USRE22210E

USRE22210E - Polymerization of olefines

Info

Publication number: USRE22210E
Authority: US
Priority date: 1935-07-12
Publication date: 1942-10-27
Also published as: US2085524A

Description

0t 27, 1942- M. DE sl'Mo Erm.

PoLYMjEnIzAT'IoN or oLEFINss Original Filed .July 12. 1935 2 Sheets-Sheet l Oct. 27, 1942. M. DE slMQ ETAI.v

PoLYMEnIzATIon or QLEFINES Original Filed July 12,- 1955.

2 Sheets-Sheet 2 Ressued Oct. 27, 1842 22.210 roLYMEnlzA'rloN oF oLEFINEs Martin de Sim, Piedmont, and Frederick B. Hilmer, Berkeley, Calif., assig'nors to Shell Development Company, San Francisco, Calif., a corporation ot Delaware Original No. 2,085,524, dated June 29, 1937, Serial No. 31,075, July 12,1935. Application for reissue January 21, 1941, Serial No. 375,338

7 Claims. (Cl. 26o-94) Our invention relates to the -polymerization cf olenes under the catalytic action of polymerizing catalysts particularly those of the type of boron fluoride, such as aluminum chloride, zinc chloride, etc. In particular it is concerned with the polymerization of propylene and/or'betaiso-olefines. under the influence of a gaseous polymerization catalyst of the type of boron fluoride, which may include hydrogen fluoride, said beta-isoolenes having less than 9 carbon atoms per molecule and having the general formula Rl CH2=C/ wherein R1 and Re represent alkyl radicals and of which iso-butylene d j on,l cupo/ d is the first member. i

The catalysts which we intend to use in our process may be termed low temperature catalysts. They include all those which promote poly-4 action, the temperature control being one of the4 prime factors in obtaining uniform products, and it is another object to provide a continuous method for manufacturing polymers.

The polymers which we produce may vary in appearance from highly viscous liquids to rubdevelops. It has been recognized in the past, that it is essential to keep the temperature throughout the reacting mass within certain limits. For

instance, in the case of polymerizing iso-butylene j by means of boron fluoride the temperature should`be kept below 10 C.,- and it has been suggested to add solid carbon dioxide to the reacting mass to maintain an evenly low temperature.

We have found, however, that very often cooling with s olid carbon dioxide or external cooling is insufficient and does not lead to the formation of polymers of molecular sizes sufliciently large for many purposes.l Solid carbonv dioxide is not soluble in the reaction mass, and its effect is that of cooling parts of the mixture to temperatures as low as 80 C., and allowing at the same time the temperature in other parts to rise to above 10 C. at any one moment of the polymerization. The result is an uneven polymerization.

Our invention comprises improved methods ofA cooling, which depend for their successful execution on the immediate and even removal of the heat of polymerization and the maintenance of a desired reaction temperature with narrow limits. One such method consists of mixing with the olefines or a solution thereof a cooling liquid miscible therewith and having a boiling temperature not exceeding thatof the desired reaction temperature under prevailing pressures. As the polymerization takes place and the heat of reaction is developed, at least part of the cooling liquid evaporates, thereby absorbing heat. Because of the complete miscibility of the cooling liquid and the olefines, cooling is not only disber-like materials, depending upon the specific conditions under which they are manufactured. They are soluble or dispersable in hydrocarbon oils and can be usedfor plasticzers or constituents of lacquers or lubricating oils, etc.

It has been the practice heretofore to carry out the polymerization of oleiines with suitable catalysts by bringing the catalyst in contact with the liquid reactant. The olenes werepreferably kept yin solutions of an inert diluent, to prevent undue thickening of the product of the reaction, which might prevent the polymerization from going to substantial completion.

During the polymerization considerable heat G0 tributed evenly but also is effective immediately. There is no delay or rise of temperature involved, during which formation of relatively small and undesirable polymers can take place. We prefer to use the cooling liquid, Whose temperature under the conditions of reaction corresponds substantially to the desired reaction temperature. This permits the use of any quantity of cooling liquid in excess of the minimum required to hold the temperature at the proper level, without involving the risk of cooling to too low a temperature, which might unnecessarily retardthe reaction and result in undesirable products.

When polymerizing propylene and beta-isoolenes in contact with a catalyst of the type of boron fluoride, We have .found that extremely large polymers are formed if the polymerization temperature is kept within the range of 20 C. to C. the exact optimum temperature depending upon various factors involved in the polymerization. .It must be understood, however, that in order to obtaina uniform product, the temperature duri-ng an individual run requires control Within much closer limits, preferably within C. In our preferred procedure we mix the rolenes. or a solution thereof with an inert liquid whose average boiling temperature lies somewhere between 100 C. and 20 C., and whose boiling range is preferably not more than about 25 C. It shall be understood, however, that in some cases liquids may be used of a wider boiling range, such' as natural gasoline, or bottled gas, which may possess .boiling ranges as high as 200 C. but which are sufiiciently suitable cold solvent, very favorable results may l be obtained, the solvent sewing to keep the product of reaction in the liquid state for the purpose of removal. Concentrates of oleflnes containing 80% and more of active components can be polymerized without danger of incomplete ypolymervolatile. so that vsubstantial portions thereof evaporate causing the desired cooling.

Occasionally it is-practical to apply pressures above or below atmospheric in the reaction zone in order to adjust the boiling point of a particularly suitable cooling liquid. For example, if it is attempted to polymerize `propylene, having a normal boiling temperaturelof 47 C. in the liquid phase and at a temperature of about 30 C., ethaneat a pressure of about 150 lbs. absolute providesl a suitable refrigerant. When polymerizing iso-butylene whose normal boiling point is 8 C., or its homologues of even higher boiling points, superatmospheric pressures may be applied advantageously. Polymerizing under pressure permits the use of cooling liquids having much lower boiling points than the oleflnes, and

,large differences in boiling points between oleiines and refrigerant prevent substantial losses of oleilnfs during thevaporizaticn of the refrigerant.

In practice the mixture of oleilnes and cooling liquidis preferably chilled to approximately the correct reaction temperature and is kept under sufficient pressure. t"` insure its being in the liquid phase. A catalyst is added or 'the li'fuid is introduced into the vessel containing a catalyst, to allow the polymerization reaction to take place. During the reaction the pressure may be regulated to maintain the desired temperature. Stirring means may be provided to keep the mass kagitated for the purpose of causing quick and complete contact between catalyst and olenes.

When polymerizing in the presence of a gasreagents which can be'engaged in the reaction at any one time must necessarilybe relatively small, and the total amount of exothermic heat liberated thereby, being small,can be comparatively easily and quickly carried oi. 'I'hus the problem of cooling and maintaining an evenly low reaction temperature is greatly facilitated, and in many cases, when the polymerization is carried out by. spraying the polymerizable material in a finely divided state into an atmosphere of gaseous catalyst, the cooling by evaporation' of the volatile diluent can be replaced by other cooling methods described below.

Practical tests have proven that when spraying finely divided olenes either in the liquid or ization. oleflne concentrates containing more l than 80% active components occasionally yieldingproducts of higher molecular weights than are obtainable from dilute solutions of olenes.

Cooling liquid admixed to a concentrate can be so proportioned to leave after its vaporization a reaction product containing 80% or more of polymers, and solvents to cafry oil?y the product -can be added after the reaction is substantially nnished. 4

Continuous operation of the process is facilitated by spraying, the fine division of the olefines allowing for immediate contact with the catalyst thereby shortening the time of reaction and reducing delay and induction periods.

The spraying method also permits for the polymerization of gaseous oleflnesin the presence of gaseous catalysts, the cooling agent, if used, being the only liquid introduced into thereaction zone.

Suitable cooling agentscomprise inert liquids, whose critical conditions are well above the temperatures and pressures of the reaction zone, and whose boiling range under suitable pressures isl within orslightly below the desired range of the reaction temperature. Most of them are normally gaseous and include compounds such as ethane, propane, overhead vapors from natural gasoline stabilization containing mostly ethane and propane, monochlor methane, diiluordichlor methane, etc., and their mixtures.

The quantities of cooling agent required to maintain the proper temperature cannot be accurately specified. It is'deslrable tohave at least enough of it present to prevent the temperature at anytime during the reaction from going above the desired reaction temperature, which in the case of polymerizing iso-butylene with vboron fluoride is of the order of 30 C. In any event the amount of cooling liquid `should be suflicient so that the latent heat available by its vaporization is at least as great as the heat of polymerization.

Inorder to make the process continuous it is necessary that a suitable solvent 'or non-solvent carrier liquid carry away the products of polymerization from solidfsurfaces in or around the reaction zone. If a solvent for polymers is used, it may be incorporated into the oleiines prior to polymerization, or it may take the form of `a scrubbing liquid which continuously washes the i surfaces touched by the polymers, or else it may form a pool into which the polymers fall. Many of the cooling agents also act as good solvents for the polymersand an excess of cooling agent may well serve to keep the polymers in the liquid form. Hydrocarbons such as propane, pentanes,

' and lower mono-alcohols, glycols, certain esters.

gaseous form in contact with the catalyst in the absence of a self-evaporating cooling agent against a cold solid surface in the presence of a suitable solvent, or into a moving stream of a etc., can be used successfully for scrubbing purposes, provided the liquid has a wetting power towards the walls of the reaction vessel, which is greater than that of the polymers. Such carrier liquidsy not only permit the successful removal of polymers from the surfaces surrounding in which gaseous 2, itismixed ina not applicable to undissolved polymers in thel absence of such carrier liquids because of extreme stickiness of said polymers.

Insoluble carrier liquids can be easily separated I from the polymers by evaporation, either before or after the polymers are blended with other hydrocarbon oils, such aslubricating oil.

The products of polymerization, if produced according to our invention, -amounts of components having molecular weights in excess of 10,000. These high molecular weight substances are no longer viscous sticky fluids like the lower homologous members of the group but are elastic, rubbery materials.

In Figure 1, one possible form of carrying out the process of this invention is shown which enables the continuous production of olefine poly- -mers in contact with a gaseous ,catalyst by spraying liquid oleiines mixed with a cooling agent into an atmosphere containing the catalyst. Figure 2 represents a vvariation of the process of Figure 1,

catalyst in the .presence of a spray of cooling agent.

Referring to Figure 1: Iso-butylene or any of the suitable oleilnes previously described is introduced into the system from a source not shown, through line I. As it proceeds to chilled coils T 3 with liquid propane or other suitable cooling agent. The mixture is cooled in a chiller 2 to about 50 C., and is then released through a valve 4 and a spray nozzle 5 into a reactor 6.

Instead of a spray nozzle, which at times may have a tendency to clog, a rapidly rotating plate can be employed onto which the liquid mixture drops after being discharged from the pipe line I. Theliquid is immediately thrown off in the form of a fine spray.

Boron fluoride, or its equivalent, alone or in dilution of an inert gas, is introduced through a line 1, a blower 8 and a line 9 into the reactor 6. The reactor B is a tall cylindrical vessel, prefer- -ably with a cone bottom. The discharge end of the line 9 may be tangentially disposed in relation to the reactor 6, so as to impart to the boron fluoride-bearing gas in the reactora rotating motion. The spray of iso-butylene and propane from nozzle 5 descends as a fine rain in countercurrent to the ascending boron fluoride. As the iso-butylene polymerizes, heat is developed and evaporation of, `propane occurs, which keeps the temperature slightly below 30 C. The height of the reaction vessel is so chosen'as to permit for enough time of reaction to substantially pol-V ymerize the iso-butylene during its descent. The time of lreaction depends a great deal on temperature, purity of iso-butylene and condition of boron fluoride. The. presence of' small quantities oi' hydrogen fluoride, moisture or other impurities in the boron lfluoride may greatly accelerate the polymerization reaction.l l

Propane vapors containing boron fluoride are withdrawn from reactor 6 through a. reflux line I0 at the top of the reactor. They pass through a. scrubber Il in counter-current to a suitable solvent for polymers, such as pentanes, which descends through the reflux line and flows downward in a film on the inside wall of the reactor. Means, such as a troughl or distributor 31, may

be provided to distribute the film of descending pentanes over the entire wall area, which posiolefines are injected into the contain substantial till tively prevents accumulation of polymers and plugging of the reactor. Likewise the scrubber and the reflux line are continuously washed and freed from depositing polymers.

The relative position of the iso-butylene intake and reflux line is of some importance. In order to preventlthe escape of a substantial portion of unreacted vaporized iso-'butylene into the reflux line and scrubber, lthe reflux line is preferably connected to the reactor at a point considerably higher than the iso-butylene intake. By this arrangement rising iso-butylene vapors are caused to polymerize and, drop before reaching the reflux line.

From the scrubber II propane' vapors proceed to chilled coils I2 and thence to a separator I3. Propane is liquefied, separated from gases containing boron fluoride, and is pumped by a pump Il to a T l, in which it is mixed with fresh isobutylene. Part or all of the propane may be di- Yverted through line I5 and be sprayed into the reactor 6 at one or several convenient points.

l A solvent, such as pentane, which flows downward on the inside wall of the reactor 6 accumulates in the cone-bottom I6 to form a. pool. Isobutylene polymers descending through the atmosphere of boron fluoride, are taken up in the pool and dissolved. At times it may be desirable to heat the liquid in the pool to accelerate the rate of dissolving polymers and to reduce the viscosity of the resulting solution. This can be achieved by means of a heating coil 3E. To provide agitation and'to promte further polymerization of a small portion of unreacted or only partly polymerized iso-butylene, a gas containing some boron fluoride may be blown through the solution by means of line I1. If desired all of the make-up boron fluoride may be introduced at this point, in which case the valve in line 9 is closed. The gaseous boron fluoride rises immediately to the surface 'of the pool and into the gaseous space of the reactor 6.

The solution of polymers is continuously withdrawn from the reactor 6 by a pump I8, which forces it through a coil I9 in a furnace 2li. A light high-grade neutral oil may be introduced into the stream of the polymer solution in a T 2l, which is preferably located between the pump IB and the coil I9. The mixture, after passage through the coil I9, is introduced into a fractionator 22, from which small amounts of propane plus some boron fluoride are taken overhead as vapors; the solvent is removed as a liquid side stream, if desired, and polymers, dissolved in the neutral oil, are withdrawn as a bottom stream. The vapors from the fractionator passing through a conduit 23, join the vapors from the scrubber II at a point 24, and flow together to thechilled coils I2. The separated solvent is cooled in a cooler 2-5 and goes into a storage tank 2G. The pump 2I conveys it from storage to the top of the scrubber II through a line 28, or directly into the cone-bottom I6 of the reactor 6 through a line 29. Instead of pentanes, other solvents for polymers of suitable boiling range can be employed, such as benzene, carbon tetrachloride/ chloroform, dichlorethane, etc.l

The mixture of polymers, separated in the fractionator 22, goes from the fractionator to storage through a line 3l).

Boron fluoride4 taken from the top of the separator I3 may be returned to the reaction zone by means of the blower B, either directly through a line 3|, or by way of a purifier 32 ,and lines I3 and 3|. Impurities may be drawn ci! through valved line 35.

It may at times be 'useful to shorten the delay or induction period preceding the polymerization by introducing a trace of boron fluoride into the liquid stream of. iso-butylene at a point ahead of the reactor. Usually the propane issuing from the separator I3 contains traces of boron iluoride, which materially reduces the induction period. The lcontamination of thecooling agent at the operating pressurelof the polymerization zone which substantially corresponds to the desired treating temperature and is below the boilv ing temperature of the oleilnes, injecting the sowith the catalyst may even be large enough to necessitate placing the vmixing T 3 past the chilled coils 2 rather than ahead of it, as shown in the drawings, in order. to avoid excessive prepolymerization in the coils and `plugging or the `spray device.

If polymerization is to be carried out byv spraying polymerizable oletines against a cold surface in the' absence of a cooling agent, the wall of the reaction vessel B may be chilled from the outside,

for instance, by providing a jacket and evaporat...

ing therein, a suitable refrigerant. A quantity of solvent for polymers may be added to the olenes, providedthis does not interfere with the formation of the desired rubbers', elastic polymers, said n quantity being large enough to keep the product of polymerization in suiciently liquid state to allow its flowing down the wall. The scrubber Il may in this case be eliminated since there are very small quantities of ascending vapors capable o! carrying unreacted olefnes and the probability of clogging the vapor exit line is very small.

When polymerizing gaseous iso-olenes, a reactor arranged as shown in Figure 2 may be used'. Boron uoride and iso-olefines are introduced through lines M and I5, respectively, into the lower part of a reactor 43, in such a manner that substantially instantaneous mixing in the reactor takes place. Cooling liquid is sprayed through a line 38 and an atomizer 39 into the upper part of the reactor I3. The spray of cooling liquid descends in counter-current to the rising mixture of oleiine and boron fluoride gases. As polymerization occurs, cooling liquid evaporates and rises While non-vaporous polymers fall downward into a pool 4D consisting of pentanes or the likeV in the bottom of the reactor I3. Vapors consisting of cooling agent, unreacted iso-oleiines and boron fluoride are withdrawn through reflux line 4l and are scrubbed in scrubber I2 by the descending pentanes. f

The pressure in the reaction vessel may be varied to suit conditions, higher pressure accelerating the polymerization and raising the boiling range of a given cooling agent.

While the type of apparatus described is particularly suited for the polymerization of liquids and gases in the presence oi.' gaseous catalysts, it shall be understood that other types of apparatus applicable to the use of liquid and solid.

catalysts can be designed. We do not intend to lution in a state of ne division into the reaction zone containing a gaseous catalyst of the group consisting of boron iluoride and hydrogen fluoride, to eiIect polymerization of the olenes, whereby heat is liberated and the liquid solvent is vaporized, and maintaining an excess of the liquid solvent in the solution entering the polymerization zone over the quantity of the solvent which is evaporated due to the heat of reaction.

2. 'I'he process of claim 1 in which the oleiines are substantially in the liquid state during poly- `v` merization.

3. The process of claim l in which the surface of the reaction zone is-continually washed with an organic liquid having a greater wetting power for the surface than the products of the poly- ,merization l I limit our invention to any particular apparatus.

the only limitations o1' our invention being those disclosed in the following claims.

We claim as our invention: l. In the process of polymerizing tertiary base olefn'es of less than 9 carbon atoms by treatin same-with an active uoride to produce rubber' like polymers, the improvement comprising forming `a liquid solution of the oleilnes in an inert lower-boiling liquid hydrocarbon solvent f or the' olefines, the solvent having a boiling temperature 4. 'I'he process of claim l infwhich the surface of the reaction` zone is continually'washedwith a lower ketone of the type of acetone. I

5. The process of claim 1 in which the surface of the reaction zone iscontinually washed with a solvent for the products of the polymerization.

6. In the process of polymerizing tertiary base oleilnes of less than 9 carbon. atoms by treating same with an active uoride to produce rubberlike polymers, the improvement comprising forming a liquidsolution of the` olenes in an inert lower-boiling liquid hydrocarbon solvent for the olenes, the solvent having a boiling temperature at the operating vpressure of the polymerization zone which substantially corresponds to the desired treating temperature and is -below `the boiling temperature of the olenes, the said inert lower boiling solvent for olelines being also a solvent for olefine polymers, injecting the solution into the reaction zone while agitating to finely distribute same, said zone containing a gaseous catalyst of the group consisting of boron fluoridey and hydrogen fluoride, to effect polymerization ofthe olefines, whereby heat is liberated and the liquid solvent is vaporized and maintaining an excess 0f the liquid solvent in the solution entering the polymerization zone over the quantity of the solvent which is evaporated due to the heat of the reaction.

7. In the process of polymerizing tertiary base oleilnes of less than 9 carbon atoms by treating same with an active iiuoride to produce rubberlike polymers, the improvement comprising forming a liquid solution of the oleiines in an inert lower-boiling liquid hydrocarbon solvent for the olenes, the solvent having 'a boiling 'tempera-