US2339849A - Treatment of paraffin hydrocarbons - Google Patents

Description

Jan 25, 1944,` A. R. GoLDsBY E-rAL 2,339,349

TREATMENT OF PARAFFIN HYDROGARBONS Filed June so, 1939 ARTHUR R.GoLnsaY EUGENE ESENssl.

INVENTORS s Y E N n A m E H T Patented Jan. 2 5, 1944 UNITED STATES PATENT 1f orifice .TREATMENT oF rm maooAaBoNs. I y

o! Delaware Application June so, 1939, sei-loi No. 282,114' .l ,f i.

1o claims (o1. '26osaam l 'Ihis invention relates to the treatment or reforming 4oi naphthas and has to do particularly with the isomerization of straight run or virgin naphthas to improve the antiknock value and volatility.

Straight run naphthas from parainic or mixed base crudes contain large amounts of parafn hydrocarbons which consist in substantial amount of straight chain hydrocarbons having a relatively low antiknock value. It is an object of the present invention to convert a substantial amount of such straight chain paraiin hydrocarbons into branch chain or isoparaflin hydrocarbons of high antiknock value.

It has been proposed heretofore to isomerize certain normally gaseous hydrocarbons and lower boiling normally liquid hydrocarbons, such as normal butane and normal pentane, to corresponding isoparamns b y contacting the normal parailns 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 hy#- drogen` chloride, as promoters. It has also been proposed to subject gasoline of boiling range of about 130 to 190 F. to isomerization 1n the presence of aluminum, chloride and hydrochloric" acid I and accompwying deterioration of the catalyst which ni'f-lnally occur with the higher boiling normal paraiins, may be substantially inhibited or by carrying out the isomerization operation'fin the presence of a large proportion of a low boiling isoparaiiln, such as isobutane and isopentane. Moreover, the formation of high boiling. material above the gasoline boiling range is avoided. .The reactions involved are not fully understood. It isthought that the isoparailin may inhibit the cracking and the resultant formation of unsaturated hydrocarbon fragments or A a continuous operation.

olens; or the isoparamn may react with the olens as formed to produce saturated alkylation products; lor a combination of the above two reactions may occur.

The catalysts which are useful includel any of v the active lsomerization catalysts, such as metallic halides, preferably used in the presence of small amountsof promoters, such as hydrogen halides. While any ofthe anhydrous metallic halides which will function as alkylationcatalysts are contemplated, for practical purposes aluminum halides, such as aluminum chloride, and alu, minum bromide are preferred. Likewise any of the hydrogen halide promoters, such as HC1. HBr, H1 and HF, may be used, but it is preferable to use hydrogen chloride. The metallic halide catalyst may be in solid, granular or lump form, or in the case of AlBrs attemperatures above 208 F. in liquid form, or supported on a solid absorbent such as synthetic and natural clays, pumice, brick, coke, activated alumina, and activated carbon. The hydrogen halide promoter may be added as such or may be generated in situ from the metallic halide by adding the rewhich reacts with the metallic halide.v

The process may be carried out in a batch or continuous type of operation, and preferably 'in The process is'preferably conducted as a cyclic operation in which the isoparatiinis recycled together with any Portion or all of the hydrogen halide promoter.

The amount of catalyst and promoter will vary. depending on the type of operation used. In a batch operation, it is contemplated that the catalyst may be about l to '40% or more by weight `based on the weight of tne hydrocarbon charge. The promoter may vary between about 0.1 and :1% or more, and preferably about 1%. In continuous operations, wherein the promoter is 'recycled, the range of the amounts of the catalyst and promoter will be much broader. For example,.tne amount of catalyst may range from 1 to 100% or more. while the promoter may vary 'from about 0.05 to 50% or more.

The invention is not restricted to any par-l ticular temperature and pressure. since the process may be operated successfully at temperatures` and pressures selected from quite wide ranges..

Thus, temperatures may range f'om about room temperature to about'300 F. The pressures may under atmospheric or subatmospheric pressures.

'I'he proportion of isoparaflin is influenced by the operating conditions and the nature of the charge. Larger amounts of isoparaiiin are advantageous when using higher temperatures and higher percentages of promoter and catalyst. Also when using the higher molecular weight chargestocks itis desirable to use higher ratios of isoparaln.

It is contemplated that the isoparaillns may vary from about 25% by volume of the hydrocarbon charge up to 1000% or more, and preferably a ratio of isobutane to hydrocarbon charge from about 1:1 to 5:1.

For purposes of illustration and without in any way limiting the invention, examples are given below of the treatment of straight run gasoline in the presence of aluminum chloride and hydrogen chloride, with and without the addition of isobutane. Example I is a batch operation, without the addition of isobutane. Example 1I is an operation similar to Example I except isobutane is added according to the invention. Example III is a continuous operation using added isobutane in accordance with the invention. In Examples II and III the gasoline was converted into a product of improved volatility and antiknock value with substantially no loss from catalyst deterioration, whereas in Example I the gasoline was impaired in volatility and there was a substantial loss in the form of a liquid complex of hydrocarbon and deteriorated catalyst.

Example I A straight run gasoline from Mid-Continent crude oil was mixed with 20% of granular aluminum chloride, and 2.5% of HCl by weight. The mixture was agitated for 3 hours at about 198 to 204 F.

The percentage of the gasoline charge recovered as gasoline and o-gas was 86.8%. The amount of hydrocarbons in the gasoline charge combined with the catalyst to form a dark reddish colored liquid-aluminum chloride-hydrocarbon complex containing all of tHe catalyst was 11.1%. The remaining products comprised HC1 and'gases lost during the reaction.

'Ihe tests on the original gasoline and gasoline product after stabilization, are as follows:

Before i Alter treatment 10% A' sl" mu treatment with ich with Alon 13o I. B. P 2i ies 67. 120 iso 10a ist 19s 20 i60 211 30 184 222 40 204 232 50 225 240 60 241 250 70. 25o 200 sofr 280 274 r m 99. 0 Percent rec 96. 0

1 o Percent res 0. 9

Percent loSS 3. 1

C. F. R. M. knock rating 53.9 No. tetraethyl lenti... 67.5

65.0 1 0c. tetraethyl lead..-- 79.4

73.0 2 cc. tetraethyl lead 83.5

Example II Another sample of the same gasoline as used in Example I was agitated with 20% by weight of granular aluminum chloride, 5.1% by weight of HCl and about 386% by weight of isobutane based on the gasoline charged, in a pressure autoclave for three hours at about 190 to 200 F.

The products consisted of a gasoline and isobutane layer and a catalyst layer which differed from Example I in that the catalyst layer was not a liquid but a granular solid much the same as the original aluminum chloride'.

The untreated and stabilized treated gasolines tested as follows:

untreated 10% A. s. r. M. distillation i Treated 5 0 9 36 C. F. R. M. octane number. 63 3 The volatility of the upper portion of the dis-v tillation range is improved, over Example I above, and the end point is within the gasoline range.

Example' 1H A straight run Mid-Continent naphtha, similar to that in the preceding examples, and isobutane in the ratio of about four parts isobutane by volume to one of naphtha, and about 0.5% byweight 'of HC1 based onthe mixture, is continuously fed to a tower containing aluminum chloride wherein the mixture is contacted with the catalyst at about to 210"v F.` After separating any complex and catalyst, the reaction products are subjected to debutanization to separate the gases, containing isobutane and HC1, which are recycled. About 95% to 99% of the naphtha with an octane increase of about 10 points is recovered.

The invention is applicable to the treatment of various fractions of normally liquid paraiiln hydrocarbons, such as pentane, hexane, heptane or octane, or mixtures of two or more thereof as well as virgin naphthas of various boiling ranges.

The invention will be further. understood from the accompanying drawing which shows a diagrammatic sketch of one form of apparatus for carrying out continuously the process of the invention.

Referring to the drawing, the charge stock is introduced through the line I by the pump 2 into catalyst chamber or tower 4 containing the catalyst 5. Any liquid complex or partially spent catalyst in reactor 5 may be withdrawn from this reactor through line E. The aluminum chloride contained in the complex may be recovered by destructive distillation of the complex. The reaction products are transferred from the upper portion of the catalyst chamber through the line l 2,389,849 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 through the line II ,tol a debutanizer or fractionator I2 wherein the hydrogen chloride and normally gaseous hydrocarbons, comprising chiefly isobutane, are separate'd and removed overhead through thel vapor line I5 and condenser I6. If isopentane is used 1 instead of or with the isobutane, it may also be removed all or in part with the overhead from the fractionator I2. `The overhead products may berecycled all or in part through the line I8, pump I9 and line 20 to the catalyst chamber. In case the products removed overhead from the debutanizer I2 contain constituents which are undesirable for recycling, such as propane, it may be desirable to remove such materials or to discard a fraction in order to prevent them from building up in the system. For this purpose, any portion of the products may be passed through the line 2| by the pump 22 to a fractionator 24.

In the fractionator a separation is made between` isobutane and/or isopentane and lighter gases which are released from the upper portion of the fractionator through the line 25. The isobutane fractionv is withdrawn from the lower portion of the fractionator through the line 26 and may be passed all or in part through the line 38 by the pump 31 for recycling. If desired, hydrogen chloride may be recovered from the light gases withdrawn from fractionator 24 through line 25, and recycled to reactor 5.

The debutanized hydrocarbons are withdrawn from the bottom of the'debutanizer through the.

line 28, pump 29 and line 30 to a fractionator 3|. In the fractionator 3| the products are fractionally distilled to separate the gasoline fraction from bottoms which are withdrawn from the lower portion of the fractionator through the line 32. The gasoline vapors are removed overhead from the fractionator through the line 33 and condenser 34 to an accumulator 35.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing fromthe 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 improving the antiknock value of naphtha rich in normal parailins which comprises subjecting the naphtha to contact with a.`

metallic halide isomerization catalyst -normally .tending to deteriorate, and form hydrocarbon complex, and eecting the contact treatment at an isomerizing temperature not in excess of about 300 F. and in the presence of an added isoparaffin ofthe class of isobutane andisopentane in amount by weight substantially in excess of the weight of the naphtha feed and such that naphtha feed hydrocarbons are isomerized to products the reaction in the proportion of from about fourA to ten volumes lof isoparaiiins to one volume of naphtha.

5. A process for the isomerizatlon of naphtha hydrocarbons whichcomprises continuously passing a stream of naphtha feed hydrocarbon through a reaction zone containing an isomerizatlon catalyst maintained under conditions such that isomerizationconstitutes the principal reaction and such that the reaction is normally ac` companied by formation of a small amount of material boiling above the gasoline boiling range, continuously introducing to said zone a stream of low boiling isoparafn hydrocarbon in an amount suiiicient to maintain therein low boiling isoparaiiin in an amount-substantially greater by boilingisoparaflln at a temperature not in excess of about 300 F. with substantial reduction in cracking and catalyst deterioration over that obtaining when the reaction'is eected in the absence o'f added low boiling isoparaflin, and continuously removing from the reaction zone a reacted hydrocarbon mixture containing isomerized naphtha hydrocarbons.

6.- The process according to claim 5 in which the catalyst comprisesmetallic halide activated with hydrogen halide.

7. The process according to claim 5 in which the low boiling isoparaiiin hydrocarbon maintained in the reaction zone consists essentially of isobutane.

8. The process according to claim 5 in which the low boiling isopa-ain maintained in the reaction zone amounts to at least about 400% by volume of the naphtha feed hydrocarbon undergoing treatment.

9. A process for the isomerization'of naphtha hydrocarbons which comprises continuously passing a stream of naphtha. feed hydrocarbon through a reaction zone containing an isomerization catalyst maintained under conditions such that isomerization constitutes the principal reaction and such that the" reaction is normally accompanied by formation of a small amount of material boiling above the gasoline boiling range. continuously introducing to said zone a stream of low boiling isoparaiiin hydrocarbon in an amount suflicient to maintain therein low boiling isoparail'in in an amount substantially greater by volume than the naphtha feed undergoing treatment therein and suicient at least to substantially reduce the formation of said high boiling material, effecting substantial isomerization` of naphtha feed in the presence of the added low boiling isoparain with substantial reduction in cracking and catalyst deterioration over that obtaining when the reaction is eiected in the ab of improved antiknock value without substantial catalyst deterioration and with relatively little conversion to hydrocarbons boiling below and above the boiling range of the naphtha feed.

2. The method according to claim 1 in which the catalyst comprises aluminum chloride and hydrogen chloride.

3. The method according to claim 1 in which the catalyst comprises aluminum chloride and hydrogen chloride and the contact treatment is effected at a temperature of about 190 to 210 F.

4. The method according to claim `1 in which the isopar'aiiln and the naphtha are charged to sence of added low boiling isoparain. and con` said reaction zone. subjecting it therein to contact with the catalyst in the presence o! a low boiling isoparamn. added to the reaction, effecting substantial lsomerization of naphtha feed hydrocar-bons with substantial reduction in cracking and catalyst deterioration over that obtained when the reaction is effected inthe absence of added low boiling isoparaln, continuously discharging from the reaction zone 'a stream of isomer-ization naphtha hydrocarbons and added low boiling isoparamn, separating from the discharged stream an isoparamn fraction lower boil- .ing than. said lsomerized naphtha' hydrocarbons and recycling said separated lsoparamn fraction to the reaction zone in an amount'sumcient to provide therein low boiling isoparamn in an amount substantially greater by volume than the naphtha feed undergoing ltreatment therein and ysulllcient at least to substantially reduce thefor-

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