Oct, 22, 1946.V G. c. BAILEY 2,409,727 lPRODUCTION OF OLEFIN POLYMERS .Filed Jan. 30, 1942 wm ATTORN EY 2,409,727 Patented Oct. 22, 1946 UNITED STATES PATENT OFFICE 2,409,727 PRODUCTION OF OLEFIN `POLYMERS Grant C. Bailey, Bartlesville, Okla., _assignor to Phillips Petroleum Company, a corporation of Delaware Application January 3o, 1942,seriá1`N0.4'2s,966 5 Claims. (Cl. 26o-683.15) 2 'I‘his invention relates to the catalytic poly merization of mono-oleñns, and more particularly tothe production of tetra-isobutylene from iso butylene and di-isobutylene. Tetra-isobutylene is a mono-oleiin containing 16 carbon atoms per molecule. Tetra-isobutyl ene exists in several isomericY forms possessing highly branched carbon structures and each In the direct polymerization of an oleñn to a polymer having a desired molecular Weight, such as the polymerization of isobutylene to tetra-iso butylene, for example, polymers of both higher and lower molecular weight are formed. For any given catalysts,V conditions can be found which structure possesses an active olefinic bond mak give an optimum yield of the desired polymer, but the higher and lower polymers Will be pres ent in lesser, but substantial amounts. ing it useful in the preparation of chemical de rivatives of this particular oleñn species through gives the product analysis of the liquid obtained various'reaction procedures. Hydrogenated tetra isobutylene possesses a high octane number, mak from a run in which gaseous isobutylene was polymerized over activated fioridin at room tein ing it useful as fuel of very low volatility inin ternal-combustion engines. It has a solidiiying temperature below _100° C., making it useful at very low temperatures as a hydraulic fluid, for example. In many such applications, it is desirable to usea product having a particular molecular weight and boiling range, together with 20 unique characteristics as previously suggested; tetra-isobutylene is especially suited for some of these applications. The catalytic polymerization of mono-oleñns ` This is illustrated by the data in Table I, which perature. ` Table I Component:` ` Per cent of total liquid Di-isobutylene ____________________ _- 17 Tri-isobutylene ___________________ __ 50 Tetra-isobutylene _________________ __ 17 « Penta-isobutylene _________________ __ 5 ~- Hexa-isobutylene Hepta-isobutylene _______ „_ ________ __ 0.5 Residue __________________________ __ 9.5 to higher-molecular-weight products is Well known. Isobutylene is one of the most reactive mono-olefins, and its polymerization using vari ous catalysts and conditions and its polymeriza 1 ________________ __ 100.0 Orthophosphoric acid also readily polymerizes isobutylene. The productv which was . obtained when isobutylene was polymerized with ortho tion products have been the subjects of many in vestigations.V These products range from di-iso 30 phosphoric acid at 30° C. comprised essentially di- and tri-isobutylene, while at 130° C. seven butylene, which is in the boiling range of gasoline, isomeric polymers were produced. through oils, to viscous, rubber-like, and non Sulfuric acid readily brings about the poly elastic resinous products. In any given reaction, .merization of isobutylene to products containing the product usually contains a series of polymers of different molecularn Weights, each successive 35 di-isobutylene, tri-isobutylene, and higher poly mers. At relatively low temperatures and loW chance in molecular weight corresponding to one molecule of monomer. The average molecular acidv concentrations, relatively high proportions of dimer are produced. As the temperature and weight of a polymer'product depends upon the acid concentration are increased, the proportion catalyst and the polymerization conditions. Us ing highly active catalysts, such as aluminum 40 of higher-molecular-weight polymers, trimer and tetramer especially, and the complexity of the chloride, the proportion of products of different polymer are increased. At still higher tempera molecular Weights follows a probability distri tures, the average molecular weight oi the prod bution around the average molecular weight. In such cases the average molecular weight is a uct decreases, as a result of extensive changes in the lower the temperature the higher the average Metal halide catalysts, such as aluminum chloride, boron fluoride, and the like, are very ac function of the temperature of polymerization, 45 the hydrocarbons during polymerization. molecular weight. ` In many‘cases where the polymerization cata tive, bringing about the rapid polymerization of isobutylene to relatively high-molecular-weight lyst is less active, such a probability distribution is not found. The rates of the formation of vari 50 compounds. At temperatures of -80 to _100° C., isobutylene is converted to resinous or plastic _ ous polymeric `formsmay vary so greatly with polymers of very high molecular weight. At 80° temperature that true equilibrium conditions are C.,`the polymer product contains oleiins ranging never attained and the composition of the prod from gasoline to lubricating oils, or dimers to uct depends upon the comparative rates of the 55 decamers and sometimes higher. With increase competing reactions. 3 2,409,727 4 in temperature of reaction, there is produced a decrease in the average molecular weight of the product and an increase in the complexity of the polymer or in the other reactions accompanying simple polymerization. In all such catalytic polymerization systems, acid of such strength can be used to selectively absorb isobutylene from a mixture of normally gaseous hydrocarbons. Upon heating such a sul furic acid extract to about 100° C., isobutylene is polymerized to a product containing 80 per cent or more di-isobutylene. one polymer is often produced in somewhat When the hydrocarbon stock charged through conduit H is rich in iso butylene, treatment in polymerization unit l2 higher proportion, but always with substantial amounts of polymers of higher and lower molecu lar weights accompanying it, The preparation of a product containing only trimer or only tetramer is thus not'possible in the conventional polymeri zation system. However, it has been found pos sible by proper selection of 'a catalyst and a reac tion system to limit markedly the reaction so that dimer alone is produced in high concentration. Two factors contribute tohi'gh maximum yields with sulfuric acid as described will convert iso butylene to a product containing more than 90 per cent di-isobutylene. I have -round that good yields of di-isobutylene can also be obtained from isobutylene by treating an isobutyle'ne-containing mixture with phos phorus pentoxide catalyst in the ytemperature range of about -5 to +15° C. and preferably from (l to ’10° C. As-the temperature is decreased of dimers as contrasted to the lower »maximum below _5° C., the rate of polymerization of iso yields of any higher-molecular-weight product. bu'tylene to di-isobutylene decreases very rapidly, Firstly, there is no polymer having a molecular 20 and as the temperature of polymerization is in weight ‘lower than the desired product. 'Sec creased above 15° C., the ‘proportion of dimer in ondly, the conversion Vto each successively higher _molecular-weight vpolymer requires greater cata jlyst activity than the previous conversion. the Iproduct decreases rapidly, trimer becoming the main product. Using polymerization tem Therefore, careful 'selection of catalyst and con- , ‘ditions minimizes the'formation ‘of 'higher poly peratures in the range of 0 to 10° C., 50 to'60 per cent yields of dl-isobutylene can be obtained. «Elñuent from polymerization unit E2 is passed through conduit £3 controlled by valve -35 to sep arator id. Any unreacted isobutylene in the ef íiuent from unit 'l 2 is >separated therefrom in sep mers. Several combinations of catalysts and con ditions have >been found by various workers whereby di-'isobutylene can be prepared from iso `butylene in yields ‘of 80%-01‘ greater. arator i5 and passed through conduit l5 con >I have 'now found that `di-isobutylene can 'be trolled by valve S6 to‘conduit AIl and thence to converted'to tetra-‘isobutylene in high yields using polymerization unit l2. When material lower boiling 'than isobutylene is charged to my process through conduit VH and is substantially inert under the conditions `in unit I2, such material 4phosphorus pentoxide ’as 'a catalyst. This ‘inven tion affords a method of converting isobutylene to tetra-isobutylene in high yields and more `readilythari was previously possible. This is ac complished by using a two-step process compris is removed from'separator 'ifi and from my proc ess through conduitsfbll and i6 controlled by valve 3l. When 'it is desirable to have such material ing polymerizing isobutylene to di-isobutylene under conditions that produce high yields >of di present during -the conversion of isobutylene in unit i2, 'it can be >recycled ‘from separator I4 ‘through conduits "54 and l5 controlled by valve isobutylene, separating this dimer from other products and converting it »to tetra-isobutylene 'usingrphosphorus pentoxide asä catalyst. 38, when‘valve v3'! inßconduit lß’is wholly or‘partly ìIt is an object of my invention to convert'a low `boiling olñn to a higher-boiling olefin. closed. Tri-isobutylene produced -in unit `I2 is removed from separator Ylil through conduit 58 controlled by valve 63 and‘may be lfurther treated ` Another object of my invention is to produce an olefin polymer having a desired molecular `as appears desirable. Usually I prefer to pass 'weight in high yields íroman oleñn'of Vlower'mo such `trimer material ¿to depolymerization unit lecul'a'r weight. ‘|9, the operation of which is subsequently de fAno'th‘e'r object is to -rapidly polymerize a scribed. -Sometimes minor amounts of tetra mono-oleñn to a lpolymer of desired molecular 50 4isobut'yleneare also Aproduced'in unit l2 and such vweight 'in high yields. material lmay be removed from separator I4 Another object is ’to produce high yields of >through `conduit "Se controlled by valve fS5 as a -tetra-isobutylene. desirable product of my process. Further objects and advantages of my inven Polymeric `Vhydrocarbons boiling above the tion will’be apparent from t‘heaccompanying dis- ` ' tetra-‘isobutylene range `are ‘removed -from sepa closure. rator |11 through‘conduit l? andywhen such ma My invention'will now be more particularly de erial is considered as undesirable in my process, scribed and 'exempliiied in connection with the it can be removed therefrom through conduit I8 drawing'which is a schematic flow-diagram illus controlled by valve 39. When, however, such trating specific embodiments of the’invention Vfor co high-boiling polymeric ‘hydrocarbons can be de the production of high yields of desired polymeric polymerized to useful materials, for example, they hydrocarbons lfrom monomeric hydrocarbons. are passedthrough valve ’llû'in conduit kI'l to de Isobutylene, or a 'hydrocarbon mixture con polymerization unit I9 when valve '39 in conduit taining essentially'isobutyle'ne and other hydro >I3 is 'wholly or `partly closed. In unit i9 such carbons -substantially inert under theconditions ‘ polymers along with any trimer or tetramer at which isobutylene is subsequently converted, passed thereto are depolymerized under suitable is'passe'd’through conduit ll controlled by valve ‘IU to >polymerization unit l2, wherein isobutylene is 'treated yaccording to any of the processes'well known in the art for the production therefrom of di-‘isobutylene in optimum yieldswith only small amounts of other polymeric hydrocarbons being produced. Sulfuric acid having a strength be tween ‘60 and 75’per cent is a particularly advan tageous-catalyst'for'such a conversion. -Sulfuric conditions of temperature, pressure, and'reaction time, in the presence or absence of catalytic ma terials for .promoting depolymerization Vreactions to produce monomeric oleñns that can be ad vantageously used, such Vas isobutylene, tetra isobutylene and even ole’ñn hydrocarbon poly mers in the lubricating-oil range. 475 The de polymerization of high-molecular-weight ole 1in polymers to lower-molecular-weight hydro 2,409,727 5 mospheric pressure is usuallypreferred in opera carbons is well known.,` Such depolymeriza tions result in the regeneration of the original tionsi of this kind at the lower temperatures, althoughhigher pressures can be used to advanl-j tageand pressures as high as 1000 pounds per4 square inch gage produce desirable results. The reaction time for carrying out this `polymeriza olefin from which the polymer was prepared to gether with low-molecular-weight 1 . olefin@` poly mers, such as >those in the gasoline boiling range. In these depolymerizations, negligible amounts tion step is -preferably in the range between three hours Jand seven hours although reactionptimes Generally, the amount of polymeric material boiling above >di-isobutylene in the eiiiuent of outside of this range have been found toV produce polymerization unit l2 will be quite small, and all 10 substantial amounts of the desired product. When short reaction times are employed in unit such material may be charged to the depoly-` 25 at any giventemperature< Within the range disclosed, less di-isobutylene is polymerized¢per Eflluent from the depolymerization unit `I9 is pass and, therefore, more di-isobutylene is re passed through conduit >6E) controlled by valve 59 to separator 55. Inseparator 55iany low-boiling 15 cycled to unit 25 for further conversion to tetra offcarbonaceous residues and hydrogen result. merization. ` Y . . „ . isObutylene. Long reaction times in unit 25 favor higher conversion per pass operation Vwith an inherent less amount of recycle of unpolymerized di-isobutylene to unit 25. However, prolonged catalyst life and other factors may make it de material having less than four carbon atoms per molecule is removed from the system through conduit 56 controlled by- valve 51. Usually the amount of this material will be ‘very small and generally negligible. Isobutylene contained in >the effluent from unit i9 'i's'passed from separator 55 through conduit 2| controlled by valve 43 to sirable'to work with short reaction times and less , polymerization per pass. i In unit 25 it is desirable to secure intimate. conduit Il wherein it is admixed with fresh contact between the phosphorus pentoxide .cat charge stock to polymerization unit I2. A di-iso butylene fraction, which will sometimes consti 25 alyst and hydrocarbon material.` To facilitate in timate `mixing,fmaterials which aid in dispers? tute an appreciable portion of the eflluent from ing the phosphorus pentoxide may be used, such depolymerization unit .l9,'is -removed from sepa as sand or lamp black. Efficient contact between rator 55 through conduit 22 and passed through catalyst and reactants is highly important in the` polymerization step in unit 25. valve 48 to c‘onduit 24 and thence through valve 4l. to polymerization unit 25 subsequently de scribed herein, ’ , f . The di-isobutylene charged to polymerization ' unit 25 is preferably quite pure and particularly Any hydrocarbon material having’ a higher free from oxygen-containing compounds, such boiling range than di-isobutylene and including material in the lube-oil boiling rangewis removed from separator 55 through conduit 20 y,controlled as are readily formed when di-ísobutylene is eX 35 posed to air or oxygen. The presence of oXy gen-containing compounds in the di-isobutylenev by va'lve‘42.""Material‘boiling abovethe lube-oil feed to unit 25 greatly decreases the rate of poly merization therein and necessitates the use of larger quantities of phosphorus pentoXide cat alyst to produce satisfactory yields than when suchu'o’xygen-containing ’compounds are absent from unit 25. range', including tars" ‘and high boilingundepoly merized material from unit i9, is removed from separator 55 through conduits 63 controlled by valve 58. In somevinstances it will be. desirable vto return material `removed through conduits 20V and/or 53 to the depolymerization.unit> |91for. conversion to additional quantities of di-isobuty-` lene, either directly or indirectly, by means not.. Under the more favorable conditions discussed herein the phosphorus pentoxide catalyst is not shown inthe drawing. Such operation is par 45 rapidly deactivated. The useful life of the cat alyst depends `upon the rate at which it is de ticularly advantageous when-it is desirable` to activated by absorption of water and the rate at charge as much di-isobutylenetoV polymerization which sludge-like materials are built up by reac-V unit ‘25’ as possible. l ~ ’ ~ ‘ ~ substantially .fpure tion with oxidized olefins or other reactive im In polymerization0 unit . di-,isobutylene ` is` contacted ‘with phosphorus. 50 purities. herein. In some instances it will be desirable> to charge di-isobutylene to my process from some` A ` ‘ " or any other suitable means well known to the outside source. This is conveniently done by means of conduit 23` controlled by valve 41.. art, and is then recycled to polymerization unit 25 by conduit 30 controlled by valve 46. When Phosphorus pentoxide ischarged to polymeriza tion unit 25 through conduit 26 controlled by valve 44. _It may, however, be admixedwith` hydrocarbon chargefstock to unit _25 by means 60 not shown before said stock is admitted to unit 25 and under conditions which do not promote appreciable conversion,Í of said hydrocarbon charge. Inunit v25 phosphorus _pentoxide is con , :Effluent from polymerization unit 25 is passed through conduit 2l .controlled by valve 451:0 sep arator` 28. Phosphorus pentoxide `catalyst is re moved from the-liquid by filtration, centrifuging, pentoxide under conditions for the, productionbf optimum yields of tetra-isobutylene as disclosed used catalyst has become so spent as to be un economical for conversion of additional di-iso-butylene, such spent material or> spent catalyst is removed from my process through conduit 3l controlled by valve 52 whereafter it may be dis posed of or treated as appears desirable. Usu ally such‘spent material is regenerated to active tacted with di-isobutylene charged, thereto‘in a 65 catalytic material and> recharged to unit 25 and/ or to‘any other catalytic process or unit employing temperature range between about 0° C. and*4 100°A C. and underv a suiiicient pressure that the hydro phosphorus pentoxide as a catalyst’. carbon charge will be in the liquid phaser, Within this temperature range the reaction is essentially dimerization of diisobutylene. vNo polymers higher-boiling’than tetra-.isobutylene are usually dpi-isobutylene is separated and recycled to poly merization unit 25 through line 29 controlled by found in the product. Although the polymeriza- » tion >reaction in unit 25 ,proceeds more `rap idly‘at 'highertemperatures arange between> aboutZO" C. and 60° C. is usually preferred. 'At Unreacted valve 49. Desired tetra-isobutylene is removed from separator 28 through conduit 33 controlled by valve 50. It is readily obtained in a state of " high purity since no isododecene or iso-eicosene` is produced by the polymerization in 25,1. ïthereby affording a simple separa-tion in separa-i 2,409,727 7 8 tor 28; During an extended operation of my process small amounts of polymeric material Table V higher boiling than tetra~isobutylene maybe pro Volume per cent duced inunit 2-5 and can be removed from sepa rator 28 through conduit 32 and from my process through valve 5|. When such material is easily Di-isobutylene ______________________ __ 50 Tetra-isobutylene ___________________ __ 50 depolymerizable to a-lower-molecular-weight pol 100 ymer such as di-isobutylene, or to isobutylene, Examples III and IV show that phosphorus pentoxideA polymerizes di-isobutylene to tetra-iso it is preferably charged to depolymerization unit I9»wherein a conversion is carried out as described 10 butylene over a wide range of temperature and herein. My invention is furtherillustrated by the fol that the reaction proceeds more rapidly at higher temperatures than at lower. lowing examples which are recorded to disclose specific applications of my invention and are not intended to limit unnecessarily the scope or util ity of the principles of my invention in anyway. EXAMPLE V Twenty parts by weight of freshly prepared di isobutylene and 1 part phosphorus pentoxide were agitated at room temperature for 4 hours. The product was filtered and distilled. The fol EXAMPLE y I lowing composition was found: A steel pressure autoclave which was equipped with an eíiìcient stirrer and an internal thermo 20 Table VI couple was thoroughly cleaned and dried using a stream of dried nitrogen. Phosphorus pen Volume per cent toxide was introduced into the autoclave under Di-isobutylene ______________________ __ 25 anhydrous conditions. Tetra-isobutylene ___________________ __ 75 A charge stock consist ing of 76 per cent isobutylene and 24 per cent 25 isobutane was forced into the autoclave during a 5-hour period. The autoclave was cooled with ice, and the charging rate adjusted so that the internal temperature was held between 0 and 2° C. The unreacted isobutylene and isobutane were re 100 EXAMPLE VI The run cited in Example V was repeated using di-isobutylene which had become partially oxi dized by contact with air. The product had the leased from the reactor, and the polymer prod uct filtered and fractionated. The product hadv following composition: the following composition: Table VII Table Il Component: 35 Volume per cent Di-isobutylene ______________________ __ 58 Tri-isobutylene ______________________ _ _ 17 Tetra-isobutylene __________________ ___ Higher polymers ________ ___ ______ _____ 'I 18 40 Component: Volume per cent Dl-isobutylene ____________________ ___ 96 Tetra-isobutylene __________________ __ 4 100 Examples V and VI show that, in order to pro duce high yields of tetraisobutylene from di EXAMPLE IIy isobutylene using phosphorus pentoxide, the di isobutylene must be substantially free from oxi dation products. The run cited in Example I was repeated except the temperature of the reaction was held at about 35° C. Fractionation of thev product showed it to >have the following composition: of> my process may be found desirable in connec 100 Many variations in the apparatus or operation tion with specific embodiments and various modi ñcations may be readily made by one skilled in the artI in the light of the present disclosure. The Table III Component: `various polymerizationu steps may be operated Volume 17ery cent Di-isobutylene ____ __ ________________ ___ 20 Tri-isobutylene ____________ _____________ 60 Higher polymersl _______________ ________ 20y continuously or intermittently in batches as may be found most desirable for any particular case and-f the particular conditions used. The drawing is, ofcourse, diagrammatic and the application y of my invention on a commercial scale will neces 10o sitate the use of much equipment such as pumps, EXAMPLE III heaters, coolers, fractionators, and the like not shown in detail but. which may be readily applied and'adapted for any particular installation by one 159‘C. for seven hours. The catalyst was removed 60 skilledin the` art. separators, such as I4 and 28, willv advantageously comprise several individual by ñltration, and distillation of the product units such as ñlters, fractional distillation col showed it to have the following composition: umns, strippers, accumulators and the like equip Table IV ment well known in the separating art. The gen Volume per cent eral process and possible material flows have Di-isobutylene _________________ _____ __ 16 . been disclosed and this together with the specific 'I‘wenty parts by weighty ofv di-isobutylene and l 'part phosphorus- pentoxide were agitated at lll-' Tetra-isobutylene _______________ ______ 84` examples are .believed tok be suñicient to Serve as efficient guides. 100 EXAMPLE IV Twenty parts by weight of di-isobutylene andîl part phosphorus pentoxide were contacted at 100‘." C. for 3 hours. The material was cooled, filtered and distilled. The liquid. product had the follow ing composition: I claim: 70 l; A process for producing high-boiling hydro carbons from lower-boiling hydrocarbons, which comprises passing di-isobutylene to a polymeriza tion zone and contacting said di-isobutylene in the liquid phase in said zone with phosphorus pentoxide at a temperature between 0° C. and 2,409,727 100° C. for a period of time such that an optimum amount of tetra-isobutylene is produced. 2. The process of claim 1 wherein the reaction time for the polymerization is between three and seven hours. _ 3. In a process for producing high~boiling hy drobar-bons from lower-boiling hydrocarbons, the 10 tetra-isobutylene, and removing said fraction from the process. 4. A process for the production of tetra-iso butylene by polymerization of di-isobutylene Without the formation of substantial amounts of tri-isobutylene, Which comprises subjecting di isobutylene in the liquid phase to the action of phosphorus pentoxide at a temperature within polymerization zone, contacting said di-isobuty the range oi approximately 0° C. to approxi lene in the liquid phase in said zone with phos 10 mately 100° C‘. phorus pentoxide at a temperature between 0° 5. A process for the production of tetra-iso steps which comprise passing di-isobutylene to a C. and 100° C. for a period of time such as an op timum amount of tetra-isobutylene is produced, passing eñiuent from said polymerization zone butylene by polymerization of di~isobutylene without the formation of substantial amounts of tri-isobutylene, which comprises subjecting di to a separating means, separating therefrom a 15 isobutylene in the liquid phase to the action of fraction rich in di-isobutylene and returning said fraction to the polymerization zone, separating also therefrom a fraction comprising essentially phosphorus pentoxide at a temperature within the range of approximately 20° to approximately 60° C. GRANT C. BAILEY.