US 2909574 A
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Oct. 20, 1959 R. A. wooDLE 2,909,574
MANUFACTURE OF ALKYLATED ARONIATIC HYDROCARBONS Filed Jan. 29, 1958 Taal.
niteci States Patent MANUFACTURE or ALKYLATED ARoMAHC HYDRoCARoNs Robert A. Woodle, Nederland, 1,`ex., assgnor to Texaco Inc., a :corporation of Delaware 4This invention relates to the manufactureof chemicals. More particularly, this invention relates to the ymanufacture of alkylated aromaticV hydrocarbons.
In accordance with one embodiment this invention relates to the recovery of straight chain olenic hydrocarbons from gaseous streams containing the same and the utilization of the recovered'straight chain olenic hydrocarbons for the alkylation of aromatic hydrocarbons. In accordance with another embodiment this invention relates to a unitary process for the recovery of normally gaseous straight chain oleiinic hydrocarbons and the manufacture of alkylated aromatic hydrocarbons wherein the recovery of the normally gaseous straight chain olenic hydrocarbonsand the manufacture of alkylated aromatic hydrocarbons is carried out substantially simultaneously.
Accordingly, it is an object of this invention to provide a process for the manufactureof alkylated aromatic hydrocarbons. a V 1 Still anotherV object of this invention is to provide an improved process for the manufacture `of alkylated aromatic hydrocarbons such as ethylbenzene, cumene, isocumene, xylenes and the like.
Yet another object of this invention is Vto provide a process for the recovery of normally gaseous olenic hydrocarbons such as ethylene and propylene and the n-butenes, or mixtures thereof, such as occur in petroleum renery streams and the. utilization of the recovered straight chain oleiinic hydrocarbonsin an alkylation operation for the alkylation ofhydrocarbons, such as aromatic hydrocarbons. t t
`I-Iow these and other objects of this invention are achieved willbecome apparent in the light of the accompanying disclosure made with reference to the accompanying drawings wherein Fig. 1 schematically illustrates one embodiment of the practice of this invention. directed to the manufacture of an alkylated aromatic hydrocarbon and wherein Fig. 2 schematically illustrates another embodiment of the practice of this invention directed to the manufacture of an alkylated aromatic hydrocarbon.
In accordance with this invention it has been discovered that alkylated hydrocarbonsl such as alkylated aromatic hydrocarbons are advantageously produced byV employing an aromatic hydrocarbon as the desorbent or desorbing mediumI in the desorption of adsorbed straight chain oleiinic or unsaturated hydrocarbons from an adsorbent containing the same, andthen employing the resulting desorption efuent comprising desorbent (aromatic hydrocarbon.) and the desorbed straight chain oleiinic hydrocarbon under conditions such that the straight chain olenic or unsaturated hydrocarbon reacts with the desorbent (aromatic hydrocarbon) to form the corresponding alkylated aromatic hydrocarbon.
By straight chain olenic hydrocarbon is meant any aliphatic or acyclic or open chain unsaturated hydrocarbon which does not possess side chain branching. Representative straight chain oleinic hydrocarbons are 2,909,514 Patented oct. 20,1959,
Y 2 ethylene,`propyle ne, the n-butenes, the nr-pentenes, the n-hexenes, the n-heptenes, the n-octenes and` the like.y Other straight chain oleinic hydrocarbons may also be suitably employed in the practice of this invention. These other unsaturated straight chain hydrocarbonsinclude butadiene, pentadiene and the like as well as the straight chain acetylenic hydrocarbons.
The selective adsorbent employed in the practice of this invention for the adsorption of straight chain unsaturated or olenic hydrocarbons include the natural or synthetic zeolites or alumino-silicates such as a calcium aluminosilicate which exhibit the property of a molecular sieve, that is, matter made up of porous crystals wherein the pores of the crystals are of molecular dimension and are of substantially uniform size. In general, the zeolites. may be described as water-containing alumino-silicates having the general formula (R,R2)O.Al2O3.nSiO2.mH2O wherein R may b e an alkaline earth metal, such as calcium, strontium or barium, or even magnesium, and wherein R is an alkali metal suchV as sodium or potassium or lithium. Thesematerials, after the removal of substantially all of the water therefrom, retain their crystalline structure.
A particularly suitable solid adsorbent for straight chainunsaturated hydrocarbons, indeed for all straight chain hydrocarbons, is a calcium alumino-silicate, ap` parently actually a sodium calcium alumino-silicate, manufactured by Linde Air Products Company and designated Linde Type 5A Molecular Sieve. The crystals of this particular calcium alumino-silicate have a pore size or opening of about 5 Angstrom units, a pore size sufficiently large to admitstraight chain hydrocarbons such as ethylene, propylene, the n-butenes and the like, to the substantial' exclusion of the non-straight chain hydrocarbons, e.g., naphthenic, aromatic, isoparanic and isooleiinic hydrocarbons. This particular selective adsorbent is available in various sizes, such as in the form of 1/s, or 1/16 diameter pellets, or as a finely divided powder having a particle size in the range 0.5-5.0 microns. Also suitable as a selective adsorbent for the selective adsorption of gaseous straight chain unsaturated hydrocarbons is an alumino-silicate, apparently actually a sodium alumino-silicate, manufactured by Linde Air Products -Company and designated Linde Type 4A Molecular Sieve. The crystals of this particular aluminosilicate have a pore size of about 4 Angstrom units, a
' pore size sufficiently large to admit relatively low molecuylar weight unsaturated hydrocarbons, such as ethylene and propylene, to the substantial exclusion of the higher molecular weight straight chain hydrocarbons, such as n-pentane, the n-pentenes and the like.
In the practice of this invention solid selective adsorbents such as zeolites which have a rigid threev di-V mensional anionic network and interstitial dimensions suf-v ciently large to adsorb straight chain unsaturated or olenic hydrocarbons but sutlciently small to exclude the v non-straight chain hydrocarbons are suitable. The natu- 4 gmelinite, harmotome and the like, or suitable base exchange modifications of these zeolites, may be employed in the practice of this invention.
Referring now to the drawings and particularly to Fig. 1 thereof which schematically illustrates one emas ethylene and propylene is introduced via line 11 intol adsorber 12 wherein itis contacted with a suitable adsorbent which p refererxtially` adsorbs straight chain olenic hydrocarbons over lnon-straight chain hydrocarbons.l
There issues from adsorber 12 via linel 14 a gaseousV efuent stream now having a reduced amount of straight chain oleinic hydrocarbons therein. When the adsorbent material within adsorber 12 has become substantially saturated with straight chain olenic hydrocarbonsnthe introduction of the gaseous stream containingstraight chain olefinic hydrocarbons via line 11 is halted and there is introduced into the adsorber 12 via lines 15, 16 and 11 an aromatic hydrocarbon as a desorbing medium or desorbent. The thus-introduced aromatic hydrocarbon is employed to heat the selective adsorbent therein and to desorb the adsorbed straight chain olenic hydrocarbons from the adsorbent material Within adsorber-12.
As a result of the above-indicated desorption operation there is recovered from adsorber 12 via line 18 a gaseous desorption eilluent comprising the aromatic hydrocarbon (desorbent) and the resulting desorbed straight chain olenic hydrocarbon (desorbate). The desorption eflluent is then introduced via line 18 into alkyla-tion reactor 19 wherein it contacts a suitable alkylation catalyst and wherein the unsaturated straight chain olefinic hydrocarbon serves to alkylate the aromatic hydrocarbons associated therewith.
vFrom reactor 19 there is recovered via line 20 an alkylation reaction eluent comprising unreacted aromatic hydrocarbon and the resulting alkylated aromatic hydrocarbon. This alkylation effluent is introduced via line 20 into fractionator 21 wherein it is fractionated into an overhead stream via line 16 containing the unreacted aromatic hydrocarbon which is recycled to adsorber 12 via lines 16 and 11 to eifect the desorption of additionall straight chain olefinic hydrocarbons. There is also recovered from fractionator 21 as product a bottoms fraction, via line 22 comprising the resulting alkylated aromatic hydrocarbons.y
Referring now to Fig. 2 of the drawing which schematically illustrates another embodiment of the practice of this invention and wherein the same reference numerals employed in connection with Fig. 1 are employed to designate similar pieces of equipment, a gaseous stream comprising a straight chain unsaturated or olenic hydrocarbon is introduced via line 11 into combination adsorber-reactor 12. Adsorber-reactor 12 contains the adsorbent which preferentially or selectively adsorbs the non-straight chain olenic hydrocarbon and also contains a suitable alkylation catalyst. The special adsorbent and alkylation catalyst may be admixed together to-form a substantially homogeneous admixture in the form of a fixed bed or a iluidized bed or a falling bed, or the adsorbent may be maintained separately from the alkylation catalyst within the adsorber-reactor 12 as two separate beds.
When the gaseous eluent removed via line 14 fromv the adsorber-reactor indicates that the adsorbent therein is substantially saturated with straight chain olenic hydrocarbons a suitable aromatic hydrocarbon is introduced thereinto via lines 15, 16 and 11 and the conditions in adsorber-reactor 12 adjusted so as to eiect substantially simultaneously desorption of the adsorbed straight chain olelinic hydrocarbons from the adsorbent therein and alkylation of the thus-introduced aromatic hydrocarbon by the resulting desorbed straight chain olenic hydrocarbon. The resulting alkylation reaction ellluent is recovered via line 18 and introduced into fractionator 21. From fractionator 21 there is recovered an overhead fraction via line 16 comprising unreacted aromatic hydrocarbon which is recycled to adsorber-reactor ration conditions, more .fully described" hereinafter, so
I as to effect the most economical useof the materials employed and for ease of control.
The adsorptive separation or adsorption of the straight chain olenic or unsaturated hydrocarbons by the solid selective .adsorbent may be carried out at any suitable temperature, such as a temperature in the range 50-800 F., and at any suitable pressure, such as a pressure in the range 040,000 p.s.i.g. and higher, the temperature and pressure being adjusted withl respect to the hydrocarbon fraction undergoing treatment depending upon whether or not it is desired to-maintain the hydrocarbon fraction undergoing separation in the liquid phase or in the vapor or gaseous phase. Liquid phase adsorption may be carried out by simply slurrying or contacting the solidselective adsorbent with the hydrocarbon fraction being treated, followed by separation or decantation of the treated hydrocarbon eluent, now substantially free of or having a reduced straight chain hydrocarbon con.
tent. Liquid phase adsorption may also be carried out lby percolating the liquid hydrocarbon fraction to be treated through a bed of solid adsorbent material.
It is the usual practice, however, to carry out the adsorptive separation operation in the gaseous phase, that is, to maintain l the hydrocarbon fraction undergoing 1- treatment in the vapor phase during the adsorption operation. In such an operation any suitable method for effecting gas-solid contact may be employed, for example, -a fixed bed, a moving bed or a fluidized bed or a gas-entrained mass of selective adsorbent may be employed during the gas phase adsorptive separation operation. |After sufcient time, the solid adsorbent is separated from the resulting treated hydrocarbon fraction and the resul-ting solid adsorbent is then subsequently treated in accordance with the practice of this invention to desorb the hydrocarbon content therefrom.
The desorption of the adsorbed hydrocarbons (straight chain olefinic hydrocarbons) from the solid adsorbentmaterial may be made at any suitable temperature and pressure. For example, the desorption operation may be carried out at a pressure in the range 0-10,000 p.s.i.g.
` In accordance with the practice of this invention, however, the desorption operation is carried out in the gaseous phase, that is, the gaseous desorbinlg lluid and the resulting desorbed hydrocarbons are both present in the resulting desorption etiluent in the gaseous or vaporous phase. Accordingly, the desorption temperature and the desorption pressure are adjusted to maintain the desorbent and the desorbed straight chain unsaturated hydrocarbons Y in the gaseous phase. Generally a desorption pressure in the range 10-2,000 p.s.i.g. is suitable. `It is sometimes' tion. Usually a temperature in the range 40G-900 F. is
employed during the desorption operation. It is generally preferred, however, to carry out the desorption operation at an elevated temperature in the range 425 800 F. The desorption temperature employed, however, should not be excessively high, for example not greater than about 1100 F., particularly in the instance wherein a material such as Linde Type 5A Molecular Sieve, that is, a calcium alumino-silicate, is employed as the selective adsorbent since these rather high temperatures are eX- cessive and lead to the destruction of the adsorbent, presumably by collapse of the crystal structure, with resultant loss of the selective adsorption properties of this particular adsorbent.
Various aromatic hydracarbons may be employed in the practice of this invention to effect the desorption of the adsorbed straight chain olenic hydrocarbon. The aromatic hydrocarbon employed as desorbent is also at the same time alkylatable by the resulting desorbed straight chain olenic hydrocarbon. Suitable aromatic hydrocarbons include benzene, and the monocyclic alkylated hydrocarbons such as toluene, the xylenes, ethylbenzene, mesitylene, hemimellitene and the like. It is preferred, however, in the practice of this invention to employ benzene as the aromatic hydrocarbon for the desorption of the adsorbed straight chain olefinic hydrocarbons.
Various alkylation catalysts, liquid and solid, may be employed in the practice of this invention. Also, the alkylation reaction may be carried out in the liquid phase although gaseous phase alkylation is preferred. Suitable alkylation catalysts include chromia on HF-treated silicaalumina and phosphoric acid treated kieselguhr. Other suitable alkylation catalysts for effecting the alkylation of aromatic hydrocarbons, such as benzene or toluene and the like, by reaction with a straight chain unsaturated or olenic hydrocarbon, such as ethylene and propylene, are known.
The following example is illustrative of the practice of -this invention.` A gaseous stream ysuch as is recoverable in a petroleum renery operation, comprising a major or minor amount of propylene, eg., in the range 5-70% by volume, is introduced into contact with a sodium calcium alumino-silica-te molecular sieve type adsorbent, such as Linde Type 5A Molecular Sieve. The propylene thusintroduced into contact with the adsorbent is preferentially adsorbed. After the selective adsorbent is substantially saturated with propylene it is contacted with a gaseous stream of benzene at a temperature in the range 300-700 F., to eifect desorption of the adsorbed propylene. During the desorption operation it is desirable to employ a substantial molar excess of benzene such that in the resulting desorption eluent the benzene comprises a major portion thereof, e.g., benzene to propylene mol ratio in the range 4-20z1.
A mixture comparable to the aforesaid desorption mixture, such as a mixture comprising 20,000 cc. of benzene and 1600 grams of propylene, was passed over -a solid type alkylation catalyst, chromia on HF-treated silicaalumina at a temperature of 250 F. yand a pressure of about 500 p.s.i.g. and at a space velocity of 2.0 v./hr./v. (basis solution). The resulting alkylation reaction eluent was recovered and stripped to 194 F. leaving 5675 cc. of a high boiling residue. This high boiling residue was further distilled to yield a distillate product which had a distinct cumene odor. Tests indicated that the bulk of the propylene was used up in alkylating the benzene admixed therewith. Similar results were achieved with a zinc oxide-zinc chromite on HF3 silica-alumina catalyst.
As will be apparent to those skilled in the art in the light of the foregoing disclosure many modifications, alterations and changes are possible in the practice of this invention without departing from the spirit or scope thereof.
1. A method of manufacturing an alkylated aromatic hydrocarbon which comprises contacting a gaseous stream containing a straight chain olenic hydrocarbon and other hydrocarbons with an -alumino-silicate molecular sieve type adsorbent which selectively adsorbs straight chain hydrocarbons to the substantial exclusion of non-straight chain hydrocarbons to adsorb said straight chain olefinic hydrocarbons from said gaseous stream, contacting the resulting adsorbent, now containing substantially only straight chain olenic hydrocarbon adsorbed therein, with a monocyclic aromatic hydrocarbon under conditions to effect desorption of the adsorbed straight chain oleiinic hydrocarbon, contacting the resulting desorption effluent comprising said aromatic hydrocarbon and the resulting desorbed straight chain olenic hydrocarbon with an alkylation catalyst under suitable conditions to eiect alkylation of said aromatic hydrocarbons by said straight chain olenic hydrocarbon.
2. A method in accordance with claim 1 wherein the straight chain olenic hydrocarbon adsorbed by said adsorbent is ethylene.
3. A method in accordance with claim 1 wherein the straight chain olenic hydrocarbon adsorbed by said adsorbent is propylene.
4. A method in accordance with claim 1 wherein said desorption operation and said alkylation reaction are effected Ksubstantially simultaneously.
5. A method in accordance with claim 1 wherein said desorption operation and said alkylation reaction are eiected substantially simultaneously by admixing said adsorbent with a solid type alkylation catalyst.
6. A method in accordance with claim 1 wherein said desorption operation and said alkylation reaction are effected substantially simultaneously by admixing said adsorbent with chromia on HF-treated silica-alumina as a solid type alkylation catalyst.
7. A method in accordance with claim 1 wherein said desorption operation and said alk-ylation reaction are effected substantially simultaneously by admixing said adsorbent with phosphoric acid-treated keselguhr as a solid type alkylation catalyst.
8. A method in accordance with claim 1 wherein said aromatic hydrocarbon is benzene and said olenic hydrocarbon is propylene vand wherein said desorption operation and said alkylation reaction are effected substantially simultaneously.
9. A method in accordance with claim 1 wherein said molecular sieve type adsorbent has a pore size opening of about 4 Angstrom units, a pore size opening suiciently large to admit low molecular weight unsaturated hydrocarbons such as ethylene and propylene to the substantial exclusion of higher molecular weight straight chain hydrocarbons.
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