US2473206A - Process of selectively polymerizing diolefins in an unsaturated and aromatic gasoline distillate - Google Patents

Description

Plum June 14,1949

PROCESS OF BELECTIVELY POLG DIOLEFINS IN AN UNSA'I'UBA'I'ED AND AROMATIC GASOLINE DISTILLATE Minor c. x. Jonea, Mountainside, and mam-a 0. Brandon, Elizabeth, N. 1., ausignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application May is, 1946,

Serialhlo. 670,835

2 Claims. (01. 196- 78)- This invention relates to a process of treating highly cracked gasoline distillates to obtain valuable high diene content polymers and stabilized motor fuel products.

Intensive cracking processes have been developed for producing large amounts of low boiling mono-oleflns and dioleflns needed for manufacture of synthetic rubber-like polymers. Also, in these processes are produced distillates boiling in the gasoline range, of about 100 F. to 450 E. containing considerable amounts of aromatic hydrocarbons mixed with unsaturated hydrocarbons that are very unstable. The complexity and high instability of these distillates created a problem of selectivity removing the unstable components and, in doing so, forming high diene number polymers that are particularly useful by virtue of their conjugated unsaturation.

An object of this invention is to provide a method of treating that results in the production of high diene number polymers having the propert of reacting with relatively large proportions of maleic anhydride, and similarly being a capable of combining with large proportions of sulfurv or other substances that add particularly to condugated double bonds.

The present invention is based primarily on the discovery that the presence of low boiling mono-oleflns in a distillate interferes with selec tive polymerization of higher boiling diolefln components in the distillate, especially if the amount of low boiling dioleflns is reduced, and the desired selectivity is obtained in a clay treatment of the distillate freed of low boiling olefins at temperatures in the range 250F. to 350"1. for a controlled contact period.

In accordance with the present invention, the conditions of the treatment with the catalytic adsorbent have to be carefully controlled to obtain the desired products. The average optimum temperature of the adsorbent during the treatment is in the range 250 F. to 350 F. The optimum space velocity of the gasoline distillate feed is within the limits of 0.2.to 1 volume of the dis- .tillate oil per volume of the adsorbent per hour.

A further object is to provide a. method of cracldng'of petroleum cracking occurs when the stocks are heated to temperatures in the range of 1000 F. to 1600" F. 'At these high temperatures, the cracking is beneficially-carried out in the presence of steam or a gas that prevents excessive coke formation. Substantial quan'tities of unsaturated gaseous hydrocarbonasuch as ethylene, propylene, butylenes, and butadlene, are produced; The gasoline distillates yielded contain large amounts of unstable hydrocarbons that readily form gums on oxidation; Among the unstable distillate components, compounds to be expected are typifled'by C5 to Cl: acyclic andcyclic dioleflns, such as pentadienes, cyclopentadiene, hexadienes, cyclohexadiene. and the like.

Clay treating processes known to havelu'aen used successfully on gasoline distillates produced under mild conditions of cracking were foundunsuitable for treating distillates produced under severe cracking conditions.

sumcient to maintain the oil in liquid phase.

Following the treatment, the stabilized distillate is separated from polymer and recovered by fractional distillation. v

Isoprene (2-methyl-L3-butadiene) is one of the low boiling C5 dioleflns formed in substantial quantities by intensive cracking, and is purposely separated from the gasoline distillates on'account of its usefulness'in the manufacture of synthetic rubber-like polymers. On clay treating the remainder of the gasoline distillates from which isoprene was removed, it was found thatthepolymer yield was high, but the diene numjber of the polymer was'rather low, thus indicat- .ing that a considerable amount of the remaining -Q a fdioleflns interpolymrized with mono-olefins.

e We then discovered'that if the distillates'are' first processed to separate not only the isopren'e but also low: boiiing-niono-olefins, such" as C5 to Ccoleiins, in cuts boiling below F., and the remainders of the distillates are clay treated under optimum conditions. the yield of high diene number polymer is more closely correlated to the diolefin contents of the feeds to the clay treat:

ment, and the treated distillates show considerable improvement in stability, all of which-indicate desired high selectivity in tionof-thedioleflns. f v I Accordingly, it is now demonstrated tobe advantageous to remove low boiling C5 to C6 olefins in removing a C5 diol'efin from the unsaturated and aromatic distillates produced by intense cracking before the distillates are-subjected to the polymerizadistillates, freed or the low boiling unsaturates, 5

.are contacted in liquid phase with the polymerizing catalyst. They may be percolated through a bed of solid catalyst in granular or lump form, so that the distillate oil in filtering down through the bed washes away polymer from the catalyst.

Floridin, iallers earth, Attapulgus clay, acidtreated clays, heat-treated clays, or other active siliceous adsorbents, such as zeolites, may be used as the polymerizing catalyst.

For the purpose of illustration, a mode or operation will be described with reference to gasoline distillates from a typical high-temperature steam-cracking process.

TABIE I 'hrprcar. Gamma Gammon Dara Fresh feed to cracking furnace, lbs./hr 10,322 Total feed to cracking furnace, lbs./hr 41,517 Steam feed to cracking furnace, lbs/hr--- 8,025

The following tabulated data were obtained from treatments of the naphtha distillates under comparative conditions with the following alterations of the distillates treated:

A. C5 diolefln (isoprene) removed, C5 to oiefins remaining in the naphtha.

B. Cs diolefin (isoprene) left in with Ca and Cs olefins.

0. C5 diolefln (isoprene) removed with C5 and Cs olefins. 7

TABLEII TABLE In Poems Paonacrs Conditions and feeds the same as in Table I! A B C v ma n g move w mmfim W to c. oienns Feed with o. to 0. Ole- Itemaining C; to 0| fins from in Feed Olelins Feed Polymart Yield, Vol. 8

per can 17 10 Via 'E' 2, Q 2 #23 1 it; viii mo F11 s1 s1 UIIII 78.5 51.3 64.8 teases/a it? .7 a m a." l l aleic Anhy do Val- '69 76 11a in g l 102 1115- Diane 150. from Maloic nnmlggfiige 81119... 11, 11 12 17, 19-

I. B. P.', e 296 440V 290 5 484 487 436 10 507 497 465 30 568 509 544 7, 626 608 606 Check Inspections.

cg. Bromine adsorbed by components that react with maleio ydride per gram of polymer sample.

The foregoing data, including check results, verify that removal of Ct to Ca olefins with the C5 diolefln made the aromatic-unsaturated naphtha susceptible to a more selective polymerization of diolefins remaining in the naphtha on treatment under optimum conditions with the active adsorbent catalyst.

Typical gasoline distlllates of intense cracking processes have aniline points of about 0 F. or lower. They generally contain 20 to 40 volume per cent aromatics, 50 to volume per cent mono-oleflns, and 10 to 20 volume per. cent diolefins. A substantial part of these mono-olefin and diolefins are C5 and Ca unsaturated hydrocarbons, which boil at temperatures below 140 F.

The polymers of increased diene number obtained bythe controlled selective polymerization of dioleflns in the naphtha distillates following removal of low boiling oleflns with low boiling diolefins are characterized by their ability to re- Nsrnms Paonncrs Faou CLAY Iaaarnvc or Bron- TEMPERATURE Cascnma Nsrnrns Drsmna'rns Operating conditions of clay treatment Temperature, F 300 Pressure, lbs/sq. in Feed rate, V./V./hr 0. 25 Clay Attapulgus Isop rene Isop rene Removed, c. Remaining m ggggg g Na m In to Ca Oleflns with C5 to C; p spections Remaining in 01am 0; to Us Oleflns I Food Product Feed Product Food Product A and Heat (ABTM), 1? 436 300 465 a sec 300 24s, Aniline Point, F- g 0- 0 2 21 0 0 Peroxide No 9 0. 4 10 0. 6 15 [0. 3 V 2' as 2 404 a I P30851101 added prior 50 (1181211182108;

act and combine with large quantities of sulfur supplied as elementary sulfur, sulfur halides, or other sulfurizing agents. The unsaturated polymers may be'fully or partly sulfurized before being compounded with natural or synthetic rubbers. They may be co-vulcanized with the rubbers, in which they serve as plasticizers or extenders. They have been found to be particularly useful as plasticizers or softeners of rubberlike copolymers of diolefins, such as the 001101;!- mers of styrene with butadiene or isoprene.

After separation of diolefins from the low boiling out of C5 to C6 olefins, e. g., by selective absorption of the diolefins with an ammoniacal cupreous salt solution, these Cs to Ca oleflns are advantageously added to the stabilized aromatic naphtha product of the selectivity polymerization treatment to obtain a high quality gasoline motor fuel.

It is to be understood that various modifications are intended to come within the spirit and scope of this invention as defined in the appended claims. I

We claim:

1. The process of selectively polymerizing dioleflns in an unsaturated and aromatic gasoline 25 distillate from a high-temperature cracking process, to obtain high diene number polymers and stabilized motor fuel, which comprises removing from the distillate an unsaturated hydrocarbon cut boiling below 140 F., passing the remainder of the distillate boiling above 140 E. into contact with catalytically active clay at an average temperature in the range of 250 F. to 350 F., said remainder of the distillate being in liquid phase and being contacted with the clay at a space velocity of 0.2 to 1 volume per volume of clay per hour, and recovering the thus claytreated distillate freed of unstable diolefins and a polymer of high diene number.

2. The process as defined in claim 1, in which diolefins are removed from the unsaturated hydrocarbon cut boiling below 140 F., and monoolefins of the out are added'to the clay-treated distillate freed of diolefins.

MINOR C. K. JONES. RICHARD C. BRANDON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 1,937,759 Herthel Dec. 5, 1933 2,067,030 Van Peski Jan. 5, 1937 2,162,717 Hancock June 20, 1939 2,422,627 Martin et a1; June 17, 1947