the product from the prior step into metal alkyls and olefins, passing the metal alkyls back to the growth reactor, separating the displacing light olefin and other light olens, passing the displacing light olefin to the original displacement step or the growth step (however, in case of olefns other than ethylene, then they should be passed to displacement step only) and returning the other light olefins to the reverse displacement step. The preferred light olen is ethylene; however, propylene, isopropylene, butene-l and the like can be used in this zone. The particular light olefin chosen will depend upon product desired.

As has been indicated, aluminum alkyl has been the metal alkyl which has been of major commercial significance and, therefore, the description will be related to such aluminum compounds.

Further description of the process will be described with reference to the figures of which:

FIGURE 1 is a schematic diagram of the process 0f the invention;

FIGURE 2 is a plot of weight percent olefins of given carbon atoms under normal operation of the process;

FIGURE 3 is a similar plot where high recycle is employed; and

FIGURE 4 is a similar plot where low recycle is employed.

Before discussing the figures, it is pointed out that the figures represent one method of accomplishing the purpose of the invention.

The description given is of a continuous process. It is well-known in the art that both batch and continuous processes are equally applicable to all of the reactions and distillation steps shown. In general, the chemistry involved is well-known to the art, and the ranges of conditions indicated are those most generally used. It is within the skill of the art to vary these conditions depending upon the particular range of carbon atom alkyl groups desired.

Referring now to the drawings, and particularly FIG- URE 1, ethylene is passed to growth reactor 2 via conduit 1. Any triethyl make-up required is passed to said growth reactor via conduit 3 wherein the triethyl aluminum along with other low molecular weight aluminum trialkyls supplied via conduit 4 is grown to higher molecular weight aluminum trialkyls. The product from the growth reactor 2 passes via conduit 5 to displacement zone 6 wherein the alkyl groups on the aluminum alkyls are displaced with ethylene supplied via conduit 7 to produce aluminum triethyl and olefins having a distribution produced by random growth. The effluent from zone 6 passes to reactor 8 via conduit 9 where the alumi- 3 num triethyl is reacted with a mono complex of a low Vmolecular weight alkyl ammonium chloride, preferably tetramethyl ammonium chloride, to form the dicomplex. The reactor 8 is equipped with a stirrer 10 driven by motor 11. After the 2:1 or dicomplex is formed, it is passed to settling zone 12 via conduit 13 where the heavier complex settles, and the lighter hydrocarbons rise. The 2:1 complex passes via conduit 14 to column 15 where it is broken down into the 1:1 complex and aluminum triethyl. The mono or 1:1 complex is passed via conduit 16 back to reactor 8 for complexing additional aluminum triethyl and the aluminum triethyl from column 15 passes overhead via conduit 17 to reverse displacement zone 18. This separation of olens from aluminum triethyl is preferred; however, other separation methods, such as extraction, can be employed. In the meantime, the olens pass to wash zone 19 via conduit 20 where they are contacted countercurrently with water supplied via conduit 21. The water washes away any complex or displacement catalyst and is passed to waste via conduit 22. The olens yare passed overhead from the wash zone via conduit 23 to fractional distillation zone 24 where the olefins can be separated into olelins lighter than those desired and heavy oleiins. The heavy olefins are removed via conduit 25 where they can be recovered as such or can be converted to alcohols by alkylation and oxidation followed by hydrolysis, e.g. with H2SO., or by the well-known oxo process or by the hydrobromation process, all of which are well-known in the art. The light olens are taken overhead via conduit 26 and passed to reverse displacement zone 18 wherein the light olcns react with a portion of the aluminum triethyl forming light weight aluminum trialkyls and ethylene. The effluent from zone 18 passes to stripper 27 via conduit 28. In stripper 27 the olens are separated from the aluminum compounds and are passed overhead via conduit 29 to fractionation zone 30. In zone 30, the ethylene is separated from the other light olens and is returned to displacement zone 6 via conduits 31 and 7. The remaining light olefns are taken `from zone 30 via conduit 32 back to reverse displacement zone 18. Since some water might be carried overhead from wash zone 19, it is within the scope of the invention to provide a drier, preferably in conduit 26.

Typical operating conditions for each zone will now be described.

In the growth reactor 2, the temperature can generally be varied from about 200 to about 300 F. and the pressure from about 1000 to about 2000 p.s.i.g. The residence time can vary from about 1 to 3 hours. Sulicient excess ethylene is utilized to obtain the desired pressure at the desired temperature.

The operating conditions in displacement zone 6 can vary also over a wide range. For example, the temperature can vary from about 180 to about 270 F., the pressure from about 200 to about 800 p.s.i.g. and the residence time from about 1.5 to about 6 minutes. Here again some excess ethylene is desirable. Frequently a catalyst such as nickel is used to promote the reverse displacement.

In reactor 8 the temperature can vary from about 120 to about 300 F., the pressure can be subatmospheric, atmospheric or superatmospheric, but in general Will be substantially atmospheric. The residence time can vary from about 0.25 to 30 minutes, but most generally will vary from 0.5 to 10 minutes. The conditions in the settling tank 12 will generally be dependent upon the conditions in the reaction zone 8.

The 2:1 complex is broken down to the 1:1 complex by heat and preferably under subatmospheric conditions since excessive heat can break down the 1:1 complex Therefore, the preferred conditions in zone 15 can vary from about 260 to about 375 F. and preferably from about 230 to about 260 F. The pressure will normally be from about to about 30 -millimeters of mercury absolute.

The fractional distillation column 23 will be operated to separate out those oleins lighter than the desired olefns. Since, in general, the desired olefns are C12-C18 and heavier, the column will operate with 200 F. overhead and 500 F. bottom temperature at about 10 p.s.i.g. A reux of light oleins can be utilized if desired.

In reverse displacement zone 18, the temperature can vary from about 400 to about 700 F., the pressure from about to about 300 p.s.i.g. and the residence time from about 0.5 to 1.5 seconds. Again, an excess of light olefins is desirable.

Typical operating conditions for stripper 27 is 90 F. top and 250 F. bottom temperature and 20 millimeters of mercury absolute. These temperatures will, of course, .again vary depending upon the particular light olens and metal alkyls. Again, a reflux can be employed.

The ethylene distillation zone 30 will generally operate at 20 F. top and 350 F. bottom temperature at 300 p.s.i.g. A reflux of ethylene is highly desirable here since only ethylene should pass overhead. In considering any specific operation, the excess of ethylene or light olens can be ignored since they will remain in the system.

The amount of desirable olens can be varied by controlling the ratio of pounds of light olens recycled per pound of detergent range olens recovered. This is shown in the table.

Weight percent olcns Low Carbon No. operation recycle recycle Sub total-.. 100.0 100.0 100.0

Total 117. 1 102. 0 151.6

Average ethylene additions per aluminumcarbon bond per growth path 2. 0 1. 0 0 Recycle mol light; olcus per mol product oletns 1/1 2. /l U. 6/1

The above data are shown in FIGURES 2, 3 and 4, respectively.

To further illustrate the invention, the typical operation from the table will be described in conjunction with FIGURE 1. The figures will be based on 2 mols of aluminum trialkyl effluent from the growth reactor 2. The material balance will be based on this figure. The description will also be illustrated wherein the metal alkyl is aluminum trialkyl and the growth olefin is ethylene. As previously indicated, excess ethylene will remain in the system and only additional ethylene will be added to maintain the material balance and pressure required.

Now referring to the figure, the reactor 2 is maintained at about 250 F. and under sucient ethylene pressure supplied via conduit 1 to maintain a pressure of 1500 p.s.i.g. The average residence time is about 1.5 hours. Two mols AlR'3 (wherein R is alkyl of random growth distribution) are passed to displacement zone 6 along with 6 mols of additional ethylene supplied via conduit 7. This zone is kept at about 225 F. and 500 p.s.i.g. for a residence time of about 5 minutes. The conversion, e.g. displacement is 99+% complete. We now have 2 mols AlEt3 (aluminum triethyl) and 6 mols of mixed olefins. This mixture is passed to adduction zone 8 which operates at about 240 F. and atmospheric pressure Where it comes into contact with 2 mols 1:1 complex of aluminum triethyl and tetramethyl ammonium chloride to form 2 mols of the 2:1 complex; the 6 mols of the full range olefins pass to separation zone 24 after first being waterwashed in in zone 19. The 2:1 complex is passed to zone 15 where it is heated to 250 F. at 5 millimeters of merury causing the 2:1 complex to decompose to the 1:1

complex and AlEta. The 1:1 complex is recycled back to zone 8 to again be formed into the 2:1 complex, the 2 mols of AlEt3 is passed to reverse displacement zone 18. The mols of mixed oleiins are separated in zone 24 into 3 mols of light oleiins and 3 mols of heavy oleiins. This unit operates with a 200 F. top temperature and 500 F. bottom temperature at p.s.i.g. with a small reux. The 3 mols of heavy olens can be recovered or converted to alcohols as previously indicated. The 3 mols of light olens pass to zone 18 along with 3 mols of light olens from zone 30 where it reacts with the 2 mols of AlEta from zone 15. About 50% conversion is obtained, thus giving an average euent of l mol AlEt3, 1 mol AJR?l (aluminum trialkyl), 3 mols ethylene and 3 mols light olens. The thermal reverse displacement zone 18 is operated at 550 F., 150 p.s.i.g. and a residence time of 1 second. The eluent from zone 18 is then separated in zone 27 into olens and aluminum compounds by operating with a top temperature of 90 F. and a bottom temperature of 250 F. at 20 mm. Hg absolute. This 1 mol of AlEt3 and 1 mol AlR3 are returned to growth reactor 2 where the process is repeated. The 3 mols of ethyl ene and 3 mols of light olens pass to zone 30 where the 3 mols ethylene are taken overhead and mixed with 3 additional mols of ethylene from fresh ethylene supply and the 6 mols passed to displacement zone 6. The 3 mols of light olefns are returned to reverse displacement zone 18 along with the 3 mols of light olens from zone 24.

From the above description, it can be seen that a material balance is maintained and while obtaining the olefin product as shown in the rst column of the table and plotted in FIGURE 2.

For simplicity, valves, heaters and condensers have not been shown since these are conventional items and can readily be supplied by the art. The operating condition for the other recycle ratios will be approximately the same as shown for the 1:1 recycle ratio shown except the separation steps which will be adjusted for the type of material being processed.

This invention has been described in a preferred embodiment, those skilled in the art will be able to make modifications to obtain the desired range of -olefins and/or alcohols without departing from the spirit and scope of the invention. For example, any build up of saturated hydrocarbons can be periodically bled ol the light oleiin` stream.

Having thus described the invention, I claim:

1. A process for altering the distribution of alpha-olens obtained from growth of low molecular weight aluminum alkyls with ethylene which comprises:

(a) displacing the growth reaction product from a growth reaction zone with a low molecular weight olefin to form high molecular weight alpha olens;

(b) separating the formed alpha-olens from the trialkylaluminum formed in (a);

(c) passing the aluminum trialkyl from (b) to reverse displacement zone;

(d) separating the oleiins from (b) into a low molecular weight fraction and a high molecular weight fraction;

(e) recovering the high molecular weight fraction from (d) as product;

(f) passing the low molecular weight fraction from (d) to said reverse displacement zone;

(g) separating the olens from the aluminum alkyl formed in said reverse displacement zone;

(h) passing the aluminum alkyls from (g) to said growth reaction zone;

(i) separating olens from (g) into low molecular weight oleiins and higher molecular weight olens;

(j) passing the low molecular weight oleins from (i) to (a); and

(k) passing the higher molecular weight olens from (i) to said reverse displacement zone.

2. The process of claim 1 wherein the metal of said metal alkyl is aluminum.

3. The process of claim 2 wherein the low molecular weight olefin is ethylene.

4. The process of claim 2 wherein the low molecular weight olen is propylene.

5. The process of claim 2 wherein the low molecular weight olefin is butene-l.

6. A process for producing alpha-olefins comprising:

(a) growing aluminum trialkyl with ethylene in va growth reaction zone to produce long chain aluminum trialkyls;

(b) displacing each 2 mols of aluminum trialkyl produced in (a) with 6 mols of ethylene to produce aluminum triethyl and long chain alpha-oletins;

(c) separating the product from (b) into aluminum triethyl and alpha-olefins;

(d) passing the separated aluminum triethyl from (c) to reverse displacement zone;

(e) separating the alpha-olefins from (c) into a low molecular weight fraction and a high molecular weight fraction;

(f) recovering the high molecular weight fraction from (e) as product;

(g) passing the low molecular weight fraction to said reverse displacement zone;

(h) separating the product of (g) into aluminum trialkyls and alpha-olefins including ethylene;

(i) passing the aluminum trialkyls from (h) to (a);

(j) separating the alpha-olens from (h) into ethylene and higher alpha-olens;

(k) passing the ethylene from (j) to (b); and

(l) passing the higher alpha-ole'ins from (j) to said reverse displacement zone.

7. The process of claim 6 wherein the rst displacement (b) is catalytic, and the reverse displacement is thermal.

8. The process of claim 7 wherein the catalyst is nickel.

9. The process of claim 7 wherein the ethylene addition per growth path is 2 mols ethylene per aluminum carbon bond of the aluminum trialkyl and the mol light olefin separated from heavy olefin product is 1:1.

10. The process of claim 9 wherein the aluminum triethyl is separated from olefins by adducting the aluminum compound with tetramethyl ammonium chloride adduct with aluminum triethyl in a 1:1 complex.

References Cited UNITED STATES PATENTS 2,863,896 12/1958 Johnson 26o-683.15 X 3,227,773 1/1966 Roming 260-683.15 3,278,262 l0/ 1966 Poe et al. 260-683.15 X 3,328,446 6/ 1967 Poe et al. 260-448 PAUL M. COUGHLAN, JR., Primary Examiner

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