US2335406A - Treatment of hydrocarbons - Google Patents

Description

Noir. 30, 1943A. AQR. GoLDsBY ETAT.

TREATMENT OF IIYDROCARBONS Filed Jan. 50, 1940 THEIR ATTORNEYS Patented Nov. 30, 1943 TREATMENT F HYDROCARBONS Arthur R. Goldsby and Eugene E. Sensel, Beacon, N. Y., assignors, by mesne assignments, to The Texas Company, New York, N. Y., a corporation of Delaware Application January 30, 1940, Serial No. 316,322

13 Claims.

This invention relates to the treatment of hydrocarbons and particularly to treatment with an isomerization catalyst to improve the anti-knock value and volatility.

In pending application, Serial No.- 282,114, filed June 30, 1939, we have disclosed a process for treating straight run naphtha wherein hydrocarbon constituents of naphtha are subjected to contact with an isomerization catalyst in the presence of a large proportion of` a low boiling isoparaflin hydrocarbon, such as isobutan'e.

The present invention relates to such a process, with particular reference to its application to the treatment of normal pentane, or a hydrocarbon fraction consisting essentially of normal pentane,

for the production of isopentane.

It has been proposed heretofore to isomerize certain normally gaseous hydrocarbons and lower boilingnormally liquid hydrocarbons, such as normal butane and normal pentane, to correspending isoparafiins by contacting the normal para'ns in the liquid or vapor phase at temperatures of Zero to 200 C., with certain anhydrous metallic halides, such as chlorides, bromides, etc., of aluminum, zinc, iron, zirconium, tin, barium, columbium, tantalum and boron, and small amounts of hydrogen halides, such as hydrogen chloride, as promoters. AIt has also been proposed to subject gasoline of boiling range of about 130 to 190 F. to isomerization in the presence of aluminum chloride and hydrogen chloride at temperatures of about 150 to 200 C.

Normal butane may be successfully isomerized to isobutane in the presence of anhydrous metallic halides and hydrogen halides, without a sub- Bll-683.5)

ence of a large proportion of added isobutane, no trace of the complex compound exists and the catalyst is recovered as a dry powder. Moreover, the formation of high boiling material ismaterially reduced.

The reactions involved are not fully understood. However, it is thought that the isobutane preferable to use hydrogen chloride.

stantial amount of side reactions, providing correct operating conditions are used. In the case of the higher boiling normally liquid hydrocarbons, considerable diiilculty is encountered due to cracking and/or other types of-side reactions, whereby substantial deterioration of the catalyst is experienced and a substantial proportion of high boiling material outside of the gasoline boiling range is formed.

It has now been found that the side reactions and accompanying deterioration of the catalyst which normally occur with the higher boiling normal paraifms, may be substantially inhibited or minimized by carrying out the .isomerization operation in the presence of a large proportion 4of a low boiling isoparaflin, such as isobutane. Thus, experiments have shown that when normay inhibit the cracking and the resultant ,formation of unsaturated hydrocarbon fragments or olens, which, either as such or as conversion products, react with the aluminum halide to form the complex. In`addition the hydrocarbon fragments or olens vmay react with the isobutane rather than with the catalyst. The catalysts which are useful in the process include any. of

the active isomerization catalysts, such as metallic halides. preferably used in the presence of small amounts of promoters, such as hydrogen halides.

alysts are contemplated, for practical purposes aluminum halides, such as aluminum chloride, and aluminum bromide, are preferred. Likewise, any of the hydrogen halide promoters, such as HC1, HBr, HI and HF, 'may be used, but it is The metallic halide catalyst may be in granular, solid, or lump form, or in the case of AlBrs at temperatures above 208 F. in liquid form, or supported on a solid adsorbent, such as synthetic and natural clays, silica gel, pumice, brick, coke, activated alumina, and activated carbon. The hydro-v gen halide promoter may be added as such or may be generated in situ from the metallic halide by adding the required amount of water,steam or alkyl halide which reacts with the metallic halide.

The process may be carried'out in a batch or continuous type of operation, and preferably in a continuous operation. The process is preferably conducted as a cyclic operation in which the isobutane or a butane fraction of the reaction mixture is recycled together with any portion or all of the hydrogen halide promoter, as well as all or any portion of the unconverted'normal pentane.

The amount of catalyst and promoter will vary, depending on the type of operation used. The percentage of promoter may' be varied within Wide limits, say 0.1 to 10% by weight of the normal pentane-isobutane solution being treated. A concentration of 0.5% appears to be satisfactory for liquid phase isomerization, but a higher concentration of the order of around 2 t0 3% may be desirable for gas phase isomerization.

The invention is not restricted to'any particular temperature and pressure since the process may be operated successfully at temperatures and pressures selected from quite wide ranges. Thus, temperatures may range from about room temperature to about 300 F., although av temperature in the range of about to 230 F. is preferable. In general, as the temperature is While any of the anhydrous metallic halides which will function as isomerization catalso 'be employed. For liquid phase I percentage of promoter the optimum conversion to isopentane. It is contemplated that the contact increased, more isobutane is'required to eliminate the formation of the hydrocarbon-catalyst compleit.

The operating pressure will depend upon l the temperature as well as upon the type of operf temperature may be used in gas phase operation in order to obtain the advantage of a greater through-put, although pressures from atmospheric up to the equilibrium vapor pressure can operation a pressure in excess of the equilibrium vapor pressure is employed.

The proportion of isobutane used is influenced by the operating conditions and the nature of the charge. It is contemplated that the ratio by volume of isobutane to normal pentane charged maybe as much as 5:1, or higher, the higher ratios being advantageous when using higher temperatures and higher percentages of promoter and catalyst. As periments referred to below, weight ratios of 2: 1 and about 421 parts of isobutane per part of normal pentane have been found eifective. Y

'I'he contact time for the mixture being treated will depend upon the temperature, pressure and used, which variables may be chosen to give time may be around 1 to 4 hours for liquid phase operation. For vapor phase operation the contact time may be of the order of from 1 to 15 minutes.

The following examples comparethe results obtained when isomerizing normal pentane with and without the presence of a substantial proportion of added isobutane at temperatures of` 160l and 200 F., respectively. The results were obtained inv batch experiments using powdered anhydrous aluminum chloride as a. catalyst. A small amount of water was added to generate the promoter, i. e., hydrogen chloride.

indicated in the ex-4 gcam 00nd As the foregoing data indicate, where the conversion was effected in the absence of isobutane there was substantial conversion of the catalyst to the complex compound, namely, 5.16% in Experiment' l and 4.84% in Experiment 3. 0n the other hand, in the comparative runs, where isobutane was present, no -complex formation was noted. Substantial vconversion of normal pentane to isopentane occurred in each experiment. In Experiments l and 3, where isobutane was absent from the charge there was substantial formation of hydrocarbons boiling above normal pentane, while in the comparative experiments, where isobutane was present in the-charge, no higher boiling hydracarbons were formed.

We have foun at it is advantageous to eiect isomerization4 of normal pentane inthe absence of appreciable quantities of higher molecular weight hydrocarbons. The individual normal paraiiin hydrocarbon apparently isomerizes most effectively at a temperature lower than that nec--f mixture fromA naphtha to isomerization'under similar conditions and at the same temperature,

very little conversion of normal pentane to iso-A pentane occurs.

` spent catalyst may be withdrawn` The invention will be understood further from the accompanying drawing showing a flow diagram for carrying vention.

Referring to the drawing: I A charge comprisingA n-pentanels introduced through a pipe I to a catalyst chamber 2. -Isobutane or a mixture of iso and normalbutane is introduced through a pipe 3. ,Any partially from the catalyst chamber through a pipe l. l v

The reaction products are transferred from the upper portion of the catalyst chamber through a pipe 5 to a stabilizer or` separator wherein any catalyst carried over with the hydrocarbons may be separated and withdrawn, The separator, or the reaction products entering the separator, may be cooled to facilitate precipitation of .the catalyst.' The hydrocarbons' are passed from the separator 6 to a fractiohator 1.

The'fractionator 1 is advantageously-operated so as to remove hydrogen chloride and other gaseous4 constituents which may be discharged from the separator. If the gas removed com- `'prises essentiallyhydrogen chloride, it is ad-V Experiments Temperance F-- 16o 16o zoo 20o Time hours-- 4 3.1 4 2 CHARGE IN' GRAMs 343 1,24 550 l, 375 Y 0 1, 100 182. 2 129.9 175. 1 WMeth-; 4. 2 3 4. 1 Catalyst converted to HCL.. 10.4 7. 4 10. 1 Catalyst eilective as auch.-- 122. 5 171. 8 1%. 5 165 Hydrogen chloride generated.. 6. 1 8. 5 6. 1 8. 3

PRODUCTS IN-GRAMS Hydrocarbon layei...;` 1, 155 1, 690- 1, 140 1, 610+.V Catalyst layer ..5 190 179 186 170+ Y Hydrocarbons recovered .pot cent.. 94.35 98. 89 03. 14 07.01!- Hydrocarbons convtedtoeomplex A pelit..` 5.16 0.11) 4.84 (Lw LOW TEMPERATURE DISTILLTION 0E HYDO- CARBON LAYER- EXPRESSED A8 MOL PEB CENT Boiling bei ummm -5.- o. o o. o 0.1 o, Isobutalio... 5 74. 3V 57. 6 74. ,0. 2 3. 8 5. 1 0.

21. 9 15. 6 m. (i m. 2. 3 5. 3 5. 5 4. 12. 1 0. 0 10. 5 0.

sa 7s so vantage'ously recycled The hydrocarbons withdrawn fromvthel botto the reaction vessel 2.

tom of the fractionator 'I are passed to a fractionator 8. This fractionator is advantageously operated so as to remove an overhead fraction comprising butanes. A side stream is removed comprising isopentane; while the fraction drawn off from thev bottom of the frac Ationator comprises .normal pentane.

As indicated, the butane fraction may be onducted, 'all or in part, through pipesl and' Il' and thus recycled to the reaction vessel 2. Likewise, the normal pentane fraction may be trans-A ferred, all or in part, through the' pipe I0 for recycling to the reaction vessel.

Thus, in actual practice', thev fractionation of the reaction products may be regulated so as to remove the 'promoter'.` isobutane, normal out the process of the inl or a butane fraction.

butane and normal pentane, which are recycled, .While the remaining product, comprising-isopentane, is withdrawn from the system. The isopentane so Withdrawn is advantageously disposed of as a blending stock in the manufac-I ture of aviation gasoline.` Isomerization of normal pentane to isopentane raises the octane number (CFRM) from approximately 60 to 93. It also increases the Volatility, since normal pentane has a boiling point of 96.8 F., whereas isopentane boils at 82.4 F.

Consequently, the isopentane produced in the process is of particular benet when blended with gasoline fractions for the production of aviation gasoline.

While recycling the unconverted pentane has been mentioned, it is contemplated that this may not be necessary. As indicated by the experimental data set forth above, the concentration of isopentane in the pentane fraction of the product may be around 76 to 85% so that recycling of the normal pentane may not be necessary.

It is also contemplated that mixturesof isobutane and normal butane may be recycled to suppress deterioration of the catalyst and resultant formation of the catalyst-hydrocarbon complex. 4Moreover, it is contemplated that the make-up isobutane, in a continuous system, may be obtained by the addition of normal butane In such case normal butane is converted to isobutane with formation of an equilibrium mixture of normal and isobutane.

Although aluminum chloride was used in the above-described experiments, eutectic or other mixtures of two or more of the aluminum halides can be used. Other isomerization catalysts besides the anhydrous aluminum halides can be employed. Mixtures of hydrogen halides can be used as promoters. Alkyl halides or mixtures of alkyl halides, acyl halides or mixtures thereof,

aryl halides or mixtures thereof, water, steam,v

alcohols, aldehydes, ketones, organic acids, and other oxygenated compounds can also be used as promoters.

Obviously many modiiications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and-therefore only such limitations should be imposed as are indicated in the appended claims.-

We claim:

1. A process for isomerization of normal pentane which comprises subjecting normal pentane` in the presence of a substantial proportion of added hydrocarbon comprising isobutane to contact with aluminum chloride and hydrogen chloride at a temperature of 130 to 300 F. for a period of time of around one minute to not in excess of four hours and thereby 'forming a reacted hydrocarbon mixture rich in isopentane, the amount by weight of the aforesaid-isobutane being added being substantially in excess of the Weight of pentane charged and suilicient to substantially reduce cracking, and retard catalyst deterioration.

2. A process for the isomerization of a hydrocarbon feed consisting essentially of normal pentane which comprises Vcontinuously passing a stream of said feed through a reaction zone containing a metallic halide isomerization catalyst maintained under isomerizing :conditions at a temperature not in excess of about 300 F., continuously introducing to said zone isobutane in the ratio of isobutane to normal pentane maintained in the reaction zone is about 2 to 4 parts of isobutane to l part of pentane by weight.

4. A process for the isomerization of a hydrocarbon feed consisting essentially of normal pentane which comprises continuously passing a stream of said feed through a reaction zone containing a metallic halide isomerization catalyst maintained under'isomerizing conditions, continuously introducing to said zone isobutane suincient in amount to maintain va substantial molar excess over the normal pentane undergoing treatment therein, subjecting the normal pentane feed to contact with the catalyst in the presence of the added isobutane and a small amount of hydrogen halide during passage through the reaction zone for a period of about 1 to 15 minutes, maintaining within said reaction zone a reaction temperature ofv about to 200 F. such that there is substantial conversion of normal pentane to isopentane with substantial reduction `in cracking and catalyst deterioration, and removing from said zone a reacted hydrocarbon mixture containing' isopentane in substantial amount.

5. A process for the isomerization of a'hydrocarbon feed consisting essentially of normal peny tane which comprises continuously passing a stream of said feed through a reaction zone containing a metallic halide isomerization catalyst, continuously introducing to said zone isobutane in an amount suiiicient-l to maintain a substantial molar excess over the normal pentane undergoing treatment therein, subjecting the normal pentane feed to contact withV the catalyst in the presence of the added isobutane and a small amount of hydrogen halide during passage through the reaction' zone, maintaining isomerizing conditions Within said zone at a temperature not in excess of about 300 F. such that there is substantial conversion of normal pentane to isopentane with substantial reduction in cracking and catalyst deterioration, removing from the reaction zone a reacted hydrocarbon mixture containing isopentane and butanes, fractionatingsaid mixture to form a hydrocarbon fraction rich in butanes and recycling at least a portion of said butane fraction through the reaction zone.

6. In a process for isomerization of a hydrocarbon fraction comprising' essentially normal pentane by contact with an isomerization catalyst for normal parailin hydrocarbons maintained in a reaction zone under isomerizing conditions at a temperature not in excess of about 300 F. such that conversion of normal pentane to isopentane is normally accompanied by formation of substantial amounts of hydrocarbons of higher molecular weight than pentane, the step which comprises introducing isobutane to the reaction zone in an amount sufficient to maintain a substantial molar excess oi isobutaneover nor,-

ving substantial conversion mal pentane undergoing treatment therein such that the aforesaid formation of hydrocarbons of higher molecular weight than pentane is substantially inhibited.

7. In a process for isomerization of a hydrocarbon feed comprising essentially normal pentane by contact with an isomerization catalyst for normal paraiiin hydrocarbons maintained in a reaction zone` under isomerizing conditions ysuch that conversion of normal pentane to isopentane is normally accomi inied by formation ofA substantial amounts of hydrocarbons of higher molecular weight than pentane, the method which comprises passing a. stream of said normal pen- -tane feed to the reaction zone, introducing isobutane to thereaction zone in an amount suiiicient to maintain 'a substantial molar excess of isobutane overrthev normal pentane undergoing treatment therein and suiilcient to inhibit substantial formation of the aforesaid hydrocarbons of higher molecular weight than pentane, effectof normal pentane to isopentane during passage through the reaction zone, and removing from the reaction zone a hydrocarbon mixture containing isopentane in substantial amount.

8. In a process for the isomerization of a hydrocarbon feed comprising essentially normal pentane by contact with an isomerization catalyst for normal parafilns maintained in a reaction zone under isomerizing conditions such that conversion of normal pentane to-isopentane is normally accompanied by formation of substantial amounts of hydrocarbons of l weight than pentane. the method which comprises passing said feed to the reaction zone containing .a metallic halide isomerization catalyst, in-

` troducing isobutane to the reaction zone in an amount sufcient'to maintain a substantial molar excess of isobutane over the undergoing treatment therein, inhibit substantial formation of the aforesaid hydrocarbons -of higher molecular weight than pentane, subjecting the pentane feed to contact with the catalyst in the presence of the added isobutane and a small amount of hydrogen halide such that substantial conversion 'of normal pentane to isopentane is effected, and removing from the reaction zone a hydrocarbon mixture con-` taining isopentan'e in substantial amount.

9. The method tained in the reaction zone is about 2 to 4 parts of isobutane to. 1 part of pentane.'

10. The method according to the isomerization catalyst comprises aluminum halide.

higher molecular' normal pentane and sunicient to claim 8 in .which ing conditions at 11. The method according to claim 8 in which the isomerization reaction is effected at a temperature not in excess of about 300 F.

12. In aproc'ess vfor isomerization of a hydrocarbon feed comprising essentially normal pentane by contact with'an isomerization catalyst for normal'paramn is normally accompanied by formation of substantial amounts of hydrocarbons of higher molecular weight than pentane.- the method which comprises -passing a stream of said feed to the reaction 'zone containinga metallic halide isomerization catalyst maintained under isomeriza' temperature not in excess of about 300 F., introducing isobutane to the reaction zone in an amount sufficient to maintain a substantial molar excess of isobutane over the normal pentane undergoing treatment and' sufficient to inhibit substantial formation of the aforesaid hydrocarbons of higher molecular weight-than pentane, subjectixg the feed hydrocarbon to contact with the 'catalyst in the presence of the added isobutane and a small amount of hydrogen halide such that substantial conversion of normal pentane to isopentane is effected, removing from the reaction zone a mixture of hydrocarbons comprising C4 and Cs hydrocarbons including isopentane.. separating C4 hydrocarbons from said withdrawn mixture and returning the separated C4 hydrocarbons at least in part to the reaction zone. y

13.- A process for the isomerization of a hydrocarbon feed consisting essentially of lnormal pentane which comprises continuously passing a stream. of said feed througha reaction zone containing ametallic halide isomerization catalyst maintained under isomerizing conditions at a temperature not in excess of about 300 F., continuously introducing to, said zone C4 para-nin' hydrocarbon in an amount sufficient to maintain a vsubstantial molar excess of isobutane over the according to claim 8 inwhich l f the ratio'of isobutane to normal pentane maini with the catalyst in parafiln hydrocarbon tarioration,

normal `pentane undergoing treatment therein, subjecting the normal pentane feedto contact the presence of the added C4 and a small amount of hydrogen halide during passage through the reaction zone such that there is substantial conversion of normal pentane to isopentane -with sub stantial reduction in cracking' and catalyst deand removing from said` zone a re-- hydrocarbon mixture containing isopene tane in substantial amount. g

ARTHUR R. GOLDSBY." EUGENE E, SENSEL.

hydrocarbons maintained in a reaction zone under isomerizing conditions such thatconversion of normal pentane to isopentane

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