US2411054A - Catalytic conversion of hydrocarbons - Google Patents

Description

Nov. 12, 1946. E. PEVERE CATALYTIC CONVERSION OF HYDROCARBONS Filed April 15. 1942 ERNEST E PEyERE IN VEN TOR Patented Nov. 12, y1946 UNI-TED STA-ras PATENT OFFICE CATALYTIC CONVERSION F HYDROCARBONS Ernest F. Pevere, Beacon,

Texas Company, tion of Delaware N. Y., assigner to The New York, N. Y., a corpora- Application April 15, 1942, Serial No. 439,048

2 Claims. (Cl. 26o-683.5)

eiTecting the reaction in the presence of a small amount of olefinic hydrocarbon in such a way as to substantially promote the lsomerization reaction.

More specifically the invention contemplates eiecting the reaction so that a relatively small amount of low boiling olen, inthe presence of isoparafiin hydrocarbon,` is maintained in the isomerization reaction, the isoparain advantageously being present in substantial amount relative to the olefin at and subsequent to the initial contact between the feed hydrocarbon and the conversion catalyst. Advantageously' both isoparain and oleiin are maintained present throughout the entire reaction.

It has been found that by carrying out the conversion in the foregoing manner and particularly at temperatures lower than normally used in isomerization, the hydrocarbon reaction product obtained contains a materially greater proportion of isomerized` feed hydrocarbons than when the reaction is carried out in the substantial absence of olefin hydrocarbon. The reason for this is not clearly understood, but nevertheless the existence of a substantial promoting effect through having both olen and isoparamn present at least during the initial contact between iced hydrocarbon and catalyst appears to be substantiated by examples which will be describedA hereinafter.

In the isomerization of normal paraffin hydrocarbons with a, metallic halide catalyst it has been found desirable heretofore to remove olens from the feed to the reaction zone since under ordinary conditions oleiins, if present, appear to cause catalyst deterioration and result in a substantial decrease in the yield of isomerized hydrocarbons per unit of catalyst employed.

The present invention, however, involves having a substantial amount of isoparain present with the olen during the initial contact between the feed hydrocarbon and the catalyst anf throughout substantially the entire reaction. Advantageously the isopara'in is present in substantial molar excess over the olefin. It appears that .under these conditions the olefin is utilized in alkylatlng isoparamns present in the reaction zone and is thereby consumed in the production of valuable hydrocarbon products rather than entering into reaction with the catalyst to form complex. At any rate under such conditions a definite promoting effect is realized.

Moreover, the conversion reaction can be carried out at lower temperatures than prevail in the ordinary isomerization reaction. In addition the character of the product is diierent. For example, when isomerizing normal butanle by the action of aluminum chloride and hydrogen chloride at a temperature of about 120 F. in the presence of a small amount of ethylene and in accordance with the method of this invention, the product contains very lsubstantial amounts 0f neohexane and methylpentanes.

The following experiments comprise batch liquid phase experiments in which normal butane was converted by the action of aluminum chloride and hydrogen halide at a temperature of about 150 F. In each experiment anhydrous aluminum chloride, hydrogen chloride and some hydrocarbon were charged to a reaction .vessel provided with a stirrer and means for heating the vessel. The stirrer was then started and the temperature adjusted to the desired point, lfollowing l which hydrocarbon feed was added slowly over a period of 1 hour, the mixture being stirred for 30 minutes afuter completion of the addition of the hydrocarbon. Thereafter, the reaction mixture was drawn off and the hydrocarbon product separated into gaseous and liquid fractions, respectively. The gaseous fraction comprised essentially isobutane, normal butane and lighter hydrocarbons, while the liquid fraction comprised normally liquid hydrocarbons free from butanes.

The following tabulation compares the amount of catalyst, hydrocarbon charge, and hydrocarbon product in parts by weight. 'I'he composition of the gas and liquid fractions of the product is shown in per cent by weight.

A B C Catalyst:

Aluminum chloride 1li) 110 Hydrogen chloride 10l lll l0 Reaction temperature, F 15o 15o 150 Hydrocarbon charge:

Normal butano 540 53D 392 Isobutanc i 0 0 4l Ethylene 0 26 25 Mols of butano per mol oi ethylene. 0 10, 0 V8, 3 Mols ol isobutane per mol of lethylene 0 0 0 8 Hydrocarbon product: (las fraction 530 50o 404 Composition oi gas fraction:

Percent lighter than isobutane.. 0. l 0. 5 l. 8 Percent isobutane 11.0 19. 4 42. 1 Percent normal butanc 87. 5 76. 0 5l. 9 Percent isopentane and heavier 1. 4 4. 1 4, 2 Yield ol isobutane, basis normal butane charged 10. 2 18. (l 32. 9 Liquid fraction None 40| 5S Percent yield of liquid fraction basis ethylene- 154A 252 In experiment A the hydrocarbon charge. conslsted lsolely of normal butane. In experiment B ethylene and normal butane was introduced continuously throughout the ,entire run. In experiment C isobutane was present initially in the reactor and ethylene and normal butane were introduced continuously throughout the entire run.

In experiment A it will be observed that under the conditions employed, the yield of isobutane amounted to 10.2% by weight of the normal butane charged. However, in experiment B with a small amount of ethylene present the yield of isobutane obtained amounted to 18.0% by weight of the normal butane charged. On the other hand, in experiment C where a small amount of lsobutane was initially present along with the ethylene theconversion of normal butane to isobutane was nearly doubled. l The results in experiments Band C calculated on the basis of 100 pounds of normal butane charged may be tabulated as follows:

hai-ge:

Normal butane. Ethylene Isobutane Products:

v Normal butane Isobutane Normally liquid fraction l* aus: om

Catalyst:

Aluminum chloride 110 110 Hydrogen chloride 30 15 Reaction temperature. F 150 120 Hydrocarbon charge: Normal butane 331 '257 Isobutane 85 80 Ethylene 32 25 Mols oi butane per mol oi ethylene. 6. 3 6. 2 Mols of isobutane per mol of ethylene l. 1 1.1 Hydrocarbon product: Gas fraction 310 250 Composition of gas fraction:

Percent lighter than isobutane 1.7 5. 7 Percentl isobutane 43. 36. 7 Percent normal butane 53.1 55. 4 Percent isopentene and heavier 1.7 2. 2 Yield ol isobutane, basis normal butane charg d 3i l 23. 3 Liquid fraction 67 40 Percent yield oi liquid fraction basis ethylene... 210 160 The liquid `fraction from experiment D was analyzed and found lto comprise hydrocarbons boiling over the range about 86 to 145 F. and

-about 60% of this fraction comprised isopentane,

carbon'atoms as well as light naphtha fractions I boiling in the range up to about 150 to 170 F.,

for the purpose of converting normal and The isoparaiiin introduced to the reaction ad- I vantageously comprises a relatively low boiling isoparaiiin such as isobutane or isopentane. It may be obtained from an extraneous source or may be separated from the reaction product and recycled to the reaction zone. The isoparafiin is maintained in the reaction in the ratio of from about 1 to 10 mols of isoparamn per mol of olen. As indicated in experiment'C good results In no case, however, should the isoparaflin exceed about 50% by volume of the normal paraffin undergoing conversion in the reaction zone.

Reference may be had to the accompanying drawing comprising a. flow diagram illustrating one mode of practicing the invention in a continuous flow operation.

A hydrocarbon such as a normal paraffin hydrocarbon or mixture consisting. essentially or normal paraffin hydrocarbons is drawn from a source not shown through a pipe I and conducted'` to a heater 2 wherein it is heated to the reaction temperature. Olen may lloe present in the feed in the requisite amount or may be'added separately as mentioned later. The heated feed hydrocarbon or hydrocarbon mixture is conducted from the heater through a pipe 3 -to a conversion unit 4 wherein it is subjected to the action of the conversion catalyst. For example, a suitable conversion catalyst comprises aluminum chloride activated with hydrogen halide.

' The reacted, together with unreacted, hydrocarbons are drawn'off from the conversion unit through a pipe 5 and advantageously introduced to a fractionator 6. The hydrocarbons' are advantageously scrubbed upon removal from the conversion unit to remove entrained catalyst and promoter.

The fractionator 6 may Ibe operated so as to y separate the hydrocarbon mixture into any desired number of fractions or may be operated so as to remove only gaseous constituents, the degasiiled hydrocarbons passing to a separate fractionator fol` further treatment. However, as indicated in the drawing the fractionator 6 may be operated so as to remove overhead a gas fraction through a pipe l and branch pipe 6.

Since this gaseous fraction removed through the pipe 'l may comprise substantial amounts of vhydrogen chloride or other gaseous agents used in the reaction it is usually desirable to recycle the gaseous material to the conversion reaction.

. In such case the recycled mat/arial is returned through a, pipe 0.

A side stream comprising isomerized hydrocarbons may be drawn off through a pipe I0 and cooler Ii while a heavier fraction may be drawn off in liquid form from the bottom of the frac-a tionator through a pipe I2.

If desired the liquid fraction drawn olf through the pipe I2 may be passed through a branch pipe I3 for introduction to another fractionator I 4 wherein the hydrocarbons are subjected to further fractionation. In this instance an overhead fraction may be removed through a, pipe I5 and a cooler. I6 while a liquid fraction may be drawn off from the bottom of the fractionator through a pipe Il.

Any portion, of either or both of the fractions removed through the coolers lI and I8, may be recycled to the conversion unit.

For example, when charging a feed Ahydrocarbon consisting of normal butane the product fraction removed from the cooler II may consist essentially of isobutane, while the product fraction removed from the cooler I6 may comprise essentially unreacted normalbutane. The unreacted normal butane is advantageously recycled all or in part to the conversion unit together with a small amount of isobutane which may be obtained from the stream drawn off from the cooler Il. However, it is contemplated that the fractionation operations may be conducted so that the normal butane stream drawn oi from the cooler I6 contains a small but sufficient amount of isoparaflin to supply the isoparain required in the conversion unit.

The recycled hydrocarbons may be returned through a pipe communicating with the pipe 3 previously mentioned, or communicating by means of a branch pipe 2I with the pipe I previously mentioned.

Oleiln hydrocarbon obtained from an extraneous source is `conducted through a pipe 22 and advantageously commingled with the recycled' hydrocarbons. On the other hand, it may be injected directly with the feed hydrocarbon o r may be injecteddlrectly to the conversion unit whichever is desired. It may be injected in a, stream whlchis rich in isoparain, or in a stream which is rich in normal parafllnl Isoparafiln from an extraneous source and which may be necessary in the early stages of the operation may be introduced through a pipe 23.

Makeup catalyst and promoter may be passed to the conversion unit from a source not shown through a pipe 24. f

The conversion unit may be of any conventional type depending upon the type of conversion operation employed. Thus, the catalyst may be employed in either solid or liquid form although the liquid form is usually preferred. In such case the catalyst may comprise a solid catalyst dissolved or suspended in a liquid carrier such as hydrocarbon or metallic halide-hydrocarbon complex. For example, an eiective catalyst comprises solid aluminum halide dissolved or suspended in aluminum halide-hydrocarbon corn-` plex.

The conversion unit may comprise a vessel containing a substantially stationary body of fluid catalyst through which the hydrocarbons undergoing treatment rise merely by difference in density. On the other hand, the reaction vessel may be of the agitated type, such agitation being imparted either by mechanical stirring means or by rapid circulation of hydrocarbon or catalyst mixture through the reaction zone.

with the agitated type of apparatus it is usual; 1y desirable to provide adequate settling space or auxiliary settling chambers wherein separation ployed such as aluminum chloride, aluminum bromide, zirconium chloride, beryllium chloride, titanium tetrachloride, stannic tetrachloride, antimony chloride, or mixtures of halides such as AlC13SbCl3, AlCla-NaCl, etc.

Suitable promoters other than hydrogen chlo-r y ride may be hydrogen bromide, hydrogen iodide, carbon tetrachloride, alkyl, aryl or acyl halides or any substance which is capable of liberating halogen halide `after coming into contact with the metallic halide catalyst. Chlorine, bromine and iodine may be injected for purposes of promoting the reaction. Alkyl halide formed by chlorination of a portion of the feed hydrocarbon to the reaction may be utilized as the promoter.

Other catalysts or promoters besides those speclcally mentioned above may be employed since it is contemplated that the process of this invention is applicable to the conversion of hydrocarbons by the action of any suitable catalyst wherein isomerization constitutes the principal reaction.

With an aluminum halide-hydrogen halide catalyst, such as aluminum chloride activated with hydrogen chloride, the temperature maintained in the reaction zone is preferably somewhat lower than that employed when eiecting isomerizatlon in the usual manner and in the absence of olefin. On the other hand, the temperature is somewhat above the range employed in the conventional alkylation reaction with this type of catalyst. For example, `:'Jhen isomerizing normal butane in the presence of ethylene in accordance with this invention the reaction temperature may range from about to 175 F. When isomerizing normal pentane the temperatures may range from about 75 `to 125 F.

The use of high promoter concentration facilitates Yemploying low temperatures suchthat the reaction may be carried out at even lower temperatures, as for example 0 F,

The feed hydrocarbon may be treated to remove objectionable compounds such as sulfur compounds and aromatic constituents, the presence of which is undesired when employing a catalyst such as aluminum halide.

The process of promoting the isomerization of a normal paran hydrocarbon, such as normal butane, to the corresponding isoparaiiin in the presence of an aluminum halide catalyst `and a hydrogen halide promoter at temperatures within the range of about 75 to 250 F., by adding to the normal parain charge a small proportion of an olen and also a small proportion of an isoparafhn, the'olen amounting to from a fraction or 1% to about 5% by volume of the total hydrocarbon feed, and the isoparain amounting to at least the molar equivalent of the olein but not exceeding about 10% by volume of the normal paraflin undergoing conversion in the reaction zone, is disclosed and claimed in the copending co-owned application of Eugene E. Sensei, Serial No. 606,446, :tiled July 21, 1945, as a continuationpresent in about 'an amount which conversion in the reaction zoner passing feed mixture to said reaction zone v sametherein in liquid phasein-'part of the copending application, Serial No. 439,031, iiled April 15e 1942.

Obviously many modifications of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope ythereof and, therefore, only such iimitations should be imposed as are pended claims. I claim:

1. The method for catalytically converting normal butane to more valuable saturated hydrocarbons, which comprises forming a hydrocarbon feed mixture consisting mainly of normal butane and containing minor` proportions of isobutane and a normally gaseous olefin, the olefin being 0.5 to not in excess of volume per cent of the total hydrocarbon feed mixture, and the isobutane being present in' from 1 to 10 mois per mol of olefin but not exceeding provides about 50% by volume butane undergoing thesaid on `the basiisl of the normal hydrocarbon and contacting the with an aluminum halide catalyst and a hydrogen halide promoter under conditions including a temperature within the range of about 100 to 175 F., whereby isomerization of normal butane indicated in the lapto isobutane constitutes normally liquid branchedand variations f the principal reaction and the production of chain paraffin hydrocarbons higher boiling than n-butane constitutes a substantial but minor reaction, removing hydrocarbon reaction products from said reaction zone, from said removed products as a principal final product oi' the process, separating a normally liquid fraction consisting essentially of said higher boiling branched-chain paraffin hydrocarbons as a substantial but minor final'product,l

also separating from said products an intermediate fraction consisting essentially of unconverted normal butane with a minor proportion about 10 of isobutane, and recycling' said intermediate i fraction to the reaction zone, the amount of normal butane thereby converted into isobutane and recovered as such in the final product being substantially greater than when the conversion is effected underthe same conditions with a feed.

consisting of normal butane and free from said isobutane and' olen.

,2. The method according to claim 1, wherein the normally gaseous olefin is ethylene, and the normally liquid product; contains substantial amounts of neohexane and methylpentanes.

separating isobutane

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